• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.339-339
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• 2007

Metal coating on ceramic powder has long been attracting interest for various applications such as superconductor where the brittle nature of high temperature ceramic superconductor was complemented by silver coating and metalloceramics where mechanical property improvement was achieved via electroless plating. More recently it has become of great interest in embedded passive device applications since metal coating on ceramic particles may result in the enhancement of the dielectric properties of ceramic-polymer composite capacitors. In our study, nickel ion-containing solution was used for coating commercial capacitor-grade $BaTiO_3$ powder. After filtering process, the powder was dried and heat-treated in 5% forming gas at $900^{\circ}C$. XRD and TEM were utilized for the observation of crystallization behavior and morphology of the particles. It was found that the nickel coating characteristics were strongly dependent on the several parameters and processing variables, such as starting $BaTiO_3$ particle size, nickel source, solution chemistry, coating temperature and time. In this paper, the effects of these variables on the coating characteristics will be presented in some detail.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.4
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• pp.361-366
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• 2010

Purpose: HCD ion plating apparatus by hollow cathod discharge method was fabricated and TiN films were deposited on stainless steel by this apparatus with increasing in $N_2$ gas flow and the fine color changes of TiN films were analyzed. Methods: The spectroradiometer and spectrophotometer were used to observe optically the fine color changes of TiN thin films, and XPS was used to analyze the compositions of TiN thin films with increasing in $N_2$ gas flow. Results: The color coordinate of TiN thin film with $N_2$ 120 sccm gas flow showed (0.382, 0.372) which had the mixed colors of gold and silver, and the color coordinate changed to the increasing value of (x,y) with increasing in $N_2$ gas flow which indicated the deep gold color. It was found that the slopes of the reflectances at 550nm were increased with increasing in $N_2$ gas flow. And from the Ti scans using XPS, it was found that the peak heights of 455 eV derived from TiN composition were increased with increasing in $N_2$ gas flow, while the peak heights of 459 eV from $TiO_2$ composition were decreased. Conclusions: The results obtained above were that the color of TiN film with 120 sccm $N_2$ gas flow had been observed from the mixed color of silver and gold due to TiC, $N_2$, TiN on the surface and TiN, $N_2$ inside film, and the color of TiN films changed a deep gold color with increasing in $N_2$ gas flow due to increasing TiN composition.

• Korean Journal of Heritage: History & Science
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• v.39
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• pp.243-280
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• 2006

At the Bujang-ri Site, Seosan, South Chungcheong Province, around 220 archaeological features, including semi-subterranean houses and pits of Bronze Age and semi-subterranean houses, pits, and burials of Baekje period had been identified and investigated. In Particular, mound burials No. 5 of 13 of Baekje mound burials yielding a gilt-bronze cap along with other valuable artifacts drew international scholarly attention. The gilt-bronze cap from the mound burial No. 5 is a significant archaeological data not only in the study of Baekje archaeology but also in the study of international affairs and exchange at that time. At the time of exposure, the gilt-bronze cap was already broken into a number of pieces and seriously damaged by corrosion, and hardening and urethane foam were necessary in the process of collecting its pieces. Ahead of main conservational treatments on cap, X-ray photograph and CT(computerizes tomography) were taken in order to examine interior structure of the cap and to decide appropriate treatments. In the five layers identified in the profile of cap, a textile layer was set between a metal and a layerof bark of paper birch for avoiding direct contact of the metal and the bark of paper birch. Analyses were executed for examining textile layer and a layer of fibroid material. According to microscopic analysis, while the textile layer consisted of the simplest plain fabric with one fold among three kinds of textile structures, the layer of fibroid material was mixed with two or three kinds of fibers. A comparative analysis with standard sample using FT-IR (Fourier Transform Infrared Spectroscopy) announced that both textiles and fabrics were hemp. Analysis of kind of the paper birch resulted in barks of paper birch with 15 fold. A metallographic microscope, SEM, and WDS were used for the analysis of microscopic structures of plated metal pieces. While amalgam plating was treated as a plating method, the thickness of the plated layer, a barometer of plating technique, was ranged from $1.72{\mu}m$ to $8.67{\mu}m$. The degree of purity of gold (Au) used in plating was 98% in average, and less than 1% of silver (Ag) was included.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.71-80
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• 2001

