baber/WOPTO huggingface dataset:
Patent KR-20070045419-A (KR)
Inventor: HONG SEOK HOON
IPC: G11B20/04
Filed: 2005-10-27
Abstract: 본 발명은, 엠피쓰리 파일 재생 제어방법에 관한 것으로, 예를 들어 엠피쓰리 플레이어(MP3-Player) 등에서, 사용자가 임의의 한 엠피쓰리 파일을 재생 요청하는 경우, 그 엠피쓰리 파일의 태그(Tag) 정보 내에 부가 기록된 패런털 락(Parental Lock) 정보를 검색함과 아울러, 상기 검색된 패런털 락 정보를, 기기 내에 기 설정된 패런털 락 정보와 비교하여, 상기 재생 요청된 엠피쓰리 파일을 정상적으로 재생하거나, 또는 재생 불가를 안내하는 메시지를 출력함으로써, 성인용 컨텐츠의 엠피쓰리 오디오를, 어린이 또는 청소년들이 무단으로 청취하지 못하도록, 미연에 예방할 수 있게 되는 매우 유용한 발명인 것이다.  
       
     엠피쓰리 파일, 패런털 락 정보, 태그 정보, 플래그 비트, 재생 불가
Patent KR-20070045567-A (KR)
Inventor: JIN MIN JUNG
IPC: G08G3/00
Filed: 2005-10-27
Abstract: 이더넷 통신을 통해 네트워크로 구성된 통합항해시스템이 개시된다. 이더넷 통신을 수행하기 위한 이더넷 통신선로를 구성하고, 이 네트워크는 마스터 및 슬레이브들로 연결된다. 항해 센서로부터 취득된 항해 데이터는 마스터로 입력되고, 마스터에 구비된 COM(Component Object Model) 서버를 통해 내부에 구비된 시스템으로 전송되며, 이더넷 통신선로를 통해 슬레이브들에 전송된다. 슬레이브 기능을 수행하는 다수의 워크스테이션들은 동일한 항해 데이터를 동시에 수신하여 디스플레이하며, 각각 독립적으로 응용 프로그램을 활성화하여 해당하는 정보를 확인할 수 있다.
Patent KR-20070048955-A (KR)
Inventor: LIM CHANG MOON
IPC: H01L21/027
Filed: 2005-11-07
Abstract: 본 발명은 반도체소자 제조시 이용되는 리소그래피 공정의 시뮬레이션 방법에 관한 것으로, 노광공정시 공간 이미지 ( Aerial Image ) 에 비례하여 발생하는 레지스트 내의 산 ( Acid ) 분포를 가정한 상태에서 PEB ( Post Expose Bake ) 공정에 의해 발생된 산이 확산되는 경우, 상기 레지스트 내의 블로킹 그룹 ( blocking group ) 을 연쇄적으로 디블로킹 ( deblocking ) 시키는 과정에서 디블로킹된 폴리머 농도를 수식적으로 근사하고 이를 이용하여 시뮬레이션 함으로써 실제 실험 패턴과 동일한 리소그래피 패턴을 예측할 수 있도록 하여 실험 횟수를 감소시키고, 그에 따른 반도체소자의 개발기간 단축 및 실험 비용 절감을 가능하게 하는 기술이다.
Patent KR-20070052140-A (KR)
Inventor: KIM DONG MUK
IPC: D06F75/30
Filed: 2005-11-16
Abstract: 본 발명은 다리미에 있어서, 특히 가위형 다리미를 제공하되 스팀발생장치를 더 부가토록 하여 손쉽게 옷의 주름을 펴고 또한 라인을 강하게 형성할 수 있도록 한 것을 특징으로 하는 스팀발생 기능을 갖는 가위형 다리미에 관한 것으로, 
     전체 모양이 가위 형태이며, 하단에 가열판을 장착한 고정부와,  상부에 가열판 및 스팀 발생부를 장착한 가동부와,  상기 고정부 및 가동부를 연결하는 연결라인과,  상기 연결라인을 결합하는 힌지와,  상기 연결라인에 연장되며 고정부와 가동부를 밀착시켜 다림질을 유도하는 고정부 손잡이 및 가동부 손잡이를 포함하여 구성함이 특징이며; 
     본 발명은 180도로 회전하는 가동부를 제공하여 필요에 따라서 옷을 매단체 다림질할 수 있고, 바닥에 옷을 놓고 다릴 수도 있으며, 옷을 다리면서 스팀을 분사토록 하여 다림질 효과를 극대화시킬 수 있다. 
