Technical Field

[1] The present invention relates to UTP cable, more specifically UTP cable which has a structure that prevents the cross talk among the twisted pairs for the improvement of the transmission capacity. Background Art

[2] Recently, unshielded twisted pair (UTP) cable has become more important as the communication technologies like Ethernet have developed radically.

[3] Generally, the UTP cable is fabricated in the following steps: electric wires consisting of conducting wires made of a conductor such as copper, or etc., and coated with insulation material are twisted to form twisted pairs. Four twisted pairs, in a typical but limiting scenario, are separated from the others by a separator are collected and then all of these are coated by insulation coating. In some cases only two or less pairs are separated from each other and coated with an insulation jacket.

[4] It has become desired to increase the information transmitting capacity of UTP cable as the information technology develops, and thus, UTP cable has been developed to provide a means to increase the information transmitting capacity.

[5] In the meanwhile, the UTP cables are classified by the identification characters such as category (or Cat.) and number in accordance with its signal transmitting capacity under international agreement, wherein the bigger number means the higher transmitting capacity.

[6] For example, UTP cable of Category 3 (Cat 3) can transmit signals to at least

16MHz, Category 5 and 5e to at least 100 MHz, Cat 6 to at least 250MHz, and now Category 6a can transmit to at least 500 MHz, wherein the higher modulation frequency is used, the more information can be transmitted.

[7] However, as the higher modulation frequency is used the noise caused by the cross talk among the conductors, and/or cables in a bundle, and the change of the impedance in the conducting wires is increased, results in a problem where the assortment of the signals gets more difficult to decipher in the signal receiver. For this reason, the limit of the UTP s cable transmitting capacity has been limited to lGbps in Category 5e and Category 6 cabling, until recently with the development of 10 gigabit Category 6a UTP cable.

[8] As the technology of information transmitting equipment develops the signal degradation due to cross talk in the cable compensated by way of compensation methods using digital signal processing (DSP) equipment and etc. so it is possible to transmit lOOOMbps (lGbps) using Cat 5e and Cat 6, and the standard committee of IEEE (Institute of Electrical and Electronics Engineers) officially decided 1000 Base-T as the standard Ethernet in the year of 1999.

[9] Meanwhile, in view of the developing trend of the related technology such as movie transmission technology and etc, the cable can transmit information in a higher level will be needed in the near future, so that major cable manufacturers and related system manufacturers are competitively investing for satisfying this need, and also in the IEEE a specialized committee is organized for standardization on high speed information transmission cable.

[10] For improvement of the transmission capacity, usually higher frequency is used, and that results in problems of proportional increase of insertion loss, impedance mismatching between the cable conducting wires and the equipment, and cross talk among the electric wires.

[11] Representative cross talks are RL (return loss), NEXT (near end cross talk), FEXT

(far end cross talk) and etc. and various methods are attempted to reduce them.

[12] Such a method to compensate in the transmission system itself or a method to modify the pitch of the twisted electric wires, or the diameters of the conductors, or insulated outer diameters, or the shape of the separator is attempted.

[13] As for the related patents for the increase of the transmission capacity of the UTP cable, in the early stage of development the cross talk among the inner electric wires was believed to be primary factor resulting in the worsening of the transmission quality and thus much effort was made to solve this problem.

[14] Primary related patents are US5,132,488, US5,969,295, US5,519,173, US5,952,615 and etc, wherein metal thin film is disposed in the sheath for the increase of the transmission capacity by decreasing the cross talk or an inner filler is inserted for the constraint of the cross talk.

[15] Moreover, in the recent time, the utilization of high frequency wave band is consistently attempted wherein the transmission is possible whose theoretical transmission capacity, that is Shannon capacity, is 20 Gbps or higher, and practical transmission capacity is lOGbps by broadening the utilizing frequency to the frequency band of 400MHz or higher, more specifically to the range of 500~650MHz.

[16] With regard to this utilization of the high frequency band, one of the important issues is to minimize the noise in the cable by matching the impedance of the single electric wire in the cable to around the international standard, or lOOohm, and thus by having the impedance between the cable and the equipment being matched with.

