• 대한안전경영과학회지
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• 제9권5호
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• pp.17-25
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• 2007

All of the city gas companies in Korea must employ the gas safety patrols by law. The gas safety patrols are responsible for the various tasks including daily gas pipeline patrol to prevent gas accidents. Since the size of jurisdiction varies among the city gas companies, it is very difficult to compare their efficiency for the operations of the safety patrol each other directly. The objective of this research is to develop the methodology to analyze and compare the efficiency of the safety patrol's operations among various city gas companies. Several factors that are related to the safety patrol's duty on the gas safety factors were identified and DEA(Data Envelopment Analysis) model for efficiency analysis was developed. Finally, the DEA model was applied to the collected data from six city gas companies. The less efficient city gas companies can benchmark the higher efficient city gas companies in order to improve the safety control systems.

• 센서학회지
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• 제13권3호
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• pp.230-235
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• 2004

This paper describes the design, fabrication and characteristics of a piezoelectric valve using MCA(Multilayer ceramic actuator). The MCA valve, which has the buckling effect, consists of three separate structures; MCA, a valve actuator die and an a seat die. The design of the actuator die was done by FEM modeling and displacement measurement, respectively. The valve seat die with 6 trenches was made, and the actuator die, which is driven to MCA under optimized conditions, was also fabricated. After Si-wafer direct bonding between the seat die and the actuator die, MCA was also anodic bonded to the seat/actuator die structure. PDMS sealing pad was fabricated to minimize a leak-rate. It was also bonded to seat die and SUS package. The MCA valve shows a flow rate of 9.13 seem at a supplied voltage of 100 V with a 50% duty cycle, maximum non-linearity was 2.24% FS and leak rate was $3.03{\times}10^{-8}pa{\codt}m^{3}/cm^{2}$. Therefore, the fabricated MCA valve is suitable for a variety of flow control equipment, a medical bio-system, automobile and air transportation industry.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1871-1877
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• 2009

KORAIL has been established by 1st January 2005. From organization change to KORAIL(Korea railroad Corporation), labour union and company management team has been argument for their train crews and drivers operation system. For example, train crew and driver working conditions; working hours per week, off day and duty day time, over night time working payment, current position payment, preparation time, company own lodge operation and so on. I assure that this comparison study for train crew and driver operation between KORAIL and EWS will helps to improve other korean railway companies management efficiency. In conclusion, EWS has 4$\sim$6 times more efficient employee for active operation than KORAIL per 1 freight brock-train operation. EWS has very resonable train crews and driver operation system, and self-control regulation for employee and management team with trusty. This thesis propose that korean railway companies and their own labour unions need joint research and benchmarking other oversea railway companies as like EWS.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2630-2637
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• 2020

The structure design of divertor Multi-Functional Maintenance Platform (MFMP) actuated by hydraulic system for China Fusion Engineering Test Reactor (CFETR) was introduced in this paper. The model of MFMP was established according to maintenance requirements. In this paper, Newton-Euler method and the improved virtual work principle were used, the equivalent driving force of each actuator was obtained through the equivalent Jacobian inverse matrix derived from velocity relationship among the components. The accuracy of the model was verified by ADAMS simulation. The stability control of the heavy-duty components driven by hydraulic cylinders based on Newton-Euler method and improved virtual work principle was established.

• Journal of Power Electronics
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• 제16권6호
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• pp.2005-2015
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• 2016

A high-step-up DC/DC converter for renewable energy systems is proposed. The proposed structure provides high voltage gain by using a coupled inductor without the need for high duty cycles and high turn ratios. The voltage gain is increased through capacitor-charging techniques. In the proposed converter, the energy of the leakage inductors of the coupled inductor is reused. This feature reduces the stress on the switch. Therefore, a switch with low ON-state resistance can be used in the proposed converter to reduce losses and increase efficiency. The main switch is placed in series with the source. Therefore, the converter can control the energy flow from the source to the load. The operating principle is discussed in detail, and a steady state analysis of the proposed converter is conducted. The performance of the proposed converter is verified by experimental results.

• 대한의용생체공학회:의공학회지
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• 제32권3호
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• pp.264-269
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• 2011

To increase therapeutic efficiency and biological safety, it is important to precision control of acoustic output for therapeutic ultrasound equipment. In this paper, the electro-acoustic radiation conductance, one of electroacoustic characteristics of therapeutic ultrasound equipment, was measured by the radiation force balance method according to IEC 61161 standards and the acoustic output was estimated using the electro-acoustic radiation conductance. The estimation of acoustic output was conducted to continuous wave mode and pulse wave mode of duty cycle between 20% and 80%. The differences between prediction values and measurement results are within 5% of measurement uncertainty, which is a reasonably good agreement. The results show that acoustic output controlled by electro-acoustic radiation conductance was found to be an effective method.

