• 한국정밀공학회지
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• 제28권4호
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• pp.526-533
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• 2011

This research is about the pulsatile pump system utilized in the perfusion bioreactor for the in vitro human tissue culture. A pulsatile pump system which can be applied to the culture of the vascular tissues including blood vessel is developed by using the idea of human heart's blood pumping into organs as followings: culture chamber, a pressurizing device which generates laminar pulsatile flow by controlling the x-sectional area of the culture media delivering tubing, a compliance chamber which supplies the pressuring device with a constant pressure, and a peristaltic pump which circulates the culture media in a circuit ranging from the culture chamber to the compliance chamber. The developed pulsatile pump system shows that a physiology of the human heart's blood pumping including pulsatile pressure waveform of systolic-diastolic pressure is well represented. Not only time domain but also frequency domain characteristics of pulsatile pump system which are necessary for the vascular tissue culture such as pulsatile pressure waveform's shape, the frequency, and the magnitude can be easily generated and manipulated by using the proposed system.

• 전자공학회논문지
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• 제51권10호
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• pp.204-209
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• 2014

본 논문은 맥파전달현상을 유지하며 맥압을 조절할 수 있는 시뮬레이터를 제작하는 것이 목적이다. 이를 위해 탄성튜브와 컴플라이언스 챔버를 융합하였다. 본 시뮬레이터는 슬라이더-크랭크로 구성된 압력발생부, 저항조절부를 포함한 혈관부, 수조 그리고 측정부로 구성되어있다. 챔버의 위치선정을 위해 챔버의 위치에 따른 맥파의 변화를 실험하였다. 또한 챔버가 맥압에 미치는 영향을 보기 위해 챔버의 유무에 따른 맥압의 변화를 비교하였다. 챔버의 유무가 맥파전달현상에 미치는 영향을 조사하였다. 실험결과, 튜브의 상류지점에 챔버를 설치할 때가 하류지점에 설치할 때 보다 인체와 더 유사한 압력파형을 나타냈다. 챔버를 설치하였을 때가 설치하지 않았을 때보다 인체와 유사한 맥압을 생성하였다. 챔버의 설치여부에 따른 맥파 전달 속도는 큰 변화가 없었다.

• 설비공학논문집
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• 제9권2호
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• pp.93-103
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• 1997

This study presents a way of improving the stability of fixed scroll in scroll compressors. For the scroll compressor whose fixed scroll is designed to move in the axial direction for the axial compliance, the fixed scroll is under the influence of the overturning moment produced by internal gas forces. Unless the overturning moment is properly compensated by the moments of reaction forces at the suspension of the fixed scroll to the compressor frame, the fixed scroll would exhibit wobbling motion, increasing gas leakage through the gap induced by the wobbling of the fixed scroll between the two scroll members. The conditions on which the wobbling motion can be suppressed have been found analytically; The axial position of the fixed scroll suspension should be made within a certain range. The upper limit of this range is the axial location for the o-rings which are inserted between the fixed scroll and the back pressure chamber to promote sealing for the gas in the back pressure chamber. And the lower limit is mainly determined by the magnitude of the axial sealing force. As long as the axial sealing force is not negative over all crank angles, the lower limit is not above the mid-height of the scroll wrap. Larger axial sealing force lower the lower limit.

• 한국지역사회생활과학회지
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• 제22권3호
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• pp.445-454
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• 2011

This study was performed on 5 prehypertensive male participants to investigate the effects of the clothing program for improving the vascular compliance on heat tolerance. The clothing program means the alternate stimulation of the temperature using clothes. The participants wore two different garments with $1.5^{\circ}C$ difference in the temperature inside clothing in a climatic chamber ($18.8{\pm}0.2^{\circ}C$, $38{\pm}3%RH$) alternately for 4 weeks. Heat tolerance tests were conducted in the climatic chamber of $35.2{\pm}0.5^{\circ}C$, $54{\pm}3%RH$ before and after the clothing program. The results were as follows. The $\overline{T}$sk, Tr and heart rate were lower in the post test than in the pre test (p<.01). The whole body and local sweat rates as well as systolic and diastolic blood pressures had reduced the tendencies in the post test. Participants felt less wet and more comfortable in the post test than in the pre test(p<.01). These results showed that the clothing program through the alternate stimulation of the temperature positively affected the improvement of heat tolerance.

