• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.196-200
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• 2005

A theoretical model for the calculation of chemical equilibrium composition of propellant combustion product is briefly presented for the performance analysis of monopropellant hydrazine rocket engine. Analysis result is compared to that of test and evaluation of 1-lbf class thruster and is scrutinized primarily from the view point of ammonia dissociation fraction. Chemical equilibrium composition and average molecular weight is additionally depicted according to the variation of propellant inlet pressures and the varying nozzle area ratio. The theoretical analysis is tried as a way of derivation of design parameters for mid- and large-thrust class of monopropellant rocket engines.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6324-6329
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• 2013

The aim of this study was to prepare and evaluate tablets containing liquid choline alphoscerate, which is capable of being formulated as a solid dosage form by the adsorption of magnesium aluminum silicate. The tablets were prepared with various absorbent to choine alphoscerate ratios. The physical properties and the dissolution rate were investigated. Considering the tabletting and dissolution rate, the formula scontaining 50-75% absorbent were adequate in the tested formulations. The 62.5% absorbent formula showed superior results with the tests of hardness, friability, disintegration time, and the ratio of dissolution area under the curve. Overall, magnesium aluminum silicate can be an alternative additive to a liquid drug.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.438-449
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• 2004

With the growing deployment of network and internet, the importance of security is also increased. But, recent intrusion detection systems which have an important position in security countermeasure can't provide proper analysis and effective defence mechanism. Instead, they have overwhelmed human operator by large volume of intrusion detection alerts. In this paper, we propose an efficient alert analysis system that can produce high level information by analyzing and processing the large volume of alerts and can detect large-scale attacks such as DDoS in early stage. And we have measured processing rate of each elementary module and carried out a scenario-based test in order to analyzing efficiency of our proposed system.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.835-843
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• 2009

Recently the more stable roadbed is required due to the high speed and design load. Therefore the reinforced roadbed was introduced as the solution. But the thickness and stiffness of reinforced roadbed in design code is being conservatively assessed by the foreign code without considering the domestic construction condition. In this paper, adequate Young's modulus, drain capacity, freezing depth, economical efficiency, bearing capacity, construction condition and 3-D finite element method were employed to determine the proper thickness of reinforced roadbed at the embankment section.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.417-420
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• 2009

The purpose of the present study is to evaluate high temperature fracture toughness through the experimental and analytical method. The analysis method is proposed to simulate the fracture toughness of high temperatures. Load-COD curves of compact test specimen acquired by finite element method analysis using hypo elastic model are simulated to determine the crack initiation load on high temperatures. The results of experimental work are in accord with analysis in thermal shock test.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.553-556
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• 2009

In this study, ignition tests of a gas turbine combustor were performed to evaluate an ignition loop at low temperature condition. An experimental setup was constructed to simulate low temperature condition with a heat exchanger using dry ice as a coolant. Various low temperature conditions could be created by controlling the amount of air though the heat exchanger. The results showed that ignition limit decreased with air temperature.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.81-84
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• 2003

부분방전시험은 고전압 고정자 권선의 절연상태를 검사, 평가 할 수 있는 중요한 수단이다. 전동기와 발전기에서 일어나는 절연 악화의 징후로써 부분방전이 발생되며 이러한 부분방전 신호를 검출하기 위한 센서로 SSC(Stator Slot Couple)를 사용한다. 하지만 현재 사용되고 있는 대부분의 SSC의 경우 설계에 있어 특성 임피던스가 실제구조에서 정확히 고려되지 않는 경향이 있다. 실제로 고정자 슬롯에 부착된 마이크로스트립 센서의 특성 임피던스는 정확히 50옴으로 정합 되지 않으며 이것은 센서의 성능에 중요한 영향을 미치게 된다. 그러므로 본 논문에서는 부분방전 센서의 성능을 개선시키기 위해 결합 전송선로(Coupled transmission line)를 이용한 임피던스 정합회로를 제안하고자 한다. 제안된 센서의 성능을 입증하기 위하여 고정자 슬롯에 설치된 기존의 SSC와 임피던스 정합회로를 부착한 센서를 시뮬레이션 한 후 비교 분석하였다. 결과적으로 제안된 정합 회로는 광대역 임피던스 정합 특성을 가지며 임피던스 부정합때문에 일어나는 기존 SSC의 성능 악화를 개선할 수 있었다.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.13-20
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• 2014

It is necessary to design a compressor with high pressure ratio that satisfies the IMO(international maritime organization) NOx emission regulation for the marine diesel engine. Impeller was designed using the modified slip factor with the flow coefficient. The main purpose of this study is to investigate the sensitivity of the compressor performance by the vaned diffuser geometries. The first vaned diffuser type was based on a NACA airfoil, the second was channel diffuser, and the third was conformally transformated configuration of a NACA65(4A10)06 airfoil. The sensitivity of the performance was calculated using a commercial CFD program for three different diffuser geometries. The channel diffuser showed the wide range of operation and higher pressure characteristics, comparing with the others. This is attributed to the flow stability at diffuser. Combined with this results with impeller design, the optimized compressor was designed and verified by the test results.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.3
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• pp.1-7
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• 2002

During the preliminary design phase of aircraft development, it is necessary to evaluate many potential engine/airframe combinations to determine the best solution to given set of mission requirements and it is very important to establish a methodology to calculate precisely engine installed performance. It was carried out to calculate turbofan engine installed performance of a supersonic aircraft for a given engine/aircraft configuration. Thus "Thrust minus drag accounting system" was introduced to identify and calculate the elements of installed thrust or installed propulsive force by using the database based on wind tunnel test data. This paper describes the calculated results of installed thrust of turbofan engine for a supersonic aircraft. aircraft.

• Journal of the Korean Institute of Gas
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• v.4 no.4 s.12
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• pp.6-12
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• 2000

We have developed a new split tee which can be used to effectively branch into a main gas steel pipelines without losing any gas pressure or having to shut down a line. The split tee has been designed considering the locations of branch connection to the pipelines. Therefore, we could keep the depth of buried pipelines which used to be the problem of the conventional split tees. Test results of the developed split tee showed that the performance of the tightness, hydraulic strength, sealing, welding, bending, and compatibility were excellent. The application of the split tee can provide the advantage of eliminating cost and time, and easy field pipeline coatings.