• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.819-824
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• 1989

This paper proposes a new method for the discovery and design of an optimal heat exchanger network. The method is based upon the concept of pinch, a problem reduction technique and the heuristics developed in this work. It generates subproblems in a logical way and solves the subproblems by the heuristics to synthesize an optimal network structure. It is thought that the heuristics can preserve the minimum utility consumption, the minimum number of heat exchanger units, and the minimum number of stream splittings needed for a given problem. The minimum heat exchanger area for the optimal network can then be obtained by adjusting the temperatures associate with the heat exchanger in the optimal network structure. The method is applied to the problems appeared in the literatures. The results show the reductions in the number of heat exchanger units for some problems.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.94-97
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• 2005

For the fabrication of poly-crystalline silicon ingot, CCCC (Cold Crucible Continuous Casting) method under a high frequency alternating magnetic field, was utilized in order to prevent crucible consumption and ingot contamination and to increase production rate. In order to effectively and continuously melt and cast silicon, which has a high radiation heat loss due to the high melting temperature and a low induction heating efficiency due to a low electric conductivity, Joule and pinch effects were optimized. Throughout the present investigation, poly-crystalline Si ingot was successfully produced at the casting speed of above 1.5 mm/min under a non-contact condition.

• Progress in Superconductivity and Cryogenics
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• v.8 no.4
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• pp.34-38
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• 2006

Cycle analysis was performed in order to find the optimum design point of the LNG Boil-off gas re-liquefaction system. Thermodynamic analysis revealed the system could be defined by three state variables. Thus the system performance could be described by the three cold endpoint temperatures of the three-pass heat exchanger. This enabled us to investigate the cycle performance in terms of the heat exchanger parameters. To get access to the cycle states of higher system performances, larger heat exchangers were found necessary. Also the thermal pinch in cryogenic heat exchangers was found to act as a limiting factor to the system performance.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.670-678
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• 1999

Heat recovery steam generator(HRSG) is a principal component of the combined cycle power plant (CCPP) which utilizes the waste energy of the gas turbine exhaust gas. A design of the HRSG is a keypoint to achieve high cycle efficiency with competitive cost. This paper presents a brief review on the design of a HRSG which covers the basic design parameters and their effects on the performance and the investment cost. Finally the concept of the optimum design point is presented according to the selection of a pinch point temperature difference and a steam pressure as an illustrated case.

• Restorative Dentistry and Endodontics
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• v.27 no.6
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• pp.587-599
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• 2002

Extracellular single unit recordings were made from the ventral posteromedial thalamic (VPM) nociceptive neurons to determine mechanoreceptive field (RF) and response properties. A total of 44 VPM thalamic nociceptive neurons were isolated from rats anesthetized with urethane-chloralose. Based on responses to various mechanical stimuli including touch, pressure and pinch applied to the RF, 32 of 44 neurons were classified as nociceptive specific (NS) neuron. The other 12 neurons, classified as wide dynamic range (WDR), showed a graded response to increasingly intense stimuli, with a maximum discharge to noxious pinch. The VPM nociceptive neurons showed various spontaneous activity ranged from 0-6 Hz. They were located throughout the VPM, and had an contralateral RF including mainly intraoral (and perioral) regions. The RF size was relatively small, and very few neurons had a receptive field involving 3 trigeminal divisions. The NS neurons activated only by pressure and pinch stimuli had high mechanical thresholds compared to WDR neurons activated also by touch stimuli. The VPM nociceptive neurons were tested with suprathershold graded mechanical stimuli. Most of 21 NS and 8 WDR neurons showed a progressive increase in number of spikes as mechanical stimulus intensity was increased. In some neurons, the responses reached a peak before the highest intensity was given. Application of 5 mM $CoCl_2{\;}(10{\;}{\mu}\ell)$ solution to the trigeminal subnucleus caudalis did not produce any significant changes in the spontaneous activity, RF size, mechanical threshold, and response to suprathreshold mechanical stimuli of 9 VPM nociceptive neurons tested. 17 of 33 VPM nociceptive neurons responded to noxious heat as well as noxious mechanical stimuli applied to their RF. Application of the mustard oil, a small-fiber excitant and inflammatory irritant, to the right maxillary first molar tooth pulp induced an immediate but short-lasting neuronal discharges upto approximately 4 min in 16 of 42 VPM nociceptive neurons. These results suggest that VPM thalamic nucleus may contribute to the sensory discriminative aspect of orofacial nociception.

• 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.

• 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 Journal of Materials Research
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• v.13 no.12
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• pp.769-774
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• 2003

In this paper, we report on the DC characteristics of the AlGaN/GaN HFETs using physical models on piezoelectric and thermal effects. Employing the models was found to be essential for a realistic prediction of the DC current-voltage characteristics of the AlGaN/GaN HFETs. Though use of the implementation of the physical models, peak drain current, transconductance, pinch-off voltage, and most importantly, the negative slope in the current were accurately predicted. The importance of the heat sink effect was demonstrated by the comparison of the DC characteristics of AlGaN/GaN HFETs fabricated from different substrates including sapphire, Si and SiC. Highest peak current was achieved from the device with SiC by an effective suppression of heat sink effect.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.56-63
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• 1995

MESFETs of the Ti/Au and Ti/Pd/Au gate were fabricated on n-type GaAs. Interdiffusion at Schottky interfaces, Schottky contact properties, and MESFET characteristics with heat treatment were investigated. Ti of Ti/Au contact and Pd of Ti/Pd/Au contact acted as a barrier metal against interdiffusion of Au at >$220^{\circ}C$. Pd of Ti/Pd/Au contact acted as a barrier metal even at >$360^{\circ}C$, however, Ti of Ti/Au contact promoted interdiffusion of Au instead of role of barrier metal. As the heat treatment temperature increases, in the case of both contact, saturated drain current and pinch off voltage decreased, open channel resistance increased, and degree of parameter variation in Ti/Au gate was higher than in Ti/Pd/Au gate at >$360^{\circ}C$ Schottky barrier height of Ti/Au and Ti/Pd/Au contacts was 0.69eV and 0.68eV in the as-deposited state, respectively, and Fermi level was pinned in the vicinity of 1/2Eg. As the heat treatment temperature increases, barrier height of Ti/Pd/Au contact increased, however, decreased at >$360^{\circ}C$ in the case of Ti/Au contact. Ideality factor of Ti/Au contact was nearly constant regardless of heat treatment, however, increased at >$360^{\circ}C$ in the case of Ti/Au contact. From the results above, Ti/Pd/Au was stable gate metal than Ti/Au.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.549-559
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• 2005

Sustainable industrial development which can minimize an ecological effect by the mankind exertion is recently interested due to an environmental contamination and a resource exhaustion problem. An eco-industrial park (EIP) is a community of manufacturing and service businesses seeking enhanced environmental and economic performance through collaboration in managing environmental and resource issues, including energy, water, and materials. EIP developments which improve a production plant within an eco-friendly greenfield and design a new industrial ecosystem are accomplished recently, which can efficiently re-use the waste and resources from each company within EIP. In this review, the outside and domestic case studies of EIP and cornerstone technologies to develop the EIP, such as energy integration, waste reuse, mass flow analysis, water pinch, and life cycle assessment, are summarized.