[17] Further, the UTP cable has a problem that the electromagnetic field induced in the respective twisted pair induces an alien cross talk which affects other twisted pair.

[18] Regarding this alien cross talk, the controlled range and specific control value is provided in Sectional specification article 3.3.10 of Multicore and symmetrical pair/ quad cables for digital communications- Part 5: Symmetrical pair/quad cables with transmission characteristic up to 600MHz- Horizontal floor wiring, IEC61156-5.

[19] Recently, various researches are proceeding for reducing this alien cross talk, especially much effort is being made for the computation of the condition on the pitch of the respective twisted pair and the collective pitch. Disclosure of Invention Technical Problem

[20] The purpose of the present invention for solving the above-described problems is to provide UTP cable which satisfies the condition of the pitch of the twisted pairs and the collective pitch for reducing the alien cross talk.

[21] Another purpose of the present invention is to provide UTP cable having a structure which prevents the cross talk between the adjacent twisted pairs. Technical Solution

[22] The purposes can be accomplished by the UTP cable according to the present invention comprising the first, the second, the third and the fourth twisted pairs which are successively provided in clockwise or counterclockwise direction and each of which is formed by two electric wires twisted with each other helically to define the pitches; a separator which separates the first, the second, the third and the fourth twisted pairs from one another; collective pairs which includes the first, the second, the third and the fourth twisted pairs and the separator and are twisted helically to have a collective pitch; and a sheath which wraps the collective cable, wherein

[23] the collective pitch is 40 to 200 millimeter,

[24] the pitch of the first twisted pair is 11.7(± 0.3) millimeter,

[25] the pitch of the second twisted pair is 10.3(± 0.3) millimeter

[26] the pitch of the third twisted pair is 8.6(± 0.3) millimeter and

[27] the pitch of the fourth twisted pair is 9.4(± 0.3) millimeter.

[28] In this regard, rip-cord can be comprised in the inner part of the sheath for the easy strip of the outer cover of the sheath.

[29] Still further, the purposes can be accomplished by the UTP cable according to the present invention comprising the first, the second, the third and the fourth twisted pairs which are successively provided in clockwise or counterclockwise direction and each of which is formed by two electric wires twisted with each other helically to define the pitches; a separator which separates the first, the second, the third and the fourth twisted pairs from one another; collective pairs which includes the first, the second, the third and the fourth twisted pairs and the separator and are twisted helically to have a collective pitch; and a sheath which wraps the collective cable, wherein [30] the collective pitch is 40 to 200 millimeters,

[31] the pitch of the first twisted pair is 11.7(± 0.3) millimeter,

[32] the pitch of the second twisted pair is 8.6(± 0.3) millimeter

[33] the pitch of the third twisted pair is 10.3(± 0.3) millimeter and

[34] the pitch of the fourth twisted pair is 9.4(± 0.3) millimeter.

[35] In this regard, rip-cord can be comprised in the inner part of the sheath for the easy strip of the outer cover of the sheath.

[36] Still further, the purposes can be accomplished by the UTP cable comprising the first, the second, the third and the fourth twisted pairs which are successively provided in clockwise or counterclockwise direction and each of which is formed by two electric wires twisted with each other helically to define the pitches; a separator which separates the first, the second, the third and the fourth twisted pairs from one another; collective pairs which includes the first, the second, the third and the fourth twisted pairs and the separator and are twisted helically to have a collective pitch; and a sheath which wraps the collective cable, wherein

[37] the collective pitch is 40 to 200 millimeters,

[38] the pitch of the first twisted pair is 12.0(± 0.3) millimeter,

[39] the pitch of the second twisted pair is 10.3(± 0.3) millimeter

[40] the pitch of the third twisted pair is 8.6(± 0.3) millimeter and

[41] the pitch of the fourth twisted pair is 9.4(± 0.3) millimeter.

[42] In this regard, rip-cord can be comprised in the inner part of the sheath for the easy strip of the outer cover of the sheath.

