• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1043-1044
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• 2013

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1767_1768
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• 2009

4-step 알고리즘을 이용하여 3차원 이미지 위상 정보를 분석하였다. Carre(1966)에 의하여 제시된 위상 분석 기술은 위상이동에 대하여 설명하고 있다. Wyant(1982)에 의한 4-step 알고리즘은 수많은 PSI(Phase-Shift Interferometry)법[1] 중에서 가장 일반적인 내용이다. 그러나 실험장비 설치 시, 매우 어렵다는 단점이 있다. 실험 과정에서 물체의 3차원 형상을 얻기 위해 매우 간단히 실험 설치를 하였다. 간섭 패턴은 추가적인 렌즈, 거울, 모터와 같은 광학장비 없이 랩뷰 프로그램과 비젼 시스템을 사용하여 구축하였다. 4-step method와 컴퓨터 프로그램에 의해 생성된 unwrapping image에 의해 물체의 wrapped된 이미지를 얻었다. 실험에 의하여 얻어진 간섭패턴을 분석 함으로써, 웨이브 프론트, 강도 그래프, 3차원 형상, 상수 데이터와 같은 다양한 정보를 얻을 수 있었다.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.1-10
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• 2007

A two-dimensional backward facing step flow was comptuted using a Detached Eddy simulation(DES) based on the SST turbulence model. The expansion ratio(ER) was 1.125 and the Reynolds number based on the step height and the mean velocity in the upstream channel was 37,500. The flow condition was the same as with the experimental research[1]. The reattachment length, oscillatory characteristics of the flow and the coherent structures of the present simulation were compared to demonstrate the improtance of spanwise grid spacing.

• The Journal of Korea Robotics Society
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• v.2 no.1
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• pp.55-63
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• 2007

Mobile robots traveling on rough terrain need several algorithms to overcome obstacles. In this paper, we propose the step-type obstacle traversal algorithm to adapt the mobile robot with six arms and wheels to travel on rough terrain. Obstacle traversal is composed of two different stages: planning and control. In planning stage, the required joint torque of each arm as well as the interference between the wheels and the arms are analyzed to guarantee traversing obstacles. Control stage includes such steps as checking distance to obstacle, determining the height and length of obstacle, performing arm motion according to sensed torque data, and evaluating safety at every instance. The proposed algorithm is designed and implemented for CALEB 1 six legged robot developed in the laboratory and verified by simulation and experiment in outdoor environment.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.89.2-89
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• 2001

Wheel chair bound persons need assistance since there are many steps or curbs or other obstacles blocking their path in the roadways and walkways. Although a step may be small, it may be very difficult for such a person to climb over it. Therefore, we are proposing a power assist wheel chair robot that enables a wheel chair bound person to climb over steps up to about 10 centimeters in height without assistance from others. By using the proposed wheel chair robot, a user can maintain inverse pendulum control after raising its front wheels Then, a user can move forward to the step maintaining the inverse pendulum control, and can climb over the step using motor force of a rear wheel shaft ...

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.97-105
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• 2011

The purpose of this study was to investigate the kinetic factors of Stefan holm's take-off motion and provide the technical data. Collected data of the subject(height: 181 cm, weight: 71 kg, record: 230 cm) were used for the last two strides and take-off phase. The results were as follows: The vertical impulse force was 2044.8 N which was 2.49 times and the anterior-posterior impulse force was -1306.4 N which was 1.88 times of the subject's weight. The take-off leg angular velocities($\omega_x,\;\omega_y$) were switched drastically from clockwise to count clockwise direction between two-step touchdown and take-off. The highest jerk of the take-off foot was 368.97 m/s3 during the two step take-off and the take-off foot made an impact to the ground with 1225.07 m/s3 during the one step touchdown.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.251-259
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• 2010

It is presented in this study a new efficient intelligent machining strategy, which can be used to remove the uncut volume at the boundary region of curved surfaces caused by cutter interference. The geometric form definitions and recognition of topological features of the surface triangulation mesh are used to generate cutter paths along successive and interconnected steepest pathways, that minimize the cusp height left after flat end milling. In order to machine the uncut volume gradually, the z-map cutter centers are adjusted to avoid cutter interference for the 6 kinds of avoidance types. And then, the generative subsequent paths are sequenced to determine the second step cutter paths for the next uncut volume. For the 2 kinds of test models with convex and concave surface region, the implemented software algorithm is evaluated by investigating the residual swelling of uncut volume for each machining step.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.30.1-30
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• 2001

This paper describes a new cooperative strategy for two wheelchairs to climb a step. These two wheelchairrobots are connected with a simple linkage mechanism between the rear of one wheelchair and the front of another. Two wheelchair robots climb a step one after the other. In this research, We did not use a method by Which a robot lifts up and supports its weight using any special actuator but a method of handling the robot's moment of rotation by the force of the link which come from the assisting robot. This method is especially influenced by the height of the two robot's link positions. So we study this method from the viewpoint of changing the two-link positions....

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.129-133
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• 2001

In this paper, hermetic sealing was studied fur wafer level packaging of the MEMS devices. With the flip-chip bonding method, this B-stage epoxy sealing will be profit to MEMS device sealing and further more RF-MEMS device sealing. B-stage epoxy can be cured 2-step and hermetic sealing can be obtained. After defining $500{\mu}{\textrm}{m}$-width seal-lines on the glass cap substrate by screen printing, it was pre-baked at $90^{\circ}C$ for about 30 minutes. It was then aligned and bonded with device substrate followed by post-baked at $175^{\circ}C$ for about 30 minutes. By using this 2-step baking characteristic, the width and the height of the seal-line were maintained during the sealing process. The height of the seal-line was controlled within $\pm0.6${\mu}{\textrm}{m}$ and the strength was measured to about 20MPa by pull test. The leak rate of the epoxy was about $10^7$ cc/sec from the leak test.

• Transactions of Materials Processing
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• v.16 no.6
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• pp.457-462
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• 2007

The drawbeads, which are used for controlling the flow of the sheet into die cavity by imposing the tension and for preventing the forming defects like wrinkling, springback, etc. during the sheet forming process, affect the formability strongly because of the differences in the restraint and opening forces according to the drawbead shapes and dimensions. In this study, the experimental device enabling to measure the drawbead restraining and opening forces is manufactured and the drawing forces of circular, square, and step drawbeads are measured. The drawbead restraining and opening forces of a circular drawbead are increased as its drawbead height is increased. Similarly, those of a square drawbead are increased as its height is increased and shoulder radii decreased. The drawbead forces obtained from the experiment were compared with those calculated in the numerical simulation of stamping process of automotive fender. Good agreement was found so that the experimental measurements can be used in the simulation of auto-body stamping process.