• Bulletin of the Korean Space Science Society
• /
• 2009.10a
• /
• pp.24.3-24.3
• /
• 2009

한국천문연구원에서 개발 중인 외계행성 탐색 시스템은 우리은하 중심부 $4^{\circ}\times4^{\circ}$ 영역을 10분 간격으로 시계열 관측하여 지구형 외계행성을 검출하는 시스템으로써, 대용량의 관측자료를 처리하기 위하여 영상차감법을 사용한다. 이 방법은 최적화 방법을 이용하여 기준영상과 관측영상사이의 점퍼짐함수 변화를 나타내는 커널을 구하고, 이를 적용하여 만든 합성영상과 관측영상을 서로 차감한 잔차영상에서 밝아지거나 어두워진 변광성을 찾아 내어 이들에 대한 구경측광 또는 점퍼짐함수 측광과정을 수행한다. 따라서 성단 및 은하중심부와 같이 별들이 밀집된 관측영역에 영상차감법을 이용하면 배경별들은 모두 제거되고 변광성만 남게 되므로 잔차영상의 분석을 통하여 변광성 검출 효율을 높일 수 있게 된다. 우리는 이 연구에서 구재림 등 (2007)에 의하여 수행된 산개성단 M11의 시계열관측 영상에 이 방법을 적용하여 얻은 새로운 결과와 기존 연구결과를 서로 비교하고, 변광성의 검출 효율과 측광 정밀도에 대하여 논의한다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1613-1616
• /
• 2005

In this paper, we developed an algorithm of generating cam contour curve for hinge mechanism of folder-type mobile phone. The main feature of this hinge mechanism is that we can operate uniform torque to open or close the mobile phone. We divided the opening or closing intervals of the cam into finite sub-intervals, and then we determined the cam contour curve of each sub-interval as a parabolic curve. Finally, these finite parabolic curves form the total cam contour. We can design single cam, which composed moving cam with contour curve and fixed cam that plays only roller, and twin cam with contour curve that is made up the pair of two cams symmetrically.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.9
• /
• pp.59-70
• /
• 2008

Polynomial is used to optimize crown bowl shape of a marine medium speed diesel engine piston. The primary goal of this paper is that it's for an original design through a thermal stress and highest temperature minimum. Piston is modeled using solid element with 6 design variables defined the positional coordinate value. Global optimum of design variables are found and evaluated as developed and integrated with the optimum algorithm combining genetic algorithm(GA) and tabu search(TS). Iteration for optimization is performed based on the result of finite element analysis. After optimization, thermal stress and highest temperature reduced 0.68% and 1.42% more than initial geometry.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.1133-1137
• /
• 1995

This paper presents a numerical method of the global search for an optimal geometric path for a manipulator arm amid obstacles. Finite term quintic B-splines are used to describe an arbitrary point-to-point manipulator motion with fixed moving time. The coefficients of the splines span a linear vector space, a point in which uniquely represents the manipulator motion. All feasible geometric paths are searched by adjusting the seed points of the obstacle models in the penetration growth distances. In the numerical implementation using nonlinear programming, the globally optimal geometric path is obtained for a spatial 3-link(3-revolute joints) manipulator amid several hexahedral obstacles without simplifying any dynamic or geometric models.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.2
• /
• pp.63-70
• /
• 2009

This paper proposes a novel path finding approach of a mobile robot using RF strength in sensor network. In the experiments based on the proposed method, a mobile robot attempts to find its location, heading direction and the shortest path in the indoor environment. The experimental system consisting of mesh network shares node data and send them to base station. The triangulation and the proposed Grid method calculate the location and heading angle of the robot. In addition, the robot finds the shortest path by using the base station attached on it to receive data of environment around each node. Kalman filter reduces the straight line error when the robot estimates the strength of received signal. The experimental results show the effectiveness of the proposed algorithm.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2016.10a
• /
• pp.123-124
• /
• 2016

