• Special Issue of the Society of Naval Architects of Korea
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• 2013.12a
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• pp.66-72
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• 2013

The demand for an ice class ship is rising expected to rise according to the increase of energy consumption and the opening of arctic sea routes. Ice class ship should be designed to cope with the severe environmental conditions of arctic sea such as a high mechanical impact and abrasion damage, caused by pack ice, ice bergs and low temperature. The ice class ship hulls are coated with an anti-abrasion and low friction coating such as a solvent free epoxy or high solid-volume epoxy. These coatings require two-component heating pump and a high grade surface preparation. In this study, the coating performances for the arctic vessels, such as puncture absorbed energy, abrasive wear loss, friction coefficients and impact absorbed energy were evaluated. Based on this study, a proper coating performance specification for the arctic vessels was proposed and coating selection guideline in terms of coating performance and workability was also established.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.291-294
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• 2012

The research and development status of combustion chamber of liquid rocjet engine for Korea Space Launch Vehicle(KSLV-II) are briefly described. The cold and hot firing tests of uni-element injector, the performance/heat flux measurement/hot firing tests of subscale combustion chamber and the performance/stability rating/regenerative cooling/hot fire tests of 30ton-class combustion chamber were successfully performed. Based on these results, the research and development of combustion chamber for 75ton-class liquid rocket engine are underway.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.3
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• pp.91-108
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• 1998

Automated Storage and Retrieval Systems (AS/RSs) are an important facility for modern material management. The expected benefits of these capital-intensive facilities are gained when their control policies and their physical design parameters are determined simultaneously. In this paper we present several analytical models that capture the impact of the storage assignment policy and of the rack design on the expected storage and retrieval times. Sequential and interleaved service modes are considered for sequencing the storage and retrieval requests. We further investigate the impact of the rack structure on the relative performance of the following storage assignment policies : closest open location (random), full turnover-based policy, and class-based. Our analysis clearly indicates that significant savings in crane travel time are realized when implementing full turnover-based policy, rather than random. These savings become more and more pronounced as the profile of the storage racks approaches the square-in-time shape. Furthermore, it is shown that a class-based policy, with a small number of storage classes, will capture most of these savings and be easier to manage in practice.

• Fashion, Industry and Education
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• v.14 no.1
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• pp.50-58
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• 2016

Passive learning attitudes and lack of enthusiasm in a retailing math course is quite common and a significant number of students do express their frustrations and struggles by seeking extra help outside the classroom. In order to promote students' active participation in class and to improve their performance and overall satisfaction with the course, a modified team-based learning (TBL) method was implemented in a retailing math course in two consecutive semesters. Implementing TBL into a retailing math course would improve students' accountability for their own learning, increase student interactions and engagement, and develop teamwork and collaboration skills. The scores on the midterm and final tests indicated that students' performance improved especially for the students who scored below 80% on each test when TBL was implemented. Students' reflection on the TBL activities done in class throughout the semester indicated that these TBL activities help them solidify the concepts taught in class better. They were able to realize their own mistakes and other group members who got the question right helped them understand. To maximize the benefit of TBL, it is suggested to implement TBL within the flipped classroom. Further research is called for to evaluate the effect of TBL on long-term knowledge retention among college students.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.3
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• pp.81-88
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• 2002

This paper presents a realtime class generation technique for Java performance tuning of enormously repeated codes needing interpreting. Based on interpreted results, a Java source program for a Java class including a method with the corresponding function is generated, compiled, and loaded on the memory. And then and next time, the newly generated method is called for processing the original codes. As the results, overall times of repetition processing is reduced.

