• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.9-11
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• 2002

본 논문에서는 고속 회전기의 자기 베어링을 위한 새로운 파인 앰프(Power Amplifier) 구성 방법에 대하여 논하고자 한다. 그리고 이를 위한 새로운 PWM 구현 방법을 제안한다. 제안된 방법은 6개의 IGBT로 구성된 3개의 암(Arm)을 내장한 파워 모듈(Power Module)을 이용한다. 제안된 방법을 통해 필요한 파워 모듈의 숫자를 줄이면서도 자기 베어링 코일에 효과적으로 전압을 인가할 수 있음을 보인다. 또한 자기 베어링 1자유도 모의 실험 장치를 구성하여 제안된 방법의 실효성을 검증한다.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.15-17
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• 2002

자기 베어링을 구동하는 코일은 회전축의 위치 정보를 가지고 있다 따라서 코일의 인덕턴스를 알 수 있으면 위치 센서를 쓰지 않고도 회전축의 위치를 알아낼 수 있다. 본 논문에서는 코일에 고주파 신호를 주입하여 인덕턴스를 알아내고, 이를 통해 회전축의 위치를 추정하는 방법을 제안하고. 실험을 통해 이를 검증한다.

• The Journal of Korean Physical Therapy
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• v.31 no.6
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• pp.346-350
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• 2019

Purpose: The purpose of this study was to investigate the effects of calf tightness on gait, plantar pressure, and balance in adults. Methods: A total of 60 participants were divided into a normal group of 30 subjects with normal dorsiflexion angle (20-25 degrees) and an experimental group of 30 subjects with limited dorsiflexion angle (0-15 degrees) due to calf tightness. Gait ability and foot pressure of the subjects was measured with a treadmill, and the balance ability was measured by PROKIN system. Results: A significant difference in COP length, loading response, and single limb support was observed between groups. The COP length and single limb support ratio in the normal group was greater than in the experimental group, but the experimental group showed a higher ratio for loading response in the gait ratio. Conclusion: Our results indicated that calf tightness was negative effects on balance and gait ability, so assessment of the muscle tightness should be considered during exercise and treatment.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.11a
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• pp.69-72
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• 2000

색채 자극은 인간의 감성에 영향을 주며 또한 색채의 생리적인 작용을 응용하는 연구들이 보고되고 있다. 본 연구의 목적은 색채 자극이 정상인의 생리신호에 어떠한 영향을 미치는가를 정량적으로 측정해 보고자 하였다. 피검자는 정상인 성인 남,여 각 50명을 실시하였다. 색채 환경의 제시는 암실에서 백색광원에 채색 필터를 사용하여 제시하였다. EEG는 푸른색과 녹색에서 알파파가 상승하였으며, 베타파는 상대적으로 감소하였다. 심전도의 HRV분석에서는 남자는 녹색에서 부교감 신경계가 가장 활성화 되었으며, 여자는 파랑색에서 부교감신경계가 활성화 된 걸 볼 수 있었다. COP 측정에서는 녹색에서 누적거리가 가장 적은 것으로 나타났으나 통계적 유의성은 나타나지 않았다. 본 실험을 통해 색채 환경이 생리적 신호에 영향을 미치는 것을 알 수 있었으며, 임상적 응용을 위해서는 더 많은 피검자와 인지기능에 장애가 있는 환자를 대상으로 계속적인 연구가 필요한 것으로 사료된다.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.405-408
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• 2009

공기열원 히트펌프시스템의 문제점, 즉 열효율, 안정성, 착상에 대한 현황을 파악하고 이를 해결하기 위한 연구를 수행하였다. 열효율과 안정성을 위해 기존 시스템을 보완한 8행정 냉매사이클시스템 개발과 제어시스템의 개발을 통해 히트펌프 시스템의 효율을 2배 정도 증가시키고, 안정성을 높이며, 착상 문제를 최소화할 수 있도록 하였다. 개발된 공기열원 히트펌프시스템의 COP는 평균 5정도이고, 안정적으로 운용되는 외부 온도는 $-10^{\circ}C$에서 $55^{\circ}C$까지이다. 토출되는 온수의 온도는 $50{\sim}60^{\circ}C$정도이다. 평균 제상시간은 1분 이내이다. 앞으로 개발해야 할 문제는 외부 온도 $-10^{\circ}C$ 이하지역에서 보조열원 없이 난방을 할 수 있고 친환경 냉매를 사용하며 COP가 7이상인 고효율 히트펌프시스템를 실용화하는 것이다.

• Journal of Biomedical Engineering Research
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• v.21 no.2
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• pp.213-218
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• 2000

Pressure distributions of the soft tissue are valuable for understanding and diagnosing the disease characteristics due to the mechanical loading. Our system measures dynamic pressure distributions in real-time under the general PC environment, and analyzes various foot disorders. Main features of the developed system are as follows: (1) With the resistive pressure sensor matrix of 40${\times}$40 cells, the data is sent to the PC with the maximum sampling rate of 40 frames/sec. (2) For each frame, contact area, pressure and force are analyzed by graphic forms. Thus, various biomechanical parameters are easily determined at specific areas of interests. (3) A certain stance phase can be chosen for the analysis from the continuous walking, and the detailed biomechanical analysis can be done according to an arbitrary line dividing anterior/posterior or medial/lateral plantar areas. (4) The center of pressure (COP) is calculated and traced from the pressure distribution data, and thus the movement of the COP is monitored in detail. A few experiments revealed that our system successfully measured the dynamic plantar distribution during normal walking.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.2
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• pp.7-12
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• 2016

This study have an objective to suggest basic data and measured result of heating performance on water-water type horizontal geothermal heat pump which is based on heating and cooling load calculation result of small residential house. The average temperature during measured periods is $9.4^{\circ}C$ on primary EWT and is $7.6^{\circ}C$ on primary LWT. The temperature difference shows $1.8^{\circ}C$ as average temperature. Because the average outdoor temperature of peak is lager than on December and than on January, the temperature difference between EWT and LWT is bigger that on January than that on December. The system COP is 3.62.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.116-119
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• 2004

According to industrial development, all fields using chemical instrument and material are generated an electrostatics. This paper is represented the electrostatics distribution analysis of industrial type Inkjet plotter. In order to such experiment, an electrostatics for each portions of plotter(OJ-62) are measured by electrostatic measurement. Based on these, the big large position of electrostatics was analyzed by finite element method(Maxwell-2D), Here it is showed an electrostatic inducement and electric charge theory required.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.5
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• pp.411-421
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• 2001

The purpose of this study is to investigate the performance of an autocascade refrigeration system by simulation and experiment using refrigerant mixtures of R744/134a and R744/290 as working fluid. Variations of mass flow rate of refrigerant, compressor work refrigeration capacity and COP with respect to mass fraction of R744/134a and R744/290 mixture were presented under different operating conditions. Performance test has been executed by ASRAE standard. Experimental results show as the composition of R744 in the refrigerant mixture increases, heating and coling capacity are enhanced, but COP trends to decrease. Experimental results are compared with those from the simulation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.73-81
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• 1997

In this experimental study, the air cooling radial shape heat exchanger which influences on the COP and the cooling capacity by heat and mass transfer rate in the adsorbent bed was designed and applied to test its performance for adsorption heat pump(AHP). Zeolite-water was used for the adsorbent-adsorbat pair. As a result, the cooling COP and a cycle period of this adsorption heat pump are 0.28 and 2 hours, respectively, on the condition of none heat recovery from the adsorption reactor(absorber). The other results and recommendations are mainly related to improving the heat and mass transfer inside the absorber to reduce a cycle period.