본 연구는 스마트폰 사용자가 응급상황에 처했을 때 사용자의 정확한 위치 정보를 응급 구조 센터에 전달할 수 있는 방법을 개발함에 목적을 둔다. 사고의 경우 실외 뿐만 아니라 실내에서 많은 사고가 발생하는데, 일반적으로 위치 정보를 획득에 사용되는 GPS 의 경우는 실내 위치를 정확하게 파악하기 어렵기 때문에 구조를 지연시키는 문제를 야기한다. 본 연구는 이러한 상황들을 방지하기 위해 GPS와 와이파이, 블루투스를 각각 이용한 삼각 측량법을 통해 실내의 위치정보를 측정하고 더 나아가 압력센서를 통해 사용자의 위치를 3차원적으로도 탐색한다. 실험 결과, GPS를 이용하는 것보다 블루투스를 이용하는 것이 더 정확한 실내 정보를 탐색하는 것을 알 수 있었다. 또한 압력계를 통해 고도를 측정함으로써 건물 내부에서 사용자의 수직적 위치를 측정할 수 있었다. 이러한 결과는 위도 경도의 정확한 정보와 함께 고도에 대한 예측을 가능하게 함으로써 보다 정확한 실내 위치 정보를 획득하여 골든 타임을 확보하는데 도움이 될 것으로 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.11C
• /
• pp.917-924
• /
• 2008

Motion estimation and compensation in the spatial domain check the searching area of specified size in the previous frame and search block to minimize the difference with current block. When we check the searching area, it consumes the most encoding times due to increasing the complexity. We can solve this fault by means of motion estimation using shifting matrix in the transform domain instead of the spatial domain. We derive so the existed shifting matrix to a new recursion equation that we decrease more computations. We modify simply vertical shifting matrix and horizontal shifting matrix in the transform domain for motion estimation of half-pixel accuracy. So, we solve increasing computation due to bilinear interpolation in the spatial domain. Simulation results prove that motion estimation by the proposed algorithm in DCT-based transform domain provides higher PSNR using fewer bits than results in the spatial domain.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.11
• /
• pp.106-113
• /
• 1996

Using stainless steel as the cold forged parts especially the outer parts of automobile is gradually increasing because it can bear up against the erosion and the wear. During cold forging of the stainless steel the working pressure acting on die surface are very high therefore the wear on die surface can be greatly increased. In cold forging processes, die failure must be considered before die design. One of the main reasons of die failure in industrial application of metal forming technologies is wear. The die wear affects the tolerances of forged parts, metal flow and costs of processes etc. The only way to to control these failures is to develop methods which allow prediction of the die wear and which are suited to be used in the desing stage in order to optimize the process. In this paper, the rigid-plastic finite element method was combined with the wear prediction routine and then the forward extrusion process using stainless steel was analysed simultaneously. To minimize the die wear the FPS algorithm was applied and the optimal conditions of die configuration are suggested.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2007.05a
• /
• pp.353-356
• /
• 2007

chamfer 정합(matching)은 많은 응용분야에서 사용되온 에지(edge) 기반 정합기법으로, 변환된 모델에지와 영상에지간의 거리를 최소화하는 과정이다. 이 거리는 보통 거리변환을 이용하여 픽셀분해능으로 계산된다. 본 논문에서는 서브픽셀(subpixel) 거리계산을 위해 거리계산시 보간법을 사용하여, 정확한 chamfer 정합을 구현한, 개선된 chamfer 정합 방법을 제안한다. 또한, 보다 정밀한 정합을 위해, 최소거리를 갖는 픽셀위치의 주변영역을 이용하여 최적의 위치를 추정하지 않고, 서브픽셀로 실제 거리계산을 통해 최소 거리를 찾기 위해 Powell 의 최적화기법을 이용하였다. 실험결과는 제안된 방법의 타당성을 보여주었다.

• Journal of the Korea Concrete Institute
• /
• v.18 no.2 s.92
• /
• pp.151-159
• /
• 2006

The guide line of the SFRC mix design was not established, and the convenience of the practical application on the spot is not so good. In this paper, hence, the program which is optimized to result the mix proportion by the flexural strength and toughness, was developed to apply to SFRC on the practical spot. This program could minimize the number of trial mixes and get an economical and appropriate mixture. In addition, the theoretical background on which the program is based, will be the basis of the embodied method to mixing SFRC. Additionally, new algorithm, in this paper, was used to develop the mix proportioning program of SFRC. The new algorithm is the Harmony Search which is the heuristic method mimicking the improvisation of music players, Musical performances seek a best state determined by aesthetic estimation, as the optimization algorithms seek a best state determined by objected function value. And, it was developed the program about single fiber reinforced concrete, beside to the hybrid fiber reinforced concrete that two kinds of steel fibers, which have the different geometry, was reinforced. This will be able to keep the world trend to study, hence, offers the basis of the next research about hybrid fiber reinforced concrete.