baber/WOPTO huggingface dataset:
Patent KR-20010072105-A (KR)
IPC: F02M69/00
Filed: 1999-08-02
Abstract: A duct system suitable for use as an intake manifold for an internal combustion engine, including flap valves (13) for selective opening and closing of the ducts. The positions of the valves are continuously adjustable in order to produce a swirl in the flow of combustion air. To achieve this, a high degree of angular precision is required in the positioning of the valves. Intake manifold manufacturing tolerances need to be compensated during assembly of the valves. A valve adjusting mechanism is provided in mechanical couplings (23) of the valve linkage between the position adjusting motor (19) and the flap valves (13).
Patent KR-20010086375-A (KR)
IPC: H04B7/26
Filed: 2000-06-29
Abstract: 통신 단말은, 통신중인 기지국 전체로부터 송신 전력 감소의 제어를 받은 경우에만 송신 전력을 감소시키고, 그 이외의 경우에는 송신 전력 감소의 제어를 행하지 않는다.  또한, 통신 단말은 통신중인 기지국으로부터의 과거의 송신 전력 제어 정보를 축적하여, 전력 증가 제어가 연속하고 있는 경우에는 다른쪽 기지국으로부터의 송신 전력 제어 정보에 따르고, 연속하지 않고 있는 경우에는, 통신중인 모든 기지국으로부터 송신 전력 감소의 제어를 받으면 송신 전력을 감소시키고, 송신 전력 감소의 정보가 전부가 아닐 때에는 송신 전력 감소의 제어를 하지 않는다.
Patent KR-20010086397-A (KR)
IPC: H03K3/037
Filed: 1999-09-01
Abstract: 본 발명에 따른 디지털 회로는, 제 1 스위치 소자(S1)를 통해 입력 신호를 제공하기 위한 입력(In) 및 회로를 활성 상태 또는 비활성 상태로 변위시킬 수 있는 활성 입력(EN)을 포함한다.  상기 디지털 회로는 또한, 회로의 활성 상태에서 제 1 스위치 소자(S1)의 차단 직전에 입력 신호의 레벨을 반전되지 않은 상태로 제공하는 제 1 출력(A), 및 회로의 활성 상태에서 제 1 스위치 소자(S1)의 차단 직전에 입력 신호의 레벨을 반전된 상태로 제공하는 제 2 출력(/A)을 포함한다.  회로가 비활성 상태인 경우에는, 상기 2개 출력(A, /A)에 제 1 논리 레벨(1)이 제공된다.  본 발명에 따른 회로는 또한, 입력측이 회로의 2개 출력(A, /A)에 연결되고 출력측이 제 1 스위치 소자(S1)의 제어 단자에 연결된 논리 유닛(L)을 포함한다.  회로의 2개 출력(A, /A)에 제 1 논리 레벨(1)이 인가되는 경우에는 상기 논리 유닛(L)이 제 1 스위치 소자(S1)를 전도성으로 접속시키고, 회로의 2개 출력(A, /A)에 제 2 논리 레벨(0)이 인가되는 경우에는 상기 논리 유닛(L)이 제 1 스위치 소자(S1)를 차단한다.
Patent KR-20010088847-A (KR)
IPC: G03F7/027
Filed: 1999-10-05
Abstract: 본 발명은 X-선, 전자 비임, 이온 비임 및 감마선과 같은 이온화 방사선에 노출시에 화상으로 중합/가교될 수 있는 조성물을 개시한다.  본 발명은 또한 세라믹의 미세조립, 입체 리소그래피, 및 포토레지스트를 위해 사용가능한 X-선, e-비임 및 이온 비임 리소그래피를 위해 상기 조성물을 사용하는 방법을 개시한다.
Patent KR-20010101831-A (KR)
IPC: G01N33/36
Filed: 2000-01-26
Abstract: 본 발명은 섬유가 고강도의 단색광으로 조사되는 폴리에틸렌 테레프탈레이트 섬유의 염착량 측정방법에 관한 것이다.  감광성 센서가 라만 산란을 측정하는 데 사용되며, 본 라만 산란을 조성과 구조가 공지된 폴리에틸렌 테레프탈레이트 섬유의 라만 스펙트럼을 기본으로 하는 초기 설정된 모델의 라만 스펙트럼과 비교한다.  본 모델은 염착량의 정량적 척도를 구성하는 밀도를 계산하는 데 사용된다.  계산시, 598 내지 1900㎝ -1 의 스펙트럼 측정 범위내의 다수의 영역으로부터의 측정 지점이 사용된다.
