• 대한기계학회논문집
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• 제14권2호
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• pp.430-439
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• 1990

Steady state turbulent airflow and unsteady characteristics of generation, transportation, and recovery behavior of contaminate particles in the simplified 2 dimensional Vertical Laminar Flow (VLF) type clean room was numerically simulated using the low Reynolds number k-over bar.epsilon- turbulent model. Characteristics of airflow in VLF type clean room are greatly affected by the recirculation zone around working surface. The recirculation zone must be considered at the time of clean room design because the recirculation zone whose area increases with increment of inlet velocity exerts bad influence upon the performance of clean room in terms of particle contamination. The location of maximum particle concentration changes from the location of particle source to the recirculation zone, while averaged particle concentration is reduced exponentially with time. Recovery time of clean room with spontaneous particle generation source is inversely proportional to inlet velocity. We introduce nondimensionalized recovery time through the dimensional analysis, which can indicates the general performance of clean room with design structure change. It was identified that .tau. is independent of inlet velocity and background concentration. Therefore .tau. can be the simple factor to compare the different structure of clean room in terms of dynamic response to contamination and becomes larger with better structure of clean room.

• The Journal of Asian Finance, Economics and Business
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• 제7권6호
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• pp.19-27
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• 2020

This research investigates the determinants of investment capital size in Vietnam's small and medium-sized firms. The study employs a sample of 458 small and medium-sized enterprises in the country. The study is based on data collects in the areas of Hanoi, Bac Can, Buon Ma Thuot and Pleiku Provinces at time series data of October 2019. This study also identifies the factors that affect the size of investment capital in medium and small-sized enterprises in Vietnam. Data are processed via STATA 14.0 and SPSS 20.0 software. The research results indicate that (1) business lines, (2) import and export business, (3) type of business registration, (4) business location, (5) operating time, and (6) the percentage of the organization's capital contribution are factors that impact on the size of the investment capital of the business. Business line and business location have negative impacts on investment capital size. The operating time, the percentage of the organization's capital contribution, import and export business, and the type of business registration have positive impacts on investment capital size. In addition, the findings of this study also suggest that the operation time has the highest impact on investment capital size of the small and medium-sized firms in Vietnam.

• 보건행정학회지
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• 제18권2호
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• pp.67-85
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• 2008

This study evaluated the specialization status of Korean hospitals by applying index measures that were developed to determine how hospitals are specialized. In addition, multivariate regression analysis was applied to assess how the measures responded to the internal and external factors of hospitals. National Health Insurance claims for 2004 were used to calculate the information theory index, internal Herfindahl index, number of distinct diagnosis-related groups (DRGs) treated, and percent of the five most common DRGs. Data from the Ministry of Health and Welfare and Korean Hospital Association were used to determine the size, ownership, teaching status, organization type, and location of the hospitals. The four indexes analyzed showed that there were significant differences in the specialization status of providers, depending on the provider size, organization type, and location. Hospitals that were smaller and located in metropolitan areas tended to provide specialized services; this is considered to constitute a competitive strategy for hospitals. It is expected that specialized hospitals will increase given the current market structure. Therefore, policy makers will need an index for measuring how hospital services are specialized. Information from such an index could provide a picture of how hospital services are mixed and change over time.

• 상하수도학회지
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• 제26권4호
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• pp.521-533
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• 2012

Interest in application of ultraviolet light technology for primary disinfection that used for the treatment of water for consumption and wastewater has increased significantly in recent years. Analysis of these systems has been carried out using Computational Fluid Dynamics (CFD) procedure. It offers advantages over other techniques in specific circumstances. CFD has emerged as a powerful tool to aid design of a UV reactor by providing the UV dose delivered by the proposed reactor design and allowing engineers to evaluate alternative designs in much less time and at a reasonable cost. In this study, five different configurations of the apparatus depending on the location of the exit are evaluated in terms of maximum dose, minimum dose, flow patterns, particle tracks and transient dose. The configuration 3 results have higher minimum UV dose value and uniform particle distribution of the UV dose on the outlet than other's.

• 가정과삶의질연구
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• 제24권6호
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• pp.47-60
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• 2006

The purpose of this study was to find out which factors can affect customer satisfaction in the life insurance industry. Specifically, it was designed to investigate whether there were significant differences in the perceived service quality according to demographic characteristics to investigate whether there was a significant relationship between each service quality type and consumer satisfaction and to investigate whether the location in demographic characteristics serves to moderate the links between the perceived service quality and customer satisfaction. Data were collected from insurance subscribers living in Seoul and the Gyeonggi-do area and 364 questionnaires were taken into account in the analysis. Major findings of this study were as follows: First, there were significant differences in the perceived service quality according to demographic characteristics. Second, there were significant differences in customer satisfaction according toeach service quality type. Finally, the location in demographic characteristics did serve to moderate the links between the perception of service quality and customer satisfaction.

