• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.828-831
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• 2005

In this paper we propose a method to detect human faces from color image using pupil-template matching. Face detection is done by three stages. (i)separating skin regions from non-skin regions; (ii)generating a face regions by application of the best-fit ellipse; (iii)detecting face by pupil-template. Detecting skin regions is based on a skin color model. we generate a gray scale image from original image by the skin model. The gray scale image is segmented to separated skin regions from non-skin regions. Face region is generated by application of the best-fit ellipse is computed on the base of moments. Generated face regions are matched by pupil-template. And we detection face.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.3
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• pp.103-118
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• 2002

To provide the privacy of transmitted message over network the use of cryptographic system is increasing gradually. Because the security and reliability of the cryptographic system is totally rely on the key, the key management is the most important part of the cryptographic system. Although there are a lot of security products providing encryption, the security of the key exchange protocols used in the product are not mostly proved yet. Therefore, we have to study properties and operation of key agreement protocols based on elliptic curve in ANSI X9.63. furthermore, we analyze the security of their protocols under passive and active attacker models and propose the most suitable application field taking the feature of the protocols into account.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.6
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• pp.1-8
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• 2005

In this paper, we propose a two-stage head tracking algorithm adequate for real-time active camera system having pan-tilt-zoom functions. In the color convergence stage, we first assume that the shape of a head is an ellipse and its model color histogram is acquired in advance. Then, the min-shift method is applied to roughly estimate a target position by examining the histogram similarity of the model and a candidate ellipse. To reflect the temporal change of object color and enhance the reliability of mean-shift based tracking, the target histogram obtained in the previous frame is considered to update the model histogram. In the updating process, to alleviate error-accumulation due to outliers in the target ellipse of the previous frame, the target histogram in the previous frame is obtained within an ellipse adaptively shrunken on the basis of the model histogram. In addition, to enhance tracking reliability further, we set the initial position closer to the true position by compensating the global motion, which is rapidly estimated on the basis of two 1-D projection datasets. In the subsequent stage, we refine the position and size of the ellipse obtained in the first stage by using shape information. Here, we define a robust shape-similarity function based on the gradient direction. Extensive experimental results proved that the proposed algorithm performs head hacking well, even when a person moves fast, the head size changes drastically, or the background has many clusters and distracting colors. Also, the propose algorithm can perform tracking with the processing speed of about 30 fps on a standard PC.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.73-83
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• 2018

There has been increasing interest from NIST and other companies in studying post-quantum cryptography in order to resist against quantum computers. Multivariate polynomial based, code based, lattice based, hash based digital signature, and isogeny based cryptosystems are one of the main categories in post quantum cryptography. Among these categories, isogeny based cryptosystem is known to have shortest key length. In this paper, we implemented Supersingular Isogeny Diffie-Hellman (SIDH) protocol efficiently on low-end mobile device. Considering the device's specification, we select supersingular curve on 523 bit prime field, and generate efficient isogeny computation tree. Our implementation of SIDH module is targeted for 32bit environment.

• Journal of the Korea Society of Computer and Information
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• v.28 no.10
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• pp.93-101
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• 2023

In this paper, as a result of analyzing the TMIS authentication protocol using ECC and biometric information proposed by Chen-Chen in 2023, there were security problems such as user impersonation attack, man-in-the-middle attack, and user anonymity. Therefore, this paper proposes an improved authentication protocol that provides user anonymity to solve these problems. As a result of analyzing the security of the protocol proposed in this paper, it was analyzed to be secure for various attacks such as offline password guessing attack, user impersonation attack, smart-card loss attack, insider attack, perfect forward attack. It has also been shown to provided user privacy by guaranteeing user anonymity and untraceability, which must be guaranteed in TMIS. In addition, there was no significant increase in computational complexity, so the efficiency of execution time was achieved. Therefore, the proposed protocol in this paper is a suitable user authentication protocol for TMIS.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.299-309
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• 1998

The national coordinate system is an essential component for a geographic/land information system, since it provides the spatial reference for expressing position information. The national mapping of Korea has been based on 3-different meridians on the Gauss-Schreiber projection in year 1910s, later this was changed to the Gauss-Kruger projection. Existing map coordinate systems maintaining the national land survey project on 1910s, have some structural shortcomings of unknown computational procedures and projection methods. In this paper, the problems of the map coordinates usage and of longitudes origin shift(10.405") and their solutions are investigated. Also, this study discusses the issues involved in choosing coordinate system for digital mapping and their applications as a basis for spatial data management. The foreign country's coordinate systems are reviewed and the elements to realize a new unified grid coordinate system is proposed. The Transverse Mercator projection with a central meridian of $127^\circ\;30'$, scale factor 0.9996, and GRS80 ellipsoid, is selected in Korean peninsula.sula.

