• Journal of Information Technology Services
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• v.20 no.6
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• pp.17-43
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• 2021

Currently, various discussions are underway to establish a more advanced management system for public rental housing. Also, it calls for improvement methods for problems arising in management of the current rental housing system. In this regard, this study aims to evaluate determinants that affect user acceptance intention of blockchain technology to implement a new system that complements drawbacks of the current public rental housing system. The study uses the Unified Theory of Acceptance and Use of Technology (UTAUT) as a theoretical model; the study model utilizes three UTAUT variables -performance expectancy, social influence, and Facilitating conditions-, applies security, availability, and reliability that are perceived from blockchain technology as external parameters to facilitate understanding of user acceptance intention of blockchain technology, and evaluates whether innovativeness can regulate the influence of performance expectancy, social influence, and Facilitating conditions on user acceptance intention of blockchain technology. Based on the significant survey result where 274 IT technicians participated, the study applies structural equation modeling to explore structure of user acceptance intention in the blockchain-based management system for public rental housing. As a result, security-reliability and availability are found to factors as determinants for user acceptance intention, affecting implementation of the public rental housing management system, while innovativeness shows no significant statistical results related to regulation effect. This study has implications in that it understands characteristics of blockchain and empirically analyzes the relationship between the characteristics and acceptance intention to enable blockchain's contribution to activate the public rental housing management system in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.345-356
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• 2012

Road pavement requires repetitive maintenance works to maintain satisfactory service level to the public. However, the repetitive maintenance works upon deteriorated pavement structure make negative effects to deterioration speed. It often leads to inefficient use of limited budget. For that reason, the pavements require reconstruction work to recover their original performance. Recently, construction demands in the Korean national highway have already been reached to maximum level, and the aged pavements start to demand much more reconstruction works. However, in the real world, road agencies have often been confused when they determine maintenance design for such aged road sections due to budget constraint. It is because there is no reliable long-term maintenance strategy that supports their decision making. To support their decision making, this paper aimed to suggest the best maintenance strategy considering changing process of pavement performance by repetitive maintenance works. As an analysis method, probability distribution and hazard function to estimate the life expectancy were adopted, and then the results were used for long-term life cycle cost analysis with deterministic or Monte-Carlo method under various scenarios. As an empirical study, the Korean national highway data that has long-maintenance history data since 1986 has been applied. Last, this paper considered quality assurance of maintenance work to improve maintenance quality. These could be important information as a part of long-term maintenance strategy of pavement.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.162-169
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• 2000

A Direct Drive Valve(DDV) hydraulic actuation system which is commonly used as an aircraft's control surface driving actuator has multi-loop control structure to ensure its safety operation. However, because of not perfect matching of one self channel characteristics with the others, the servo valve driving current of each channel can be widely different. Therefore, the long-time use of DDV actuator without any correction of these channel current offsets will cause the problem of performance or life expectancy degradation due to unwanted heats in the linear motor. A current equalization loop structure which can minimizes current offsets between channels is introduced and designed. The performance of the current equalization loop is investigated and verified through the analytic and experimental ways.

• Transactions of Materials Processing
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• v.21 no.2
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• pp.131-137
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• 2012

With the advantages of power savings, increased life expectancy and fast response time over traditional incandescent bulb, LEDs are increasingly used for many applications including automotive, aviation, display, and special lighting applications. Since the high heat generation of LED chips can reduce service life, degrade luminous efficiency, and cause variation of color temperature, many studies have been carried out on the optimization of LED packaging and heat sinks. In this study, a fin expansion type cooling device using heat pipe, instead of a solid aluminum heat sink, was designed for LED security lightings based on thermal resistance analysis. Numerical analysis and experimental validation were carried out to evaluate its cooling performance.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.391-399
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• 2006

In order to solve the optimization problem of designing the trajectory of three-dimensional horizontal well, we establish a multi-phase, nonlinear, stochastic dynamic system of the trajectory of horizontal well. We take the precision of hitting target and the total length of the trajectory as the performance index. By the integration of the state equation, this model can be transformed into a nonlinear stochastic programming. We discuss here the necessary conditions under which a local solution exists and depends in a continuous way on the parameter (perturbation). According to the properties we propose a revised Hooke-Jeeves algorithm and work out corresponding software to calculate the local solution of the nonlinear stochastic programming and the expectancy of the performance index. The numerical results illustrate the validity of the proposed model and algorithm.

