• 대한기계학회논문집
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• 제9권4호
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• pp.440-451
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• 1985

본 논문에서는 곡면절삭력계의 해석을 통하여 절삭성과 내마멸성이 우수한 공 구기하형상과 곡면절삭과정에서 절삭조건에 따라 변화하는 가공정밀도 및 안정성을 규 명하고자 한다.

• 한국광학회지
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• 제12권4호
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• pp.334-338
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• 2001

피조 간섭계의 측정 정밀도를 향상시키기 위해서 광 분할기를 제거한 형태의 피조 간섭계를 구현했다. 단일 모드 광섬유를 구면파 광원으로 사용했고 끝 단을 반사면으로 만들기 위해서 경면 가공했다. 반사면은 적당한 각도로 경사지게 가공되어 있는데 이것은 간섭무늬의 CCD관찰을 용이하게 한다. 경사 단면 광섬유 광원을 이용한 피조 간섭계는 기존의 피조 간섭계에서 구면파를 왜곡시키는 광 분할기를 제거함으로써 측정 정밀도를 향상시킬 수 있었다 또한 동일한 시편의 측정결과를 비교함으로써 기존의 피조 간섭계로부터 개선된 정밀도를 정량적으로 구할 수 있었다. 그리고 경사 단면 광섬유 광원의 구면파정도를 알아보기 위해서 PS/PDI(Phase Shifting/Point Diffraction Interferometer)를 구현함으로써 광원의 구면파 정도를 실험적으로 검증했다.

• Journal of information and communication convergence engineering
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• 제14권1호
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• pp.21-25
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• 2016

N-screen is a promising technology to improve support for multimedia multicasting, content sharing, content mobility, media scalability, and seamless mobility. In this paper, the WiMedia distributed-MAC (D-MAC) protocol is adopted for development of a seamless N-screen wireless service. Furthermore, to provide a multi-hop, one source multi-use N-screen service through point to point streaming in a seamless D-MAC protocol, a dynamic multi-frame transmission technology is proposed. In this technology, a dynamic time slot allocation scheme and a multi-hop resource reservation scheme are combined. In the proposed dynamic time slot allocation scheme, two thresholds, a hard threshold and a soft threshold, are included to satisfy the power consumption and delay requirements. A multi-frame DRP reservation scheme is proposed to minimize end-to-end delay during the multi-hop transmissions between N-screen devices. The proposed dynamic multi-frame transmission scheme enhances N-screen performance in terms of the multi-hop link establishment success rate and link establishment time compared to the conventional WiMedia D-MAC system.

• 한국자동차공학회논문집
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• 제6권2호
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• pp.80-91
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• 1998

In this paper, the estimation of dynamic interlaminar fracture toughness on fracture mode II in CFRP(carbon fiber reinforced plastics) laminates in made. Dynamic ENF(End Notched Flexure) apparatus used in this paper is manufactured by suing Split Hopkinson Pressure Bar. The static and impact load history in the CFRP specimen is measured by using manufactured dynamic ENF tester and 3-point bending test is carried out to find the load history. Also dynamic interlaminar fracture toughness can be found by using the J integral obrained from dynamic analysis in consideration of intertia-force effect.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 추계학술대회 논문집
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• pp.149-153
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• 2001

This paper presents an end-point control of 1-link flexible arm tip-mass by using fuzzy position control algorithm. The arm is mounted on a translational mechanism driven by a ballscrew, whose rotation is controlled by a DC servomotor. Tip position is controlled so that it follows a desired position. Feedback signal is composed of both tip displacement error and change of error. This paper gives tip responses according to the variations of tip-mass and beam length, and the effects of reducing the residual vibrations occurring at the end-point. In the case of the residual vibrations of tip displacement, fuzzy control has better results than the PD-control.

• Journal of applied mathematics & informatics
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• 제28권1_2호
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• pp.411-423
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• 2010

In this paper, a numerical method for singular perturbation problems arising in chemical reactor theory for general singularly perturbed two point boundary value problems with boundary layer at one end(left or right) of the underlying interval is presented. The original second order differential equation is replaced by an approximate first order differential equation with a small deviating argument. By using the trapezoidal formula we obtain a three term recurrence relation, which is solved using Thomas Algorithm. To demonstrate the applicability of the method, we have solved four linear (two left and two right end boundary layer) and one nonlinear problems. From the results, it is observed that the present method approximates the exact or the asymptotic expansion solution very well.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.1830-1831
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• 2006

In this paper, the search is conducted along each of the coordinate directions for finding the minimum. If $e_i$ is the unit vector along the coordinate direction i, we determine the value a, minimizing f(a)= $f(x+ae_i)$, where a is a real number. A move is made to the new point $x+a_ie_i$ at the end of the search along the direction i. In an n dimensional problem, we define the search along all the directions as one stage. The function value at the end of the stage is compared to the value at the beginning of the stage in establishing the convergence. The gradient appears to be zero at point. We can safeguard this by introducing an acceleration step of one additional step along the pattern direction developed by moves along the coordinate directions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1036-1041
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• 1993

The tip of the flexible robot arm has to be controlled by the active control reducing vibration because it has residual vibration after getting to desired position. This paper presents an end-point position control of a 1-link flexible robot arm having tip mass by the PID control algorithm. The system is composed of a flexible arm with tip mass, dc servomotor and ballscrew mechanism under translational motion. The feedback signal composed of the tip displacement measured by laser sensor, estimated velocity and acceleration is used to control the base motion. Theoretical results are obtained by applying the Laplace transform and the numerical inversion method to the governing equations. After the flexible robot arm reaches to. the desired position, the residual vibration is controlled by the PID algorithm. This paper gives the simulation and experimental results of end-point responses according to changing tip-mass and arm length. And this algorithm shows good effects of reducing the residual vibration. Approximately, theoretical response is in good agreement with experimental one.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1360-1363
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• 1996

EPD(End Point Detection) is used to decide etching degree of layer which must be removed at wafer etching process in plasma etching process which is one of the most important process in semiconductor manufacturing. In this thesis, the method which detects malfunction of etching process in real-time will be discussed. Several EPD signal traces are collected in normal plasma etching condition and used as reference EPD signal traces. Critical points can be detected by applying differentiation and zero-crossing techniques to reference EPD signal. Mean and standard deviation of critical parameters which is memorized from reference EPD signal are calculated and these determine the lower and higher limit of control chart. And by applying statical control chart to EPD signals which are collected in real etching process malfunctions of process are detected in real-time. By means of applying this method to the real etching process we prove our method can accurately detect the malfunction of etching process and can compensate disadvantage of current industrial method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.16-18
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• 2009

VoIP(Voice over IP) is the technology to transport voice and video over IP networks such as Internet. Today, VoIP technology is viewed as the right choice for provide voice, video, and data communication over next generation network. We are sure that the multipoint VoIP will help enhancing the various application services in ubiquitous environment. The paper shows multipoint VoIP system implemented with end-point mixing model and introduces various embedded systems such as UFC(Ubiquitous Fashionable Computer), tourist guide terminal and industrial terminal which use the multipoint VoIP.