• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.922-923
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• 2006

Thermal management is one of the critical aspects in the design of highly integrated microelectronic devices. The reliability of electronic components is limited not only to operating temperature but also by the thermal stresses caused during the operation. The need for higher power densities calls for use of advanced heat spreader materials. A copper diamond composite has been developed with high thermal conductivity $(\lambda)$ and tailorable coefficient of thermal expansion (CTE). Copper diamond composites are processed via gas pressure assisted infiltration with different copper alloys. Emphasis has been placed on the addition of trace elements in deisgning the copper alloys to facilitate a compromise between thermal conductivity and mechanical adhesion. The interfaces between the alloy and the diamond are related to the thermal properties of these copper composites.

• 설비공학논문집
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• 제12권3호
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• pp.251-257
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• 2000

District heating and cooling systems offer highly efficient energy utilization and maintenance by centralizing heat management. More pumping power, however, is required because the water has to travel long distance from heat source to the users. In the present study, a trace of drag reduction additives is added to the District Cooling system to achieve a significant drag reduction and save pumping power. Water-soluble polymers, surfactants, and environment-friendly degradable polymers are used as effective drag reducing additives. Time dependent percent drag reductions are compared for various additive solutions at 100 wppm concentration for different water velocity. Without as an anionic surfactant, copolymer was most effective in percent drag reduction. It is found that there exists an optimal condition when copolymer is mixed with SDS. An environment-friendly degradable polymer, xanthan gum, is found to be a significant drag reduction additive. Ice slurry systems, can give less pressure drops compared with chilled water system for certain condtions. Drag reduction additives were also effective for the ice slurry system.

• 대한치과보철학회지
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• 제25권1호
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• pp.95-118
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• 1987

This study was undertaken to observe the elemental transition of Interface depending on different pretreatment methods, the number of filings, the kinds of porcelain powders and the various alloys in ceramo-metal restoration. The materials used in this study were Pors-on $4^{(R)}$ and Ceramco porcelain powder to compare the differences depending on the pretreatement methods and the number of firings. Ceramco porcelain powder and Vita porcelain powder were used to compare the differences of elemental transition depending on the porcelain powders. The $Parasil^{(R)},\;PGV^{(R)}$ and Pors-on $4^{(R)}$ as Pd-Ag alloy were used to compare the difference of elemental transition depending on the various alloys. The pretreatment methods were : no treatment, treatment under vacuum and air, treatment with 50 % hydrofluoric acid and double heat tretament. The number of firings were 3, 5 and 7 repeated firings All specimens were observed by SEM and concentration of elements were analyzed quantitatively with EPMA The results of this study were obtained as follows : 1. In the groups of air-treatment, concentration of Sn were the highest and widest. A high concentration of In were in the groups of vacuum and air treatment. 2. There were no significant differences in concentration of Sn between the group of vacuum, 5 minutes hydrofluoric acid and double heat treatment. (p>0.05) 3. As the period of time of hydrofluoric acid treatment increased, not only were the trace elements reduced but the main components such as Pd and Ag were also reduced. 4. Concentration of Sn and In increased and diffused with repeated firings but 5 repeated and 7 repeated firings groups had no significant differences. (p>0.05) 5. Sn were more concentrated in the group of Ceramco porcelaion powder than Vita porcelain powder. 6. The higher concentration of trace elements in the alloy, the more increasing concentration of Sn and In in the interface.

• 한국진공학회지
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• 제6권4호
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• pp.293-297
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• 1997

점성진공계(spinning rotor gauge, SRG)는 고진공영역인 1${\times}$10-5∼100Pa에서 전달표 준기(transfer standard gauge)로 사용되고 있는 진공게이지이다. 제조회사가 각각 Leybold-Heraeus와 MKS회사인 두 개의 SRG에 대해서 질소가스를 사용하여 장기안정성과 적응계수(accommodation coefficient, $sigma$)결정에 영향을 미치는 변수들인 측정압력, 온도, 최 대도달압력(base pressure), 신호분산(signal scattering), 영점(offset)변화에 대한 특성을 10 개월에 걸쳐 조사하였다. 이 결과 장기안정특성 및 입력변수들에 의한 영향이 SRG 고유오 차인 $pm$1.0% 이내에 있음을 확인하였다.

• 한국화재조사학회지
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• 제4권1호
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• pp.62-69
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• 2004

본 연구는 소규모 작업장내 화재사건 중 발생 빈도가 높은 부분에 속하는 유형인 안전장치 없는 시즈히터(sheath heater)의 사용중 발생하는 화재사례에 대한 현장 조사에서 필요한 감정 감식 상의 특이점을 알아보기 위해 사례를 바탕으로한 발화 가능 조건을 A, B, C, D로 분류하여 실험을 수행 검토한 바, 안전장치가 없는 시즈히터는 사용중 축열조건으로 방치할 경우 급격히 온도가 상승하여 주변가연물에 착화되었으며, 그러한 경우 전원선에서 단락흔의 발견이 없는 경우라도 히터 발열부에 변색흔 등이 관찰되는 특징점을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4759-4775
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• 2022

The RVACS is a versatile and robust safety system driven by two natural circulations: in-vessel coolant and ex-vessel air. To observe interaction between the two natural circulations, SINCRO-IT facility was designed with two different similarity laws simultaneously. Bo' based similarity law was employed for the in-vessel, while Ishii's similarity law for the ex-vessel excluding the radiation. Compared to the prototype, the sodium and air system, SINCRO-IT was designed with Wood's metal and air, having 1:4 of the length reduction, and 1.68:1 of the time scale ratio. For the steady state, RV temperature limit was violated at 0.8% of the decay heat, while the sodium boiling was predicted at 1.3%. It showed good accordance with the system code, TRACE. For an arbitrary re-criticality scenario with RVACS solitary operation, sodium boiling was predicted at 25,100 s after power increase from 1.0 to 2.0%, while the system code showed 30,300. Maximum temperature discrepancy between the experiments and system code was 4.2%. The design and methodology were validated by the system code TRACE in terms of the convection, and simultaneously, the system code was validated against the simulating experiments SINCRO-IT. The validated RVACS model could be imported to further accident analysis.