• Journal of Digital Convergence
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• v.15 no.5
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• pp.27-36
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• 2017

SNS has been emerged as an effective educational tool in college and many studies on various teaching models and methodologies have been made in order to utilize SNS in education. The purpose of this paper is to empirically investigate the effect of affecting factors of SNS on learner's attitude, intention to re-use and performance in converging college educational environment. Self-efficacy on media usage, educational expectancy, subjective norm, habit, and enjoyment were identified as affecting factors based on prior researches. An empirical analysis was attempted by survey targeting college students. The results of structural equation model using Smart PLS shows that educational expectancy, subjective norm, and enjoyment are significantly related to the learner's attitude on use of SNS in college education, but Self-efficacy on media usage and habit are not. Learner's attitude on SNS in college education was found to be significantly related to the intention to continuous use and performance. This study implicates that using SNS in university class makes learner's attitude positively and finally lead to good performance. The analysis results can provide a guideline of effective strategy for SNS utilization in college education.

• Informatization Policy
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• v.25 no.2
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• pp.46-66
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• 2018

This research explores the factors affecting infusion of public administrative information systems(IS) and analyzes its impact on work performance. For this purpose, the factors affecting the infusion of IS are classified into voluntary and involuntary motivations based on the self-determination theory that explains individual motivations. As factors for voluntary motivation, performance expectancy, personal innovativeness, and organizational citizenship behavior are proposed, while government influence, competitor influence, and the top-level management influence are proposed as factors for involuntary motivation. The analysis shows the voluntary motivation factors-performance expectancy, personal innovativeness, and organizational citizenship behavior-do affect infusion of IS, whereas the involuntary motivation factors-government influence, competitor influence, and the top-level management influence-have no statistically significant impact on the infusion of IS. The relationship between infusion of IS and work performance is found significant. While individuals are unable to decide on the adoption of IS in an involuntary environment such as in the case of using the public administrative IS, the results show that the factors related to individual autonomy have an important role in extended, active usage of IS beyond the mandatory level.

• Fire Science and Engineering
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• v.24 no.6
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• pp.89-97
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• 2010

In recent fire protection system, the pipings should be light weighted, seismic proof and wrought with non-welding method. The light weighted stainless steel pipes and fittings, satisfying these requirements, are already used as a fire protection system in Germany, Netherland, Taiwan, Australia, United States and Japan. Accordingly, performance evaluation tests were carried out to determine whether or not the fittings can be used in the pipings. As the performance evaluation tests, we conducted vibration test, water hammering test, bending test and fire test. With the results of the tests, we concluded that the fittings can be used in the fire protection system, and that the life expectancy of the fittings exceeds that of buildings.

• Journal of The Korean Association For Science Education
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• v.17 no.4
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• pp.415-423
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• 1997

The purposes of this study were to investigate the intercorrelations among various motivational patterns and learning strategies and to examine the differences in motivation and strategy usage in terms of students' science achievement level, gender, and grade. A questionnaire on achievement goal, self-efficacy, self-concept of ability, expectancy, value, causal attributions, and learning strategies was administered to 360 junior high/high school students (178 males, 182 females). Students who adopted performance-oriented goal tended not to be task oriented. Task-oriented students had high levels of self-efficacy, high self-concept of ability, and expectancies for future performance in science. They also valued science and attributed thier failures to the lack of effort. However, performance-oriented students evaluated their ability negatively, did not value science, and attributed thier failures to uncontrollable causes. With respect to learning strategy, task-oriented students tended to use deep-level strategy, whereas performance-oriented students tended to use surface-level strategy and not to use deep-level strategy. High-achieving students, boys, and junior high school students were more task-oriented, evaluated their ability more positively, and valued science more than low-achieving students, girls, and high school students, respectively. High-achieving students and boys also used deep-level strategy more than each of their counterparts. However, no significant difference in learning strategy was found between junior high school students and high school students. Educational implications of these findings are discussed.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.7
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• pp.778-784
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• 2012

In comparison with some other light sources, LED has merits such as increased life expectancy, fast response, pollution free, and high energy efficiency. Lately, due to development of LED with high brightness and capacity, LED has widely used in many industrial fields such as automotive, aviation, display, transportation and special lighting applications. Since the high heat generation of LED chips can cause a reduction in lifetime, degradation of luminous efficiency, and variation of color temperature, studies have been carried out on the optimization of LED packaging and heat sinks. In this study, experiments on measuring the heat generation rate of LED and the cooling performance of a heat sink were carried for analyzing the thermal characteristics of LED lighting system in free convection. From the results, dimensionless correlation on the cooling performance of heat sink in natural convection was proposed with Nusselt number and Rayleigh number as a guideline for designing cooling device of LED lightings.