• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.176-183
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• 2009

Distributed generation(DG) of combined cooling, heat, and power(CCHP)has been gaining momentum in recent year as efficient, secure alternative for meeting increasing energy demands. This paper presents the energy performance of microturbine CCHP system equipped with an absorption chiller by modelling it in hospital building. The orders of study were as following. 1)The list and schedule of energy consumption equipment in hospital were examined such as heating and cooling machine, light etc. 2) Annual report of energy usage and monitoring data were examined as heating, cooling, DHW, lighting, etc. 3) The weather data in 2007 was used for simulation and was arranged by meteorological office data in Daejeon. 4) Reference simulation model was built by comparison of real energy consumption and simulation result by TRNSYS and ESP-r. The energy consumption pattern of building were analyzed by simulation model and energy reduction rate were calculated over the cogeneration. As a result of this study, power generation efficiency of turbine was about 30[%] after installing micro gas turbine and lighting energy as well as total electricity consumption can be reduced by 40[%]. If electricity energy and waste heat in turbine are used, 56[%] of heating energy and 67[%] of cooling energy can be reduced respectively, and total system efficiency can be increased up to 70[%].

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.2
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• pp.135-143
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• 2017

A customized CFD simulator to perform thermo-fluid dynamic simulations of an HVAC for an indoor space is presented. This simulation system has been developed for engineers studying architectural engineering, as the HVAC mechanical systems used in housings and buildings. Hence, all functions and options are so designed to be suitable that they are suitable for non-CFD experts as well as CFD engineers. A Computational mesh is generated by open-source libraries, FEMM (Finite Element Method Magnetics), and OpenFOAM. Once the boundary conditions are set, the fluid dynamic calculations are performed using the OpenFOAM solver. Numerical results are validated by comparing them with the experimental data for a simple indoor air flow case. In this paper, an entirely new calculation process is introduced, and the flow simulation results for a sample office room are also discussed.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.439-449
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• 1997

Studies have been carried out to determine the effect of sprinklers on fires typical of a number of occupancies including simulated of office furniture, supermarkets, carpet displays, libraries, video stores and liquor stores. After surveys of actual fire loads, the experiments were conducted in a specially designed sprinklered fire-calorimeter with a collecting hood 6 m x6 m leading to a vertical duct 1 m in diameter. Details of the rig are given elsewhere [1]. Only well ventilated fires were studied. Rate of heat release and production of various toxic chemicals were monitored during the tests. Both sprinklered and unsprinklered fires were used. The results were used to establish the unsprinklered burning behaviour and the fire-control effects of sprinklers. Before sprinkler operation, the rate of fire growth could be modelled as 12_fires as given in NFPA 92B (1991 Edition) [2]. It was found that operation of sprirnklers controlled but did not extinguish the fires. This was expected as parts of the fire load were shielded from the spray. Also there were significant increases in the concentration of carbon monoxide when the sprinklers operated. Sprinklers had little effect on the concentrations of other toxic products measured. The results from the tests were extrapolated to large single storey buildings for the same occupancy classes and the results used to compare the required and the available escape times for different occupancies, particularly whether the use of sprinklers would improve the chances of escape from those premises. It was found that in most of the cases studied, adequate escape times will be available without any special measures. For very rapid fire growths, however, special measures, such as availability of trained staff may be needed. Standard response sprinklers will have little impact.

• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.36-43
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• 2003

This paper provides the possibility of the district cooling system by using a LNG cold thermal energy. A liquefied natural gas provides a plenty of cooling source energy during a gasification of a liquefied natural gas. In recent, an ice thermal storage system is used for cooling a building, and a deep water source cooling system has been introduced as a district cooling system in which is used to cool the office towers and other large buildings in old and new downtown. LNG cooling energy refers to the reuse of a large body of naturally cold fluids as a heat sink for process and comfort space cooling as an alternative of conventional, refrigerant based cooling systems. Coincident with significant clean energy and operating cost savings, LNG cold energy cooling system offers radical reductions in air-borne pollutants and the release of environmentally harmful refrigerants in comparison to the conventional air-conditioning system. This study provides useful information on the basic design concepts, environmental considerations and performance related to the application of LNG cold thermal energy.

• Journal of Fisheries and Marine Sciences Education
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• v.16 no.2
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• pp.181-186
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• 2004

The current situation of heating and cooling system of the classrooms of our country is rather poor compared not only to those of the developed nation's classrooms but also in case of other buildings such as financial institutions, office compounds. In winter, especially students have been in hatred state with respect to their health due to the fact that the heater is operated by petroleum. Korea has been heavily dependent on foreign nations for the very fact of importing energy in the form of oil or natural gas. So it is important to conserve energy and the picture with respect to energy remains similar till today as it was in long past periods. The purpose of this study is to contribute actively in energy economy and facilitate towards a healthy school life of students and other institutions proving a system of extracting energy from river water and then converting it into heat which can stand as an effective alternate of expensive oil or gas. Installing oil-stove based heating system at classrooms of school could get considerable attentation in several respects. The proposed heat energy could be collected unlimitedly both in time and in amount. The stable and uninterrupted heat energy from river water, optimally utilizing the typical-regional and geographical characteristics has the potential to be long-lasting in duration, cheap in energy economy and beneficial to health as well.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.2
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• pp.136-141
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• 2021

