• Journal of Environmental Science International
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• v.23 no.11
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• pp.1807-1820
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• 2014

The spatial and temporal changes of the annual mean urban heat island(UHI) intensity were investigated using near surface temperature data measured at 16 automatic weather systems(AWS) in Busan metropolitan area(BMA) during the 11-yr period, from 2000 to 2010. For nighttime, the annual mean UHI intensity at Dongnae(U1) in 2000 was weaker than it in 2010. However the change of the annual mean UHI intensity at Daeyeon(U2) during 11 years was different from it at U1. The annual frequency of the UHI intensity over $5^{\circ}C$ considerably increased at U2 and decreased at U1 during 11 years. The center of the UHI also spatially shifted southward with Daeyeon and Haeundae in BMA. It would be caused by the increase of urban area, population-density and transportation near U2 and by the decrease of them near U1. We found that the spatial and temporal differences of the UHI intensity have coincided with changes of land-use, population density and transportation in BMA.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.4
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• pp.173-177
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• 2013

Separation and recovery of valuable metals such as zinc, nickel or tin from copper alloy dross has recently attracted from the viewpoints of environmental protection and resource recycling. In this report, preliminary study on concentration and separation of tin from copper alloy dross using selective dissolution method was performed. The tin in the copper alloy dross did not dissolve in the nitric acid solution which could allow the concentration and separation of the tin from the copper alloy dross. Precipitation of tin as $H_2SnO_3$ (metastannic acid) occurred in the solution and transformed to tin dioxide ($SnO_2$) after drying process. The dried sample was heat-treated at low temperature and its phase characteristics, surface morphology and chemical composition were investigated.

• Journal of Energy Engineering
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• v.10 no.4
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• pp.327-334
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• 2001

Heat is wasted by unconcern in industrial complex. This paper presented for using waste heat, which investigated step by step from searching waste heat to starting construction before and directly applied for the using waste heat in the actual site. Especially, using heat is assessed by investigation of heat supply and demand. Design of heat transportation system was made base on analysis of heat balance between demand and supply, which was analyzed by economical efficiency and property. Payback-period on investment was 1,909 years that was comparatively a short period of time in assessment.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.114-120
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• 2014

The purpose of this study is to conduct the study of the combustion and thermal characteristics through transportation oil for the analysis of fire hazard. Transportation oil breaks down into fuels such as diesel for civilian demands, gasoline, DF1(diesel for military), high sulfur diesel(for marine), kerosene and JP1(for aviation), and lubricants like brake fluid, power steering oil, engine oil, and automatic and manual transmission oil. The experiments of flash point, ignition point, flame duration time, heat release rate were carried out using TAG closed cup flash point tester(AFP761), Cleveland open cup auto flash point analyzer(AFP762), KRS-RG-9000 and Dual cone calorimeter. As a result, the fuel's ignition points were lower than lubricants, especially that of gasoline was not conducted as it has below zero one. Gasoline has the highest ignition point of about $600^{\circ}C$, while the other fuels showed $400{\sim}465^{\circ}C$. For flame duration time, lubricants had over 300 seconds, but fuels had less than 300 seconds except high sulfur diesel(350 seconds). Total heat release rate ranged $287{\sim}462kW/m^2$ for lubricants and gasoline showed the highest total heat release rate, $652kW/m^2$.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.376-379
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• 1996

Synthesis for qualitative analysis in connection with quantitative analysis from the pinch design method, EVOP and Operations Research is proposed for the optimal synthesis of heat exchanger networks, that is through of the transportation model of the linear programming for synthesizing chemical processing systems, to determine the location of pinch points, the stream matches and the corresponding heat flowrate exchanged at each match. In the second place, according to the optimization, the optimal design of heat transfer enhancement is carried on a fixed optimum heat exchanger network structure, in which this design determines optimal operational parameters and the chosen type of heat exchangers as well. Finally, the method of this paper is applied to the study of the optimal synthetic design of heat exchanger network of constant-decompress distillation plants.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.6
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• pp.250-255
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• 2018

