• Tuberculosis and Respiratory Diseases
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• 제66권2호
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• pp.141-151
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• 2009

연구배경: 과거 국내외 특발성 간질성 폐렴(IIP)의 역학 조사는 제한적이었다. 간질성 폐질환에 대한 관심이 증가하고 있고 국내 IIP 환자들의 분포 및 역학에 대해서 알려진 바 없어 이를 알아보고자 하였다. 방 법: 2003년 1월 1일부터 2007년 12월 31일 사이에 진단된 환자들을 대상으로 하였으며, 진단은 ATS/ERS 기준에 따랐다. 결 과: 입력된 환자는 3,156명이었으나, 중복, 진단기준 미달, 부정확한 자료로 970명이 제외되어 총 2,186명을 분석하였다. 남녀 비는 약 2 : 1이었고 이들의 평균 나이는 65세(11-94세)였다. 빈도는 특발성 폐 섬유화증(IPF) 1,685명(77.1%), 비특이적 간질성 폐렴(NSIP) 261명(11.9%), 특발성 기질화 폐렴(COP) 186명(8.5%), 급성 간질성 폐렴(AIP) 24명(1.1%), 박리성 간질성 폐렴(DIP) 19명(0.9%), 호흡성 세기관지염-간질성 폐질환(RB-ILD) 9명(0.4%), 림프구성 간질성 폐렴(LIP) 2명(0.1%)였다. 평균 나이는 IPF 67.8세, COP 57.7세, NSIP 57.1세로 IPF 환자의 나이가 가장 많았다. 전체 환자를 대상으로 하였을 때, 운동 시 호흡곤란은 68.9%, 기침 60.8%, 객담 32.5%, 흉통 6.8%, 객혈 2.2%, 무증상 4.5%로 운동 시 호흡곤란의 증상이 가장 많았다. IPF의 3년 생존율은 62%였고, NSIP와 COP의 5년 생존율은 모두 85%였다. 결 론: 이 조사는 국내의 IIP 치료 및 진료 지침을 제작에 유용한 도움을 줄 것으로 판단된다.

• 대한의용생체공학회:의공학회지
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• 제28권5호
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• pp.647-656
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• 2007

The purpose of this study was to analyze the effects of vibratory stimulus as somatosensory inputs on the postural control in human standing. To study these effects, the center of pressure(COP) was observed while subjects were standing on a stable and an unstable support with co-stimulated mechanical vibrations to flexor ankle muscles(tibialis anterior tendon, achilles tendon) and two plantar zones on both foot. The COP sway measurement was repeated twice in four conditions: (1) with visual cue and vibration, (2) without visual cue and vibration, (3) with visual cue and without vibration, (4) without visual cue and with vibration. The calculated parameters were the COP sway area and the distance, the median frequency and the spectral energy of COP sway in three intervals $0.1{\sim}0.3,\;0.3{\sim}1,\;1{\sim}3Hz$. The results showed that vibratory stimulus affect postural stability. The reduction rate of the COP sway with vibratory stimulus were higher on the unstable support because the effect of postural stability increases when afferent nervous flow is more activated by vibration on unstable support. If unclear visual or vibratory information is received, one type of information is compared with the other type of sensory information. Then the input balance between visual and vibratory information is corrected to maintain postural stability. These findings are important for the rehabilitation system of postural balance control and the use of vibratory information.

