• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.313-317
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• 1996

This work deals with description of gas purifing system to product high pure helium gas using low temperature absorption. The system controls temperature of heaters, open/close of solenoid valves and levels of liquid nitrogen to purify a raw gas and continuously products purified gas with perfoming alternatively purification and regeneration. We develop the monitoring and control program to monitor the gas purification process on real-time and control the process time with checking the impurities in purified gas. From the result of system operation, the developed monitoring and control system continuously products high pure helium gas with reducing impurities in raw gas to permitted limits(less than 0.01 ~ 0.05 ppm)

• 한국가스학회:학술대회논문집
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• 한국가스학회 1998년도 추계학술발표회 논문집
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• pp.241-246
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• 1998

This paper considers the applicability of a pseudosteady-state approach to the long-time behavior of real gas flow in a closed reservoir. The method involves a combination of a linearized gas diffusivity equation using a normalized pseudotime and a material balance equation. Comparison with a commercial reservoir simulator showed that highly accurate values of pseudopressure drawdown and well pressure are obtained by the pseudosteady-state approach with much less computational effort.

• 한국소음진동공학회논문집
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• 제18권7호
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• pp.693-700
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• 2008

High-Pressure gas Pipeline which is buried in underground has the Possibility that will be exposed to unexpected dangerous impact of construction equipment. To protect from this kind of danger, the real-time health monitoring system of the high-pressure gas pipeline is necessary. First of all, to make the real-time health monitoring system clearly, the acoustic wave propagation characteristics which are made from various construction equipment impacts must be identified. In link of technical development that prevents the damage of high-pressure gas pipeline, this paper gives FEM(finite element method) and BEM(boundary element method) solutions to identify the acoustic wave propagation characteristic of the various impact input signals which consist of Direc delta function and convolution signal of 45 Hz square signal and random signal.

• 한국안전학회지
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• 제25권6호
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• pp.98-102
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• 2010

LPG (Liquefied Petroleum Gas) vehicles in metropolitan area are being applied to improve air quality and have been proven effective for the reduction of air pollutant. In addition, the demand of gas as an eco-friendly energy source has being increased. With the LPG filling station is also increasing every year. These gas stations are required to install the securest storage tank because of possibility of causing huge loss of life and property. Therefore, in this paper, underground containment type is proposed as installation of the LPG storage tank using Taguchi method, which is considered to be more safe, economical, efficient, easy checking and simple construction method than any other. If leakage, economics, real estate utilization rate, safety, easy to check, simple construct about above ground, buried underground and underground containment storage tank are analyzed by Taguchi method, real estate utilization rate, economic and safety in turn are improved. Therefore, the underground containment storage tank is a optimal installation technology.

• 센서학회지
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• 제17권6호
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• pp.406-413
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• 2008

We have been implemented simple statistical pattern recognition methods for harmful gases classification using gas sensors array fabricated by MEMS (Micro Electro Mechanical System) technology. The performance of pattern recognition method as a gas classifier is highly dependent on the choice of pre-processing techniques for sensor and sensors array signals and optimal classification algorithms among the various classification techniques. We carried out pre-processing for each sensor's signal as well as sensors array signals to extract features for each gas. We adapted simple statistical pattern recognition algorithms, which were PCA (Principal Component Analysis) for visualization of patterns clustering and MLR (Multi-Linear Regression) for real-time system implementation, to classify harmful gases. Experimental results of adapted pattern recognition methods with pre-processing techniques have been shown good clustering performance and expected easy implementation for real-time sensing system.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.264-269
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• 2010

This paper presents the analysis of the dielectric characteristics of a hot $SF_6$ gas in a gas circuit breaker. Hot gas flow is analyzed using the FVFLIC method considering the moving boundary, material properties of real $SF_6$ gas, and arc plasma. In the arc model, the re-absorption of the emitted radiation is approximated with the boundary source layer where the re-absorbed radiation energy is input as an energy source term in the energy conservation equation. The breakdown criterion of a hot gas is predicted using the critical electric field as a function of temperature and pressure. To validate the simulation method, breakdown voltage for a 145kV 40kA circuit breaker was measured for various conditions. Consistent results between the simulation and experiment were confirmed.

