• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.25-28
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• 2010

The Cold flow and ignition tests have been performed for a technology demonstration model of 75-tonf liquid rocket engine thrust chamber which was designed and manufactured on the basis of the previous development experience of a 30-tonf liquid rocket engine thrust chamber. The hydrodynamic characteristics of the facility supply pipelines and the filling time of the cooling kerosene were obtained through the cold flow tests. The ignition cyclogram was determinded using the results and the ignition test was successfully carried out. The acquired data and test technique of present ignition test will be used in hot firing tests.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.83-90
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• 2020

This study conducted a risk assessment using the HyKoRAM program created by international joint research. Risk assessment was conducted based on accident scenarios and worst-case scenarios that could occur in the facility, reflecting design specifications of major facilities and components such as compressors, storage tanks, and hydrogen pipes in the hydrogen charging station, and environmental conditions around the demonstration complex. By identifying potential risks of hydrogen charging stations, we are going to derive the worst leakage, fire, explosion, and accident scenarios that can occur in hydrogen storage tanks, treatment facilities, storage facilities, and analyze the possibility of accidents and the effects of damage on human bodies and surrounding facilities to review safety.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.516-525
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• 2000

Recently, the demand for pollution-free demolition work of old reinforced concrete and steel structure has rapidly increased as the redevelopment of urban area has been accelerated. This study deals with linear shape charges for explosive jet cutting on steel structure. We have tested material and shape of steel structure, characteristics of thickness and strength, shape of linear shape charges, type of shape charges, cumulative charges, type of liner, stand-off distance, detonation method. effect of sound and vibration by air blast in explosive jet cutting method. So, We developed linear shape charges in order to take advantage of optimum explosive jet cutting condition. Shape charges were made of PETN explosives. We obtained the experimental formula to decide the amount of explosive needed for thickness of steel structure plate. There are prospects for application of the explosion curving technology under the open space conditions for dismantling the steel structure and steel bridge, scrapped old boats, which are going out of service.

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.74-81
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• 2020

In general, when manufacturing a semiconductor, a number of hazardous and dangerous substances such as flammability, toxic, and corrosiveness are used. In particular, semiconductors are manufactured using specialty gas in processes such as CVD and etching. The specialty gas is filled in a container in the state of compressed or liquefied gas, and a gas cylinder cabinet is used as a facility for supplying this specialty gas to the semiconductor manufacturing process. When a accident occurs in the gas supply system, gas is released through a pressure release device installed in the gas cylinder to secure the safety of the supply system. In this case, the gas released inside the gas cabinet, there is a risk of leaking to the outside. After that, by analyzing the gas flow in the gas cabinet, it is intended to identify the risk associated with leak and to provide measures to prevent accidents.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.11a
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• pp.138-138
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• 2000

국내의 백상지 공정은 공정에 투입되는 청수의 양을 줄이면서 동시에 폐수 배출 양을 감 소시키기 위해 많은 노력을 하고 있다. 공정으로 유입되는 청수의 양과 처리된 폐수의 양을 줄이기 위한 방법으로 PDFCpolydisk filter)를 도입하여 백수를 여과하여 showertf sealing 에 재사용하고 있으며 공정수 재활용에 따른 유기 물질과 무기물질의 계 내로의 축적을 방 지하기 위한 효과적인 폐수 처리방법을 모색하고 있다. 일반적으로 청수를 백수로 대체할 경우 공정 백수 내에 TDSCtotal dissolved solid), T TSSCtotal suspended solid), CODCchemical oxygen demand), 전기 전도도와 칼숨 경 도 등이 증가되며 음이온성 저해 물질Canionic trash)이 증가하여 보류 및 지력증강용 첨가제의 효율 을 떨어뜨릴 뿐만 아니라 마모, 슬라엄, 펠트 막힘 등의 문제를 유발하게 된다고 알려져 있다. 청수를 백수로 대체함에 따라 생기는 이러한 문제를 해결하면서 효율적인 청수 절약 방안 을 세우기 위해서는 무엇보다도 문제를 유발하는 원인 물질의 축적 양을 예측하는 것이 중 요하다고 판단된다. 본 연구는 백상지 공정의 폐쇄화 수준이 높아짐에 따른 공정 백수 내의 유기물질의 축적 현상을 분석하는 것올 목적으로 하였다. 이를 위해 산화전분을 유기물질의 대표하는 물질로 설정하였다. 이는 백상파지와 함께 초지계 내로 유업되는 산화전분은 파지의 4%를 차지할 정도로 유입량이 많을 뿐만 아니라 음이온성을 띄고 있어서 지료에 홉착율이 낮고 양이온성 고분자의 효율을 저해하며 슬라임의 원인이 되기도 하는 물질이기 때문이다. 산화전분의 축적 현상을 분석하기 위하여 pilot 설비 상세 설계도를 참고하여 하루 생산량 이 16 T/D이고 백상파지만이 파지로 유입되는 백상지 생산 공정을 모델로하였으며, 산화전 분의 홉착과 용출 모델을 만들어 상용 시율레이터를 이용하여 시율레이션 프로그램을 작성 하였다. 시률레이션 프로그램에서는 장섬유 미세섬유, 충전제를 지료 구성 성분으로 설정하였고 O Orccotoma 등이 사용한 일과 보류도 모델을 응용하여 보류도 모델올 만들었다. 산화전분은 백상파지에 포함된 형태로만 초지계 내로 유입되며 백상파지가 해리되는 과정에서 완전히 백수에 용출되었다가 지료 구성 성분에 홉착되는 것으로 가정하였다. 지료 홉착된 산화전분 의 양은 용존 산화전분 총량에 비례하는 것으로 가정하였으며, 이 때 이 비례상수를 전분 홉착율이라 정의하였다. 시율레이션 결과, 공정 폐쇄화가 진행됨에 따라 백수 내의 산화 전분 농도는 증가하게 되 며, 폐쇄화 수준이 높아질수록 백수 내 전분 농도의 증가량은 더 높아졌다. 백수 내의 전분 농도의 증가량은 백상파지 첨가량이 증가할수록, 표면 사이징 양이 증가할수록 커졌다.