Patent KR-20010102023-A (KR)
IPC: A61B6/03
Filed: 2000-12-13
Abstract: 다중 검출기(multi-detector)를 포함하는 CT 장치에 의한 나선형 스캔(helical scan) 수행시의 이미지 잡음의 허용값에 대해 과도하거나 또는 부족하게 되지 않으면서 방사선량(radiation dose)을 결정하기 위한 목적으로, 본 발명의 방법은 다중 검출기를 포함하는 X선(X-ray) CT 장치에 의한 나선형 스캔에 의해 생성될 X선 단층 촬영 이미지(tomographic image)의 이미지 두께를 선택하고(단계 ST1), 단일 슬라이스 CT 방사선량 결정 알고리즘(single-slice CT radiation dose determining algorithm)을 이용하여 단일 슬라이스 CT에 의해 이미지 두께를 갖는 X선 단층 촬영 이미지를 획득시 X선 선량을 임시 결정하고(단계 ST2), 스캔 프로토콜을 선택하고(단계 ST3), 선택된 이미지 두께를 매칭시키는 선량 보정 계수 테이블(dose correction factor table)로부터 선량 보정 계수를 판독하고(단계 ST4), 선량 보정 계수에 의해 X선 선량을 보정하고(단계 ST5), 튜브 전류(tube current) 및 방사 시간(emission time) 중 적어도 하나를 지정함으로써 단층 촬영 이미징 스캔 조건(tomographic imaging scan condition)을 결정하고(단계 ST6), 나선형 스캔을 수행하여 X선 단층 촬영 이미지를 디스플레이(단계 ST7)하는 단계를 포함한다.   따라서, 대상물(subject)이 필요 이상으로 노출되는 문제점을 방지할 수 있다.
Patent KR-20010111304-A (KR)
Title: Recovery in mobile communication systems
IPC: H04W24/04
Filed: 2000-04-14
Abstract: The present invention relates to a method of recovering from a processor fault in a mobile communication network node provided with a plurality of processors. In use, connections are established between the network node and mobile stations for packet data communication between the network node and the mobile station. The connections are classified into priority order on basis of predefined classifying parameters. Working condition of at least one of the processors of the network node is monitored, and in case of detecting a processor fault, user plane connections are relocated within the network node from the faulted processor to another processor in accordance with the classified priority order of the connections. The invention relates further to a network node.
Patent KR-20010112450-A (KR)
IPC: G11B11/00
Filed: 2001-02-09
Abstract: 재기록가능한 데이터 저장매체(1)는 트랙킹 구조(8)를 구비한 재기록가능한 기록층(9)을 갖는다. 상기한 기록층(9)은 데이터 기록 영역(5)을 갖는다. 데이터 기록 영역(5) 이외의 식별 마크 영역(4, 4')에 소거가능한 식별 마크가 존재한다. 데이터 기록 영역(5)은 제 1 트랙킹 구조(8')를 갖는 한편, 식별 마크 영역(4, 4')은 트랙킹 구조를 거의 갖지 않거나, 제 1 트랙킹 구조(8')와 다른 제 2 트랙킹 구조(8")를 갖는다. 따라서, 레코더의 소거 스폿의 위치가 반경방향으로 정밀하게 제어될 수 없기 때문에, 식별 마크의 소거가 실질적으로 불가능하다.
Patent KR-20020022652-A (KR)
Title: Apparatus for transporting carriers to a processing station and method of operating the same
IPC: G02B21/00
Filed: 2000-07-03
Abstract: The present application a transporter (100) for transporting specimen carriers (8) to a processing station (40), comprising a first vertical input magazine (1) of carriers (8), a second vertical output magazine (6) of carriers, and a singulator (3) located between the first and second magazines (1, 6). The first and second magazines (1, 6) may be located one above the other. Preferably, the first and second magazines (1, 6) and the singulator (3) are vertically aligned so that a carrier (8) follows a straight vertical path. This provides a compact arrangement which takes up the minimum of floor space in the laboratory. The singulator (3) receives carriers (8) one-at-a-time from the input magazine (1) and moves them vertically to a processing position (40). After processing, the singulator (3) then delivers each carrier to an output location where it is transferred to the output magazine (6). The singulator (3) may move a carrier (8) upwards or downwards at the processing position (40) independent of any movement of the carriers (8) in the input and/or output magazines (1, 6). The drives for the input and output magazine (1, 6) are preferably simply gravity drives but the present invention is not limited thereto. The drive (10) for the singulator is preferably a stepping motor or DC servo-motor.
