• Journal of Advanced Marine Engineering and Technology
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• 제40권7호
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• pp.563-568
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• 2016

본 연구는 연료전지 자동차용 공기조화기의 난방성능평가를 위하여 기존의 전반적인 히트펌프 시스템 중 공기열원 히트펌프 시스템의 증발기를 판형열교환기로 교체하여 시스템에 흐르는 냉매와 연료전지 스택 폐열을 직접 열교환이 가능한 수열원 이용이 가능한 난방시스템의 성능실험을 수행하였다. 실험결과에서 압축기의 회전수가 높을수록 소비동력이 증가하였다. 공기열원 이용방식의 경우 압축기 회전수가 1,200rpm이고 EEV개도가 25%인 경우 $COP_h$가 2.03으로 가장 높게 나타났고, 같은 압축기의 회전수에서 수열원 시스템은 EEV개도가 75% 및 스택 폐열의 온도가 $50^{\circ}C$인 경우 $COP_h$가 9.42로 가장 높게 나타났다.

• 한국산학기술학회논문지
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• 제12권10호
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• pp.4308-4313
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• 2011

본 연구에서는 친환경 대형 버스 차량에 적용되는 루프형 전동식 냉방시스템의 성능특성을 파악하기 위하여 스크롤 압축기의 주파수 및 승차 공간의 온도인 내기온도를 변화시켜가면서 다양한 실험을 진행하였다. 이를 위하여 인버터로 구동되는 전동식 스크롤 압축기를 적용한 냉방시스템을 설계 및 제작 하였고 냉매 충진량 실험을 통하여 루프형 전동식 냉방시스템의 충분한 과냉도를 확보할 수 있는 최적 냉매 봉입량을 선정하였다. 압축기 주파수가 55 Hz에서 65 Hz로 증가함에 따라 냉방시스템의 증발용량은 4.3% 증가하였으나 냉방 COP는 14.1% 감소하였고, 내기온도가 $27^{\circ}C$에서 $35^{\circ}C$로 증가함에 따라 냉방시스템의 증발용량 및 COP는 각각 9.17%와 1.43% 증가하였다. 더불어 전동식 스크롤 압축기를 구동하는 인버터의 작동 효율은 내기온도 변화보다는 압축기 주파수 변화에 더 큰 영향을 받는 것을 확인하였다.

• 한국산학기술학회논문지
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• 제14권6호
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• pp.2767-2772
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• 2013

균형은 일상생활의 기본적인 요소이며 균형능력의 평가는 무게중심의 측정으로 한다. 본 연구에서는 뇌졸중 환자를 대상으로 균형 능력을 평가하기 위한 Balancia 프로그램의 신뢰도와 타당도를 측정하고자 하였다. COP의 측정을 위한 장비로는 Wii Balance Board를 이용하였다. 연구는 39명의 뇌졸중 환자들 대상으로 하였다. 신뢰도 검사는 동요거리, 동요속도, area95% 결과값의 검사자간 신뢰도와 검사자내 신뢰도를 실시하였다. 검사자내 신뢰도는 검사-재검사의 방법으로 급간내 상관계수를 측정하여 ICC .793-.939로 높은 신뢰도를 보였고, 검사자간 신뢰도에서도 ICC .791-.955로 높은 신뢰도를 보였다. 타당도는 Accusway와 비교하여 ICC .851-.955로 매우 높은 일치도를 보였다. 따라서 본 연구를 통해 Balancia 프로그램이 뇌졸중 환자의 균형 능력을 평가하는데 높은 신뢰도와 타당도를 가진 프로그램으로 입증되었다.

• The Journal of Korean Physical Therapy
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• 제24권2호
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• pp.134-142
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• 2012