Heating cables, widely used in office buildings, factories, streets and railways, deteriorate in electrical insulation during operation. The insulation deterioration of heating cables leads to electric discharges that can cause electrical fires. With this background, this paper dealt with a condition monitoring technique for heating cables by the analysis of discharge signals to prevent electrical fires. Insulation deterioration was simulated using an arc generator specified in UL1699 under AC operation, and the characteristic and propagation of discharge signals were analyzed on a 100 meter-long heating cable. Discharge signals produced by insulation deterioration were detected as a voltage pulse because they are as small as a few mV and they are attenuated through propagation path. The frequency spectrum of discharge signals mainly existed in the range from 70 kHz to 110 kHz, and the maximum attenuation of the signal was 84.8% at 100 meters away from the discharge point. Based on the experimental results, a monitoring device, which is composed of a high pass filter with the cut-off frequency of 70 kHz, a comparator, a wave shaper and a microprocessor, was designed and fabricated. Also, an algorithm was designed to discriminate the discharge signal in the presence of noise, compared with the pulse repetition period and the number of pulse counts per 100ms. In the experiment, the result showed that the prototype monitoring device could detect and discriminate the discharge signals produced at every discharge point on a heating cable.

• Journal of Industrial Convergence
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• v.20 no.1
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• pp.63-68
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• 2022

In schools and corporate buildings, public WiFi Access Points are installed on the ceilings of hallways. In the case of an architectural structure in which a WiFi signal enters through a steel door made of a material with high signal attenuation, Internet connection is frequently cut off or fails when the door is closed. To solve this problem, our research implements an economical and portable WiFi extender using a Raspberry Pi and an auxiliary battery. Commercially available WiFi extenders have limitations in the location where the power plug is located, and WiFi extension using the WiFi hotspot function of an Android smartphone is possible only in some high-end models. However, because the proposed device can be installed at the position where the Wi-Fi reception signal is the best inside the door, the WiFi range can be extended while minimizing the possibility of damage to the original signal. Experimental results show that it is possible to eliminate the shadows of radio waves and to provide Internet services in the office when the door is closed, to the extent that web browsing and real-time video streaming for 720p are possible.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.2
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• pp.10-21
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• 2022

A water source heat pump (WSHP) system is regarded as an energy-efficiency heating and cooling supply system for buildings due to its high energy efficiency and low greenhouse gas emissions. Recently, water sources such as river water, lake water, and raw water are attracting attention as heat sources for a heat pump system in Korea. This paper analyzed the applicability of a river water source heat pump system (RSHP). The river water temperature level was compared with the outdoor air and ground temperature levels to present applicability. In addition, the cooling and heating performance were compared through a simulation approach for the RSHP and a ground source heat pump (GSHP) applied to a large-scale office building. To compare the temperature level, the actual data were applied to the river water and the outdoor air, while the simulation results were applied to the ground circulation water. The results showed that the change in river water temperature throughout the year was similar to the change in outdoor air temperature. However, unlike the outdoor air temperature, the difference between the hourly and daily average river water temperatures was not large. The temperature level of river water was lower during the heating season and somewhat higher during the cooling season than that of the ground circulation water. Finally, the performance of the RSHP system was 13.4% lower than that of the GSHP system on an annual-based.

• Journal of the Korean Society of Food Culture
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• v.24 no.5
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• pp.467-477
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• 2009

This study was conducted to investigate and analyze food related and space related elements of popular Vietnamese restaurants in Hong Kong to identify restaurant images related to food, to examine how Vietnamese traditions are applied to such restaurants, and ultimately, to get their implications for us. Luxury Vietnamese restaurants in Hong Kong tended to be located in major office buildings and famous shopping malls in the downtown area; therefore, they were highly accessible to foreigners. In addition, most Vietnamese restaurants were quite formal in size or atmosphere. The food-related elements of the luxury restaurants reproduced traditional menus, but the table setting and service generally adopted a formal Western style setting. The presentation of foods was also creative and contemporary, to suit international customers' tastes. Regarding the spatial elements, restaurants serving traditional menus had interiors influenced by the French colonial period, while those serving contemporarily adapted menus had interiors with simple contemporary images emphasized by Vietnamese traditional decorations. These characteristics allowed foreigners from diverse countries to access the restaurants without a sense of rejection. Casual restaurants were primarily exposed to many people on busy roadsides, but they tended to be inferior in terms of size and quality. Apart from size and price level, food-related elements failed to reflect Vietnamese unique traditional characteristics. The outward appearance consisted of basic construction materials (glass, chassis, and bamboo) instead of those representing Vietnamese architecture. Additionally, the interior of the casual restaurants contained traditional elements or objects more frequently than luxury restaurants, but they looked rather disorderly and lacked harmony. Overall, the image of casual restaurants was degraded by the use of cheap and low quality finishing materials and furniture. The results of this study may be useful for organizations promoting the Branding of Korea or businesspeople and designers promoting the globalization of Korean foods.

• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.773-784
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• 2023

Since 2007, the government has been actively working to enhance the quality of public buildings, as evidenced by initiatives like the "National Basic Architecture Plan" and, since 2014, the "Building Service Industry Promotion Act." Despite these efforts, educational facilities continue to experience more frequent defects compared to large-scale apartment constructions. This study aims to analyze the primary causes of crack formation in educational facilities, employing the 2×2 MATRIX and IPA techniques to develop efficient crack prediction models. The research includes a review of relevant literature and an analysis of data from the Office of Education spanning 2019 to 2021 to pinpoint significant defects. Subsequently, 15 factors related to crack defects were identified through surveys and expert consultations. The 2×2 Matrix analysis of these factors highlighted the challenges in work processes and the effectiveness of preventative measures for crack formation, focusing on key areas for improvement. The findings from this study are anticipated to significantly contribute to the prevention and management of structural cracks in educational facilities, ensuring their long-term integrity.