• 대한인간공학회지
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• 제24권1호
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• pp.1-7
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• 2005

This paper investigates the effects of scene movements on cybersickness to develop the guidelines of scene movements in virtual environments. The types of scene movements were made for both scene navigations(through the axes of X: lateral, Y: fore & after, and Z: vertical) and scene rotations(by pitch, roll and yaw). And there were each three levels of speed; 2.7, 4.5 and 6.3 /s(for navigation), and 10, 20 and 30 /s(for rotation) were conducted. Twelve participants were exposed to each scene for 15 minutes, and three tests were performed to measure the degree of sickness. Before and after subjects were exposed to virtual environments, they were requested to describe their sickness symptoms by means of answering the Simulator Sickness Questionnaire(SSQ). And the postural stability tests, in which the Center of Pressure(COP) of subjects were traced and recorded by a 'force platform', were conducted. During the exposure on virtual environments, the subjects were requested to rate the degree of nausea. For both navigation and rotation, the effects of speeds and axes were significant in the SSQ scores and the nausea ratings, while it was not in the COP. The correlation between the SSQ scores and the COP data was not found. Therefore, it was inappropriate to use COP as a measure of cybersickness. The degree of sickness increased, except for the case of the yaw, as the speed increased. The sickness was most severe in the scene navigation through the axis X and in the scene rotation by the yaw.

• 설비공학논문집
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• 제19권5호
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• pp.372-378
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• 2007

GHX (Geothermal Heat Exchanger) design which determines the performance and initial cost is the most important factor in ground source heat pump system. Performance of GHX is strongly dependent on the thermal resistance of soil, grout and pipe. In general, GHX design is based on the static simulation program. In this study, dynamic simulation has been peformed to analyze the variation of system performance for various GHX parameters. Line-source theory has been applied to calculate the variation of ground temperature. The averaged weather data measured during a 10-year period $(1991\sim2000)$ in Seoul is used to calculate cooling and heating loads of a building with a floor area of $100m^2$. The simulation results indicate that thermal properties of borehole play significant effect on the overall performance. Change of grout thermal conductivity from 0.4 to $3.0W/(m^{\circ}C)$ increases COP of heating by 9.4% and cooling by 17%. Change of soil thermal conductivity from 1.5 to $4.0W/(m^{\circ}C)$ increases COP of heating by 13.3% and cooling by 4.4%. Change of GHX(length from 100 to 200 m increases COP of heating by 10.6% and cooling by 10.2%. To study long term performance, dynamic simulation has been conducted for a 20-year period and the result showed that soil temperature decreases by $1^{\circ}C$, heating COP decreases by 2.7% and cooling COP decreases by 1.4%.

• 설비공학논문집
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• 제18권9호
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• pp.753-760
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• 2006

The purpose of the present work is to investigate the influence of the refrigerant adulteration by LiBr solution on the cooling capacity and COP for three different types of abso게tion chillers: a single-effect type, a series-flow double-effect type and a parallel-flow with double-effect type. A simulation program has been prepared for the cyclic analysis of absorption chillers. With some assumptions, the calculations have been performed by solving the mass balance equation, energy balance equation and the state equation simultaneously. The range of the LiBr concentration of refrigerant was 0% to 20% in the present study. For the single-effect absorption chiller, the maximum decrease in the cooling capacity was 10% at the 20% of LiBr concentration. For the double-effect chiller, the capacity was decreased by 11.1% for the parallel-flow type and the series-flow type. Also, the COP was reduced by 3.0% in single-effect, 2.8% in series-flow type (SR=0.4) and 2.3% in parallel-flow type.

• 한국기계가공학회지
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• 제16권3호
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• pp.24-29
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• 2017

In this study, a seat cross member was fabricated by optimizing the resin transfer molding processing of CFRP (Carbon Fiber Reinforced Plastics) materials. This seat cross member is used in automotive underbody parts and provides side impact support. The seat cross was manufactured via vacuum resin transfer molding. The process included 1min of resin injection, 8 mins of heating, and 1 min of cooling, for a total molding time of 10mins. Tensile test results showed an average breaking load of 21.50kN, a tensile strength of 404 MPa, and an elastic modulus of 46.2 GPa. As a result, the CFRP seat cross provides the same strength as a similar steel part, but weighs 42% less.

