• Journal of Obesity & Metabolic Syndrome
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• v.25 no.3
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• pp.138-148
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• 2016

Background: The purpose of this study is to analyze the effects of an abdominal obesity management program in middle-aged women in Korea. Methods: Examination of databases, including the Research Information Sharing Service, Database Periodical Information Academic, and Korean Studies Information, resulted in identification of 772 studies performed up to 2014, of which 43 satisfied the inclusion data. Data analysis was performed using R version 3.2 to calculate the effect sizes, explore possible causes of heterogeneity, and check for publication bias, using a funnel plot and its trim-and-fill analysis. Results: The mean effect size of the management program was small (g=0.22), along with the anthropometric index (g=0.18), metabolism index (g=0.21), fat-distribution (g=0.36), and inflammatory index (g=0.36). Moderator analysis was performed to determine heterogeneity, but no significant differences were found between the randomized controlled trial (RCT) group and non-RCT group. In addition, the length of the session was found to be statistically significant after performing a meta-regression. Finally, a funnel plot with a trim-and-fill analysis was produced to check for publication bias, but no significant bias was detected. Conclusion: Based on these findings, the abdominal obesity management program affects middle-aged women in Korea. Further research is needed to target other age groups with abdominal obesity.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.136.1-136.1
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• 2010

고체산화물 연료전지(SOFC)에서 사용되는 연결재의 주 기능은 각 단위 셀의 연료극과 다음 셀의 공기극을 전기적으로 연결하여, 공기와 사용연료의 분리역할을 하기위해 사용된다. SOFC용 연결재는 다른 구성요소 소재보다 높은 전기전도성, 낮은 이온전도성이 요구되며 SOFC는 고온에서 작동되기 때문에 다른 구성 소재들과 유사한 열팽창계수와 물리, 화학적인 안정성이 요구된다. 현재 연결재 제조기술은 plasma coating, sputtering, screen printing, 전사법등 다양한 연구가 진행되고 있다. 본 연구에서는 저렴한 비용으로 대량생산이 용이한 고상반응법을 적용하여 세라믹연결재를 제조하고, 그 특성을 연구하였다. 세라믹 연결재로서 선정한 합성조성은 $(La_{0.7}Ca_{0.3})(Cr_{0.9}Co_{0.1})O_3$로 SOFC 작동온도에서 높은 전기전도도를 나타낸다. LCCO 연결재를 1300, 1400 및 $1500^{\circ}C$에서 합성을 진행하였을 때 출발원료로 $CaCO_3$를 $CaF_2$로 대체하였을 때의 소결특성을 평가하였고, SEM과 XRD분석을 통하여 균질하고 결정성이 우수한 분말이 합성된 것을 확인하였고 DC impedance analyzer를 사용하여 전기전도도를 측정하였다. TMA를 사용하여 열팽창계수를 측정한 결과 YSZ(${\sim}10.8{\times}10^{-6}/^{\circ}C$)와 동일한 값을 나타내었다.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.76-83
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• 2017

Biogas, combine with ever-increasing natural gas demand, has been on the center stage in South Korea for the early part of twenty first century in an effort to reduce the emission of global warming gases. With the passage of legal system of City Gas Business Law in 2014, the biogas has its place of production and distribution to consumers. However, it has a room for its technological improvements in terms of enrichment, by separating carbon dioxide and removing impurities efficiently. For these improvements, four different methane enrichment processes were tested in this study; membrane separation, water absorption, Chemical Absorption and Adsorption. A variety of operation scenarios were applied to the processes and the best practices were drawn out. The optimum process was selected based on case study results. Methane produced in this study showed 97% purity and 98% recovery rate, which meets the requirements of the City Gas quality standards.

• Journal of Korean Society of Transportation
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• v.32 no.4
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• pp.389-400
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• 2014

This study finds a way to increase the usability of a subway commuter pass. Usability of the commuter pass on a probabilistic statistical model is calculated when the pass is allowed to used in a different mode(bus). A sunk cost of commuter pass is used to reduce the vehicle travels from public transit. 324 people aged 25 to 35 were surveyed and utilized to build a Nested Logit Model on STRADA 3.5 platform. Main results are as follows. First, commuter passes were issued in various forms. Second, the model turns out to be statistically significant in four explanatory variables (discount rate, inter-usablity between modes, forms of payment and periods). Lastly, the more valid on different modes, the more increased of the rail commuter pass.

