• International Journal of Automotive Technology
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• 제6권6호
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• pp.625-633
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• 2005

Vehicle drift was reduced using statistical six sigma tools. The study was performed through four steps: M (measure), A (analyze), I (improve), and C (control). Step M measured the main factors which were derived from a fishbone diagram. The measurement system capabilities were analyzed and improved before measurement. Step A analyzed critical problems by examining the process capability and control chart derived from the measured values. Step I analyzed the influence of the main factors on vehicle drift using DOE (design of experiment) to derive the CTQ (critical to quality). The tire conicity and toe angle difference proved to be CTQ. This information enabled the manufacturing process related with the CTQ to be improved. The respective toe angle tolerance for the adjustment process was obtained using the Monte Carlo simulation. Step C verified and controlled the improved results through hypothesis testing and Monte Carlo simulation.

• 한국항해항만학회지
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• 제26권2호
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• pp.221-226
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• 2002

표류지점 추정 모델의 환경 입력자료를 확보하기 위해 부산항 연근해에서 표류실험을 실시하였다. 실험에는 크기가 다른 4척의 선박(10, 20, 50, 90톤급)이 사용되었다. 그중 50톤급 선박에는 해류, 바람, 위치를 자동적으로 기록하는 계기들을 장착하였고, 나머지 선박들에서는 분산각 추정 연구를 위해 위치자료만 기록하였다. 각 선박들의 위치는 DGPS와 자동위치발신기(APRS)를 사용하여 기록하였다. 실험은 풍속 2~10m/s, 유속 0.5~1.5m/s의 환경에서 행하여졌으며, leeway는 선박 표류속도에서 표층의 유속성분을 제거하여 구하였다. 50톤급 선박의 leeway rate는 풍속의 약 3.6%인 것으로 분석되었으며, leeway 방정식은 $U_L$ =0.042W -0.034로 표현되었고 leeway angle은 $-30^{\circ}$~$40^{\circ}$의 범위였다.

• 수산해양기술연구
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• 제45권3호
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• pp.144-150
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• 2009

The choice behavior of the octopus in response to the environment-friendly colored sinker for octopus driftline and the sinker's fishing effect were studied under experimental conditions in the water tank and the field. The colors of the sinkers used for the experiment are white, black, yellow and green. Artificial baits are attached to the sinkers in order to attract the octopuses in the experiment. In the water tank experiment, two sinkers of two different colors are placed in a compartmentalized corner of the rectangular tank, and a CCD camera records the choice behaviors of the octopuses to the colored sinkers. In the field experiment, the catch investigation of octopus for each colored sinker was conducted 14 times in total by using 2(A, B) commercial fishing boats at the coast of Gangneung within 30m of depth in 2006. The number of colored sinkers per operation was a total of 24-40 pieces with the same number of sinkers individually for four colors. As a result, it was found that the octopus selected white the most followed by black and yellow in their choice of colored sinkers in the water tank experiment, and green was the lowest in their choice. Even in the field experiment, the sinkers of white and black showed a higher catch of octopus than the sinkers of yellow and green.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.250-254
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• 2007

As photovoltaic(PV) power generation systems become more common, it will be necessary to investigate islanding detection method for PV systems. Islanding of PV systems can cause a variety of problems and must be prevented. However, if the real and reactive powers of the load and PV system are closely matched, islanding detection by passive methods becomes difficult. Also, most active methods lose effectiveness when there are several PV systems feeding the same island. The active frequency drift positive feedback method(AFDPF) enables islanding detection by forcing the frequency of the voltage in the island to drift up or down. In this paper the research for the minimum value of chopping fraction gain applied digital phase-locked-loop (DPLL) to AFDPF considering output power quality and islanding prevention performance are performed by simulation and experiment according to IEEE Std 929-2000 islanding test.

