• 대한한방소아과학회지
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• 제14권2호
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• pp.1-32
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• 2000

It has long been known that SOAT is effective for sudden palpitation occurring unexpectedly in Oriental Medicine. However, effect of SOAT on the isolated heart has not been studied yet. The purpose of this study is to investigate the effect of SOAT on hemodynamics and ECG of isolated rat hearts induced by electrical stimulation using Langendorff perfusion apparatus for nonworking heart. SOAT extract was manufactured by water-alcohol precipitated method. Sprague-Dawley rats weighting $120{\sim}150g$ were used for the experiments, Subject animals were divided into four groups, which are consisted of 1) control(Group orally administered by normal saline 1ml for 14days), 2) sample A(Group orally administered by SOAT extract 1ml for 14days), 3) sample C(Group injected by SOAT extract 0.5ml after stimulation, 4) sample C(Group injected by SOAT extract 1ml after stimulation. To evluate the effects of SOAT on hemodynamics and ECG of isolated rat heart induced by stimulation, heart rate, left ventricular pressure, systolic power, diastolic power, coronary artery perfusion volume and ECG were measured using Langendorff apparatus in both stimulation mode(5 volts, 450 beats/min) and arrythmic mode(5 volts, 420 beats/min including 60 beats/min) The results obtained are as follows : 1. After receiving stressful electrical stimuli, isolated heart showed the heart rate, left ventricular pressure, systolic power, diastolic power, coronary artery perfusion volume were all decreased temporarily, but perfusion continued longer recovery to the control state appeared. However, the coronary artery perfusion volume diminished continuously. 2. The heart rates did not change significantly with both stimulation mode and arrhythmic mode, among experimental groups. 3. The left ventricular pressure showed with both stimulation mode and arrhythmic mode, the significant changes(p<0.05) especially in the injection sample group. In case of stimulation mode, low concentration injection group(0.5ml) was more significantly increased rather than high concentration group(1ml) and in case of arrhythmic mode, high density group(1ml) was so increased than the other(0.5ml). 4. For the systolic power and diastolic power, no significant changes were noticed in the stimulation mode, but in the arrhythmic mode of injection sample groups, significant change(p<0.05) was noticed in both systolic power and diastolic power. Specially the high concentration group(1ml) showed more significant increase than the low concentration group. 5. For the coronary artery perfusion volume, no significant change difference among sample groups was observed in both the stimulation mode and the arrhythmic mode. 6. For the ECG recordings, arrhythmia was induced by electrical stimulus of arrythmia mode and after the stimulus was removed, irregular wave appeared temporarily, but as perpusion continued, recovery to the control state was abtained like the stimulation mode. According to the above results, SOAT significantly changed the hemodynamic data from the electrically stressed, isolated hearts of connected Langendorff perfusion apparatus and we propose SOAT has the direct effects on the muscular function of heart.

• 소성∙가공
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• 제11권8호
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• pp.682-690
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• 2002

The formation of adiabatic shearband in tungsten heavy alloys(WHA) was studied in this investigation. Five prismatic specimens were loaded by high velocity impacts and treated as plane strain problems. To find out the effect of particle's volume ratio, specimens containing 81%, 93% and 97% volume percents of tungsten particles were used. Also the effects of particle's geometry and size on the formation of shearband were studied for 81% volume percent alloys by small size particle model, large size particle model and undulated particle models, and the results were discussed.be used to diagnose the causes of necking and fracture in industrial practice and to investigate whether these defects were caused by material property variation, changes in lubrication, or incorrect press settings. In non-axisymmetric deep drawing, three modes of forming regimes are found: draw, stretch, plane strain. The stretch mode for non-axisymmetric deep drawing could be defined when the major and minor strains are positive. The draw mode could be defined when the major strain is positive and minor strain is negative, and plane strain mode could be defined when the major strain is positive and minor strain is zero. Through experiments the draw mode was shown on the wall and flange are one of a drawn cup, while the plane strain and the stretch mode were on the punch head and the punch corner area respectively, We observed that the punch load of elliptical deep drawing was decreased according to increase of die corner radius and the thickness deformation of minor side was more large than major side.

