• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.6
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• pp.556-565
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• 2004

We have experimented an actual solar water heating system acquiring real data for one year period. On the basis of the operation data, it is necessary to predict the system performance such as collector efficiency and solar fraction, and to analyze the economical efficiency for system optimal design. To estimate the performance of actual systems through simulation, valid modelling for components consisting of the system should be accompanied. The present study is focused on the modelling for load patterns and operating control conditions. We proposed two load models: concentration model which gathers real loads as a meaningful group and distribution model which disperses real loads with time. If grouping of the load distribution is suitable, the predicted values by the concentration model approaches to those by the distribution model close to actual load pattern apparently. As a result, both of them are in good agreement with those by experiment.

• Journal of Biosystems Engineering
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• v.28 no.2
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• pp.97-106
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• 2003

One of the obstructing factors against managing dairy fm has been heavy labor requirement for feeding dairy cows. A Power-tiller TMF mixer was developed to reduce the cost and to provide economic benefit. The TMF mixer was desisted by the feeding capacity of 20∼30 heads at a batch with various functioning systems of auger type mixer, delivery conveyer, weighing console, pipe heater type heating system, power transmission train and mounting trailer. According to the study resulted, it showed that 1,200rpm, 1,600rpm, 2,000rpm and 2,300rpm were 6ps. Bps, lops and 12ps respectively. and that reduced shaft output by 15%. On the fodder mixer attached powertiller, initial output was necessary large torque. And the heating system was maintaining uniform temperature 60$^{\circ}C$ relatively.

• Journal of Korean Institute of Industrial Engineers
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• v.4 no.2
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• pp.97-105
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• 1978

A mathematical model is developed in order to describe the network configuration and heating distribution to a Central District Heating System for an Urban Residential Community. The purpose of using this model is to optimize operating costs and to distribute heat to the Residential Community efficiently. In particular, because of the inherent nonlinearity and dual optimization of the problem a dyamic programming approach is taken. It is turned out that the optimal cost of the system is a strong non-linear function of the network. In particular, it is found that increasing N, the number of houses, may not necessarily imply increased costs. It is felt that past failure of producing economical systems may be due to the improper attention given to the network.

• KIEAE Journal
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• v.14 no.4
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• pp.47-52
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• 2014

The problem of energy consumption is more serious in university buildings than primary, middle and high school buildings. Because university buildings have generally heating and cooling systems, and various incidental facilities. In university, the library is one of the building that many people use and the most energy is spent. So, investigation on energy saving is very important and urgent. This study aims finally to present the guideline for low-energy design of University library by aiding a designer to select best solution in the side of energy-saving. In this paper, composition of space, utilization schedule and performance of construction materials are grasped, some primary factors that effect to energy saving are analyzed by energy simulation. The result of this study is as follows; First, the subject library has more cooling load than heating load because of cooling load generated during middle season. Second, green roofs is the most effective to heating load saving, but not to cooling energy. Third, outdoor air cooling is the most effective to cooling energy saving among the investigated strategies included in this study.

• Preventive Nutrition and Food Science
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• v.12 no.2
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• pp.115-118
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• 2007

Tocopherols are important lipid-phase antioxidants that are subject to heat degradation. Therefore, kinetic analyses for oxidative degradation of tocopherols as a function of temperatures and times were performed. Alpha-, gamma- and delta-tocopherols dissolved in glycerol were heated at 100${\sim}$250$^{\circ}C$ for 5～60 min. Oxidized tocopherols were analyzed by HPLC using a reversed phase ${\mu}$-Bondapak C$_{18}$-column with two kinds of elution solvent systems in a gradient mode. The degradation kinetics for tocopherols followed a first-order kinetic model. The rate of tocopherol degradation was dependent on heating temperatures. The degradation rate constants for ${\gamma}$- and ${\delta}$-tocopherols were higher than those for ${\alpha}$-tocopherol. The experimental activation energies of ${\alpha}$-, ${\gamma}$- and ${\delta}$- tocopherols were 2.51, 6.05 and 5.34 kcal/mole, respectively. The experimental activation energies for the oxidative degradation of ${\gamma}$- and ${\delta}$-tocopherols were higher than that of ${\alpha}$-tocopherol.

• Textile Coloration and Finishing
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• v.10 no.4
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• pp.7-14
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• 1998

Microwaves are high frequency radiation capable of generating very rapid, uniform and efficient heating of textile material. Microwave heated dyeing of polyester fabric was tried with different solvent systems, irradiation time and dye concentration. Microwave fixation methods were used with 100% water,30% urea, EG and DMF, respectively, pad-baths in which the padded fabrics were exposed over a heated or boiling water bath to maintain sufficient moisture content during irradiation. In order to ascertain the relation between the dyeing property of polyester fabric and the microwave irradiation condition caused by microwave heating, the K/S values and fastness properties of dyed fabrics such as light, washing and sublimation fastness were measured.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.1
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• pp.63-73
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• 1987

This research, through the analysis of existing programs, presents a simplified logical program which can show the thermal performance of a system, based only on hourly weather data and the system design data. This program is applicable for analyzing a system of direct heating or recirculation heating which may enhance the performance of an existing solar house. Using these system in the existing systems a little raise in performance. The model analysis of a $100\;m^2$ solar house in the seoul region shows that the following figures are the most efficient and suitable; 1. Installation an81e of collector: $45^{\circ}$ 2. Collector size: $34.56\;m^2$ 3. Capacity of main storage tank: $25\;m^3$

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.4
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• pp.289-296
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• 2012

The aim of this study is to investigate the performance of a heating and cooling system with aquifer thermal energy storage(ATES heat pump system) known as one of the underground thermal energy storage application systems. The ATES system was composed of heat pump unit and ATES, which was installed in a factory building located in Anseoung. The system represented very high heating and cooling performance, and showed nearly constant COP at each heating and cooling season due to the stability of EWT. The economic analysis about an ATES system and a conventional system was also executed. The conventional system adopted an air-conditioner in the summer season and a LNG boiler in the winter season. The payback period of the ATES system was estimated by 6.62 years.

• KIEAE Journal
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• v.5 no.3
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• pp.25-31
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• 2005

Computer simulations were performed for Heating Ventilating and Air-Conditioning (HVAC) systems to figure out more efficient maintenance methods for the building used for adolescent trainees. This study aims at suggesting design alternatives for optimum operation and performing life cycle cost (LCC) for each alternative. First, the capacity of the heat source equipment was determined using annual maximum heating and cooling loads. Annual loads were calculated and applied to the alternative for the purpose of calculating annual energy cost. Second, several types of data were collected to predict energy cost. Finally, the pay back period for each alternative was calculated using total cost estimation during standard duration period. This study indicates that the absorption chiller that does not occupy most part of a mechanical room, and does not need much operation cost was most economical.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.83-85
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• 2013

With an increase in the use of low rank coals in power plants, various operational issues were raised in the fuel storage and supply, combustion, boiler and flue gas treatment systems. In the fuel storage and supply system, the main issue is the self-heating propensity of low rank coals leading to spontaneous combustion in yard storage, transport and pulverization. This study evaluated the reactivity of various sub-bituminous and bituminous coals with oxygen at low temperatures by analyzing the temperature increase characteristics of coals under a constant flow rate of oxygen supply. The results were quantified to a self-heating index and the relation with the fuel properties were evaluated.