• 한국분말재료학회지
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• 제21권3호
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• pp.202-206
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• 2014

Leaching of MOCVD dust in the LED industry is an essential stage for hydro-metallurgical recovery of pure Ga and In. To recover Ga and In, the leaching behavior of MOCVD scrap of an LED, which contains significant amounts of Ga, In, Al and Fe in various phases, has been investigated. The leaching process must be performed effectively to maximize recovery of Ga and In metals using the most efficient lixiviant. Crystalline structure and metallic composition of the raw MOCVD dust were analyzed prior to digestion. Subsequently, various mineral acids were tested to comprehensively study and optimize the leaching parameters such as acidity, pulp density, temperature and time. The most effective leaching of Ga and In was observed for a boiling 4 M HCl solution vigorously stirred at 400 rpm. Phase transformation of GaN into gallium oxide by heat treatment also improved the leaching efficiency of Ga. Subsequently high purity Ga and In can be recovered by series of hydro processes.

• 한국대기환경학회지
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• 제22권6호
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• pp.808-820
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• 2006

In regard to indoor air quality patterns, the government introduced various polices that were about managing and monitoring quality of indoor air as a major assignment, and also executed 'Indoor Air Quality Management Act' which was presented in the May, 2004. However, among the multi-usage facilities controlled by the Act, the school was not included yet. This study goal was to investigate PM 10 pollution patterns of the high school classrooms using a pattern recognition method based on cluster analysis and disjoint principal component analysis, and further to survey levels of inorganic elements in May, June, and September, 2004. A hierarchical clustering method was examined to obtain possible objects in pseudo homogeneous sample classes by transformation raw data and by applying various distance. Following the analysis, the disjoint principal component analysis was used to define homogeneous sample class after deleting outliers. Then three homogeneous Patterns were obtained as follows: the first class had been separated and objects in the class were considered to be sampled under semi-open condition. This class had high concentration of Ca, Fe, Mg, K, Al, and Na which are related with a soil and a chalk compounds. The second class was obtained in which objects were sampled while working air-conditioners and was identified low concentration of PM 10 and elements. Objects in the last class were assigned during rainy day. A chalk, soil element and various types of anthropogenic sources including combustions and industrial influenced the third class. This methodology was thought to be helpful enough to classify indoor air quality patterns and indoor environmental categories when controlling an indoor air quality.

• 자원환경지질
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• 제26권4호
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• pp.455-464
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• 1993

Some nodules occur in the Milyang pyrophyllite deposit which are hydrothermal alteration products by Late Cretaceous andesitic tuff. These nodules are divided into two types on the basis of mineral assemblages; diaspore and pyrophyllite nodules. The diaspore nodules consist mainly of diaspore, kaolinite, pyrophyllite and pyrite with a small amounts of wavellite and tourmaline. They are light purplish grey in color, ellipsoid in shape and range 1 cm to 15 cm in size. A small or large diffuse band exists in some nodules. The platy coarse-grained diaspore is intergrown with the fine-aggregated kaolinite in the central part of the nodule. It appears that the grain size become fine from center to margin. The pyrophyllite nodules, which have the same shape with diaspore nodules, consist dominantly of pyrophyllite accompanied by small amounts of quartz, kaolinite, svanbergite, wavellite, tourmaline and apatite. Chemical compositions of alteration zones and nodules show that the wall rock alteration involved mainly the removal of large quantities of silica and alkalies and small quantities of Ca, Mg and Fe. The sharp increase in the Al content of the nodules is the result of residual concentration of alumina by the leaching of the mobile components. The pyrophyllite nodules were formed in the fluid saturated with quartz as ${\mu}_{HK_{-1}}$ and ${\mu}_{H_{2}O}$ increase. Under this condition, the pyrophyllite-kaolinite-quartz assemblage was stable. Diaspores formed from pyrophyllites in the fluid undersaturated with quartz as ${\mu}_{H_{2}O}$ increases (decreasing temperature). Under this condition, diaspore-pyrophyllite-kaolinite assemblage become stable. The formation temperature of the nodules on the basis of mineral assemblage is estimated as $275{\sim}340^{\circ}C$.