       
     스팀, 가위, 다리미
Patent KR-20070052985-A (KR)
Inventor: YANG WON HOI
IPC: E02B3/06
Filed: 2005-11-18
Abstract: 본 발명은 소파블럭 직립 적치식 방파제 및 설치방법에 관한 것으로, 더욱 상세하게는 외해측 골조체와 내해측 골조체를 형성하고, 상기 외해측 골조체와 내해측 골조체 사이에 소파블럭을 직립 적치하며, 상기 외해측 골조체의 상부와 상기 내해측 골조체의 상부를 체인으로 서로 연결하여 상기 소파블럭과 이 소파블럭의 전후에 위치된 골조체가 서로 일체화 되도록 함으로써 파랑을 저지하는 방파제의 기능을 하게 됨과 아울러, 제체의 안정성과 소파기능이 향상되어 기상이변에 대한 확실한 예방효과를 얻을 수 있는 방파제 및 이 방파제의 설치방법을 제공한다.
Patent KR-20070056448-A (KR)
Title: Composition for preventing bone loss comprising salvia miltiorrhiza extracts and chitosan
Inventor: KIM HYUNG RYONG
IPC: A61P19/10
Filed: 2005-11-29
Abstract: A composition comprising a plant extract is provided to be effectively used for treating or preventing osteoporosis, inhibit lowering of bone density and promote the calcium absorption into the bone. The composition for preventing bone loss comprises an extract of Salvia miltiorrhiza as an effective ingredient. The composition further comprises chitosan. In the composition, the weight ratio of the extract of Salvia miltiorrhiza and the chitosan is 1:1-5:1.
Patent KR-20070058232-A (KR)
Title: Composition for preparing thermosetting resin, thermosetting resin prepared by the same, and thermosetting resin composition comprising the same
Inventor: KIM SUNG HYUN
IPC: C08F20/06
Filed: 2005-12-01
Abstract: Provided is a composition for forming a thermosetting resin, which uses a trimethoxysilane group-containing mercaptan compound as a chain transfer agent to provide excellent smoothness, adhesion to a substrate and film strength, and is useful for preparing a protective film for a color filter. The composition for forming a thermosetting resin comprises: (1) (a) monomers comprising 10-30 mole% of an acid group-containing monomer based on the total monomers, (b) 30-50 mole% of an epoxy group-containing monomer based on the total monomers, and (c) 20-60 mole% of an unsaturated ethylene group-containing monomer based on the total monomers; and (2) 0.2-10 parts by weight of a chain transfer agent represented by a formula 1, based on 100 parts by weight of the monomers. In the formula 1, n is an integer of 3-12.
Patent KR-20070059663-A (KR)
Title: Multi-function switch system of vehicle
Inventor: LEE JOON HO
IPC: H01H25/04
Filed: 2005-12-07
Abstract: A multi-function switch system of a vehicle is provided to obtain a space in an armrest by using a joystick without using a two-step contact switch. A multi-function switch system of a vehicle includes a main body(10), a mode switch(12), a hold switch(13), a display unit(11), a joystick(14), and a four-directional switch(15). The main body(10) is installed on an armrest. The mode switch(12) selects a control object. The hold switch(13) is a locking device. The display(11) displays information according to selection of a driver. The joystick(14) allows the driver to control a plurality of contacts. The four-directional switch(15) precisely controls the object controlled by the joystick(14).
Patent KR-20070060938-A (KR)
Title: Method for efficient plsc information decoding of dvb-s2 transmission frame
Inventor: KIM PAN SOO
IPC: H04N7/24
Filed: 2005-12-09
Abstract: A decoding method for detecting a PLSC(Physical Layer Signaling Code) of a satellite broadcasting system frame is provided to improve reliability of PLSC decoding by performing (32,6) Reed-Muller decoding in parallel and reduce the quantity of calculations. A symbol vector is received, and a sum vector and a difference vector of a symbol pair are obtained from the received symbol vector. (32,6) Reed-Muller decoding using Hadamard matrix is performed on the sum vector and the difference vector to estimate a message bit of the sum vector and a message bit of the difference vector. The message bits are PLSC-encoded and modulated(403,404). A difference between the received symbol vector and a symbol according to the sum vector and a difference between the received symbol vector and a symbol according to the difference vector are calculated and compared to each other(405,406). When the difference according to the sum vector is smaller than the difference according to the difference vector, it is determined that Reed-Muller codeword is repeated. When the difference according to the sum vector is greater than the difference according to the difference vector, it is determined that Reed-Muller codeword is inverted.
