• 전기학회논문지
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• 제57권2호
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• pp.256-260
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• 2008

The Ring Laser Gyro makes use of the Sagnac effect within a resonant ring cavity of A He-Ne laser and has more accuracy than the other Gyros. The Low Earth Orbit satellite for observatory use require the high accuracy Gyro to control and determine the altitude because of the need of payload pointing accuracy. In this paper, The theory of the Path Length Control is explained. The electrical design of Path Length Controller is described. The Design for Path Length Controller is composed of the demodulator, Integrator, Phase shifter, High Voltage Amplifier. We apply the circuit to 28cm square ring laser gyro and get the test results.

• 전기학회논문지
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• 제57권9호
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• pp.1584-1588
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• 2008

The Ring Laser Gyroscope makes use of the Sagnac effect within a resonant ring cavity of a He-Ne laser and has more accuracy than the other gyros. The Low Earth Orbit satellite for observatory use require the high accuracy Gyro to control and determine the altitude because of the need of payload pointing accuracy. In this paper, The theory of the Path Length Control is explained. The electrical design of Path Length Controller is described. The Design for Path Length Controller is composed of the demodulator, integrator, phase shifter, high voltage amplifier. We apply the circuit to 28cm square ring laser gyro and get the test results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.692-695
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• 1997

Nonlinear robust attitude controller for 3-axis stabilized spacecraft is designed. Robust stability analysis for nonlinear spacecraft system with disturbance is conducted. External disturbances and parametric uncertainties decrease Spacecraft's attitude pointing accuracy. Sliding Mode Control(SMC) provides stability of system in the face of these disturbances and uncertainties. The concept of quadratic boundedness and quadratic stability are applied to the robust analysis for the nonlinear spacecraft system subject to bounded disturbance torques. Numerical simulation is conducted to compare the analysis result and actual nonlinear simulation. The simulation show that analysis result is valid.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1103-1106
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• 1996

Disturbance Accommodating Attitude control logic for 3-axis stabilized spacecraft is designed and compared with PIID control logic. PID controller provide the zero steady error for constant disturbances. PIID controller detect and cancel disturbances upto the ramp input. PID control logic is designed as the main control logic. We designed the disturbance observer to detect the effect of disturbance using the sinusoidal function. The detected disturbance are compensated by the additional control logic. The comparison simulation is conducted between PIID and PIID with DAC. The simulation results show that PIID with DAC shows the better attitude pointing accuracy.

• 항공우주시스템공학회지
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• 제16권5호
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• pp.49-56
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• 2022

S-STEP 은 관심 지역의 시한성 긴급 표적 및 군사적 이상 징후를 감시하기 위한 초소형 SAR 위성 임무로, 고도 510 km의 저궤도에 32 대의 위성군을 배치하여 관심 지역에 대해 평균 재방문 주기를 30 분 이하로 달성한다. S-STEP의 임무 운용 모드는 표준 모드, 관측 모드, 통신 모드, 궤도유지 모드 등으로 구분되며, 이에 따라 자세 기동 모드 역시 초기 각속도 안정화, 태양 지향, 목표지점 및 지상국 지향, 추력 방향 유지 등으로 세분화된다. 이 연구에서는 S-STEP 임무 운용 시나리오의 예비 설계 결과와 위성체의 특성을 바탕으로 초기 각속도 안정화 및 태양 지향 모드와 관측 궤도 운용 모드에서의 자세 성능을 분석하였다. 분석 결과, 할당된 시간 이내에 필요한 자세 제어를 완료하여 각 모드에서 요구되는 자세 제어 정확도를 달성함을 확인하였다.

• Journal of Korean Neurosurgical Society
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• 제59권3호
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• pp.322-324
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• 2016

To introduce a new device for catheter placement of an external ventricular drain (EVD) of cerebrospinal fluid (CSF). This device was composed of three portions, T-shaped main body, rectangular pillar having a central hole to insert a catheter and an arm pointing the tragus. The main body has a role to direct a ventricular catheter toward the right or left inner canthus and has a shallow longitudinal opening to connect the rectangular pillar. The arm pointing the tragus is controlled by back and forth movement and turn of the pillar attached to the main body. Between April 2012 and December 2014, 57 emergency EVDs were performed in 52 patients using this device in the operating room. Catheter tip located in the frontal horn in 52 (91.2%), 3rd ventricle in 2 (3.5%) and in the wall of the frontal horn of the lateral ventricle in 3 EVDs (5.2%). Small hemorrhage along to catheter tract occurred in 1 EVD. CSF was well drained through the all EVD catheters. The accuracy of the catheter position and direction using this device were 91% and 100%, respectively. This device for EVD guides to provide an accurate position of catheter tip safely and easily.

