• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.881-889
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• 2015

Ocean thermal energy conversion is an organic Rankine cycle that generates power using the temperature difference between surface water and deep water. This study analyzes the thermodynamic efficiency of the cycle, which strongly depends on the working fluid and the cycle configuration. Cycles studied included the classical simple Rankine cycle, Rankine cycles with an open feedwater heater and an integrated regenerator, as well as the Kalina cycle. Nine kinds of simple refrigerants and three kinds of mixed refrigerants were investigated as the working fluids in this study. Pinch-point analysis that set a constant pinch-point temperature difference was applied in the performance analysis of the cycle. Results showed that thermodynamic efficiency was best when RE245fa2 was used as the working fluid with the simple Rankine cycle, the Rankine cycles with an open feedwater heater and an integrated regenerator, and when the mixing ratio of $NH_3/H_2O$ was 0.9:0.1 in the Kalina cycle. If the Rankine cycles with an open feedwater heater, an integrated regenerator, and the Kalina cycle were used for ocean thermal energy conversion, efficiency increases could be expected to be approximately 2.0%, 1.0%, and 10.0%, respectively, compared to the simple Rankine cycle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.123-127
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• 2005

LRE(liquid rocket engine) performance design code with several modules for each engine component has been developed for a preliminary design purpose. Thrust chamber, non-cryogenic centrifugal pump, single stage axial impulse turbine, gas generator and exhaust pipe for extra thrust have been considered. For simplicity, pump exit pressures are fixed, which eliminates pressure balancing problem between thrust chamber and turbopump unit. In this paper, calculated performance parameters with system flow charts and the design methodologies for each component are briefly presented and the results are compared with tile real engine specification.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.1-8
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• 2016

It was examined that start-up characteristics of a staged combustion cycle engine powerpack. Among various parameters, valve opening time was considered as a main factor affecting the start-up characteristics. Using monte-carlo method, characteristics variation was analyzed when the valve opening time deviates from the nominal value. As a result, the main fuel valve opening time and the start turbine ending time were significant associated with the startup characteristics. When separating main fuel valve opening time and start turbine stop time, main fuel valve opening time was an important factor. For stable operation, the main fuel valve opening time must be set one second before after driving the start turbine. Likewise, it was confirmed that the startup analysis can suggest an appropriate startup sequence for a stable startup.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.67-74
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• 2019

In this paper, mathematical models of a simulation code are presented. The simulation code was developed for the startup analysis of an open cycle liquid rocket engine (LRE). Most of the components comprising an LRE, including the priming process in the propellant feeding line, were considered. A startup simulation of a 75-tonf LRE, which was used for the KSLV-II test launch vehicle (TLV), was performed. The simulation results showed good agreement with the engine acceptance test results, thus proving the validity of the startup simulation code.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.761-764
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• 2005

컨텍스크 기반 미들웨어는 응용 도메인에서 실제 상황을 구현할 수 있다. 전형적으로 실제 위치를 환경에 메핑시킴으로서 실제상황을 가변적으로 변화시킬 수 있다. 또한 실제 위치에 센서와 actuator 를 이용한 서비스의 라이프사이클을 원격지에서도 가변적으로 변경할 수 있다. 이 시스템은 CAMUS[1] 시스템에서 라이프 사이클 관리를 OSGi 기반으로 한 내용을 구현하였다. OSGi 는 홈 네트워크 관련 개방형 시스템 게이트웨이 시스템으로서 OSGi 를 이용함으로써 다양한 유비쿼터스 통신, 가정, 컴퓨터 시스템간의 쉽게 라이프 사이클 관리를 할 수 있는 장점이 있다.