• 한국대기환경학회지
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• 제16권1호
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• pp.11-22
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• 2000

Polycyclic aromatic hydrocarbons(PAHs) have known as potentially hazardous air pollutants(HAPs0 to human health because of its carcinogenic and mutagenic behaviors. The purpose of this study was to determine the level of 6 PAHs(Fluoranthene, Pyrene, Benzo[a]anthracene, Chrysene, Benzo[b]fluoranthene, and Benzo[a]pyrene) as well as 10 inorganic elements(Cr, Na, K, Zn, Pb, Fe, Cu, Ti, Al and Cd) in the ambient PM-10. The total of 115 samples had been collected from February, 1996 to June, 1996 on quartz fiber by a PM-10 high volume air sampler near the Yong-Tong Apartment complexes. A statistical analysis was performed for the PAHs and inorganic elements data set using a principal component analysis in order to identify qualitatively the potential sources of PM-10. A total of 6 principal components were separated by intensive data pretrement and transformation processes, such as soil, refuse incineration, oil burning, coal burning, field burning, vehicle emission sources. The results showed that PAHs were associated with various burning activities like refuse and field burning, coal burning, and oil burning emissions in the study area. These derived sources were well matched with the previously known source profiles in terms of compositonal order and level of measured species. The combination data set consisted of both organic and inorganic species might provide more powerful source signature and might increase the number of potentially derived sources than PAHs or inorganic data alone.

• International Journal of Advanced Culture Technology
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• 제3권1호
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• pp.153-160
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• 2015

This article is aimed to study the effects of resistance spot welding (RSW) on the lap joint properties between AA1100 aluminum alloy and SGACD zinc coated steel and its properties. The summarized experimental results are as follows. The summarized experimental results are as follows. The optimum welding parameters that produced maximum tensile shear strength of 2200 N was a welding current of 95 kA, a holding time of 10 cycles, and a welding pressure of 0.10 MPa. Increasing of welding current, increased the tensile shear strength of the joint and also increased the amount of aluminum dispersion at the joint interface. The lap joint of steel over the aluminum (Type I) showed the higher joint tensile shear strength than a lap joint of aluminum over the steel (Type II). The indentation depth and the ratio of the indentation depth to the plate thickness decreased when the welding current was increased in the type I lap joint and also decreased when the welding current was decreased in the type II lap joint. The interface structure showed the formation of the brittle $FeAl_3$ intermetallic compound that deteriorated the joint strength.

• Journal of Magnetics
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• 제9권4호
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• pp.116-120
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• 2004

Hexagonal barium-ferrite ($BaFe_{12}O_{19}$, magnetoplumbite structure; BaM) film with perpendicularly c-axis orientation was successfully deposited on (100) silicon substrates with an MgO (111) underlayer by rf diode sputtering and in-situ heating at $920^{\circ}C$. The magnetic and structural properties of 0.27 ${\mu}m$ thick BaM films on MgO (111) underlayers were compared to films of the same thickness deposited onto single-crystal MgO (111) and c-plane ($000{\ell}$) sapphire ($Al_2O_3$) substrates by vibrating sample magnetometry (VSM), x-ray diffractometer (XRD), and atomic force microscopy (AFM). The thickness dependence of MgO (111) underlayers on silicon wafer was found to have a large effect on both magnetic and structural properties of the BaM film. The thickness of 15 nm MgO (111) underlayers produced BaM films with almost identical magnetic and structural properties as the single-crystal substrates; this can be explained by the lower surface roughness for thinner underlayer thicknesses. The magnetization saturation ($M_s$) and the ratio $H_{cII}/H_{c{\bot}}$ for the BaM film with a 15 nm MgO (111) underlayer is 217 emu/cc and 0.24, respectively. This is similar to the results for the BaM films deposited on the single-crystal MgO (111) and sapphire substrates of 197 emu/cc and 0.10, 200 emu/cc and 0.12, respectively. Therefore, the proposed MgO (111) underlayer can be used in many applications to promote c-axis orientation without the cost of expensive substrates.

• Nuclear Engineering and Technology
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• 제40권6호
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• pp.497-504
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• 2008

In a study of the optimum operational condition for a melting decontamination, the effects of the basicity, slag type and slag composition on the distribution of depleted uranium were investigated for radioactively contaminated metallic wastes of iron-based metals such as stainless steel (SUS 304L) in a direct current graphite arc furnace. Most of the depleted uranium was easily moved into the slag from the radioactive metal waste. The partitioning ratio of the depleted uranium was influenced by the amount of added slag former and the slag basicity. The composition of the slag former used to capture contaminants such as depleted uranium during the melt decontamination process generally consists of silica ($SiO_2$), calcium oxide (CaO) and aluminum oxide ($Al_2O_3$). Furthermore, calcium fluoride ($CaF_2$), magnesium oxide (MgO), and ferric oxide ($Fe_2O_3$) were added to increase the slag fluidity and oxidative potential. The partitioning ratio of the depleted uranium was increased as the amount of slag former was increased. Up to 97% of the depleted uranium was captured between the ingot phase and the slag phase. The partitioning ratio of the uranium was considerably dependent on the basicity and composition of the slag. The optimum condition for the removal of the depleted uranium was a basicity level of about 1.5. The partitioning ratio of uranium was high, exceeding $5.5{\times}10^3$. The slag formers containing calcium fluoride ($CaF_2$) and a high amount of silica proved to be more effective for a melt decontamination of stainless steel wastes contaminated with depleted uranium.