• Journal of Preventive Medicine and Public Health
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• v.36 no.1
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• pp.71-76
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• 2003

Objectives : New organizational work systems, and their impact on the mental health of employees, are considered to beone of the most important topics in the area of industrial health. This study was conducted to compare job characteristics (job demand and decision latitude) levels, and psychosocial distress of workers in acompany introducing to new organizational work systems, to those of workers managed by traditional work systems. Methods ; A study sample of 627 shipbuilding workers (446the new work organizational system and 181 the traditional system) were recruited for this study. A structured-questionnaire was used to assess general characteristics, job characteristics(work demand, decision latitude), and psychosocial distress. Results : The decision latitude was not significantly higher in the new work system compared to the traditional system. However, the job demand was significantly higher in the new work system than in the traditional system. The psychosocial distress was higher within the new work system than the traditional system, but no significant relationships were found. The proportion of increased strain was significantly greater with the new system than the traditional system. Conclusion : These results suggest that increases in the decision latitude did not sufficiently compensate for higher job strain or increased work intensity. If the increase in the decision latitude was temporary, with the typical job demand remaining high, such work can be still be considered to have a job strain Futureresearch should consider psychosocial distress and fatigue as importantproblems caused by new work organizational systems, and should be performed to assess their impact through out industry.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.2
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• pp.27-39
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• 2000

Objectives : The purpose of this study is to analyze the factors associated with respirator usage on the basis of reasoned action theory. Methods : The data were collected from August 1 to September 30 1999, and study subjects consisted of 303 workers who were employed in the manufacturing industries. A self-administered questionnaire was used to measure the attitude, subjective norm and related factors. Results : In bivariate analysis, the variables related to protector usage were prevention of occupational disease, protection of toxic material, disturbance during working, troublesome of usage, proper exchange of protector. Multivariate logit analysis was used to estimate factors associated with respirator usage. Significant predictors that are related to respirator usage were attitude toward the behavior, size of industry and proper exchange of protector. Conclusions : The results suggest that it is strongly required to focus on attitude toward the behavior in order to improve workers' usage of respirator.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.406-409
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• 2004

A blue phosphor(ZnS:Cu) is manufactured by solid state reaction for ACPEL(AC powder EL). The effect of artificial defect on phosphor surface on the ZnO phase conversion and resulting luminescence have been studied. It was found that ZnS:Cu could converse to cubic phase more easily due to the formation of artificial defect on 1st fired phosphor by ball-milling process, resulting in improvement of luminescence of phosphor phosphors under the driven EL condition. We found out an optimized ball-mill condition through considering effect of each ball-mill conditions such as milling time and milling rpm on defect. Also we determined relationship between emission luminescence and phase of phosphor based on analyses of crystal structures of phosphors. A significant improvement above 30% was observed in electroluminescence by the artificial defect on ZnS:Cu phosphors compared to non-treated phosphors.

• Journal of Korean Society on Water Environment
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• v.32 no.6
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• pp.600-627
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• 2016

Korea is one of the countries with a large veterinary antibiotics market, although antimicrobial resistance in bacteria is becoming a serious issue in many countries. The Korean government started to take interest in estimating the effects of livestock manure on rivers and agricultural soils and in monitoring of heavy metals, organic pollutants and antibiotics in the ambient water and soil. In this paper, pre-treatment methods to separate the selected antibiotics from solid samples were reviewed. It is essential to select an efficient and appropriate procedure for pre-treatment due to the high proportion of proteins and organics in biosolid samples. Pre-treatment consists of extraction followed by clean-up. Initially, homogenized samples were extracted by sonication, mechanical agitation or pressurized liquid extraction with methanol/acetonitrile/water mixture under acidic/basic conditions depending on the compound. However, aminoglycosides and colistin were extracted with 5% trichloroacetic acid and HCl, respectively. Since the ${\beta}-lactams$ are easily decomposed in acidic and basic conditions, they were extracted in neutral pH. Filtration with a membrane (pore size, $0.2{\mu}m$) or solid phase extraction with HLB and methanol, as eluents, was normally applied for the clean-up. At least, three different pre-treatment procedures should be adopted to screen all the selected antibiotics in solid samples.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.745-752
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• 2020

A numerical study was carried out to evaluate the aerodynamic characteristics of the supersonic grid fins installed on SpaceX Falcon 9. The unit-grid-fin concept was utilized for more efficient and simpler 3-D steady flow calculations. Pre- and post-correction processes that accounted the interference effects by the angle of attack of the missile, the influences of the outer frame of the grid fin and the connecting rods were improved in the study, and it was demonstrated that the present correction method was more accurate as compared to previous studies. Finally, the present approach was applied to evaluate the aerodynamic characteristics in transonic/supersonic flights of SpaceX Falcon 9 with various angle of attacks.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.1000-1005
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• 1997

The properties of ceramics by solid-state reaction with hydroxyapatite[$Ca_{10}(PO_4)_6(OH)_2$], which was isolated from tuna bone by wet milling process were investigated. The bulk density $2.93g/cm^3$ at $1350^{\circ}C$ was close to the calculated density $3.21g/cm^3$. On X-ray measurements, the major phases were identified as hydroxyapatite at below $1300^{\circ}C$, but the whitlockite [$Ca_3(PO_4)_2$] phases were appeared due to a decomposition of hydroxyapatite with temperature. The microstructures of sintering specimens were shown as small closed pores between grain boundaries. The mean bending strength of the sintered hydroxyapatite by solid-state reaction is about 58 MPa and this value is higher than that of the articular cartilage maximum strength, 40MPa.