• 전기학회논문지
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• 제56권8호
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• pp.1367-1372
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• 2007

The modem large electric power system has made power system analysis much more complex and difficult. For effective analysis of the power system, model reduction and aggregation is required. In this paper, a new relation index to identify the coherency among the generators is presented and also a new aggregation method is presented to aggregate the coherent generators in the large scale power system while matching the power flow. In order to demonstrate the effects of this aggregation method, it is applied to the IEEE 39 bus test power system and to the 2006 summer power system of Korea Electric Power Corporation, and the simulation results are compared with those of the original system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.128-130
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• 2004

The cost losing synchronous through a transient instability is extremely high in modem power systems. This paper presents a power transfer capability calculation algorithm considering transient stability. The theoretical development is straightforward: dynamic equations are converted to numerically equivalent algebraic equation and then integrated into the standard formulation for power transfer capability calculation. The proposed method is applied to IEEE-24 Reliability Test System and the results shows the effectiveness of the method.

• Tribology and Lubricants
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• 제13권3호
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• pp.48-55
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• 1997

The ball bearing with thin-section raceways which is much lighter than other conventional bearings used in most modem passenger cars and small tracks. The important design parameters of this bearing is the groove radius of raceways, the diametral clearance, the free contact angle and so on. The optimal value of these parameters were determined by considering the dynamic load capacity, the contact angle and the calculated fatigue life. The contact angle between a ball and raceways was calculated by considering the local contact deformation and the structural deformation of thin-section raceways which was estimated by FEM. The raceways were made by means of the press-forming process. The fatigue life tester was designed and manufactured. The fatigue life test was executed and the reliability of this bearing was confirmed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1175-1178
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• 2004

On-line partial discharge(PD) monitoring system has been developed to monitor in operating large motor stator insulations. This system makes use of remote diagnosis techniques for the evaluation of PD activity in the control center of thermal power plant. This system can be remotely accessed via a modem to build database, analyze status and interpret the pattern of PD activity. A personnel computer is generally connected to ten motors to continuous measurement of the PD activity. The test data can be easily interpreted by a maintenance staff. For assessing the condition of stator winding in motors, this system ensures a reliable measurement and accurate estimation. Capacitive couplers used for on-line PD measurement have been 80pF. The maximum PD magnitude(Qmax), PD pattern and normalized quantity number(NQN) were performed by this system.

• International Journal of Automotive Technology
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• 제2권4호
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• pp.135-145
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• 2001

DEUTZ AG, co-founded in 1864 by Nicolaus August Otto, the inventor of the four-stroke cycle engine, has developed the new 2013 engine for commercial vehicles on the basis of the tried and tested 1012 and 1013 series. With 4 and 6 cylinder models, the engine covers the power range between 100 and 190 kW. At the time of their introduction to the market, the engines will meet the exhaust emission legislation of EURO IV and incorporate the potential for EURO IV, Further engineering targets were. (Compactness, Favourable power/cost relation, Low weight, Low fuel consumption and Low noise level). All targets could be accomplished in a relatively short development period via the application of modem simulation tools and test methods. In this paper, the design configuration of the engines is described with particular emphasis on measures for noise emission reduction and the combustion system including injection and turbo charging. Furthermore, we demonstrate the engine's potential to fullfill the European emission legislation EU4, which comes into force in 2005.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.591-594
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• 2002

This paper presents a systematic method of probing channel characteristics and communication reliabilities of home power line communication network applied to the Internet accessed control of home appliances. The effects of the three performance deteriorating factors, i.e., additive noise, channel attenuation, and intersymbol interference, can be systematically measured by applying the channel probing waveform in the frequency range from 100㎑ to 450㎑. Probability of bit error is derived with the probed channel parameters of the signal attenuation, noise and signal-to-interference ratio read in the frequency domain. The agreement between the derived probability of bit ewer and the measured probability of bit error support the validity of the proposed approach of probing home power line channel characteristics. The experimental results performed with the constructed test-bed applying the Proposed channel probing method and the operation reliability measurement of the overall networked system also support the feasibility of commercially deploying the PLC modem installed home appliances and their services for the Internet accessed home automation in densely populated residential apartment complexes.