• 한국유체기계학회 논문집
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• 제18권4호
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• pp.49-55
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• 2015

The pumped storage plant operates with quick change of the discharge as well as quick changes between pump mode and turbine mode. This study focuses on the cavitation analysis of a pump-turbine model because in turbo-machinery, cavitation can reduce the performance and shorten service life. The pump-turbine model system consists of 7 blades, 20 stay vanes (including tongue) and 20 guide vanes. This study adopts the Rayleigh-Plesset model as a cavitation model, which illustrates cavitation by using the air volume fraction method. The pump mode and turbine mode at the operating condition of partial loading, normal and excessive loading are analyzed to investigate the cavitation performance of the pump-turbine. It was observed that this pump-turbine design showed very good cavitation characteristics with no cavitation bubbles in all operating conditions. Overall value of air volume fraction of both mode at different operating condition are lower than 1, which confirms low possibility of cavitation occurrence at current situation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.385-387
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• 1994

Optical interconnections are more attractive than electronic interconnections because of their higher speed, freedom from planar constraints, immunity to electromagnetic interference effects and higher interconnection capacity. Volume hologram is one of the best way to implement optical interconnections. Diffraction efficiency and crosstalk effect are very important things for ensuring independent interconnections. Recently, a general systematic method that can handle a large number of superposed volume gratings in anisotropic host material is presented. In this study for numerical analysis of diffraction, above method is programmed in general form near Bragg angle. Diffraction orders for variation of grating strength are determined by comparing with the coupled-mode method. The effects of parameter variation are considered. Parameters include vertical and azimuthal incident angle, wavelength and interaction length. Diffraction analyses are also performed for intra-mode and inter-mode diffractions.

• Advances in concrete construction
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• 제5권6호
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• pp.613-624
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• 2017

In this paper, an experimental investigation was carried out to study the effect of volume fraction of fiber and maximum aggregate size on mode-I fracture parameters of high strength concrete. Total of 108 beams were tested on loading frame with three point loading, the variables in the high strength concrete beams are aggregate size (20 mm, 16 mm and 10 mm) and volume fraction of fibers (0%, 0.5%, 1% and 1.5%). The fracture parameters like fracture energy, brittleness number and fracture process zone were analyzed by the size effect method (SEM). It was found that fracture energy (Gf) increases with increasing the Maximum aggregate size and also increasing the volume of fibers, brittleness number (${\beta}$) decreases and fracture process zone (CF) increases.

• 한국농공학회지
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• 제39권6호
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• pp.67-79
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• 1997

The perpose of this study was to suggest the experimental characteristic of the Cherepnov Water Lifter following the drain mode. The Cherepnov Water Lifter(CWL), which is powered by the potential energy of water, can be set to operate automatically when the water m a tank is drained. In this study, a CWL is constructed in the valve drain controlling mode(VCM) and the siphon drain controlling mode(SCM), and a pressure transducer is installed. It was found that, in the VCM, intake flow volume is proportional to both delivery flow volume and drain flow volume. In the SCM, intake flow volume is proportional to drain flow volume, and the average delivery rate is proportional to both efficiency and the water utilization ratio. Also, in the VCM, the water utilization ratio is 35~49%, efficiency is 62~9O%, average delivery rate is 12.8~81.2$cm^3$/s, and the average drain rate is 14.O~91.5c$cm^3$/s. On the contrary in the SCM, the water utilization ratio is 1.7~38%, efficiency is 3~58%, average delivery rate is 3.1 ~69.2$cm^3$/s, and the average drain rate is shown as 114.5~ 183$cm^3$/s. As a result of the water utilization ratio, efficiency, average delivery rate, and average drain rate are compared, the VCM is found to be superior and the more economical mode. However, the VCM requires manpower and electricity to operate the electronic machinery involved, while the SCM requires no manpower or electricity at all. An economic evaluation of these differences will be necessary in the future. Also, in the SCM, studies to improve water utilization ratio and efficiency, to find the optimum height of the siphon for decreasing the average drain rate, and to determine the radius of curvature of throat have to be conducted in advance, since a large flow rate is drained during the priming action of the siphon.

• 한국항공우주학회지
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• 제39권1호
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• pp.69-75
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• 2011

우리나라는 우주 개발의 일환으로 달 탐사를 위한 달 탐사선과 달 착륙선의 발사를 계획하고 있다. 향후 멀티미디어 기반의 달 탐사 정보를 전송하기 위해서는 대용량 Telemetry 데이터를 전송하기 위한 통신 시스템을 구축하는 것이 필요하다. CCSDS 표준에서는 신뢰성 있는 원거리 심우주 통신 시스템을 위한 ARQ 기법으로 Deferred NAK mode를 권고하고 있다. 본 논문에서는 달 탐사선과 지상국 및 우주 환경 모델을 반영하여 Deferred NAK mode 통신 시스템 시뮬레이터를 구현하며, 시뮬레이터에는 대용량 Telemetry 데이터를 전송하기에 적합한 변조 방식과 터보 부호화 기법을 사용한다. 시뮬레이션을 통해 Telemetry 데이터의 전송 성능을 분석한다.