• 동굴
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• 제21권22호
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• pp.17-56
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• 1990

Cheju Island, which was formed by volcanic activity, is an oval in its shape with the major axis of 80km and the minor axis of 40km. The island holds in its heart Mt. Hanla rising 1,950m above the sea. Petrological study of this volcanic island has been made actively by Sang-Man Lee, Chong-Kwan won and Moon-Won Lee. The chronological measurements of the island by Chong-Kwan Won and Moon-Won Lee showed that it is composed of Sanbangsan trachytes and Backlokdam trachytes(25,000 year ago). These reports are based on the chemical analysis and the rediometric chronological measurements on the ground. However, there has been no reports about the inside of caves. We made an (composition) analysis of the inside of Manjang Cave by the fundamental parameter method in X-ray fluorescence spectrometry. The fundamental parameter method in X-ray fluorescence spectrometry is nondestructive analysis, and it enables us to make the values processed by a computer. The results obtained by this methods are as follows : SiO$_2$(49％), $Al_2$O$_3$(17％), Fe$_2$O$_3$(13％), CaO(8.1％), MgO(5.5％), Na$_2$O(3.6％), TiO$_2$(2.1％), $K_2$O(0.86％), P$_2$O$_{5}$(0.28％), and MnO(0.20％), respectively. The data obtained by the fundamental parameter method in X-ray fluorescence was compared with the data provided by Chong-Kwan and Moon-Won Lee. Our measurement was made by K-Ar-method in cooperation with T.ITAYA. The samples are of 30,000～420,000 year ago. The composition of the values of our underground analysis with the existing values obtained by the analyses on the ground produced new data about Cheju volcanic island.d.

• 복식문화연구
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• 제18권2호
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• pp.371-381
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• 2010

The pine needles can be used for four seasons in normal living and it can be taken friendly everywhere as it is distributed over 50% in Korea. The pine needles consist of vitamins, protein, minerals, essential oil and enzyme related to antimicrobial activity. It has effect like high blood pressure, neuralgia and hanged over by terpene, glucokinin, rutin, apigenic acid and tannin. Also the extract of them can be used for dyeing of fabrics. However, the extract components and effects of them are not well known yet. Therefore, the purpose of this study was to investigate the volatile components of the pine needles extract and functionality. The pine needles extract was dyed into various fabrics(nylon, silk, wool and soybean) and mordanted with Al, Cu, Cr, Fe and Sn. The extracted aroma compounds were compared by gas chromatography-mass spectrometry. The major volatile compounds of pine needles verified by using SPME were alpha-pinene, beta-pinene, beta-phellandrene, caryophyllene, ethanon, benzen. A total of 15 compounds were identified by using the SPME fibers. In the UV-visible spectra, the maximum absorption of wavelength of the pine needles ethanol extract appeared at 460, 630nm for chlorophyll component and at 237, 281nm for tannin component with the pine needles distilled water extract. Most of sample showed high antibacterial effect in none mordant but wool fabric showed high antibacterial effect in mordants. The result of UV block test showed a superior ability of blocking ultraviolet ray infiltration in all sample.

• 복식문화연구
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• 제17권4호
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• pp.575-582
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• 2009

The coffee has been used as drink in the world and it has been using not only food but also dyeing. It can be used for four seasons in our normal living and it can be taken friendly everywhere. The coffee consists of about 8${\sim}$10% phenol(chlorogenic acid) that related to antioxidant and antimicrobial activity. However, its exact components and the dyeing property effects has not been well known yet. Therefore, the purpose of this study was to investigate the dyeing property and ultraviolet-cut ability of silk and nylon fabrics that was dyed variously with coffee extracts. Coffee extracts were done by boiling coffee with distilled water at $100^{\circ}C$ for 2 hours. As mordanting agent, we used $AlK(SO_4)_2$ $12H_2O$, $CuSO_4$ $5H_2O$, $FeCl_2$ $4H_2O$. As the result of the dyeing properties and ultraviolet-cut ability of fabrics dyed with coffee bean extracts, we can find that the optimum dyeing temperature and dyeing time of the silk and nylon fabrics dyed with coffee bean extracts was $90^{\circ}C$, 60 min. and the colorfastness of washing and dry-cleaning was improved by using mordanting agent(4${\sim}$5 grade). Ultraviolet-cut ability was showed more 90% in dyed nylon fabrics.