• 동력기계공학회지
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• 제13권6호
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• pp.76-81
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• 2009

Thermal desorption systems are designed to remove organic compounds from solid matrices such as soils, sludges and filter cakes without thermally destroying them. It is a separation technology, not a destruction technology. Since it is a thermal process, there is a common belief that temperature is the only significant parameter to be monitored. While it is true that better removal efficiencies are usually achieved at higher temperatures, other factors must be considered. Since the process is governed by mass transfer, heating time and the amount of mixing are also key parameters in optimizing removal efficiency. Thermal desorption have been successfully used for just about every organic contaminant found to date. It has also been used to remove mercury. In the present study, the numerical simulation has been performed to investigate the characteristics of heat transfer of LTTD(low temperature thermal desorption). The commercial software, AMESIM was applied for analyzing the heat transfer process in the LTTD.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권1호
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• pp.17-25
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• 2005

This paper provides sufficient conditions for the robustness of Affine linear TFM(Transfer Function Matrix) MIMO (Multi-Input Multi-Output) uncertain systems based on Rosenbrock's DNA (Direct Nyquist Array). The parametric uncertainty is modeled through a Affine TFM MIMO description, and the unstructured uncertainty through a bounded perturbation of Affine polynomials. Gershgorin's theorem and concepts of diagonal dominance and GB(Gershgorin Bands) are extended to include model uncertainty. For this type of parametric robust performance we show robustness of the Affine TFM systems using Nyquist diagram and GB, DNA(Direct Nyquist Array). Multiloop PI/PB controllers can be tuned by using a modified version of the Ziegler-Nickels (ZN) relations. Simulation examples show the performance and efficiency of the proposed multiloop design method.

• 대한전기학회논문지:전력기술부문A
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• 제52권7호
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• pp.363-370
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• 2003

This paper presents the analysis of the load transfer capacity and study of conductor size for variable contingencies in distribution systems. The operation capacity of feeders was changed to improve operation efficiency in KEPCO, considerations for contingencies are still based on the previous capacity. In order to cope with the changes such as operation capacity, it is necessary to study whether the present "contingency support criteria" is reasonable or not, also to confirm the whether the present criteria should be improved or not. We analyze the load transfer capacity and conductor size on a distribution system for contingency levels such as the substation-level, bank-level, feeder-level, and zone-level.one-level.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.11-16
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• 2001

Recent publications showed that a pair of neighboring printed circuit board (PCB) windings can be used as a contactless energy transfer device. As a continued study on this area, the current paper presents the modeling, analysis, and application of the neighboring PCB windings with an emphasis on their circuit properties and device characteristics as a contactless energy transfer device. Theoretical results of the paper are confirmed with experiments on a prototype contactless energy transfer circuit that delivers 24W output power at $68\%$ efficiency through two 35mm-diameter PCB windings separated each other by 2.4mm.

• Journal of Advanced Marine Engineering and Technology
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• 제25권3호
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• pp.581-587
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• 2001

Plate heat exchange(PHE) will be applied to the refrigeration and air conditioning systems as evaporators or condensers for their high efficiency and compactness. The purpose of this study is the analyze the characteristics of heat transfer and pressure drop of plate heat exchanger. Numerical work was conducted using the FLUENT code k-$\varepsilon$model. Also the dependence of heat transfer coefficient and friction factor on Reynolds number was investigated. As the Reynolds number increases, it is found that heat transfer coefficient also increases, but friction factor decreases. The study examines the internal flow, thermal distribution and the pressure distribution in the channel of plate heat exchanger. The results of CFD analysis compared with experimental data, and the difference of friction factor and Nusselt number in plate heat exchanger are 10% and 20%, respectively, Therefore the CFD analysis model is effective for the performance prediction of plate heat exchanger.

• Journal of Mechanical Science and Technology
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• 제15권5호
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• pp.639-645
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• 2001

Experimental investigations were conducted to study forced convection of fully developed turbulent flows in horizontal equilateral triangular ducts with different surface roughness pitch ratios (P/e) of 4, 8, and 16 on one side. The ducts bottom wall was heated uniformly and the other surfaces were thermally insulated. To understand heat transfer enhancement mechanism, heat transfer rates were measured. Smooth triangular ducts were also tested for benchmark purposes. The results were compared with previous results for similarly configured channels, at which they were roughened by regularly spaced transverse ribs in the rectangular and circular channels.

• 한국수정란이식학회지
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• 제30권4호
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• pp.305-313
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• 2015

Xenotransplantation of pig islet regarded as a good alternative to allotransplantation. However, cellular death mediated by hypoxia-reoxygenation injury after transplantation disturb success of this technique. In the present study, we produce transgenic pig expressing human heme oxygenase 1 (HO1) genes to overcome cellular death for improving efficiency of islet xenotransplantation. Particularly, Korean miniature pig breed, Micro-Pig, was used in the present study. Somatic cell nuclear transfer (SCNT) technique was used to produce the HO1 transgenic pig. Six alive transgenic piglets were produced and all the transgenic pigs were founded to have transgene in their genomic DNA and the gene was expressed in all tested organs. Also, in vitro cultured fibroblasts derived from the HO1 transgenic pig showed low reactive oxygen species level, improved cell viability and reduced apoptosis level.

• 한국정밀공학회지
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• 제19권11호
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• pp.146-159
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• 2002

An efficient method to predict the convection heat transfer coefficients on the top surface of the engine piston is proposed. The method is based on the inverse method of the thermal conduction problem and uses a numerical optimization technique. In the method, the heat transfer coefficients are numerically obtained so that the difference between analyzed temperatures from the finite element method and measured temperatures is minimized. The method can be effectively used to analyze the temperature distribution of engine pistons in case when application of prescribed-temperature boundary condition is not reasonable because of insufficient number of measured temperatures. A hollow sphere problem with an analytic solution is taken as a simple example and accuracy and efficiency is demonstrated. The method is applied to a practical large liquid petroleum gas(LPG) engine piston and the heat transfer coefficients on the top surface of the piston is successfully calculated. Resulting analyzed temperature favorably coincides with measured temperature.

• Membrane and Water Treatment
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• 제4권3호
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• pp.191-202
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• 2013

The application of ultrafiltration operation to the dialysis in countercurrently parallel-flow rectangular membrane modules was investigated. The assumption of uniform ultrafiltration flux was made for operation with slight concentration polarization and declination of transmembrane pressure. Considerable improvement in mass transfer is achievable if the operation of ultrafiltration is applied, especially for the system with low mass transfer coefficient. The enhancement in separation efficiency is significantly increased with increasing ultrafiltration flux, as well as with increasing the volumetric flow rates. Furthermore, increasing the volumetric flow rate in retentate phase is more beneficial to mass transfer than increasing in dialysate phase.

• 설비공학논문집
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• 제11권4호
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• pp.431-439
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• 1999

A generator-GAX combined rectification system of an ammonia absorption heat pump was investigated to get the optimum design values. The mass and heat transfer phenomena of the rectification system were analysed. The number of column plates, equilibrium temperature of solution on each plate and flow rates of solution and vapor generated were predicted. The characteristics of mass and heat transfer of the generator-GAX combined rectification system, i.e. concentration difference of leaving solution and vapor on each column plate, were found to be mainly governed by the pressure of generator, reflex ratio and temperature difference of analyser coolant. The number of rectification column plates for each different pressure in generator was obtained. The optimum locations for installing the feeder from solution-cooled absorber and GAX desorber in generator were predicted. The improvement of COP was followed by the increase of the rectifier efficiency and the number of column plate, and the decrease of reflex ratio.