• TTA Journal
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• s.167
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• pp.124-127
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• 2016

Smart Connectivity를 위한 IoT, 네트워킹, 보안 솔루션을 제공하는 (주)브로드웨이브는 자사만의 경쟁력을 통해 벤처기업 인증, 이노비즈기업 인증, 기업부설연구소 설립 등 내실있는 기업으로 발돋움하고 있다. 특히, 개방과 공유로써 성공적인 IoT 비즈니스를 만들기 위해 국제 표준 기반의 개방형 IoT 서비스 개발에 주력하고 있다. 이의 일환으로, 사용하지 않는 중고 스마트폰을 활용하여 IoT 표준화를 통해 다른 스마트폰이나 PC, 노트북 간의 게이트웨이로서 기능케 하는 기술을 개발 중이다. 이를 위해서는 많은 전문가로부터 다양한 관점을 전달받는 것이 중요했고, 고민 끝에 TIA의 중소 중견기업을 위한 표준 자문서비스의 도움을 청하게 되었다.

• Journal of the Korean Solar Energy Society
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• v.26 no.2
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• pp.9-18
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• 2006

In this paper, the thermodynamic performance of OTEC cycle was examined. Computer simulation programs were developed for simple Rankine cycle, regenerative Rankine cycle, Kalina cycle, open cycle and hybrid cycle. For the simple Rankine cycle, the results show that newly developed fluids such as R410A and R32 that do not cause stratospheric ozone layer depletion perform as well as R22 and ammonia. Also, simple Rankine cycle OTEC power plant can practically generate electricity when the difference in warm and cold sea water inlet temperatures are greater than $14^{\circ}C$. The regenerative Rankine cycle showed a 1.5 to 2% increase in energy efficiency compared to the simple Rankine cycle while the Kalina cycle employing ammonia/water mixture showed a 2-to-3% increase in energy efficiency, and the overall cycle efficiencies of hybrid cycle and open cycle were 3.35% and 4.86%, respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.21-33
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• 2020

In this study, the program for system analysis of an expander cycle rocket engine using liquid hydrogen as a fuel was developed. The properties of hydrogen were considered by the ratio of isomers with temperature. The analysis procedure was established with the open and closed types of the expander cycle engine and the simulation methods were suggested for each component. To validation of the analysis program, we compared the performance of the engine operating point and the analysis results performed overseas for Vinci and SE-21D, which are expander cycle engines. As a result of the analysis, the main performance factors of the system, such as the mass flow of the propellant, specific thrust, and power, except for some of the inaccurate input information, showed high accuracy with an error of around 1-2%.

• Informatization Policy
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• v.26 no.3
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• pp.90-106
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• 2019

The cloud services market is growing rapidly from the on-premises environment to the cloud computing environment and the domestic cloud software market in Korea is expected to grow at a CAGR of around 15%. In Korea, research teams are providing open cloud platforms using open source software under the government taking the initiative, which intends to enhance the reliability and functionality of open cloud platforms, provide users with a world-class open cloud platform-based and developer-friendly environment that is managed on heterogeneous cloud infrastructure and supported by full-lifecycle management of application software. In this paper, we propose a method to utilize CaaS in the open cloud platform, through incorporating the platform with the container orchestration platform. Finally, by providing users with the application runtime and container runtime, it presents how the two platforms can coexist and cooperate in the same ecosystem.

• Journal of the Korean Solar Energy Society
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• v.30 no.3
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• pp.124-130
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• 2010

Ocean Thermal Energy Conversion(OTEC) power plants have been examined as a viable option for supplying clean energy. This paper evaluated the thermodynamic performance of the OTEC Power system for the production of electric power and desalinated water. The results show that newly developed fluids such as R32, R125, R143a, and R410A that do not cause stratospheric ozone layer depletion perform as well as R22 and ammonia. Overall cycle efficiency of open cycle is the lowest value of 3.01% because about 10% of the gross power is used for pumping out non-condensable gas. Also, the hybrid cycle is an attempt to combine the best features and avoid the worst features of the open and closed cycles. The overall cycle efficiency of hybrid cycle is 3.44% and the amount of desalinated water is 0.0619 kg/s.