• 한국수소및신에너지학회논문집
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• 제20권1호
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• pp.38-44
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• 2009

Recently, the research focused on fuel cell hybrid vehicles (FCHVs) is becoming an attractive solution due to environmental pollution generated by fossil fuel vehicles. The proper energy control strategy will result in extending the fuel cell lifetime, increasing of energy efficiency and an improvement of vehicle performance. Battery state of charge (SoC) is an important quantity and the estimation of the SoC is also the basis of the energy control strategy for hybrid electric vehicles. Estimating the battery's SoC is complicated by the fact that the SoC depends on many factors such as temperature, battery capacitance and internal resistance. In this paper, battery charging time estimated by SoC is studied by using the speed response and current response. Hybrid system is consist of a fuel cell unit and a battery in series connection. For experiment, speed response of vehicle and current response of battery were determined under different state of charge. As the results, the optimal battery charging time can be estimated. Current response time was faster than RPM response time at low speed and vice versa at high speed.

• 전기학회논문지
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• 제62권12호
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• pp.1678-1687
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• 2013

This paper describes a prototype of 3-phase 3.3kV/220V 6kVA modular semiconductor transformer developed in the lab for feasibility study. The developed prototype is composed of three single-phase units coupled in Y-connection. Each single-phase unit with a rating of 1.9kV/127V 2kVA consists of a high-voltage high-frequency resonant AC-DC converter, a low-voltage hybrid-switching DC-DC converter, and a low-voltage hybrid-switching DC-AC converter. Also each single-phase unit has two DSP controllers to control converter operation and to acquire monitoring data. Monitoring system was developed based on LabView by using CAN communication link between the DSP controller and PC. Through various experimental analyses it was verified that the prototype operates with proper performance under normal and sag condition. The system efficiency can be improved by adopting optimal design and replacing the IGBT switch with the SiC MOSFET switch. The developed prototype confirms a possibility to build a commercial high-voltage high-power semiconductor transformer by increasing the number of series-connected converter modules in high-voltage side and improving the performance of switching element.

• 한국정보전자통신기술학회논문지
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• 제11권4호
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• pp.388-393
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• 2018

본 논문은 고효율 리플렉터 일체형 50W급 AC 직결형 엔진을 개발하여 SMPS 사용하지 않고 제품의 소형화 및 경량화를 구현하여 소비자가 편리하게 사용하고, AC Driver의 취약한 부분을 보완하기 위해 다단 바리스터 회로를 설계하여 전자 부품 수량 감소를 통한 원가절감 전해 콘덴서를 사용하지 않는 회로 구성으로 고신뢰성을 구현 하여 LED수명을 증대시켰다. 또한 AC 직결형 구동장치를 IC 반도체로 제작하여 리플렉터 일체형으로 AC 직결형 구동장치를 적용 하여 제작 그 수명을 LED의 온전한 수명을 모두 사용할 수 있는 장치와 발광 다이오드 조명 장치의 제어 회로에 하나 이상의 발광다이오드를 포함하는 여러 개의 발광 다이오드 채널이 직렬로 구성되는 광원을 정류 전압으로 구동하는 발광 다이오드 조명 장치의 제어회로를 제안하였다.

• Structural Engineering and Mechanics
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• 제61권4호
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• pp.527-538
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• 2017