• 자원ㆍ환경경제연구
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• 제18권2호
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• pp.217-239
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• 2009

최근 화석에너지가 가진 환경 및 고갈 문제들을 경감시킬 수 있는 에너지 자원으로서 가스하이드레이트가 주목을 받으며, 우리나라에서는 2005년부터 2014년까지 10개년 계획 하에 가스하이드레이트 개발사업을 진행하고 있다. 가스하이드레이트 개발사업은 수력원자력을 제외하면 사용 에너지의 대부분을 수입에 의존하고 있는 우리나라의 경제사회에 미치는 파급효과가 상당히 클 것으로 예상되지만, 성공여부는 불확실하다. 그러므로 사업의 가치평가를 사전에 수행하여 타당성을 제고하고, 효과적인 수행 전략을 제시하는 것이 매우 중요하다고 할 수 있다. 본 논문에서는 가스하이드레이트 개발사업의 가치평가를 수행하기 위해 퍼지위험분석을 실물옵션모형에 적용시킴으로써 기존의 방법론에서 측정하지 않았던 정보들을 포함시키고, 가치평가 결과에 나타나는 편의나 오류를 감소시키고자 하였다. 퍼지위험분석을 적용한 실물옵션모형은 무형요인들에 대한 판단의 모호성과 부정확성을 적당한 언어척도로 모형화함으로써 이 요인들을 명시적으로 평가하고, 재무적 성과측정치와 함께 통합될 수 있도록 해주는 장점을 가진다. 이는 의사결정자의 직관에 의해서도 부분적으로 평가가 가능하겠으나, 직관에 따른 판단은 여러 가지 요인들을 동시에 고려하여 일관성 있는 평가를 내리는 데 한계가 있을 것이다. 하지만 퍼지위험분석을 적용하면 복합적인 여러 가지 속성의 의사결정 문제가 단순화된 부분적 문제들로 분해되어 분석이 가능하게 된다. 고유가의 지속과 함께 청정에너지에 대한 시대적 요구로 인하여 에너지 자원 또는 기술 개발 사업의 필요성이 더욱더 증대되고 있다. 이 가운데 본 연구의 결과가 가스하이드레이트 개발 사업뿐 아니라, 향후 에너지 산업과 관련된 정책의사결정에 하나의 가이드라인을 제시할 수 있으리라 기대된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.11-17
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• 2009

가스발생기 사이클의 추력 30톤급 액체로켓엔진용 터보펌프에 대하여 실매질 고온 시험이 이루어졌다. 산화제펌프와 연료펌프에는 각각 액체산소, 케로신이 공급되고 터빈에는 고온의 가스가 공급되며이 가스는 펌프로부터 배출되는 추진제의 일부를 가스발생기에서 연소시켜 생성된다. 터보펌프는 시험중에 설계점과 탈설계점의 전 영역에서 안정적으로 작동하였고 성능 요구 조건을 만족시켰다. 본 논문에서는 여러 차례의 시험 중에서 단일 운전으로 세 운용점에서 총 120초간 작동된 경우에 대하여 터보펌프에 관심을 두고 시험결과를 소개한다. 펌프와 터빈의 성능 특성 관점에서 터보펌프 조립체의 실매질 고온 시험 성능시험 결과와 터보펌프 구성품의 상사 성능 시험 결과가 양호하게 일치하였다.

• 한국분무공학회지
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• 제1권1호
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• pp.35-43
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• 1996

A vaporization model for single component fuel droplet has been developed for applying to sub- and supercritical conditions. This model can account for transient liquid heat ins and circulation effect inside the droplet, forced and natural convection, Stefan flow effect, real gas effect and ambient gas solubility into the liquid droplet in high-pressure conditions. Thermodynamic and transport properties are calculated as functions of temperature and pressure in both phases. Numerical calculations are carried out for several validation cases with the detailed experimental data. Numerical results confirm that this supercritical vaporization model is applicable to the high-pressure conditions encountered in the combustion processes of diesel engine.

• Journal of Advanced Marine Engineering and Technology
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• 제29권1호
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• pp.116-123
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• 2005

The PID controllers have been widely accepted in many industrial systems due to their robust performance in a wide range of operating conditions and their functional simplicity To implement a PID controller, its three parameters must be determined for the given plant. Conventional tuning methods are mainly based on experience and experiment and are lack of systematic procedure Recently. to overcome drawbacks of conventional tuning methods, genetic algorithms have been used, In this paper a real-coded genetic algorithm is employed to search for the optimal parameters of the PID controller for speed control of marine gas turbine engines. Simulation results show the effectiveness of the proposed scheme.