Patent KR-20020011391-A (KR)
Title: 개선된 광증백제 캐리어를 갖는 종이 코팅 조성물
IPC: D21H19/54
Filed: 2000-04-27
Abstract: 광증백제(OBA) 및 5 중량%의 중합체 농도로 분산시 1,500 cps 미만의 수 중 수성 브룩필드 점도를 나타내는 저점도의 비이온계 수용성 다당류 유도체를 포함하는 종이 코팅 조성물로서, 상기 종이 코팅물은 상기 비이온계 수용성 다당류 유도체를 포함하지 않는 동일한 제제에 비해 개선된 광택성을 제공한다.  이 조성물로 코팅된 종이는 70 보다 큰 광백색도 값을 나타낸다.
Patent KR-20020012226-A (KR)
Title: A sorting conveyer with a tilting mechanism
IPC: B65G47/96
Filed: 2000-05-22
Abstract: A tilting mechanism comprising an article-supporting member, such as a tray or a conveyor belt for a sorter for transporting and sorting various articles is disclosed. The article-supporting member may be held tilted about two parallel axes each being fixed with respect to the tilting part or the stationary part and being movable along a predetermined path with respect to the other part. Further is disclosed a sorter comprising article-supporting members arranged on tilting mechanisms to tilt the members when passing curves and during induction of articles from the side of the sorter so as to prevent articles from sliding off the members and thus enable the sorter to operate at much higher conveying speeds than known sorters.
Patent KR-20020016829-A (KR)
IPC: G02F1/13
Filed: 2000-06-09
Abstract: 본 발명은 전지-광학 변환성 구성부와 함께 발색제 성분을 보유하는 전기 광학 셀을 구성하되, 전원이 있거나 없는 가변성 투과율의 전기 광학 장치(29)를 제공한다.  발색제 성분은 광 발색, 열 발색 및/또는 이색성 물질 및 이들의 혼합물일 수 있다.  발색제 성분은 전기-광학 셀내 투명 기판(37 및 39)중 하나 이상의 면의 코팅, 필름 또는 층일 수 있거나 셀의 전기-스위칭전환성 물질(43)의 일부분일 수 있다.  전기-광학 장치는 하나는 액정 물질내에 존재하는 하나 이상의 이색성 염료를 보유하는 액정 셀일 수 있다.  본 발명의 다른 양태에서, 발색성 성분은 전기-광학 장치가 보유하거나 상기 장치 내부에 존재하는 발색제 게스트 물질일 수 있다.  발색제 물질을 보유하는 전기 광학 장치는 프라이버시 글래스(privacy glass), 차양용 밴드 및 승객 칸막이용 스크린과 같은 자동차용 투명체; 천창 및 그밖의 창과 같은 건축용 창; 및 안경류와 같은 용도에 적당하다.
Patent KR-20030061064-A (KR)
Inventor: LEE GYU CHAE
IPC: D06F39/08
Filed: 2002-01-10
Abstract: PURPOSE: A washing machine is provided to improve washing efficiency by guiding sufficient water upward by contacting a rising water current guide to a dewatering tub, to efficiently filter foreign materials, and to prevent the laundry from being damaged. CONSTITUTION: A washing machine is composed of a housing forming an external appearance, a water tub installed inside the housing to house water, a dewatering tub(30) disposed inside the water tub to rotate, and a pulsator installed inside the dewatering tub to generate washing water current. The dewatering tub has a floor plate(40) and a body(50) extended upward at a constant length from the periphery of the floor plate. In additional, the washing machine includes a rising water current guide(60) installed to the body of the dewatering tub to guide water current generated by the pulsator to the upside of the dewatering tub and a water inflow hole(41a) and a water outflow hole integrally formed at the floor plate to flow washing water current in the rising water current guide.
