• Smart Media Journal
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• v.12 no.10
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• pp.63-70
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• 2023

Recently, energy consumption for heating costs, which is 35% of smart farm energy costs, has increased, requiring energy consumption efficiency, and the importance of new and renewable energy is increasing due to concerns about the realization of electricity bills. Renewable energy belongs to hydropower, wind, and solar power, of which solar energy is a power generation technology that converts it into electrical energy, and this technology has less impact on the environment and is simple to maintain. In this study, based on the greenhouse heat storage tank and heat pump data, the factors that affect the heat storage tank are selected and a heat storage tank supply temperature prediction model is developed. It is predicted using Long Short-Term Memory (LSTM), which is effective for time series data analysis and prediction, and XGBoost model, which is superior to other ensemble learning techniques. By predicting the temperature of the heat pump heat storage tank, energy consumption may be optimized and system operation may be optimized. In addition, we intend to link it to the smart farm energy integrated operation system, such as reducing heating and cooling costs and improving the energy independence of farmers due to the use of solar power. By managing the supply of waste heat energy through the platform and deriving the maximum heating load and energy values required for crop growth by season and time, an optimal energy management plan is derived based on this.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.22-29
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• 2019

A heat pump system using wasted heat from thermal effluent to supply the heating energy can reduce energy consumption and emissions of greenhouse gases by greenhouse facilities nearby. The Jeju National University consortium constructed a heat pump system using the thermal effluent from the Jeju thermal power plant of KOMIPO to provide with cool or hot water to greenhouse facilities located 3 km from the power station. In this paper, the system configuration of the heat pump system was summarized, and the results of operations for demonstration of a heating performance carried out during the winter season in 2018 were investigated. The preoperational tests proved that the water temperature drop through the pipeline transporting extracted heat was less than $2^{\circ}C$. The COP (coefficient of performance) of the heat pump was higher than 4.0, and hot water with the maximum temperature of $50^{\circ}C$ could be supplied to greenhouse facilities by utilizing wasted heat from thermal effluent.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.42-46
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• 2017

As $CO_2$ emission with imprudent using fossil fuel, annual mean temperature of earth is increased in every year. Geothermal energy is inexhaustible energy resource to solve this problem. Heat pump performance and heat exchange efficiency of ground loop are important to distribute widely. Thus, this study are performed to increase heat pump performance and heat exchange efficiency of ground loop with dual expansion valves and spacer. As a results, COP of cooling & heating is obtained improvement up to 11.4% using dual expansion valves, and heat exchange efficiency is increased up to 17.5% using spacer. It will be reduced initial installation cost due to increasing heat pump performance and heat exchange efficiency of ground loop.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.1
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• pp.41-49
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• 2014

This study spatially assesses the impact of trees on residential rooftop solar energy potential using urban three-dimensional models derived from Light Detection and Ranging(LiDAR) data in San Francisco, California. In recent years on-site solar energy generation in cities has become an essential agenda in municipal climate action plans. However, it can be limited by neighboring environments such as shade from topography, buildings and trees. Of all these effects, the impact of trees on rooftop photovoltaics(PVs) requires careful attention because improper situation of solar panels without considering trees can result in inefficient solar energy generation, tree removal, and/or increasing building energy demand and urban heat island effect. Using ArcMap 9.3.1, we calculated the incoming annual solar radiation on individual rooftops in San Francisco and the reduced insolation affected by trees. Furthermore, we performed a multiple regression analysis to see what attributes of trees in a neighborhood(tree density, tree heights, and the variance of tree heights) affect rooftop insolation. The result shows that annual total residential rooftops insolation in San Francisco is 18,326,671 MWh and annual total light-loss reduction caused by trees is 326,406 MWh, which is about 1.78%. The annual insolation shows a wide range of values from $34.4kWh/m^2/year$ to $1,348.4kWh/m^2/year$. The result spatially maps the locations that show the various levels of impact from trees. The result from multiple regression shows that tree density, average tree heights and the variation of tree heights in a neighborhood have statistically significant effects on the rooftop solar potential. The results can be linked to municipal energy planning in order to manage potential conflicts as cities with low to medium population density begin implementing on-site solar energy generation. Rooftop solar energy generation makes the best contribution towards achieving sustainability when PVs are optimally located while pursuing the preservation of urban trees.

• Korean Journal of Environment and Ecology
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• v.24 no.5
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• pp.591-600
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• 2010

We estimated and compared C storages and annual $CO_2$ uptakes by 9 dominant tree species planted along the streets. DBH and age by tree species were measured in the sites selected considering the planting status and distributions of tree species, and biomass, C storage, growth rate, and annual $CO_2$ uptake were estimated for each species. As a result, L. tulipifera, M. glyptostroboides, P. occidentalis were classified into fast-growing group, P. serrulata, G. biloba, Z. serrata, S. japonica, A. palmatum showed intermediate growth rates, and P. densiflora was slow-growing. Average C storage per tree was 205kgC/tree and ranged from 518kgC/tree(L. tulipifera) to 41kgC/tree(P. densiflora). Average annual $CO_2$ uptake by urban street trees over their lifespan ranged from $7.6kgCO_2$/tree/y to $99.1kgCO_2$/tree/y and L. tulipifera was the greatest, followed by glyptostroboides and P. occidentalis, and P. densiflora was the lowest. Total annual $CO_2$ uptake by all street trees in Gyeonggi-do, estimated based on the annual $CO_2$ uptake by each species, was as small as approximately 0.67% of that by forest in Gyeonggi-do. However, urban trees are still important because forest area continues to decrease and urbanization occurs annually in Gyeonggi-do, and should be managed considering their multi-functional aspects, including mitigation of heat island effect and building energy saving(indirect $CO_2$ uptake).