Purpose: This study examined the effect on postural control during the stimulation of haptic touch with fingertip on the stable surface at quiet standing posture, squat flexion stage, 60 degrees squat stage and squat extension stage. Methods: The postural sway was measured on the force platform, while 30 subjects were squatting, under three different haptic touch conditions (No Touch [NT], Light Touch [LT], Heavy Touch [HT]), above the touch pad in front of their body midline. Three different haptic touch conditions were divided into 1) NT condition; squatting as right index fingers held above the touch pad, 2) LT condition (<1N); squatting as the touch pad was in contact with right index fingers pulp with a pressure not exceeding 1N and 3) HT condition; squatting as subjects were allowed to use the touch pad for mechanical support by transmitting onto it with as much force, choosing with their index fingers. Results: There was significant decrease in LT, rather than that of NT (p<0.01), and in HT, rather than that of LT (p<0.01), as the results of the distance and velocity of center of pressure (COP) in mediolateral direction at quiet standing position. In anteroposterior direction, the distance and velocity of COP in LT and HT showed significant decrease, when compared to that of the data of NT (p<0.01). There was no significant difference between the 3 conditions (NT, LT, and HT), with respect to the distance and velocity of COP in mediolateral direction, during dynamic balance (squat flexion stage, squat extension stage) (p>0.05). In anteroposterior direction, the results of the distance and velocity of COP in HT showed significant decrease when compared to that of the data of NT (p<0.05). Conclusion: Light touch, during the task, decreased the postural sway at static balance. The results suggest that haptic touch should be applied, appropriately, because it varies the effects according to different conditions.

• 한국운동역학회지
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• 제19권3호
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• pp.519-528
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• 2009

상해 예방을 위해 이용하는 테이핑의 효과는 이미 선행연구들에서 이해할만하게 이야기 되어져 왔지만, 기능적 발목 불안정성을 가진 대상자에게 동적 임무를 가지고 지면반력과 안정성을 분석한 연구는 거의 없다. 본 연구는 발목 불안정성을 가진 선수들을 대상으로 점프 후 착지 시 지면반력 변인과 안정성에 미치는 영향을 알아보는데 있다. 이 실험을 위하여 기능적 발목 불안정성을 가진 14명의 선수가 참가하였고 동작분석과 지면반력 값을 산출하기 위해 적외선 카메라 8대(Vicon MX-F20, Oxford Metric Ltd, Oxford, UK)로 구성된 동작분석시스템(Vicon Motion Systems)과 지면반력기를 사용하였다. 본 연구 결과 발목 불안정성이 있는 선수에게 테이핑의 적용은 착지 시 배측굴곡 각속도, 내번 각속도, 최대 수직지면반력을 감소시켰으며, 안정성과 관련된 변인인 A-P cop, M-L cop에서 안정성을 향상시켰다. 임상에서 발목 불안정성이 있는 선수들에게 상해 예방을 위한 하나의 방법으로 테이핑의 사용을 권장해도 될 것으로 사료된다.

• 한국운동역학회지
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• 제26권3호
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• pp.265-272
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• 2016

Objective: The aim of this study was to analyze X-factor, triple X-factor, and the center of pressure (COP) according to the feel of golf driver swing. Method: For this research, 9 golfers from the Korea Professional Golfers' Association (age: $30.11{\pm}2.98yrs$, height: $178.00{\pm}8.42cm$, weight: $76.22{\pm}8.42kg$, experience: $10.06{\pm}3.11yrs$) were recruited to participate in the experiment. Twelve Motion Analysis Eagle-4 cameras were installed and an image analysis was conducted by using the NLT (non-linear transformation) method, and 2 units of Kistler type 5233A dynamometer were used to measure ground reaction force. The sampling ratio was set at 1000 Hz. The golfers each took 10 swings by using their own driver, and chose the best and worse feel from among 10 shots. A paired-sample t-test was used to analyze the results. Results: In regard to feel, no change in head speed, X-factor, and the triple X-factor's X-factor stretch, hip rise, and head swivel, was observed (p>.05). Regarding ground reaction force, a difference was observed between the top of the backswing (p<.05) and impact (p<.05) in the vertical force of the left foot. For COP, a difference was also observed between the mid backswing (p<.001), late backswing (p<.001), and top of the backswing (p<.05) for the right foot X-axis and Y-axis mid follow through (p<.01). Conclusion: It can be reasoned that, irrespective of feel, the head speed, X-factor and triple X-factor's X-factor stretch, hip rise and head swivel did not have an effect on drive distance for domestic golfers, and the vertical reaction force of the left foot and left-right movement span's pressure dispersal of the right foot had an increasing effect on drive distance.