Patent KR-20070036558-A (KR)
Inventor: LEE IHL HO
IPC: G11C8/10
Filed: 2005-12-16
Abstract: 본 발명은 컬럼 디코더에 관한 것으로서, 특히, 오프 누설 전류가 가장 많이 발생되는 뱅크의 컬럼 디코더에서 벌크 바이어스 전압을 제어하여 반도체 메모리 소자의 전체적인 오프 누설 전류를 줄일 수 있도록 하는 기술을 개시한다.  이러한 본 발명은 컬럼 어드레스 정보를 포함하는 코드신호를 입력받아, 컬럼 액세스 동작시 코드신호가 일치할 경우 로우 신호를 출력하고, 코드신호가 일치하지 않을 경우 하이 신호를 출력하는 프리 구동부, 및 프리 구동부의 출력이 로우 신호일 경우 컬럼 선택신호를 활성화시키고, 프리 구동부의 출력이 하이 신호일 경우 컬럼 선택신호를 비활성화시키는 구동부를 포함하고, 프리 구동부와 구동부에 포함된 PMOS트랜지스터의 벌크 바이어스 전압으로 펌핑전압 레벨이 인가되고, 프리 구동부와 구동부에 포함된 NMOS트랜지스터의 벌크 바이어스 전압으로 백바이어스 전압 레벨이 인가된다.   
       
     오프, 누설, 전류, 트랜지스터, 벌크, 컬럼, 디코더
Patent KR-20070066045-A (KR)
Title: Method and apparatus for generating gamma voltage and liquid crystal display using the same
Inventor: AHN HYEONG CHEOL
IPC: G09G3/36
Filed: 2005-12-21
Abstract: A method and an apparatus for generating a gamma voltage and an LCD device using the same are provided to expand a gamma voltage range by using a negative low common voltage, thereby enhancing display quality. An LCD(Liquid Crystal Display) device includes a liquid crystal panel(30), a power supply unit(20), a gamma voltage generating unit(22), and a data driver(26). The power supply unit generates an alternative common voltage, which is alternated between high and low common voltages, supplies the generated alternative common voltage to the liquid crystal panel, and generates and supplies a gamma driving voltage. The gamma voltage generating unit divides a voltage, which is between the gamma driving voltage and the low common voltage, into plural gamma voltages, and supplies the gamma voltages. The data driver selects a gamma voltage corresponding to data from the plural gamma voltages, and supplies the selected gamma voltage to the liquid crystal panel.
Patent KR-20070071925-A (KR)
Title: Microphone apparatus having a horizontal sensing device
Inventor: KU HEE DOO
IPC: H04B1/40
Filed: 2005-12-30
Abstract: A mobile terminal having a level detection unit is provided to enable a user to watch on TV or a moving picture through a wide screen by changing the size of a screen displayed on an LCD of a display part according to a level state detection signal outputted from a level detection unit. A mobile terminal comprises a level detection unit(40) and a screen change signal generation part(39). The level detection unit(40) generates a detection signal to detect a level state. The screen change signal generation part generates a screen change signal to change the size of a screen displayed on an LCD window of a display part(33) according to a detection signal outputted from the level detection unit under the control of a control part(37). The level detection unit(40), supplied power from a battery(38), detects the inclination of the mobile terminal and outputs a detection signal. The control part(37), based on a detection signal generated from the level detection unit(40), outputs a control signal so that a screen, of which the width is wider than the depth or of which the depth is wider than the width, can be outputted through the display part.
