• Journal of Chest Surgery
• /
• 제10권2호
• /
• pp.195-204
• /
• 1977

Dynamic lung compliance was measured in healthy ten young[mean age, 26 years] male and five young[mean age, 25 years] female. Lung volume was integrated of the rate of flow signal which was obtained by using pneumotachograph and differential pressure transducer[PM 5, Statham]. Intrapleural pressure was measured as that of intraesophagel pressure. Esophageal ballon, 15. 5cm in length, 4ml of luminal capacity and made of thin latex, was connected to the polyethylene tube that had 12-14 side holes and was of 1.5mm of ID. Transpulmonary pressure was traced by means of differential pressure transducer[PM 131, Statham] to which connected the esophageal balloon catheter and connection tube from mouth piece. Lung volume and transpulmonary pressure were photographed by cathode ray oscilloscope camera while the subjects were breathing spontaneously. Dynamic lung compliance loop was displayed on single trace monitor and subtraction was performed for the quasi-static hysteresis. Dynamic lung compliance was measured, 1. by plotting the pressure-volume relationship 2. from the subtracted pressure-volume loop. Results were as follows. 1. Dynamic lung compliances measured by plotting of healthy young male and female were $0.202{\pm}0.06$ and $0.190{\pm}0.023L/cm$ $H_2O$ respectively. 2. When measured from subtraction loop, dynamic lung compliance for male and female were $0.327{\pm}0.107$, and $0.27{\pm}0.06L/cm$ $H_2O$ respectively. 3. Dynamic chest wall and total respiratory system compliance were also measured. 4. Dynamic lung compliance by plotting appeared to be essentially same when compared to that of static compliance reported previously from our laboratory, however, that obtained from subtraction loop revealed higher values than the compliances obtained by plotting and that of static compliance.

• 대한핵의학회지
• /
• 제35권3호
• /
• pp.152-160
• /
• 2001

목적: 게이트 심근 SPECT를 이용하여 좌심실심근의 최대탄성률을 측정하는 방법의 재현성을 조사하고 단일 압력-부피 고리방법과 매개변수 최적화 방법으로 얻었을 때 재현성의 차이를 조사하였다. 대상 및 방법: 관상동맥질환이 의심되는 47명 (남자 42명, 여자 5명, 평균나이 53세, 좌심실구혈률 22-68%)에서 Tc-99m MIBI게이트 심근 SPECT와 동시에 요골동맥 긴장도를 측정하였다. 이 중 11명에서는 누운 자리에서 움직이지 않고 연이어 두번 측정하였다. 최대탄성률과 영점부피를 Lee 등이 제안한 단일 압력-부피 고리 방법과 Yoshizawa 등이 제안한 선형근사에 의한 매개변수 최적화 방법으로 추정하였다. 결과: 최대탄성률(상관계수 0.96)과 영점부피(상관계수 0.99)의 재현성은 단일 압력-부피 고리 방법이 매개변수 최적화 방법(최대탄성률 0.89, 영점부피 0.64)보다 좋았다. 두 방법으로 추정한 최대탄성률의 상관계수는 0.77, 영점부피의 상관계수는 0.65이었다. 결론: 게이트 심근 SPECT와 동맥긴장도 측정법으로 얻어 단일 압력-부피 고리 방법으로 추정한 좌심실 심근의 최대탄성률의 재현성은 매우 우수하였다. 매개변수 최적화 방법으로 얻은 최대탄성률도 우수하나 단일 압력-부피 고리 방법보다 못하였다.

• 소성∙가공
• /
• 제11권3호
• /
• pp.246-254
• /
• 2002

A simple method to derive an optimal pressure curve, characterized by initial pressure, final pressure and pressure path, has been proposed. The initial pressure has been determined from the condition to prevent recoiling phenomenon in the early stage, while the final pressure is from the FE analysis and pressure path is from the punch penetration volume. In order to realize the pressure curve, an open loop control system based on a proportional relief valve has been developed for the renovated CNC hydroforming press. Through the comparison of experiment and analysis, the predicted pressure curve has been verified optimal curve since no defect has been observed.

• 설비공학논문집
• /
• 제10권4호
• /
• pp.389-397
• /
• 1998

A loop duct system is often found in a VAV-HVAC(variable air volume heating, ventilating and air conditioning) design. It is known that the simple T-method is not be applicable to the loop duct system and cannot be used to calculate the flow rate and the pressure drop at each duct section of the loop duct system. In this paper, the extended T-method has been developed and it is found to be applicable to the loop duct system to which the simple T-method cannot be applied. The validity of the extended T-method has been verified by using to solve for a simple, ideal loop duct system for which there exists analytical solution. In addition, the extended T-method is employed to compute the loop duct system of a real building with an area of 380$m^2$. The results show that the computed flow rate at the exit differs from the designed flow rate by a range of -13.6~43.5 %. Consequently, three design factors must be adjusted in order that the flow rate may be balanced. These include the duct sizes, in terms of their lengths and diameters, the sub-duct locations and the positioning of damper which is found upstream of the exit duct.

• 한국기계가공학회지
• /
• 제10권3호
• /
• pp.53-59
• /
• 2011

In this study, a two-phase closed loop cooling system is desinged and tested for a laptop computer using a FC-72. The cooling system is characterized by a parametric study which determines the effects of existence of a boiling enhancement microstructure, initial system pressure, volume fill ratio of coolant and inclination angle of condenser on the thermal performance of the closed loop. Experimental data show the optium condition when the volume ratio of working fluid is 70%, the pump flowing is 6ml/min, and the inclination angle of condenser is $0^{\circ}$. This research shows the maximum values which can dissipate 33W of chip power with a chip temperature maintained at $95^{\circ}C$.

