• Journal of Bio-Environment Control
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• v.6 no.4
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• pp.235-241
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• 1997

This study was performed to investigate the behaviour of root zone environments under the control of soil temperature and tension of soil moisture near the root Bone of 'Kyoho' grapes tree grown on restricted root zone system in plastic greenhouse. Maximum diurnal air temperature inside plastic greenhouse ranged between 25.1 and 32.7$^{\circ}C$, and the average of nocturnal air temperature inside plastic greenhouse maintained at 18$^{\circ}C$ in winter season. Also the minimum diurnal relative humidity ranged between 50 and 55%, and the maximum nocturnal relative humidity ranged between 84 to 87%. At a depth of 15cm from soil surface, the average soil temperature maintained at 25.6$^{\circ}C$ for under-ground heating, and appeared to 17.4$^{\circ}C$ for unheated condition. Although the tension of soil moisture just after irrigation sharply decreased to pF 1.5, the tension of soil moisture at the depth of 15cm maintained at pF 2.0~2.2. It is suggested that the tension of soil moisture at the depth of 15cm might be used as the standard for the determination of irrigation set point. Effective drainage system is needed to prevent the spindly and succulent growth of vine trees grown in restricted root zone system.

• FLOWER RESEARCH JOURNAL
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• v.18 no.3
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• pp.186-192
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• 2010

An infrared heating system, installed in a small venlo-type glasshouse ($280m^2$) in Gyeongsang National University, Jinju, Korea, was used to investigate its heating effect with potted Phalaenopsis, Schefflera arboricola 'Hongkong', Ficus elastica 'Variegata', and Rosa hybrida 'Yellow King' as the test plants. Temperature changes in test plants with the system turned 'On' and 'Off' were measured by using an infrared camera and the consumption of electricity by this infrared heating system was measured and analyzed. In potted Phalaenopsis, when the set air temperature of the greenhouse was $18^{\circ}C$, temperature of leaves and the growing medium were $22.8{\sim}27^{\circ}C$ and $21.3{\sim}24.3^{\circ}C$, respectively. In such tall plants as Schefflera arboricola 'Hongkong' and Ficus elastica 'Variegata', the upper part showed the highest temperature of 24.0 and $26.9^{\circ}C$, respectively. From the results of temperature change measurements, the plant temperatures were near or above the set point temperatures with some fluctuations depending on the position or distance from the infrared heating system. When air temperature between night and dawn dropped sharply, plant temperatures were maintained close to the set temperature ($18^{\circ}C$). There was a significant difference between 'On' and 'Off' states of the infrared heating system in average temperatures of root zone and leaf: 21.8 and $17.8^{\circ}C$ with the system 'On' and 20.4 and $15.5^{\circ}C$ with the system 'Off', respectively, in a cut rose Rosa hybrida 'Yellow King'. The heating load was about $24,850{\sim}35,830kcal{\cdot}h^{-1}$, which comes to about 27,000~40,000 won in Korean currency when calculated in terms of the cost of heating by a hot water heating system heated by petroleum. The cost for heating by the infrared heating system was about 35% of that of a hot water heating system. With the infrared heating system, the air temperature during the night was maintained slightly lower than the set point air temperature, probably due to the lack of air tightness of the glasshouse. Therefore, glasshouses with an infrared heating system requires further investigation including the installation space of the heat-emitting units, temperature sensor positions, and convection.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.04b
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• pp.31-33
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• 2001

잠열축열 그린하우스 난방 시스템의 난방특성을 분석하기 위하여 이에 대한 열평형 이론을 정립하고 수치해석에 의하여 컴퓨터 시뮬레이션 모델을 개발하고자 잠열축열 그린하우스 난방 시스템의 열저항 회로망을 구성하였다. 그리고 그린하우스의 피복재, 내부 공기, 토양표면, 잠열 축열재와의 열평형 방정식을 구성하였으며, Newton-Raphson반복법을 이용하여 수치해석을 하였고, 실험 분석을 통하여 수치해의 타당성을 검증하였다. 시뮬레이션 모델을 위하여 C언어를 사용하였으며, 겨울철 (11월-2월)의 기후 조건이 유사한 여러 날을 선정하여 온도, 태양강도, 상대습도, 토양 수분함량 등을 자료로 하여 모델링을 하였다. 여기에 사용된 토양 조건은 사양토로 건조한 상태를 유지하였다. 이상과 같은 분석에 의하여 그린하우스내 경시적 공기온도 변화와 열전달 현상의 실험치와 이론분석 결과가 잘 일치하고 있음을 알 수 있었다.