Patent KR-20070072100-A (KR)
Title: Grinder for grinding machine
Inventor: YU SEOG HYUN
IPC: B24D5/00
Filed: 2005-12-30
Abstract: A grinder for a grinding machine is provided to prevent deformation of a grinding stone holder during grinding of the inner surface of a workpiece. A grinder for a grinding machine includes a grinding stone holder(10) and a grinding stone(20). The grinding stone holder is rotatably coupled to a spindle of grinding equipment. The grinding stone is directly fitted and bonded to the grinding stone holder such that the grinding stone rotates together with the grinding stone holder and grinds the inner surface of a workpiece. The grinding stone holder includes a grinding stone fixing part(11) having a front end to which the grinding stone is bonded; and a holder coupling part(12) formed at a rear end of the grinding stone fixing part so as to be screw-coupled to the spindle of the grinding equipment.
Patent KR-20050042781-A (KR)
Title: Resin composition for vibration-damping material, vibration-damping material, and sound-insulating member
Inventor: ABE HIROYUKI
IPC: C08L27/06
Filed: 2001-04-12
Abstract: A sound-insulating member combining high vibration-damping performance with high sound-insulating performance; a vibration-damping material constituting the member; and a resin composition for obtaining the material. A first embodiment of the resin composition for a vibration- damping material comprises 100 parts by weight of a chlorinated thermoplastic resin and 20 to 200 parts by weight of a chlorinated paraffin having 12 to 16 carbon atoms on the average. The chlorinated thermoplastic resin has a chlorine content of desirably 20 to 70 wt.%, preferably 30 to 70 wt.%. The chlorinated paraffin has a combined chlorine content of desirably 30 to 70 wt.%, preferably 35 to 65 wt.%.
Patent KR-20050039875-A (KR)
Title: Navigation system with acoustic route information
Inventor: BRUELLE-DREWS CHRISTIAN
IPC: G08G1/0962
Filed: 2003-02-24
Abstract: A navigation system (100) capable of providing acoustic route information summarizing a route to a predetermined destination. The navigation system (100) includes a route calculation module (110) that is capable of calculating a route to a trip destination. A route overview module (104) may also be included for creating a route overview list that is based on the route. An acoustic message module (108) may be used to generate at least one acoustic route overview message as a function of the route overview list associated with the route.
Patent KR-20050083855-A (KR)
Title: Compositions and methods for sirna inhibition of hif-1 alpha
Inventor: REICH SAMUEL JOTHAM
IPC: A61K38/00
Filed: 2003-10-31
Abstract: RNA interference using small interfering RNAs which target HIF-1 alpha mRNA inhibit expression of the HIF-1 alpha gene. As HIF-1 alpha is a transcriptional regulator of VEGF, expression of VEGF is also inhibited. Control of VEGF production through siRNA-mediated down-regulation of HIF- 1 alpha can be used to inhibit angiogenesis, in particularly in diseases such as diabetic retinopathy, age related macular degeneration and many types of cancer.
Patent KR-20050086637-A (KR)
Title: A method of using long cellized codes in a joint detection system
Inventor: LI FENG
IPC: H04W76/02
Filed: 2003-11-13
Abstract: The present invention relates to a method of using long cellized codes in a joint detection system, in which transmitting signal using a long cellized code, which is longer than the maximum length 16 of the system despreading code and is multiple of 16, and receiving side still uses a received signal processing method of multiuser detection technology. The method includes : estimating a user channel for each antenna element to obtain the result of user channel estimation for each antenna element; generating a first intermediate matrix associating with the long cellized code selected and the result of user channel estimation for each antenna element; generating a second intermediate matrix and a conjugated and transposed matrix thereof according to the first intermediate matrix, and generating a third intermediate matrix according to the second intermediate matrix and the conjugated and transport matrix thereof; Cholesky decomposing the third intermediate matrix, the decomposition factor associated with the length of the long cellized code selected; performing the demodulating operation according to the Cholesky decomposing result of the third intermediate matrix and the received signal of all antenna elements after match-filtered. The computational complexity of the whole operation is acceptable.
Patent KR-20050088085-A (KR)
Title: System and method for establishing trust without revealing identity
Inventor: BRICKELL ERNIE
IPC: H04L9/32
Filed: 2003-11-06
Abstract: One aspect of an embodiment of the invention provides a method, system, and device to prove to a challenger that a prover device has a signature from a device manufacturer without revealing the signature to the challenger. According to one implementation, a challenger is provided with the result of a one-way function of a secret held by a prover device. An interactive proof is employed, between the prover device and the challenger, to prove to the challenger that the secret used in the one- way function has been signed by a device signature without revealing the secret or the device signature or the prover device's identity to the challenger.
