• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1109-1114
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• 2005

The rolling contact fatigue of wheels for high speed trains is a matter of increasing importance. The wheel damages from fatigue crack makes noise up and safety down. RCF-casued accidents cause traffic congestion and economical costs as well as personal injuries. In this study, we examine the rolling contact fatigue of wheels for power car running at 300km/h. Using the results of multi-body dynamic analysis and the proposed procedure of Ekberg, we calculate the fatigue index of surface-initiated fatigue, subsurface-initiated fatigue and fatigue initiated at deep material defects. As a result. the fatigue index shows us whether fatigue will appear and in which form. In addition, we present Shakedown map on surface-initiated fatigue.

• ETRI Journal
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• v.35 no.4
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• pp.617-624
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• 2013

Low power consuming and highly responsive semiconductor-type microelectromechanical systems (MEMS) gas sensors are fabricated for real-time environmental monitoring applications. This subsystem is developed using a gas sensor module, a Bluetooth module, and a personal digital assistant (PDA) phone. The gas sensor module consists of a $NO_2$ or CO gas sensor and signal processing chips. The MEMS gas sensor is composed of a microheater, a sensing electrode, and sensing material. Metal oxide nanopowder is drop-coated onto a substrate using a microheater and integrated into the gas sensor module. The change in resistance of the metal oxide nanopowder from exposure to oxidizing or deoxidizing gases is utilized as the principle mechanism of this gas sensor operation. The variation detected in the gas sensor module is transferred to the PDA phone by way of the Bluetooth module.

• Journal of Communications and Networks
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• v.6 no.2
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• pp.163-172
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• 2004

Ultra Wide Bandwidth (UWB) spread-spectrum techniques will playa key role in short range wireless connectivity supporting high bit rates availability and low power consumption. UWB can be used in the design of wireless local and personal area networks providing advanced integrated multimedia services to nomadic users within hot-spot areas. Thus the assessment of the possible interference caused by UWB devices on already existing narrowband and wideband systems is fundamental to ensure nonconflicting coexistence and, therefore, to guarantee acceptance of UWB technology worldwide. In this paper, we study the coexistence issues between an indoor UWB-based system (hot-spot) and outdoor point to point (PP) links and Fixed Wireless Access (FWA) systems operating in the 3.5 - 5.0 GHz frequency range. We consider a realistic UWB master/slave system architecture and we show through computer simulation, that in all practical cases UWB system can coexist with PP and FWA without causing any dangerous interference.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.803-806
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• 2005

In this paper, we analyses of Architecture for High-speed authentication protocol in wireless communication. The rapid process in wireless communication systems, personal communications, and smartcard technologies has brought new opportunities and challenges to be met by engineers and researchers working on the security aspects of the new communication. In real world, we have restricted hardware environments with limited computational power and small memory, we meet more challenges. Then we analyes the need of consideration to implement the system.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1517-1518
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• 2006

This paper describes the design and fabrication of a partial discharge(PD) analyzer to evaluate insulation performance for low-voltage electrical and electronic devices. The analyzer consists of an adjustable AC power supply, a coupling network, an amplifier, a shielding encloser, a sample-hold (S/H) circuit and a data acquisition (DAQ) board. The analyzer holds the height of PD pulse for $10{\mu}s$ by the S/H circuit, and this makes possible to measure PD pulses having fast rise and short duration by a low speed analog-to-digital (A/D) converter. The data are transmitted to the personal computer through the DAQ board, and the designed analysis program calculate apparent charges, discharge inception and extinction voltages.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.242-244
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• 2003

The functional test of protection relays is divided into two kind of test types; the steady-state test and dynamic test. Because the steady-state test is comparatively easy, this test is used to test the characteristics of the relaying elements, operating values, resetting values and etc. using equipment such as Doble. But the dynamic test has to be performed on the test environment with RTDS(real time digital simulator) because of the dynamic characteristics of real protection relays. Therefore, it is not usually easy to perform dynamic test of relays using power system simulation tool based on PC(personal computer) such as PSCAD/EMTDC. This paper discusses how to develop and implement a test model and user-defined components that can be performed dynamic test using PSCAD/EMTDC.

