[DESCRIPTION] [InventionTitle] FILTER STRUCTUREFORMASK [Technical Field] i> The present invention relates to a filter structure for amaskutilized in daily life and industrial sites, and more particularly to a filter structure for a mask, in which the mask is configured as an air inhalation unit inside a mask body and an air exhalation unit outside the mask body are coupled to one another, wherein the air inhalation unit includes a pair of inhalation filter cases which is configured as an inner inhalation filter case and an external inhalation filter case are combined with one another from the mask body; wherein the inner inhalation filter case located at the inside of the mask body includes: a non-weave fabric pocket including bio- ceramic particles in a diameter range of 0.5 ~2mm, which produce negative ions, a first to fifth folded charcoal fabric made of 100% charcoal which has functions of antibiosis, deodorization, smoke-proof, and dust-proof, and a non-weave fabric for fixing the charcoal fabric thereto and for performing a dust proof function, in which the non-weave fabric pocket, the first to fifth folded charcoal fabrics and the non-weave fabric are sequentially stacked from the direction of a wear's face. Therefore, the mask has functions of antibiosis, deodorization and dust-proof, as the external inhalation filter case is combined with the inner inhalation filter case. [BackgroundArt] <2> In general, dust or noxious gas generated in the working sites, and fine dust or dust, etc., produced as people act in their daily lives, include various components. Some of them can be harmful to the health. Namely, when people inhale air including such harmful components, they can easily get a disease of the respiratory organ. In order to prevent such problems, masks to be used in working sites, such as a durst-proof mask and an anti-gas mask, have been successively developed. A prior art mask includes an inner case and an external case, which are melted by an ultrasonic method and then coupled to one another. Here, the inner case forms an. air inhalation hole therein, which is penetrated to the inside of the mask body. Also, the external case forms an air exhalation hole therein and includes charcoal particles, etc., therein. Even though such a prior art mask is designed such that the inner and external cases are melted and coupled to one another, if there is a gap between the inner and the external cases due to incomplete coupling, a wearer may inhale noxious gases through the gap. Therefore, the prior art masks cannot completely prevent noxious gases from filtering. Also, the prior art mask has still disadvantages in that, since only charcoal and/or clothes, etc., are used for a filter, they cannot filter suchnoxious materials. [Disclosure] [Technical Problem] <3> Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a filter structure for a mask which is capable of filtering noxious material and providing purified air flowing from the outside to the inside thereof, in which thepurified air includes negative ions useful to the health. <4> It is another object of present invention to provide a filter structure for a mask, which is capable of effectively providing functions, such as antibiosis, deodorization and dust-proof. <5> It is yet another object of present invention to provide a filter structure for a mask which is designed such that an external inhalation filter case and an inner inhalation filter case are separably coupled to one another, thereby replacing filters imbedded in the inhalation filter case withnew ones. [Technical Solution] <6> In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a filter structure for a mask, in which the mask is configured as an air inhalation unit inside a mask body and an air exhalation unit outside the mask body are coupled to one another, wherein: the air inhalation unit inputting external air includes a pair of inhalation filter cases which are shaped as a cylinder and configured as an inner inhalation filter case and an external inhalation filter case are correspondinglycombinedwithone another from themask body; wherein the inner inhalation filter case 14 located at the inside of the mask body includes: a non-weave fabric pocket 18 including bio-ceramic particles 20 in a diameter range of 0.5 ~2mm, which produce negative ions, first to fifth folded charcoal fabric 22 made of 100% charcoal which has functions of antibiosis, deodorization, smoke-proof, and dust-proof, and a non-weave fabric 24 fixing the charcoal fabric thereto and performing a dust proof function, in which the non-weave fabric pocket, the first to fifth folded charcoal fabrics and the non-weave fabric are sequentially stacked from the direction of a wear's face. Here, the non-weave fabric is fixedly supported by the external inhalation filter case 16 located outside the maskbody 10. <7> In accordance with another aspect of the present invention, there is provided a filter structure for a mask, in which an inner inhalation filter case 14 of an inhalation filter case 12, which is shaped as a cylinder and correspondingly coupled to one another in a pair from the inside and the outside, includes a receivingprotrusion 28 formed at the inner circumference thereof. Here, the external inhalation filter case 16 correspondingly coupled to the inner inhalation filter case includes an insertion protrusion 30 formed the outer circumference thereof. Therefore, they are elastically insertedby an external force and closely coupled to one another. <8> Preferably, the bio-ceramic particles are sericite particles in a diameter range of 0.5 ~ 2mm. [Descriptionof Drawings] <9> The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunctionwith the accompanying drawings, inwhich: <io> Fig. 1 is a view illustrating a mask according to the present invention; <ii> Fig. 2 is a cross-sectional view illustrating an inhalation filter case of a filter structure for a mask according to the present invention, taken along lineA-A inFig. 