Blood and urine mercury level of three workers were monitored during 60~80 days after high exposure to mercury at the silver refining plant. Mercury was used to form silver-mercury amalgam from plating sludge. Workers were exposed to mercury about 70 days at the several processes, such as hand held weaving, vibration table, and heating from the furnace. mercury was analysed by atomic absorption spectroscopy-vapor generation technique. Recovery from the biological sample was 95.51% and pooled standard deviation was 0.033. At the time of study, there was no work at the workplace. So, airborne mercury concentration was measured with area sampling 5 days after the work, ranged from 0.1459 to 1.2351 mg/㎥(Arithmatic mean 0.4711 mg/㎥, Geometric mean 0.3566 mg/㎥) at the inside of the plant, that is far above the ACGIH's TLV(0.025 mg/㎥) and ranged from 0.0073 to 0.0330 mg/㎥ at the outdoor. Blood mercury levels at the beginning of the monitoring were 4~14 times greater than the American Conference of Governmental Industrial Hygienists Biological Exposure Index(ACGIH BEI, 15 ug/L). Blood mercury levels were decreased logarithmically, that is, rapidly at the high level and slowly at the low level but sustained above the level of the ACGIH BEI 60~80 days after the work. Urine mercury levels at the beginning of the monitoring were 8~16 times greater than the ACGIH BEI(35 ug/g creatinine). Urine mercury levels were decreased logarithmically, but correlation between urine level and off-days were lower than those of blood. Decreasing pattern of blood mercury levels were little affected than that of urine levels when the chelating agent, D-penicillamine, was administered. There was correlation between blood mercury level and urine mercury level(0.81~0.83) but it didn\`t mean that the highest blood mercury level corresponded the highest urine mercury level. In our study, Case 1 always shows the highest level in urine but case 3 always shows the highest level in blood. Creatinine correction represented better correlations between urine mercury levels and blood levels, and between urine levels and off-days rather than by urine volume. Spot urine sampling had a wide variation than that of whole day urine sampling. So, We recommend spot urine sampling for screening and whole day urine sampling for exact diagnosis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.11
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• pp.1135-1140
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• 2012

Two-step metallization processes have been proposed to achieve high-efficiency silicon solar cells, where the front-side grids are formed by silver plating after the formation of a nickel seed layer with a mask. Because the conventional mask patterning process is performed by an expensive selective printing method using either UV resist or phase change ink, however, the combination of a simple coating and laser-selective ablation processes is proposed in this study as an alternative means. As a masking material, the solar cell wafer was coated with either inexpensive wax having a low melting temperature or a fluorocarbon solution, and then, an electrode image was patterned by selectively removing the masking material using the laser. It was found that the fluorocarbon coating was not only superior to the wax coating in terms of pattern uniformity but it also increased the efficiency of the solar cell by 0.16%, as confirmed by statistical f and t tests.

• Current Photovoltaic Research
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• v.2 no.4
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• pp.173-176
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• 2014

We have investigated the seed layer formation of front side contact using the inkjet printing process. Conductive silver ink was printed on textured Si wafers with 80 nm thick $SiN_x$ anti reflection coating (ARC) layers and thickened by light induced plating (LIP). The inkjet printable sliver inks were specifically formulated for inkjet printing on these substrates. Also, a novel method to prepare nano-sized glass frits by the sol-gel process with particle sizes around 5 nm is presented. Furthermore, dispersion stability of the formulated ink was measured using a Turbiscan. By implementing these glass frits, it was found that a continuous and uniform seed layer with a line width of $40{\mu}m$ could be formed by a inkjet printing process. We also investigated the contact resistance between the front contact and emitter using the transfer length model (TLM). On an emitter with the sheet resistance of $60{\Omega}/sq$, a specific contact resistance (${\rho}_c$) below $10m{\Omega}{\cdot}cm^2$ could be achieved at a peak firing temperature around $700^{\circ}C$. In addition, the correlation between the contact resistance and interface microstructures were studied using scanning electron microscopy (SEM). We found that the added glass particles act as a very effective fire through agent, and Ag crystallites are formed along the interface glass layer.

