• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1210-1215
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• 2010

The probe card are test modules which are to classify the good semiconductor chips and thin film before the packaging process. In the rapid growth a technology of semiconductor, the number of pads per unit area is increasing and pad arrays are becoming irregular. Therefore, the technology of probe card needs narrow width and lots of probe tip. In this paper, the probe tip based on the MEMS(Micro Electro Mechanical System)technology was developed a new MEMS probe tip for vertical probe card applications. For the structural designs of probe tip were performed to mechanical characteristics and structural analysis using FEM(Finite Element Method). Also, the contact force of MEMS probe tip compared with FEM results and experimental results. Finally, the MEMS probe card was developed a fine pitch smaller than $50{\mu}m$.

• Proceedings of KOSOMES biannual meeting
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• 2005.11a
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• pp.197-202
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• 2005

Generally, a semiconductor chip measured with a few micro units is captured by line scan camera for higher inspection accuracy. However, the faulty inspection requires an exact boundary detection algorithm because it is very sensitive to scan speed and lighting conditions. In this paper we propose boundary detection using subpixel edge detection method in order to increase the accuracy of bump faulty detection on chips. The bump edge is detected by first derivative to four directions from bump center point and the exact edge positions are searched by the subpixel method. Also, the exact bump boundary to calculate the actual bump size is computed by LSM(Least Squares Method) to minimize errors since the bump size is varied such as bump protrusion, bump bridge, and bump discoloration. Experimental results exhibit that the proposed algorithm shows large improvement comparable to the other conventional boundary detection algorithms.

• Journal of the Korea Computer Industry Society
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• v.5 no.1
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• pp.157-166
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• 2004

Consequently substantial research has been done on the development of the bio-metric recognition method as well as technical research in the field of authentication. As a method of bio-metric recognition, personal and unique information such as fingerprints, voice, face, Iris, hand-geometry and vein-pattern are used. The face image system in bio-metric recognition and information authentication reduces the denial response from the users because it is a non-contact system the face image system operates through a PC camera attached to a computer base this makes the system economically viable as well as user friendly. Conversely, the face image system is very sensitive to illumination, hair style and appearance and consequently creates recognition errors easily, therefore we must build a stable authentication system which is not too sensitive to changes in appearance and light. In this study, I proposed user authentication protocol to serve a confidentiality and integrity and to obtain a least Equal Error Rate to minimize the wrong authentication rate when it authenticates the user.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.5 s.311
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• pp.22-29
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• 2006

In this paper, we propose a block-based real-time people counting system that can be used in various environments including showing mall entrances, elevators and escalators. The main contributions of this paper are robust background subtraction, the block-based decision method and real-time processing. For robust background subtraction obtained from a number of image sequences, we used a mixture of K Gaussian. The block-based decision method was used to determine the size of the given objects (moving people) in each block. We divided the images into $6{\times}12$ blocks and trained the mean and variance values of the specific objects in each block. This was done in order to provide real-time processing for up to 4 channels. Finally, we analyzed various actions that can occur with moving people in real world environments.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.7
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• pp.801-806
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• 2004

Although the technology for emotion recognition is important one which demanded in various fields, it still remains as the unsolved problem. Especially, it needs to develop the algorithm based on human facial image. In this paper, we propose the facial image analysis algorithm for emotion recognition. The proposed algorithm is composed as the facial image extraction algorithm and the facial component extraction algorithm. In order to have robust performance under various illumination conditions, the fuzzy color filter is proposed in facial image extraction algorithm. In facial component extraction algorithm, the virtual face model is used to give information for high accuracy analysis. Finally, the simulations are given in order to check and evaluate the performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.326-326
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• 2008

