• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.210-210
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• 2010

ABO2 형태를 가진 delafossite 구조 산화물은 p-type 투명전도체 소재로 유명하다. Delafossite 구조가 p-type 투명전도체에 적합한 결정적인 이유는 밴드갭이 넓고 공유결합에 유리하기 때문이다. 투명전도체는 가시광선의 흡수가 없도록 band gap을 넓히는 것이 우선인데 이러한 band gap이 넓은 구조가 delafossite이다. 또한 delafossite 구조는 구조적으로 각각의 산화물 이온들이 유사 사면체 배위(pseudo-tetrahedral coordination)을 갖는다. 이러한 사면체 배위결합구조에서 산소이온은 비결합면이 없기 때문에 더욱더 공유결합성을 향상시킬 것으로 생각된다. 여기서 A는 +1가 cation, B은 +3가 cation으로 구성되어 있다. A자리에는 1가 원소인 팔라듐, 플래티늄, 은, 구리 등을 가질 수 있고. B자리에 3가 원소이면서도 크기가 알루미늄보다는 크고 란타늄보다는 작은 금속이 들어갈 수 있다. Delafossite 구조는 상온에서 2종류의 polytype (상온에서 Rhombohedaral 구조와 hexagonal 구조)이 존재하며 이들은 각각 3R(Rm) 및2H (P63/mmc)의 결정 구조를 가지고 있다. CuCrO2는 일반적으로 3R결정구조를 가지는 것으로 알려져 있다. delafossite 구조는 전기적 이방성을 띄고 있는데 c-축 방향으로의 전기적 특성이 a-축 방향으로의 전기적 특성보다 약 1000배 높은 물성을 띈다고 한다. 이는 c-축 방향의 원자 위치 때문인데 CuCrO2의 경우 Cu-O-Cr-O-Cu로서 3d-2p-3d-2p-3d 궤도를 가지기 때문인 것으로 알려져 있다.[ref] 반면 c-축으로 에피성장된 박막의 경우 +3가 이온이 위치한 layer에서 hole hopping에 의해 캐리어가 전도된다고 알려져 있기도 하다. 본 연구에서는 PLD를 이용하여 c-plane 사파이어 기판위에 성장된 delafossite구조인 CuCrO2박막의 특성을 알아보았다. p-type 특성을 위하여 CuCrO2에 Ni를 첨가하였으며 그에 따른 구조적 전기적 특성을 조사하였다. 성장온도와 도핑농도를 변화시켜 특성을 연구하였다. 결정구조적 특성과 전기적 특성을 분석하려 한다.

• Korean Journal of Metals and Materials
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• v.48 no.12
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• pp.1097-1102
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• 2010

Silver coated copper powders were prepared by a chemical reduction method with controlling the deposition process variables such as the feeding rate of the silver ionic solution and concentration of the reductants at room temperature. The characteristics of the products were evaluated by scanning electron microscope (SEM), X-ray diffractometer (XRD), atomic absorption spectrophotometer (AA) and a 4 probe resistivity measurement system. The optimum condition of the preparation of Ag coated Cu powders was at 0.05 M of potassium sodium tartrate and 2 ml/min of the feeding rate of the silver ionic solution. Our method successfully produced dense, uniform, and well-dispersed Ag coated Cu powder of $2{\sim}2.5{\mu}m$ witha silver layer of 100~200 nm. Additionally, we found that thespecific resistivity of the 30 wt.% Ag coated Cu powder was similar to that of pure silver, so that the composite powder could be used as an alternative electromagnetic shielding material for silver.

• Korean Journal of Heritage: History & Science
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• v.49 no.3
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• pp.4-11
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• 2016

This study compares eight bronze spoons in the Goryeo Dynasty and analyzes their components and lead isotopes in order to confirm the relationship between their production sites and excavation sites. Most of the excavated spoons have elliptical heads, and their handles are categorized into two types. Bronze spoons are made of binary Cu-Sn alloys, but Pb is not added. The same artifacts can have different trace elements depending on location, and the spoons had high Ag content. According to an analysis of their lead isotopic ratio, they were made with raw materials produced in Zone 3 of the South Korean galena map. If the data of the trace elements in the raw ores of the bronze is accumulated, it can be used to indicate the provenance of the artifacts.