• Journal of Engineering Education Research
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• v.21 no.4
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• pp.28-34
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• 2018

Design class through team activities is increasing in engineering education. Team-based education has been known to improve students' creativity, problem solving ability, cooperative ability, self-directed learning ability, and communication ability. How to organize a team is an important issue that affects the performance of team activities as well as student satisfaction. However, previous studies have focused on the causal relationship between team formation and the team's performance. This paper deals with how to organize a balanced team in a real class. When the basic characteristic values of students are givens, the aim is to make the sum of the characteristic values as fair as possible for each team. We propose a mathematical team formation model and show how to apply it through case studies.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.71-78
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• 2023

Purpose : This study was purposed to analyze the effectiveness of PBL (Problem-Based Learning) classes and to derive class improvement plans. Methods : The subjects of the study were 48 students who took the 4th grade clinical dental hygiene course at S University located in Chungcheongnam-do of South Korea in 2021. A single-group pre and post experimental study was designed to verify whether there were significant changes in the research variables of students who participated in the class to which problem-based learning was applied. A paired-sample t-test was conducted for the collected data of 46 respondents. Results : As a result, the degree of improvement in problem clarification, cause analysis, and alternative development among the five sub-areas of problem-solving ability was statistically significant. This means that the problem-based learning class positively affects dental hygiene major students' ability to clarify problems, the ability to analyze causes to collect and analyze information, and the ability to develop alternatives to make decisions, thereby improving overall problem-solving abilities. However, the improved post-score was not statistically significant in the planning/execution and performance evaluation of the remaining two subdomains. In addition, post-scores of the leader aspect, opinion exchange, opinion evaluation, and opinion integration, which are sub-domains of collaborative self-efficacy, all showed great statistical significance. Problem-based learning improved the collaborative efficacy of dental hygiene major students overall by positively influencing the ability to lead a team, exchange and evaluate each other's views, and constructively integrate different views. Conclusion : It was found that both the subject's problem-solving ability and cooperation efficiency improved under the influence of problem-based learning. On the other hand, implications for improvement of the future class such as the necessity of supplementing strategies to promote planning and execution ability for problem solving, and ability to evaluate problem solving performance was suggested.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.12
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• pp.33-39
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• 2015

This paper examines the insulation performance of synthetic air and dry air. This examination was conducted based on dielectric strength in uniform and non-uniform field, electric field distribution by interior structure and defects in gas insulation switchgear (GIS) and insulation performance in different temperatures. From this review, it was found that eco-insulation gas required to possess low moisture content for power equipment in the distribution class. The results of this paper are valuable to ensure the insulation design and insulation reliability of GIS using air.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1876-1878
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• 1999

Developed was a 5kW-class polymer electrolyte membrane fuel cell(PEMFC) system comprised of fuel cell stack, fuel processing, thermal and water management subsystems and ancillary equipments. Several large single cells have been fabricated with different gas flow field patterns and paths, and the gas flow field pattern for the stack has been determined based on the single cell performance of thin film membrane electrode assembly (MEA). The PEMFC stack was consisted of 100 cells with an electrode area of $300cm^2$, having serpentine flow pattern. Fuel processing was developed including an autothermal methanol reformer and two preferential CO oxidation reactors. The fuel processing was combined to PEMFC operation system consisted of air compressor and thermal and water management subsystems. The PEMFC stack showed performance of 5kW under the supply of $H_2$ and air, but its performance was lowered to 3.5kW under the supply of reformed gas.

• International Journal of Computer Science & Network Security
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• v.22 no.10
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• pp.1-10
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• 2022

Nowadays software defect prediction (SDP) is most active research going on in software engineering. Early detection of defects lowers the cost of the software and also improves reliability. Machine learning techniques are widely used to create SDP models based on programming measures. The majority of defect prediction models in the literature have problems with class imbalance and high dimensionality. In this paper, we proposed Centroid and Nearest Neighbor based Class Imbalance Reduction (CNNCIR) technique that considers dataset distribution characteristics to generate symmetry between defective and non-defective records in imbalanced datasets. The proposed approach is compared with SMOTE (Synthetic Minority Oversampling Technique). The high-dimensionality problem is addressed using Ant Colony Optimization (ACO) technique by choosing relevant features. We used nine different classifiers to analyze six open-source software defect datasets from the PROMISE repository and seven performance measures are used to evaluate them. The results of the proposed CNNCIR method with ACO based feature selection reveals that it outperforms SMOTE in the majority of cases.