• 복식
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• 제52권5호
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• pp.15-30
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• 2002

The purposes of this study were to identify the Chinese university students' clothing attitudes and purchasing behavior according to their lifestyle. Questionnaires developed by researcher were distributed and collected from 540 Chinese university students from Mar. 5 to Mar. 20, 2001. Means, frequencies, and percentages were calculated. Factor analysis, cluster analysis. one-way ANOVA, and Chi-square test were used for data analysis. And Duncan's multiple range test was followed. The factors of lifestyle were consumption, self-confidence, economy, accomplishment. sociability. fashionability, individuality, and conservation. Chinese university students were segmented into 4 groups of the modern sociable, the passive stagnated, the positive progresive, and the traditional conservative. The group size of the modem sociable was the smallest, and the traditional conservative was the largest. Chinese university students considered sexual attractiveness of clothing most important. Psychological dependence and ostentation of clothing were next important in a decending order. The passive stagnated considered conformity of clothing most important and showed the opposite tendency of the modern socialable. The positive progressive considered all aspects of clothing attitudes important, and showed the opposite tendency of the traditional conservative. Chinese university students utilized direct fashion information sources, and patronized medium or small size department store or traditional market.

• 한국멀티미디어학회논문지
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• 제12권9호
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• pp.1351-1362
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• 2009

현대전에서 상호운용성의 중요성이 계속해서 증가함에 따라 한국군의 국방부에서는 상호운용성 시험 평가 도구인 SITES(Systems Interoperability Test & Evaluation System)를 개발하여 정보체계의 상호운용성 수준 평가에 활용하고 있다. SITES는 정보체계의 상호운용성 시험 평가를 목적으로 하므로, 무기체계에 적용에는 한계가 있다. 이 논문에서는 무기체계 간 상호운용성 시험을 위한 상호운용성 시험 아키텍처, 상호운용성 시험 구성 요소들을 제안한다. 또한 제안한 아키텍처 및 시험 지원 도구들의 유용성을 입증하기 위해 프로토타입을 개발하였다.

• 한국멀티미디어학회논문지
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• 제18권6호
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• pp.742-752
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• 2015

The communications through the power lines are called as the PLC and this is a common name for the communication modes for the information delivery. This technology transmits the data through the power lines on which the information is stored with the form of high frequency signal. The characteristic of the frequency signal is that the signal can be separated from the power line through exclusive power line modem and transmitted to the terminal devices. In this paper, 'In-home Headcount' checking algorithm using Wi-Fi and taking above mentioned advantages is proposed, and the basic Technology for such Solitary Senior Citizen's Lonely Death monitoring system has been designed and implemented. The comparative analysis has been conducted in this paper with the test-operated and test bed-completed 'Hyosimi 119 Safety-Welfare System' which is still being tested since 2008. With the 'In-home Headcount Checking Algorithm', Wi-Fi connection/disconnection status and SSIDs of relevant Wi-Fis will be checked. We expect that our proposed method will become as the basic Technology which can prevent lonely deaths of elderly people living alone. Since the PLC technology can be normally implement all the functions used on internet anticipate that the technology could be applied to many areas to construct a new form of communication network.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.989-996
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• 2008

Recently, a few types of fish-cage in open sea are researched. This fish-cage has to operate monitoring system for keeping an optimum living condition for fish. The most efficient monitoring system is WVMS(Wireless Vision Monitoring System) for fish-cage in open sea. WVMS should be able to transmit video signal and communicate with each controller. So. it needs to be based on WLAN(Wireless LAN) which has characteristic of higher transfer-rate, In this paper, we propose a structure of WVMS using WLAN equipments for maritime environment and prove its effectiveness. We present the propagation loss model of WVMS's communication channel. measured by field test, and discuss its validity compared with the predictive value based on the Friss propagation model and Plane earth reflection model. We present the number of frames that is received from WLAN modem connecting with underwater-camera in field test spots. As a result, we confirmed that proposed WVMS is suitable for maritime environment and it is possible to be applied to fish-cage in open sea on 'seogwipo'.