• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.3
• /
• pp.18-25
• /
• 2006

In order to perform system requirements quickly and accurately, an automatic design program of solid rocket motors(SRM) structure designated as the 'ProDes software' has been developed and verified. from given system design criteria and constraints, it has the capabilities to design, analysis, simulation and drawing process to greatly reduce the over 'design cycle time' and manpower of a project. The conception of the program is modular, and calculations are performed step by step allowing parametric design studies and providing final selected design goal. Each configurations of SRM components and joint types composed of various master models is obtained from the data base module of the library. Between the design results of the ProDes software and those of the previous detail design of the established motor showed good agreements.

• Korea journal of population studies
• /
• v.14 no.1
• /
• pp.26-34
• /
• 1991

Migration studies that assume that decision making is done on an individual basis is overlooking the importance of the family factor. Considering that must people belong to families, it is more appropriate to view migration decision from the perspective of the family. This study analyzes the household migration decision whereby the alternatives are to stay, 10 undertake family migration or to undertake single migration of a member. In developing a conceptual model of household migration decision, it is assumed that the household's objective is to maximize household income which is a function of individual members' earnings. The benefits and costs of household migration and individual migration are identified and the household chooses the migration strategy that maximizes expected household income. When household members have conflicting earning prospects in the potential destination, the household considers single migration of the member with the best earning potentials. However, lone migration by a household member involves cost of family separation which is both monetary and psychic, and this study shows that lone migration is undertaken only when its net gains to the family are greater than the separation cost of the family. The major benefit of choosing single migration is the retention of home base in the place of origin which can serve as an insurance against the uncertainty of obtaining a job in the destination, the benefit that is unavailable in family migration. The conceptual analysis shows how a household's migration decision would depend on its members' economic roles and prospects in the destination. Besides the economic variables, social and life cycle variables of the family translate into separation costs and benefits of migration. This study indicates that one - earner family in low economic status but with good earning prospects and high separation costs is more likely to choose family migration over single migration.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.43 no.1
• /
• pp.110-122
• /
• 2020

Many companies make considerable efforts in implementing supply chain management systems to increase their competitiveness. In particular, there are significant investments in their ICT (Information and Communication Technology) and supply chain. However, considerable diversity exists in how well firms have been able to assimilate ICT and leverage the business value of it. In addition, studies on supply chains, particularly Real Time Enterprise (RTE) competence, which is cited for rapid information sharing and dynamic capabilities for each role in the supply chain, are insufficient. The purpose of this paper is to explore and evaluate effect of ICT utilization capabilities, including 'ICT internal cooperative capabilities' and 'ICT operational flexibility capabilities', on RTE capabilities (flexibility, visibility and prediction) and supply chain performance. To validate the research model proposed in the study, survey was conducted on companies using ICT along the supply chain of manufacturing industries. 216 data were used, SPSS and AMOS were used for the analysis methods. Study results showed that ICT internal collaboration capabilities affect agility, one of RTE capabilities, but not visibility and prediction, and ICT operational flexibility capabilities have affected all three RTE capacities. And, RTE capabilities had a huge impact on supply chain performance as expected. In this paper, it has been found that the ICT capabilities in manufacturing are an important factor in improving RTE capabilities that are important in the supply chain and improving the performance of the supply chain.

• Journal of the Korea Safety Management & Science
• /
• v.15 no.1
• /
• pp.109-120
• /
• 2013

As information-oriented industry has been developed and electronic devices has come to be smaller, lighter, multifunctional, and high speed, the components used to the devices need to be much high density and should have find pattern due to high integration. Also, diverse reliability problems happen as user environment is getting harsher. For this reasons, establishing and securing products and components reliability comes to key factor in company's competitiveness. It makes accelerated test important to check product reliability in fast way. Out of fine pattern failure modes, failure of Electrochemical Migration(ECM) is kind of degradation of insulation resistance by electro-chemical reaction, which it comes to be accelerated by biased voltage in high temperature and high humidity environment. In this thesis, the accelerated life test for failure caused by ECM on fine pattern substrate, $20/20{\mu}m$ pattern width/space applied by Semi Additive Process, was performed, and through this test, the investigation of failure mechanism and the life-time prediction evaluation under actual user environment was implemented. The result of accelerated test has been compared and estimated with life distribution and life stress relatively by using Minitab software and its acceleration rate was also tested. Through estimated weibull distribution, B10 life has been estimated under 95% confidence level of failure data happened in each test conditions. And the life in actual usage environment has been predicted by using generalized Eyring model considering temperature and humidity by developing Arrhenius reaction rate theory, and acceleration factors by test conditions have been calculated.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.11 no.2
• /
• pp.782-795
• /
• 2019

Safety is always acritical focus of exploration of ocean resources, and it is well recognized that human factor is one of the major causes of accidents and breakdowns. Our research developed a dynamic human reliability assessment approach, Predicted Mean Vote-Cognitive Reliability and Error Analysis Method (PMV-CREAM), that is applicable to monitoring the cognitive reliability of oceanauts during deep-sea missions. Taking into account the difficult and variable operating environment of manned submersibles, this paper analyzed the cognitive actions of oceanauts during the various procedures required by deep-sea missions, and calculated the PMV index using human factors and dynamic environmental data. The Cognitive Failure Probabilities (CFP) were calculated using the extended CREAM approach. Finally, the CFP were corrected using the PMV index. This PMV-CREAM hybrid model can be utilized to avoid human error in deep-sea research, thereby preventing injury and loss of life during undersea work. This paper verified the method with "Jiaolong" manned submersible 7,000 m dive test. The"Jiaolong" oceanauts CR(Corrected CFP) is dynamic from 3.0615E-3 to 4.2948E-3, the CR caused by the environment is 1.2333E-3. The result shown the PMV-CREAM method could describe the dynamic human reliability of manned submersible caused by thermal environment.