• PNF and Movement
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• 제8권1호
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• pp.67-77
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• 2010

Purpose : The purpose of this study was to investigate the usefulness of clinical balance tests through the correlation of balance evaluation using by forceplate in elderly. Methods : Thirty nine healthy elderly subjects (14 males, 25 females) participated in the study. The subjects were evaluated with clinical balance tests [(Berg balance scale (BBS), Functional reach test (FRT), Tinetti's performance oriented mobility assessment (POMA), and one leg standing (OLS)]. Static balance evaluation was assessed by using forceplate. Center of pressure (COP) parameters were obtained using it as total path distance, total sway area, X mean frequency and Y mean frequency for 20 seconds in the following conditions: (1) comfortable standing with eyes opened and closed, (2) uncomfortable standing with eyes opened and closed. After static balance evaluation tested, dynamic balance evaluation was assessed. COP parameters were error distance and area during sine curve trace. COP parameters were movement time, error distance, and maintained time in the circle during COP movement task. Results : Clinical balance tests showed statistically significant correlation between static and dynamic balance evaluations. Among the clinical balance tests, the BBS, POMA, and OLS showed significant correlation with to assess the balance ability of elderly in clinical setting both evaluations. Conclusion : Clinical balance tests can be recommended in clinical setting because of low costs and simplicity.

• 한국태양에너지학회 논문집
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• 제34권1호
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• pp.58-63
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• 2014

A vertical closed loop ground source heat pump (GSHP) is used to produce heat from the low-grade energy source such as the outside air and ground source. It is known that a heat pump system type has better efficiency comparing to the electric heating system. This study only demonstrates that the vertical closed loop GSHP system is a feasible choice for space cooling of air conditioning. The coefficient of performance (COP) is the ratio of heat output to work supplied to the system in the form of electricity. For the vertical closed loop GSHP system in a cooling mode, the COP is the most commonly used way for judging the efficiency. For the purpose of this experiment, vertical closed loop GSHP system was installed in the laboratory and the experiment was executed. As a result, an average COP of vertical-closed loop GSHP system was 3.62 when the outside average temperature was $33^{\circ}C$.

• 대한물리치료과학회지
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• 제16권4호
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• pp.19-27
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• 2009

Background: The purpose of this study was to examine changes of postural sway and weight distribution after cooling the foot. Methods: Ten men with no history of sensory, neurological and orthopedic disorders were participated in this study. They performed four methods: (1) non-treated feet group(control group); (2) both feet treated group; (3) right foot treated group; and (4) left foot treated group. The feet of them were put into ice box, then they stood more than forty seconds on EMED system with bared feet. Data on the moving length, velocity, and maximum velocity of COP and the weight distributions during thirty seconds only were measured in standing position. Results: (1) The moving length and velocity of COP were significant difference between control group and both feet treated group only(p<0.05). (2) The maximum velocity of COP was significant difference among control group and all experimental groups. (3) The changes of weight distribution were significant difference among control group and right/left foot treated groups. Conclusions: Cooling the foot led to increased postural sway and changed weight distribution patterns.

• Journal of Advanced Marine Engineering and Technology
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• 제35권2호
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• pp.182-188
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• 2011

본 논문은 R744-R404A용 캐스케이드 냉동시스템의 기초 설계자료를 제공하기 위해서 성능특성에 대해 분석하였다. 작동변수로는 R404A용 고온사이클과 R744용 저온사이클의 과냉각도와 과열도, 압축효율, 응축과 증발온도이다. 이에 대한 주요결과를 요약하면 다음과 같다. 고온사이클에만 과열도를 주는 것이 가장 높은 COP를 가지는 반면에 저온 고온사이클 모두에 대해 과냉도를 주는 것이 가장 높은 COP를 가진다. 과열도, 과냉각도, 압축효율, 증발온도, 응축온도 등의 인자들이 R744와 R404A용 캐스케이드 냉동사이클의 COP에 영향을 미치는 것을 확인할 수 있었고, 이들 각각의 인자들은 캐스케이드 냉동사이클의 성능을 최대로 하는 캐스케이드 증발온도가 존재함을 알 수 있었다.