• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.719-724
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• 2016

This paper describes the performance improvement of an inrush current limiter to prevent damage or malfunctions in power converters due to the inrush current. When the power converter of military radar is operated, the circuit breaker of the power converter is often activated because the overcurrent flows through the circuit breaker of the power converter. Therefore, this study performed a cause analysis of the problem, which is a larger current flow than the intended current(250A). The operation principle of an inrush current limiter and SCR (Silicon Controlled Rectifier) used in the inrush current limiter was analyzed. As a result, the overcurrent flow through the circuit breaker was found to be due to dv/dt triggering of SCR. Based on cause analysis, this paper proposes a technique by adding the resistor in front of the SCR to prevent an unnecessary inrush current. Finally, the effectiveness of the improvement was verified by measuring the output current in the inrush current limiter. The power converter equipped with the improved inrush current limiter operated for more than 1 year without the circuit breaker of the power converter being activated.

• Korean Journal of Remote Sensing
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• v.21 no.4
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• pp.341-369
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• 2005

Hyperspectral images have emerged as a new and promising remote sensing data that can overcome the limitations of existing optical image data. This study was designed to provide a comprehensive review on definition, data processing methods, and applications of hyperspectral data. Various types of airborne, spaceborne, and field hyperspectral image sensors were surveyed from the available literatures and internet search. To understand the current status of hyperspectral remote sensing technology and research development, we collected several hundreds research papers from international journals (IEEE Transactions on Geoscience and Remote Sensing, International Journal of Remote Sensing, Remote Sensing of Environment and AVIRIS Workshop Proceedings), and categorized them by sensor types, data processing techniques, and applications. Although several hyperspectral sensors have been developing, AVIRIS has been a primary data source that the most hyperspectral remote sensing researches were relied on. Since hyperspectral data have very large data volume with many spectral bands, several data processing techniques that are particularly oriented to hyperspectral data have been developed. Although atmospheric correction, spectral mixture analysis, and spectral feature extraction are among those processing techniques, they are still in experimental stage and need further refinement until the fully operational adaptation. Geology and mineral exploration were major application in early stage of hyperspectral sensing because of the distinct spectral features of rock and minerals that could be easily observed with hyperspectral data. The applications of hyperspectral sensing have been expanding to vegetation, water resources, and military areas where the multispectral sensing was not very effective to extract necessary information.

• Korean Journal of Remote Sensing
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• v.24 no.2
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• pp.99-106
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• 2008

A synthetic aperture radar (SAR) system is of great interest in many fields of civil and military applications because of all-weather and luminance free imaging capability. SAR image quality parameters such as spatial resolution, peak to sidelobe ratio (PSLR), and integrated sidelobe ratio (ISLR) can be normally estimated by modeling of impulse response function (IRF) which is obtained from various system design parameters such as altitude, operational frequency, PRF, etc. In modeling of IRF, however, background clutter environment surrounding the IRF is generally neglected. In this paper, analysis method for SAR mage quality is proposed in the real background clutter environment. First of all, SAR raw data of a point scatterer is generated based on various system parameters. Secondly, the generated raw data can be focused to ideal IRF by range Doppler algorithm (RDA). Finally, background clutter obtained from image of currently operating SAR system is applied to IRF. In addition, image quality is precisely analyzed by zooming and interpolation method for effective extraction of IRF, and then the effect of proposed methodology is presented with several simulation results under the assumption of estimation error of Doppler rate.

• Korean Journal of Comparative Education
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• v.27 no.4
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• pp.155-186
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• 2017

The purpose of the study is to analyze the operational case of gap year which can explore about guidance in some times before college entrance or during college life in the universities of main nations(England, American, and Japan) and draw from some implications for possibility of it's introduction in Korean university. It means that before students enter the college after finishing high school, they have various guidance activity and voluntary service activity for experiencing self-understanding out of regular curriculum. The study analyzed four universities in America, two universities in England, and one university in Japan. The main results indicate that the gap year can divide into system and university assisting finance. Based on the results and their implications of gap year case analysis in universities of England, America, and Japan, the study suggests that it needs to consolidate the related system of university and assist some finances, and systematic steps such as career exploration, career decision-making, career plan, and career preparation should be constructed.

• Korean Journal of Social Welfare Studies
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• v.48 no.1
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• pp.113-141
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• 2017

Child welfare centers not only protect children at the first line of community, but also perform the tasks of systematic social service by linking the various resources of community and establishing a support system for children. Making quantitative growth, child welfare centers are faced with a request for operational systemicity and professionalism in terms of quality. This study set out to investigate the effects of professional capability, psychological capital, and career-related continuous learning on the job performance among practitioners of child welfare centers. For those purposes, the study conducted a survey by mail with those who were working for child welfare centers in Busan and Gyeongnam Province from March 2 to 25, 2016. Of the collected questionnaires, 550 whose responses were sincere were used in the final analysis. The analysis results show that psychological capital had the biggest influence on the job performance among practitioners of child welfare centers. Furthermore, in the chief of child welfare centers, the more having of professional capability, the more job performance they experienced. However, in the front-line social workers, professional capability did not affect the job performance. Those results indicate that the expansion of psychological capital should be a top priority to help the practitioners of child welfare centers improve their job performance. Based on those findings, the study offered some implications for the organizational management of child welfare centers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.459-467
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• 2019

