• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.178-183
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• 2002

Zinc fluosilicate ($ZnSiF_6$, 15% aqueous solution) was prepared using zinc oxide (ZnO) and fluosilicic acid ($H_2SiF_6$) by soluiton synthetic method. The fluidity and hydration properties of cement which was added $ZnSiF_6$ (aq.) as an additive for cement were studied. At water to cement ratio (W/C) equals to 0.45, the initial fluidity and slump loss of cement paste which the addition of $ZnSiF_6$ (aq.) was increased from 1.0% to 4.0% based on cement weight were investigated. Initial fluidity of cement paste was measured by mini-slump test and slump loss was examined by measuring the fluidity variation of cement paste with time elapsed from 0 min to 120 min at intervals 30 min. Also, the effect of $ZnSiF_6$ addition on the setting and hydration of cement paste when $ZnSiF_6$ increased in the addition range 1.0% to 3.0% were investigated. The fluidity of cement paste which was added 2.1% $ZnSiF_6$ (aq.) presented the highest value among all addition ranges. The setting time of cement paste was retarded gradually and the heat evolution of hydrated cement was reduced with the increasing of $ZnSiF_6$ addition.

• Fashion & Textile Research Journal
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• v.9 no.2
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• pp.176-187
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• 2007

Buddhist paintings in the late Joseon dynasty are characterized by diversification and subdivision of subject matters. Buddhist paintings rapidly declined since 19th century, being miniaturized and showing complicated composition. Figures that identified the shape of shoes in Buddhist paintings of late Joseon dynasty included sacheonwang that were placed in the left and right bottom of Buddhist paintings, sinjung, gwiwang and pan-gwan of siwangtaeng. Sacheonwang, an Indian folk god, was depicted as a noble person in "ahamgyeong", an early sutra, but was depicted as an armored warrior in Mahayana Buddhism world. The style of shoes sacheonwang in Korea were different depending on the times. The shoes of the sacheonwang sculpture in Seogguram of Shilla dynasty are sandal type. The sacheonwang that was drawn on Jijangbosaldo in Goryeo dynasty wears non-showy armor and red yi(履). The sacheonwang that was expressed on Buddhist paintings in Joseon dynasty wears showy armor and decorated hwa. Comparing the yi of Goryeo Jijangbosaldo sacheonwang with the yi of Bodhisattva on the Dunhuang yeolbanbyeonsangdo, Jijangbosaldo sacheonwang's shoes are Korean style in which the sole is flat and the front part has no decoration, but in the shoes of Bodhisattva on the Dunhuang yeolbanbyeonsangdo the sole is not flat, the front part is lifted. The style of shoes of pan-gwan, who is depicted on Siwangtaeng, is hwa. However, unlike the decorative hwa of sacheonwang, its front is not lifted and it has no decoration. It is assumed that the shoes of sacheonwang or pan-gwan represented obangsaek based on the idea of eumyang-ohaeng. Depiction of shoes shown in Buddhist paintings reflected the phases of the social life. In addition, the sandals of Shilla sacheonwang implies that sourthern culture in addition to Buddhism was introduced. Having expressed the shoes of Goryeo sacheonwang with conventional yi implies that Buddhism governed the inner world of the people, and the shape and material of the shoes reveals aristocracy. It is assumed that that an armored warrior wore yi, not hwa implies that the then society was stable. Also, it is assumed that that the shoes of sacheonwang on Buddhist paintings in Joseon dynasty were hwa implies that the role of tutelary god was stressed in the disordered society.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.10-17
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• 2018

POU (point of use) scrubbers were applied for the treatment of waste gases including PFCs (perfluorocompounds) exhausted from the CVD (chemical vapor deposition), etching, and cleaning processes of semiconductor and display manufacturing plant. The GWP (global warming potential) and atmosphere lifetime of PFCs are known to be a few thousands higher than that of $CO_2$, and extremely high temperature more than 3,000 K is required to thermally decompose PFCs. Therefore, POU gas scrubbers based on the thermal plasma technology were developed for the effective control of PFCs and industrial application of the technology. The thermal plasma technology encompasses the generation of powerful plasma via the optimization of the plasma torch, a highly stable power supply, and the matching technique between two components. In addition, the effective mixture of the high temperature plasma and waste gases was also necessary for the highly efficient abatement of PFCs. The purpose of this paper was to provide not only a useful technical information of the post-treatment process for the waste gas scrubbing but also a short perspective on R&D of POU plasma gas scrubbers.

• Journal of the Korean Geophysical Society
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• v.3 no.3
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• pp.161-174
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• 2000

Bayesian inversion is a stable approach to infer the subsurface structure with the limited data from geophysical explorations. In geophysical inverse process, due to the finite and discrete characteristics of field data and modeling process, some uncertainties are inherent and therefore probabilistic approach to the geophysical inversion is required. Bayesian framework provides theoretical base for the confidency and uncertainty analysis for the inference. However, most of the Bayesian inversion require the integration process of high dimension, so massive calculations like a Monte Carlo integration is demanded to solve it. This method, though, seemed suitable to apply to the geophysical problems which have the characteristics of highly non-linearity, we are faced to meet the promptness and convenience in field process. In this study, by the Gaussian approximation for the observed data and a priori information, fast Bayesian inversion scheme is developed and applied to the model problem with electric well logging and dipole-dipole resistivity data. Each covariance matrices are induced by geostatistical method and optimization technique resulted in maximum a posteriori information. Especially a priori information is evaluated by the cross-validation technique. And the uncertainty analysis was performed to interpret the resistivity structure by simulation of a posteriori covariance matrix.