• 핵의학기술
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• 제21권1호
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• pp.54-59
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• 2017

폐암(Lung cancer) 환자의 경우 PET/CT 검사에서 호흡으로 인하여 영상의 정합오차가 발생하게 되는데 이로 인해 정확한 SUV 와 Tumor volume측정을 방해하는 요인으로 작용된다. $SUV_{max}$를 이용하여 폐암 환자의 수술 후 예측 및 항암화학요법의 효과를 평가하고 있으며, 방사선치료의 예후 예측 및 평가를 위해 현재 Tumor volume과 SUV를 이용한 지표가 사용되고 있다. 그렇기 때문에 정합오차를 줄이기 위해 본원에서는 Respiratory gating method를 적용하여 검사를 시행하고 있다. 본 연구는 Step and Go 방식이 아닌 Flow mode를 적용하여 Non-gating 영상과 첫 번째 Respiratory Gating영상, 그리고 추가로 부분 Respiratory gating 촬영하여 Respiratory gating method의 유용성에대해 알아보았다. 2016년 6월부터 2016년 9월까지 분당서울대학교병원에서 PET/CT 검사를 한 폐암 환자 20명(남:12명, 여:8명)을 대상으로 amplitude rang 15% 미만인 호흡이 안정한 환자군 10명 15%초과한 호흡이 불안정한 환자군 10명으로 나누어 비교분석하였다. 전체 환자에서 Non-gating 영상의 $SUV_{max}$는 $9.43{\pm}3.93$, $SUV_{mean}$은 $1.77{\pm}0.89$, Tumor Volume은 $4.17{\pm}2.41$로 측정되었고 기존 Gating 영상에서 $SUV_{max}$는 $10.08{\pm}4.07$, $SUV_{mean}$은 $1.75{\pm}0.81$, Tumor Volume은 $3.56{\pm}2.11$로 측정되었다. 그리고 추가 Lung gating 영상에서 $SUV_{max}$는 $10.86{\pm}4.36$, $SUV_{mean}$은 $1.77{\pm}0.85$, Tumor volume은 $3.36{\pm}1.98$을 얻었다. Non-gating 영상과 기존 Gating 영상, 그리고 기존 Gating 영상과 추가 Lung gating 영상을 비교했을 때 둘 다 $SUV_{mean}$ 값에서 통계적으로 유의한 차이를 보이지 않았으나(P>0.05) $SUV_{max}$와 Tumor volume에서 유의한 차이를 보였다(P<0.05). 그중 호흡이 안정한 환자군보다 호흡이 불안정한 환자군에서의 증감률이 더 크게 나타났다. Amplitude range 폭은 전체 20명 중 12명(Signal이 안정된 환자 3명 불안정한 환자 9명)이 추가 Lung gating을 했을 때 기존 Gating 영상보다 더 낮게 나타났다. 본 연구에 의하면 Flow mode를 적용하여 Respiration Gating Method로 촬영한 결과 추가적인 CT 촬영 없이 호흡으로 인해 발생하는 병변의 움직임을 보정해 주어 $SUV_{max}$, Tumor volume을 Non-gating 영상보다 더 정확하게 측정할 수 있었다. 그리고 처음 Gating 할 때보다 추가 촬영 시 호흡의 안정에 따른 Amplitude range 폭의 낮아짐을 알 수 있었다. 따라서 Gating 영상이 Non-gating 영상보다 진단에 더 유용한 정보를 제공함을 알 수 있었고, Signal이 불규칙적인 환자에게 시간적 여유가 있다면 추가로 부분 촬영을 하는 것이 도움이 될 것이라고 사료된다.

• Journal of the Optical Society of Korea
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• 제1권2호
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• pp.67-73
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• 1997

Light wave diffraction from multiple superposed volume gratings is inestigated using a perturbative iteration method of the integral equation of Maxwell's wave equation. The host material and index gratings are anisotropic and non-coplanar multiple volume gratings are considered. In this method, the paraxial approximation and lack of backward scattering in conventional coupled mode theory are not assumed. Systematic analysis of anisotropic wave diffraction due to multiple noncoplanar volume index gratings is performed in increasing level of diffraction orders corresponding to successive iterations.

• 한국소음진동공학회논문집
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• 제22권3호
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• pp.223-233
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• 2012

This paper deals with free vibrations of the tapered Timoshenko beam with constant volume, in which both the rotatory inertia and shear deformation are included. The cross section of the tapered beam is chosen as the regular polygon cross section whose depth is varied with the parabolic function. The ordinary differential equations governing free vibrations of such beam are derived based on the Timoshenko beam theory by decomposing the displacements. Governing equations are solved for determining the natural frequencies corresponding with their mode shapes. In the numerical examples, three end constraints of the hinged-hinged, hinged-clamped and clamped-clamped ends are considered. The effects of various beam parameters on natural frequencies are extensively discussed. The mode shapes of both the deflections and stress resultants are presented, in which the composing rates due to bending rotation and shear deformation are determined.