Patent KR-20030063540-A (KR)
Title: Manufacturing method for infrared detector
Inventor: LEE HUI CHEOL
IPC: H01L21/00
Filed: 2002-01-22
Abstract: PURPOSE: A method for fabricating an infrared detector is provided to prevent an interface of a p-n junction of HgCdTe from being damaged and prevent a leakage current by selectively making hydrogen ions or atoms diffused to a predetermined depth of a low density p-type HgCdTe layer while using hydrogen plasma. CONSTITUTION: The low density p-type HgCdTe layer(2) is formed on a transparent substrate(1). A diffusion barrier layer is formed to expose a predetermined part of the upper portion of the low density p-type HgCdTe layer. Hydrogen ions and hydrogen atoms are diffused to the exposed low density p-type HgCdTe layer to form a low density n-type HgCdTe layer(4) by using hydrogen plasma so that the p-n junction is formed. The diffusion barrier layer is removed. An insulation layer is formed on the low density p-type HgCdTe layer and the low density n-type HgCdTe layer. A contact hole is formed in the insulation layer to expose a predetermined portion of the low density p-type HgCdTe layer and the low density n-type HgCdTe layer. A plug is formed which contacts the upper portion of the low density p-type HgCdTe layer and the low density n-type HgCdTe layer in the contact hole. A metal layer is deposited on the resultant structure and is patterned to form a pad that contacts the plug and has a predetermined area on a part of the upper portion of the insulation layer.
Patent KR-20030063900-A (KR)
Title: device for removing the odor in refrigerator
Inventor: SHIN SU YEON
IPC: F25D23/00
Filed: 2002-01-24
Abstract: PURPOSE: A deodorizing apparatus for a refrigerator is provided to resolve and eliminate various ill-smelling elements or microorganisms included in cool air circulating through the refrigerator, by using harmless plasma photocatalyst reaction. CONSTITUTION: A deodorizing apparatus for a refrigerator includes a plasma reactor comprising a discharge electrode(110) and a ground electrode(120) coated with oxidized titanium, and a high-voltage-generating unit(130) electrically connected to the discharge electrode. The plasma reactor is disposed to a cooling air duct(7) circulating through the refrigerator. The high-voltage-generating unit applies voltage with superposed pulse to the discharge electrode and activates the generation of a negative ion. Thus, deodorizing performance of the deodorizing apparatus is improved.
Patent KR-20030065049-A (KR)
Title: Method for controlling exit and entrance according to facial recognition and apparatus thereof
Inventor: HWANG JIN SANG
IPC: G06K9/00
Filed: 2002-01-29
Abstract: PURPOSE: A method and a device for controlling entrance/exit by face recognition are provided to control entrance/exit by discriminating regular face image and non-regular face image of authorized person. CONSTITUTION: A touch screen display part(120) makes the user input the entrance/exit request and displays a required item corresponding to the request by installing outside of the gate(170). A camera(110) pictures a face image of the user if the user requests the entrance/exit. A face recognizer(130) inputs the face image to the camera(110), converts an inputted face signal into the data specifying the biometric recognition of the user, sets up the data as the standard face data, and outputs a result signal by comparing a normal face image with an abnormal face image of the user. A memory(140) stores the normal and the abnormal face image of the registered user. A controller(150) outputs a lock or an unlock signal to a lock driving part(160) according to the result signal.
Patent KR-20030029007-A (KR)
Title: Sound Field Controllable Audio System
Inventor: KIM SOON JA
IPC: G10K11/00
Filed: 2002-02-05
Abstract: PURPOSE: An audio system is provided to effectively control a sound field in a concert hall by using a high-powered ultrasonic wave generating device without remodeling sidewalls and a ceiling of the concert hole. CONSTITUTION: A reflection wall formed at a ceiling of a concert hole is replaced with a first high-powered ultrasonic wave generating device(1051) capable of reflecting a sound wave. A part of a rear wall of the concert hole is replaced with the first high-powered ultrasonic wave generating device(1051) capable of reflecting the sound wave and the remaining of the rear wall of the concert hall is replaced with a second high-powered ultrasonic wave generating device(1031) capable of absorbing the sound wave. Thus, reflection degree and absorbing degree of the sound wave are electrically controlled. The first high-powered ultrasonic wave generating device(1051) is also installed at the front of a stage in order to prevent a howling phenomenon.