[43] Still further, the purposes can be accomplished by the UTP cable comprising the first, the second, the third and the fourth twisted pairs which are successively provided in clockwise or counterclockwise direction and each of which is formed by two electric wires twisted with each other helically to define the pitches; a separator which separates the first, the second, the third and the fourth twisted pairs from one another; collective pairs which includes the first, the second, the third and the fourth twisted pairs and the separator and are twisted helically to have a collective pitch; and a sheath which wraps the collective cable, wherein

[44] the collective pitch is 40 to 200 millimeters,

[45] the pitch of the first twisted pair is 12.0(± 0.3) millimeter,

[46] the pitch of the second twisted pair is 8.6(± 0.3) millimeter

[47] the pitch of the third twisted pair is 10.3(± 0.3) millimeter and

[48] the pitch of the fourth twisted pair is 9.4(± 0.3) millimeter.

[49] In this regard, rip-cord can be comprised in the inner part of the sheath for the easy strip of the outer cover of the sheath. Advantageous Effects

[50] According to the present invention, it is possible to provide UTP cable with its conditions on the pitch and the collective pitch optimized so that electromagnetic interaction between the twisted pairs can be minimized.

[51] Further, it is possible to provide UTP cable having a structure which prevents the cross talk between the adjacent twisted pairs from taking place.

[52] Particularly, the present invention described in the above can be effectively utilized in a transmission network of 10 gigabyte level as a signal transmission system of the UTP cable made of copper wherein alien cross talks must be suppressed. Brief Description of Drawings

[53] The drawings attached to the present invention illustrate the preferable embodiment of the present invention, only helps further understanding of the idea of the present invention along with the detailed description of the present invention described in the below, and thus the present invention is not limitedly interpreted to the matters shown in the drawings.

[54] Fig. 1 is a perspective view of the UTP cable according to the present invention,

[55] Fig. 2 is a cross-sectional view of the UTP cable according to the present invention,

[56] Fig. 3 is a general view illustrating the pitch p of the twisted pair according to the present invention,

[57] Fig. 4 is a graph by the measurement of the cross talk of the UTP cable having different pitch values from the optimized pitches according to the present invention, and

[58] Fig. 5 is a graph by the measurement of the cross talk of the UTP cable having the optimized pitches according to the present invention.

[59]

[60] *Reference numerals of primary elements in the drawings*

[61] 100: conduction wire 110: electric wire

[62] 120: twisted pair 121,122,123,124: the first, the second, the third and the fourth twisted pair

[63] 125: collective twisted pair 130: separator

[64] 140: sheath

Mode for the Invention

[65] Hereinafter, the present invention is described in detail with reference to the attached drawings.

[66] Before the detailed description, it should be noted that the terms used in the present specification and the claims are not to be limited to their lexical meanings, but are to be interpreted to conform with the technical idea of the present invention under the principle that the inventor can properly define the terms for the best description of the invention made by the inventor.

[67] Therefore, the embodiments and the constitution illustrated in the attached drawings are merely preferable embodiments according to the present invention, and thus they do not express all of the technical idea of the present invention, so that it should be understood that various equivalents and modifications can exist which can replace the embodiments described in the time of the application.

[68] Fig. 1 show a perspective view of the UTP cable according to the present invention, fig. 2 shows a cross-sectional view of the UTP cable according to the present invention and fig. 3 show the pitch p of the twisted pair according to the present invention.

[69] Referring to Fig. 1 to 3, the UTP cable according to the present invention comprises the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 which are successively provided in clockwise or counterclockwise direction and each of which is formed by two electric wires twisted with each other helically to define the pitch p; a separator 130 which separates the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 from one another; collective pairs 125 which includes the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 and the separator 130 and are twisted helically to have a collective pitch P; and a sheath 140 which wraps the collective cable, wherein the collective pitch is 40 to 200 millimeters, the pitch p of the first twisted pair 121 is 11.7(± 0.3) millimeter, the pitch p of the second twisted pair 122 is 10.3(± 0.3) millimeter, the pitch p of the third twisted pair 123 is 8.6(± 0.3) millimeter and the pitch p of the fourth twisted pair 124 is 9.4(+ 0.3) millimeter.

[70] Herein, the condition having the above numerical values is defined as <optimal pitch p condition 1>.

