• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.293-298
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• 2005

Air-Launching is an effective method that can launch the 'Nanosat' with low launching cost. In this study, system and subsystem design of the air launching rocket for nanosats which perform a simple mission, have been performed. Foe this purpose, the WBS of the Air-launching Rocket System, and the subsystem schematics have been defined first. Based on these results, detailed configuration and DMU have been developed.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.1
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• pp.45-54
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• 2011

A program aiming at predicting dynamic characteristics of a Liquid Rocket Engine(LRE) was developed and examined to trace entire LRE operation. In the startup period, transient characteristics of the propellant flows were predicted and validated with hydraulic tests data. An arrangement of each component for the pipelines was based on an operating circuit of open cycle LRE. The flow rate ratio for the gas generator and the main chamber was determined to mimic that of real open cycle LRE. Individual component modeling at its transient was completed and was integrated into the system prediction program. Essential parameters of the component dynamic characteristics were examined in an integrated fashion.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.86.2-86.2
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• 2015

17세기 최유지가 제작한 혼천의는 수격식 동력으로 움직이는 자동 천문시계이다. 이 혼천의는 수격식 동력장치와 시간을 알려주는 시보장치, 태양과 달의 운행을 나타내는 천체운행장치로 구성되어 있다. 이 연구는 최유지 혼천의의 천체운행장치의 작동 메카니즘에 대한 것이다. 최유지 혼천의의 천체운행장치는 태양의 연주운동과 일주운동을 재현하는 태양운행장치와 달의 공전운동과 위상변화를 재현하는 달운행장치로 구성되어 있다. 이 장치들은 조선 초기의 수격식 천문시계에 설치되었던 천체운행장치보다는 발전된 양상을 보인다. 조선 초기에 실로 매어서 운행하던 태양운행장치는 차전(叉箭)과 경각(梗角), 소축(小軸)이라는 장치들이 혼천의에 추가로 설치되어 실과 함께 태양장치를 운행하였다. 또한 조선 초기에는 설치되지 않았던 달운행장치가 새롭게 설치되어 방각(方角), 차전(叉箭), 백각환에 13도 간격으로 박힌 대나무못과 실을 활용하여 달장치를 운행하게 하였다. 우리는 최유지 혼천의의 천체 운행장치 작동 메카니즘에 대하여 분석하고 개념모델을 제시했다.

• Journal of the Speleological Society of Korea
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• no.64
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• pp.61-80
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• 2004

This book deals with a .gesture of photography as a Political phenomena. In the gesture of photography, the conceptions that influences the cause and the policy of solutions that conflict the cultures, are developed. The contents of this book contains lots of items, and efforts to find the root of the digital revolution of nowadays.

• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.21-29
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• 2014

In general, a simulation project requires much time and money since we should develop a model that works similarly to the system at a level consistent with the project purposes. Therefore, more active research studies are required to reduce the time needed for the modeling process. This is achievable by minimizing the possible trial and error during the model development process through the appropriate conceptual model design and the automated generation of the simulation model. This paper presents a tool automatically generating an Arena model after developing a conceptual simulation model. Because our proposed tool is based on the popular Microsoft Excel and Visio, it is expected to be practically used at many industrial sites. Finally, we showed the effectiveness of the newly suggested tool by applying it to an imaginary simulation project.

• KDI Journal of Economic Policy
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• v.20 no.1_2
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• pp.3-77
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• 1998