Patent KR-20050085332-A (KR)
Title: Disposable undergarment with a detachable crotch member and method for the use thereof
Inventor: VAN GOMPEL PAUL T
IPC: A61F13/15
Filed: 2003-09-11
Abstract: A disposable undergarment includes a body chassis member elongatable in at least a first direction between at least a first condition and second condition. The body chassis member has a greater elongation when in the second condition than when in the first condition. The disposable undergarment further includes a crotch member detachably connected to the body chassis member at at least one attachment location. At least a portion of the at least one attachment location is detached as the body chassis member is elongated between the first and second conditions. In one preferred embodiment, the crotch member includes an absorbent component. Methods of using the undergarment and of instructing a user about the use of the garment are also provided.
Patent KR-20050085366-A (KR)
Title: Disposable absorbent articles having multiple absorbent core components including replaceable components
Inventor: LAVON GARY DEAN
IPC: A61F13/42
Filed: 2003-11-26
Abstract: A disposable absorbent article adapted to be worn about a lower torso of a human body and having a chassis, a non-removable absorbent core component disposed in a crotch region of the chassis, and a replaceable absorbent core component disposed in capillary liquid communication with the non-removable absorbent core component. The replaceable absorbent core component may be removed and a like component may be substituted in place of the removed component without the removal of the absorbent article from the wearer. The replaceable absorbent core component may be disposed inside an openable chassis pocket, with access for its removal and replacement provided by an aperture in a backsheet, an openable end of an external pocket, or an openable end of an internal pocket formed at an area of a waist end edge where the backsheet and a topsheet may be separated. Additional replaceable absorbent core components may also be incorporated.
Patent KR-20050085376-A (KR)
Title: Gamma correction
Inventor: DE HAAN GERARD
IPC: H04N5/202
Filed: 2003-11-06
Abstract: An image-processing unit (300) for transforming pixel values of a first video signal (Video1) into respective pixel values of a second video signal (Video2), on basis of the luminance-to-light transfer characteristic of a display device is disclosed. The image-processing unit (300) comprises: a band-split filter (302) for band-splitting the first video signal (Video1) into a first high-frequent signal (HF1) and a first low-frequent signal (LF1); a first pixel value transformation unit (304) for transforming the first high- frequent signal (HF1) into a second high-frequent signal (HF2) on basis of a first transfer function; a second pixel value transformation unit for transforming the first low-frequent signal (LF1) into a second low- frequent signal (LF2) on basis of a second transfer function which is different from the first transfer function; and a combining unit (308) for combining the second high-frequent signal (HF2) and the second low- frequent signal (LF2) into the second video signal (Video2).
Patent KR-20050085606-A (KR)
Title: Memory device and method having low-power, high write latency mode and high-power, low write latency mode and/or independently selectable write latency
Inventor: JOHNSON CHRISTOPHER S
IPC: G11C7/10
Filed: 2003-12-09
Abstract: A logic circuit operates write receivers in a dynamic random access memory device in either a low-power mode, high write latency mode or a high-power mode, low write latency mode. The logic circuit receives a first signal indicative of whether the high- power, low write latency mode has been enabled, a second signal indicative of whether a row of memory cells in the memory device is active, a third signal indicative of whether the memory device is being operated in a power down mode, and a fourth signal indicative of whether read transmitters in the memory device are active. The logic circuit maintains power to the write receivers whenever the high-power, low write latency mode has been enabled if a row of memory cells in the memory device is active, the memory device is not being operated in the power down mode, and the read transmitters in the memory device are not active.
Patent KR-20050105982-A (KR)
Title: Benzofuran derivative
Inventor: SATO SEIICHI
IPC: A61P19/02
Filed: 2004-03-03
Abstract: (wherein R1 represents optionally substituted alkyl or optionally substituted alkenyl; and R2 and R3 each represents hydrogen, alkyl, hydroxyalkyl, dihydroxyalkyl, or alkynyl, provided that R2 and R3 may form an optionally substituted, nitrogenous, saturated, heterocyclic group in cooperation with the adjacent nitrogen) and a medicinal composition containing the compound. The compound functions to inhibit the production of a tumor necrosis factor (TNF-alpha) and has satisfactory oral absorbability.
