• 신재생에너지
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• 제19권4호
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• pp.35-45
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• 2023

Global efforts are focused on achieving carbon neutrality due to the increases in the levels of greenhouse gases. Moreover, the greenhouse gases generated from the disposal of municipal solid waste (MSW) are the primary sources of emissions in South Korea. In this study, we conducted the biological conversion of syngas (CO, H₂, and CO₂) generated from MSW gasification. The MSW-derived syngas was used as a feed source for cultivating Eubacterium limosum KIST612, and pressurization was employed to enhance gas solubility in culture broth. However, the pH of the medium decreased owing to the pressurization because of the CO₂ in the syngas and the cultivation-associated organic acid production. The replacement of conventional HEPES buffer with a phosphate buffer led to an approximately 2.5-fold increase in acetic acid concentration. Furthermore, compared with the control group, the pressurized reactor exhibited a maximum 8.28-fold increase in the CO consumption rate and a 3.8-fold increase in the H2 consumption rate.

• 한국화재소방학회논문지
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• 제26권5호
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• pp.99-104
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• 2012

본 연구에서는 공동주택 화재 시 피난시나리오 및 화재실 배연개구부 유무에 따른 부속실 급기가압 시스템의 성능 및 효용성을 평가하기 위해 각 실의 압력변화 특성을 실험적으로 측정하였다. 그 결과, 화재실문과 계단실문 개폐 시나리오 및 배연개구부의 유무에 따라 압력변화 특성이 크게 달라졌으며 최저설계차압으로 재안정화 되기 전에 부속실 과압 또는 부압 발생, 도어클로져 닫힘 기능 저하 등의 현상이 나타났다. 또한. 급기댐퍼의 설치위치보다는 화재실 배연개구부의 존재가 규정방연풍속 유지에 필수적인 것으로 나타났다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.122-126
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• 2006

터보펌프식 발사체 추진기관의 기체공급계 개발과정을 통하여 두 가지 방식의 가압시스템과 저중량 배관시스템에 대한 국산화 개발을 수행하였다. 서브시스템 시험을 통해 액체산소 얼리지 압력을 일정하게 유지시키기 위한 1단 및 2단 감압방식 가압시스템의 제어 성능을 확인할 수 있었다. 또한 열/유체적 측면과 구조적 측면을 체계적으로 고려하여 배관 시스템의 요구성능을 만족하고 발사체에서 요구되는 수준까지 무게가 저감된 배관 시스템 개발을 개발하였다. 이와 아울러 터보펌프에서의 케비테이션 방지 및 지상 대기시간동안에 배관에서 발생할 수 있는 가이저링을 방지하기 위한 액체 산소 컨디셔닝 기술을 확립할 수 있었다. 또한 가압부/산화제 공급계 연계시험을 통해 시스템 차원의 성능을 확인할 수 있었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.293-297
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• 2009

극저온 가압제를 사용하는 가압시스템에서 가압제의 공급을 차단하기 위하여 많이 사용되고 있는 밸브로는 공압구동밸브나 솔레노이드밸브, 파이로밸브 등이 있다. 공압구동밸브와 솔레노이드밸브는 파이로밸브에 비하여 구조가 복잡하고 무게가 무거운 단점이 있어, 본 연구에서는 극저온 및 고압에 적용이 가능하고 구조가 비교적 간단하고 무게가 가벼운 극저온 헬륨가스용 파이로밸브를 개발하여 내압 및 기밀시험과 진동시험, 극저온 공급시험을 수행하였다.

• 한국주조공학회지
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• 제32권1호
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• pp.24-31
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• 2012

In this study, semi-solid thin plate of A 356 aluminum alloy was fabricated by using slope plate apparatus and vacuum pressurization. Slope plate was used to produce semi-solid material with spheroidal microstructures. After molten metal was poured into the slope plate connected to the pouring hole of die, semi-solid material flowed into the die cavity by vacuum degree. The primary crystals of the cast metal became spheroidal. In order to increase the working pressure, gas pressurization of U shape was designed for fabrication of thin plate. For 3 bar of gas pressure and 60 mmHg of vacuum degree, thin plate was fabricated without defects on surface.

