• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
• /
• pp.428-433
• /
• 1994

This investigates the feasibility of applying fuzzy ogic controllers to the motion tracking control of a direct drive robot manipulator to deal with highly nonlinear and time-varying dynamics associated with robot motion. A fuzzy logic controller with narrow shape of membership functions near zero and wide shape far away zero is analyzed. Simulation and experimental studies have been conducted for a 2 degree of freedom direct drive SCARA robot to evaluate control performances, Fuzzy logic controllers have shown control performances that are often better, or at least, as good as those of conventional PID controllers. Furthermore, the control performance of fuzzy logic controllers can be improved by selecting membership functions of narrow shapes near zero and wide shapes far away zero.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2001년도 학술대회 논문집
• /
• pp.98-101
• /
• 2001

This work presents racetrack High Temperature Superconducting (HTS) magnet with iron plates to achieve the maximum current-carrying capacity and the simple shape that can easily be wound and jointed. The shape, position and kinds of iron plates are chosen by using 3 Dimensional Finite Element Analysis (3d FEA) considering magnetic saturation of iron plates. The racetrack HTS magnet with iron plates, magnet having optimized current distribution and initial magnet are compared with each other through 3D FEA, manufacturing and testing these magnets. The measured performance of the magnet with iron plates improved by 50% on the basis of initial magnet.

• Journal of Information Display
• /
• 제4권4호
• /
• pp.13-18
• /
• 2003

One of the most important issues in AC PDP is the improvement of luminous efficiency. One possible method for achieving this aim is by increasing Xe partial pressure in discharge gas mixture. The increase of Xe ratio, however, causes the driving voltage to rise, even if brightness is increased. In this study, a new electrode shape is proposed. A test panel fabricated by using a new electrode shows that efficacy has improved by 25 % and sustain voltage has decreased by 20 % compared with the conventional structure.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
• /
• pp.347-350
• /
• 2003

Optimization of the luminance, luminous efficiency, and address voltage margin characteristics has been made on the delta color array PDP with various hexagonal shape subpixels. The optimal subpixel and electrode designs are obtained for the 42-inch high-definition PDP ($1,366{\times}768$) with the fine pixel pitch less than 0.7 mm. The hexagonal delta array structure shows more improved characteristics than that of the normal delta array structure with rectangular shape subpixels.

• Journal of Information Technology Applications and Management
• /
• 제9권3호
• /
• pp.1-12
• /
• 2002

Due to the fast development in computer and communication technologies, a video is now being more widely used than ever in many areas. The current information analyzing systems are originally built to process text-based data. Thus, it has little bits problems when it needs to correctly represent the ambiguity of a video, when it has to process a large amount of comments, or when it lacks the objectivity that the jobs require. We would like to purpose an algorithm that is capable of analyze a large amount of video efficiently. In a video, divided areas use a region growing and region merging techniques. To sample the color, we translate the color from RGB to HSI and use the information that matches with the representative colors. To sample the shape information, we use improved moment invariants(IMI) so that we can solve many problems of histogram intersection caused by current IMI and Jain. Sampled information on characteristics of the streaming media will be used to find similar frames.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
• /
• pp.545-546
• /
• 2006

A problem of oil supply for a reciprocating compressor is very significant for an evaluation of reliability. Since a rotational motion of a crank shaft for the reciprocating compressor with small capacity is used for a power source of oil supply, a centrifugal force of the rotational shaft provides a stroke of oil inside the shaft like a centrifugal pump. The pumped oil rises following an inner wall and provided to a bearing passed through an oil supply hole at the side of the shaft for lubrication of the bearing. In this study, the amount of oil supply has been investigated by a numerical analysis for various conditions such as a shape of a groove, rpm of the compressor, and a shape of a flow channel. Also, a method of increasing oil supply for a low rpm has been studied so that the function can be improved for a variable condition.

• 한국유체기계학회 논문집
• /
• 제14권5호
• /
• pp.55-62
• /
• 2011

Shape optimization of a Printed circuit heat exchanger (PCHE) has been performed by using three-dimensional Reynolds-Averaged Navier-Stokes (3-D RANS) analysis and surrogate modeling techniques. The objective function is defined as a linear combination of effectiveness of the PCHE term and pressure drop in the cold channels of the PCHE. The cold channel angle and the ellipse aspect ratio of the cold channel are used as design variables for the optimization. Design points are selected through Latin-hypercube sampling. The optimal point is determined through surrogate-based optimization method which uses 3-D RANS analyses at design points. The results of three types of surrogate model are compared each other. The results of the optimizations indicate improved performance in friction loss but low performance in effectiveness than the reference shape.

• 대한전자공학회논문지
• /
• 제8권6호
• /
• pp.17-24
• /
• 1971

본 논문에서는 임의의 형상을 가진 유전체 안테나에 대한 새로운 해석 방법을 기술한다. 이 방법에서는 분극 전류 및 뇌하 밀도의 개념을 종래의 Stratton-Chu 형식에 도입하고 산란 원칙에 따라 유전체 내의 전계강도에 대해 적분 방정식을 세웠다. 이 적분 방정식을 수치 계산법으로 풀기 위해 유전체의 체적을 세분하고 작은 구로서 등가적으로 표시한다. 따라서 이 방법에 의해서는 임의의 형상의 유전체 안테나의 해석이 가능하다. 이와같이 해서 유전체 내의 전계강도를 구하고 그 강도에 입각해서 안테나의 복사특성, 입력 임피이단스 및 유전체 손실들을 산출했다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2010년 춘계학술대회논문집
• /
• pp.55-59
• /
• 2010

Aerodynamic design optimization of rotor airfoil has been performed with advanced design method for improved aerodynamic characteristics of ONERA airfoils as a baseline. A multiple response surface method is used to consider various consider various constraints in rotor airfoil design. Airfoil surface and mean camber line are modified using various shape functions. Numerical simulations are performed using KFLOW, a Navier-Stokes solver with shear stress transport turbulence model. The present design method provides favorable configurations for the high performance rotor airfoil. Resulting optimized air foils give better aerodynamic performance than the baseline airfoils.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
• /
• pp.281-286
• /
• 2001

Titanium alloy conducted in this experimental study has superior corrosive resistant and is mainly used in aerospace, automotive and petro-chemical industries. It is also treated with important materials of domestic goods due to improvement of the standard of living. In this study specimens were processed in the wire EDM after annealing, solution treatment and aging. Results were obtained through repeated experments of main rough process and finish process with the change of process parameters. Processing characteristics such as surface hardness, surfaces roughness, shape of processed surface and components were measured. The results confirmed that the above mentioned elements were improved in accordance with the number of process. Therefore, the optimal wire EDM condition in accord with processing characteristics is proposed in this experiment.