• 한국농공학회논문집
• /
• 제47권2호
• /
• pp.45-52
• /
• 2005

Biomass is one of the most competitive renewable energy resource and can be used for heating for rural applications. A economic assessment was made of biomass heating, using the tool BIOH2000 from $RETScreen^{\circledR}$ International Clean Energy Decision Support Centre. For a 260kW heating system for 50 farm houses, the assessment showed a very promising results. Internal rate of return was $19.7\%$ and year-to-positive cash flow was 5.1 years. Relative price of biomass over fossil fuel significantly affected the economic feasibility of the project. Heating demand was directly related to annual demand of biomass and economic feasibility. Relative cost of distribution pipe over the total initial costs also affected the economic feasibility of the project. The economic feasibility was expected to be improved by the probable greenhouse emission reduction credit and reduction of initial costs through utilizing existing heating system for peak or back up heating system.

• 한국산학기술학회논문지
• /
• 제22권4호
• /
• pp.150-159
• /
• 2021

본 논문에서는 충전 시 발생하는 누전차단기 Trip으로 충전 중단에 의한 전기자동차 사용자의 불편함을 방지하기 위한 것이다. 현장 사례연구로 충전기 고장(failure) 유형, 차종별 누설전류 측정실험, 누전차단기 동작 실험 시 여름철 충전기 내부 온도가 60 ℃이상까지 상승하여 누전차단기가 정격 감도 전류의 80%에서 Trip으로 충전 중단됨을 확인하였다. Joule Heating 모델링을 통하여 32A 전류를 초기 시간 t=0 (s)의 기준온도 30℃에서 통전하여 t=3000 (s)경과 후에는 누전차단기 충전부 주위에서 발열이 32.4℃까지 증가함을 시뮬레이션으로 확인하였으며, 통계 검증 tool을 활용하여 온도 및 시간(s) 요인이 발생 열량에 상관관계 0.97로 검증되었다. 본 논문의 연구 실험 결과는 충전기 기구 물 개발 시 충전케이스의 재질, 내부 배선의 배치, 유전 매질에 따른 Joule Heating 시뮬레이션 수행으로 여름철 충전기 내부 온도 상승에 의한 누전차단기 감도 전류 Trip을 방지할 수 있음을 알 수 있었다.

• 한국군사과학기술학회지
• /
• 제21권4호
• /
• pp.464-470
• /
• 2018

A development of one-dimensional thermal analysis tool is performed to estimate the thickness of cork insulation for flight vehicle. In the calculation of cork temperature, the cork density model, heat of ablation and pyrolysis gas enthalpy model were applied. The calculation for the two-layer model of cork and metal was performed by the tool and compared with the experimental data. The results for the two aerodynamic heating conditions were 17 % and -12 % different from the experimental data, respectively. The effect of mechanical ablation not included in the calculation can be expected as the cause of the difference. The temperature-density curve of cork which adjusted by experimental data was also presented.

• 설비공학논문집
• /
• 제25권12호
• /
• pp.693-699
• /
• 2013

This paper describes a method for size optimization of the major design variables for solar water heating systems at the stage of concept design. The widely used RETScreen simulation tool was used for optimization. Currently, the RETScreen tool itself does not provide a function for optimization of the design parameters. In this study, an optimizer was combined with the software. A comparative study was performed to evaluate the RETScreen-based approach with the case study of a solar heating system in an office building. The optimized results using the RETScreen model were compared to previously published results with the TRNSYS model. The objective function of the optimization is the life-cycle cost of the system. The optimized design results from the RETScreen model showed good agreement with the optimized TRNSYS results for the solar collector area and storage volume, but presented a slight difference for the collector slope angle in terms of the converged direction of the solutions. The energy cost, life-cycle cost, and thermal performance regarding collector efficiency, system efficiency, and solar fraction were compared as well, and the RETScreen model showed good agreement with the TRNSYS model for the conditions of the base case and optimized design.

