• Journal of Powder Materials
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• v.30 no.5
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• pp.387-393
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• 2023

Transition metal chalcogenides are promising cathode materials for next-generation battery systems, particularly sodium-ion batteries. Ni₃Co₆S₈-pitch-derived carbon composite microspheres with a yolk-shell structure (Ni₃Co₆S₈@C-YS) were synthesized through a three-step process: spray pyrolysis, pitch coating, and post-heat treatment process. Ni₃Co₆S₈@C-YS exhibited an impressive reversible capacity of 525.2 mA h g^-1 at a current density of 0.5 A g^-1 over 50 cycles when employed as an anode material for sodium-ion batteries. However, Ni₃Co₆S₈ yolk shell nanopowder (Ni₃Co₆S₈-YS) without pitch-derived carbon demonstrated a continuous decrease in capacity during charging and discharging. The superior sodium-ion storage properties of Ni₃Co₆S₈@C-YS were attributed to the pitch-derived carbon, which effectively adjusted the size and distribution of nanocrystals. The carbon-coated yolk-shell microspheres proposed here hold potential for various metal chalcogenide compounds and can be applied to various fields, including the energy storage field.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.23-32
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• 2017

The joints between precast PSC slabs of the intermediate road slab in double deck tunnel are inevitably generated in the road traffic vehicle traveling direction. Therefore, it is important to make the behavior of parts on the joint in one piece. The imtermediate road slab system of double deck tunnel in great depth proposed in this study will be constructed with precast PSC slab in order to minimize the construction period. And the joint connection between the precast slab has been developed in two methods: the 'Transverse tendon reinforcement method' and 'High strength bolts connection method'. Also, the experiments were performed for the full scale model in order to evaluate the performance of the intermediate road deck slab with two type joints systems, the structural stability was verified through the F.E.M analsysis. The results of static loading test and F.E.M analysis investigated a very stable behavior of intermediate road deck slab in double deck tunnel applying the joint methods developed in this study, in the cracks and deflections to satisfy the design standards of Highway Roads Bridges (2011), it was determined that there is no problem even servicebility.

• Korea Journal of Hospital Management
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• v.6 no.1
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• pp.120-146
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• 2001

This study was carried out to provide the essential information in improving the graduate medical education in Korea. For the study, a survey targeting the directors of GME of nationwide teaching hospitals was performed with a questionnaire asking the questions such as the director's perception on the quality of GME, trainees' salary level, trainees' specialty selection tendency, training system and its duration. The collected data were analyzed using t-test, ANOVA, and $x^2$-test. The results were as follows: 1. The survey were executed on 240 teaching hospitals in Korea and the response rate was 66.2% (159 hospitals replied). 2. The bigger a hospitals is the better in Quality of education. Larger hospitals tend to have better status in all items including medical specialists' experience, contents of medical curriculum, general environment for medical education and medical trainees's salary level. The result supported the general perception on the positive relationship between hospital size and Quality of GMA. 3. Providing convenience for medical trainees who prepares for the medical specialist Qualifying examination didn't affect the results of the examination. 4. The directions of GME have a perception that the trainees give positive impact on financial performance of their hospitals. This seems to be one of the reasons that hospitals try to retain as many trainees as possible. 5. The directors of GME considered medical trainees as an educate, and most of them responded positively on the need of governmental supports for the education cost and the trainee's salary. Considering above results, it seems that GME would get more social attention and the trainees' impact on hospitals operation would be increased more than before. In response to these trends, hospitals would find out the ways to lower dependency on trainees, and this change of attitude of hospitals on the GME would cause problems in operation of hospitals and GME itself. In order to prevent these problems the policy on GME should be directed in following ways. 1. The contents of Qualifying examination for specialist should be improved. 2. The curriculum of GME should be strictly followed. 3. The status of trainee in a hospital has to be defined as eductee. 4. Government has to support a half of the education cost and salary of trainee. 5. The distribution of the trainee among the hospital group have to be based on total available. 6. The financial support and welfare of trainee should be improved gradually and systematically.

• Spatial Information Research
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• v.1 no.1
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• pp.39-53
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• 1993

A geographical information systems(GIS) was a useful aid in the assessment of urban nonpoint source pollution and the development of a pollution control strategy. The GIS was used for data integration and display, and to provide data for a nonpoint source model. An empirical nonpoint source loading model driven by land use was used to estimate pollutant loadings of priority pollutant. Pollutant loadings were estimated at fine spatial resolution and aggregated to storm sewer drainage basins(sewershedsl. Eleven sewersheds were generated from digital versions of sewer maps. The pollutant loadings of individual land use polygons, derived as the unit of analysis from street blocks, were aggregated to get total pollutant loading within each sewershed. Based on the model output, a critical sewershed was located. Pollutant loadings at major sewer junctions within the critical sewershed were estimated to develop a mi t igat ion strategy. Two approaches based on the installat ion of wet ponds were investigated -- a regional approach using one large wet pond at the major sewer outfall and a multi-site approach using a number of smaller sites for each major sewer junction. Cost analysis showed that the regional approach would be more cost effective, though it would provide less pollution control.