The evaluation of the loss-of-support conditions of frictional beam-to-column connections using simplified numerical models describing the transverse response of a portal-like structure is presented in this paper considering the effects of the seismic-hazard disaggregation. Real earthquake time histories selected from European Strong-motion Database (ESD) are used to show the effects of the seismic-hazard disaggregation on the beam loss-of-support conditions. Seismic events are classified according to different values of magnitudes, epicentral distances and soil conditions (stiff or soft soil) highlighting the importance of considering the characteristics of the seismic input in the assessment of the loss-of-support conditions of frictional beam-to-column connections. A rigid and an elastic model of a frame of a precast industrial building (2-DoF portal-like model) are presented and adopted to find the minimum required friction coefficient to avoid sliding. Then, the mean value of the minimum required friction coefficient with an epicentral distance bin of 10 km is calculated and fitted with a linear function depending on the logarithm of the epicentral distance. A complete parametric analysis varying the horizontal and vertical period of vibration of the structure is performed. Results show that the loss-of-support condition is strongly influenced by magnitude, epicentral distance and soil conditions determining the frequency content of the earthquake time histories and the correlation between the maxima of the horizontal and vertical components. Moreover, as expected, dynamic characteristics of the structure have also a strong influence. Finally, the effect of the column nonlinear behavior (i.e. formation of plastic hinges at the base) is analyzed showing that the connection and the column are a series system where the maximum force is limited by the element having the minimum strength. Two different longitudinal reinforcement ratios are analyzed demonstrating that the column strength variation changes the system response.

• 노동경제논집
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• 제26권2호
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• pp.61-95
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• 2003

이 논문에서는 노동시장과의 관련하에서 일본의 직업교육훈련제도의 특징과 최근의 변화 양상 및 의의를 구명하였다. 분석 틀로서는 마스텐(D. Marsden)과 미야모토(宮本光晴)의 고용제도 모형을 이용하였다. '지적숙련논쟁'의 검토 등을 통해 고도성장기 및 오일쇼크기에 형성된 일본의 직업교육훈련제도의 본질적 특징이 '직업능력으로서의 숙련'이 제도화되지 않은 채 OJT 중신의 기업내 훈련을 통해 직능자격제도상의 내부 승진에 의해 어는 정도 높은 수준의 다기능공으로서 기능을 형성하는 데 있음을 지적하였다. 최근의 장기 불황하에서 이러한 내부노동시장은 커다란 도전을 받고 있는데 그 변화의 방향은 내부노동시장의 붕괴가 아니다. 확대되는 외부노동시장을 자격제도의 정비에 의해 직업별 노동시장으로 정비하고 그것에 의해 내부노동시장을 유지해 나가는 정책 방향인 것을 구체적인 정책분석을 통해 밝혔다.

• 한국항해항만학회지
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• 제26권1호
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• pp.50-54
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• 2002

선박은 박판으로 이루어진 상자형구조물이기 때문에 선박이 황천항해를 하게 되면 선체의 상갑판과 선저판에는 호깅이나 새깅이 반복적으로 일어나므로 선테판에는 인장력과 압축력이 반복적으로 작용하게 된다 이 중에서도 압축력이 작용하는 경우가 선박의 종강도상에 치명적인 결과를 가져올 수 있다. 따라서, 본 본문에서는 선체판중에서 종횡비가 1.4인 판을 대상으로 하여 탄소성유한요소해석을 통하여 압축하중을 계속적으로 증가시켜 좌굴과 함께 탄소성대변형거동을 밝힘과 동시에 2차좌굴과 탄소성거동과의 메카니즘을 규명하여 압축하중을 받는 선테판의 탄소성대변형거동을 규명하였다.

• 전력전자학회논문지
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• 제17권2호
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• pp.158-165
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• 2012

In this paper, the test bed using three-phase PWM converter connected with single phase inverter in series is set up to configure an active AC electric load. Since the two topologies, three-phase PWM converter and single-phase inverter, can be operated bidirectionally, the system not only re-generates surplus power to grid but also prevents power dissipation. However, the construction of system has a drawback. That is, ripple components two times of inverter operation frequency occur at DC-Link due to cascade connection, it can be cause of three phase unbalance Since the operational characteristic of the active AC electric load, the power frequency entered into the electric load can be varied, and the ripple of DC-Link is changed as well. In this paper, the three-phase PWM converter using a variable notch filter is proposed, and the reduction of three-phase current unbalance is presented. the validity of the proposed PWM converter using a variable notch filter is verified by the simulation and experimental results.

