• 한국건설순환자원학회논문집
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• 제5권2호
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• pp.168-176
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• 2017

본 연구에서는 원전 구조물용 콘크리트의 잔골재로 부순모래를 사용하기 위한 연구의 일환으로 기존의 부순모래 생산공정에서 임팩트크러셔(Impact crusher)의 성능(회전수)을 높여 입형을 개선하고 ASTM C 33에 적합하도록 입도를 조정한 부순모래의 입형 및 입도 특성을 검토하였으며, 강모래에 대한 치환률에 따라 콘크리트를 제조하여 콘크리트 배합 특성, 굳지 않은 콘크리트 특성 및 경화한 콘크리트 특성을 검토하였다. 실험결과, 대부분의 콘크리트 특성이 강모래만을 사용한 콘크리트와 동등한 수준으로 나타났지만, 강모래에 대한 치환률 50% 이상일 경우, 치환률 증가에 따라 허용 범위 내에서 공기량, 압축강도 및 인장강도는 다소 감소되는 것으로 나타났다.

• 한국군사과학기술학회지
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• 제18권6호
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• pp.743-754
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• 2015

FASCAM is a newly introduced mean against enemy fire power and supposed to be scattered on base areas in front of a tunnel so as to deter maneuver and shooting of enemy artilleries. However, for its characteristics different from conventional munitions, only a few studies have been undertaken on operations system using this new measure. In this research, we propose a procedure to describe and analyze mathematically an operation system for suppression of enemy fire power using FASCAM. Two suggested simulation methods, impact point generation and density integration, both can describe the actual operation rationally and each has advantages of its own respectively. Further, we demonstrated an example analysis to derive an optimal suppression plan based on the proposed procedure.

• 대한전자공학회논문지
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• 제27권7호
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• pp.1033-1041
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• 1990

In this paper, under pinch-off conditions, the gate-drain breakdown voltage characteristics of GaAs Power MESFET's as a function of device parameters such as channel thickness, doping concentration, gate length etc. are analyzed. Using the Green's function, the gate ionic charge induced by the depleted channel ionic charge is calculated. The impact ionization integral by avalanche multiplication between gate and drain is used to investigate breakdown phenomena. Especially, the localized excess surface charge effect as well as the uniform surface charge effect on breakdown voltage is considered.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.81-84
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• 2001

In the power system of a satellite, solar array and a battery have directly impact on the life time of the satellite, and their stable operation is decided by whether their states are in the steady state operation or not. In this study, solar array capacity and battery characteristics of proposed communication satellite are designed and simulation is conducted according to the operation mode. Each operation mode is classified as the normal and worst case modes, respectively. The normal mode is analyzed under daylight and the eclipse with the EHT burn, and the worst case modes which have solar cell circuit failure, and battery cell failure are analyzed too.

• 한국초전도ㆍ저온공학회논문지
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• 제10권1호
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• pp.62-66
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• 2008

The characteristic of the superconducting magnetic energy storage(SMES) system is faster response, longer life time, more economical, and environment friendly than other uninterruptible power supply(UPS) using battery. So, the SMES system can be used to develop methods for improving power quality where a short interruption of power could lead to a long and costly shutdown. Recently, cryogen free SMES has developed using BSCCO(Bismuth Strontium Calcium Copper Oxide) wire. We fabricated and tested the conduction cooling system for the 600 kJ class HTS SMES. The experiment was accomplished for the simulation coils. The simulation coils were made of aluminium, it is equivalent to thermal mass of 600 kJ HTS SMES coil. The coil is cooled with two GM coolers through the copper conduction bar. In this paper, we report that the test results of cool-down and heat loads characteristics of the simulation coils. The developed conduction cooling system adapted to 600 kJ HTS SMES system and cope with the unexpected sudden heat impact, too.

• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.435-441
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• 2010

To verify the possibility of a power generation system using biogas from the waste of pig farm for rural electric production, a SI gasoline engine is modified to use biogas fuel and was installed in a 20 KVA power generation system. An electronic speed regulation unit is developed to keep the system speed at 1500 rpm. Experimental investigations have been carried out to examine the performance characteristics of power generation system (such as: system frequency, phase output voltage,$\ldots$). In addition, the operating parameters and output emissions ($NO_x$, HC, and $CO_2$) of biogas-fueled engine are preliminary evaluated and analyzed for the change of system load. Results indicated that the researched power generation system shows a high stability of output voltage and frequency with help of speed regulator. Biogas fuel (mainly $CH_4$ and $CO_2$) has an environmental impact and potential as a green alternative fuel for SI engine and they would not require significant modification of existing engine hardware. Output emissions of biogas-fueled engine are found to be relative low. $NO_x$ emission increases with the increase of output electric power of the power generation system.

