• Membrane Journal
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• v.6 no.3
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• pp.173-181
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• 1996

Common volatile organic compounds(VOCs) such as toluene and methanol were removed successfully from N$_{2}$ using a novel silicone-coated hollow fiber membrane module. This novel membrane is a thin film composite(TFC) and was highly efficient in removing VOCs selectively from a N$_{2}$ stream. This membrane had some innate advantages over other silicone-based membrane in that the selective barrier was ultrathin(~1 $\mu$m) and the porosity of the polypropylene substrate was high which leads to a low permeation resistance. The substram was very strongly bonded to the coating layer by plasma polymerization and can withstand a very high pressure. A small hollow fiber module having a length of 25cm and 50 fibers could remove 96~99% of toluene as well as methanol vapors when the feed flow rate was up to 60cc/min. The percent removal of VOCs were even higher when the feed inlet concentration was higher. This process is especially suitable for treating streams having a low flow rate and high VOCs concentration. The permeances of VOCs through this membrane was in the range of $4~30 \times 10^{-9}gmol/sec \cdot cm^{2}\cdot cmHg$ for both toluene and methanol, and nitrogen permeance was between $3~9 \times 10^{-10}gmol/sec \cdot cm^{2} \cdot cmHg$. High separation factor between 10~55 for toluene/N$_{2}$ and 15~125 for methanol/N$_{2}$ were obtained depending on the feed flow rate ranges and feed VOCs concentration levels.

• Korea journal of population studies
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• v.21 no.2
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• pp.5-36
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• 1998

This study examines the change of female labor market structure during the last several decades, focusing the effects of demographic factors such as declining fertility and increasing educational attainment of women. Women of the recent cohort tend to postpone their first marriages, to attain higher levels of education, and to have smaller number of children than women of the old cohort. This demographic trend results in the change of the population compositions in a way that population subgroups with high labor force participation have been increased. In addition, women of each population subgroup supply their labor in the market with higher rate than their old cohort counterparts. The labor force participation rate of highly educated women, and of married women has been increased faster than that of women with low education and of unmarried women. Although childbirth is still one of the most critical barrier for the women's participation, more and more women with young children tend to work for pay than ever before. In spite of the demographic change which is supportive to the increasing labor force participation, the Korean labor market have lost its female participants for the last year of the economic restructuring, reflecting demand-side factors as well as demographic factors are essential to determine the labor force participation of women.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.2
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• pp.111-116
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• 2018

In cosmetics market, anti-pollution products recently come up with new solution for skin health. Environmental oxidation mechanisms are realized as bio-marker of atmospheric pollution upon skin by environmental pollutant such as ozone, UV rays, particulate matter (PM) as well as cigarette smoke. The exposure of cigarette smoke directly or indirectly causes the oxidation of the stratum corneum skin lipids, resulting in the conversion of squalene to squalene monohydroperoxide and/or generation of malondialdehyde (MDA) as a product of lipid peroxidation. The aim of this study is to see whether new cosmetics product containing red beet has anti-oxidation effect on skin exposed by cigarette smoke. So as to determine oxidative damage to human skin at biochemical level, each unit area of volar forearms was exposed to cigarette smoke through device (3.3 cm, diameter) for fifteen minutes, then measured MDA using standardized TBARS assay kit. Compared to negative control (untreated and unexposed area), the level of MDA was significantly increased at positive control (untreated and exposed area) more than 3.7 times, indicating the pollutant induced-oxidative damage on the skin barrier. Whereas, the pre-applied area with the cosmetics products containing red beet revealed a decrease of 25% compared with positive control. As reports, these data demonstrated that cigarette smoke induce peroxidation of stratum corneum skin lipids. Conclusively, we suggest that anti-pollution effect of the cosmetics product containing red beet is beneficial to prevent the oxidation of skin lipids by atmospheric pollution.