Patent KR-20060003331-A (KR)
Title: Anti-microbially active diamine-based guanine derivatives
Inventor: GEORGOPOULOS APOSTOLOS
IPC: A61K31/155
Filed: 2004-03-17
Abstract: The invention relates to the use of a polymer guanine derivative based on a diamine comprising oxyalkylene chains between two amino groups, whereby the guanine derivative is a product of polycondensation of a guanidine acid addition salt with a diamine comprising polyakylene chains between two amino groups, used in the production of an antimicrobially active medicament.
Patent KR-20060013649-A (KR)
Title: Method for determining the energy of a knock signal for an internal combustion engine
Inventor: GALTIER FREDERIC
IPC: F02P5/152
Filed: 2004-04-30
Abstract: The invention relates to a method for determining the energy (KNKE) of the knock of an internal combustion engine, using an analog signal supplied by a sensor fixed to said engine. The inventive method comprises the following steps: a) the analog signal is shaped, b) said analog signal is converted into a sequence of digital samples, c) the signal is subjected to digital filtering, and d) the signal is adjusted and e) integrated. According to said method: i) the shaping of the analog signal includes combining the signal with a continuous component (Vcnf) adapted to render said shaped signal a positive signal or a zero signal, and ii) the digital filtering is carried out by means of a band-pass filter with an infinite impulse response, the transfer function thereof comprising a zero for the zero frequencies.
Patent KR-20060018239-A (KR)
Title: System, method and apparatus for facilitating media content channels
Inventor: NYKANEN PETRI
IPC: H04H20/00
Filed: 2004-05-17
Abstract: A system, method and apparatus that enables end user (402) of mobile terminal (430) to establish primary content channel (426) having primary content feedback provided via path (434). In response, User Interface (UI) logic block (404) detects the primary content channel selection and queries media channel controller (406) for secondary content channel selections that may be instantiated in response to the primary content channel selection. Secondary media channel (428) is automatically established upon an affirmative match made between parameters contained within database (408) and characteristics associated with the primary media channel selection.
Patent KR-20070073357-A (KR)
Title: Plasma display apparatus
Inventor: RYU SEONG HWAN
IPC: G09G3/20
Filed: 2006-01-04
Abstract: A plasma display device is provided to reduce a noise while a data pulse is applied, by adjusting application timing of the data pulse to a data electrode during an address period. A plasma display device includes a PDP(Plasma Display Panel,400), a scan driver(420), a sustain driver(430), and a data driver(410). Scan and sustain electrodes are formed on the PDP. The scan driver applies a falling pulse before a first scan pulse is supplied to the scan electrode during an address period, and then applies a first rising pulse to the scan electrode. The sustain driver applies a predetermined driving pulse to the sustain electrode corresponding to the scan driver. The data driver applies the data pulse to one of plural data electrode groups composed of at least one data electrode at different timing from other data electrode groups during an address period of at least one sub-field in a frame.
Patent KR-20060082414-A (KR)
Inventor: HIROTA HISATOSHI
IPC: F04B27/14
Filed: 2006-01-11
Abstract: 본 발명의 과제는 압력 제어 구간에 있어서 안정적으로 동작할 수 있는 동시에, 솔레노이드의 비통전시에는 가변 용량 압축기를 토출 용량 최소의 운전으로 신속하게 이행시킬 수 있는 가변 용량 압축기용 제어 밸브를 제공하는 것이다.   
     가변 용량 압축기용 제어 밸브에 있어서는, 압력 제어 구간에 있어서 밸브체에 부여되는 밸브 폐쇄 방향의 힘이 증가하여, 냉매 압력에 의해 밸브체에 부여되는 밸브 개방 방향의 힘과 평형화되기 때문에 안정된 압력 제어를 실현할 수 있다.  또한, 밸브체가 압력 제어 구간의 종점 위치를 넘으면, 밸브체에 부여되는 밸브 폐쇄 방향의 힘이 감소함으로써 전체 개방시의 밸브 개방도가 커지기 때문에, 솔레노이드의 비통전시에 있어서 충분한 냉매 유량을 확보할 수 있어, 가변 용량 압축기를 토출 용량 최소의 운전으로 신속하게 이행시킬 수 있다.   
       
     가변 용량 압축기용 제어 밸브, 밸브 구성부, 솔레노이드, 본체, 밸브 구멍