• Journal of Preventive Medicine and Public Health
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• 제24권3호
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• pp.373-389
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• 1991

In order to develop the measuring tool of VDT syndrome and investigate the variables affecting the development of VDT syndrome, a questionnaire study accompanied with the evaluation of working environment was performed with 138 VDT users from six public organs in Kwangju area. The results were summarized as follows. 1. As a result of analysis with data collected by newly developed questionnaire, VDT syndrome included five factors named as eye-related component, psychological component, general body component, musculoskeletal component, and skin-related component and the estimates of the internal consistency of five factors were 0.877, 0.820, 0.796, 0.791, 0.593 respectively. 2. Variables affecting the level of eye-related symptoms were the type of main b using VDT, the total time of VDT operation per day, and the use of external filter on CRT. 3. The level of eye-related symptoms in the group using external filter was higher significantly than that in the group not using filter. 4. The past history of severe illness affected the level of psychological symptoms significantly. 5. Variables affecting the level of general body symptoms were b satisfaction and income satisfaction. 6. Variables affecting the level of musculoskeletal symptoms were the type of main job using VDT, whether majored in EDPS, the level of typewriting, b satisfaction, and the total time of VDT operation per day. 7. Age and the use of external filter were significantly related to the level of skin-related symptoms.

• 한국과학교육학회지
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• 제37권4호
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• pp.625-636
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• 2017

이 연구는 과학영재학교, 과학고, 일반고의 운영 형태 측면에서 어떤 차이가 있는지 비교하고, 이 중 고등학교 유형에 따라 차이가 큰 핵심 변인은 무엇인지 과학영재교육 수혜자의 인식을 토대로 알아보기 위한 것이다. 이를 위하여 수혜자 288명을 대상으로 고등학교 교육 경험에 대한 설문을 실시한 후 응답 결과를 졸업한 고등학교 유형에 따라 과학영재학교, 과학고, 일반고의 세 집단으로 구분하고 일원배치분산분석을 실시한 후 집단 간 차이를 비교하였다. 분석 결과는 다음과 같다. 첫째, 최대유사체계 분석기법을 활용하여 고등학교 유형별 운영형태를 비교한 결과 교육과정 및 교원 운영 관련 변인에 차이가 있음을 확인하였다. 둘째, 수혜자들의 교육경험을 토대로 과학영재학교, 과학고, 일반고의 교육과정 운영 및 교사 전문성 측면에 대한 인식을 분석한 결과 모든 영역에 걸쳐 과학영재학교일수록 만족도가 높고 과학고, 일반고로 갈수록 만족도가 낮았다. 셋째, 고등학교 유형별 운영형태에 대한 수혜자들의 인식을 비교한 결과 과학영재학교와 과학고의 운영 형태에 차이를 보이는 핵심 변인은 교육과정 측면의 교육내용, 교수-학습과정 및 학습 환경으로 나타났다. 이 연구결과는 향후 영재 교육과정 개선을 위한 기초자료로 활용될 수 있을 것으로 기대된다.

• 한국재난정보학회 논문집
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• 제16권2호
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• pp.343-352
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• 2020

연구목적: 본 연구는 소방공무원의 지진재난 대응을 위한 소방조직구성, 소방지휘능력, 여론운영 등이 조직시민행동에 미치는 영향을 파악하여 소방조직이 지진재난에 대응하기 위한 실무적 기초자료를 제공하는데 목적이 있다. 연구방법: 전국 소방공무원 159명을 대상으로 설문조사를 수행하였으며, 조사자료는 SPSS 22.0 프로그램을 이용하여 통계적 분석을 수행하였다. 연구결과: 첫째, 소방조직구성, 소방지휘능력, 여론운영 등은 조직시민행동에 정(+)의 영향을 미치는 것으로 나타났다. 둘째, 독립변인의 종속변인에 대한 상대적 기여도는 소방조직구성, 소방지휘능력, 여론운영 순서로 확인되었다. 결론: 본 연구의 분석결과를 통해 정부가 지진대응을 위해 사전에 소방조직 구성, 소방지휘능력 배양, 여론운영이 필요함을 실무적 관점에서 제시하고자 하며 향후 발생할 수 있는 재난에 대비하고자 하는 기초자료로 활용되길 기대해 본다.