• 국제학술발표논문집
• /
• The 6th International Conference on Construction Engineering and Project Management
• /
• pp.540-543
• /
• 2015

Solar energy is one of the most important alternative energy sources which have been shown to meet high levels of heating and cooling demands in buildings. However, the efficiencies to satisfy these demands using solar energy significantly vary based on the characteristics of individual building. Therefore, this paper is focused on developing the methodology which can help to design optimal solar system for heating and cooling to be in cooperated within the existing buildings according to their load profiles. This research has established the Solar Heating and Cooling (SHC) system which is composed of collectors, absorption chiller, boiler and heat storage tank. Each component of SHC system is analyzed and made by means of Modelica Language and Pistache tool is verified the results. Sequential approximate optimization (SAO) and meta-models determined to 15 design parameters to optimize SHC system. Finally, total coefficient of performance (COP) of the entire SHC system is improved approximately 7.3% points compared to total COP of the base model of the SHC system.

• 한국생산제조학회지
• /
• 제19권5호
• /
• pp.710-715
• /
• 2010

This study developed an automatic tool change system of the SMA-based tool clamping device for applications of micro-machine tools. This paper first describes clamping and unclamping procedures of the automatic tool change system and its basic configuration. Second, it presents fabrication techniques of components, such as a heating/cooling system and a tool loader. Finally, it describes automatic tool change test conducted with a prototype in which the fabrication techniques of components were employed. As the results of the test, times needed for clamping and unclamping operations were estimated to 18(s) and 8(s) respectively. The experimental results confirm that the proposed automatic tool change system can be sucessfully applied to micro-machine tools.

• 조명전기설비학회논문지
• /
• 제29권1호
• /
• pp.47-56
• /
• 2015

Energy consumption in buildings is currently a real problem. That is why both assessment of energy performance and effective energy management including renewable energy system are essential. Thus, this paper focuses on a case study to analyze the energy performance and cooling & heating energy saving of a large scale shopping store in Daejeon city. The reference building is simulated by using TRNSYS dynamic simulation tool to examine its annual energy consumption. For annual energy analysis of building, one year energy consumption is surveyed in the field. The related study is carried out in large scale shopping store to investigate the energy consumption and energy use trend of heating, cooling, hot water, lighting, ventilation, equipments and other. The evaluation of energy performance of the geothermal heat pump system installed in a large scale shopping store is also analyzed by TRNSYS tool. From simulation results, it evaluated that the geothermal heat pump system is effective energy savings method in large scale shopping store.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2003년도 추계학술대회
• /
• pp.233-236
• /
• 2003

In this Paper, the temperature control error and cooling characteristics of inverter typ coolers are evaluated to predict application validity of coolers under heating pattern and amount The temperature control error of coolers small in 15~70% range of the max. cooling ability. At less than 15% of max. cooling ability has the inverter type cooler a basic temperature control error $\pm0.5^{\circ}C$ and acts as on/off type coolers. The inverter type cooler is unsuitable for precision temperature control under the complex heating pattern. But PID control of cooler including the heating system is an alternative for the case.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
• /
• pp.530-535
• /
• 1999

In recently, annealing process of cold rolled sheet tend to change to continuous annealing process for improving quality, saving yield. In the meantime as demand for various kind and small lot of products has been increasing, batch annealing has been appreciated for its small restriction for the operation. So, we tested on the effect for the proper heating temperatures, heating time of cycle, cooling time and total cycle time in this annealing process of hi tensile strength steel for automobile. As a result of several investigation. we confirmed for the following characteristics; In this process, we knew that 68$0^{\circ}C$ is suitable for this heating temp. cycle heating time of 38 Hr, cooling time of 31 Hr and total cycle time of 70 Hr. Still more, we could know that it is proper for cold rolling before annealing to be managed by 7 pass because of the act on high pressure.

• 한국태양에너지학회 논문집
• /
• 제23권4호
• /
• pp.11-20
• /
• 2003

This study aims to develop the program for active solar heating system design & analysis. The program, named ASOLis, is consisted of three user's interface like as system input/output, library, and utilities and used TRNSYS as a calculation engine for the system analysis. ASOLis simplifies user's input data through the database and can design 37 different types of solar systems. Solar system is configurated by two separated parts "solar thermal collecting part" and "load supplying part". Due to the user-friendly layout, all design parameters can be changed quickly and easily for the influence on system efficiency. For the reliability, ASOLis compared with experimental result. As a result, ASOLis is expected to be used as a vital tool for the design and analysis of active solar heating system.