• Geosystem Engineering
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• 제21권5호
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• pp.282-290
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• 2018

The onset of extreme fire behaviour in a mine drift with longitudinal ventilation was analysed. A fire in a mine drift with continuous fuel load, involving several separate fires may lead to flames tilted horizontally and filling up the entire cross section. This will lead to earlier ignition, higher fire growth rate, higher fire spread rate and a severe fire behaviour. The focus has been on what changes take place at the onset and signs of the impending phenomenon. It was found that the fire gas temperature at the ceiling level provided a poor indicator. At the downstream far-field region of the fire, the sudden temperature increase at the lowest levels of the cross section and the sudden increase in flow velocities would provide signs of extreme fire behaviour. The corresponding full-scale heat release rates of the experiments at the onset of extreme fire behaviour were found to be very high for mining applications but not necessarily for tunnel fires. The heat release rate threshold for a mine drift with smaller cross-sectional dimensions would decrease considerably, increasing the likelihood of occurrence. The distance between the fuel items will play an important role during the initiation of horizontal flames.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.421-426
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• 2006

To examine the behaviors of traditional wooden structural frame in Korea in direction of beam, an experimental study was performed. The interior frame of Daewoongjeon of Bongjeongsa was selected as a model, which has two short exterior columns and one high inside column. The experimental frame has 1/2 scale and lateral forces are applied at high inside column by using drift control. The vertical gravity loads are applied on the frame. From the results of experiment it was shown that the stiffness and lateral capacity of the frame was increased when vertical loads are applied and the force-drift relationship in positive load direction was not same as in negative load direction. And push-over analysis are performed by using macro model in which the rotational and shear springs which were derived from the another experiments of subassemblies were used. The numerical analysis with macro model showed a good correspondence with the experiment within 2% story drift.

• 해양환경안전학회지
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• 제3권1호
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• pp.85-92
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• 1997

To understand the dynamics of a drifting object, an analysis based on fluid dynamics theory is presented. A simplified analysis shows a consistency with the linear formula currently used for search and rescue mission. Also an experiment using miniatured human models has been conducted to study the drift characteristics of Person-in-Water. The tests were carried out at the water channel facility and the models were tested in different positions and styles. The measured drag coefficients for human body ranged over 0.4-1.2.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.375-379
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• 1997

Thermal drift of the machine tool spindle due to temperature increase dominates the major source of the machine tool error. To compensate the thermal errors, software based error correction methods could be implemented. In th~s case, we need model to map the relationship between temperature and thermal distortion. Traditionally, two or three different methods have been trled: step increase of spindle speed, constant, random. The latter two methods are described in the document of ISOlDIS230-3. In this research, three different methods were verified through the experiments from the viewpoint of compensation of thermal distortion. Constant spindle speed turned out good enough for monitoring the behavior of the thermal drift and modeling the relationship between temperature and thermal distortion.

• 전력전자학회논문지
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• 제3권2호
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• pp.125-130
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• 1998

본 논문에서는 유도전동기 자속기준제어에 필요한 회전자 자속각 연산을 위한 새로운 자속 연산기를 제시한다. 순수 적분기로 구성된 자속연산기를 사용하여 전압, 전류 정보로부터 실제 회전자 자속을 추정하였다. 제안된 자속 연산기에서는 순수 적분기의 드리프트(drift) 문제를 해결하기 위한 새로운 보상 방법을 도입하였으며, 전동기 속도는 추정된 자속각과 추정된 슬립 주파수로부터 연산하였다. 제안된 방법의 성능을 실험을 통하여 입증하였다. 제안된 시스템의 정경속도의 1/100 이하에서도 안정되게 운전되는 것을 실험결과로부터 확인하였다.

• 전력전자학회논문지
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• 제16권2호
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• pp.145-151
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• 2011

본 논문은 신 재생에너지원 중 태양광을 이용한 계통연계형 PV PCS의 단독운전 검출 성능을 극대화하고, 출력 전력의 품질 악화를 최소화 할 수 있는 개선된 능동 주파수 변이기법의 외란의 크기를 모델링, 시뮬레이션 및 실험을 통하여 검증하고, 이를 근거로 계통 보호 협조 및 안전을 위한 개선된 능동적 주파수 변이기법의 타당성을 검증하고자 한다.