• Smart Structures and Systems
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• 제16권4호
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• pp.743-758
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• 2015

This paper presents an advanced life cycle cost (LCC) analysis of a ground source heat pump (GSHP) system and suggests a smart operation mode with a thermal performance test (TPT) and an energy pile system constructed on the site of the Incheon International Airport (IIA). First, an economic analysis of the GSHP system was conducted for the second passenger terminal of the IIA considering actual influencing factors such as government support and the residual value of the equipment. The analysis results showed that the economic efficiency of the GSHP system could be increased owing to several influential factors. Second, a multiple regression analysis was conducted using different independent variables in order to analyze the influence indices with regard to the LCC results. Every independent index, in this case the initial construction cost, lifespan of the equipment, discount rate and the amount of price inflation can affect the LCC results. Third, a GSHP system using an energy pile was installed on the site of the construction laboratory institute of the IIA. TPTs of W-shape and spiral-coil-type GHEs were conducted in continuous and intermittent operation modes, respectively, prior to system operation of the energy pile. A cooling GSHP system in the energy pile was operated in both the continuous and intermittent modes, and the LCC was calculated. Furthermore, the smart operation mode and LCC were analyzed considering the application of a thermal storage tank.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권10호
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• pp.693-700
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• 2000

A direct torque control algorithm for 3-level inverter-fed induction motors is presented. Conventional voltage selection methods provoke some problems such as stator flux drooping phenomenon and undersirable torque control appeared especially at the low speed operation. To overcome these problems, a proposed method uses intermediate voltage vectors, which are inherently generated in 3-level inverters. In the proposed algorithm, both subdivision of the basic switching sectors and applications of tntermediated voltages improve the low speed operation characteristics. This algorithm basically considers applications in which direct torque controlled induction motors are fed by 3-level inverters with low switching frequency around 500Hz. An adaptive observer is also employed to bring better responses at the low speed operation, by estimating some state-variables, motor speed and motor parameters which take a deep effect on the performance of the low speed operation. Simulation and experiment results verify effectiveness of the proposed algorithm.

• 한국안전학회지
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• 제38권1호
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• pp.87-92
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• 2023

The number of unmanned light rail train operators is continuously increasing in Korea. In a failure event during an operation due to the nature of the unmanned operation, recovery is performed based on the remote control. However, if remote recovery is not feasible, safety personnel arrive at the train to resume the train operation. There are regulations on safety personnel and the suspension time of the train operation. However, there is currently no rule for safety personnel deployment. Currently, railway operating organizations operate in three scenarios: safety personnel on board trains, stationed at stations, and deployed at major stations. Four major factors influence the downtime for each emergency response scenario. However, these four influencing factors vary too much to predict results with simple calculations. In this study, four influencing factors were considered as random variables with high uncertainty. In addition, the Monte Carlo method was applied to each scenario for the safety personnel deployment to predict train service downtime. This study found a 17% difference in train service suspension by safety personnel deployment scenario. The results of this study can be used in setting service goals, such as standards for future safety personnel placement and frequency of service interruptions.

