• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.919-920
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• 2009

액화 천연 가스 플랜트 시뮬레이터는 막대한 자본 투자가 필요한 대형 시스템 설계 및 건설 단계에서 사전에 설계 오류 검출 및 시스템 검증을 함으로써 많은 비용을 절약해줄 수 있는 중요한 시스템이다. 이 연구에서는 플랜트, 시뮬레이터, 운전원 훈련 시스템 및 제어시스템을 운전하는 과정에서 발생하는 정보를 효과적으로 처리하기 위해서 구축되는 정보 처리 시스템의 기본 설계에 관한 내용을 소개한다. 전체 시스템은 물리적 플랜트와 가상 플랜트로 나눌 수 있고 가상 플랜트는 시뮬레이터와 운전원 훈련 시스템으로 구현되며, 제어 시스템은 PLC로 구현하고 Modubus 프로토콜과 OPC 서버를 통해 데이터 처리가 가능하다. 플랜트로부터 생성되는 데이터 처리에서는 실시간 데이터 처리 속도가 중요하므로 실시간 데이터베이스를 도입하였다. 실제 플랜트 데이터와 시뮬레이터 데이터는 상호 교환이 가능하도록 구성하였다. 본 시스템 설계는 기본 설계 단계이므로 향후 LNG 플랜트에 적용하기 위해서는 상세 설계가 필요하다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.583-589
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• 2016

Volatile organic compounds(VOCs) are regarded as a harmful cause substance not only causing air pollutions but also causing global warming phenomenon. For this reason, VOCs are managed politically to reduce emissions by each country. In particular, the vapor from the gas station contains VOCs which is harmful to the human body such as carcinogens benzene and pollute the atmosphere, the Ministry of Environment defined every gas station must install vapor recovery equipment to recover volatile organic compounds. Recently, there are many accidents caused by existing vapor treatment methods, the liquefaction recovery technology is getting the spotlight to cool the vapor at the field. However, because the liquefaction recovery technology have risks of fire or explosion in accordance with temperature, the real time monitoring is critical factor. In this paper, we implement an Android-based monitoring application for liquified vapor recovery device which attached sensor module for temperature and power to monitoring real time information.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1591-1602
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• 1996

In operating the underwater engines such as encountered in exploring submarines, the dumping of the exhaust gas out of the engine requires a large portion of the total power, frequently amounting to 25-30% of the power generated. This unfavorable circumstance can be cured by liquefying the exhaust gas and storing it. In the present study, two liquefaction systems were simulated to enhance the overall efficiency; one is a closed cycle diesel engine and the other is a closed cycle LNG engine. The liquefied natural gas (LNG) is chosen as a fuel, not only because its use is economical but also because its cold energy can be utilized within the liquefaction system. Since a mixture of oxygen and carbon dioxide is used as an oxidizer, liquefying carbon dioxide is of major concern in this study. For further improving this system, the intercooling of the compressor is devised. The necessary power consumed for the liquefying system is examined in terms of the related properties such as pressure and temperature of the carbon dioxide vessel as a function of the amount of the exhaust gas which enters the compressor. The present study was successful to show that much gain in the power and reduction of the vessel pressure could be achieved in the case of the closed cycle LNG engine. The compression power of exhaust gas were observed remarkably lower, typically only 6.3% for the closed cycle diesel engine and 3.4% for the closed cycle LNG engine respectively, out of net engine power. For practicality, a design -purpose map of the operating parameters of the liquefaction systems was also presented.

• Journal of the Korean Institute of Gas
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• v.23 no.4
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• pp.19-27
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• 2019

The consumption of liquefied natural gas (LNG) has increased annually due to the strengthening of international environmental regulations. In order to produce stable and efficient LNG, it is essential to divide the global (overall) operating condition and construct a quick and accurate monitoring system for each operation condition. In this study, multi-mode monitoring system is proposed to the LNG plant fractionation process. First, global normal operation data is divided to local (subdivide) normal operation data using global principal component analysis (PCA) and k-means clustering method. And then, the data to be analyzed were matched with the local normal mode. Finally, it is determined the state of process abnormality through the local PCA. The proposed method is applied to 45 fault case and it proved to be more than 5~10% efficient compared to the global PCA and univariate monitoring.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.154-155
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• 2013

