• 대한기계학회논문집A
• /
• 제27권4호
• /
• pp.608-613
• /
• 2003

In this paper, the effect of interconnected boundary between journal and thrust bearings on the performance of self-acting air-lubricated bearings is investigated. When journal and thrust bearings have common boundary, conventional boundary condition which assumes that the boundary pressure is equal to atmosphere is no more valid. Instead, new boundary condition by mass conservation at interconnected boundary is needed. To do this, a duct model satisfying mass conservation at interconnected boundary is developed. Using this model, pressure distribution at interconnected boundary is numerically analyzed with changing the volume of interconnecting part. As a result, it is shown that load capacity of thrust bearing can be greatly increased when journal and thrust have a common boundary.

• 자원ㆍ환경경제연구
• /
• 제9권4호
• /
• pp.773-799
• /
• 2000

The purpose of this paper is to measure the benefits of conservation of the green belt in the Greater Seoul area by CVM using dichotomous choice with a follow-up elicitation method. According to the government's plan, part of the green belt in the Greater Seoul area is to be freed from green belt designation. The mean willingness-topay(WTP) to conserve the green belt in the current state turns out to be about 7,430 won(95% confidence interval 6,220 - 8,640 won) per household, which amounts to 308 billion won per year for entire population of Seoul. This WTP figure is found to be significantly influenced by level of education, sex, and the variables related to the perception and attitudes of respondents.

• 한국태양에너지학회 논문집
• /
• 제29권2호
• /
• pp.55-61
• /
• 2009

This paper reviews the state-of-the art in surface analysis techniques for solar coatings. For analyzing solar coatings and interfaces, surface properties were very important factor for obtaining the information related to the optical degradation processes and microstructure. Various types of analytical techniques for chemical composition, microstructure and surface topography analysis of solar coatings were discussed. In addition, the examples of solar selective coating analysis results for applications were demonstrated. Development and analysis technique of solar coating for energy conservation was felt to be necessary at this time.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제9권2호
• /
• pp.62-68
• /
• 2001

It is a serous subject for energy conservation to prevent the energy loss caused by the mixture of heated and cooled air jets in perimeter and interior zone of a building operated with tow kinds of air-conditioning system simultaneously. The purpose of this paper is to clarify the quantitative and qualitative mechanisms of mixing loss and to propose a evaluation method for it. By using the dynamic heat load calculation, heat extraction load of a typical office building in Busan are calculated. According to the results, numerical simulations based on CFD(Computational Fluid Dynamics) were performed in order to evaluate mixing loss in the physical size of HVAC system. Then, the distributions of air temperature and airflow patterns according to the differences of set-point temperature are analyzed to grasp relations how to influence mixing loss.

• 보존과학연구
• /
• 통권27호
• /
• pp.215-226
• /
• 2006

In the field conservation treatment, it is important that the method chosen to lift an object out of the ground depends on its surrounding weather, strength, size, composition, and condition. This paper describes a physical support(Urethane bandage, De naturation - polyisoprene resin) created for lifting delicate relics in this field. The advantage of Urethane bandage method is of conveniently portable size, and it's convenient for use, while curing time is very fast.(approx. 5~10minute)Denaturation -polyisoprene resin is able to be soft by the hot water(approx. $60^{\circ}C$ ). so it's good to stick to the relic surface of an indeterminate form. The results of use of these reinforcement methods are of utility value.

• 한국농공학회지
• /
• 제22권4호
• /
• pp.73-81
• /
• 1980

In the light of these analysis of the recorded rainfall data from the meteorological observatories in Kyungpook area, hydraulic and hydrological data based on the representative watershed area and questionnaire or visiting letters to the 21 Land Reclamation Association in Kyungpook province, the hydrological backgrounds being the question to the irrigation facilities in Kyungpook Province or nation wide were studied partialy and the system of conservation and management of agricultural water sources facilities, prevention countermeasures to the drought and flood disasters, prediction of available surface waterflow and need or needless of new facilities establishment were reviewed in this paper. In the results, Technical and financial management and conservation investments of the already constructed ficalities should urgently and firstly be considered than the newly being established one.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제1권3호
• /
• pp.397-403
• /
• 2012

This paper describes a control method of turn-on/off angles to improve the efficiency of the switched reluctance generator(SRG) with a power closed-loop control system, and the inner-loop of the system is current hysteresis control. The SRG control system is constituted by the PI power controller and the two-level current hysteresis controller. By measuring and analyzing the system losses of different reference powers, speeds and turn-on/off angles, selection strategy of optimal turn-on/off angles is discussed. The proposed method is simple, reliable, and easy to achieve.

• 한국환경복원기술학회지
• /
• 제1권1호
• /
• pp.110-113
• /
• 1998

It can be said that the revegetation technology in Japan was started in 1960's when Japan entered into the era of high-growth economy. In the beginning, the revegetation technology was mainly applied on the man made slopes, and with the time, the fields of the revegetation technology have been extended to the urban landscaping, ecosystem conservation, prevention of desertification and so on. With the progress of the revegetation technology and the expansion of its fields, new problems have occurred. In this paper, I introduced the history of The Japanese Society of Revegetation Technology and the present condition, and discussed about the problems of the revegetation technology in Japan.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2015년도 전력전자학술대회 논문집
• /
• pp.179-180
• /
• 2015

The task of measuring losses becomes more challenging with ever increasing efficiencies and operating frequencies in power electronics applications. Generally, the process of traditional switching loss calculation in flyback converter is very complicated. MOSFET drain-source voltage and current waveforms are needed to calculate switching loss. However, as we know in switched capacitor converter, switching loss can be easily calculated by charge and energy conservation law with known initial and final capacitor voltages. In this paper, the same method is applied to fly-back converter switching loss analysis to simplify calculation procedure.

• Nuclear Engineering and Technology
• /
• 제55권1호
• /
• pp.353-363
• /
• 2023

The STELLA-2 is a large-scale sodium thermal-hydraulic integral effect test facility and supports the development of PGSFR. The facility adopted Pump Simulation Loop System (PSLS) concept for the mechanical sodium pump in the reference reactor to control and to measure the primary sodium flow. Since the component (mechanical pump) is replaced by the loop, it is very important to evaluate the similarity between the pump and the loop. In this paper, to simulate the characteristic of the mechanical sodium pump, the pressure loss along the various options of the loop was evaluated and the comprehensive validity of each design options was analyzed. Using the similarity criteria based on the Richardson number and Euler number conservation, the PSLS design was finalized and the result was within the acceptable error range. Finally, the result of this study was used for construction of the overall facility, STELLA-2.