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.317-323
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• 2017

In this study, the heating performance and the energy saving effect of the heat pump system using hot waste water(waste heat) of the thermal power plant discharged from a thermal power plant to the sea were analyzed. The greenhouse area was $5,280m^2$ and scale of the heat pump system was 120 RT(Refrigeration Ton), which was divided into 30 RT, 40 RT and 50 RT. The heat pump system consisted of the roll type heat exchangers, hot waste water transfer pipes, heat pumps(30, 40, 50 RT), a heat storage tank and fan coil units. The roll type heat exchangers was made of PE(Poly Ethylene) pipes in consideration of low cost and durability against corrosion, because hot waste water(sea water) is highly corrosive. And the heating period was 5 months from October to February. During the heating performance test(12 hours), the inlet water temperature of evaporator was changed from $32^{\circ}C$ to $26^{\circ}C$, and heat absorption of he evaporator was changed from 175 kW to 120 kW. The inlet water temperature of the condenser rose linearly from $15^{\circ}C$ to $50^{\circ}C$, and the heat release of condenser was reduced by 40 kW from 200 kW to 160 kW. And the power consumption of the heat pump system increased from 30 kW to 42 kW. When the inlet water temperature of condenser was $15^{\circ}C$, the heating COP(Coefficient Of Performance) was over 7.0. When it was $30^{\circ}C$, it dropped to 5.0, and when it was above $40^{\circ}C$, it decreased to less than 4.0. It was analyzed that the reduction of heating energy cost was 87% when compared to the duty free diesel that the carbon dioxide emission reduction effect was 62% by recycling the waste heat of the thermal power plant as a heat source of the heat pump system.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.717-729
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• 2005

Peak cooling load of large buildings is generally greater than their peak heating load. Internal and solar heat gains are used fur selection of adquate equipment in large building in cold winter climate like Canada and even Korea. The cost of geothermal heat exchanger to meet the cooling loads can increase the initial cost of ground source heat pump system to the extend less costly conventional system often chosen. Thermal ice storage system has been used for many years in Korea to reduce chiller capacity and shift Peak electrical time and demand. A distribution system designed to take advantage of heat extracted from the ice, and use of geothermal loop (geothermal heat exchanger) to heat as an alternate heat source and sink is well known to provide many benifits. The use of thermal energy storage (TES) reduces the heat pump capacity and peak cooling load needed in large building by as much as 40 to $60\%$ with less mechanical equipment and less space for mechanical room. Additionally TES can reduce the size and cost of the geothermal loop by 1/3 to 1/4 compared to ground coupled heat pump system that is designed to meet the peak heating and cooling load and also can eliminate difficuties of geothermal loop installation such as space requirements and thermal conditions of soil and rock at the urban area.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.570-574
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• 2010

The main function of conventional insulation materials is only to block the heat transfer and reduce heat loss from the building. On the other hand, thermal storage materials can work as an energy saver by absorbing or emitting heat within a specific temperature range. Thermal storage materials for building can maintain a constant temperature by effectively regulating the cycle of indoor temperature. As a result, we can enhance the performance of a cooling and heating system efficiently. In this study, phase change materials (PCMs) were added as thermal storage materials into gypsum boards which are extensively used for building material and we found out the thermal environmental characteristics. In addition, we checked out some problems when applying the thermal storage materials to buildings. Finally, This study set out to examine the degree of environmental-friendly characteristics of thermal storage building materials by analyzing the amount of TVOC and HCHO contents with the possibility of pollutants emission.

• Journal of Animal Environmental Science
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• v.1 no.2
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• pp.125-136
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• 1995

To use the earth heat for the pig housing, an underground heat exchanger has constructed in depth of 2.5m and 20m length. The temperature of the outlet air was max. 8 kelvin higher than that of inlet air in winter season. In spite of the -7$^{\circ}C$ outside temperature, it could keep the air temperature from the earth tube above zero degree. The heating performance was maximum in value of 3.25Wh/㎥ and average of 1.75Wh/㎥ by the airflow volume of 340㎥/h. The slope of relative humidity from outlet air has shown gentler than that of inlet air. By using the underground heat exchanger, it would be possible to prepare an relatively uniform relative humidity in the swine stalls. The temperatures on the earth, where PVC pipes are buried, have shown 10~12$^{\circ}C$ on March. This can reduce the difference between day and night temperature during this season by using the underground heat exchanger.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.311-321
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• 2019

Greenhouse farmers often use thermal screens to reduce greenhouse heating expenses during the winter, and for shade during hot, sunny days in the summer, as it is an inexpensive solution to temperature control relative to other available options. However, accurate measurements of their emitted and absorbed radiations are important for the selection of suitable screens that offer maximum performance. Material's ability to save energy is highly dependent on these properties. Limited studies have investigated the measurement of these properties under natural conditions, but they are only applicable to materials having partial porosities. In this work, we describe a new radiation balance method for determining emissive power and absorptive capacity, as well as reflectivity, transmissivity and emissivity of materials having complete and partial transparency by using pyrgeometer and net radiometer. In this study, four materials with zero porosity, were tested. The emissivity value of PE, LD-13, LD-15 and PH-20 was $0.439{\pm}0.020$, $0.460{\pm}0.010$, $0.454{\pm}0.004$, and $0.499{\pm}0.006$, respectively. All tested samples showed high emitted radiation as compared to absorbed radiation.