• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.677-677
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• 2013

최근 석유에너지의 고갈과 휴대용 전자기기의 사용의 증가로 고효율의 배터리의 개발이 요구되고 있다. 생체칩에서 부터 전기자동차, 에너지 저장체까지 광범위한 산업군에 걸처 배터리의 개발이 되고 있어 시장규모의 계속적인 성장이 있을 것으로 전망하고 있다. 현재 상용되고 있는 음극 재료는 카본재료(이론 용량 372 mAh/g)이다. 이 카본재료의 특징은 값이 싸고, 표준 환원전위가 낮아 비교적 높은 전압을 낼 수 있다. 그러나 낮은 에너지밀도를 갖으므로 높은 에너지를 필요로 하는 차세대 산업군인 전기자동차 등에는 적합하지 않은 것으로 평가되고 있다. 그래서 더 높은 에너지 밀도를 갖는 다른 재료들에 대한 연구들이 활발히 이루어지고 있다. 본 연구에서는 음극 재료로서 주석을 선택해서 연구를 하였다. 카본계열의 음극재료의 질량당 이론 에너지 밀도는 372 mAh/g임에 반해 주석같은 경우는 약 991 mAh/g 정도의 비교적 큰 이론용량을 갖고 있다. 하지만, 주석 등 금속, 혹은 금속 합금을 음극재료로 사용할 경우 많은 양의 리튬이 삽입/탈착되면서 약 300% 이상의 부피변화가 있게 된다. 그러한 과정에서 주석이 분쇄되어 떨어지거나 전자를 제공받는 집전체로부터 떨어지게 되고, 이 과정에서 심각한 에너지 밀도의 손실이 일어나게 된다. 이러한 문제점들을 극복하기 위해 다음과 같은 구조들을 고안하여 도금 공정을 사용하여 음극재료를 제작하여 실험을 진행하게 되었다. 도금법은 대면적을 싼 가격으로 할 수 있으며 원하는 두께 및 모폴로지까지 쉽게 조절할 수 있다. 부피팽창에 의한 스트레스를 최소화하기 위해 도금법을 사용하여 나노구조를 만들어 그에 따른 전기화학적 특성 변화를 측정하였다. 다공성 필름인 AAO 디스크의 한 면에 구리를 sputtering 공정을 사용하여 0.5 um 두께의 seed layer 구리 박막을 형성하고 형성된 구리 박막 위에 도금공정을 이용하여 두껍게 구리를 증착함으로 구리 음극 집전체를 형성한다. 그 후 AAO 구조 안에 주석을 도금하면 AAO의 구조를 따라 주석 나노와이어가 형성이 된다. 마지막으로 NaOH로 AAO를 제거해주면 직경 200 nm, 길이 2 um 정도의 주석 나노와이어를 구리 집전체위에 만들 수 있었다. 배터리의 용량을 측정한 결과 안정한 싸이클 특성과 약 400 mAh/g의 에너지 밀도를 갖는 것으로 나타났다.

• Convergence Security Journal
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• v.17 no.4
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• pp.3-9
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• 2017

Recently, Wireless communication has been widely used as a short distance communication medium in various industrial fields as well as communication connection between home appliances due to the appearance of the Internet of Things. And Most commonly used wireless communication media include WiFi, Bluetooth, and NFC. Among them, Bluetooth is widely used for communication between smart devices as well as computer peripheral devices. And Bluetooth in the home network fields is being used to control electronic products. However, since Bluetooth security vulnerabilities are known, more and more attacks are being exploited. As the application range of Bluetooth is expanding, it is necessary to prepare countermeasures accordingly. Therefore, this study investigates the security threat factors of through Bluetooth'attack case and attack technology. And By proposing countermeasures against this problem, we intend to utilize it as data for improving the security of wireless network service in the future.

• Journal of the Korea Society of Computer and Information
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• v.12 no.2 s.46
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• pp.161-170
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• 2007

This paper is a matter of remote control apparatus and display remote control system comprising the same. The remote controller is a wireless remote pointing device that is included a function of mouse and a function of remote controller for VOD etc. It is assembled a sending signal part to communicate with display device, a image sensor part to capture a scene of front view and a main body. Also, it includes a control part that analyzes the captured image, calculates a relative moving factor that main body is moved by user, and then controls the mouse cursor on the display device. The remote control apparatus is able to capture a seen of front view, to analyze the captured image, and to move a mouse cursor point on the display device as much as it calculated relative moving factor. Therefor it brings don the cost of production by a product desist that is increased user satisfaction. And it, using the patent and the new product desist, will make an epoch in development of the remote control system for Ubiquitous broadcasting industry.