The landing gear is a component that requires a high degree of safety to protect the lives of rotary-wing aircraft and boarding personnel, absorbing the impact on transfer/landing and supporting the fuselage during taxiing and mooring on the ground. In particular, the wheel landing gear supporting the aircraft fuselage absorbs most of the shock from the ground through the shock absorber and tires. This ensures the safety of the pilot on board the aircraft and satisfies the operational capability of the soldiers between missions. During the operation of a rotary-wing aircraft, a number of piston pins, which are a component of the right main wheel landing gear, were found to be broken. Therefore, this study examined the root cause of the piston pin crack phenomenon found in the main wheel landing gear. For this purpose, various causes were identified from fracture surface analysis of a flight test. In particular, the possibility of cracking was analyzed based on the influence on the fastening torque with the drag beam component applied to the piston pin at the time of development. This ensures the fatigue life and structural integrity.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.175-186
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• 2021

The roles and functions of domestic public libraries are diversifying, but various problems have emerged due to internally biased book lending. In addition, due to the 4th Industrial Revolution, public libraries have introduced a book recommendation system focusing on popular books, but the variety of books that users can access is limited. Therefore, in this study, the public library unborrowed book recommendation system was implemented limiting its spatial scope to Duryu Library in Daegu City to enhance the satisfaction of public library users, by using the loan records data (213,093 cases), user information (35,561 people), etc. and utilizing methods like cluster analysis, topic modeling, content-based filtering recommendation algorithm, and conducted a survey on actual users' satisfaction to present the possibility and implications of the unborrowed book recommendation system. As a result of the analysis, the majority of users responded with high satisfaction, and was able to find the satisfaction was relatively high in the class classified by specific gender, age, occupation, and usual reading. Through the results of this study, it is expected that some problems such as biased book lending and reduced operational efficiency of public libraries can be improved, and limitations of the study was also presented.

• 재활복지
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• v.18 no.4
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• pp.165-186
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• 2014

The purpose of the study is intended to analysis on students adjustment of students with disabilities in a special class of the elementary school focused on KCI journals through a systematic review. This study was searched from papers published from Jan, 2004 to May, 2014 using KISS, DBPIA, RISS, Google databases. The key words were "inclusive education, special class, inclusive class, student with disabilities, school adjustment, school life, school adjustment scale, elementary school". Results of data analysis were follows; 1. A total of 35 papers were analyzed. Except for 6 papers published in 2004~2007, 29 papers were published after 2008.; 2. The participant of study subject was total 141. Students with intellectual disability were 61.7%. Students with learning disabilities were 17.0%.; 3. The assessment domain of study was analyzed total 51 data.; academic achievement and task performance (25.4%), class attitude and participatory behavior(23.5%), problem behavior(21.5%). The Study in student with intellectual disability was 10 assessment domains.; 4. The method of assessment was total 41.; the use of operational definition(56.1%), the development of test (17.1%), and the use of assessment tool(14.6%).

• Journal of Korea Technology Innovation Society
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• v.22 no.2
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• pp.159-185
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• 2019

Chemical industry, as one of the basis industries of the country, is characterized by converged high-end technology and large scale capital investment. In 2018, the government announced "The Strategy for Chemical Industry Development" with the vision of 'An Upgrade to the Advanced Chemical Industry'. In the meantime, the advanced chemical industry in Korea has been developed not by its own R&D, but by the upgrading of technologies and processes through the technology transfer from developed countries. The method of technology transfer was mainly achieved with international joint ventures (hereafter IJV) linked with technology transferors from developed countries. As it is necessary to grasp the determinants of the technology transfer and their importance to promote the transfers through IJVs, this relative importance analysis study was conducted by using the method of quantifying experts' opinions (AHP) on the determinants of the technology transfer of both parties. As a result of the analysis, in the Hierarchy1(PEST factors), the technology transferees focus on economic factors such as 'profitability of technology transfer' and 'cost efficiency', while technology transferors considered technical factors such as 'operational excellence (abilities to continuously improve technology process)'. In addition, transferors and transferees have different priorities for technology transfer determinants in all areas of Hierarchy 2 (sub-determinants). This suggests that Korean government or enterprise should shift the policy direction toward 'technology-oriented' when they promote advanced-technology transfer through IJVs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.1-7
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• 2019

As a unify operational processes of the safety inspection for major national facilities, it is expected that the efficiency and professionalism of the project will be enhanced. Also it is being emphasized that the importance of visual inspection that initially find physical and functional defects in facilities. In this study, we developed an E-PAD-based condition evaluation system to check the safety of the facility to overcome the problems and limitations of the existing inspection method. This system consists of introduction, work list, visual inspection, defect table and so on. It is possible to download the inspection drawings at the site and input the damage information to the drawings and check the evaluation grade. In order to verify the E-PAD based condition evaluation system, the inspection data of 10 sample bridges were inputted into the system and the evaluation results were compared. As a result, it was confirmed that the safety grade calculated from the system and the existing safety grade are the same. The feasibility analysis of the AHP method also showed that the function increased by 10%, cost by 36%, and value by 30% compared to the existing method. Therefore, it is expected to contribute to systematic data and information analysis system for improvement of facility management.