갈륨 질화물 (GaN) 기반의 발광다이오드(Light Emitting Diode, LED)는 최근 디스플레이, 교동신호등, 휴대폰용 키패드의 광원 등에 널리 사용되는 전자소자로, 차세대 조명용 광원으로도 각광받고 있다. 일반적인 수평 구조의 LED에 비해 수직형 구조 LED 는 발광면이 n-GaN 표면 전체이며, 전류 확산 특성이 매우 뛰어남으로 인해 차세대 구조라고 표현되어 진다. 이런 구조에서 활성층 영역에서의 균일한 전류 분포는 전류밀집 현상을 억제하여 결과적으로 광학적 특성을 향상시킨다. 따라서 현재까지도 전류확산에 따른 발광다이오드의 성능향상에 대한 연구가 다각도로 이루어지고 있다. 본 연구에서는 수직형 GaN LED 의 전극 패턴에 따른 활성층 영역에서의 전류밀도 분포에 대해 조사하였다. 전극 패턴의 크기 및 구조 변화에 따른 활성층 영역에서의 전류분포도를 삼차원 회로 모델을 이용하여 분석하였다. 또한 활성층 영역으로 주입되는 전류 밀도의 크기가 내부양자효율에 미치는 영향에 대하여 알아보았다. 활성층 영역에서의 균일한 전류밀도 분포를 갖는 전극구조를 설계하였으며, 각각의 전극구조를 적용한 수직형 GaN LED의 전기/광학적 특성에 대해 전산모사 하였다. 최종적으로, n-GaN 위 전극의 크기 및 구조 변화에 대한 시뮬레이션 결과를 토대로, 균일한 전류분포 및 내부 양자효율 향상을 위한 전극패턴 설계 방침을 제안한다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.4
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• pp.85-94
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• 2004

Object tracking in a real time image is one of interesting subjects in computer vision and many Practical application fields during the past couple of years. But sometimes existing systems cannot find all objects by recognizing background noise as object. This paper proposes a method of object detection and tracking using adaptive background image in real time. To detect object which is not influenced by illumination and to remove noise in background image, this system generates adaptive background image by real time background image updating. This system detects object using the difference between background image and input image from camera. After setting up Minimum Bounding Rectangle(MBR) using the internal point of detected object, the system tracks object through this MBR In addition, this paper evaluates the test result about performance of proposed method as compared with existing tracking algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1429-1436
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• 2011

In this paper, a new tube-radius-measuring algorithm has been proposed for effectively measuring the radii of small tubes under severe noise conditions that can also perform well when metal scraps that make it difficult to measure the radius correctly are inside the tube hole. In the algorithm, we adopt a fuzzy searching method that searches for the center of the inner circle by using fuzzy parameters for distance and orientation from the initial search point. The proposed algorithm has been implemented and tested on both synthetic and real-world tube images, and the performance is compared to existing circle-detection algorithms, such as the Hough transform and RANSAC methods, to prove the accuracy and effectiveness of the algorithm. From this comparison, it is concluded that the proposed algorithm has excellent performance in terms of measurement accuracy and computation time.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.517-523
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• 2012

Biometrics is a study of identifying individual by using the features of human body. It has been studied for an alternative or complementary method for the classical method based on password, ID card, etc. In comparison with the fingerprint, iris, ear, palmprint, finger-knuckle print has been recently studied. This paper proposes an effective method for recognizing finger-knuckle print based on the feature of Gradient orientation. The main features of finger-knuckle print are the size and direction of winkles. In order to extract these features stably, we make a feature vector consisted of Gradient orientations after the preprocessing of enhancing non-uniform brightness and low contrast. Total 790 images acquired from 158 persons have been used at the experiment for evaluating the performance of the proposed method. The experimental results show the recognition rate of 99.69% and the relatively high decidability index of 1.882. These results demonstrate that the proposed method is effective in recognizing finger-knuckle print.

• Transactions of the KSME C: Technology and Education
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• v.2 no.1
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• pp.57-63
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• 2014

In this paper new air-cooling system utilizing Stirling engine was proposed for improving efficiency in solar photovoltaic power generation. The solar cell plate was equipped with semi-circular channel for air flow on the backside. Beta-type Stirling engine was installed on the plate and its flywheel was connected to a motor fan by a transmission belt. A forced convective air flow for heat radiation was generated by the operation of the self-starting Stirling engine. The performance tests for power generation of solar cell with or without the proposed air-cooling system were conducted under halogen lamp. From the experimental results, it was found that decline in output voltage of the solar cell with proposed cooling system was 25% less than that of the solar cell without cooling system.