baber/WOPTO huggingface dataset:
Patent KR-20010008088-A (KR)
Title: Method for constructing automatic sluice gate
Inventor: HAN SANG KWAN
IPC: E02B7/20
Filed: 2000-11-07
Abstract: PURPOSE: A constructing method of an automatic sluice gate is provided to automatically open or close the sluice gate by operating a cylinder to open or close both upper and lower parts of a water storage part, thereby making the draining smooth in the lower part of the water storage part and preventing red water and green water phenomena. CONSTITUTION: A construction method of an automatic sluice gate includes a pair of walls(1,1) constructed by a predetermined distance at both sides of a watercourse, a rotation element(2) having a hollow supporting shaft straightly fixed on an inner surface of one of the walls, a rotation case element(22) slidably coupled at an outer periphery of the supporting shaft(21), a pinion(23) fixed to the rotation case element, and a rack(25) engaged with the pinion and operating by an opening and closing cylinder(24), and a sluice gate main body(3) arranged between the walls and fixed to the rotation element at front end, wherein the sluice gate main body moves by operating the opening and closing cylinder to open or close the watercourse between the walls.
Patent KR-20020036363-A (KR)
Title: Device for cooling strip in continuous annealing furnace
Inventor: HAN JIN
IPC: C21D1/00
Filed: 2000-11-09
Abstract: PURPOSE: An apparatus for rapidly cooling a strip in a continuous annealing furnace is provided which selectively rapidly cools the strip passing through the annealing furnace at need so as to prevent deterioration of productivity by maintaining a normal line speed, thereby prevents generation of facility accidents. CONSTITUTION: In a continuous annealing line comprising a continuous annealing furnace in which annealing is performed, a cooling zone for cooling a strip(150) passing through the annealing furnace and a dryer for removing cooling water on the surface of the strip, the apparatus for rapidly cooling the strip(150) in the continuous annealing furnace comprises an auxiliary cooling part comprising housings(10) in which slits(11) are formed from the side surface to the central part so that the strip makes its way into the slits(11), and which are formed at both sides of the strip, injection pipes(12) which are installed at upper and lower parts of the housings to inject cooling water onto the strip(150) passing through the slits(11), injection nozzles formed on the injection pipes(12), and a cooling water supply means which is connected to the injection pipes through one side surfaces of the housings(10) to supply cooling water; and a driving part comprising a pair of rail members(30) which are installed in a width direction of the strip on the bottom of the facility between the cooling zone and the dryer, moving members(31) which are installed along each of the rail members(30) at both sides of the strip so that the moving members(31) are moved to the strip side, and onto the upper parts of which the housing are fixed, a driving cylinder(32) which is installed in a width direction of the strip(150) between the rail members(30), and connected to one sides of the moving members(31) to move the moving members, and an interlocking means which symmetrically moves the two housings(10) to equal distances according to expanding or contracting operation of the driving cylinder(32).
Patent KR-20010025238-A (KR)
Title: Preparation of 2,4-halogen substituted biphenyl derivatives
Inventor: HAM JAE YONG
IPC: C07C25/00
Filed: 2000-11-14
Abstract: PURPOSE: A process for preparing the title compounds by reaction of 2-halogen aniline with a halogen molecular in the presence of a phase transition catalyst and an organic solvent and then the obtained half product with benzene and sodium nitrite or isoamyl nitrite is provided which can mass-produce biphenyl derivatives substituted with halogen at the 2, 4-position at low cost. CONSTITUTION: The subject biphenyl derivatives of formula 1 substituted halogen at the 2, 4-position are prepared by a process consisting of: preparing aniline acid salt derivatives substituted with halogen at the 2, 4-position of formula 3 by reaction of 2-halogen aniline of formula 2 with halogen in the presence of a phase transition catalyst and an organic solvent; and reacting the obtained aniline acid salt derivatives substituted with halogen at the 2, 4-position with sodium nitrite or isoamyl nitrite and benzene in the presence of an acid aqueous solution. In formula, X1, X2, X are each independently halogen.
