• Progress in Superconductivity
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• v.10 no.1
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• pp.60-67
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• 2008

We present domestic efforts for superconducting fault current limiter (SFCL) application in the Korea Electric Power Corporation (KEPCO) grid and pending points at issue. KEPCO's decision to upgrade the 154 kV/22.9 kV main transformer from 60 MVA to 100 MVA cast a problem of high fault current in the 22.9 kV distribution lines. The grid planners supported adopting an SFCL to control the fault current. This environment friendly to SFCL application must be highly dependent upon the successful development of SFCL having specifications that domestic utility required. The required conditions are (1) small size of not greater than twice of 22.9 kV gas insulated switch-gear (GIS), (2) sustainability of current limitation without the line breaking by circuit breakers (CB) for maximum 1.5 seconds. Also, optionally, recommended is (3) the reclosing capability. Conventional resistive SFCLs do not meet (1) $\sim$ (3) all together. A hybrid SFCL is an excellent solution to meet the conditions. The hybrid SFCL consists of HTS SFCL components for fault detection and line commutation, a fast switch (FS) to break the primary path, and a limiter. This characteristic structure not only enables excellent current limiting performances and the reclosing capability, but also allows drastic reduction of HTS volume and small size of the cryostat, resulting in economic feasibility and compactness of the equipment. External current limiter also enables long term limitation since it is far less sensitive to heat generation than HTS. Semi-active operation is another advantage of the hybrid structure. We will discuss more pending points at issues such as maintenance-free long term operation, small size to accommodate the in-house substation, passive and active control, back-up plans, diagnosis, and so on.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.9
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• pp.747-755
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• 2014

The heat transfer mechanism for radiation is directly related to the emission of photons and electromagnetic waves. Depending on the participation of the medium, the radiation can be classified into two forms: surface and gas radiation. In the present study, unknown radiation properties were estimated using an inverse boundary analysis of surface radiation in an axisymmetric cylindrical enclosure. For efficiency, a repulsive particle swarm optimization (RPSO) algorithm, which is a relatively recent heuristic search method, was used as inverse solver. By comparing the convergence rates and accuracies with the results of a genetic algorithm (GA), the performances of the proposed RPSO algorithm as an inverse solver was verified when applied to the inverse analysis of the surface radiation problem.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.187-192
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• 2017

This paper presents an ongoing study to develop a novel pressure sensor by means of a Nano Carbon Piezoresistive Composite (NCPC). The sensor was fabricated using the 3D printing process. We designed a miniaturized cantilever-type sensor electrode to improve the pressure sensing performance and utilized a 3D printer to build a small-sized body. The sensor electrode was made of 2 wt％ MWCNT/epoxy piezoresistive nano-composite, and the sensor body was encapsulated with a pipe plug cap for easy installation to any pressure system. The piezoresistivity responses of the sensor were converted into stable voltage outputs by using a signal processing system, which is similar to a conventional foil strain gauge. We evaluated the pressure-sensing performances using a pressure calibrator in the lab environment. The 3D-printed cantilever electrode pressure sensor showed linear voltage outputs of up to 16,500 KPa, which is a 200％ improvement in the pressure sensing range when compared with the bulk-type electrode used in our previous work.

• The Korean Journal of Health Service Management
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• v.1 no.1
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• pp.125-137
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• 2007

The current hospital industry is showing relatively low profitability in comparison with other industries due to the low medical fees and high costs. Therefore, our government presented the direction of improvement through model execution and support of the specialized hospitals. However, it is estimated that the specialized hospitals also will show differentiated management performances in accordance with their specialized fields due to the characteristics of medical treatment. Therefore, this study had attempted an analysis on the financial index in accordance with the weight of medical treatment items for the rehabilitative medicine department among the whole hospital groups through getting out of analyzing financial indices of individual hospitals centered at their costs. For this p개pose, this study had carried out its research by partially reciting the study on the plan for utilizing participations of private health resources to expand rehabilitative medicine services into the private people of the Korea Health Industry Development Institute(KHIDI). As its results, it was shown that the stability, profitability, activity and productivity of hospitals with high weight of medical treatment for the rehabilitative medicine department were lower than those for the general hospitals. To support smooth operations of these hospitals 'with high weight of medical treatment for the rehabilitative medicine department or of specialized rehabilitation hospitals, it is judged that the plan such as the support for hospital management fund and the additional recognition on the rehabilitative fees, etc. together with the actualization of medical fees must be provided for the institutions which are providing rehabilitative medical services more than the fixed percentage and being equipped with the sufficient medical equipment and personnel to do them.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.4
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• pp.172-179
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• 1988

A cartridge type hydraulic logic valve consists of simple two port valve whose poppet is closed or opened by means of pressure signal of a pilot line. Accordingly, the logic valve can be used not only for direction, flow and pressure control purpose but also for versatile function valve which enables all above mentioned functions. In addition, the valve has little internal leakage and pressure loss, superior response characteristics and easiness in making small block type valve. The above mentioned good performances being recognized recently, the logic valve has been used widely in the large scale hydraulic system such as a hydraulic press system, for the performance requirements of high speed operation and precise control characteristics. However, there are scarce reports until now, except for a few ones from Aachen Institute of Technology in West Germany, so it is necessary to be studied on development and investigation for practical application. This paper showed that the static and dynamic characteristics of a logic valve when the logic valve is used for directional control, to investigate the relations between the valve operating characteristics and the valve design conditions. From the above mentioned procedure, it was ascertained that the valve operation characteristics obtained by numerical analysis showed good agreements with experimental results. The representative results obtained are as follows; 1. During the valve is closing, the poppet velocity is almost constant in the logic valve. 2. The pilot pressure P sub(3) and the resistance R in the pilot line have much influences on the valve operation time. 3. Spring strength have not such a severe influence on the valve operating time. 4. The operation characteristics of the logic valve can be estimated with good accuracy comparatively by numerical analysis with the equations describing poppet motion.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.139-145
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• 2006

