• Economic and Environmental Geology
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• v.46 no.2
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• pp.199-206
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• 2013

The Daehyun gold-silver deposit consists of two hydrothermal quartz veins that fill NE-trending fractures in the Cambro-Ordovician calcitic marble. I have sampled wallrock, hydrothermaly-altered rock and gold-silver ore vein to study the element dispersion and element gain/loss during wallrock alteration. The hydrothermal alteration doesn't remarkably recognized at this deposit and consists of mainly calcite, dolomite, quartz and minor epidote. The ore minerals composed of arsenopyrite, pyrrhotite, pyrite, sphalerite, stannite, chalcopyrite, galena, electrum, native bismuth and silver-bearing mineral. Based on analyzed data, the chemical composition of wallrock consists of mainly $SiO_2$, CaO, $CO_2$ with amounts of $Al_2O_3$, $Fe_2O_3(T)$ and MgO. The contents of $SiO_2$, $Fe_2O_3(T)$, MgO, CaO and $CO_2$ vary significantly with distance from ore vein. The element dispersion doesn't remarkably recognized during wallrock alteration and only occurs near the ore vein margin because of physical and chemical properties of wallrock. Remarkable gain elements during wallrock alteration are $Fe_2O_3(T)$, total S, Ag, As, Bi, Cd, Cu, Ni, Pb, Sb, Sn, W and Zn. Remarkable loss elements are $SiO_2$, MnO, MgO, CaO. $CO_2$ and Sr. Therefore, Our result may be used when geochemical exploration carry out at deposits hosted calcitic marble in the Hwanggangri metallogenic district.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.37-53
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• 1993

The polynuclear hydrocarbons (PAHs) emitted from coke oven standpipe were sampled using three sampling systems, including glass fiber filter+silver membrane filter, glass fiber filter+silver membrane filter+XAD-2 adsorbent tube, PTFE membrane filter+XAD-2 adsorbent tube, extracted by methylene chloride and analysed by gas chromathography using flame ionization detector. The results of this study were as follows. 1. Because the amounts of coke oven emissions(COE) were large, the analyses of PAHs were simple and possible without evaporation and concentration. Although the generation of COE was high during early stage of coking, the airborne concentration of PAHs was low and increased during late coking. 2. The contents of PAHs in COE were 1.35-2.81%. 3. The index components of PAHs were fluoranthene and pyrene. Their correlation coefficient to total PAHs were 0.96, 0.95, respectively. 4. The particulate PAHs were sampled by filter and gaseous PAHs by adsorbent tube. The collection efficiency of glass fiber filter+silver membrane filter was 20% of total amount sampled by filters+adsorbent and PTFE membrane filter 50%. Adsorbent tube must be attached to the filter to collect light and small PAH components. 5. The generation of acenaphthene and indeno (1,2,3-cd) pyrene were low and concentrations of fluorene and anthracene were $20-40ug/m^3$ throughout coking time. Other PAH eoncentrations were sometimes high. The generation of PAHs was low at 4-6 hours of coking time. The gaseous PAHs were generated earlier than particulate PAHs.

• Korean Journal of Materials Research
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• v.25 no.2
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• pp.90-94
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• 2015

We prepared 8 samples of non-silver and silver-added master alloys containing silicon to confirm the existence of nickel-silicides. We then prepared products made of 14K and 18K white gold by using the prepared master alloys containing 0.25, 0.35, and 0.50 wt% silicon to check for nickel release. We then employed the EN 1811 testing standard to investigate the nickel release of the white gold products, and we also confirmed the color of the white gold products with an UV-VIS-NIR-color meter. We observed $NiSi_x$ residue in all master alloys containing more than 0.50 wt% Si with EDS-nitric acid etching. For the white gold products, we could not confirm the existence of $NiSi_x$ through XRD after aqua-regia etching. In the EN 1811 test, only the white gold products with 0.25 wt% silicon master alloys successfully passed the nickel release regulations. Moreover, we confirmed that our white gold products showed excellent Lab indices as compared to those of commercial white gold ones, and the silver-added master alloys offered a larger L index. Our results indicate that employing 0.25 wt% silicon master alloys might be suitable for white gold products without nickel-silicide defects and nickel release problems.

