• Nuclear Engineering and Technology
• /
• 제54권6호
• /
• pp.2135-2146
• /
• 2022

A nuclear energy facility is one of the most critical facilities to be safely protected during and after operation because the physical destruction of its barriers by an external attack could release radioactivity into the environment and can cause harmful effects. The barrier walls of nuclear energy facilities should be sufficiently robust to protect essential facilities from external attack or sabotage. Physical protection system (PPS) vulnerability assessment of a typical small nuclear research reactor was carried out by simulating an external attack with a tri-nitro toluene (TNT) shaped charge and results are presented. The reinforced concrete (RC) barrier wall of the research reactor located at a distance of 50 m from a TNT-shaped charge was the target of external attack. For the purpose of the impact assessment of the RC barrier wall, a finite element method (FEM) is utilized to simulate the destruction condition. The study results showed that a hole-size of diameter 342 mm at the front side and 364 mm at the back side was created on the RC barrier wall as a result of a 143.35 kg TNT-shaped charge. This aperture would be large enough to let at least one person can pass through at a time. For the purpose of the PPS vulnerability assessment, an Estimate of Adversary Sequence Interruption (EASI) model was used, which enabled the determination of most vulnerable path to the target with a probability of interruption equal to 0.43. The study showed that the RC barrier wall is vulnerable to a TNT-shaped charge impact, which could in turn reduce the effectiveness of the PPS.

• 한국비블리아학회지
• /
• 제21권2호
• /
• pp.39-56
• /
• 2010

이 연구는 공공도서관 청소년 프로그램의 현황을 조사하여 문제점을 분석하고 개선 과제를 탐색하였다. 1개 특별시와 6개 광역시의 공공도서관 중 2009년 8월 31부터 9월 4일까지 청소년 프로그램이 실시된 86개관을 대상으로 조사하였다. 이 연구에서는 청소년프로그램을 참여형, 체험형, 강좌형, 콘테스트형, 기관협력형 등 5가지 유형으로 구분하여 각 유형별 특성과 문제점을 분석하였다. 그리고 공공도서관의 청소년 프로그램의 활성화를 저해하는 제반 환경적 문제를 점검하고 발전 방안을 제안하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 추계학술대회 논문집
• /
• pp.585-586
• /
• 2010

• 한국태양에너지학회 논문집
• /
• 제22권2호
• /
• pp.11-17
• /
• 2002

This paper is concerned with the development of a new method for making, separating ice and storage floated ice by installing an evaporation plate at under-water within a storage tank. In a conventional harvest-type ice storage system, a tank saves ice by separating an ice from an installed evaporation plate, which is located above an ice storage tank as an ice storage system. Developed new harvest-type method shows good heat transfer efficiency than a convectional method. It is because the evaporation panel is directly contacted with water in a storage tank. Also, at a conventional system a circulating pump, a circulating water distributor and a piping are installed, however these components are not necessary in a new method. In this study ice storage systems are experimentally investigated to study the charge and discharge of thermal energy. The results show the applicable possibility and performance enhancement of a new type.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2009년도 추계학술대회
• /
• pp.690-691
• /
• 2009

본 논문에서는 하이브리드용 충방전 전지에 들어갈 2차전지 충방전 시스템을 설계하고 이를 안정적으로 모니터링 하는 시스템을 개발 목표로 한다. 본 연구에서는 충방전 시스템에 대한 하드웨어 모듈과 소프트웨어 개발을 포함하고 있으며, 충방전 상태를 안정적으로 제어하여 효율적인 시스템 관리가 가능할 수 있도록 설계하였다.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 하계학술발표대회 논문집
• /
• pp.288-293
• /
• 2008

The cooling load in winter is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. The development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a multi-heat pump with 3-piping system was investigated as a function of refrigerant charge and its performance was analyzed in cooling mode, heating mode, and heat recovery mode. COP in the heating or cooling mode showed little dependence on refrigerant charge at overcharge conditions, while those were strongly dependent on refrigerant charge at undercharge conditions and outdoor inlet temperature. In the heat recovery mode, the performance of the system was very sensitive to charge amount at all conditions. Optimum charge amount in the heat recovery mode was 14% lower than that in the cooling mode at the standard condition because the refrigerant only passed the indoor units. It is required to store the excessive refrigerant charge in a storage tank to optimize the system performance at operating modes.

