• 대한설비공학회지:설비저널
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• 제8권4호
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• pp.213-220
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• 1979

A number of methods has been developed for calculation of heat transfer in the vertical round tube under conditions of forced convection with uniform heat flux at wall. I would like to express hereby one of applications of this study in the design of heat exchanger instruments for water flow at $15.8^{\circ}C(p_r=8)$ used frequently in our daily life. Also all the results are investigated for forced convective heat transfer in the case of heated water-flow at uniform wall heat flux in the vortical round copper tube, where the ratio of length to diameter will be 44. They are well in agreement with Gratz and Kraussold equation respectively in laminar and transition flow range. In turbulent flow in the range from Re=10,000 to 65,000, the experimental formula Is show as follows ; Nu=0.023 $R_e^{0.814}\;P_r^{0.4}$. And this is agreed with Dittus - Boelter equation when Reynolds number exponent increases from 0.80 to 0.814.

• 설비공학논문집
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• 제14권12호
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• pp.1023-1030
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• 2002

This paper is to research the heat transfer characteristic performance of the copper-water heat pipe with the screen wicks. Recently, the semiconductor capacity of an electronic unit has been larger, on the contrary, its size has been much smaller. As a result, a high-performance cooling system is needed. Experimental variables are inclination angles, temperatures of cooling water and the mesh number of screen wicks. The distilled water was used for the working fluid. At the inclination angle $6^{\circ}$ in top heat mode, the two layers of the 100-mesh screen wick showed the best heat transfer performance. The thermal resistance of the two layers with the 100-mesh screen was 0.7~$0.8^{\circ}C$/W.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.304-307
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• 2003

Replacement of aluminum by copper for interconnections in the semiconductor industry has raised a number of important issues. The integration of copper interconnection can be carried out by CMP(chemical mechanical polishing) is used to planarize the surface topography. In this experiments, we evaluated the optimization of several conditions for chemical additives during Cu CMP process. It was presented that the main cause of grown particle size is tartaric acid. The particle size was in inverse propotion to a quantity of bead and the time of milling process. The slurry stabilizer and oxidizer have been shown to have very good effect by addition in later milling process.

• 한국태양에너지학회 논문집
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• 제28권3호
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• pp.21-26
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• 2008

Solar cells are renewable energy source which is not only environmentally friendly but also economically viable. For that matter, thin film materials are in observed with great in terest by a number of sources throughout the nations. Among these, CdTe (Cadium telluride) and CIS (copper indium diselenide) are the latest commercial products that are gathering attention in the solar cells markets. However there are some downsides to this newly invention. Since the materials are embedded, in the occasion of damage, certain amount of module residue can be released to water or soil. This paper outlines the results of our outdoor leaching experiments on photovoltaic (PV) samples broken into small fragments and been observed for 1 year.

• Structural Engineering and Mechanics
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• 제52권5호
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• pp.957-969
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• 2014

Among severe plastic deformation methods, groove pressing is one of the prominent techniques for producing ultra-fine grained sheet materials. This process consists of imposing repetitive severe plastic deformation on the plate or sheet metals through alternate pressing. In the current study, a 2 mm pure Cu sheet has been subjected to repetitive shear deformation up to two passes. Hardness and tensile yield and ultimate stress were obtained after groove pressing. Fracture toughness tests have been performed and compared for three conditions of sheet material namely as received (initial annealed state), after one and two passes of groove pressing. Results of experiments indicate that a decrease in the values of fracture toughness attains as the number of constrained groove pressing (CGP) passes increase.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.425-426
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• 2008

Elasto-plastic finite element analysis was carried out for analyzing the severe plastic deformation behavior of copper specimens during groove pressing. Deformation localization was studied in terms of strain variations along the longitudinal direction. Plastic strain is lower at the local interface between the shear and the flat regions, which receive very little shear during the pressing cycle. Strain localization is more intensified with the number of rove pressing cycles, although the average strain level increases.

• 미생물학회지
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• 제22권4호
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• pp.243-247
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• 1984

중금속(구리와 카드뮴)이 해양의 표층수와 1m 깊이에서 채취된 미생물군집에 미치는 영향에 관하여 연구되었다. colony 형 성균수와 $^{14}C-glucose$ uptake rate가 배양시간에 따라 각각 측정되었다. 해양에서 채취된 두개의 미생물군집은 서로 상이한 생리적 반응을 나타내었다. 이 결과로서 해양생대체에 토착적인 bacterioneuston population의 존재 가능함을 추정할 수 있다.