• Progress in Superconductivity
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• 제3권2호
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• pp.241-246
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• 2002

We have performed the current and voltage loading tests of resistive superconducting fault current limiters (SFCLS) based on $YBa_2$$Cu_3$$O_{7}$(YBCO) films with the diameter of 2 inch. The SFCL consists of meander-type YBCO stripes covered with 200 nm Au layer grown in situ for current shunt and heat dispersion at hot spots. The minimum quench current of an SFCL unit was about 25 Apeak. Seven SFCL units were connected in parallel fur the current load ing tests at power source of 100 $V_{rms}$ $/2,000A_{rms}$. This SFCL units had maximum limiting current of 170 Apeak during the fault instant and then successfully controlled the fault current below 100 Apeak within 1~2 msec after short circuit. Increased short current also reduced the quench completion time with little change of current limiting characterization. We connected six SFCL units in series fur the voltage loading tests at power source of $1,200 V_{rms}$/170 $A_{rms}$ at this time. The shunt resistors were inserted into each SFCL unit to eliminate power imbalance originated from serial connection of SFCL units. Each SFCL unit was quenched simultaneously during the fault condition. The current increased up to 40 $A_{peak}$ and decreased to 14 $A_{peak}$ after 3 cycles. Quench was completed within 1 msec after the fault. We confirmed operating characteristics of 140 kVA($120 A_{rms}$ $\times$ 1,200 $V_{rms}$) SFCL and presented the manufacturing possibility of 3.3 kV SFCL using 4 inch YBCO films.BCO films.lms.

• 시큐리티연구
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• 제3호
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• pp.83-116
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• 2000

Many concerns have been raised for importance of disaster management after 1990's numerous urban disasters in Korea. When the primary function of government is to protect lives and property of citizens, disaster management should be included in the mainstream of public administration and many hazard countermeasures should be carried out for that purpose. The principal purpose of this research is to establish ways and means needed to improve the disaster management system in Korea. This paper is split into five chapters. Chapter I is the introduction part. Chapter II introduces the reader to a disaster management theory, and deals with various disaster management systems of foreign countries such as the U.S.A. and Japan, Chapter III describes and characterizes the Korea's current disaster management system. The Korean disaster management system has been reestablished through the enactment of the Disaster Management Act of 1995 and the full revision of Natural Hazards Management Act of 1995 after series of catastrophic man-made disasters since 1993. Chapter IV is devoted to the establishment of an effective disaster management system in Korea. In this chapter, I discusses measures needed to improve the quality of CDMB(Central Disaster Management Bureau)'s service to the people. I strongly reemphasize the effectiveness of a comprehensive risk-based, all-hazard national emergency management system that addresses preparedness, mitigation, response, and recovery. To that end the Administration should develop legislation, new policies, and organizational plans to invigorate the agency with a refocussed mission. Chapter V is a conclusion. As the demand for citizens'welfare has been continuously increased in the localization, the importance of disaster management is emerging subject in the public sector. The disaster management carries out complicated affairs and manages diverse objects, the cooperation/connection system of the central-local government and citizens, and non-governmental organization should be established.

• 한국잠사곤충학회지
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• 제13권1호
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• pp.17-22
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• 1971

1968년부터 1970년까지 뽕나무위축병에 관하여 접목전염 및 곤충매개전염시험을 한바 결과를 요약하면 다음과 같다. 1. 병근에 건전수목을 절접하므로서 활착주수중 30%의 전염율을 나타냈다. 건전근에 병수목을 절접함에 있어서는 병수목을 월동전에 채취 저장하였다가 익춘 공시한 것은 활착주수중 14%가 전염되였는데 반하여 월동후에 채취한 병수목에 있어서는 전혀 발병되지 않았다. 건전대목에 병수목을 절접하여 불활착된 것 중 대아가 발조한 것은 전혀 발병되지 않았다. 2. 뽕나무위축병의 무병지대에서 채집한 마름무늬매 미충을 중증위축병주에서 7일, 14일, 21일 간식 각각흡즙시킨 성충을 무병실생묘에 방사접종한 결과 7일구는 전염되지 않았으며 14일구는 22％, 21일구는 61％ 전염율을 나타냈다. 흡즙시간과 접종시간은 길수록 전염율이 높았다.