• Composites Research
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• v.27 no.6
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• pp.254-259
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• 2014

In this study, a device and pressure press process that is able to substitute autoclave process is developed. This process complements disadvantages of autoclave process which are long process-time and high production cost. The developed device provides air pressure as well as the vacuum which are greatest feature of autoclave process. The device is sealed using hydraulic pressure to keep the air pressure inside the mold. The transfer of the heat is designed to be direct. The heating and pressure charging time are decreased by reducing the interior space. Tooling cost is reduced dramatically compared to autoclave process. Spring-back phenomenon is measured and compared. The temperatures of several parts of the mold during molding are measured. The fiber volume fraction of the parts molded by autoclave process and by the developed process are compared.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.843-848
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• 2013

As the LNG demands are growing, the constructions of LNG FPSO (Floating Production Storage and Off-loading) and LNG carriers have been constantly increased, and the various design of storage tank has been tried. This paper propose that the material of inner storage tanks is made of 5~9% Ni steel plate and perlite powder insulation instead of urethane foam block. It needs essentially to obtain the proper design specifications that are the pressure of perlite, the characteristics of resilient blanket as the pressure absorber, optimum thickness of blanket and design pressure of tank wall, etc. to enable the perlite insulation system to LNG carrier, The results show that the design thickness of blanket should be between 1/4 to 1/3 of insulation width and the optimum rate becomes 30%, and the design pressure be applied below 1,500 Pa with blanket thickness.

• Journal of the Korean Society for Railway
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• v.18 no.4
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• pp.301-308
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• 2015

To reduce the weight of a railroad vehicle, a bogie frame skin is considered for manufacture using an RTM process and composite material. Compared to other processes, RTM has merits in that it demands only simple manufacturing facilities and can produce a large and complex structure in a short cycle time. On the other hand, it is important to determine the proper number and locations of gates and vents to prevent void formation inside a structure. In this study, we numerically predicted the flow pattern in a bogie frame skin during the RTM process by distinguishing the permeability of a fiber mat as isotropic or anisotropic. Using the results, we analyzed the RTM process conditions of the bogie frame to predict skin void formation, mold filling time, and optimum location of vents depending on the permeability conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4178-4184
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• 2013

Nanoimprint lithography (NIL) is an emerging technology enabling cost-effective and high-throughput nanofabrication. Recently, the major trends of NIL are high throughput and large area patterning. UV curable type NIL (UV NIL) can be performed at room temperature and low pressure. And one advantage of UV NIL is that it does not need vacuum, which greatly simplifies tool construction, so that vacuum oprated high-precision stages and a large vacuum chamber are no longer needed. However, one key issue in non-vacuum environment is air bubble formation problem. Namely, can the air bubbles be completely removed from the resist. In this paper, the air bubbles formation by the method of droplet application in UV NIL with non-vacuum environment are experimentally studied. The effects of the volume of droplet and the number of dispensing points on air bubble formation are investigated.

• Journal of Korean Society of Disaster and Security
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• v.16 no.1
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• pp.71-80
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• 2023

Fuel cells are low-carbon power sources that can expand distributed energy system and electric vehicle charging infrastructure when installing fuel cells in gas stations. In order to ensure safety for fuel cells in gas stations, quantitative risk assessments were conducted after deriving accident scenarios based on accident data of domestic and foreign gas stations and fuel cells. It calculates the expected extent of damage from fire and explosion that can occur in reality, not the worst accident scenario, and analyzes the damage impact. The separation distance of more than 9.0 m from a dispenser, 15.5 m from a car under refueling, 4.1 m from the ventilation pipe, 1.1 m from the gas adjustment device prevent the severe damage caused by the expected accident. This study result can be used to deploy fuel cells in gas stations and establish safety measures.