[71] The UTP cable has a structure wherein a plurality of the twisted pairs, which is formed by two insulation-coated wires 110 twisted with each other, are collected and exemplary four twisted pairs 120 are collected in the sheath 140, and the collective twisted pairs are referred to as the collective pairs 125.

[72] Further, the separator 130 is inserted in the UTP cable including the plurality of the twisted pairs 120 which separates the twisted pairs 120 from one another so that the alien cross talk(hereinafter, referred to as cross talk) among the twisted pairs 120 can be prevented.

[73] The separator 130 desirably has a structure that it includes four separation walls which intersect one another such that the walls separate each of the twisted pair 120 from other twisted pairs, and desirably has a thickness of 0.2 ~ 1.0mm.

[74] The separator 130 makes the distance among the twisted pairs 120 bigger so that the cross talk among the adjacent twisted pairs 120 is decreased. [75] Further, the separator 130 desirably is made of dielectric substance such as polyethylene (PE) or polypropylene (PP).

[76] With regard to the shape, the separator 130 is illustrated as being cross-shaped in fig.

2, however, the shape of the separator 130 is not limited to the illustrated shape, but can have other shapes.

[77] Further, the sheath 140 is coated on the collective pairs 125 to wrap it, and is made of high molecular resin and conducting substance.

[78] In the meanwhile, the pitch p, indicates the length of the twisted pair 120 when the two electric wires 110 form a pair and unit pitch is applied to the pair (which means that the pair is twisted by one rotation), whilst the collective pitch P indicates the length of the collective pairs 125 when unit pitch is applied to the collective pairs 125 comprising a plurality of the twisted pairs 120 as shown in fig. 3.

[79] The first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 are successively arranged in counterclockwise direction relative to the first twisted pair 121 which is disposed in the right and upper region as shown in fig 2.

[80] Wherein the pitch p of the first twisted pair 121 is 11.7(± 0.3) mm, the pitch p of the second twisted pair 122 is 10.3(± 0.3) mm, the pitch p of the third twisted pair 123 is 8.6(± 0.3) mm and the pitch p of the fourth twisted pair 124 is 9.4(+ 0.3) mm.

[81] Further, since cross talk among the respective twisted pairs 120 is liable to take place in case the pitches of the first, the second, the third and the fourth twisted pairs 121,

122, 123, 124 are identical or similar with one another, the pitch p of the respective twisted pair 120 is desirably adjusted to be different from one another.

[82] And, the above-specified numerical values are optimal values which are obtained through a plurality of experiments for minimizing the cross talk of the UTP cable.

[83] Wherein, the position of the first twisted pair 121 is not limited to the above- described position, and the arrangement direction of the twisted pairs can be clockwise, however, the twisted pairs must be arranged one after the other relative to the first twisted pair 121 because the pitches p are limited to the above- specified values for the minimization of the cross talk as described in the above.

[84] With regard to the error range of (± 0.3 mm), since it is impossible to manufacture the twisted pairs perfectly at the exact pitch values p in actual processing, the error range included in the first, the second, the third and the fourth twisted pairs 121, 122,

123, 124 means that may happen during actual processing.

[85] The collective pairs 125 is formed by the collection of the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 each of which has the above- specified pitch p, and has collective pitch P in the range of 40mm to 200mm as described in the above.

[86] In case that the collective pitch P of the collective pairs 125 is below 40mm, the length of the entire electric wire 110 is increased due to the small-value of pitch, which results in that the quantity of material needed for manufacturing the cable is increased as well as the decreasing effect of the cross talk among the twisted pair 120 is not so big, whilst in case the collective pitch P of the collective pairs 125 is above 200mm, it is difficult to retain the collective pitch P at its initial value.

[87] Further, a rip-cord 146 can be comprised in the inner part of the sheath 140 so that the outer cover of the sheath 140 can be easily stripped.

[88] The rip-cord 146 which is desirably made of synthetic resin makes the outer cover of the sheath 140 be easily and correctly stripped when UTP cable is placed and by that efficiency of the work can be increased.

