• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.466-473
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• 2007

The comparison for the performance of heating systems, district heating and separate heating and power, is carried out in terms of energy consumption and environment on the basis of real operating data. The efficiency of boiler and the heat loss within the housing are assumed with reasonable manner due to the lack of reliable data regarding those quantities. The assessment for the established criteria of previous studies is performed and the new criteria for the analysis is proposed. It is shown that the district heating system is superior to the separate heating and power system from the point of view of reduction of energy use and environment improvement. The sensitivity study for those quantities with uncertainty such as the boiler efficiency and heat loss within the housing is carried out also and the reasons for the analysis results are discussed in detail.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.6
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• pp.15-22
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• 2018

The purpose of this study was to suggest specific evaluation data for heating and DHW energy consumption characteristics through analyzing energy consumption measurement data of gas boiler in Apartment Buildings with individual heating systems. To do this, it was measured both gas flow and electricity for heating and DHW respectively, and then it was analyzed not only characteristics according to energy sources; gas and electricity, but also the effect of various factors on heating and DHW energy consumption. The result of this study were as follows. It was developed the electric energy estimation model of a gas boiler through analysis on patterns by energy sources. And the effective factors for heating and DHW energy consumption were demonstrated as follows: the area for exclusive use, the number of auxiliary heating equipments, the number of occupants, and the number of sanitary fixtures.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2185-2191
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• 2009

Wind power and photovoltaic(PV) generation systems are the fastest growing sources of renewable energy. The nonlinear devices, such as power electronic converter or inverter, of wind power and PV generation systems are the source of harmonics in power systems. The harmonic-related problems can have significant detrimental effects in the power system, such as capacitor heating, data communication interference, rotating equipment heating, transformer heating, relay misoperation and switchgear failure. There is a greater need for harmonic analysis that can properly maintain the power quality. By measuring harmonics of existing wind power and PV generation systems as harmonics modeling, the studies were made to see the harmonic impact of grid-connected wind power and PV generation systems.

• Journal of Biosystems Engineering
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• v.32 no.1 s.120
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• pp.30-36
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• 2007

Geothermal heat pump systems use the earth as a heat source in heating mode and a heat sink in cooling mode. These systems can be used for heating or cooling systems in farm facilities such as greenhouses for protected horticulture, cattle sheds, mushroom house, etc. A horizontal type means that a geothermal heat exchanger is laid in the trench buried in 1.2 to 1.8 m depth. Because a horizontal type has advantages of low installation, operation and maintenance costs compared to a vertical type, it is easy to be adopted to agriculture. In this study, to heat and cool farm facilities and obtain basic data for practical application of horizontal geothermal heat pump systems in agriculture, a horizontal geothermal heat pump system of 10 RT scale was installed in greenhouse. Heating performance of this system was estimated. The horizontal geothermal heat pump used in this study had heating COP of 4.57 at soil temperature of 14$^{\circ}C$ for depth of 1.75m and heating COP of 3.75 at soil temperature of 7$^{\circ}C$ for the same depth. The stratification of water temperature in heat tank appeared during the whole heat rejection period.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.9-20
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• 2015

The demand of renewable energy is expected to grow in the long run in spite of current stable lower oil prices. Energy consumption for heating in horticulture greenhouse is large and affects the profits of the farms. This study analyzed the availability of biomass in rural area and proposed the strategies for utilizing the biomass for greenhouse heating. Data reveal the annual average fuel consumption in greenhouses is about 78 TOE/ha. Considering biomass resource in rural areas, agricultural residues are not sufficient to meet the biomass demand from greenhouses. Therefore it is recommended to secure further biomass including wild herbaceous biomass and woody biomass from forest. Based on the conditions of biomass gasification equipment investment and fuel prices, maximum allowable price of biomass turned out about 100,000 KRW/t to be competitive to kerosine. Biomass supply chain should be established for facilitating biomass trading between biomass consumers and biomass producers such as farmers who provide crop residues. An online trading system is an example of the system where consumers who utilize biomass make payments to suppliers and get the information about the biomass. Intermediate collection storages are required to store biomass from distributed sources. Operation of biomass heating systems in demonstration greenhouses is necessary to get information to refine and further develop commercial biomass heating systems. Relatively large greenhouses are desirable to have biomass heating systems for economic viability. The location of the greenhouse farms should be selected within the area where enough biomass resources are available for feeding the biomass facility.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2019-2022
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• 2016

