• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.503-516
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• 2021

Autonomous fire detection and suppression system requires advanced technology for complex detection technology and injection/control technology for accurate hitting by fire location. Also, foam spraying should be included to respond to oil fires. However, when a single spray monitor is used in common, water and foam spray properties appear different, so for accurate fire suppression, research on the spray trajectory and distance will be required. In this study, experimental studies and numerical analysis studies were combined to analyze the foam spray characteristics through the spray monitor developed for the establishment of an autonomous fire extinguishing system. For flow analysis of foam injection, modeling was performed using OpenFOAM analysis software, and the commonly used foaming agent (Aqueous Film-Forming Foam) was applied for foam properties. The injection distance analysis was performed according to the injection pressure and the injection angle according to the form of the foam, and at the same time, the results were verified and presented through the injection experiment.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.426-429
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• 2011

산불 발생 시 진화를 위해 사용되는 주력 지상 진화장비 중 동력펌프 2종과 진화 차량을 대상으로 수원지로부터 발화 지점까지 진화거리에 따른 주요 성능을 측정하였다. 성능 측정은 분당 토출량, 토출 최대압력, 수평 분사거리, 수직 분사거리의 4개 항목이었으며, 노즐의 종류에 따른 영향을 동시에 고려하였다. 산불 진화 시 적정 거리를 측정한 결과 소형펌프의 경우 600m, 중형펌프의 경우 800~1000m 정도인 것으로 나타났다. 또한 분당 토출량은 3가지 펌프 모두 50m에서 1000m로 연결할 경우 52~62% 감소가 일어나며, 최대 토출압력은 26~30% 상승되어 부하 발생시 고압호스의 파손 우려도 있는 것을 알 수 있었다. 실험을 통해 소형펌프의 경우는 주 산불진화에 적합하지 않으며, 중형펌프의 경우 고압호스의 성능에 따라서 1000m이상의 거리에서도 사용이 가능할 것으로 사료된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.64-71
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• 2005

To achieve efficient supersonic combustion within a manageable length, a successful fuel injection scheme must provide rapid mixing between fuel and airstream. In former days, various injection concepts have been investigated. Cavity flow is the open type, that is, length-to-depth ratio L/D=4.8, aft ramp angle is $22.5^{\circ}$. An experimental study on a transverse cross jet injection into a Mach 1.92 supersonic main stream which flows over a cavity was carried out to investigate the effect of the momentum flux ratio(J), the jet interaction characteristics, and the pressure distribution in the combustor and using the primary diagnostics : schlieren visualization and wall static pressure measurements. Fuel penetration height and jet interaction characteristics depend strongly on the momentum flux ratio.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.59-63
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• 2006

A direct photograph measurement technique was used to determine the spatial distribution of the spray droplet diameter in subsonic crossflow and it also obtain that SMD distribution by using PLLIF technique. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of this research are getting a droplet distribution and drop size measurement of normal flow and compare with the other flow effects. Although the study showed visually that drop size were spatially dependent of Air-stream velocity, fuel injection velocity, and normalized distance from the injector exit length.(x/d, y/d) There are also difference characteristics between cavitation, hydraulic flip and the normal flow.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.319-322
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• 2006

Rapid mixing of air-fuel (<1 ms) is needed to accomplish supersonic combustion. In this experiment, helium was injected laterally in to the Mach 1.92 air flow. 2 kinds of model, flat plate/cavity, were used in this experiment and images were taken by schlieren visualization. Pressure was affected by shock structure in the supersonic duct, and penetration height was increased by increasing J. Penetration height was higher in the cavity model than flat plate model.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.401-404
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• 2010

A spray-type cleaning agent in utilizing dust-remover on PCB was chosen to study. In cleaning of electronic and semiconductor equipment, a substrate(IPC-A-36) was used to test the jet forces of the agent. And according to the jet forces time of the cleaning agent, the corresponding moving distances were compared with the spray times, and for the pollutants of iron powder and dust, the cleaning efficiency was tested with the IPC-A-36 by a weight method. The moving distance increased with the spray cleaning time longer. For a spray cleaning time of 3sec, the cleaning efficiency decreased with the amount of dust and the iron powder. It was also observed that the dust was remarkably removed, compared to the iron powder.

• Journal of Power System Engineering
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• v.14 no.2
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• pp.16-21
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• 2010

분사된 연료의 미립화(atomization), 증발(evaporation), 그리고 혼합기형성과정(mixture formation process)이 디젤엔진의 착화 및 연소특성에 영향을 미치기 때문에, 디젤엔진 내에 분사된 연료의 구조해석으로부터 일련의 과정, 즉 고압분사, 분열(breakup), 미립화, 그리고 주위기체의 난류 도입(entrainment)에 관한 연구$^{1-3)}$는 꾸준히 행해져왔다. 본 연구는 증발디젤분무의 구조해석으로부터 디젤충돌분무의 혼합기형성과정을 조사한다. 주위기체의 밀도는 실험변수로서 선택하였고, $5.0kg/m^3$에서 $12.3kg/m^3$까지 변화시켰다. 그리고 소형고속디젤엔진에 있어서 연료분사초기의 상태의 고온 고압 설정이 가능한 정적용기를 사용했다. 주위 온도와 연료분사압력은 각각 700K 및 72MPa로 일정하게 유지했다. 충동증발분무의 액상과 기상의 이미지는 엑시플렉스형광법으로 동시 계측하였다. 실험결과로서 주위기체의 밀도가 높을수록 충돌분무의 선단도 달거리가 주위기체의 항력으로 인하여 감소하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.72-75
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• 2003

In this research, we focused on the effects of the orifice internal flow such as cavitation and hydraulic flip. The breakup characteristics such as the breakup length and trajectory were measured by changing the orifice diameter (d), the orifice length/orifice diameter (L/d), the injection pressure and the shapes (sharp and round) of orifice entrance to provide a lot of conditions of the orifice internal flow. It is found that cavitation bubbles that occur inside the sharp-edged orifice make the liquid jet ejecting from the orifice turbulent. In the orifices (L/d = 5), the hydraulic flip phenomenon is shown when the injection pressure is high. In case cavitation occurs it breaks up more earlier than that in case of non-cavitation. In case hydraulic flip occurs, since the area of the liquid jet becomes small, the breakup length is also small as that in case of cavitation. But the liquid column trajectories have a similar tendency irrespective of cavitation.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1190-1192
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• 2008

증기 분사식 가습기의 소비전력량을 줄이기 위하여 전극의 재질 및 전극간 거리를 분석하여 단위 전력량당 증기발생량을 향상하여 에너지 소비량을 줄이고자 한다. 이를 위하여 물의 전도도, 전극간 저항, 전극 크기 및 전극간 거리 등의 변수가 있으나 우선 전극간의 거리를 변화시켜 이에 대한 상태변화를 살펴보았다. 본 실험을 위하여 극간 거리를 40, 50, 60, 70, 80, 90mm 순서로 가습기 본체를 제작하여 실험하였다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.31-33
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• 2003