Patent KR-20020039799-A (KR)
Title: method for manufacturing corrosion-preventing drain channel
Inventor: PARK HYO GI
IPC: E03F3/04
Filed: 2000-11-22
Abstract: PURPOSE: A method for preparing a drainage port useful for preventing corrosion is provided to prevent the port from being released at inner side of the drainage but to be retained closely to concrete wall body of the drainage. CONSTITUTION: The method comprises steps of forming outer concrete portion(2) by introducing concrete; injecting a specific, structural material(4) for preventing release of the drainage port to inner side of the outer concrete portion well before the inner side is cured by means of common sprayer; and spraying polyethylene material at a desired thickness over the structural material half-attached to the inner side to form a water-resistant inner layer(6). The inner layer(6) is not removed because the polyethylene material is filled into spaces of the structural material and is cured.
Patent KR-20020040091-A (KR)
Title: Slurry for chemical mechanical polishing and manufacturing method of copper metal interconnection layer using the same
Inventor: HA SANG ROK
IPC: C23F3/06
Filed: 2000-11-23
Abstract: PURPOSE: A slurry for chemical and mechanical polishing and a method for manufacturing copper interconnection using the same are provided to prevent a contamination and a scratch by using a slurry for a CMP(Chemical Mechanical Polishing). CONSTITUTION: Recess regions are formed on an interlayer dielectric(20) using a photolithography. At this time, the recess regions are trenches(22). A barrier(24) made of tantalum, tantalum nitride, titanium, or titanium nitride and a copper seed layer are sequentially formed on the entire surface of the resultant structure along the step coverage. Then, a CMP(Chemical Mechanical Polishing) is performed on the resultant structure using a slurry without an abradant, thereby preventing a contamination and a scratch. After depositing a copper plating layer(28), the copper plating layer(28) and the barrier(24) are removed to form buried metal interconnections using another CMP.
Patent KR-20010077932-A (KR)
Title: A semiconductor integrated circuit device and a method of manufacturing thereof
Inventor: HIGUCHI MITSUHIRO
IPC: H01L29/423
Filed: 2000-11-27
Abstract: PURPOSE: To reduce irregularity of threshold voltage of a micronized MISFET. CONSTITUTION: A gate electrode 9a of the MISFET (Q1)is formed on a substrate 1 of an active region L whose periphery is regulated by an element isolating trench 2 and stretches from one end to the other end of the active region L intersecting it. The gate electrode 9a whose gate length in a boundary region between the active region L and element isolating trench 2 is greater than that in the central part of the active region L is constituted of an H-shaped plane pattern as a whole. The gate electrode 9a covers the whole of one edge along the gate lengthwise direction of the boundary region between the active region L and element isolating trench 2 and covers a part of two edges along the gate width direction.
Patent KR-20010070273-A (KR)
Title: Semiconductor device
Inventor: AKASAKI HIROSHI
IPC: G11C7/10
Filed: 2000-12-07
Abstract: PURPOSE: To increase speed of memory operation by such access specification that a column address strobe signal is varied with a rate of one time per plural cycles of a clock signal. CONSTITUTION: A column address strobe signal CAS varied with a period of plural times of a clock signal period is inputted to memory blocks MBK0-MBKn, for each cycle in which a column address signal CASADR is varied, plural serial data read out from a memory cell array 10 and converted by a parallel/ serial conversion circuit 21 synchronizing with a clock signal cycle is outputted from a memory block, also, parallel data inputted to a memory block synchronizing with a clock signal cycle and converted by a serial/parallel conversion circuit 25, and parallel data is written in a memory cell array. Operation speed of memory operation can be increased by such access specification that a column address strobe signal is varied with a rate of one time per plural cycles of a clock signal.
Patent KR-20020044972-A (KR)
Title: An automotive double folding tail gate
Inventor: PYO HA GEUN
IPC: B60J5/10
Filed: 2000-12-07
Abstract: PURPOSE: A double folding gate of a vehicle is provided to load and unload cargo conveniently by opening the load compartment with folding a tailgate inward, and to improve convenience by loading cargo in the limit space efficiently. CONSTITUTION: A double folding gate for a vehicle is composed of a lid panel(1) fixed and supported in a vehicle floor through a turning unit(10) pulled back in the vehicle, and a glass(2) having the lower part folded by a folding unit(20) formed in the upper part of the lid panel, and the upper part mounted and separated from a roof panel through a locking unit(30). The glass is folded in the lid panel with the folding unit in moving the glass to the lid panel, and contained in the lid panel with turning a hinge arm(21) of the folding unit around a turning pin. The loading compartment is opened with pushing the lid panel including the glass into the vehicle. Cargo is loaded and unloaded conveniently in the limit space with opening the loading compartment by folding the tailgate.