• 한국병원경영학회지
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• 제7권4호
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• pp.57-101
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• 2002

These days, the environment of hospital marketing is changing rapidly. The level of expectation and demand of patients have become greater and more diversified, and patients have more alternatives in selecting hospitals. The standard of hospital selection and the type of using hospital have been changed, and competition among hospitals has been accelerated due to the opening of the medical market through globalization. Accordingly, differentiation strategies are critical in hospital marketing. The quality of medical service oriented toward patient satisfaction becomes a strong strategic weapon to secure a hospital's competitive advantage. Therefore, marketing and communication strategies should be focused on patient-oriented, rather than hospital-oriented. Considering the changes in the hospital environment and the increase in the patients' expectation level, this study categorizes doctors' communication styles into four different ones: trust-type, professional-type, cooperation-type, and control-type. The effects of these communication styles on patient satisfaction were empirically examined. The moderating roles of the patient's characteristics and clinical characteristics between the doctors' communication styles and patient satisfaction were also investigated to find out managerial implications for hospital management. To achieve such goals, data were collected from patients of 12 general hospitals in Busan. The data were analyzed to test research hypotheses that examine 1) the relationships between doctors' communication styles and patient satisfaction, 2) the moderating roles of the patient characteristics and clinical characteristics in the research model, and 3) the impact of patient satisfaction on positive word-of-mouth and repurchase. The following summarizes the major results of this research. First, the data showed that patient satisfaction varied across doctors' communication styles. Trust-type style had the strongest impact on patient satisfaction while control-type style had the weakest influence on patient satisfaction. Professional-type style and cooperation-type style also had positive effects on patient satisfaction but the impact of the two are not statistically different. Second, significant differences in terms of patient satisfaction were found depending upon demographic variables such as gender, marital status, age, occupation, and education. Patient satisfaction, however, was consistent across varying income groups. Third, patients' medical insurance types were also related to patient satisfaction. It implies that a doctor may need to use different communication styles depending on a patient's medical insurance type. Fourth, out-patient and in-patient showed a different level of satisfaction with varying communication styles. Fifth, highly professional knowledge and strong control can influence patient satisfaction depending on the characteristics of the patient treatment field. Sixth, patient satisfaction were proved to have significantly positive effects on word-of-mouth and repurchase. The implications drawn from this study must be tempered by its limitations. First of all, the subjects used in this study were patients in Busan and small- and medium-size hospitals were excluded from the research. Therefore, future research should examine the research model by using a variety of hospitals and clinics throughout Korea. Another research agenda has to do with finding more determinant and moderating variables which will increase an explanatory power of the model. In short, this study may be the first empirical research that investigates the effects of doctors' communication styles on patient satisfaction. Interestingly enough, the results showed that each communication style had a unique impact on patient satisfaction. The findings from this research can be very useful in developing hospital marketing strategies.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.25-30
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• 2011

In this paper, we analyzed the electrical characteristics with Micro-cracks in Photovoltaic module. Micro cracks are increasing the breakage risk over the whole value chine from the wafer to the finished module, because the wafer or cell is exposed to mechanical stress. And The solar cells have to with stand the stress under out door operation in the finished module. Here the mechanical stress is induced by temperature changes and mechanical loads from wind and snow. So, we experimentally analyze the direct impact of micro-cracks on the module power and the consequences after artificial aging. The first step, we made micro-cracks in PV module by mechanical load test according to IEC 61215. Next, PV modules applied the thermal cycling test, because micro-cracks accelerated aging by thermal cycling test, according to IEC61215. Before every test, we checked output and EL image of PV module. As the result of first step, we detected little power loss(0.9%). But after thermal cycling test increased power loss about 3.2%.

• Earthquakes and Structures
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• 제23권3호
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• pp.245-257
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• 2022

This study is a basic study on the seismic reinforcement method of anchors of fixed parts in order to reduce the effect of seismic motion that affects the facilities in the event of an earthquake. By applying the test method of ICC ES AC 156, a seismic simulation experiment was performed on the vibration table with three axes simultaneously using the number of connecting bolts between cabinets and channels as a parameter. In addition, the reliability of the experiment was verified using numerical analysis, and the part about the dynamic characteristics that could not be performed according to the experimental limit was investigated through numerical analysis. As a result of the experiment, it was confirmed that the natural frequency of the main body was increased due to the increase in the number of connecting bolts between the cabinet-channel. Accordingly, it was judged that the rigidity of the lower part of the cabinet was increased due to seismic reinforcement. It was analyzed that the impact delivered to the body was effectively reduced. In the future, if the reinforcement of the connection parts mentioned in this study is added to the existing seismic reinforcement of the electrical cabinets, it is expected that the damage to the electrical cabinets of the power plant equipment caused by an earthquake will be effectively reduced.

• The Journal of Asian Finance, Economics and Business
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• 제7권7호
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• pp.85-93
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• 2020

In peer-to-peer (P2P) loan markets, as most lenders are unskilled and inexperienced ordinary individuals, it is important to know the characteristics of borrowers that significantly impact their repayment performance. This study investigates the effects and importance of borrowers' past repayment performance track record within the platform to identify its predictive power. To this end, I analyze the detailed loan repayment data from two leading P2P lending platforms in Korea using a Cox proportional hazard, multiple linear regression, and logit models. Furthermore, the predictive power of the factors proxied by borrowers' track records are evaluated through the receiver operating characteristic (ROC) curves. As a result, it is found that the borrowers' past track record within the platform have the most important impact on the repayment performance of their current loans. In addition, this study also reveals that the borrowers' track record is much more predictive of their repayment performance than any other factor. The findings of this study emphasize that individual lenders must take into account the quality of borrowers' past transaction history when making a funding decision, and that platform operators should actively share the borrowers' past records within the markets with lenders.