• Korean Journal of Materials Research
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• v.29 no.5
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• pp.311-316
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• 2019

Transparent conducting electrodes are essential components in various optoelectrical devices. Although indium tin oxide thin films have been widely used for transparent conducting electrodes, silver nanowire network is a promising alternative to indium tin oxide thin films owing to its lower processing cost and greater suitability for flexible device application. In order to widen the application of silver nanowire network, the electrical conductance has to be improved while maintaining high optical transparency. In this study, we report the enhancement of the electrical conductance of silver nanowire network transparent electrodes by copper electrodeposition on the silver nanowire networks. The electrodeposited copper lowered the sheet resistance of the silver nanowire networks from $21.9{\Omega}{\square}$ to $12.6{\Omega}{\square}$. We perform detailed X-ray diffraction analysis revealing the effect of the amount of electrodeposited copper-shell on the sheet resistance of the core-shell(silver/copper) nanowire network transparent electrodes. From the relationship between the cross-sectional area of the copper-shell and the sheet resistance of the transparent electrodes, we deduce the electrical resistivity of electrodeposited copper to be approximately 4.5 times that of copper bulk.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.954-964
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• 2021

Mirror carp Cyprinus carpio nudus (weight 42.0±3.8 g, length 14.3±0.4 cm) were exposed to different concentrations of waterborne copper (0, 100, 200, 400, 800, and 1,600 ㎍ Cu²⁺·L^-1) at 20.3℃ for 96 h. The lethal concentration 50 of waterborne copper was 1,176.45 ㎍ Cu²⁺·L^-1. Among hematological parameters, red blood cell count was significantly decreased, whereas there were no significant changes in the hemoglobin concentration and hematocrit value. Among the inorganic plasma components, calcium was significantly decreased following copper exposure. Conversely, organic plasma components such as glucose and total protein were significantly increased. Similarly, enzymatic components, such as aspartate transaminase, alanine transaminase, and alkaline phosphatase, were also significantly increased. These findings suggest that the copper exposure is detrimental to the survival rates and physiology of C. carpio nudus.

• Korean Journal of Environmental Agriculture
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• v.4 no.2
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• pp.71-77
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• 1985

Soil samples collected from paddy field adjacent to zinc-mining sites were sequentially extracted to assess chemical fractions of Cd, Zn, Cu and Pb. The purpose of this study was two fold; (i) to examine the chemical forms of heavy metal in soils by sequential extraction. and (ii) to determine relationships between the chemical distribution of heavy metal in the soil and the heavy metal content of the brown rice. The results are summarized as follows. The content of exchangeable, organically bound and carbonate Cd and residual Zn was 73.9% and 63.8% of total Cd and Zn in the soil, respectively. The content of exchangeable Cd, Zn and Pb in soil showed highly negative correlations with pH, organically bound Cd, carbonate Cd, sulfide Cd, Zn and Pb in soil showed highly positive correlations with pH. The content of organically bound Cd, Zn, Pb and carbonate Cu in soil showed highly positive correlations with organic matter content, while the content of sulfide Cu and residual Cd in soil showed highly negative correlation with organic matter content. The content of carbonate Cd, Zn, Pb and residual Cu in soil showed highly positive correlations with CEC, but the content of exchangeable Cd, Zn, Cu, Pb and organically bound Cu in soil showed highly negative correlations with CEC. The content of total, organically bound, carbonate, sulfide and residual Cd in soil were highly correlated with that of Cd in brown rice. The content of any Pb fractions in soil were not correlated with that of Pb in brown rice. The content of water soluble and exchangeable Zn in soil were highly correlated with that of Zn in brown rice.

• Journal of the Economic Geographical Society of Korea
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• v.12 no.2
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• pp.195-214
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• 2009