Patent KR-20020047498-A (KR)
Title: High resolution lens and information recording devide using it
Inventor: OH HYEONG YEOL
IPC: G11B7/1387
Filed: 2000-12-13
Abstract: PURPOSE: A super resolving power lens is provided to record near field optical information without another condenser lens, to prevent deterioration of a condensing capacity caused by aberration, and to be curved on the bottom, thereby reducing a risk of being collided with a surface of a recording medium. CONSTITUTION: An upper surface(91) of a lens is a plane, and a lower surface thereof is curved. An edge(92) of a lower surface of the lens is curved, and a center(93) thereof is a plane. The lower surface is coated with a reflective material. A central peak of the lower surface is not coated with the reflective material. The center where a lens focus is formed is formed lower than the lower surface of the lens. An optical system using a near field is located closely to a measured target or a recording medium. An area where an optical focus of the optical system is formed is exposed on the air.
Patent KR-20020052358-A (KR)
Title: The FED's black matrix and the making method of the FED's black matrix
Inventor: JIN IL SEOP
IPC: H01J1/30
Filed: 2000-12-26
Abstract: PURPOSE: A black matrix of a field emission display and a forming method thereof are provided to avoid separation of joint of spacers and thus falling down of spacers and improve light and darkness. CONSTITUTION: To form a black matrix of a field emission display, a CrOx layer(410) is deposited of 500-10000Å on an anode flat substrate(400) by sputtering. An Al layer(420) of 500-10000Å is deposited on the CrOx layer(410) by sputtering. A photo resist(430) is coated over the Al layer(420) by a spin-coater. After arranging a Chromium mask(440) over the photo resist(430), the Al layer(420) is patterned by etching in AL12 solution and then the CrOx layer(410) is patterned by etching in CR7 solution. After etching, the photo resist(430) is removed. Frit glass is arranged on the black matrix in a dot type or a stripe type. The spacers are arranged on the frit glass and adhered to the Al layer(420) of the black matrix by thermal processing.
Patent KR-20020053906-A (KR)
Title: Compound punch press
Inventor: KIM SU GEUN
IPC: B21D37/08
Filed: 2000-12-26
Abstract: PURPOSE: A composite punch press apparatus is provided to decrease the number of processes for forming panel material by enabling both piercing and flanging processes of the panel material to be simultaneously carried out. CONSTITUTION: A composite punch press apparatus comprises a lower steel member(3), an upper pad(7), a flanging steel member(11) and a piercing steel member(15). The lower steel member(3) is mounted on a lower die(5), and has a flange forming surface(1) at one side of the top surface thereof. The upper pad(7) is provided above one side of the top surface of the lower steel member(3). The flanging steel member(11) is mounted to an upper die(13) at the side of the upper pad(7). The flanging steel member(11) flanges panel material along a flange forming surface(1) formed in the lower steel member(3). The piercing steel member(15) is mounted to the bottom surface of the flanging steel member(11), and is interlocked with the upper die(13) to pierce the panel material at one edge of the lower steel member(3).
Patent KR-20020056355-A (KR)
Title: Method of manufacturing a flash memory device
Inventor: KIM BONG GIL
IPC: H01L29/788
Filed: 2000-12-29
Abstract: PURPOSE: A method for fabricating a flash memory device is provided to improve uniformity of an oxide layer in a peripheral circuit region by sufficiently performing a pre-cleaning process regarding a gate oxide layer, and to improve a cell characteristic by making a cover polysilicon layer protect a dielectric layer in a cell region. CONSTITUTION: A semiconductor substrate(31) is prepared in which the peripheral circuit region and the cell region are defined. A tunnel oxide layer(33a) and the first polysilicon layer(34) for a floating gate are formed in the cell region. A dielectric layer(35) is formed. The second polysilicon layer(37) for protecting and planarizing the dielectric layer is formed and etched back to planarize the upper portion of the second polysilicon layer. The second polysilicon layer and the dielectric layer in the peripheral circuit region are removed to expose the surface of the substrate by an etch process. A gate oxide layer(33b) for high voltage and a gate oxide layer(33c) for low voltage are formed in the peripheral circuit region while the upper portion of the second polysilicon layer in the cell region is oxidized to form a polysilicon oxide layer. The third polysilicon layer for a gate electrode is formed in the peripheral circuit region. The third polysilicon layer and the polysilicon oxide layer in the cell region are eliminated. A top polysilicon layer(38) and a tungsten silicide layer(39) are sequentially formed and patterned.