1; <12> Fig. 3 is an exploded perspective view illustrating an inhalation filter case of a filter structure for a mask according to the present invention, takenalong lineB-B inFig. 1; <13> Fig. 4 is a cross-sectional view illustrating an exhalation hole of a prior art mask; and <14> Fig. 5 is an exploded perspective view illustrating an exhalation hole of aprior art mask. [Best Mode] <15> With reference to the attached drawings, the filter structure for a mask according to the present invention is described in detail below. <16> Fig. 1 is a view illustrating a mask according to the present invention. Fig. 2 is a cross-sectional view illustrating an inhalation filter case of a filter structure for a mask according to the present invention, taken along line A-A in Fig. 1. Fig. 3 is an exploded perspective view illustrating an inhalation filter case of a filter structure for a mask according to the present invention, taken along line B-B in Fig. 1. Fig. 4 is a cross-sectional view illustrating an exhalation hole of a prior art mask. Fig. 5 is an exploded perspective view illustrating an exhalation hole of a prior art mask. <i7> As shown inFigs. 1 to 3, the filter structure for a mask according to the present invention includes an inner inhalation filter case 14 through which air is flown in the inside of the mask, in which the inner inhalation filter case 14 is shaped as a cylinder and located at the inside of a mask body 10, and an external inhalation filter case 16 through which air is flown in the inside of the mask, in which the external inhalation filter case 16 is shaped as a cylinder and located outside the mask body 10. Here, the external inhalation filter case 16 is correspondingly coupled to the inner inhalation filter case 14. <i8> The inner inhalation filter case 14 includes an air inhalation unit 31 which is shaped as being of a radial type or a mesh type to flow air therein and integratedly formed therein, in which a part of the air inhalation unit 31 is contactedby awearer's front face. <19> The inner inhalation filter case 14 shaped as a cylinder is implemented with an open hole at one end thereof, in which a non-weave fabric pocket 18, first to third folded charcoal fabrics 22, and a non-weave fabric 24, which are separated therefrom. Here, the non-weave fabric pocket 18, in which bio- ceramic particles 20 in a diameter range of 0.5 ~2mm, preferably, sericite particles 45 are included, is imbedded in the open hole, such that negative ions are generated from the inside of the inner inhalation filter case 14, in which the wearer's face is contacted. The first to third folded charcoal fabrics 22 having functions, such as antibiosis, deodorization, smoke-proof, dust-proof and protection from poison gas, are imbedded in the open hole. Also, the non-weave fabric 24 performs a dust proof function. On the other hand, the charcoal fabrics 22 canbe implementedby first to fifth folds or a pluralityof folds. <20> Also, the one end at which the open hole is formed can be inserted and separatedby various filters and forms a receiving protrusion 28 on the inner circumference thereof. <2i> On the other hand, the external inhalation filter case 16 correspondingly coupled to the inner inhalation filter case 14 forms an insertion protrusion 30 on the outer circumference at one end thereof. Here, the insertion protrusion 30 is shaped as a cylinder such that the outer inhalation filter case 16 is correspondingly coupled to the inner inhalation filter case 14. Also, the external inhalation filter case 16 forms a rising unit 26 at which the mask body 10 is located, in which the rising unit 26 is adjacent to the insertion protrusion 30. The external inhalation filter case 16 integratedly forms a radial type or a mesh type air inhalation cap 32 at the other end thereof. <22> Therefore, the mask as configured above is assembled such that: a non- weave fabric pocket 18 including bio-ceramic particles 20 of a predetermined size, the first to third folds charcoal fabric 22 having functions of antibiosis, deodorization, dust-proof, smoke-proof and protection from poison gas, and a non-weave fabric 24 functioning dust-proof, are sequentially inserted in the inner inhalation filter case 14 shaped as a cylinder, from the inside facing a wear's front face. After that, the mask body IO is inserted into the rising unit 26 of the external inhalation filter case 16, and then the insertion protrusion 30 is pressed such that the insertion protrusion 30 is elastically inserted into the receiving protrusion 28. Namely, such pressure is applied thereto such that the mask body 10 located at the rising unit 26 of the external inhalation filter case 16 is pressedly sealed. <23> Even though the filters included in the inner inhalation filter case are semi-permanent, they can be replaced with new ones as occasion demands. Namely, when the filters are replaced, the inner inhalation filter case 14 and the external inhalation filter case 16 of an