• Journal of Digital Contents Society
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• v.16 no.1
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• pp.63-70
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• 2015

In this paper, we estimate the life cycle from acceleration life test about the hard disk of disk array of image storage of PACS. Webuil distribution was selected by the Anderson-Darling goodness-of-fit test with data of down time at $50^{\circ}C$ and $60^{\circ}C$. The equality test of shape parameter and scale parameter was conducted, so that the probability distribution estimated from data of down time at $50^{\circ}C$ and $60^{\circ}C$ was not statistically significant. The shape parameter was 1.0409, The characteristic life was 24603.5 hours at normal user condition($30^{\circ}C$) by the analysis of weibull-arrhenius modeling which included the acceleration factor of temperature, and The activation energy was 0.5011 eV through arrhenius modeling. The failure analysis of the failure samples of acceleration test and the samples of market return was conducted, so that the share percentage of failure mode was detail difference but the rank of share percentage was almost same. This study suggest the test procedure of acceleration test of hard disk drive in PACS using environment, and help the life estimation at manufacture and use.

• Convergence Security Journal
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• v.6 no.3
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• pp.117-126
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• 2006

Bayesian inference and model selection method for software reliability growth models are studied. Software reliability growth models are used in testing stages of software development to model the error content and time intervals between software failures. In this paper, could avoid multiple integration using Gibbs sampling, which is a kind of Markov Chain Monte Carlo method to compute the posterior distribution. Bayesian inference for general order statistics models in software reliability with diffuse prior information and model selection method are studied. For model determination and selection, explored goodness of fit (the error sum of squares), trend tests. The methodology developed in this paper is exemplified with a software reliability random data set introduced by of Weibull distribution(shape 2 & scale 5) of Minitab (version 14) statistical package.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.159-164
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• 2016

In or to generate high electric power in increasing demand, power station should operate facilities to meet requirement. The scale of electric power equipment is increasing in both size and complexity. With unexpected accidents at power facilities or power stations happening, substantial socioeconomic losses in an industrial society is caused. A major cause of unexpected accidents is deterioration of dielectrics, isolating two conductors electrically. In order to detect the deterioration processes of power cables, the operation status of power cables should be monitored on a regular basis. We have invented and installed equipment at Korea Western Power Co., Ltd., located in Taean, in order to predict and prevent the deterioration status of dielectrics destruction of power cables. The main line in Y-connection to the secondary coils of transformer delivers electric power to the external devices. The equipment we developed is the one measuring insulation resistance of cables operation in on/off status with respect to the main line. We present the equipment in terms of operation and configuration of hardware side.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.829-835
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• 2017

Recently, the health issues triggered by fine dust matters occurred in higher frequency. Having adverse effects on health, particulate matters affect the human body indoors as well as outdoors. There is thus a need for a system to measure the concentration of particulate matters and control harmful particulate matters for human health in the indoor spaces where people live. The present study applied Internet of Things(IoT) technologies in order to increase the efficiency of the conventional fine dust measurement system. Especially, for the bidirectional communication environment, directly construct a separate server and applied to the system instead of a free cloud server also we used it directly in the school lab and home. When the proposed system is used in schools and homes, it can recognize the indoor environment quickly and it is expected that this will gradually contribute to the health of the individual. Users can also check the server data outside and deal with the current indoor situations.

• Journal of the Korean Geographical Society
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• v.42 no.5
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• pp.675-690
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• 2007

It has been widely believed that the ethnic relations in Honolulu and Hawai'i in the early twentieth century were little associated with racist ideology because the white race was minority in terms of the racial composition. In reality, however, the racial and ethnic issues have played a major role in forming the past and present relations among ethnic groups. This study shows that the white-supremacy ideology exerted a strong influence on minority groups in Honolulu throughout the immigration and settling-down process, as much as in the mainland U.S. Clear occupational stratification and residential segregation among the ethnic groups in Honolulu represented almost the same situation as in mainland cities. The social segregation and spatial propinquity of their residential neighborhoods facilitated the construction of dichotomized identity: "Local" versus "Haole". Such transformed identities were a product of on-going inter-ethnic negotiation process embedded in the non-white multi-ethnic neighborhoods.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.447-458
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• 2012

The purpose of this paper is to introduce a design method to making characterized street for city regeneration and strategy for regional activation through making characterized street. For this purpose we analyze a case of 'Bosu-dong Book Street' in the city of Busan with compared to the cases of 'Hay on wye' in UK and 'Kanda old book street' in Japan. We have some suggestions from this analysis as follows; 1. Connection with tourism and publication industry is needed for regional economic vitality and urban regeneration. And Both of Softwares and Hardwares those are based on local identity are needed to be developed as contents of the street, 2. Merchants and Residents have to take the leading part and public authority is need to support them as street makers. 3. Sustainable participation and efforts of the community leaded by merchants and residents are needed in the whole process of making characterized street such as making, operating and management of hardware & software.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.7
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• pp.283-290
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• 2015

In this paper, we propose a hybrid method for the recognition of answer types in the WiseQA system. The answer types are classified into two categories: the lexical answer type (LAT) and the semantic answer type (SAT). This paper proposes two models for the LAT detection. One is a rule-based model using question focuses. The other is a machine learning model based on sequence labeling. We also propose two models for the SAT classification. They are a machine learning model based on multiclass classification and a filtering-rule model based on the lexical answer type. The performance of the LAT detection and the SAT classification shows F1-score of 82.47% and precision of 77.13%, respectively. Compared with IBM Watson for the performance of the LAT, the precision is 1.0% lower and the recall is 7.4% higher.