Patent KR-20020058280-A (KR)
Inventor: LEE WON CHANG
IPC: H01L21/335
Filed: 2000-12-29
Abstract: PURPOSE: A fabrication method of a transistor having double gates is provided to improve an accuracy of alignment between an upper gate and a lower gate. CONSTITUTION: A first gate electrode is formed on an SOI(Silicon On Insulator) substrate(41) stacked sequentially a lower silicon layer, a buried oxide and an upper silicon layer. After forming an interlayer dielectric(57) on the resultant structure, a silicon substrate(59) is bonded to the interlayer dielectric. The resultant structure is reversed. After removing the lower silicon layer, the buried oxide is selectively etched. A second gate electrode(63) is formed on the exposed upper silicon layer. Source and drain regions(65) are formed in the upper silicon layer.
Patent KR-20010021785-A (KR)
Title: 절연과 냉각기능의 콜로이드 액
IPC: H01B3/20
Filed: 1998-07-14
Abstract: 본 발명은 향상된 절연 및/또는 냉각 기능을 가진 콜로이드 액에 관한 것이다.  본 발명의 구체예는 담체액과 비금속 입자의 분산상으로 구성된 콜로이드로서 포화 자화가 약 50 Gauss 보다 작은 것을 특징으로 한다.   본 물질은 변압기와 같은 고전압 장치를 포함한 전자기적 장치를 절연 및/또는 냉각하기 위하여 사용된다.
Patent KR-20010023503-A (KR)
IPC: H01L21/02
Filed: 1998-08-27
Abstract: The invention relates to a transport system for conveying products during the production process, especially integrated semiconductor products, to facilities inside a building, where they are submitted to factory processing. The invention is characterized in that the transport system and the machining facilities are separated by a floor and that the supply process from the transport system to the machining center is made through opening in said floor. Such a system is advantageously built separately from the machining center, resulting in a significant increase of the supply pace. It enables any place in the plane of the system to be reached and to be accessed any time in case of failure. It also provides with the possibility to significantly reduce the complexity of the driving software.
Patent KR-20010023614-A (KR)
Title: 웜기어로 구성된 파워 스티어링
IPC: F16H55/24
Filed: 1998-08-28
Abstract: 본 발명은 파워 스티어링 시스템의 변속기에서 웜(8)과 웜휠(10) 사이에 존재하는 백래쉬와 자유 유동을 제거하기 위한 장치에 관한 것이다. 웜(8)은 전기모터(4)로부터의 출력축(6)에 제공되고 휭은 다른 축(9)(스티어링 컬럼)에 제공된다. 휠은 하우징(1)에 대하여 고정되고, 웜은 적어도 제 1 및 제 2 지지 조립체(100, 200)를 통하여 하우징에 대하여 고정된다. 제 1 지지 조립체(100)는 모터(4)로부터 원격한 출력축(8)의 단부에 제공되고 출력축과 웜기어의 방사상 위치를 조절토록 회전될 수 있는 편심부싱(101)으로 구성된다. 제 2 지지 조립체(200)는 출력축(6)의 회전방향 운동을 허용한다. 제 1 지지 조립체(100)는 자유 유동량을 조절하기 위하여 수동으로 회전되거나 스프링력 하에 자동으로 회전될 수 있다.
Patent KR-20010023838-A (KR)
IPC: A61P19/08
Filed: 1998-09-04
Abstract: 본 발명은 신규 PGF 유사체를 제공한다.  특히, 본 발명은 하기 일반식의 구조를 갖는 화합물에 관한 것이다: 
     
       
     
     여기에서, R 1 , R 2 , R 3 , R 4 , X 및 Z는 정의된 바와 같다. 
     본 발명은 또한 상기식의 광학 이성질체, 부분입체 이성질체 및 거울상 이성질체, 그리고 그의 약학적으로 허용가능한 염, 생가수분해가능한 아미드, 에스테르 및 이미드를 포함한다. 