• 경영과정보연구
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• 제17권
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• pp.107-133
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• 2005

The purpose of this study was to analyze a trend of profitability classified by characteristics of hospitals and to analyze related factors. The data for this study were derived from survey material conducted by the Korean Hospital Association on 33 hospitals in Korea between 1993 and 2002. Profitability was measured in the aspect of investment profit rate and operation profit rate with net profit to total assets, normal profit to total assets and operating margin to gross revenue as dependent variables. Independent variables were classified by general factors (ownership, number of beds, period of establishment, region), financial factors (total asset turnover, liabilities to total assets, current ratio, fixed ratio, inventories turnover, personnel costs per operation profit, material costs per operation profits), composition of manpower and facilities(personnel and area per beds), productivity index(the number of daily patients per medical doctor, the number of daily patients per nurse), the score of quality assurance activities. First, Concerning the specialists per beds or area per beds and profitability of hospitals there was not statistically significant. Second, Those hospitals having the most daily patients per nurse had significantly higher profitability than the others, but the number of daily patients per medical doctor had little effect on the profitability. Thirds, Those hospitals having a higher proportion total asset turnover tended to show significantly higher profitability compared to other hospitals, but the liabilities to total assets and liquidity ratio had a little difference to the profitability. Those hospitals having a higher proportion personnel costs per operation profit and material costs per operation profits tended to show significantly lower hospital profitability compared to other hospitals. Fourth, In regression analysis, hospital profitability had negative relationship with personnel costs per operation profit or material costs per operation profits. While it had positive relationship with total asset turnover, the number of daily patients per nurse. In conclusion, private hospitals had higher profitability than that of public hospitals. Though factors related to profitability of hospital were different according to ownership, it is important for securing appropriate profitability by operating appropriate number of nurse, raising total asset turnover, and reducing personnel costs, material costs per operation profits. This study can be used as a baseline data for planning of hospital management. But the study may be limited in that the results cannot be generalized due to its small sample size. However, this longitudinal observation of 33 hospitals over ten year period has significant merit alone.

• Journal of Information Technology Applications and Management
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• 제23권4호
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• pp.83-100
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• 2016

In this paper, we present the DEA (Data Envelopment Analysis) application case study to investigate the regionally distinctive telco management characteristics of the Asia-Pacific countries. This study attempts to exploit the implications of DEA for the assessments of core process capabilities of telcos. Accordingly, we extract input variables of CAPEX (capital expenditure), operating expense, marketing expense, and number of employees, each to reflect the competitiveness of the core processes such as fixed asset utilization, operation & sales efficiency, and white collar productivity. In conjunction with the input variables, the output variables are chosen as EBITDA (Earnings Before Interest, Taxes, Depreciation and Amortization), ARPU (Average Revenue per User), and number of subscribers. The computational testing results, conducted with total 37 telcos of the 12 Asia-Pacific countries, are analyzed in various ways to understand the distinctive performance characteristics across the region. The managerial implication captured from this study provides useful insight for using DEA as the international telco management purpose.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.311-314
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• 2004

The housing of the fuel injector supports the rod, the niddle valve and the solenoid. Based on the procedure of process design, in this paper, the forming operation is designed by the rigid-plastic finite element method. The metal flow during the forming of the fuel injector housing is axisymmetric until the final forming process. The response surface method has been performed to reduce the under-fill and the maximum effective strain. From the results of RSM, the second order regression model of equation is calculated by the least square method and used to determine the optimal values of design variables by simultaneously considering the responses. It is noted that upper under-fill is affected by the design variables of the $2^{nd}$ forming process and lower under-fill is affected by the design variables of the 1st forming process.

• International Journal of Korean Welding Society
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• 제3권2호
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• pp.15-23
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• 2003

A genetic algorithm was applied to an arc welding process to determine near optimal settings of welding process parameters which produce good weld quality. This method searches for optimal settings of welding parameters through systematic experiments without a model between input and output variables. It has an advantage of being able to find optimal conditions with a fewer number of experiments than conventional full factorial design. A genetic algorithm was applied to optimization of weld bead geometry. In the optimization problem, the input variables were wire feed rate, welding voltage, and welding speed, root opening and the output variables were bead height, bead width, penetration and back bead width. The number of level for each input variable is 8, 16, 8 and 3, respectively. Therefore, according to the conventional full factorial design, in order to find the optimal welding conditions, 3,072 experiments must be performed. The genetic algorithm, however, found the near optimal welding conditions from less than 48 experiments.