• Journal of the Korean Home Economics Association
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• v.44 no.1 s.215
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• pp.131-138
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• 2006

The yanggwan is a striped headpiece for civil and military officials worn with jebok, a costume for the royal ancestral worship ceremony, or jobok, a ceremonial costume for the courtier. It was called a jegwan when it was worn with a jebok. The geumgwan and jegwan are of the same style but the geumgwan has a gilded band and backside and the jegwan is mostly lacquered. The yanggwan was worn first with the jebok by the officials, both of which were received from the Chinese Ming dynasty in the 19th year of the King Gongmin's reign during the Goryeo period. The royal crown and court clothing system was two grades lower than the standard clothing code of the Ming dynasty of China. In the Joseon dynasty, the oyanggwan worn by the highest grade officials had five-stripes but was later replaced during the Daehan Empire by the seven-striped chilyanggwan used by Ming dynasty officials. Oyanggwans make up the majority of the surviving examples of these headpieces, with the exception of the six-striped yukyanggwan of Chung In-hak (1839-1919), the Minister of Justice, which originated in the Daehan Empire and whose owner is definitively known. The gilt portion of this yukyanggwan is finely engraved in relief with a bird, flower and tendril motif. The yukyanggwan is topped by a decorative bird ornament, called a jeongkkot. EDSS spectrum analysis of the gold plating reveals a composition of 51.32% gold and 10.34% silver. The yanggwan is composed of bamboo, mulberry paper and silk crepe. The black portions are lacquered. The individual yang is made with twisted mulberry paper.

• Journal of Preventive Medicine and Public Health
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• v.30 no.3 s.58
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• pp.567-576
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• 1997

To evaluate the effects of reflected glare on eyes, authors assessed the periodic health examination(1991-1996) & self-administered questionnaire data of a semiconductor producing company. The 13 lead frame(LF) department workers have been exposed to high reflected glare in the process for examining the silver plating products. We compared the data of connector(14) and clerical(12) workers as the non-exposed ones. Among LF department workers, 100% felt their visual acuity worsened(connector:81.8%, clerical:85.7%), and 70% had worn the glasses o. contact lenses(connector : 14.3%, clerical :40%) since working at the company. Major ophthalmic symptoms of the LF workers are asthenopia, tearing, decreased visual acuity, congestion and glare. Decrease of visual acuity by Hahn's line change of the LF workers is significantly high during a 5-year follow-up(p<0.05 by simple regression) compared with connector clerical workers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.334-341
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• 2016

In this paper, the study of a waveguide aperture-coupled feed-structured antenna has been conducted for the purpose of applying it to a wireless back-haul system sufficient for high-capacity gigabits-per-second data rates. For this study, a $32{\times}32$ waveguide slot sub-array antenna with a corporate-feed structure was designed and produced. Also, this antenna is used at 57 GHz to 66 GHz in the V-band. The construction of the antenna is a laminated form with radiating parts (outer groove and slot, cavity), a coupled aperture, and feeds in each. The antenna was designed with HFSS, which is based on 3D-FEM, produced with aluminum processed by a precision-controlled milling machine, and assembled after a silver-plating process. The measurement result from analysis of the characteristics of the antenna shows that return loss is less than -12 dB, VSWR < 2.0, and a wide bandwidth ranges up to 16%. An overall first side lobe level is less than -12.3 dB, and a 3 dB beam width is narrow at about $1.85^{\circ}$. Also, antenna gain is 38.5 dBi, offering high efficiency exceeding 90%.

• 보존과학연구
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• s.27
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• pp.129-143
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• 2006

This report is on a scientific investigation of 3 pairs of 금제태환이식 which were excavated from 황남대총 납분. 태환 is a main part of 태환이식 and it could be classified with 4 types in how to produce, especially how many the golden petal was used. In this investigation, they,3 pairs of 금제태환이식 from 황남대총 남분, were in 3 of 4 types and also I could find that this result was not on the technical progress but on the ingredient of metal. Also, In the result of ingredient assay, I could find that although they were in one pair of 태환 one piece was made in gold and silver alloy and the other piece was made in 99.5 percent of pure Ag with gold amalgam plating. And the another pair was getting red from others because of making in 33percent of Ag and 77 percent of gold, high Ag content. And All pairs of 태환 have a small quantity of Copper. As above, although they are one pair they have the difference of how to produce and the difference of volume and ingredient content, it means that these pairs of 태환 from 황남대총 남분 were made in pressure of time. From now on, if we investigate the ingredient and how to produce of 태환이식 in the local comparative analysis, namely natural science method, we can find out the metal art technique and the social aspect of the ancient times as not analogical inference but scientific basis.