• Journal of the Korean Society for Railway
• /
• v.11 no.3
• /
• pp.216-224
• /
• 2008

In general, based on criteria of subway law, radius 500m from subway station is defined as SIA(Subway Station Influence Area). Therefore, in this paper, selection models of SIA are developed to identify appropriate SIA for recently developed 4 new towns based based on CART analysis. As a result, following outputs are obtained; (1) walking distance from subway station is the most influential factor to define SIA (2) SIAs vary with new towns (i.e., bundang city: 856m, ilsan sanbon city 508m, pyungchon city 495m), and (3) walking distance from subway station is influential to land price of SIA. In addition, bundang and pyungchon new town are more affected in land price and walking distance. Therefore, it is desirable for current definition of SIA (radius 500m from subway station) to reflect characteristics of land use and walking distance in the new towns.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.22 no.2
• /
• pp.132-140
• /
• 1996

The effect of a novel delivery system, water in oil emulsion containing chitosan hydrogel as a inner phase (W/O-C) was evaluated, and the relationships between the skin permeation, the skin primary irritation and the skin turnover rate of AHAs were discussed. We selected glycolic acid (GA), lactic acid (LA), malic acid (MA), and tartaric acid (TA) as model AHAs. The steady state fluxes of 4 AHAs across the excised hairless mouse skin increased as the molecular weights of the AHAs decreased. (GA>LA>MA>TA). The skin turnover times were shortened in all AHAs, compared with control. The skin permeation and the skin primary irritation of the LA decreased and the skin turnover time increased, as the pH increased. The maximum therapeutic index was obtained with pH 3.8, 0.5 M LA. It was suggested that the skin permeability of LA might be a main factor for prediction of the skin irritation and the skin turnover time. On the other hand, the W/O-C containing pH 3.8, 0.5 M LA indicated a good sustained release property of LA, compared with water in oil emulsion without chitosan hydrogel (W/O) or oil in water emulsion (O/W). The skin permeability and the skin irritation of AHAs from the W/O-C edcreased, compared with W/O or O/W, however the skin turnover time showed almost the same value as W/O or O/W. In conclusion, we suggest that the control of the skin permeation of AHAs would be an important tool for reducing the skin irritation and for maintaining the positive effect of AHAs, and the W/O-C system could be a potential candidate for future cosmetological application of AHAs.

• Journal of Fisheries and Marine Sciences Education
• /
• v.25 no.1
• /
• pp.29-39
• /
• 2013

The purpose of this study is to analyze middle school teachers' concern about and implementation degree of performance assessment in China. The research questions are as follows: First, what kind of concern is held by middle school teachers who implement performance assessment? Second, is there any significant difference in stages of concern the teachers on performance assessment according to their gender, education level and teaching career? Third, which level of use is shown by middle school teachers who implement performance assessment? Fourth, what is the correlation between middle school teachers' Stages of Concern and Levels of Use on performance assessment? This study was conducted based on a Concerns-Based Adoption Model (Hall, 1973; CBAM) that viewed teachers as the most primary factor of the execution of innovation, in this case, performance assessment. Performance assessment is assessment based on observation and judgement (Stiggins, 1994), and require test takers to complete a process or produce a product in a context that closely resembles real-life situations. The subjects of this study were randomly sampled from 120 middle school teachers throughout Bei-Jing, China. The questionnaires were distributed to them by mail, and they were asked to return their questionnaire by mail. The collect data were analyzed by SPSS/WIN 18.0 program in terms of frequency, correlation, or MANOVA. Frequency analysis was used to analyze concern of middle school teachers on performance assessment. To gain an frequency of the individuals in each stage, we regarded the stage in which a teacher had his/her highest score as his/her relevant stage. Correlation analysis was adopted to identify the correlation between teachers' stage of concern and level of use. To analyze the difference of the concern of China middle school teachers on performance assessment according to their individual background variables such as gender, education level, and teaching career, MANOVA was performed.

• Journal of Digital Convergence
• /
• v.14 no.6
• /
• pp.199-218
• /
• 2016

The purpose of this study is to investigate the determinants of consumer's repurchase intention in the foreign direct sales shopping malls, focusing on the Japanese customers. Research model of the study is composed of seven independent variables (price competitiveness, product diversity, reputation, country-of-origin image, ease of use, delivery service, after service), a mediating variable (trust) and a dependent variable (repurchase intention). The results of this study show that trust is an important factor affecting the repurchase intention of customers. Customers' trust is affected by the reputation, country-of-origin image, ease of use, delivery service, after service. However, price competitiveness and product diversity, which are hypothesized to affect the trust, are not statistically significant. This study will provide a basis for future research on the foreign direct sales area. In addition, it will provide practical information useful in launching and/or operating the foreign direct sales malls.

• Journal of Digital Convergence
• /
• v.14 no.6
• /
• pp.477-487
• /
• 2016

This study examines the relationship between ego-resilience, mattering and school life adjustments of elementary students participating in physical activity after school. The number of subjects for this study were 429 who were participating in the physical activity after school in Gyeonggi-do. The reliability and validity test of the questionnaire and descriptive analysis, factor analysis, correlation were conducted by using SPSS 20.0 and structural equation model was conducted by using AMOS 20.0 program. The results are as follows; First, ego-resilience of elementary students participating in physical activity after school affects their mattering. Second, mattering of elementary students participating in physical activity after school affects their school life adjustments. Third, ego-resilience of elementary students participating in physical activity after school affects their school life adjustments. Lastly there is a causal relationship between ego-resilience, mattering and school life adjustments of elementary students participating in physical activity after school.