경제위기 극복의 핵심과제는 '시장기구의 원활한 작동에 의존하는 경제의 틀'을 마련하는 것이며, 이를 위해서는 경제적 시장경제체제를 구축해야 한다. 이러한 견지에서 공정거래법 정책의 위상, 역할, 과제, 방향 등을 새로이 정립할 필요가 있다. 공정거래법 정책의 기초개념이 되어온 경제력(집중)과 경쟁의(불)공정성은 지나치게 포괄적이고 주관적이며 이에 대한 분석의 틀이 되는 이론체계도 없어 정책의 개념적 기반이 되기 어렵다. 공정거래법 정책은 독점력과 효율성의 개념 위에서 경제효율 증진이라는 목적을 추구해야만 정책의 일관성과 실효성을 높일 수 있다. 이는 대기업들의 독점력이 경제력집중 및 재벌구조와 형태상 제 문제의 근원(根源)이며, 독점력은 경제이론에 의해 정책방향과 기준이 제시되는 개념이기 때문이다. 공정거래법 정책은 시장구조와 형태를 실질적으로 경쟁화함으로써 경제효율을 극대화하는 데 주력해야 한다. 무엇보다도 경쟁 제한적 법령 제도 관행을 철폐하기 위한 규제개혁을 주도하고 경제구조조정과 재벌개혁의 기본원칙과 방법이 시장기능과 경쟁을 강화하는 방향으로 설정 시행되도록 하는 것이 긴요하다. 특히 대기업간 사업교환이나 인수 합병에 대하여 엄격한 경쟁정책적 검토와 규율을 적용해야 하며, 시장의 독과점화를 방지하면서 구조조정을 촉진하는 방향으로 기업결합 규제기준을 개선해나가야 할 것이다. 가격담합 등에 대한 당연위법 원칙의 확립, 입찰조작의 감시 적발체제 구축 등 카르텔 규제를 강화하고, 유통조직 활동의 효율화를 도모하면서 독점유지 강화행위를 엄격히 금지하여 다양한 유통경로와 업태가 출현 발전하도록 해야 한다. 산업조직적 조사 분석능력을 확충하여 경쟁정책적 시각에서 주요 사건을 선별 조사하고 법집행에 있어 사소(私訴)의 역할을 확대하기 위한 노력도 필요하다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.703-711
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• 2018

A preliminary design tool of a hypersonic Ludwieg tube facility which simulates real-flight environment was developed and its performance was verified by CFD(Computation Fluid Dynamics) calculations. The operating theory of Ludwieg tube was studied to develop the preliminary design tool. Using the preliminary design tool, Ludwieg tube specifications were determined to satisfy target performance. The Ludwieg tube which produces high speed flows(the Mach number ranging 4 to 10) was designed. Especially altitude simulation at Mach 4 flow could be performed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.208-211
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• 2007

Separation Devices have two functions. These two functions are to bond and to separate two bodies. This paper is about separation devices which use explosives to separate their bodies. Explosive bolt is separated with two bodies when the explosives in the body detonated. The good things of explosive bolt are that it has simple operational system and it is made of few parts. But it has side effects; fragment and pyre-shock. To avoid these side effects gas expansion separation(GES) bolt and pressure cartridge actuation separation(PAS) devices are invented. These use pressure to separate their bodies. The pressure is generated when explosives are burned. But the sizes of PAS devices are bigger than explosive bolts. And GES bolt has a mechanically lower bonding ability than that of explosive bolt. When you design separation devices, it is recommended to know operational system and characteristics of separation devices, to design best one.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.475-482
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• 2014

This paper presents the results of an experimental feasibility study on low-temperature differential Stirling engines with water spray heat transfer. The water spray enhances the efficiency of the heat transfer from heat sources to the engine and reduces the performance degeneration due to the dead volumes of conventional heat exchangers. A test Stirling engine was developed and an experiment was conducted to determine the characteristics for the initial start-up, steady-state operation, and power output for various flow rates and temperatures of hot supply water. The test results showed that larger flow rates led to reductions in the minimum working temperature of the hot water at start-up. During a series of steady-state operations, higher flow rates and temperatures increased the working speed. Furthermore, the work per cycle and power output were also increased. Eventually, the test Stirling engine had a power level of 0.05 W. Based on this, further research will be conducted to obtain a higher power output and investigate various applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.681-688
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• 2018

As environmental regulations have been strengthened and high fuel efficiency has been in demand in recent years, the number of ships using natural gas as a fuel is increasing. The demand for ships using LPG or methanol, which are emerging as eco-friendly vessel fuels, is also increasing. In this perspective, ME-LGI engines using LPG or methanol as a fuel have attracted considerable attention. Ships equipped with an ME-LGI engine are required to check the reliability of the fuel injection valve during shipping. This means that the development of a fuel injection valve tester is essential for the commercialization of ME-LGI engine. This study conducted the conceptual design of a fuel injection valve tester for ME-LGI engines using a system engineering process in the order of requirements analysis, functional analysis, and design synthesis. In the requirement analysis stage, the operating process of fuel injection valve was analyzed, and the necessity of checking the sealing oil leakage was then derived. In the functional analysis stage, the functions and flow of them were defined at each functional level. In the design synthesis stage, the equipment for each function was set and the process block diagram based on it was derived. In addition, preliminary risk analysis was performed as a part of system analysis and control, and safety measures were added to the conceptual design. This study is expected to be a good reference material for the concept design of other systems in the future because it shows the application process of a system engineering process to the conceptual design in detail.