• 한국안전학회지
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• 제33권3호
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• pp.15-20
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• 2018

There have been a number of major fatal fire accidents in Korea recently. The number of fires in 2017 were 44,178, which is not only increasing number of fires but also increasing in casualties. Particularly, the fire at Jecheon Sports Center, which suffered many casualties, is expected to have a huge impact. The cause of the fire has not been determined yet, but heat waves on the ceiling have also been pointed out. As such, the copper heating waves, which are used as a preventive measure against damage of pipes due to freezing of pipes, etc., always have a fire hazard. To determine the possibility of a flame-resistant heated fire, a positive electric cable product was used to artificially ignite and analyze the results. In case of a short circuit, the external covering of the positive electric cable is damaged, but not short circuit unless the heating material surrounding the wire is damaged. Due to the characteristics of heating cable for preventing copper waves, the chances of insulation becoming more severe due to moisture and temperature changes are higher than normal wires. If the internal heating system is carbonized by insulating deterioration without damage to the outer coating, it is likely to cause trekking, to form a winding loop in the heating materials, and to cause short circuit in the heated materials. For the positive temperature line, if the middle is shorted, the current continues to flow to the short circuit unless the breaker disconnects. Consequently, a heated fire that does not cut off the power immediately may leave multiple marks or cuts.

• Tribology and Lubricants
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• 제16권5호
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• pp.389-394
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• 2000

Scanning Probe Microscope (SPM) such as Scanning Tunneling Microscope (STM) and Atomic Force Microscope (AEM) was shown to be the powerful tool for nano-scale characterization of material surfaces. Using this technique, surface morphology of the cyclically deformed Cu or Cu-Al single crystal was observed. The surface became proportionately rough as the number of cycles increased, but after some number of cycles no further change was observed. Slip steps with the heights of 100 to 200 nm and the widths of 1000 to 2000 nm were prevailing at the stage. The slipped distance of one slip system at the surface was not uniform, and formation of the extrusions or intrusions was assumed to occur such place. By comparing the morphological change caused by crystallographic orientation, strain amplitude, number of cycles or stacking fault energy, some interesting results which help to clarify the basic mechanism of fatigue damage were obtained. Furthermore, applicability of the scanning tunneling microscopy to fatigue damage is discussed.

• 미생물학회지
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• 제49권4호
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• pp.313-320
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• 2013

정수처리 시설에서 급 배수관으로 많이 사용되는 스테인리스관과 동관에 형성되는 생물막의 특성에 대해 16주 동안 조사하였다. 생물막 반응기는 실제 배급수관의 구조와 유사하게 설계하였으며, 정수처리장으로 유입되는 상수원수와 약품혼화 응집수, 침전수, 여과수, 처리수를 사용하였다. 평균 종속영양세균수는 $1.6{\times}10^4CFU/ml$, $5.8{\times}10^3CFU/ml$, $1.8{\times}10^3CFU/ml$, $1.3{\times}10^2CFU/ml$, 1 CFU/ml로 각 처리 과정을 거치면서 감소하였다. 스테인리스관과 동관에 형성된 생물막 세균수는 원수, 응집수, 침전수에서 2주만에 $2.9{\times}10^3CFU/cm^2$ 이상으로 증가하였고, 동관보다 스테인리스관에서 생물막 세균수가 높게 검출되었다. 여과수(평균 잔류염소 0.44 mg/L)에서는 두 관 재질에 따른 생물막 세균수의 명확한 차이는 없었으며, 5주 이후부터 두 관재질 모두 $18CFU/cm^2$ 이하의 생물막 세균이 검출되었다. 정수(평균 잔류염소 0.88 mg/L)에서는 두 관 재질 모두 생물막 세균이 검출되지 않았다. DGGE 분석결과, 원수, 응집수, 침전수에서 스테인리스관은 Sphingomonadaceae가 우점이였고, 동관에서는 Bradyrhizobiaceae와 함께 Sphingomonadaceae도 우점이였다. 여과수의경우, 5주차 이후 스테인리스관과 동관에 형성된 생물막에서 Propionibacterium sp., Sphingomonas sp., Escherichia sp. 등과 유사한 16S rRNA 유전자 서열을 가지는 밴드들이 검출되었다. 종 풍부도 및 다양성은 동관에 비해 스테인리스관이 더 높게 나타났다.