• 한국입자에어로졸학회지
• /
• 제10권1호
• /
• pp.27-31
• /
• 2014

A simple bimodal model has been developed to analyze charged particle coagulation by modifying previously suggested bimdal model for evolution of particle generation and growth. In the present model, two monodisperse modes are used and 40 charge nodes are assigned to each mode to account both change of the particle size and charge distribution. In addition, we also implemented the effect of electrostatic dispersion loss in the present model. Based on the developed model, we analyzed coagulation of asymmetric bipolar charged particles by computing evolutions of particle number concentration, geometric mean diameter of particles, charge asymmetric ratio and geometric standard deviation of particle size distribution for various initial charge asymmetric ratios. The number concentration of asymmetric bipolar charged particles decreases faster than that of neutral particles but that does not give faster growth of particles since the electrostatic dispersion loss overwhelms particle growth by coagulation.

• Journal of Multimedia Information System
• /
• 제6권3호
• /
• pp.147-154
• /
• 2019

In a variety of fields, highly developed technology is being combined to create a lot of value. In order to keep up with this global trend, the Ministry of Education, which is in charge of national education, continuously develops and applies content for creative education to textbooks. The continuous development of content for creative education is not only related to national interests, but also to the continued development of mankind. Today, the succession and development of human knowledge is in charge of the education system. Research into an effective educational system is necessary for effective succession of rapidly developing science and technology and building up technical personnel with such skills. In particular, the computer science field is faster in development than other scientific fields and has accumulated many technologies, indicating that it takes a lot of time and good teaching to foster talent that can effectively utilize the technology. In this paper, elementary school subjects were analyzed to achieve the purpose of cultivating talent in the field of computer science. In addition, we have investigated techniques related to computer programming learning not covered in elementary school subjects. So we developed content that students need to practice. Next, we taught the content to randomly selected elementary school students and assessed their educational effectiveness. As a result of training using the content we developed, 55.37% increased academic performance.

• 농업과학연구
• /
• 제39권2호
• /
• pp.279-289
• /
• 2012

This study was conducted to survey and diagnose operation status of the agricultural machinery rental service, analyse and compare operational efficiency among 82 city and county ATDEC (agricultural technology development and extension center) using the DEA (Data Envelopment Analysis) method, and recommend future direction, for improvement of the business. Input variables were invested budget and labor, and output variable was rental return. Percentages of return to investment on the rental service were calculated as 68.3% and 63.9% when analyzed with CCR (Charnes, Cooper and Rhodes) and BCC (Banker, Charnes and Cooper) models, respectively, indicating inefficiency of the service operation. Increase of rental charge would increase efficiency by 63.9~68.3% depending on models, and decrease of financial and labor investment would improve the efficiency by about 11.3%. Technical efficiency would be more important than scale efficiency, therefore adjustment of over-invested budget and labor needed to be made together with increase of rental charge to improve the operation. Among the ATDECs providing the rental service, 6 (7.3%), 43 (52.4%), and 33 (40.2%) were in state of CRS (constant return to scale), IRS (increasing return to scale), and DRS (decreasing return to scale), respectively. These indicated public aspects of the rental system, over-investment, lack of output component for input component, meaning that scale income would be increased by qualitative expand of rental charge. Efficiency analysis of the rental system by region showed that efficient ATDECs to be benchmarked by others were in the order of DMU-70, DMU-54, DMU-29, DMU-5, DMU-22, DMU-2, and DMU-61. More comprehensive and extensive survey and analyses would be necessary in the future.

• 설비공학논문집
• /
• 제20권7호
• /
• pp.492-499
• /
• 2008

The cooling load in winter is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. The development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a multi-heat pump with 3-piping system was investigated as a function of refrigerant charge and its performance was analyzed in cooling mode, heating mode, and heat recovery mode. COP in the heating or cooling mode showed little dependence on refrigerant charge at overcharge conditions, while those were strongly dependent on refrigerant charge at undercharge conditions and outdoor inlet temperature. In the heat recovery mode, the performance of the system was very sensitive to charge amount at all conditions. Optimum charge amount in the heat recovery mode was 14% lower than that in the cooling mode at the standard condition because the refrigerant only passed the indoor units. It is required to store the excessive refrigerant charge in a storage tank to optimize the system performance at operating modes.