• Nuclear Engineering and Technology
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• v.28 no.2
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• pp.137-149
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• 1996

The present study is to analyze an integral test, BETHSY test 6.9c, which represent loss of RURS accident under mid-loop operation. Both the pressurizer manway and the steam generator outlet plenum manway are opened as vent paths in order to prevent the system from pressurization by removing the steam generated in the core. The main purposes are to gain insights into the physical phenomena and identify sensitive parameters. Assessment of capability of CATHARE2 prediction can be established the effective recovery procedures using the code in an actual plant. Most of important physical phenomena in the experiment could be predicted by the CATHARE2 code. The peak pressure in the upper plenum is predicted higher than experimental value by 7 kPa since the differential pressure between the pressurizer and the surge line is overestimated. The timing of core uncovery is delayed by 500 seconds mainly due to discrepancy in the core void distribution. It is demonstrated that openings of the pressurizer manwey and the steam generator manway can prevent the core uncovery using only gravity feed injection. Although some disagreements are found in the detailed phenomena, the code prediction is considered reasonable for the overall system behaviors.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.261-266
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• 2001

Effects of elevated carbon dioxide ($CO_2$) on soil microbial processes were studied in a northern peatland. Intact peat cores with surface vegetation were collected from a northern Welsh fen, and incubated either under elevated carbon dioxide (700 ppm) or ambient carbon dioxide (350 ppm) conditions for 4 months. Higher algal biomass was found under the elevated $CO_2$ condition, suggesting $CO_2$ fertilization effect on primary production, At the end of the incubation, trace gas production and consumption were analyzed using chemical inhibitors. For methane ($CH_4$ ), methyl fluoride ($CH_3F$) was applied to determine methane oxidation rates, while acetylene ($C_2H_2$) blocking method were applied to determine nitrification and denitrification rates. First, we have adopted those methods to optimize the reaction conditions for the wetland samples. Secondly, the methods were applied to the samples incubated under two levels of $CO_2$. The results exhibited that elevated carbon dioxide increased both methane production (210 vs. $100\;ng\;CH_4 g^{-1}\;hr^{-1}$) and oxidation (128 vs. $15\;ng\;CH_4 g^{-1}\;hr^{-1}$), resulting in no net increase in methane flux. For nitrous oxide ($N_2O$) , elevated carbon dioxide enhanced nitrous oxide emission probably from activation of nitrification process rather than denitrification rates. All of these changes seemed to be substantially influenced by higher oxygen diffusion from enhanced algal productivity under elevated $CO_2$.

• Journal of The Korean Association of Information Education
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• v.11 no.4
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• pp.447-459
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• 2007

Recently, the use of computer game by Korean teenagers is rapidly growing due to the expansion of the computer popularization and the development of game industry. Of all the teenagers, 82.4% have experience of playing computer game and statistics shows that 22.4% of them play everyday. There is an opinion that the computer game not only improves self confidence and concentration but also enhances internet use, foreign language usage and cognitive ability so that it accelerates learning efficacy and releases stress. On the other hand, there also exists a negative opinion on the symptoms of its addiction. Young(1996) warns that like other addictions, computer game addiction can provoke social problems such as loss of control, desire, marriage problem, schoolwork failure, financial deficiency and loss of employment. Therefore, this study has investigated how computer game addiction affects teenagers' personality. For this purpose, I have conducted the research on the reality of teenagers'computer game use, computer game addiction assessment, analysis on the difference between male and female, and on the relation between the level of computer game addiction and teenagers' personality. As a result, it is confirmed that the computer game addiction affects negatively to teenagers' personality such as stability, self-controlling, perceiving emotion, expressing emotion and controlling emotion.

• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.723-730
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• 2000

Orthodontic tooth movement requires remodelling of periodontal tissues, especially alveolar bone. Fluoride is known to be a potent inhibitor of osteoclastic bone resorption. The purpose of this study was to examine the effects of a consumption of fluoride on osteoclast numbers appearing on the pressure side of alveolar bones at experimental tooth movement. 40 male rats were exposed to 0, 10, 25 mg/kg/day of sodium fluoride(NaF) in their drinking water for up to 60 days. Orthodontic appliance were activated to mesially tip maxillary first molar with 50-70g. The rats were sacrificed at 1, 2, 4 days after initial activation. The number of osteoclast was counted in a $450\times700\;{\mu}m^2$ area interradicular septum on the pressure side of the maxillary first molar. The results were as fellows, 1. There was significantly different osteoclast number between control group and 25 mg/kg/day group at all measured time. (p<0.05) 2. There was significantly different active bone-resorption area between control group and 25 mg/kg/day group except at 96 hours post activation. (p<0.05) 3. There was slight reduction of active bone- resorption area in control group from 48 hours to 96 hours but in both 10 mg/kg/day group and 25 mg/kg/day group a slight increase was observed from 48 hours to 96 hours.