• Journal of dental hygiene science
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• v.9 no.4
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• pp.405-412
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• 2009

The purpose of this study investigated the effect of Au coating on adhesion between porcelain matrix and metal substructure interface. Titanium, Ni-Cr alloy and Co-Cr alloy are well known as proper metal for the dental restorations. The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. However, adhesion between dental alloys and porcelain is related to diffusion of oxygen during ceramic firing. The excessive oxidized layers make hard adhesion between dental alloy and ceramic. Ni-Cr and Co-Cr specimens were divided into test and a control group and Titanium specimens were divided into three test groups and a control group. Each group had 20 specimens. The adhesion characteristics of porcelain and metal with Au coating layer and without Au coating layer were observed with scanning electron microscopy(SEM). The adhesion was evaluated by a biaxial flexure test and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that Au coating layer is effective barrier to diffuse oxide layer completely protect non-precious alloys from oxidation during the porcelain firing. The SEM photomicrographs of cross-section specimens showed a smooth interface between Au coating layer and metals and porcelain which suggested proper chemical bonding, and no gap, porosity were observed. The mode of failure was mainly adhesive for Ti tested specimens, but mixed failures with adhesive and cohesive were observed in Ni-Cr and Co-Cr specimens. The adhesion between non-precious metals and porcelain would not be improved by Au coating agent. However, It is suggested that the continuous study is required further investigation and development.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.4
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• pp.304-312
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• 2011

Grain size analysis was conducted for a total of 402 surface sediments collected from 67 sites along three (upper, middle, and lower) transects corresponding to the high-, mid-, and low-intertidal zone of beach on the Sinjado, Nakdong River estuary in Nov. 2005 and May 2006. Sinja-do beach sediments showed uni-modal grain size distributions, in which the mode of $3.0{\phi}$ was dominant in 2005 whereas the mode of $2.5{\phi}$ in 2006. This coarsening trend was more remarkable in the western side of beach as well as in the mid- and low-intertidal zone. In this study, we focused on investigating characteristics of sediment size changes on the basis of transect data that differ in tidal elevation. For this purpose, a statistical test was applied for transect by transect comparison of grain size parameters such as mean, sorting, and skewness. Mean values between middle and lower transect, sorting values between upper and lower transect, and skewness values over the beach reflected statistically significant temporal changes. Also, mean and skewness parameters showed an inverse relationship which was more stronger in 2006 than in 2005. Temporal changes in Sinja-do beach sediments resulted in decrease of mean and sorting values but increase of skewness values, intensifying the inverse relationship between mean and skewness parameters.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.535-542
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• 2015

A reactor containment acts as a final barrier to prevent leakage of radioactive material due to the possible reactor accidents into external environment. Because of the functional importance of the containment building, the SIT(Structural Integrity Test) for containments shall be performed to evaluate the structural acceptability and demonstrate the quality of construction. In this paper, numerical analyses are presented, which simulate the results obtained from the SIT for a prestressed concrete(PSC) structure. A sophisticate structural analysis model is developed to simulate the structural behavior during the SIT properly based on various preliminary analysis results considering contact condition among structural elements. From the comparison of the analysis and test results based on the acceptance criteria of ASME CC-6000, it can be concluded that the construction quality of the containment has been well maintained and the acceptable performance of new design features has been verified.

• Phonetics and Speech Sciences
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• v.12 no.2
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• pp.29-37
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• 2020

Recently, the neural network-based deep learning algorithm has dramatically improved performance compared to the classical Gaussian mixture model based hidden Markov model (GMM-HMM) automatic speech recognition (ASR) system. In addition, researches on end-to-end (E2E) speech recognition systems integrating language modeling and decoding processes have been actively conducted to better utilize the advantages of deep learning techniques. In general, E2E ASR systems consist of multiple layers of encoder-decoder structure with attention. Therefore, E2E ASR systems require data with a large amount of speech-text paired data in order to achieve good performance. Obtaining speech-text paired data requires a lot of human labor and time, and is a high barrier to building E2E ASR system. Therefore, there are previous studies that improve the performance of E2E ASR system using relatively small amount of speech-text paired data, but most studies have been conducted by using only speech-only data or text-only data. In this study, we proposed a semi-supervised training method that enables E2E ASR system to perform well in corpus in different domains by using both speech or text only data. The proposed method works effectively by adapting to different domains, showing good performance in the target domain and not degrading much in the source domain.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.127-133
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• 1998