• 한국축산식품학회지
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• 제43권6호
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• pp.989-1001
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• 2023

Processed foods containing pork fat tissue to improve flavor and gain economic benefit may cause severe issues for Muslims, Jews, and vegetarians. This study aimed to develop an indirect enzyme-linked immunosorbent assay (iELISA) based on a monoclonal antibody specific to thermal stable-soluble protein in pork fat tissue and apply it to detect pork fat tissue in heat-processed (autoclave, steam, roast, and fry) beef meatballs. To develop a sensitive iELISA, the optimal sample pre-cooking time, coating conditions, primary and secondary dilution time, and various buffer systems were tested. The change in the iELISA sensitivity with different 96-well microtiter microplates was confirmed. The detection limit of iELISA performed with an appropriate microplate was 0.015% (w/w) pork fat in raw and heat-treated beef. No cross-reactions to other meats or fats were shown. These results mean that the iELISA can be used as an analytical method to detect trace amounts of pork fat mixed in beef.

• 대한치과교정학회지
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• 제22권3호
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• pp.557-578
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• 1992

Heat treatment which removes internal stress enhances the mechanical properties of the orthodontic arch wire. The main purpose of this experiment was to investigate the effects of the heat treatment on the mechanical properties of the Elgiloy wire. The Elfiloy wire, 0.016' X 0.022' and 0.018' X 0.025', were heat treated in an electric oven for 5, 10 and 15 minutes at selected temperatures between 300 and $900^{\circ}C$. Tensile strength and load deflection rate were measured to reveal the changes of mechanical property at various conditions, and each specimen was observed under metallurgic microscope. Also to trace the precipitation material due to overheat treatment, a qualitative analysis was carried out with EDS system. It was found that heat treatment at a low temperature caused an increase in the tensile strength and bending resistance, and a maintenance in the fibrous in the tensile strength and bending resistance, and a maintenance in the fibrous structure of both sizes of wire. The changes observed in properties and appearance were probably due to the relief of internal stresses incurred in the metal during cold working. In both sizes of wire the tensile strength and the bending resistance continued to decrease at high temperature, and the fibrous structure continued to disappear then was not observed at $900^{\circ}C$. The carbide precipitation founded in grain boundary at $750^{\circ}C$ probably was other elements carbide (Ni, Co) except Cr. The grain growth was observed at $1100^{\circ}C$. Optimum heat treatment for the 0.016' X 0.022' Elgiloy wire was 10 minutes at $500^{\circ}C$, and for the 0.018' X 0.025' Elgiloy wire it was 5 to 15 minutes at $500^{\circ}C$.

• Preventive Nutrition and Food Science
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• 제18권4호
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• pp.256-262
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• 2013

Four functional constituents, oxyresveratrol 3'-O-${\beta}$-D-glucoside (ORTG), oxyresveratrol (ORT), t-resveratrol (RT), and moracin (MC) were isolated from the ethanolic extract of mulberry (Morus alba L.) twigs by a series of isolation procedures, including solvent fractionation, and silica-gel, ODS-A, and Sephadex LH-20 column chromatographies. Their chemical structures were identified by NMR and FABMS spectral analysis. Quantitative changes of four phytochemicals in mulberry twigs were determined by HPLC according to cultivar, producing area, and heat processing. ORTG was a major abundant compound in the mulberry twigs, and its levels ranged from 23.7 to 105.5 mg% in six different mulberry cultivars. Three other compounds were present in trace amounts (<1 mg/100 g) or were not detected. Among mulberry cultivars examined, "Yongcheon" showed the highest level of ORTG, whereas "Somok" had the least ORTG content. Levels of four phytochemicals in the mulberry twigs harvested in early September were higher than those harvested in early July. Levels of ORTG and ORT in the "Cheongil" mulberry twigs produced in the Uljin area were higher than those produced in other areas. Generally, levels of ORTG and ORT in mulberry twigs decreased with heat processing, such as steaming, and microwaving except roasting, whereas those of RT and MC did not considerably vary according to heat processing. These results suggest that the roasted mulberry twigs may be useful as potential sources of functional ingredients and foods.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2402-2407
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• 2007

Heat transfer distributions and friction factors in square channels (3.5 ${\times}$ 3.5 cm) with twisted tape inserts and with twisted tape inserts plus interrupted ribs are respectively investigated. Tests are performed for Reynolds numbers ranging from 8,900 to 29,000. The rib height-to-channel hydraulic diameter, e/Dh, is kept at 0.057 and test section length-to-hydraulic diameter, L/Dh is 30. The twisted tape is 0.1 mm thick carbon steel sheet with diameter of 3.3cm, length of 90cm, and 2.5 turns. The square ribs are arranged to follow the trace of the twisted tape and along the flow direction defined as axial interrupted ribs. Each wall of the square channel is composed of isolated aluminum sections. The following conclusions from the experimental study were drawn as: 1) In the 4 heating wall channel with twisted tape inserts, Nusselt number based on bottom wall temperature is enhanced by 1.2 - 1.6 times if adding the axial interrupted ribs on the bottom wall only. 2) The twisted tape with interrupted ribs under the two-sided heating condition produces the highest heat transfer performance. 3) Friction factor data obtained for the square channel with twisted tape inserts plus axial interrupted ribs are less than those in the past publications for circular tubes with axial interrupted ribs and twisted tape inserts.