• Economic and Environmental Geology
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• v.21 no.3
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• pp.257-268
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• 1988

The Mugeug gold deposits is consisted of more than fourteen gold and silver-bearing quartz veins emplaced in Mesozoic granodiorite mass. In the Samhyungje vein, one of the representative vein in the mine, six stages of mineralizatidns are recognized: Stage I, deposition of base-metal sulfides and gray quartz; stage II, deposition of base-metal sulfides, electrum and white quartz with pinkish tint; stage m, deposition of base-metal sulfides and dark gray quartz; stage N, deposition of native silver, argentite, Ag-tetrahedrite, polybasite, arsenpolybasite and quartz; stage V, deposition of nearly barren quartz; stage VI, deposition of transparent quartz veinlets with minor pyrite. Ag contents of electrum increase steadily from stage II to stage N; 57.25-61.44 atom. % for stage II, 62.85-69.66 atom. % for stage m, 69.79-74.12 atom. % for stage N. Homogenization temperatures of fluid inclusions are as follows; stage II, from $194^{\circ}$ to $287^{\circ}C$; stage V, from $137^{\circ}$ to $171^{\circ}C$, stage VI, from $192^{\circ}$ to $232^{\circ}C$. Salinities of fluid inclusions range from 3.7 to 7.9 wt.% equivalent NaCl in stage II and from 0.8 to 4.3 wt.% equivalent Nael in stage V. Ore mineralogy suggest that temperature and sulfur fugacity declined steadily from $290^{\circ}$ to $150^{\circ}C$ and from $10^{-10.5}$ to $10^{-19.0}$atm. through stage II into stage N. Fluid pressure during stage II inferred from data of mineral assemblages and fluid inclusions is 370bar.

• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.87-91
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• 1993

The morphological hetergeneity of lipopolysaccharides(LPSs) and variation in the O-side chain lengths of LPSs of Salmonella pullorum, which was serially subcultured on the brain heart infusion agar containing $100{\mu}g/m{\ell}$ of acridine orange, was analyzed in Sephadex G-50 column chromatography and silver-stained polyacrylamide gels. The biochemical differences in LPS W and LPS A0150 were identified. Increases in the contents of O-polysaccharides of LPS A0150 than those of LPS W were reflected in the profiles of chromatography and silver-stained polyacrylamide gels. In summary, LPS molecules of S pullorum A0150 appeared to be enriched in the molecules with long O-polysaccharide chains than those of LPS W.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.18-28
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• 2015

This study aims to understand the meaning that learning of the old age has, through old age learners who augustly live after retirement-life so called successful silver years. Qualitative research methods is used for analyzing the contents of articles about 15 old age learners and the results are follows below. First, the retirement has dual meaning for the old learners. One is they experienced psychological and emotional insecurity after retirement and the other is it is a turning point for them to realize their longtime dream. Second, the old age learners showed enthusiasm about learning and they voluntarily found the way of success in their silver years. Finally, the old age learners working in new career with provocative and enthusiastic attitude work as a role model of successful old age life and show how they progress. This study argued that we need to consider the old as active agents and the old age as the time when productive and continuous learning can be done. In addition, this study strongly insisted that we need to realize the importance of 'education by the elderly' and social and other relevant conditions are needed to be established immediately.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.426-429
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• 2017

In this study, we investigated the effect of BN (boron nitride) on the thermal and the electrical conductivity of composites. In case of epoxy/BN composites, the thermal conductivity was increased as the BN contents were increased. Epoxy/AgNP (Ag nanoparticle) nanocomposites exhibited a slight change of thermal conductivity and showed a electrical percolation threshold at 20 vol% of Ag nanoparticles. At the fixed Ag nanoparticle content below the electrical percolation threshold, increasing the amount of BN enhanced the electrical conductivity as well as thermal conductivity for the epoxy/AgNP/BN composites.

• Journal of the Korean Vacuum Society
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• v.12 no.3
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• pp.193-199
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• 2003

Ti-Cu-N and Ti-Ag-N nanocomposite films with various copper and silver contents were synthesized by arc ion plating and magnetron sputtering hybrid system. The structure and mechanical properties of these films were found to be dependant on the copper and silver concentration. The maximum hardness of Ti-Cu-N and Ti-Ag-N films showed approximately 40 ㎬ below 2 at%Me. The role of soft metallic phase in Ti-Me-N nanosturctured films containing one hard and one soft phase is also discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.871-874
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• 2014

Promoting nationwide informatization by means of personal computer and wired Internet since the mid-1990s, the Republic of Korea has systematically dealt with the digital divide of older adults which has been lessened year by year. However, since the introduction of smartphone in Korea in 2009, the smartphone digital divide of older adults has been serious again. Therefore, this research will focus on the present situation and problems of smartphone digital divide of over-65 years old people and will suggest the proper policy solutions such as the enforcement of policy infrastructure, the expansion of smartphone education, the development of UI and contents, and the expansion of silver fare system and silver smartphone.

• Journal of Digital Convergence
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• v.13 no.7
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• pp.323-331
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• 2015

21st Century is getting into Super aging society worldwide basis. Among those population, silver(aged) generation users' physical condition, such as sight, hearing and body, is getting older, especially sight ability which processes 80% of input data, it requires us studying new smartphone GUI designs convergence for the elderly. In light of this social phenomenon, this study suggests smartphone GUI designs convergence guideline for the silver generation through the research of text, icon which are basic elements of smartphone GUI with proper visual attributes. I had inferred UX designs, expert group and evaluation categories from existing papers, related books and designed some displays for the survey. I also offered this guideline with the deep survey of 101 people over 65 years old.