• Journal of Biosystems Engineering
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• 제39권1호
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• pp.34-38
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• 2014

Purpose: In this study, the performance of cooling system with the water-water heat pump system of 100kW scale made for cooling agricultural facilities, especially for horticultural facilities, was analyzed. It was intended to suggest performance criteria and performance improvement for the effective cooling system. Methods: The measuring instruments consisted of two flow meters, a power meter and thermocouples. An ultrasonic and a magnetic flow meter measured the flow rate of the water, which was equivalent to heat transfer fluid. The power meter measured electric power in kW consumed by the heat pump system. T-type thermocouples measured the temperature of each part of the heat pump system. All of measuring instruments were connected to the recorder to store all the data. Results: When the water temperature supplied into the evaporator of the heat pump system was over $20^{\circ}C$, the cooling Coefficient Of Performance(COP) of the system was higher than 3.0. As the water temperature supplied into the evaporator, gradually, lowered, the cooling COP, also, decreased, linearly. Especially, when the water temperature supplied into the evaporator was lower than $15^{\circ}C$, the cooling COP was lower below 2.5. Conclusions: In order to maintain the cooling COP higher than 3.0, we suggest that the water temperature supplied into evaporator from the thermal storage tank should be maintained above $20^{\circ}C$. Also, stratification in the thermal storage tank should be formed well and the circulating pumps and the pipe lines should be arranged in order for the relative low-temperature water to be stored in the lower part of the thermal storage tank.

• 설비공학논문집
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• 제20권9호
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• pp.590-598
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• 2008

In this study, performance of R170/R290 mixtures is measured on a heat pump bench tester in an attempt to substitute R22. The bench tester is equipped with a commercial hermetic rotary compressor providing a nominal capacity of 3.5kW. All tests are conducted under the summer cooling and winter heating conditions of $7/45^{\circ}C$ and $-7/41^{\circ}C$ in the evaporator and condenser respectively. During the tests, the composition of R170 is varied from 0 to 10% with an interval of 2%. Test results show that the coefficient of performance (COP) and capacity of R290 are up to 15.4% higher and 7.5% lower than those of R22 for both conditions respectively. For R170/R290 mixture, the COP decreases and the capacity increases with an increase in the amount of R170. The mixture of 4%R170/96%R290 shows the similar capacity and COP as those of R22. For the mixture, the compressor discharge temperature is $16{\sim}30^{\circ}C$ lower than that of R22. There is no problem with mineral oil since the mixture is mainly composed of hydrocarbons. The amount of charge is reduced up to 58% as compared to R22. Overall, R170/R290 mixture is a good long term 'drop-in' candidate to replace R22 in residential air-conditioners and heat pumps.

• 설비공학논문집
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• 제29권1호
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• pp.7-14
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• 2017

This study carried out a numerical analysis of the effects of hot waste water supply on the performance of a Type II absorption heat pump. There are two types of hot waste water supply, regular series flow and reverse series flow. Also it investigated the interaction between each type of flow and heat exchange solutions. As the effectiveness of heat exchange solutions increase, the steam generation and (COP) increase as well. If the effectiveness of a heat exchange solution is lower than 0.566, the steam generation rate of the reverse flow is lower than that of the regular series flow. A high effectiveness of heat exchange solution is therefore required to make a larger amount of steam in reverse series flow than with ordinary series flow. The COP difference between the two types of flow decreases with the increasing effectiveness of the heat exchange solution. Thus, a reverse flow type absorption heat pump can match the high steam generation rate and COP of the ordinary flow type when a highly effective heat exchange solution is applied.

• 한국콘텐츠학회논문지
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• 제14권9호
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• pp.120-130
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• 2014

이 연구는 여성 노인들에게 15주간 라인 댄스 운동 프로그램을 실시하게 한 후 자세 제어와 반응 메커니즘을 관찰할 목적으로 균형성 요인을 분석해 낙상 예방을 위한 운동 중재 효과를 규명하고자 했다. 이를 위해 65세 이상 16명이 선정되었다. 균형성 판단 요인은 정적 직립 상태에서 압력 판에서 25초 서있는 동안 압력 판의 6가지(3방향 힘, 3방향 모멘트) 자료를 수집해 이를 바탕으로 좌우 및 전후 압력중심 변동폭, 이들의 압력 중심 속도, 흔들림 면적을 분석했다. 분석한 결과 라인 댄스 활동 후 전후 압력 중심의 변화 범위(p<.01)와 압력 중심의 평균 속도(p<.05)는 크게 감소를 보였다. 또한 흔들림 면적은 라인댄스 후 유의한 감소를 보였다(p<.001). 좌우 방향의 압력중심 범위와 속도는 큰 감소를 보이지 않았다. 앞으로 이와 유사한 연구를 수행하고자 할 때는 운동 중재 효과를 실제 낙상과 관련해 연구할 필요가 있으며, 또한 균형성 판단 요인을 신체계뿐만 아니라 전정계, 감각계 등을 관찰하는 연구가 필요하리라 본다.