The CoCrMo as-built alloys prepared by 3D-printing process are studied on tensile strength, wear resistance, crystal structure and microstructure after complex heat-treatment including HIP. In this study, HIP treatment for removing micropores, ambient heat-treatment for formation of metal carbides, and solution heat-treatment for homogenization of the created metal carbides were tried and characterized for applying to artificial joint. The complex heat-treatment effects of the CoCrMo as-built alloys prepared by 3D-printing process were owing to the densification during HIP, formation of metal carbides and homogenization of the created metal carbides. The effects of the complex heat-treatment were confirmed by XRD, FE-SEM and EDS.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.633-637
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• 2023

Recently, with the development of the smart device market, the integration of high-functional devices has increased the heat density, causing overload of the device, and resulting in various problems such as shortened lifespan, performance degradation, and failure. Therefore, research on heat dissipation materials is being actively conducted to realize next-generation electronic products. The heat dissipation material is characterized in that it is easy to dissipate heat due to its high thermal conductivity and minimizes leakage current flowing through the heat dissipation material due to its low electrical conductivity. In this study, flower-shaped Al₂O₃ and BN composites were engineered with a simple hydrothermal synthesis approach, and their thermal conductivity characteristics were compared and evaluated for each synthesis condition for the application to a heat dissipation material. Spherical BN and flower-shaped Al₂O₃ were easily obtained, and SEM/EDS analyses confirmed the uniform presence of BN between the Al₂O₃, and it can be expected that these shapes can affect the thermal conductivity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.1-11
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• 2016

The effect of the migration of nanoparticles near the wall of a channel on the convective heat transfer in a laminar flow of $SiO_2$ nanoparticle suspensions (nanofluids) under constant wall heat flux boundary conditions was numerically and experimentally investigated in this study. The dynamic thermal conductivity of the aqueous $SiO_2$ nanofluids was measured using T-type thermocouples attached to the outer surface of a stainless steel circular tube (with a length of 1 m and diameter of 1.75 mm). The nanofluids used in this study were synthesized by dispersing $SiO_2$ spherical nanoparticles with a diameter of 24 nm in de-ionized water (DIW). The enhancement of the thermal conductivity of the nanofluids (e.g., an increase of up to 7.9 %) was demonstrated by comparing the temperature profiles in the flow of the nanofluids with that in the flow of the basefluids (i.e., DIW). However, this trend was not demonstrated in the computational analysis, because the numerical models were based on continuum assumptions and flow features involving nanoparticles in a stable colloidal solution. Thus, to explore the non-continuum effects, such as the modification of the morphology caused by nanoparticle-wall interactions on the heat exchanging surfaces (e.g., the isolated and dispersed precipitation of the nanoparticles), additional experiments were performed using DIW right after the measurements using the nanofluids.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.1
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• pp.48-54
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• 2014

A refrigeration dehumidifier with a recuperative heat exchanger is theoretically analyzed. The recuperative heat exchanger is located between the two air streams from and to the dehumidifying coil, and reduces the sensible heat load in dehumidification process. A simple model is developed to predict performance of the dehumidifier. The model predicts that the recuperative heat exchanger is effective especially in the low humidity condition, where the sensible heat load is relatively large. It is predicted that, by adopting a recuperative heat exchanger, a maximum 30~110% increase in COP is possible for indoor air at $27^{\circ}C$, and 40~60% relative humidity.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.515-518
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• 2007

Gas hydrates are ice-like crystalline compounds that form under low temperature and elevated pressure conditions. Recently, gas hydrates present a novel means for natural gas storage and transportation with potential applications in a wide variety of areas. An important property of hydrates that makes them attractive for use in gas storage and transportation is their very high gas-to-sol id ratio. In addition to the high gas content, gas hydrates are remarkably stable. The main barrier to development of gas hydrate technology is the lack of an effective mass production method of gas hydrate in solid form. In this study, some performance comparison among several cases classified by different volume sizes of solution were carried to identify the characteristics due to the volume increment. And it is found that one of the main reasons disturbing hydrate formation is related to the lack of cooling heat transfer due to the volume increase of the solution. So, three kinds of heat transfer plates which have different shapes and cross sectional areas were made and tested for the performance comparison following to the shape and area of each plate. Finally it is clarified that the heat transfer is one of the major factors effecting hydrate formation performance and the installation of heat transfer plate can enhance the formation performance especially not in terms of the quantity but the speed.