[89] Further, the UTP cable according to the present invention comprises the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 which are successively provided in clockwise or counterclockwise direction and each of which is formed by two electric wires twisted with each other helically to define the pitch p; a separator 130 which separates the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 from one another; a collective pairs 125 which includes the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 and the separator 130 and is twisted helically to have a collective pitch P; and a sheath 140 which wraps the collective pairs 125, wherein the collective pitch P is 40mm to 200mm, the pitch p of the first twisted pair 121 is 11.7(± 0.3) mm, the pitch p of the second twisted pair 122 is 8.6(± 0.3)mm, the pitch p of the third twisted pair 123 is 10.3(± 0.3)mm and the pitch p of the fourth twisted pair 124 is 9.4(± 0.3) mm.

[90] Herein, the condition which has the above numerical values is defined as <optimal pitch p condition 2>.

[91] Since cross talk among the respective twisted pairs 120 is liable to take place in case the pitches of the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 are identical or similar with one another, the pitch p of the respective twisted pair 120 is desirably adjusted to be different from one another and the above- specified numerical values are optimal values which are obtained through a plurality of experiments for minimizing the cross talk of the UTP cable.

[92] Since the above- specified UTP cable has the same constitution as that of the previously-described UTP cable except the values of the pitches p of the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124, the detailed description of this UTP cable is replaced by previous description to avoid redundancy.

[93] Further, the UTP cable according to the present invention comprises the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 which are successively provided in clockwise or counterclockwise direction and each of which is formed by two electric wires twisted with each other helically to define the pitch p; a separator 130 which separates the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 from one another; a collective pairs 125 which includes the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 and the separator 130 and is twisted helically to have a collective pitch P; and a sheath 140 which wraps the collective pairs 125, wherein the collective pitch P is 40mm to 200mm, the pitch p of the first twisted pair 121 is 12.0(± 0.3) mm, the pitch p of the second twisted pair 122 is 10.3(± 0.3)mm, the pitch p of the third twisted pair 123 is 8.6(± 0.3)mm and the pitch p of the fourth twisted pair 124 is 9.4(± 0.3) mm.

[94] Herein, the condition which has the above numerical values is defined as <optimal pitch p condition 3>.

[95] Since cross talk among the respective twisted pairs 120 is liable to take place in case the pitches of the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 are identical or similar with one another, the pitch p of the respective twisted pair 120 is desirably adjusted to be different from one another and the above- specified numerical values are optimal values which are obtained through a plurality of experiments for minimizing the cross talk of the UTP cable.

[96] Since the above- specified UTP cable has the same constitution as that of the previously-described UTP cable except the values of the pitches p of the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124, the detailed description of this UTP cable is replaced by previous description to avoid redundancy.

[97] Further, the UTP cable according to the present invention comprises the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 which are successively provided in clockwise or counterclockwise direction and each of which is formed by two electric wires twisted with each other helically to define the pitch p; a separator 130 which separates the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 from one another; a collective pairs 125 which includes the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 and the separator 130 and is twisted helically to have a collective pitch P; and a sheath 140 which wraps the collective pairs 125, wherein the collective pitch P is 40mm to 200mm, the pitch p of the first twisted pair 121 is 12.0(± 0.3) mm, the pitch p of the second twisted pair 122 is 8.6(± 0.3)mm, the pitch p of the third twisted pair 123 is 10.3(±0.3)mm and the pitch p of the fourth twisted pair 124 is 9.4(+ 0.3) mm.

[98] Herein, the condition which has the above numerical values is defined as <optimal pitch p condition 4>.

[99] Since cross talk among the respective twisted pairs 120 is liable to take place in case the pitches of the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 are identical or similar with one another, the pitch p of the respective twisted pair 120 is desirably adjusted to be different from one another and the above- specified numerical values are optimal values which are obtained through a plurality of experiments for minimizing the cross talk of the UTP cable.

[100] Since the above- specified UTP cable has the same constitution as that of the previously-described UTP cable except the values of the pitches p of the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124, the detailed description of this UTP cable is replaced by previous description to avoid redundancy.

[101] Hereinafter, it is shown that the UTP cable according to the present invention can minimize the cross talk under the high speed data transmission condition.