inhalation filter case 12 are pressed such that the filter can be separated as the reverse sequence different from the above mentioned sequence. <24> Such a mast having a filter structure according to the present invention is operated such that air flown in the radial type or mesh type air inhalation unit 31 of the external inhalation filter case 16 is firstly passed through the non-weave fabric 24 to perform dust-proof, secondly passed through the first to third folded charcoal fabrics 22 to perform antibiosis, deodorization, dust-proof, smoke-proof and protection from poison gas, and then thirdly passed through the bio-ceramic particles 20, preferably, sericite particles 45, which generates negative ions, to produce purified air. Therefore, the wearer can inhale the purified air through the radial type or mesh type air inhalation unit 31 of the inner inhalation filter case 14. An active carbon fabric is generally produced such that, wood is processed to form a predetermined form; the predetermined wood form is chemically processed; the chemicallyprocessed wood is carbonized, activated, washed, and dried. Carbonization temperature is within a range of 180°C to 400°C and activation is processed at 600°C to 1000°C in CH2Cl2 or vapor. The

charcoal fabric 22 used in the present invention is made of black oak charcoal, which is produced such that: black oak of 100% is carbonized to produce charcoal of 100%; the charcoal of 100% is finely pulverized at a relatively high temperature of 1000°C ~1500°C; a_nd the finely pulverized charcoal is passed between upper and lower rollers, while it is sprayed by high temperature steam of 500°C ~1000°C. <25> A fabric made of 100% black oak charcoal had advantages in that, since it has a relatively large surface area and forms a. fine hole layer therein, its adsorption force, adsorption capacity and deodorization force are relatively large and also it is relatively light. Also, the bio-ceramic particles 20 producing negative ions are implemented with sericite particles 45 and have a range of diameter, preferably, 0.5~2mm. Radiations of negative ions or energy, etc., regarding sericite particles 45, is tested by various methods, such as nuclear magnetic resonance wave analysis, in which the test result is demonstrated andpubliclywell known. <26> As shown in Figs. 4 to 5, the mask exhalation device 33 includes an inner exhalation case 36 and the external exhalation case 38 of the mask body 10. Here, the inner exhalation case 36 and the external exhalation case 38 are shaped as a cylinder. Also, the inner exhalation case 36 and the external exhalation case 38, located at the inside and the outside of the mask body 10, respectively, are correspondingly coupled to one another. One side of the inner exhalation case 36 is formed as being of a radial type or mesh type such that air exhaled by the wearer can be flown out;. Other side of the inner exhalation case includes a receiving protrusion 28' at the inner circumference thereof such that the external exlialation case 38 can be inserted thereto, and forms a groove 42 at the cemter thereof, in which the groove 42 fixes a plate film 40 made of elastic material which is harmless to the human body thereto. Here, the plate film 40 discharges air exhaled by the wearer to the outside and intercepts air from the oαtside to the inside. <27> On the other hand, one side of the external case 38 includes an insertion protrusion 30' shaped as a cylinder at the outer circumference thereof, and a rising unit 26' at a portion where the insertion protrusion 30' is contacted, in which the rising unit 26' is located by the mask body 10. <28> Other side of the external exhalation case 38 is integratedly formedby a radial type or mesh type cap 34 for an air exhalation device. When the air exhalation device is assembled to the mask body 10, using the method as described in Figs. 1 to 3, the air exhalation device is closely attached to the mask body such that the receiving protrusion 28' of the inner exhalation case 36 and the insertion protrusion 30' of the external exhalation case 38 are coupled to one another. There is a plate film 40, which is fixedly inserted between the inner and the external exhalation cases, in order to intercept an external air and discharge air exhaled by the wearer to the outside. Here, the plate film 40 is shaped as circular and is not harmful to men. Also, the plate film 40 has elasticity. The plate film 40 includes a fixing protrusion 44 protrudently formed at the center thereof, in which the fixing protrusion 44 is insertedly coupled to a groove 42 formed at the center of the inner exhalation case. Since the plate film 40 is elastic material which is not harmful to men, it can be safely separated. Reference numeral 1 denotes a belt used when the wearer wears the mask, in which the belt is generallyused as it hangs ears. [Industrial Applicability] <29> The filter structure of a mask according to the present inventionhas advantages in that since 100% charcoal fabric and bio-ceramic particles, which generate negative ions or radiate energy, are used, it has functions of antibiosis, deodorization, dust-proof and protection from poison gas to effectively purify air, comparing with the prior art mask. Also, the filter structure of a mask according to the present invention has advantages in that, it can be semi-permanentIy used, or it can be replaced with new one as occasiondemands. <30> Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.