• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.476-483
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• 2016

An organic Rankine cycle for ocean thermal energy conversion system is a generating cycle using the temperature difference between surface water and deep water of the ocean. The working fluid is an important factor in the thermodynamic performance of an organic Rankine cycle. There is pinch point analysis as thermodynamic analysis of an organic Rankine cycle. This study performed a thermodynamic performance analysis according to variation in the pinch point temperature difference in heat exchangers and variation of outlet temperature of heat source and heat sink. It analyzed the thermodynamic performance by applying seven types of simple working fluids in a simple Rankine cycle for ocean thermal energy conversion that was designed according to pinch point analysis. As a result of the performance analysis, cycle irreversibility and total exergy destruction factor more decreased, and second law efficiency more increased in the lower pinch point temperature difference and temperature variation of heat source and heat sink in heat exchangers. In addition, the irreversibility changed greatly at a point that occurred in the thermodynamic variation. Among the selected working fluids, RE245fa2 showed the best thermodynamic performance, and the performance of all working fluids was observed to be similar. It needs a strict theoretical basis about diverse factors with thermodynamic performances in selecting heat exchangers and working fluids.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.518-518
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• 2013

자외선이 생체를 파괴하거나 탄생시킬 수 있는 중요한 요소라는 것은 잘 알려져있다. 이 때문에 생체 시료를 보통 자외선 파장대인 250~350 nm보다 짧은 10 nm 영역에 있는 극자외선에 노출되었을 때 그 상호작용 및 변화를 찾아서 분석하는 것을 목표로 삼는다. 먼저 이에 대한 기초내용으로, 앞으로 활용하게 될 플라즈마 집속장치에서의 전극형태에 따른 EUV 광원의 특성을 알아보는 실험을 진행하였다. 이 실험은 집속 플라즈마 발진장치의 2가지 전극인 마테르 (Mather) 형태의 전극과, 초사이클로이달 핀치(Hypercycloidal pinch) 핀치 형태의 전극에서 발진된 극자외선(Extreme Ultraviolet : EUV) 집속 플라즈마의 전자온도와, 전자밀도, power를 분석하였다. 그리고 EUV 광원 발생장치에 Ar 가스와, Ne-Xe 가스내 환경에서 2 종류의 전극에 의해 만들어진 고밀도 플라즈마로부터 발생된 EUV의 특성을 알아보았다.

• The KSFM Journal of Fluid Machinery
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• v.19 no.3
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• pp.19-24
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• 2016

Oil sands are a mixture of sand, clay, and a high-viscosity petroleum called bitumen. Steam-Assisted Gravity Drainage (SAGD) is the most viable and environmentally safe recovery technology for extracting bitumen. It extracts the viscosity-lowered bitumen by high pressure, high temperature steam injected into the bitumen reservoir. The steam is produced at the Central Processing Facility (CPF). Typically, more than 90% of the energy consumed in producing bitumen are used to generate the steam. Fuels are employed in the process, which cause economic and environmental problems. This paper explores the retrofit of heat exchanger network to reduce the usage of hot and cold utilities. The hot and cold utilities are reduced respectively 6% and 37.3% which in turn resulted in 5.3% saving of total annual cost by improving the existing heat exchanger network of the CPF.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.961-976
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• 2006

Designing water-reuse network which can reduce the fresh water within the process and increase the water-use efficiency by scientific and systematic analysis is recently interested in the industries. Water systems often allow efficient water uses via water reuse and recirculation in the paper, petrochemical, and steel industries which necessitate a lot of freshwater within the process. Defining network layout connecting water-using process is frequently accomplished by using water pinch technology which optimizes freshwater entering the process and also reduces the wastewater. In this review, recent researches and case studies of water pinch technology which can find the bottleneck of the water stream at the water reuse designing stage are introduced. Necessity of water pinch technology is illustrated by examples of real industries. Recent studies on simultaneous energy and water minimization and water-reuse network among industries in eco-industrial park(EIP) are also introduced.

• 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.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.63-70
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• 2017

This paper deals with anti-pinch system based on current information which prevents some risks for trapping, squeezing or injury to people in smart window on vehicles. Automatic configuration of current threshold is suggested to recognize pinch states in the current based anti-pinch system. Also, some factors affecting to the squeezing force were analyzed by some experimental results and simulations. The validity of the suggested system was verified to satisfy the strengthened American safety regulation, FMVSS 118-S5, through some experimental results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.3
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• pp.18-24
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• 1977

In this paper, a series inverter circuit is constructed by using the pinch-off characteristics of FET, and itsoutput characteristics is analysed for the variation of gate bias frequency and load. The above constructed circuit could eliminate the unstable output characteristics of SCR-series inverter fir chit by the changes of gate bias frequency and load resistor. But the current capacity of the FET-series inverter circuit is relatively small, and is recommended to be used for light loads.

• Journal of Korea Entertainment Industry Association
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• v.13 no.7
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• pp.145-153
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• 2019

As a category of film types, suspense thriller is constantly introducing a new element in the endless historical development and owns new vitality. The long-standing essence is that it doesn't vulgarly cater to the public, but stimulates more creativity. In this thesis, starting from theoretical foundation of creation in American contemporary suspense thriller, the author analyzes playwriting characteristics of suspense thriller and analyzes the exquisite description of characters' mental world and external presentation in detail from multiple structure modes to multiple perspectives. Also, the author comprehensively elaborates playwriting characteristic features of American contemporary suspense thriller by combining with playwriting theme, structure and viewpoint and takes the classic work of American suspense thriller by David Fincher as an example to analyze the unique value of thriller playwriting.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.11
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• pp.699-707
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• 2017

This study presents a comparative thermodynamic analysis of subcritical and transcritical organic Rankine cycles for the recovery of low-temperature heat sources considering nine substances as the working fluids. The effects of the turbine inlet pressure, source temperature, and working fluid on system performance were all investigated with respect to metrics such as the temperature distribution of the fluids and pinch point in the heat exchanger, mass flow rate, and net power production, as well as the thermal efficiency. Results show that as the turbine inlet pressure increases from the subcritical to the supercritical range, the mismatch between hot and cold streams in the heat exchanger decreases, and the net power production and thermal efficiency increase; however, the turbine size per unit power production decreases.

• Korean Chemical Engineering Research
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• v.45 no.1
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• pp.25-31
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• 2007

In a petrochemical complex, large amount of hydrogen is produced as a by-product and used as a fuel in petrochemical and oil refinery plants. By recycling this byproduct hydrogen as a raw material, the value of hydrogen can be greatly improved. This paper proposes a design methodology for optimal hydrogen recycle network between plants in petrochemical complex by analyzing the hydrogen pinch, required cost and constraints.