Patent KR-20030069250-A (KR)
Title: Frame for plasma display panel
Inventor: EUN JONG MYEONG
IPC: H01J17/16
Filed: 2002-02-19
Abstract: PURPOSE: A frame of a plasma display panel is provided to allow the frame to be fixed to the set case regardless of the size of the set case. CONSTITUTION: A frame comprises a frame(30) for supporting a panel and radiating heat from the panel; a first fixing unit(33) formed integrally with the frame and mounted at the edge of the frame; and a second fixing unit(32) mounted on the first fixing unit and the frame in such a manner that the second fixing unit is attachable/detachable to/from the first fixing unit and the frame. The set case covering the frame and the panel is fixed at the first fixing unit when the set case has a size lower than the first preset size. The second fixing unit is mounted on the first fixing unit and the set case is fixed at the second fixing unit when the set case has a size larger than the first preset size.
Patent KR-20030070159-A (KR)
Title: A water supply distributing equipment for the absorption of water hammer and it's piping system
Inventor: KIM JIN SU
IPC: F16L55/045
Filed: 2002-02-21
Abstract: PURPOSE: A distribution equipment for preventing water hammer and a piping system for water supply using the same is provided to quickly check the water leakage and effectively prevent the water hammer. CONSTITUTION: A distribution equipment for preventing water hammer comprises a distribution head part distributing the fluid flowed in from a supply part to a distribution part communicated with a water receiving part through a plurality of distribution heads(31c), and a buffing part for preventing water hammer. The distribution head part includes a case(31a) for the distribution head part having plurality of perforations, an inlet port(31b) connected to a main pipe at a side of the case, and the plurality of distribution head which is at right angle to the inlet port. The buffing part includes a piston(32b) and a case(32a) for the buffing part having an installation and a moving spaces for the piston, wherein the fluid is flowed in a side of the piston from the distribution head part and a buffing unit(32d) is installed to the other side of the piston.
Patent KR-20030004986-A (KR)
Inventor: HISADA TOMOYUKI
IPC: G06Q10/00
Filed: 2002-02-27
Abstract: PURPOSE: To enhance social safety by facilitating introduction of a security system. CONSTITUTION: A terminal system 1 having a mass spectrometric means and performing inspection of a dangerous article is installed in an inspection yard, and an assist system 2 for judging the presence and the kind of a dangerous article based on the mass spectrometric data of an component being measured by the mass spectrometric means is installed at the office of a security service company such that information can be exchanged between them through a communication network 3. The assist system 2 transmits the decision results and processing guidance of a dangerous article to the terminal system 1 through the communication network 3. Since facility management, e.g. maintenance and inspection, and operation management of the entire security system are performed by the security service company, a user can introduce the security system easily.
Patent KR-20030071102-A (KR)
Title: Noncontact type 3-dimensional scanning method using automatic moving apparatus
Inventor: HAN CHANG SEOK
IPC: H04N1/04
Filed: 2002-02-27
Abstract: PURPOSE: A contactless three-dimensional scanning method using an automatic transfer device is provided to perform the optimum three-dimensional scanning operation stably and rapidly using an automatic transfer device having a contactless distance measurement sensor. CONSTITUTION: A three-dimensional scanner is set(S1). An optimum distance between an object and a distance measurement sensor is set(S2). The object is automatically scanned vertically and horizontally according to the shape of the object(S3). A horizontal frame is moved to the left and right to repeat the automatic scanning(S4). When a new height appears while the automatic scanning is being carried out, a vertical frame is moved to set the scanner to the new height(S5).
Patent KR-20030017304-A (KR)
Title: Half-tone dot elimination method and system thereof
Inventor: FUJIMOTO KATSUHITO
IPC: G06V30/10
Filed: 2002-02-28
Abstract: PURPOSE: To extract a character suitable for character recognition. CONSTITUTION: After an original image including the character with half-tone dot meshing is input and a prescribed processing is carried out, a sequence pattern of black picture elements is extracted in a processing-objective area. When the extracted pattern has a prescribed concentration or more, it is judged as a half-tone-dot-meshed portion, and average values and standard deviations are calculated in lateral and longitudinal sizes of the sequence pattern. A threshold value is calculated based on the average values and standard deviations to remove a half-tone-dot-meshed pattern. A pattern having a long outline compared with the included black picture element is removed as unnecessary pattern out of the residual sequence pattern, and a protruded portion generated in the character is eliminated at last to finish the extraction of the character.