[102] For the exact derivation of the numeric value of the examined example, the numeric values of the first, the second, the third and the fourth twisted pairs 121, 122, 123, 124 of the UTP cable is adjusted to be different from one another (controlling factor), while the numeric values of the other constitutional elements and exterior condition remained unchanged (controlled factor).

[103]

[ 104] Compared example

[105] The UTP cable used in the compared example is Cat. 6 product(refer to fig. 2) manufactured in accordance with the conventional art, the pitch pi of the first twisted pair is set to be 10.9mm, the pitch p2 of the second twisted pair set to be 8.5mm, the pitch p3 of the third twisted pair is set to be 10.3mm, and the pitch pi of the fourth twisted pair is set to be 9. lmm, all of which are almost the same as the values of the above- described <optimal pitch condition 2>.

[106] Further, the first twisted part 121 is placed in the upper and right region, and the second, the third and the fourth twisted pairs 122, 123, 124 are successively placed in the counterclockwise direction relative to the upper and right region, and the collective pitch P of the first, the second, the third and the fourth twisted part 121, 122, 123, 124 is set to be 60mm.

[107] In addition, the sheath 140 is made of polyvinyl chloride(PVC) whose thickness is

0.6mm, and with regard to the separator 130 of the UTP cable which are used here, the separating walls which separate the respective twisted pairs 121, 122, 123, 124 from one another have identical thickness with one another, and no particular structure is provided in the walls.

[108] Using the UTP cable manufactured as described in the above, signal was transmitted by the UTP cable of 100m with the frequency varied from IMHz to 500 MHz according to the draft standard of IEEE 802.3, and the data loss resulted from the cross talk was measured.

[109] The measured result is shown fig. 4, wherein interference standard provided under the IEEE 802.3 is illustrated in solid line, while the measured results of the present compared example are shown in wave patterns. [HO]

[111] Example

[112] In the UTP cable used in the embodiment according to the present invention, the pitches pi, p2, p3, p4 of the first, the second, the third, and the fourth twisted pair are set to satisfy <optimal pitch condition 2>, and the first twisted part 121 is placed in the upper and right region, and the second, the third and the fourth twisted pairs 122, 123, 124 are successively placed in the counterclockwise direction relative to the upper and right region, and the collective pitch P of the first, the second, the third and the fourth twisted part 121, 122, 123, 124 is set to be 60mm.

[113] Further, the sheath 140 is made of polyvinyl chloride(PVC) whose thickness is 0.6mm, and regarding the separator 130 of the UTP cable used here, the separating walls which separate the respective twisted pairs 121, 122, 123, 124 from one another have identical thickness with the previously describe compared example, and no particular structure is provided in the walls.

[114] In this regard, for the sake of the exact measurement of the experimental values, only the pitch p is set to be different from that of the above-described compared example.

[115] Using the UTP cable manufactured as described in the above, signal was transmitted by the UTP cable of 100m with the frequency varied from IMHz to 500 MHz according to the draft standard of IEEE 802.3, and the data loss resulted from the cross talk was measured.

[116] The measured result is shown fig. 5, wherein interference standard provided under the IEEE 802.3 is illustrated in solid line, while the measured results of the present embodiment are shown in wave patterns.

[117] Referring to fig.4, the UTP cable manufactured according to the conventional art shows a result that the second twisted pair and the third twisted pair exceed the standard values in the band of 200 ~ 300MHz in the cross talk measuring experiment.

[118] On the contrary, referring to fig.5, the UTP cable manufactured according to the embodiment of the present invention shows a result that the standard value is satisfied across the entire frequency band in the cross talk measuring experiment.

[119] In addition, a plurality of tests satisfying <optimal pitch condition 1>, <optimal pitch condition 3>, and <optimal pitch condition 4> have been performed under the same test condition as that of the above, wherein similar results were obtained in the compared example and the embodiment as well.

[120] Although the present invention has been described with reference to the specified compared examples and the embodiments in the above, the idea of the present invention is not limited to the above described matters and various change and modification can be easily made within the equivalent scope of the present invention and the following claims by the ordinary- skilled person of the art.