• 한국가정과학회지
• /
• 제2권1호
• /
• pp.142-148
• /
• 1999

Tencel fabrics were treated with cellulase after mechanical prefibrillation treatment. SEM analysis was carried out to study morphological change of the treated fabric. The cellulase-treated Tencel fabrics were evaluated for weight loss and tensile strength. X-ray diffraction method, moisture regain, and K/S value were used to elucidate crystalline structural changes occurred by cellulase treatment. Degree of polymerization and copper number of the cellulase-treated fabrics were also measured to estimate effect of hydrolysis. SEM analysis indicated that with treatment of prefibrillation and cellulase, fibrils were produced and damage occurred deep into the fiber. Increases in concentration and time of cellulase treatment increased weight loss and decreased tensile strength retention of the treated fabrics. As cellulase hydrolysis progressed, degree of crystallinity, moisture regain and K/S value were not much changed. (Korean J Human Ecology 2(1) : 142∼148, 1999)

• Geomechanics and Engineering
• /
• 제33권3호
• /
• pp.291-299
• /
• 2023

Monitoring contaminants in waste landfills on a seabed is important because the leachate affects the marine ecosystem and facility stability. The objective of this study is to optimize a time-domain reflectometry (TDR) probe using different coating materials and several electrodes to estimate contaminants in saline soil. Copper concentrations ranging from 0 mg/L to 10 mg/L were mixed in 3% salinity water to simulate contaminants in the ocean environment. Epoxy, top-coat, and varnish were used as coating materials, and two to seven electrodes were prepared to vary the number and arrangement of the electrodes. Test results showed that the varnish stably captured the increase in copper concentration, while the other coating materials became insensitive or caused leakage current. In addition, a TDR probe with more electrodes exhibited stable and distinct electromagnetic signals. Thus, the TDR probe with seven electrodes coated with varnish was effectively used to estimate contaminants in saline soil.

• 한국재료학회지
• /
• 제24권11호
• /
• pp.585-590
• /
• 2014

Microstructural evolution in the thickness direction of an oxygen free copper processed by accumulative rollbonding (ARB) is investigated by electron back scatter diffraction (EBSD) measurement. For the ARB, two copper alloy sheets 1 mm thick, 30 mm wide and 300 mm long are first degreased and wire-brushed for sound bonding. The sheets are then stacked and roll-bonded by about 50% reduction rolling without lubrication at an ambient temperature. The bonded sheet is then cut to the two pieces of the same dimensions and the same procedure was repeated on the sheets up to eight cycles. The specimen after 1 cycle showed inhomogeneous microstructure in the thickness direction so that the grains near the surface were finer than those near the center. This inhomogeneity decreased with an increasing number of ARB cycles, and the grain sizes of the specimens after 3 cycles were almost identical. In addition, the aspect ratio of the grains decreased with an increasing number of ARB cycles due to the subdivision of the grains by shear deformation. The fraction of grains with high angle grain boundaries also increased with continuing process of the ARB so that it was higher than that of the low angle grain boundaries in specimens after 3 cycles. A discontinuous dynamic recrystallization occurred partially in specimens after 5 cycles.

• 한국수산과학회지
• /
• 제5권4호
• /
• pp.105-107
• /
• 1972

붕어(Carassius carassius), 가물치(Ophicephalus argus) 및 미꾸리(Misgurnus anguillicaudatus)의 혈색소상에 미치는 동과 염의 영향을 전분전기영동법으로 연구하였다. 1. 정상 붕어의 혈색소 band는 양극에 1개 있고, band의 수나 이동도가 동이나 염에 의하여 영향을 받지 않았다. 2. 정상 가물치의 혈색소 band는 양극 2개 있고, 이동도는 붕어와 미꾸리의 것보다 빨랐으며 동이나 염의 영향을 받지 않았다. 3 정상 미꾸리의 혈색소 band는 2개로서 양극과 음극에 1개씩 있었고, 기준선으로부터의 상대이동도는 서로 비슷하였다 미꾸리가 동에 처리된 경우 양극에 있는 band의 이동도는 대조군과 염처리군의 이동도보다 상당히 빨랐고, 한편 음극에 있는 혈색소 band는 동과 염의 영향을 받지 않았다. 이 연구를 지도하여 주신 숙명여자대학교 약학대학의 노일협박사님께 깊은 감사를 드린다.

• 미생물학회지
• /
• 제43권4호
• /
• pp.337-340
• /
• 2007

Pseudomonas syringae pv. syringae는 우리나라에서 참다래 꽃썩음병의 원인세균으로 알려져 있다. 본 연구에서는 우리나라의 서로 다른 참다래 과수원에서 분리되어 동정된 11개 균주의 꽃썩음병균이 가지고 있는 플라스미드 양상을 pulsed-field 젤 전기영동으로 조사하였다. 그 결과 전체 균주들은 가지고 있는 플라스미드의 개수와 크기에 따라 6개 그룹으로 나누어 졌다. 플라스미드의 수는 0에서 4개, 크기는 22 kb에서 160 kb로 다양하였다. 이들 중 두 개의 플라스미드를 가지고 있는 그를 III에 속하는 4균주가 Cu에 대한 저항성을 보였다. Southern blot hybridization 결과 Cu 저항성 유전자는 48 kb 크기의 플라스미드에 들어 있었다.

