• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.138-140
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• 2009

Hemorrhage shock occupies high rate in trauma patient's mortality and blood pressure is the variance that judges early diagnosis and the effect of remedy. Systolic blood pressure is related to pulse transit time(PTT). PTT means the time that is required to flow from the heart to peripheral artery. PTT is influenced from the length, cross section and stiffness of the blood vessels. It is hard to evaluate the correlation between systolic blood pressure and PTT because they are variable in human body. In this paper, we evaluated the correlation between the systolic blood pressure and PTT in normal and hemorrhage states using standardized rat. PTT is defined as the time differences between the R peak and the peak of pulse wave. The analyzed time differences of ECG and blood pressure are analyzed every 5minutes for 30 seconds when there is before and after bleeding. Before bleeding, systolic blood pressure and PTT are steadily preserved but when the bleeding comes started, systolic blood pressure is declined. However PTT was increased and decreased. Under the circumstance that the standardized rat is controlled by age, the length of the blood vessels, and any disease, it shows that PTT measurement using systolic blood pressure of bleeding is impossible.

• 대한조선학회논문집
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• 제53권2호
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• pp.144-153
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• 2016

This paper aims to demonstrate the design, structure analysis, and hydrostatic pressure test of the cylinder used in 2000m water depth. The cylinder was designed in accordance with ASME pressure vessel design rule. The 1.5 times safety factor required by the general rule was applied to the design of the cylinder, because ASME rule is so excessive that it is not proper to apply to the hydrostatic pressure test. The finite element analysis was conducted for the cylinder. The cylinder was produced according to the design. The hydrostatic pressure test was conducted at the hyperbaric chamber in KRISO. The results of finite element analysis(FEM) and those of the hydrostatic pressure test were almost the same, which showed that the design was exact and reliable.

• Tuberculosis and Respiratory Diseases
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• 제42권1호
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• pp.84-92
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• 1995

연구배경: 수면무호흡증후군은 호흡정지로 인한 저산소혈증때문에 심 폐부전, 말초혈관 기능장애 혹은 중추신경질환을 유발할 수 있을 뿐만 아니라 갑작스런 사망을 일으킬 수 있는 질환으로 조기진단 및 적절한 치료가 요구된다. 현재까지는 지속적 기도양압 치료가 가장 효과적인 치료법으로 알려져 있으나, 최적양압을 구하기 위하여는 검사자나 환자의 시간과 노력 그리고 경제적 손실이 많은 실정이다. 저자들은 지속적 기도 양압 치료시의 최적양압에 도달하는 시간을 파악하여 전통적 수면다원화검사 및 양압처방에 소요되는 시간과 노력 그리고 경제적 손실을 줄여 보고자한다. 방법: 수면무호흡증후군 환자에서 진단 및 치료적 수면다원화검사를 실시하며 최적 지속적 기도양압은 2Cm $H_2O$부터 시작하여 무호흡이 정상화되고 최저산소포화도가 향상될 때까지 증가시켜 최적압 도달까지 걸린 시간을 측정 분석하였다. 결과: 1) 지속적 기도양압 치료시 치료전보다 총수면시간, 효과적인 수면시간은 유의한 차이가 없었으나, REM 수면, REM 수면에 도달하는 시간, 무호흡지수, 무호흡 저호흡지수, 최저산소포화도는 의의있게 호전되었다. 2) 평균 최적 지속적 기도양압은 $7.7{\pm}2.9Cm\;H_2O$였고, 이 최적압에 도달하는데 걸리는 시간은 $151.5{\pm}91.3$분이었다. 3) 대상환자들의 33%에서 최적압에 도달하는데 4시간 이상이 소요되었으며, 최적압 도달후 다시 압조정이 필요하였던 경우는 60(47%)예 였고, 나머지 67(53%)예에서는 더 이상의 압조정이 필요없이 처음의 최적압으로 효과가 있었다. 결론: 최적 지속적 기도양압치에 도달하는데 환자의 약 1/3에서 4시간 이상 걸리는 것으로 보아 split night CPAP titration 방법은 수정되어져야 할 것으로 생각되며, nap study시의 2~3시간은 적절한 CPAP titration을 하기에는 불충분할 것으로 생각된다.