• Journal of Periodontal and Implant Science
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• v.27 no.4
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• pp.819-828
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• 1997

The purpose of this study was to evaluate the abrasion-resistance of root surface after NaF iontophoresis, Nd:YAG laser irradiation and combined treatment 50 anterior teeth with flat interproximal root surface that had been extracted due to periodontal destruction were selected. All teeth were treated by the same procedure as conventional periodontal root treatment, such as scaling and root planing, root conditioning with tetracycline HCI(lOOmg/ml, 5min). The pre-treatment weight of each tooth was measured by a dial scale(SHIMADEU Co, LIBROR EB-220HU, capacity 220.000 g, Japan). All teeth were divided into 5 groups as follows: Nd:YAG laser irradiation(group 1, 1 W, 100 mJ, 10Hz, fiberoptic-root surface distance=5mm, $10\;sec.{\times}6times$, EL.EN.EN060, Italy): NaF iontophoresis(group 2, $150{\mu}A$, 4 min}: Nd:YAG laser irradiation following NaF iontophoresis(group 3): NaF iontophoresis following Nd:YAG laser irradiation(group 4): No treatment(control group). Electric toothbrushing (Oral-B, Brown Co, Germany) was conducted during 1 hour($lO\;min.{\times}6\;times$). Subsequently post-treatment weight was remeasured by the same method as pre-treatment weight measurement. The difference of abrasion rate among all groups was statistically analyzed by ANOVA(SAS program). Following results were obtained: 1. The abrasion rate was significantly lower in Nd:YAG laser irradiation group than NaF iontophoresis group(p < 0.001). 2. The abrasion rate was significantly lower in combined groups of Nd:YAG laser irradiation and NaF iontophoresis than either Nd:YAG laser irradiation group or NaF iontophoresis group(p < 0.001). 3. There was no significant difference in abrasion rate according to application order in the combined groups(p > 0.05). 4. The abrasion rate was significantly lower in all experimental groups than control group(p < 0.001). The results suggest that combined treatment of Nd:YAG laser irradiation and NaF iontophoresis on exposed root surface after periodontal therapy can enhance the abrasion-resistance of root surface and may inhibit the root caries development.

• Journal of the Korean Society of Costume
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• v.22
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• pp.205-224
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• 1994

It was aimed to study the costume of Koryo dynasty based upon the thirty pictures of Bud-dha to hang on the wall among the existing Buddist paintings. The costume to study were made about 64 years during the King Chung-yol(1286) to the King Chung-jong(1350) which style was mostly related in Won Dynasty. 가) Men's wear ; 1. Hair style and hair dress ; Man tied up a top knot and they put on the hat such as a Kuan Kun and Mo. The young boys binds his hair up one, two, and three knot-s, and tied up with a hair ribbon, A kinds of Kuan-mo were Mine-lu-kuan Yuan-yu-kuan, Nong-kuan, Hae-chi-kuan Pok-du Yun-wha-kuan Yip-mo- and Tu-ku(Helmeto) 2. clothes ; 1) Colour of Koryo King's Mien-ku Kuan costume was not agree with blue and reddish black colour which was used in Yo, Song, Kum and Won Dynasty, however black and greenhish blue colour was agreed with. 2) The king wore T'ung-t'ien-kuan(Yuan-yu-kuan) and the government officials wore Chin-hien-kuan Hae-chi-kuan and Nong-kuan as a court dress. In general the king and the Crown Prince wore a hats which was used in T'ung-t'ien system however sometimes they wore small hats which was cited in literature. 3) Gate guard and upper garment wore colourful costume figured gold colour pattern which was distin-gtive costume system of Koryo. 4) A monk wore big sleeve long skirt big sleeve long jacket long skirt and shoulder scar-f full shoulder scarf or right hand shoulder opened scarf. 5) The Soldiers wore helmet shoulder or scarf pee-back hung-kap, pok-kap, yang-dan-g-kap we-yu-kap kun-kap, and boots and they carried arms. 6) The young boys wore scarf, loin cloth, long skirt, belt neckless, wan-silk, boots and foots wear and wristless. 나) Women's wear ; 1. Hair style and hairs and tied up with a hair ribbon and wore precious ston decorated hair dress wheel shape hair dress pan shaped head dress handkerchif covered hair dress decorated precious stone hair pin silk chippon made of head dress muf-fler shaped hairdress. Boots mocasin hae lee, suk and sandle wored as a shoes depends on the classes. They wore neckless, earing wres-tless and wan-pu-sik. 2. Closthe 1) High rank lade's wore un-kyun attached jacket and jacket sleeves decorated pleats and pleats decorated long skirt apron back apron knot belt, scarf this type is the same with Dang Dynasty five dynasty of china Song, Kum Won, Myung Dynasty and our cos-tume of Poe-hae, and Shilla Dynasty.