• 에너지공학
• /
• 제12권2호
• /
• pp.84-92
• /
• 2003

구리밀봉 증기발생기의 열적크기 계산을 위한 1차원 열수력코드를 개발하였다. 고온 및 저온측 전열관사이의 구리의 열전도는 1차원으로 가정하고, 전열관 피치의 함수로 열저항을 구하였다 물/증기측 유동영역은 아냉, 포화핵비등, 포화막비등, 과열영역의 4 구간으로 구분하였다. 매개변수 연구를 위한 전열관 갯수는 250에서 3500이며, P/D비율은 각각1.4, 1.6, 1.8로 하였다. 계산결과, 전열관 갯수가 2500일 때 전열관 길이는 약 12 m, 직경은 약 3 m이다. P/D를 증가시키면 구리에 의한 열저항 성분이 증가하지만 전열관 길이는 큰 차이가 없음을 알 수 있었다.

• 방사선산업학회지
• /
• 제9권3호
• /
• pp.153-159
• /
• 2015

Reliability of printed circuit board (PCB), which is based on high integrated circuit technology, is having been important because of development of electric and self-driving car. In order to answer these demand, automated X-ray inspection (AXI) is best solution for PCB non-destructive test. PCB is consist of plastic, copper, and, lead, which have low to high Z-number materials. By using dual energy X-ray imaging, these materials can be inspected accurately and efficiently. Dual energy X-ray imaging, that have the advantage of separating materials, however, need some solution such as energy separation method and enhancing efficiency because PCB has materials that has wide range of Z-number. In this work, we found out several things by analysis of X-ray energy spectrum. Separating between lead and combination of plastic and copper is only possible with energy range not dose. On the other hand, separating between plastic and copper is only with dose not energy range. Moreover the copper filter of high energy part of dual X-ray imaging and 50 kVp of low energy part of dual X-ray imaging is best for efficiency.

• Corrosion Science and Technology
• /
• 제16권5호
• /
• pp.247-256
• /
• 2017

The feasibility of using hydrazine for inhibiting pitting corrosion in copper sprinkler tubes was investigated by examining microscopical and structural evolution of corrosion by-products with SEM, EDS, and XRD. Hydrazine removed dissolved oxygen and reduced CuO and $Cu_2O$ as well. The stable phase was changed from CuO to $Cu_2O$ or Cu depending on hydrazine concentration. Hydrazine concentration of 500 ppm could convert all CuO corrosion by-products to $Cu_2O$. In a tightly sealed acryl tube filled with aqueous solution of 500 ppm hydrazine, octahedral $Cu_2O$ particles were formed while plate-like structures with high concentration of Cu, O, N and C were formed near a corrosion pit. The inside structure of a corrosion pit was not altered by hydrazine aqueous solution. Uniform corrosion of copper was almost completely stopped in aqueous solution of 500 ppm hydrazine. Corrosion potential of a copper plate was linearly dependent on log (hydrazine concentration). The concept of stopping pitting corrosion reaction by suppressing oxygen reduction reaction could be verified by applying this method to a reasonable number of real sprinkler systems before full-scale application.

• Tribology and Lubricants
• /
• 제39권6호
• /
• pp.256-261
• /
• 2023

This study is conducted to evaluate the durability of superhydrophobic surfaces, with a focus on two aspects: contact angle measurement and self-cleaning-performance analysis. Superhydrophobic copper and aluminum surfaces are fabricated using the immersion method and subjected to a rolling wear test, in which a 2 kg weight is placed on a rolling tester, under loaded conditions. To evaluate their durability, the contact angles of the specimens are measured for each cycle. In addition, the surface deformation of the specimens before and after the test is analyzed through SEM imaging and EDS mapping. The degradation of the self-cleaning performance is evaluated before and after the wear test. The results show that superhydrophobic aluminum is approximately 4.5 times more durable than superhydrophobic copper; the copper and aluminum specimens could endure 21,000 and 4,300 cycles of wear, respectively. The results of the self-cleaning test demonstrate that superhydrophobic aluminum is superior to superhydrophobic copper. After the wear test, the self-cleaning rates of the copper and aluminum specimens decrease to 72.7% and 83.4%, respectively. The relatively minor decrease in the self-cleaning rate of the aluminum specimen, despite the large number of wear cycles, confirms that the superhydrophobic aluminum specimen is more durable than its copper counterpart. This study is expected to aid in evaluating the durability of superhydrophobic surfaces in the future owing to the advantage of performing wear tests on superhydrophobic surfaces without damaging the surface coating.

• 한국재료학회지
• /
• 제23권12호
• /
• pp.695-701
• /
• 2013

To understand how reactivity between reinforcing nanoparticles and aqueous solution affects electrodeposited Cu thin films, two types of commercialized cerium oxide (ceria, $CeO_2$) nanoparticles were used with copper sulfate electrolyte to form in-situ nanocomposite films. During this process, we observed variation in colors and pH of the electrolyte depending on the manufacturer. Ceria aqueous solution and nickel sulfate ($NiSO_4$) aqueous solutions were also used for comparison. We checked several parameters which could be key factors contributing to the changes, such as the oxidation number of Cu, chemical impurities of ceria nanoparticles, and so on. Oxidation number was checked by salt formation by chemical reaction between $CuSO_4$ solution and sodium hydroxide (NaOH) solution. We observed that the color changed when $H_2SO_4$ was added to the $CuSO_4$ solution. The same effect was obtained when $H_2SO_4$ was mixed with ceria solution; the color of ceria solution changed from white to yellow. However, the color of $NiSO_4$ solution did not show any significant changes. We did observe slight changes in the pH of the solutions in this study. We did not obtain firm evidence to explain the changes observed in this study, but changes in the color of the electrolyte might be caused by interaction of Cu ion and the by-product of ceria. The mechanical properties of the films were examined by nanoindentation, and reaction between ceria and electrolyte presumably affect the mechanical properties of electrodeposited copper films. We also examined their crystal structures and optical properties by X-ray diffraction (XRD) and UV-Vis spectroscopy.