• 한국지진공학회논문집
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• 제18권4호
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• pp.161-170
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• 2014

Newmark-type deformation analysis has rarely been done in Korea due to the popularity of simple pseudo-static limit equilibrium analysis and detailed time-history FE/FD dynamic analysis. However, the Korean seismic dam design code updated in 2011 prescribes Newmark-type deformation analysis as a major dynamic analysis method for the seismic evaluation of fill dams. In addition, a design PGA for dynamic analysis is significantly increased in the code. This paper aims to study the seismic evaluation of four existing large fill dams through advanced FEM/Newmark-type deformation analyses for the artificial earthquake time histories with the design PGA of 0.22g. Dynamic soil properties obtained from in-situ geo-physical surveys are applied as input parameters. For the FEM/Newmark analyses, sensitivity analyses are performed to study the effects of input PGA and $G_{max}$ of shell zone on the Newmark deformation. As a result, in terms of deformation, four fill dams are proved to be reasonably safe under the PGA of 0.22g with yield coefficients of 0.136 to 0.187, which are highly resistant for extreme events. Sensitivity analysis as a function of PGA shows that $PGA_{30cm}$ (a limiting PGA to cause the 30 cm of Newmark permanent displacement on the critical slip surface) is a good indicator for seismic safety check. CFRD shows a higher seismic resistance than ECRD. Another sensitivity analysis shows that $G_{max}$ per depth does not significantly affect the site response characteristics, however lower $G_{max}$ profile causes larger Newmark deformation. Through this study, it is proved that the amplification of ground motion within the sliding mass and the location of critical slip surface are the dominant factors governing permanent displacements.

• 가정과삶의질연구
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• 제16권3호
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• pp.95-110
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• 1998

The purpose of this study was to analyze contributing factors to the perception of elderly's residential problems and satisfaction. The sample in this study consisted of 556 elderly husband and wives over 55 years old living in Seoul Daejeon Jeonju and Daegu. Statistics employed for the analysis were frequencies means one-way anova and umltiple regression analysis. The results could be summarized as follows. Deficiency of privacy was the worst status and then noise and air-pollution and the level of facilties in residential space. And the perception of residential problems could be affected by age health the type of family the number of family the ownership of house the type of house location and the economic status The significant variable positively related to the residential satisfaction were the healthy conditon of eldely ownership of house living in multihousing the perception of privacy and high level of facilities in the house.

• International journal of advanced smart convergence
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• 제11권3호
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• pp.162-169
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• 2022

The purpose of this study is to estimate the determinants of the smoking demands of university students. For this study, a total of four four-year universities and two-year colleges in Seoul and provincial areas were surveyed. The model for analyzing the demand for smoking was applied with a double hurdle model, and determinants to participate in smoking in the first stage and the amount of smoking in the second stage were analyzed. According to the analysis results, the determinants to participate in smoking as a first stage are gender, grade, college type, major category, and parents' income, which have a statistically significant effect, and the analysis of the amount of smoking as a second has been analyzed as the variables that influence gender, grade, college location, major, parents' income type and income amount.

• Journal of the Korean Wood Science and Technology
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• 제18권3호
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• pp.42-52
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• 1990

In this study, thick 24mm glulams were composed of thick. 3, 4, 6, 8mm Larch laminas to study that the theoretical analysis and the experimental analysis regarding the location of neutral axis of the glulams were compared, and to study on the effect of location of neutral axis on mechanical properties of glulam. The variation of location of neutral axis after proportional limit(or elastical limit) was studied to offer basic data to make the better composition method of glulam. The result obtained can be summarized as follows: 1. The theoretical neutral axis was 0.547 in solid wood, and also 0.547 in glulams because glulams were composed of only Larch laminas. 2. In solid wood, the deviation of the theoretical and the experimental neutral axis location was 0.1%, But in glulams, the deviation from-12.2% to + 7.8% showed nonuniform pattern but no large deviation. Because laminas was only of Larch and so the mechanical properties of laminas were monotonous. 3. The neutral axis exerted no influance on the elasticity of glulam, which meaned that the maximum shear strength in the neutral axis showed no influance on elasticity limit. 4. The only minutely lower elasticities of glulam than that of solid wood were shown. This was because of influance of glue lines of glulam on the elasticlties. 5. The failure type of glulam was wholly simple tension failure and the horizontal shear failure near neutral axis was not taken place, which was that glue line was complete in bonding and the strength of the lamina was not various but uniform. 6. The ratio of tension strain($^{\varepsilon}t$) I compression strain($^{\varepsilon}c$) initially showed uniform level After the elasticity limit. the ratio was increased with the flow of time and so the tension strain was more increased than compression strain. So this proved tension lamination technique, which is that the mechanical properties of glulam could be improved, if the lamina of more superior strength would he added on the bottom side of the glulam.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.597-602
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• 2007

It is proposed to analyze the vibration of slab with MTMD and vibration-induced noise. Substructure synthesis is introduced to develope the interaction between the slab and MTMD which are defined in different space and acoustic power is obtained from the velocity field of slab. Numerical analysis is performed to show that the vibration and noise of slab can be reduced by MTMD. A living room of wall type apartment including the wall and MTMD is modeled and analyzed by FEM program Numerical analysis shows that the vibration and noise control effect is different depending on the location and mass ratio of MTMD. Futhermore, noise is more effectively reduced when the vibration of higher modes of slab are reduced rather than lower modes.