• 대한의용생체공학회:의공학회지
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• 제19권4호
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• pp.385-391
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• 1998

이동형 작동기 방식의 완전이식형 인공심장을 대상으로 부가적인 체적보상실(compliance chamber)이 필요없는 새로운 균형적 심방압 유지방법을 개발하였다. 이동작동기으 lqleocld 원주운동을 통하여 좌우심박출의 균형을 유지할 수 있었으며, 두 시실 사이의 공간에 존재하는 공기가 심박출량 차이를 보상하도록 고안되었다. 인공심장 표면이 가변적인 부분은 좌우 심박출량의 균형 보상을 도와주게 된다. 그러나 인공심장 표면의 가변성을 높일 경우, 전체 심박출량의 감소를 유발할 수 있다. 본 논문에서는 두 심실사의 공기량을 조절하여 좌우 심박출량의 균형 및 전체 심박량에 대하여 좋은 조건을 모의 순환 실험을 통하여 결정하였다. 새로운 인공심장은 63kg의 양에 이식하여 3일간 생존하였으며, 생존기간중 평균심박출량은 4.21/min 이었으며, 심방압은 15mmHg 이하로 유지되었다.

• International Journal of Air-Conditioning and Refrigeration
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• 제17권1호
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• pp.1-6
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• 2009

The optimum design of back pressure chamber is one of the most important factors in designing scroll compressors because it has a great influence on the efficiency and other design parameters. The design process can be divided into 2 parts. One is obtaining the optimum pressure of the chamber and keeping it in constant value. The other is finding out the minimum inflow rate of medium with which back pressure chamber is filled. In this study we are focused on the first step. At first we added a simple structure that can change back pressure without reassembling compressor. It makes possible to obtaining optimum back pressure. Then we designed an equipment that the back pressure control valve assembly could be independently tested with. Spring was redesigned to decrease stiffness variation. Also sealing mechanism of back pressure control valve was improved to more effective way. As a result, it was verified that in a real mode test back pressure variation could be retained in 2.3% with discharge pressure and operating frequency varied. In addition the integrated structure of back pressure control valve is expected to contribute to effective manufacturing process.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.216-218
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• 1995

A new atrial pressures balancing method for moving actuator total artificial heart(TAH) without an extra compliance chamber is developed. The structural characteristics of the pendulous moving actuator have made it possible to compensate the left and right pump output difference by utilizing the interventricular air space as an internal compliance chamber in a pump housing. Furthermore, the balancing performance is increased through the improvement of the flexibility of part of the polyurathane housing. However, the increase of the flexibility of the housing causes a little loss of the cardiac output due to the reduction of active filling performance. In this paper, a good condition between the balance and pump output performance is evaluated by adjusting the air volume in the interventricular space through a series of in vitro experiment.

• 한국음향학회지
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• 제26권3호
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• pp.115-122
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• 2007

본 연구에서는 마이크로스피커의 구조와 특성을 유닛과 덕트형 인클로저로 구성되어 있는 일종의 덕트형 스피커시스템처럼 취급할 수 있음을 처음으로 보여주었다. 후면기공의 면적이 증가할수록 스티프니스는 감소하고 컴플라이언스는 증가하였다. 그 결과로써, 후면기공의 면적이 증가할수록 공명진동수가 컴플라이언스의 제곱근에 비례하여 증가하였다. 후면기공의 면적이 감소함에 의하여 중저음 영역에서의 기준음압레벨이 지수함수적으로 감소하였다.

• 대한의용생체공학회:의공학회지
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• 제41권1호
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• pp.8-13
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• 2020

To develop cardiovascular simulator capable of implementing pulse waves similar to the human body, accurate information about reflection wave is required. However, the conclusion is still not clear and various discussions are underway. In this study, the pulse wave velocity of the tube used in the experiment was first determined by measuring the pressure waves at two points in a single tube system with the experimental device to implement the pulse wave transmission of blood vessels, and the superposition time and characteristics of the reflection wave were confirmed. After that, an air chamber was set at the reflection site, and the effect of the change of air volume on the reflection wave was investigated. Finally, the effect of the number of branches connected to a single tube on the reflection wave was investigated. The superposition time of the reflection wave can be controlled by the air volume of the air chamber, and the magnitude of the reflection wave is influenced by the number of reflection sites that generate the reflection wave. The results of this study may be of practical assistance to simulator researchers who want to implement pulse wave similar to clinical data. It is expected that the more results similar to clinical are provided, the greater the scope of the simulator's contribution to clinical cardiovascular research.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권1호
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• pp.40-49
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• 2002

Floating fixed scroll adopted for tip sealing enhancement in a scroll compressor is always under the influence of tipping moment produced by internal gas forces. Unless the tipping moment is property compensated by some restoring moment, the fired scroll would suffer tipping movement, degrading the compressor performance. The condition on which the tipping movement of the fixed scroll can be suppressed has been investigated analytically. For no tipping movement, the floating fixed scroll should be suspended on the main frame at proper level. The upper limit of the stable suspension is the axial location of the o-rings adopted for a back pressure chamber sealing on the rear side of the fixed scroll, and the lower limit is the mid-height of the scroll wrap.