     본 발명의 화합물은 골 장애 및 녹내장과 같은 다양한 질병과 증상을 치료하는데 유용하다.   따라서, 본 발명은 또한 이들 화합물을 함유하는 약학 조성물을 제공한다.   더나아가 본 발명은 상기 화합물 또는 이를 함유하고 있는 조성물을 사용하여  골 장애 및 녹내장을 치료하는 방법을 제공한다.
Patent KR-20010033264-A (KR)
Title: 피리딘 아미드 및 클로로탈로닐 기재의 살진균제 혼합물
IPC: A01N43/40
Filed: 1998-12-15
Abstract: 본 발명은 활성 성분으로서 a) 하기 화학식 I의 아미드 화합물 및 b) 하기 화학식 II의 화합물을 함유하는 살진균제 혼합물에 관한 것이다.  활성 성분들은 상승 작용 유효량으로 제공된다. 
     〈화학식 I〉 
     A-CO-NR 1 R 2   
     〈화학식 II〉 
     
       
     
     상기 식 중, 
     A는 아릴기이거나, O, N 및 S로부터 선택되는 1 내지 3개의 헤테로 원자를 갖는 방향족 또는 비방향족의 5 또는 6원 헤테로고리이며, 아릴기 또는 헤테로시클릭 화합물은 임의로 알킬, 할로겐, CHF 2 , CF 3 , 알콕시, 할로알콕시, 알킬티오, 알킬술피닐 및 알킬술포닐로부터 서로 독립적으로 선택되는 1, 2 또는 3개의 치환체를 가질 수 있고, 
     R 1 은 수소 원자를 나타내고, 
     R 2 는 알킬, 알케닐, 알키닐, 알콕시, 알케닐옥시, 알키닐옥시, 시클로알킬, 시클로알케닐, 시클로알킬옥시, 시클로알케닐옥시, 페닐 및 할로겐으로부터 서로 독립적으로 선택되는 1, 2 또는 3개의 치환체를 임의로 함유하는 페닐 또는 시클로알킬기이며, 지방족 및 지환식 라디칼은 부분적으로 또는 전부 할로겐화될 수 있고(있거나) 지환식 라디칼은 1 내지 3개의 알킬기로 치환될 수 있으며, 페닐기는 1 내지 5개의 할로겐 원자 및(또는) 알킬, 할로알킬, 알콕시, 할로알콕시, 알킬티오 및 할로알킬티오로부터 서로 독립적으로 선택되는 1 내지 3개의 치환체를 가질 수 있으며, 아미드계 페닐기는 1개 이상의 알킬기로 임의로 치환되고(되거나) O 및 S로부터 선택되는 헤테로 원자를 가질 수 있는 포화 5원 고리와 임의로 축합된다.
Patent KR-20010040597-A (KR)
Title: 캡슐화된 표면 파 구성요소 및 이를 위한 집합적 제조 방법
IPC: H03H9/25
Filed: 1999-12-07
Abstract: 본 발명은 새로운 형태의 캡슐화된 표면 파 구성요소들과 그러한 구성요소들을 제조하기 위한 집합적 방법에 관한 것이다.  상기 구성요소는 외부로부터 상기 표면 파 장치의 전기적 연결을 보증하도록 상기 기판 표면의 표면 파 장치와 상기 캡슐화된 케이스를 포함하며, 상기 캡슐화된 케이스는 상기 기판이외에, 상기 기판상에 위치되며 적어도 상기 표면 웨이브 장치의 액티브 표면에서 국부적으로 오목한 제 1 층과 상기 제 1 층/인쇄 배선 어셈블리를 통한 도전성 비어 홀들과 제 1 층 전체를 커버하는 인쇄 배선을 포함한다.
Patent KR-20010034541-A (KR)
Title: 광정보 기록장치 및 방법, 광정보 재생장치 및 방법,광정보 기록재생장치 및 광정보 기록매체
IPC: G11B7/09
Filed: 1999-02-26
Abstract: 본발명은 홀로그래피를 이용한 정보의 다중기록 또는 재생을 위한 광학계를 소형으로 구성할 수 있게 한다. 
     광정보 기록 재생장치의 픽업(11)과 광원 장치(25)에서 출사된 레이저광을 공간광변조기(18)에 의해 기록하는 정보에 대응해서, 공간적으로 변조해서 정보광을 생성하고, 또한 광원장치(25)로부터 출사된 레이저광을 위상공간 광변조기(17)에 의해 위상을 공간적으로 변조하고 위상이 공간적으로 변조된 기록용 참조광을 생성한다. 정보광 및 기록용 참조광은 서로 상이한 위치에서 수속하도록 광정보 기록매체(1)에 조사되고, 홀로그램층(3)에, 반사막(5)에 의해 반사된 정보광 및 기록용 참조광의 위치결정은 어드레스ㆍ서보에어리어(6)에 기록된 정보에 의거해서 행한다.