This paper develops pedestrian fatality models capable of producing the probability of pedestrian fatality in collision between vehicles and pedestrians. Probabilistic neural network (PNN) and binary logistic regression (BLR) ave employed in modeling pedestrian fatality pedestrian age, vehicle type, and collision speed obtained from reconstructing collected accidents are used as independent variables in fatality models. One of the nice features of this study is that an iterative sampling technique is used to construct various training and test datasets for the purpose of better performance comparison Statistical comparison considering the variation of model Performances is conducted. The results show that the PNN-based fatality model outperforms the BLR-based model. The models developed in this study that allow us to predict the pedestrian fatality would be useful tools for supporting the derivation of various safety Policies and technologies to enhance Pedestrian safety.

• Journal of Technology Innovation
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• v.22 no.3
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• pp.261-286
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• 2014

Recently, project performance and management of government R&D program investing huge amount of budget is being focused. In this study, I built a model for estimating the performance creating paths of the government R&D program, then I analyzed the attributes of performances created by industries. I used simultaneous equations with FIML and examined the IT industry and CT industry of industrial technology innovation program using survey on R&D performance conducted by KEIT. On the analysis result, all the companies create the innovation performance through the government grants. However, the one who commercialize patents is SMEs in IT industry, and conglomerates in CT industry. SMEs in IT industry, which has characteristic of complex product, need extra self innovation activities even the government supports them. For improving the commercialization performance and technology development of SMEs in CT industry, it is effective when conducting cooperative research. These findings give us the implication that it is needed to consider different factors by industrial and enterprise characteristic when planning the public policy and government tasks.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.544-544
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• 2014

Energy harvesting technology, which scavenges electric power from ambient, otherwise wasted, energy sources, has been explored to develop self-powered wireless sensors and possibly eliminate the battery replacement cost for wireless sensors. Among ambient energy sources, vibration energy can be converted into electric power through a piezoelectric energy harvester. For the last decade, although tremendous advances have been made in design methodology to maximize harvestable electric power under a given vibration condition, the research in reliability assessment to ensure durability has been stagnant due to the complicated nature of the multiple failure modes of a piezoelectric energy harvester, such as the interfacial delamination, fatigue failure, and dynamic fracture. Therefore, this study presents the first-ever system reliability analysis for multiple failure modes of a piezoelectric energy harvester using the Generalized Complementary Intersection Method (GCIM), while accounts for the energy conversion performance. The GCIM enables to decompose the probabilities of high-order joint failure events into probabilities of complementary intersection events. The electromechanically-coupled analytical model is implemented based on the Kirchhoff plate theory to analyze its output performances of a piezoelectric energy harvester. Since a durable as well as efficient design of a piezoelectric energy harvester is significantly important in sustainably utilizing self-powered electronics, we believe that technical development on system reliability analysis will have an immediate and major impact on piezoelectric energy harvesting technology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5095-5108
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• 2014

The aim of this study was to compare the perceptions of the role performance of a clinical research coordinator (CRC) between the investigators and clinical research associates (CRAs). Data was collected using a structured questionnaire from 39 investigators and 68 CRAs in 4 hospitals from March 7 to November 30, 2011 and analyzed using descriptive statistics and a t-test. The investigators and CRAs were aware of the importance of CRC's role and they all gave the highest values for patients care management. On the other hand, the score of the role performance items showed perceptional differences between investigators and CRAs. Therefore, the development of detailed job descriptions and manuals will be needed to reduce the perceptional differences in the role performance of the CRC.

• Journal of Korean Academic Society of Home Health Care Nursing
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• v.7 no.1
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• pp.73-82
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• 2000

Twenty-first century coming of health care in our country is in a situation of much conflict because the relationship between nurses and doctors is seen in terms of a traditional and vertical structure. Accordingly. it is very difficult to find collaboration amongst individuals of these two professions. Now nursing is trying to find independence and autonomy by carrying out independent professional skills. This study on collaboration and the obstacles hindering its pursuit. The strategies of collaboration to give better health care quality are as follows; First, a program for professionals should be developed to enhance professional knowledge and technology and train nursing professionals so that nursing can be acknowledged as a profession with a power to carry out on independent job. Second, collaboration reduces expenses and results in satisfactory performances of duty, high productivity, low incidence of medical accident, and higher satisfaction of the patient. Therefore the leader in the higher position should take positive stance for collaboration and help create a cooperative situation through the development of practical orders for collaboration. opening cooperative wards, and meeting for collaboration. Third, a collaboration model should be introduced into the courses of the nursing and medical school curriculum, which would influence job atmosphere after graduation. Fourth, nurses should have pride in their jobs as professionals and have confidence in their professional skill, knowledge and ability. Nurses should make an effort to share responsibility and have independence and autonomy. Fifth, common people as well as doctors know little about professional practice and the role of nurses, so a publicity campaign is also required.