Patent KR-20030075523-A (KR)
Title: Equipment for hardening Sealant
Inventor: JUNG SEONG SU
IPC: G02F1/13
Filed: 2002-03-19
Abstract: PURPOSE: A sealant curing device is provided to form top surfaces of supporting parts fixed in a chamber in the flat surface structure for increasing the contact surface between joined surfaces and the supporting parts, thereby preventing the local depress. CONSTITUTION: A sealant curing device includes a chamber(10), a plurality of supporting bars(30) formed in the chamber and having a top surface in the flat surface structure with holes(35) at side surfaces at both ends, and fixing parts(50) each of which a side is fixed to the inside of the chamber and the other side is inserted into the holes of the supporting bars. The fixing parts respectively have a circular section.
Patent KR-20030076005-A (KR)
Title: welding machine for synthetic fiber
Inventor: CHOE JEONG HYEON
IPC: D06H5/00
Filed: 2002-03-22
Abstract: PURPOSE: A fusing device of synthetic resin fabric is characterized by transferring a moving body on following a beam, hydraulic controlling an injection angle of a hot-blast nozzle and height of pressure roller with a control console and installing the plural pressure rollers. The fusing device is capable of applying to the synthetic resin fabrics having various widths and having excellent workability. CONSTITUTION: The fusing device of the synthetic resin fabric is comprised of: the guide beam(3); the moving body(10) adjusting a position in accordance with a length of the beam(3); the hot-blast nozzle(18) installed on the moving body(10), injecting hot-blast to the synthetic resin fabric; and the pressure roller(26) pressing the fabric.
Patent KR-20020077141-A (KR)
Inventor: HIROOKA HIROSHI
IPC: D06F37/42
Filed: 2002-03-27
Abstract: PURPOSE: To obtain a lid lock of a washing machine that locks and releases a lid by moving a locking pin between an engagement position and a release position by energizing separately two electromagnetic coils arranged in parallel, that does not necessitate provision of tight closure, can be arranged even in a small space below a top cover, and helps easily, inexpensively and reliably detect the movement of a plunger to the engagement position or the release position. CONSTITUTION: The lid lock of a washing machine is comprised of first and second electromagnetic coils 9 and 10 moving a plunger 17 provided with a locking pin 18 at the tip, to an engagement position and a release position, first and second permanent magnets 14 and 15 holding in the engagement position and the release position, and a spring 26 as an energized member energized by the contact of the plunger 17 when the plunger 17 moves to the engagement position or the release position is fitted, and lid locking is detected from a change in output voltage due to energization and deenergization.
Patent KR-20030079384-A (KR)
Title: Air supplier in fluid contact type
Inventor: BAE SUN HEE
IPC: B05B7/06
Filed: 2002-04-04
Abstract: PURPOSE: A gas-liquid contact type air supplying device is provided in which fluid passing through gas-liquid supplying unit is instantaneously dispersed in the natural state, the fluid is smoothly flown by flow rate of water, and the fluid passing through the gas-liquid supply unit is moved far away. CONSTITUTION: In a gas-liquid contact type air supplying device comprising an inner pipe(20) through which liquid passes, on one side of which water passing hole is formed, and in which the outer circumferential surface(12) of the water passing hole is closed; and an outer pipe(40) which is tightly connected to the outer surface of the inner pipe, and at a certain position of the upper surface of which air inlet(30) is formed so that air is introduced through the air inlet, the gas-liquid contact type air supplying device further comprises a shaft(60) connected to motor(50) arranged at a certain position on the outer circumferential end of the outer pipe and connected in a length direction of the outer pipe, and screws(70) installed on the shaft and consisted of a plurality of blades, wherein the screw is consisted of at least two or more blades, and wherein at least one or more screws are installed on the shaft.
Patent KR-20030081759-A (KR)
Inventor: KWAK JONG TAEK
IPC: G01C21/30
Filed: 2002-04-12
Abstract: PURPOSE: A navigation method and a navigation system are provided reduce power consumption and to improve an electric noise characteristic by varying selectivity of an input frame depending on a moving speed of an optical mouse. CONSTITUTION: An electric signal representing a location of an optical sensor is generated after frames having navigation information are provided. Then, first frame is stored in a reference frame memory as a reference frame(S1). An input frame following the first frame is stored in an input frame memory(S2). A mask window having a predetermined size is set in the reference frame(S3). Relative values are found by moving the mask window along the input frame one by one pixel(S4). Then, a displacement value of an X-axis and a Y-axis is calculated at a location, where the relative value is a highest level(S6). Then, a selection period of the input frame is controlled after determining the speed of an optical sensor(S7).