In the presence of an electrically conducting medical lead, radio frequency (RF) coils in magnetic resonance imaging (MRI) systems may concentrate the RF energy and cause tissue heating near the lead. A novel design for a medical lead to reduce this heating by introducing pins in the lead is presented. Peak 10 g specific absorption rate (SAR) in heart tissue, an indicator of heating, was calculated and compared for both conventional (Medtronic) lead design and our proposed design. Remcom XFdtd software was used to calculate the peak SAR distribution in a realistic model of the human body. The model contained a medical lead that was exposed to RF magnetic fields at 64 MHz (1.5 T), 128 MHz (3 T) and 300 MHz (7 T) using a model of an MR birdcage body coil. The proposed design of adding pins to the medical lead can significantly reduce the heating from different MRI systems.

• Journal of Power Electronics
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• v.12 no.6
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• pp.851-858
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• 2012

This paper presents resonant inverter tuning for current source parallel resonant induction heating systems based on a new self oscillating switching technique. The phase error is suppressed in a wide range of operating frequencies in comparison with Phase Locked Loop (PLL) techniques. The proposed switching method has the capability of tuning under fast changes in the resonant frequency. According to this switching method, a multi-frequency induction heating (IH) system is proposed by using a single inverter. In comparison with multi-level inverter based IH systems, the advantages of this technique are its simple structure, better transients and wide range of operating frequencies. A laboratory prototype was built with an operating frequency of 35 kHz to 55 kHz and 300 W of output power. The performance of the IH system shows the validity of the new switching technique.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.493-498
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• 2008

Particles or deposit formed by corrosion of the pipe material bring about bad influences on the heating systems with inconvenience, energy loss and so on. In order to obtain the non-corrosive environments, the circulation hot water should properly be treated in several ways to satisfy one or more conditions of the followings: suitable pH-level, low hardness, low oxygen content, low conductivity, low level of chlorides and sulphur compounds and low level of solid particles. This experimental study was carried out to develope the new guidelines on the optimal water quality and directions for water quality management in heating systems. As results, it was recommended that the heating water be maintained pH-level not less than 8, hardness contents as $CaCO_3$ no more than 50 mg/L, turbidity no more than 10 NTU and T-Fe contents 1 mg/L below.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.56-61
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• 2005

The induction heating is widely used not only in the industrial fields but also in the home appliances. But the conventional induction heating systems have shortcoming that it use only magnetic utensil, in this paper, heating of Aluminum sheet by full-bridge series resonant high-frequency inverter is proposed. Also, the principle of induction heating and operations of full-bridge inverter equivalent circuit are explained. The proposed inverter controls the output voltage using phase-shift irrespective of the switching frequency using phase-shift. As a result the proposed induction heating system by full-bridge resonant inverter shows the possibility that make up for the shortcoming of the conventional existing induction heating systems.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.839-841
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• 2008

The mutagenicity after heating of different sugars (glucose, fructose, galactose, and tagatose) on the non-enzymatic browning reaction in different sugars and glycine model system was investigated. The model system containing 0.2 M glycine and 0.2 M of different sugars in 10 mL water was heated at $150{\pm}5^{\circ}C$ for 30 min. After heating, degree of non-browning reaction intensity and mutagenicity using Salmonella typhimurium TA 98 were examined. Heated glycine model systems containing different sugars increased their mutgenicity ranged from 30 to 372 revertant colonies. After heating for 40 min, mutagenicity was achieved with glycine model systems containing 4 different sugars with by 145, 356, 206, and 369 revertants per plate, respectively. The glycine model systems containing fructose or tagatose were significantly (p<0.05) higher mutagenic activity than glycine model systems containing glucose or galactose after 40 min of heating. The linear regression between Maillard reaction intensity and mutagenic activities (slope=32.38, $R^2=0.93$) indicates that mutagenicity could be fully ascribed to Maillard reaction products.