• 대한안전경영과학회지
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• 제11권1호
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• pp.7-14
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• 2009

Protecting an infant from a risk of accident was an absolute responsibility and duty of parents in the past. As increase in the ratio of entering kindergartens, the demand of all day program also increases. In infancy, safety concerns are higher than other periods since infants are curious about objects and environments and that have stronger impulse of the spirit of inquiry. Since baby's functioning is poor, an ability of balance maintenance and an exercise function are not sufficiently developed. Further more, they lack a cognitive power about self-control or situation. According to Korea Consumer Agency, safety accidents in infant institution have increased in 115% as 294 cases compared with 137 cases in 2004. Major causes of infant deaths are street accidents, drowning, and deaths from a fall in order. Considering this situation, we need to prevent and deal with accidents. Therefore this thesis grasp the situation and analyze an actual condition of an safety education about teachers who work in such institutions and infants who are educated in institutions to prevent from accidents and make up pleasant environments. Then, it will suggest all efficient safety education plans for infants to them.

• Human Ecology Research
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• 제54권3호
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• pp.239-250
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• 2016

This study identifies the aspects of a managers' perceived work experience in a Multicultural Family Support Center and analyzes how work experience backgrounds are formulated. In-depth interviews were conducted with 10 managers from March to September 2015 to understand managers' work experience. Descriptions from the interviews were analyzed using phenomenological research methods. The result show that their work experience can be categorized into 73 meanings, 10 subcategories, and five themes. The five themes are 'program development,' 'employees assignment optimization,' 'use and control network resources,' 'deal with changes in needs of multicultural families,' and 'supports vs. controls.' The analysis of the themes and subcategories from each theme allows us to first interpret that managers consider their significant and diversified work tasks overwhelming. Second, they find their jobs fit them and feel personally interested with a sense of duty from their work to overcome stress from heavy workloads. Third, managers put a high value on their work as a hands-on experience that is an officially authorized position from the government. Fourth, they are proud that they contribute to offering welfare services to multicultural families as members of Multicultural Family Support Centers.

• 융합보안논문지
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• 제16권3_2호
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• pp.43-54
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• 2016

우리나라 경찰은 지난 반세기동안 국내 외적인 시련을 극복하면서 질서유지자로서의 임무를 훌륭히 수행해 왔으나 최근 경찰을 둘러싼 환경은 국제화와 개방화, 민주화와 지방화, 산업화와 정보화가 급속히 전개되면서 치안수요의 폭발적 증가를 가져오고 있다. 또한 범죄유형이 날로 흉폭화 조직화 광역화 되는 추세여서 경찰 대응의 한계점과 더불어 장구 무기사용의 필요성이 대두되고 있는 실정이다. 하지만 장구와 무기 허용은 국민의 귀중한 생명을 위협할 수 있다는 선행과제로 인해 엄격하게 적용되어야 한다. 이에 본 연구에서는 기존에 경찰관들에게 지급된 장구 무기의 사용이 우리의 현실에 있어 실효성과 효과성이 있는지를 살펴보고, 일선 경찰관들의 법 집행력이 어느 범위여야 적정하고, 국민의 인권을 보호하는 경찰로서 신뢰를 받을 수 있는지를 조사하고 경찰 집행력 행사와 국민의 인권보호에 대해 방안을 제시하고자 한다.

• 전력전자학회논문지
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• 제14권3호
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• pp.235-242
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• 2009

본 논문에서는 새로운 비대칭 PWM 제어 방식의 양방향 하프브리지 컨버터를 제안한다. 제안한 컨버터는 구조가 간단하고 넓은 듀티 범위를 가지므로 연료전지와 같은 넓은 전압변동을 가지는 응용에 적합하다. 제안한 비대칭 PWM 방식은 기존의 위상각제어 방식에 비해 스위치 및 변압기의 동작전류를 큰 폭으로 낮추었고 ZVZCS와 동기 정류 방식을 적용하여 높은 효율과 전력밀도를 가질 수 있다. 기존 컨버터와의 비교 분석을 수행하였으며 실험을 통해 본 방식의 타당성을 검증하였다.