The Mangi yoram("萬機要覽"), a guidebook of state affairs, was published by royal command in the late Joseon period. Its chapters on financial affairs(財用篇) are particularly remarkable, as they explain on all aspects of the national finance of the late Joseon period in a clear manner. The financial part of the Mangi yoram includes metallic mineral resources, such as the location of gold, silver, copper, lead deposits and the prosperity and decline of the mines, and the various uses of each of the minerals. These are still regarded as valuable resources. Its contents on agricultural geography comprise not only the total yearly output of grains, paddyfields and dryfields, their taxation and standards of taxation, but also ginseng which was famous in the outside world in the pre-modern era. The book also clearly explains distribution of agricultural dikes for irrigation and their functions. The book also contains information on forestry geography, e.g. the varieties of pine trees and their distribution and mountain containment policies. Contents related to commercial geography consist of material on different types of markets such as the yukuijeon(六矣廛), sijeon(市廛), peongsisuh(平市署), nanjeon(亂廛), and the distribution, size and prosperity and decline of the border markets of the northern frontier such as the hoeryungkaesi(會寧開市) and geongwonkaesi(慶源開市). Contents related to transport geography are the distribution and functions of government granaries etc. Obviously, this book contains detailed information on various aspects of Korean geography. If we try to understand the contents of this book from the framework of modern geographical classification schemes, the geographic information contained in the book assumes even greater significance. In sum one may conclude that this book, which the king kept by his side, contained useful geography related knowledge and necessary information, and was directly relevant to the administration of the country. It exerted immense influence on the contemporary intellectual world of Joseon Korea, and was regarded as an invaluable resource.

• Journal of Chest Surgery
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• v.39 no.1 s.258
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• pp.56-59
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• 2006

Background: Spontaneous pneumomediastinum (SPM) is a relatively rare and benign condition that generally occurs in young adults without any precipitating factor or disease. The purpose of this study was to assess whether more uncomforting diagnostic procedures are necessary and to establish standards in the diagnosis and treatment of spontaneous pneumomediastinum. Material and Method: A retrospective study was done on 18 patients from the hospitals of Hanyang University Seoul Hospital and Hanyang University Guri Hospital between February, 1997 and June, 2004. All patients had presence of mediastinal air without a pneumothorax and no evidence of trauma or barotrauma. Result: Among the 18 patients, the majority were male patients with only two female patients. Their mean age was 20.95 years old with standard deviation of 14.3 years. The most common complaints were chest pain, dyspnea, and coughing. Evaluation included simple chest roentgenogram in all patients, 10 patients had a chest tomographic scan, 10 patients had an esophagoscopic exam, 6 patients had a bronchofiberoscopic exam, and 3 patients had an esophagogram done. The mean hospital stay was 10.9 days. All patients were treated conservatively and in a follow-up of 1 $\∼$ 8 years only one recurrence was found. Conclusion: SPM is caused by alveolar rupture in the pulmonary interstitium leading to dissection of air towards the hilum and mediastinum. Although SPM is a self-limiting condition, evaluation should include chest roentgenogram and chest tomographic scans to rule out any other secondary condition. More aggressive evaluation seems unnecessary.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.3
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• pp.207-212
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• 1986

Heavy metal contents and residues level of organochlorine pesticides were analyzed for commercial salted and fermented sea-food which bought from pusan area. Heavy metal contents ranged from 0.11 to 0.46 ppm of mercury, trace to 1.1 ppm of lead, 0.01 to 0.34 ppm of cadmium, 0.4 to 5.98 ppm of cupper, 0.16 to 4.5 ppm of zinc, trace to 0.49 ppm of manganese and trace to 1.35 ppm of arsenic. Residue level of organochlorine pesticides in salted and fermented sea-foods ranged from 0.3 ppb to 1.825 ppb of total BHC Organochlorine pesticides of DDE, dieldrine, pp'-DDD and pp'-DDT were detected a small amount from Ge jeot and Myeol-Chi jeot. In conclusion. the heavy metal and levels of organochlorine pesticides residues were safety to eat the salted and fermented sea foods.

• Culinary science and hospitality research
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• v.19 no.5
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• pp.100-109
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• 2013

This study aims to analyze 19 kinds of mineral contents in hair targeting 311 people in Seoul who suffer from hair loss. The results are as follows: 1. The average contents of all kinds of minerals were within the standards. 2. Sodium, potassium, and selenium were more detected in men than in women; calcium, magnesium, copper, and manganese were more detected in women than in men; toxic elements, mercury, antimony, and arsenic were more detected in men than in women, which was statistically significant. 3. As the age increased, potassium (p<.05), iron (p<.01), manganese (p<.05), chromium (p<.01), and mercury (P<0.01) increased gradually, which was statistically significant. In particular, the content of mercury exceeded its standard in those over fifty. 4. Selenium (p<.01), lead (p<.05), aluminum (p<.05), and arsenic (p<.01) were more detected in natural hair than in permanent or colored hair. Calcium (p<.001), magnesium (p<.001), and manganese (p<.01) were more detected in permanent or colored hair than in natural hair. They were all statistically significant.