• Korean Institute of Interior Design Journal
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• no.9
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• pp.10-17
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• 1996

With the ever-increasing important of high-speed information in society as we move towards the 21 st century. Interior design and it's working condition has been changed a great deal included a sort of each special character and make a difference against the others. It used to be find a great poles asunder of worker's safety and project quality according to the environmental dimension of interior construction field as if they should be a pleasantness or poor condition. This research aimed to improvement of environmental construction field of interior with construction engineers and particular interior labors in 4 phases as : ⅠThe preparatory phase : -Secure a Budget, Environmental safety supervisor -Fix of Design quality, Construction period. -Choice of Construction method, Sub constructing Ⅱ. Starting work phase ; -Capacity , Safety of temporary power line. -Carriage, Stock of Material -Safety of Electronic tools, -Personal protector. Ⅲ. Working period ; -Ventilation, I illumination of working place. -Measurement of environmental working condition Ⅳ.Finish working phase ; -Analysis of measurement data. -Evaluation and making up for the weak point. -Keeping data.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.150-154
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• 2008

통신기술과 컴퓨터기술의 발전으로 새로운 전기통신 서비스가 개발 보급되고, 그 예로 도난, 화재, 가스 유출 등 가정 안에서 일어나는 각종 위급상황을 해당관서에 자동으로 알려주는 원격 안전관리시스템의 중요성과 인력 검침에 따른 노동력 확보문제나 효율적이고 경제적인 검침에 따른 운용방안이 요구되는 시점에서 원격검침 시스템(AMRS)의 필요성이 더욱 대두되고 있다. 본 논문에서는 각각의 원격 검침 시스템의 사용된 통신 방식을 비교하고 원격 검침시스템의 국내 외 기술 개발 동향 및 앞으로의 발전방향을 모색하였다. 이에 고유가시대의 검침비용을 절감하고 고객 서비스 향상 방안에 도움이 되고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06b
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• pp.238-242
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• 2007

최근들어 휴대용 미디어 플레이어(Portable Media Player)와, 노트북 컴퓨터, PDA(Personal Data Assistant)의 사용이 늘어나면서 얼마나 오랜 시간동안 휴대용 장치를 사용하는가에 대한 문제가 큰 이슈로 떠오르고 있다. 그에 대해 많은 연구가 이루어져 있으며, 현재도 활발히 연구가 진행되고 있다. 본 논문에서는 프로세스 상태, 배터리 상태 그리고 응용프로그램 종류로 이루어진 상황을 고려한 동적 전력관리 시스템에 대해서 제안하고 그에 따른 세부적인 모듈에 관한 설명과 실험 결과를 보여준다. 실험결과 제안한 시스템을 적용하지 않았을 경우와 비교하여 약 14%의 전력 손실 감소 효과를 볼 수 있었다.

• The Korean Journal of Emergency Medical Services
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• v.25 no.1
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• pp.37-48
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• 2021

Purpose: The purpose of this study was to identify the degree of resilience, traumatic events, secondary traumatic stress, and calling reported by firefighters and to identify the factors affecting the resilience of firefighters. Methods: Data were collected using structured questionnaires and 200 fire officials working in D city were enrolled as the subjects. Data were analyzed using SPSS 24.0, and the analyses included descriptive statistics, independent t-test, ANOVA, Scheffé test, Pearson correlation coefficient, and multiple linear regression. Results: The difference in resilience according to general characteristics showed significant differences in health status (F=4.33, p=.014) and job satisfaction (F=6.13, p=.003). The factors affecting resilience were identified as calling (β=.25, p<.001), and the explanatory power for resilience was 19.2%. Conclusion: It is necessary to increase calling in order to increase resilience. Therefore, we suggest that professional education and programs that consider personal characteristics are needed to strengthen the calling.