• Journal of Astronomy and Space Sciences
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• 제17권2호
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• pp.211-220
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• 2000

Korea Astronomy Observatory(KAO) is working to retrofit its 1m robotic telescope in collaboration with a company (ACE, Astronomical Consultants & Equipment). The telescope system is being totally refurbished to make a fully automatic telescope which can operate in both interactive and fully autonomous robotic modes. Progress has been made in design and manufacturing of the telescope mount, mechanics, and optical performance system tests are being made for re-configured primary and secondary mirrors. The optical system is designed to collect 80% incident light within 0.5 arcsec with f/7.5 Ritchey-Chretien design. The telescope mount is an equatorial fork with a friction drive system. The design allows fully programmable tracking speeds with typical range of 15 arcsec/sec with accuracy of $\pm5$ arcsec/hour. The mount system has integral pointing model software to correct for refraction, and all mechanical errors and misalignments. The pointing model will permit positioning to better than 30 arcsec RMS within $75^{\circ}$ from zenith and 45 arcsec RMS elsewhere on the sky. The software is designed for interactive, remote and robotic modes of operation. In interactive and remote mode the user can manually enter coordinates or retrieve them from a computer file. In robotic mode the telescope controller downloads the coordinates in the order determined by the scheduler. The telescope will be equipped with a CCD camera and will be accessible via the internet.

• 한국전문물리치료학회지
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• 제13권4호
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• pp.23-29
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• 2006

The purpose of the present study was to examine gaze effects on spatial and kinematic characteristics during a pointing task. Subjects were asked to watch and point to an aimed target (2 mm in diameter) displayed on a vertically mounted board. Four gaze conditions were developed as combinations of "seeing-aiming" in terms of the eye movements: Focal-Focal (F-F), Focal-Fixing (F-X), Fixing-Focal (X-F), and Fixing-Fixing (X-X). Both the home target and an aimed target were presented for 1 second and then were disappeared in F-F and X-F. In X-F and X-X, only an aimed target disappeared after 1 second. Subjects were asked to point (with index finger tip) to an aimed target accurately as soon as the aimed target was removed. A significant main effect of gaze was found (p<.01) for normalized movement time. Peripheral retina targets had significantly larger absolute error compared to central retina targets on the x (medio-lateral) and z (superior-inferior) axes (p<.01). A significant undershooting to peripheral retina targets on the x axis was found (p<.01). F-F and X-F had larger peak velocities compared to F-X and X-X (p<.01). F-F and X-F were characterized by more time spent in the deceleration phase compared to F-X and X-X (p<.01). The present study demonstrates that central vision utilizes a form of on-line visual processing to reach to an object, and thus increases spatial accuracy. However, peripheral vision utilizes a relatively off-line visual processing with a dependency on proprioceptive information.

• Journal of Power Electronics
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• 제2권1호
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• pp.25-31
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• 2002

Servo drives with microcomputer control provide the possibility of using modern and sophisticated control algorithms. As an additional feature it is possible to implement parallel and/or redundant software and hardware structures to realise safe motion or similar security functions. Unfortunately microcomputer control also has some impact on the behaviour of servo drives. Control algorithm, cycle time, sensors and interface have to be perfectly synchronised. Special control schemes are necessary on the line side (power supply) to meet the actual requirements concerning EMC. This contribution presents experiences and results obtained from a modern digital drive system pointing out the influences of low and high accuracy position sensors and the interdependencies mentioned above.

• 감성과학
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• 제10권4호
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• pp.583-601
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• 2007

웨어러블 컴퓨팅 환경은 대개 이동 중일 가능성이 많고 이때 눈과 손이 자유롭지 못하고 많은 주의가 필요한데 기존의 데스크탑 인터페이스 방식(WIMP)은 적합하지 않다. 또한 웨어러블 환경에서 모바일 기기의 소형화로 인하여 작은 화면에서 정보를 확인하고 처리해야 하기 때문에 기능 수행에 따른 인지부하가 늘어남과 동시에 수행 속도가 느려지고 많은 오류가 발생하는 등 어려움이 따른다. 이와 같이 변화된 환경에 적합한 입력 방식의 적정 수준을 찾는 연구가 필요하다. 본 연구는 이동 상황에서 모바일 기기를 사용할 때 동시에 여러 가지 일을 수행함으로써 걸릴 수 있는 인지부하를 줄여주기 위한 방법을 기기의 입력 방식과 사용되는 메뉴구조의 복잡성을 중심으로 분석하였다. 입력 방식을 포인팅입력 방식, 버튼입력 방식, 동작입력 방식으로 나누고, 이 방식들을 통한 메뉴탐색 과제와 화면에 제시되는 도형기억 과제를 동시에 수행했을 때 수행의 정확도와 과제수행 속도를 측정하였다. 또한 제시되는 메뉴탐색 과제의 메뉴계층의 수를 변화시켜서 입력 방식의 복잡성에 따른 과제 수행을 살펴보았다. 실험은 정지 상황과 이동 상황에서 모두 이루어졌다. 정지 상황과 이동 상황 모두에서 포인팅입력 방식이 과제 수행의 정확도가 가장 높은 반면 수행 속도에서 가장 느린 것으로 나타났다. 동작입력 방식에서는 수행의 정확도는 떨어졌으나 수행 속도는 빠르게 나타났다. 이는 이동 중에 수행되는 과제에서 정확도보다도 속도가 중요한 상황에서는 동작입력 방식이 적합하다는 것을 시사한다.