• KEPCO Journal on Electric Power and Energy
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• 제2권3호
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• pp.403-407
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• 2016

In general, drum-type boilers are designed for base load duty and applied under constant pressure operation mode. Recently, however conditions often occur that even drum-type boilers have to operate at partial load conditions. A feasibility study on adopting the sliding pressure operation for drum-type boiler was conducted, and corresponding performance changes and effects on the equipment were analyzed by utilizing a process simulation model. As a result, the conclusion was reached that drum type boilers are able to adopt the sliding pressure operation and can improve of net efficiency at part load operation in spite of the Rankine cycle efficiency reduction due to the decreases in main steam pressure. Because of thank to improvement of high pressure turbine stage-1 internal efficiency and power savings of boiler feed water pump. The sliding pressure operation is advantageous in terms of stress level relief for boiler tube as well as maintaining the rating steam temperature at part load condition. However, cautions are required because the drum boilers have poor dynamic response characteristics which may get worse during the sliding pressure operation.

• Journal of Advanced Marine Engineering and Technology
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• 제20권5호
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• pp.82-92
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• 1996

A computer simulation with predict the fuel injection rates and the fuel injection pressure behaviors in diesel engine fuel injection systems would by very useful in designing or improving fuel injection systems. In this paper we developed computer program in order to predict the behaviors of the fuel injection rate and the injection pressure for Electronic Hydraulic Ultra-High Pressure Fuel Injection System. We've applied the continuity and momentum equations for the hydraulic phenomena and the dynamics of individual components of the Electronic Hydraulic Fuel Injection System. To solve all the equations numerically we've applied the Runge-kutta IV method. Water hammer equations were applied for the hydraulic pipe solution, and the method of characteristics was employed in our calculations. The simulation results were compared with the experimental results for: Accumulator pressure, Injection pressure and unjection rate. As a result, The simulation results agree very well with our experimental results. We found that a large accumulator and the high speed solenoid valve were required, and the compression volume of the fuel had to be as small as possible in order to acheive ultra-high pressure fuel injection.

• 대한기계학회논문집A
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• 제26권2호
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• pp.399-405
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• 2002

This paper proposes a new type of piezoactuator-driven valve system. The piezoceramic actuator bonded to both sides of a flexible beam surface makes a movement required to control the pressure at the flapper-nozzle of a pneumatic valve system. After establishing a dynamic model, an appropriate size of the valve system is designed and manufactured. Subsequently, a robust H$_{\infty}$ control algorithm is formulated in order to achieve accurate tracking control of the desired pressure. The controller is experimentally realized and control performance for the sinusoidal pressure trajectory is presented in time domain. The control bandwidth of the valve system, which directly represents the fastness, is also evaluated in the frequency domain.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.960-963
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• 2010

In recent days, the development project for industry or housing complex at west coast of Korea is on an increasing trend. the design of soft ground is necessarily required. So, the evaluation of consolidation characteristics for soft ground is very important in design and construction. Especially, the correct evaluation of preconsolidation pressure or OCR for given soft ground is essential at the west coast that has a large tidal range, since it affects the settlement of soft ground. In this study, various methods determining preconsolidation pressure were carried out to investigate the application of each method. The preconsolidation pressure that evaluated from the results of conventional consolidation tests on the songsan clay were compared.

• 한국공간구조학회논문집
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• 제2권1호
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• pp.67-73
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• 2002

Measurement of fluctuating pressure by tube system is carefully designed due to the organ-pipe resonance. It is necessary to correct the pressure before analysis. The three method for correction the distortion fluctuation pressure short tube length and the frequency response functions and insert a restrictor in the tube to increase the damping. The first method is useful when the tube length is short. In second method, the distorted signal through the tubing transformed into the frequency domain, dividing by transfer function and inverse fourier transforming back into the time domain gives the required pressure signal. In this paper three types of tubing which have different length of 100cm, 150cm, 200cm were experimented the distorted signal and correct the distortion signal

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.345-348
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• 2006

In sheet metal forming process using press and draw die some defect can be made because of the high pressure of air pocket between draw die and the product. The purpose of this study is to develop a program to decide an optimal combination of air vent hole size and number to prevent those defect on product. The air inside air pocket is considered as ideal gas and the compression and expansion is assumed as isentropic process. The mass flow is computed in two flow condition: unchocked and chocked condition. The present computation obtains required cross-sectional area of air vent hole for not exceeding the user specified pressure such as the pressure for yielding strength of the product or the pressure for unchocked flow. To validate the program the present results are compared with the results of other researchers and commercial CFD code.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.673-678
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• 2001

This paper proposes a new type of piezoactuator-driven valve system. The piezoceramic actuator bonded to both sides of a flexible beam surface makes a movement required to control the pressure at the flapper-nozzle of a pneumatic valve system. After establishing a dynamic model, an appropriate size of the valve system is designed and manufactured. Subsequently, a robust $H_{\infty}$ control algorithm is formulated in order to achieve accurate tracking control of the desired pressure. The controller is experimentally realized and control performance for the sinusoidal pressure trajectory is presented in time domain. The control bandwidth of the valve system, which directly represents the fastness, is also evaluated in the frequency domain.