An impacted tooth is defined pathologically as a tooth that remains under the mucosa of inside bone without eruption of the crown after a specific period of eruption. Clinically, the term includes those teeth, even before eruption period, that are not expected to erupt due to shape, position and alignment of tooth and lack of space. Canine is prone to impaction more than other teeth because it has the longest time to develop and a complex route from the place of formation to the site of eruption. The impaction incidence of maxillary canine is repoted 0.92$\sim$3.3% (Ferguson, 1990). In 1995 Orton reported that the incidence was 0.92$\sim$2.2% and palatal impaction was more frequent than labial impaction(85%:15%). In 1969 Johnston presented it was more common to woman than to man(3:1). The etiology includes systemic disease such as endocrine disorder, cleidocranial dysostosis, irradiation, Crouzon syndrome, ricketts, facial hemihypertrophy and hereditary and local problems such as ectopic position of the tooth, distance of tooth from its place of eruption, malformation of the tooth, presence of supernumerary teeth, trauma of tooth germ, infection of tooth germ, displacement of tooth germ or tooth by a neoplasm, ankylosis, overretention of deciduous predecessor, lack of space for the tooth in the dental arch and mucosal barrier due to gingival fibrosis. The maxillary canine is especially important as it has the longest root, provides guidance for lateral movement of the mandible and masticatory function and assumes an important role esthetically as it is located at mouth angle. If left untreated, it may cause migration and external, internal resorption of adjacent teeth, loss of arch length, formation of dentigerous cyst or tumors, infection and referred pain as well as malposition of the tooth. Therefore, periodic examination of the development and eruption of the maxillary canine is especially important in a growing child. This case study presents the results of treatment of palatally impacted maxillary canine utilizing surgical exposure and orthodontic tooth movement on patients visiting SNUDH dept. of pediatric dentistry.

• Culinary science and hospitality research
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• v.16 no.4
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• pp.15-27
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• 2010

As most companies in the world are much interested in the overseas market as well as in the domestic market, many Korean food service enterprises came to focus on extending their branches to the overseas market. However, lack of business strategies including market research, marketing strategies, localization, etc. has made them continue to fail in market entry. The purpose of this study is to develop entry mode of determinants of Korean food service enterprises, considering their characteristic factors and environment factors in the overseas market. To do this, companies which have a head quarter in Korea and over 2 year business experience in the overseas market were chosen and used for a self-administered questionnaire survey. Statistical processing, including descriptive statistics, logistic regressing analysis, and multi regression analysis using an SPSS/PC 12.0 statistical package were conducted The result is as follows. First, explanation suitability was 85% of the entry mode in the overseas market. Second, as business size was smaller, product differentiation was higher, and CEO's will for success in the overseas market was higher, independent entry mode in the overseas market was likely to he chosen. Lastly, as the uncertainty of demand and trade barrier were lower, and a sociocultural gap was smaller, independent entry mode in the overseas market was likely to be chosen.

• Journal of Science Education
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• v.33 no.1
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• pp.87-99
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• 2009

The purpose of this study was to evaluate the quality of biology contents of cyber home learning systems which provided by 16 metropolitan and provincial offices of education. The contents were evaluated by the 9 categories: needs assessment, instruction design, learning contents, teaching & learning strategy, interaction, supporting system, evaluation, ethicality and copy right. The result showed that the contents have advantage in detailed learning goal, useful learning environment, learning activities by level, and various learning parts material, but lack in evaluation method tool for personal learning by level and the latest learning material. Based on this results, it is expected that the barrier of the efficient learning contents should be searched for the complement, as well as the development high-quality educational contents and the management of cyber home learning system.