• Journal of KIISE:Databases
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• v.28 no.4
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• pp.632-642
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• 2001

The nearest neighbor query is an important operation widely used in multimedia databases for finding the object that is most similar to a given object Most of techniques for processing nearest neighbor queries employ multidimensional indexes for effective indexing of objects. However, the performance of previous multidimensional indexes, which use N-dimensional rectangles or spheres for representing the capsule of the object cluster, deteriorates seriously as th number of dimensions gets higher, In this paper we first point out the fact that the simple representation of capsuler incurs performance degradation in processing nearest neighbor queries. For alleviating this problem,. we propose(1) adopting new axis systems appropriate to a given cluster (2) representing various shapes of capsules by combining rectangles and spheres, and (3) maintaining outliers separately, We also verify the superiority of our approach through performance evaluation by performing extensive experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.206-206
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• 2008

압전소자를 이용한 초음파 모터는 전자기적 원리로 동작하는 기존의 모터에 비해 구조가 간단하고 소형, 경량화가 가능하며 저속에서 큰 토크가 가능하고 ${\mu}m$단위 까지 정밀제어가 가능하다는 장점 등으로 인해 그 응용분야가 점차 확대되고 있다. 초음파 모터의 원리는 수평과 수직방향에서 변위가 타원형 운동을 형성하는 것이다. 따라서 선택한 타원운동의 방식에 의해서 모터의 형상이 달라진다. 초음파 모터는 액츄에이터를 사용하여 만들기 때문에 액츄에이터의 특성은 모터의 타원변위나 토크에 영향을 미친다. 단판형 액츄에이터에 비하여 적층 액츄에이터는 입력 임피던스를 낮추어 낮은 구동전압에서 구동이 가능하며 큰 변위와 토크를 발생하기 때문에 진동자의 수명 향상과 구동전압을 낮추기에 적합하다. 적층 액츄에이터는 변위량이나 응력 등을 개선하기 위해서 전기기계 결합계수(kp) 및 압전 d상수가 큰 재료가 요구되며, 고전압에서 장시간 구동 시 마찰에 의한 열손실을 감소시키기 위해 높은 기계적 품질계수(Qm)를 가져야한다. 적층 시 내부전극으로 사용하는 Pd, Pt가 함유된 전극은 가격이 비싸 제조비용을 상승시킨다. 상대적으로 값싼 Ag전극을 사용하면 비용절감을 할 수 있지만 융점이 낮아서 저온소결이 불가피하다. 따라서, 특성이 우수한 적층 액츄에이터를 제조하기 위해서 저손실, 저온소결 할 수 있는 액츄에이터 재료가 필요한 실정이다. L1-B4 혈 선혈 초음파 모터는 L1모드와 B4모드의 공진 주파수가 일치하여야 큰 변위를 얻을 수 있는데 이전의 논문에서 Atila를 이용한 시뮬레이션 결과를 분석한 봐 있다. 적층 액츄에이터의 층수를 5,7,9,11,13,15층으로 하여 L1-B4모드에서의 공진주파수를 비교한 결과 13 층일 때 두 모드가 비슷한 공진주파수를 보였고, 티원변위궤적도 다른 층수에 비해 크게 나타났다. 본 연구에서는 시뮬레이션 결과 가장 좋은 특성을 보인 13층 액츄에이터로 선형 초음파 모터를 제작하였다. 또한, 액츄에이터는 압전 및 유전특성이 우수한 저온소결 PZW-PMN-PZT세라믹을 이용하여 제작하였고, 내부전극으로 Ag전극을 사용하였다. 제작된 13 층 선형초음파모터를 가지고 프리로드 및 전압에 따른 속도를 조사하였고, 시뮬레이션 결과와 비교해 보았다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.3
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• pp.281-293
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• 2020

Recently, large and small fires have been happening more often in Korea. Fire is one of the most frequent disasters along with traffic accidents in korean cities, and this frequency is closely related to the land use and the type of facilities. Therefore, in this study, the significance of fires was analyzed by considering land use, facility types, human and social factors and using 10 years of fire data in Jinju city. Based on this, OLS (Ordinary Least Square) regression analysis, SLM (Spatial Lag Model) and SEM (Spatial Error Model) using space weights, were compared and analyzed considering the location of the fire and each factor, then a statistical model with high suitability was presented. As a result, LISA analysis of spatial distribution patterns of fires in Jinju city was conducted, and it was proved that the frequency of fires was high in the order as follow, central commercial area, industrial area and residential area. Multiple regression analysis was performed by integrating demographic, social, and physical variables. Therefore, the three models were compared and analyzed by applying spatial weighting to the derived factors. As a result of the significance test, the spatial error model was analyzed to be the most significant. The facilities that have the highest correlation with fire occurrence were second type neighborhood facilities, followed by detached house, first type neighborhood facilities, number of households, and sales facilities. The results of this study are expected to be used as significant data to identify factors and manage fire safety in urban areas. Also, through the analysis of the standard deviation ellipsoid, the distribution characteristics of each facility in the residential area, industrial area, and central commercial area among the use areas were analyzed. In, the second type neighborhood facility with the highest fire risk was concentrated in the center. The results of these studies are expected to be used as useful data for identifying factors and managing fire safety in urban areas.