Patent KR-20010041332-A (KR)
Title: 정적 파워가 제로(0)인 메모리 디코더
IPC: G11C7/06
Filed: 1999-12-15
Abstract: 본 발명은 동적 전류를 사용하여 메모리 셀의 도전 상태를 감지하는 메모리 셀 디코더에 관한 것이다. 디코더는 전압 소스로부터 예비 충전된 감지 회로를 포함한다. 감지 회로가 전압 소스에서 분리되고 메모리 셀이 액세스 스위치를 통해 접지되면, 메모리 셀이 도전 상태인 경우에는 감지 회로가 방전되고, 메모리 셀이 도전 불능 상태인 경우 그 충전 상태가 유지된다. 감지 회로는 감지 회로가 방전되는지 방전되지 않는지의 여부에 따라 메모리 셀의 도전 상태를 나타내는 신호를 출력한다. 저주파수에서 동작할 수 있도록, 약한 피드백 트랜지스터는 감지 회로를 최초로 충전된 이후에 충전된 상태로 유지하며, 메모리 셀에 접속된 후에 메모리 셀이 도전 불능 상태에 놓인 경우 출력 신호를 유지함으로써 회로 누설을 방지한다.
Patent KR-20010070390-A (KR)
Title: Buffering of partition tables, file system directory structures and individual file cluster chains in a mass storage device
Inventor: TRACEY D HAMMER
IPC: G06F13/10
Filed: 2001-01-03
Abstract: PURPOSE: A buffering of partition tables, a file system directory structures and an individual file cluster chains in a mass storage device are provided to accelerate access to data in a large capacity memory storage peripheral computer system. CONSTITUTION: The computer system(46) for data storage is provided with a host computer having a system RAM(50) related with the computer system and a file directory peripheral bus connected to the host computer. A large capacity memory storage peripheral computer system(56) is connected to the file directory peripheral bus, and the large capacity memory storage peripheral computer system(56) performs access to the file directory for confirming the position of the data of the large capacity memory storage peripheral computer system(56).
Patent KR-20010088315-A (KR)
Title: Negative-working resist composition for electron rays or x-rays
Inventor: ADEGAWA YUTAKA
IPC: G03F7/038
Filed: 2001-01-12
Abstract: PURPOSE: Provided is a negative-working resist composition suitably used for super-micro lithographic processes such as the productions of VLSI and high-capacity microchips, etc., and other photofabrication processes. The negative-working photoresist composition is capable of forming highly fined patterns using X-rays, electron beams, etc., and can be suitably used for fine working of semiconductor devices using a high energy such as electron beams, etc. CONSTITUTION: The negative-working resist composition for electron beams or X-rays comprises: (A) a compound generating an acid and/or radical species by the irradiation of electron beams or X-rays; (B) a resin which is insoluble in water and soluble in an alkali aqueous solution; (C) a crosslinking agent causing crosslinking with the resin of component (B) by the action of an acid, and (D) a compound having at least one unsaturated bond capable of being polymerized by an acid and/or a radical, wherein the resin of component (B) has a repeating unit shown by the following formula(a).
Patent KR-20010082090-A (KR)
Title: Method and apparatus for compressing atmospheric air, and corresponding air distillation and gas turbine installations
Inventor: COLSON ALAIN
IPC: F02C7/055
Filed: 2001-02-09
Abstract: PURPOSE: A method and equipment, air distillation facility and gas turbine facility is provided to eliminate requirement for heating air as to a problem of ice accretion on a filter, and while achieving an effective protection against fouling. CONSTITUTION: An atmospheric air passes through a liquid drop separator(3), and then passes through first and second filtration stages(5,6), in the air compressor. A bag filter element having a filtration medium including synthetic fiber increasing a density along a direction of an air flow passing the medium is used in the first filtration stage. Air of a temperature within the range of about -20deg.C to +5deg.C with respect to an outside air-temperature in a period of ice-depositing fog, supercooled rain or snow is introduced into the bag filter element.