• International Journal of Fluid Machinery and Systems
• /
• 제9권1호
• /
• pp.1-16
• /
• 2016

Behaviors of surges appearing near the stall stagnation boundaries in various fashions in systems of a single-stage compressor and flow-path systems were studied analytically and were tried to put to order. Deep surges, which enclose the stall point in the pressure-mass flow plane, tend to have either near-resonant surge frequencies or subharmonic ones. The subharmonic surge is a multiple-loop one containing, for example, in a (1/2) subharmonic one, a deep surge loop and a mild surge loop, the latter of which does not enclose the stall point, staying only within the stalled zone. Both loops have nearly equal time periods, respectively, resulting in a (1/2) subharmonic surge frequency as a whole. The subharmonic surges are found to appear in a narrow zone neighboring the stall stagnation boundary. In other words, they tend to appear in the final stage of the stall stagnation process. It should be emphasized further that the stall stagnation initiates fundamentally at the situation where a volume-modified reduced resonant-surge frequency becomes coincident with that for the stagnation boundary conditions, where the reduced frequency is defined by the acoustical resonance frequency in the flow-path system, the delivery flow-path length and the compressor tip speed, modified by the sectional area ratio and the effect of the stalling pressure ratio. The real surge frequency turns from the resonant frequency to either near-resonant one or subharmonic one, and finally to stagnation condition, for the large-amplitude conditions, caused by the non-linear self-excitation mechanism of the surge.

• 한국추진공학회지
• /
• 제16권3호
• /
• pp.34-40
• /
• 2012

가스발생기의 압력 제어기법을 제안하였다. 모델기반 제어법칙을 설계하기 위하여 Robert 식과 보존 방정식을 이용하여 가스발생기의 모델을 구성하였고, 연소시험을 통하여 모델의 정확성을 검증하였다. 모델은 연소 공간이 증가함에 따라 시스템의 고유 특성이 변화하게 되는데, 이러한 특성으로 인한 폐루프 구조에서 나타나는 응답특성을 해석하기 위하여 PID 및 비선형 적응 제어법칙을 설계하였다. 수치 시뮬레이션 결과 두 방법이 각각 제어 성능과 실제 시스템 적용에 문제가 있음을 알 수 있었고, 이를 극복하기 위한 새로운 제어기법을 제안하였다. 새롭게 제안된 이득계획 제어기법의 수치 시뮬레이션 결과 외란 및 측정 잡음의 영향에서도 우수한 제어 응답성능을 보였다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.618-623
• /
• 2011

가스발생기의 압력 제어기법을 제안하였다. 모델기반 제어법칙을 설계하기 위하여 Robert 식과 보존방정식을 이용하여 가스발생기의 모델을 구성하였고, 연소시험을 통하여 모델의 정확성을 검증하였다. 모델은 연소 공간이 증가함에 따라 시스템의 고유 특성이 변화하게 되는데, 이러한 특성으로 인한 폐루프 구조에서 나타나는 응답특성을 평가하기 위하여 PID 및 비선형 적응 제어법칙을 설계하였다. 수치 시뮬레이션 결과 두 방법이 각각 제어 성능과 실제 시스템 적용에 문제가 있음을 알 수 있었고, 이를 극복하기 위한 새로운 제어기법을 제안하였다. 새롭게 제안된 이득계획 제어기법의 수치 시뮬레이션 결과 외란 및 측정 잡음의 영향에서도 우수한 제어 응답성능을 보였다.

• 한국자동차공학회논문집
• /
• 제23권4호
• /
• pp.444-453
• /
• 2015

In the previous study, several problems were observed in a NG conversion vehicle, which were fail of air-fuel ratio closed loop control, aggravated fuel economy, increased harmful emission and declined roadability. It was provisionally supposed that the mismatch of injection system with the engine caused these performance deterioration. In this context, the characteristics of fuel injection system of commercial conversion kit for NG were investigated experimentally varying the engine speed, fuel rail pressure and volume. The results are as follows; The injection quantity decreases as the engine speed increases due to the extremely small rail volume of the presenting system and flow rate of No. 2 injector are always lower than that of the other ones regardless of the speed under the dynamic operation condition. Furthermore the existing system does not meet the required fuel quantity for the normal engine operation over 3000 RPM. On the other hands, the large rail volume systems ease and/or eliminate the difference of injection quantity between the injectors according to the speed variation, however, these systems decrease injection flow rate and still cannot supply sufficient fuel. Finally, suitable combination of the higher rail pressure and the larger rail volume might be a solution about these problems.

• Korean Chemical Engineering Research
• /
• 제58권4호
• /
• pp.665-674
• /
• 2020

외부순환형 공기부양반응기에서 낮은 주파수의 압력 변동에 대해 연구하였다. 상승관과 하강관의 상부와 하부에 설치된 내압관의 액면을 휴대폰으로 촬영하는 방법으로 빠른 주파수의 변동이 제거된 압력을 측정하였다. 자기상관함수와 교차상관함수의 계산을 통해 압력의 주기적인 변동을 확인하였다. 기체속도가 일정하여도 순환액체의 관성으로 인해 압력은 물론이고 상승관과 하강관내의 기체체류량도 주기적으로 변동하였다. 일반적으로 기체유속이 증가할수록 압력 변동의 강도는 커졌다. 비분산 액체높이가 0.04 m일 때 압력 변동의 주기는 기체속도가 0.14 ms^-1에서 극대값을 보여주었다. 이는 기체속도가 커질수록 순환 액체속도의 증가율은 둔화하고 효과적으로 순환하는 액체의 부피가 감소하므로 순환액체의 관성이 극대값을 보이기 때문이다.