• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.774-780
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• 2021

The auxiliary power unit (APU) of a rotorcraft starts the engine during operation/flying. The APU is composed of a gas turbine engine type. The starting principle of the component is that the electric start motor generates the power required for starting by rotating the shaft. In this study, quality improvement was performed by applying an over-running clutch (ORC) between the APU and the starter motor to secure the operability of the starter motor of the APU mounted on the rotorcraft. The starter motor has the main role of starting the APU, but during operation, it is rotated without load by the rotational force of the APU gear shaft, resulting in friction at the brush. This phenomenon causes abrasion of the brush of the starter motor. Consequently, when the APU operation time increases, the brush life decreases, and the operability of the APU is affected. In this study, an ORC that separates the interlocking between the start motor brush abrasion and the APU operation time was applied to improve the operability/durability of the APU starter motor. The effect was verified through a test, and the technical feasibility of the design change was analyzed.

• Journal of Korean Society of Transportation
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• v.24 no.1 s.87
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• pp.53-58
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• 2006

The purpose of this study was to test the safety of the heel rest which was made for reducing the automobile driver's muscle fatigue with automatic transmission. Sixty subjects participated in the test, including ten males and ten females in 30s, 40s, 50s, respectively. Simulator consisted of automobile cockpit, accelerator and brake pedal sensor, heel rest. and driving displays. 30 seconds were given to subjects to be accustomed to the simulator environment. They also had one pre-trial to use the brake pedal according to the experimental scenario. They were told to step on the brake pedal immediately as soon as the red light was on the display The reaction time representing the foot travel time between accelerator and brake pedal was measured with/without the heel rest. In results, there was no significant difference in reaction time between conditions with/without heel rest. The result indicated that the heel rest used in this study would be a safe accessory for drivers who need to reduce the fatigue of the muscle or joint during driving.

• Journal of the KSME
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• v.50 no.8
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• pp.51-53
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• 2010

이 글에서는 항공우주왕복선의 엔진설계 시 사용되었던 CFD(Computational Fluid Dynamics) 기술을 인공심장 개발에 어떻게 적용하여 심장보조장치(Ventricular Assist Device)를 만들었는지 소개하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.331-332
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• 2012

• ETRI Journal
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• v.8 no.2
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• pp.109-116
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• 1986

본고는 TDX-1 전전가 교환기의 운용 관리기능인 과금, 통계, MMC 및 데이터 처리기능과 이들을 보조하는 각종 입출력 장치인 TTY(CRT) terminal, disk unit, CT unit, MT unit 및 data link 제어기능에 대하여 기술하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.821-822
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.881-882
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• 2008

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.534-546
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• 2002

The electrical interfaces among the components comprising the auxiliary power systems and their electrical interface with other train-borne systems are described. As such, this standard treats the auxiliary power system compononents as black boxes and addresses only their interface requirements.

• The Journal of Korean Society for Radiation Therapy
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• v.12 no.1
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• pp.144-146
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• 2000

삼차원 입체조형치료는 정상조직의 장해를 최소화하고 종양부위에 집중적으로 조사할 수 있는 장점을 가지고 있어 임상 적용범위가 넓어지고 있다. 일반적으로 정상조직의 장해를 줄이기 위해 다양한 방사선 조사방향이 사용되며 특히 비 동일면상에서의 조사가 많이 이루어진다. 따라서 couch 회전이 동반되며 couch는 선형가속기의 다른 기계적 오차보다 많은 오차를 유발할 수 있는 잠재적인 위험을 안고 있다. 저자는 이러한 오차의 정도를 파악하고 이를 개선할 수 있는 방법에 대해 알아보고자 했다. couch 회전에 따른 Isocenter의 변화를 평가하기 위해 3대(Primus, Simens, USA/CL600c & 2100c, Varian, USA)의 선형가속기를 이용하였으며 이중 1대의 장비에는 couch 회전시 오차를 줄이기 위해 고안된 couch 고정장치를 장착하였다. 환자가 테이블에 부하를 주지 않은 상태에서 회전을 실시하여 Isocenter의 변화를 측정하고 환자가 테이블에 누워있는 상황을 재현하기 위해 human phantom을 위치시킨 후 동일한 회전검사를 실시하여 각각의 오차를 비교 분석하였다. 각 실험은 10회씩 반복 측정하여 평균치를 얻었으며 오차의 분석은 AAPM 권고안인 오차중심의 반경으로 표현했다. 3대의 선형가속기를 이용하여 얻은 결과 테이블에 부하를 주지 않은 상태의 회전오차는 평균 2mm, 3.2mm, 2mm로 측정되었으며 휴먼 phantom을 올려놓고 부하를 준 상태에서의 오차는 평균 2.1mm, 4mm, 2.1 mm이였다. 또한 고정장치를 이용한 상태에서의 평균오차는 1.9mm로 나타났다. 삼차원 입체조형치료 시 couch 회전에 따른 Isocenter 오차는 장비의 종류 및 작업자의 사용방법에 따라 다르게 나타났으며 테이블의 부하가 클수록 많은 오차를 보였다. 또한 couch 고정장치를 부착한 장비에서의 결과치 만이 AAPM에서 권고하는 오차의 한계에(${\le}2mm$) 들어감을 알 수 있었다. 따라서 정기적인 QA가 필수적이며 Couch Locking System과 같이 오차를 줄일 수 있는 보조장치의 부착이 많은 도움을 줄 것으로 생각된다. 아울러 이러한 오차를 보정할 수 있는 방법이 강구되어야 할 것으로 사료된다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.152-159
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• 2010

High power density and power conversion efficiency have been required in the power converters according to the rapid growth of industry. In this context, the next generation High Speed Train(HST) requires power converter which has high-efficiency, high-performance and high-density. In this paper, the new control technique for battery charger used for the next generation HST is proposed. The phase shift ZVZCS converter is classified according to a resonant circuit which is located in the primary or secondary side. In this paper, The PWM switching technique using all-pass filter is proposed to control ZVZCS converter which has resonant circuit in the secondary side. ATmega_128 micro controller based in all-pass filter in substitute for phase shift IC is presented to have digital control. To verify the proposed topology, the simulation and experiment are performed by using PSIM software and 1[kW] experimental set-up.