본 논문에서는 소형이고 활어차용 고순도 산소공급장치를 개발하는 것으로 별도의 충전된 산소통을 구비하지 않고 공기에서 산소를 생산하여 활어차의 활어 저장 수조에 고순도 산소를 공급함으로써 신선한 활어의 상태를 유지하는 시스템이다. 현재는 활어차에 액화산소, 기체산소통을 구비하여 활어 저장 수조에 산소를 공급하는 방식으로 물류비용 및 선도유지와 위생처리 문제 등이 어렵다. 따라서, 본 시스템에서는 활어가 최적의 신선도를 유지할 수 있도록 영구적 산소를 생산하기 위한 운반차 전용 산소발생모듈을 개발하여 활어차 차주의 채산성 개선을 위해 액화대비 저렴한 산소 생산이 가능하도록 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1218-1224
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• 2017

With the increasing risk in building liquefied natural gas carriers (LNGC), pre-simulation of various scenarios is required for system integration and safe operation. In particular, the power management system (PMS) is an important part of the LNGC; it works in tight integration with the power control systems to achieve the desired performance and safety. To verify and improve unpredicted errors, we implemented a simulation model of power generation and consumption for testing PMS based on software-in-the-loop (SIL) method. To control and verify the PMS, numeric and physical simulation modeling was undertaken utilizing MATLAB/Simulink. In addition, the simulation model was verified with a load sharing test scenario for a sea trial. This simulation allows shipbuilders to participate in new value-added markets such as commissioning, installation, operation, and maintenance.

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.55-62
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• 2015

The liquefaction to produce LNG (liquefied natural gas) is the only practical way for mass transportation of natural gas across oceans, which accompanies considerable energy consumption in LNG plants. Power generation is one of the effective utilization ways of LNG cold energy which evolves during the vaporization process of LNG with sea water. In this work, performance analysis of two cold energy generation processes, direct expansion and organic Rankine cycles, were carried out by using Aspen HYSYS simulation. The results show that the performance of the organic Rankine cycle is superior to the direct expansion.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.337-344
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• 2017

The demand of liquified natural gas is increasing due to environmental issues. This reason has resulted in increasing the capacity of liquified natural gas cargo tank. The Mark-III type primary barrier directly contacts liquified natural gas. Also, the primary barrier is under various loading conditions such as weight of liquified natural gas and sloshing loads. During a ship operation, various loads can cause fatigue failure. Therefore, the fatigue life prediction should be evaluated to prevent leakage of liquified natural gas. In the present study, the fatigue analysis of insulation system including primary barrier is performed using a finite element model. The fatigue life of primary barrier is carried out using a numerical study. The value of principle stress and the location of maximum principle stress range are calculated, and the fatigue life is evaluated. In addition, the effects on the insulation panel status and the arrangement of knot or corrugation are analyzed by comparing the fatigue life of various models. The insulation system which has best structural performance of primary barrier was selected to ensure structural integrity in fatigue assessment. These results can be used as a design guideline and a fundamental study for the fatigue assessment of primary barrier.

• Journal of Navigation and Port Research
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• v.44 no.4
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• pp.283-290
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• 2020

BOG (Boil Off Gas) generation is unavoidable in the liquefied hydrogen carrier, and proper measures are necessary to prevent pressure problems inside the cargo tank. The BOG can be used as propulsion fuel for ships, and the remaining parts used for propulsion must be effectively managed, such as in the form of reliquefying or burning. This study proposes an BOG reliquefaction system optimized for a 160,000 m3 liquefied hydrogen carrier with a hydrogen propulsion system. The system comprises a hydrogen compression and helium refrigerant section, and increases the efficiency by effectively using the cold energy of the BOG discharged from the cargo tank. In this study, the system was evaluated through the exergy efficiency and SEC (Specific Energy Consumption) analysis according to the rate of the reliquefaction of the BOG while the hydrogen BOG with a supply temperature of -220℃ entered the reliquefaction system. As a result, it showed SEC of 4.11 kWh/kgLH2 and exergy efficiency of 60.1% at the rate of reliquefaction of 20%. And the parametric study of the effects of varying the hydrogen compression pressure, inlet temperature of the hydrogen expander, and the feed hydrogen temperature was conducted.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1116-1117
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• 2015

최근에 개발되고 있는 2세대 고온초전도 선재는 77.3 K의 액화질소보다 높은 임계온도를 가진다. 응용기기의 특성에 따라 액화질소 온도 이하의 다양한 온도 범위에서 운전되고 있다. 이러한 운전 온도의 차이는 초전도 선재의 임계전류 차이를 가져오고, 높아진 임계전류는 시스템의 안정도 측면에서 장점을 가지는 것으로 알려져 있다. 본 논문에서는 다양한 운전 온도 조건에 따른 임계전류에 의한 교류손실 측면의 연구를 진행하였다. 다양한 초전도 권선 형태에서의 임계온도에 따른 교류손실 특성을 수치해석을 통해 확인하고, 시스템의 안정성 향상에 필요한 운전온도에 대한 기본적인 특성 연구를 수행하였다.