• 한국자동차공학회논문집
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• 제15권3호
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• pp.47-53
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• 2007

To suppress the bubble generated in the liquid LPG direct injector is the most important to develop the LPDi engine. It was found in the previous study that bubbling phenomenon in the injector of the LPDi engine is decisively influenced by pressure of fuel and temperature around the injector. Therefore, in this study, the effect on suppressing the bubbling in the LPDi injector by high pressurization of fuel is analyzed and the spray characteristics are also studied. As a result, it is found that the bubbling in the LPDi injector is radically suppressed when the pressure of fuel is over 50MPa. The bubbling is suppressed when the pressure of fuel is over 3MPa if the inserted position of the injector is considered. Also, it is confirmed that the higher the pressure of fuel is the longer spray tip penetration and is the larger spray angle. As the ambient pressure increases, spray tip penetration decreases and spray angle increases due to the increase of drag force.

• 한국화재소방학회논문지
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• 제25권6호
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• pp.178-183
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• 2011

초고층 건물의 승강기는 혹한기에 연돌효과에 의한 차압 때문에 고층부의 승강기 문틈에서 소음을 유발하고, 1층에서 승강기 문 개폐에 영향을 줄 정도의 강한 압력이 발생하며, 화재시에는 건물 내에 연기를 전파시키는 주된 구동력이 된다. 또한 승강기를 피난용으로 사용하기 위해서도 연돌효과는 반드시 극복되어야 할 과제이다. 이 논문에서는 연돌효과가 고층건물의 승강기 승강로에 미치는 부정적 영향을 줄이기 위해 승강로를 가압하는 방식을 검토하였다. 승강로와 거실 사이를 균압화하고 승강로를 급기 가압하는 조건으로 시뮬레이션 함으로써 NFPA 92A와 IBC 2012에서 요구하는 조건에 근접하는 결과를 얻었다.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.545-553
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• 2016

The failure probabilities of the reactor pressure vessel (RPV) for low temperature over-pressurization (LTOP) and cool-down transients are calculated in this study. For the cool-down transient, a pressure-temperature limit curve is generated in accordance with Section XI, Appendix G of the American Society of Mechanical Engineers (ASME) code, from which safety margin factors are deliberately removed for the probabilistic fracture mechanics analysis. Then, sensitivity analyses are conducted to understand the effects of some input parameters. For the LTOP transient, the failure of the RPV mostly occurs during the period of the abrupt pressure rise. For the cool-down transient, the decrease of the fracture toughness with temperature and time plays a main role in RPV failure at the end of the cool-down process. As expected, the failure probability increases with increasing fluence, Cu and Ni contents, and initial reference temperature-nil ductility transition ($RT_{NDT}$). The effect of warm prestressing on the vessel failure probability for LTOP is not significant because most of the failures happen before the stress intensity factor reaches the peak value while its effect reduces the failure probability by more than one order of magnitude for the cool-down transient.

• 터널과지하공간
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• 제6권3호
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• pp.209-222
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• 1996

Shut-in pressure, reopenting pressure and fracture orientation are very important parameters to be evaluated precisely in in-situ stress measurement by hydraulic fracturing. Graphical methods on pressure-time curves have been conventionally used, even though these are seriously dependent on subjectivity of interpreters. So there have been many demands on new method to objectivity in determining parameters. We have developed integrated hydrofracturing data processing program (HYDFRAC), based on nonlinear regression analysis and can be invoked under the Window graphical user interface. HYDFRAC consiste of three routines, that is shut-in pressure routine, reopening pressure routine, and fracture delineation routine. Each of routines include independent modules according to parameter determination methods. Its application to field tests ensured both objectivity and facility in determining of hydraulic fracturing parameters. Determining shut-in pressures at each pressurization cycles, we adopted the exponential pressure-decay method(EPD method), the bilinear pressure-decay-rate method (PDR method), and the tangent intersection method in order to find the pressurization-cyclic tendency of shut-in pressures. The estimated pressure by PDR method exists in the range of the upper and lower values by EPD method, and lies near to the upper value more than the lower. Being the pressurization cycle increased, the range of upper and lower limits come to be stabilized gradually. By graphical superposition method and bilinear pressure-accumulated volume method, reopening pressures were determined. Vertical and inclined fracture attitudes were determined by applying the directional statistics and sinusoidal curve fitting, respectively. The results of evaluation of hydrofracturing parameters showed that statistical methods could enhance the objectivity better than graphical methods.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1999년도 추계학술발표회 논문 초록집
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• pp.15-21
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• 1999