• Environmental and Resource Economics Review
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• v.17 no.2
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• pp.419-455
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• 2008

This paper analyses the Night Thermal-storage Power Service(NTPS) from the perspective of sustainability. It investigates the economic, environmental and social aspects of NTPS, thereby reveals that NTPS triggers the inefficient use of fuel, the increase of carbon dioxide emission and the increase of cross subsidy between consumers. This paper also analyses NTPS from the perspective of energy security. It investigates how NTPS makes LNG demand volatile in winter, thus threatens our energy security. According to the analysis, NTPS directly violates two basic principles of national energy policy; Sustainability and Energy Security. To solve these problems, not only the harmonized adjustment of Heating Oil Tax and Electric Power Rates is needed to curb the rapier increase of NTPS, but also another separate policy is necessary for converting the electric heating system based on NTPS into the one based on Heating Oil.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.1
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• pp.50-63
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• 2007

The development of domestic plant specific emission factors is very important to estimate reliable national emissions management. This study, for the reason, was carried out to obtain advances emission factor for Carbon Dioxide ($CO_2$) by source-specific emission tests from the iron and steel industry sector which is well known as one of the major sources of greenhouse gases ($CO_2$). Emission factors estimated in this study were compared with those of IPCC for evaluation and they were found to be of similar level in the case of $CO_2$. There was no good information available on $CO_2$ plant specific emission factors from the iron and steel industry in Korea so far. The major emission sources of $CO_2$ examined from the iron and steel manufacturing precesses were a hot blast stove, coke oven, sintering furnace, electric arc furnace, heating furnace, and so on. In this study, the concentration of $CO_2$ from the hot blast stove process was the highest among all processes. The $CO_2$ emission factors for a ton of Steel and Iron products (using B-C oil) were estimated to be 0.315 $CO_2$ tonne (by Tier 3 method) and 4.89 $CO_2$ tonne. In addition, emission factor of $CO_2$ for heating furnace process was the highest among all process. Emission factors estimated in this study were compared with those of IPCC for evaluation and they were found to be of similar level in the case of $CO_2$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.476-482
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• 2019

Regulatory protocols such as the Convention on Climate Change and the regulation of greenhouse gas emissions act as catalysts for the development of high-efficiency energy equipment and the efficient use of energy. Among the fields where energy consumption is high, the electric heating equipment is not efficient. The electric boiler mainly uses a method of circulating water by contacting the heater. When the existing electric boiler is used, the water minerals are contacted with the high-temperature heater to be carbonized and adsorbed, thereby promoting the corrosion of the heater and lowering the efficiency of the heater. For this reason, an electric induction boiler, which has high energy efficiency and is applied to an induction heating system that can uniformly heat the object to be heated rather than conduction or convection heating, is in the limelight. This method induces a boiler pipe And it is recognized as an alternative that can solve the problem that occurs when heating is performed by direct heating. Despite the fact that research on induction heating has been conducted for a relatively long period of time, there have been few studies on the electrothermal technology using induction heating. Therefore, in this paper, to improve the heat efficiency of electric induction boiler, the influence of the cross sectional area, number of windings and winding layers is analyzed by finite element method through parametric study method. The method of finding the design point which maximizes the total loss is proposed by the alternating winding design method which can maximize the heat generation by analyzing copper and iron losses.

• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.166-172
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• 2018

This study set out to conduct a field survey with smart greenhouse-based farms in seven types to figure out the actual state of smart greenhouses distributed across the nation before selecting a system to implement an optimal greenhouse environment and doing a research on higher productivity based on data related to crop growth, development, and environment. The findings show that the farms were close to an intelligent or advanced smart farm, given the main purposes of leading cases across the smart farm types found in the field. As for the age of farmers, those who were in their forties and sixties accounted for the biggest percentage, but those who were in their fifties or younger ran 21 farms that accounted for approximately 70.0%. The biggest number of farmers had a cultivation career of ten years or less. As for the greenhouse type, the 1-2W type accounted for 50.0%, and the multispan type accounted for 80.0% at 24 farms. As for crops they cultivated, only three farms cultivated flowers with the remaining farms growing only fruit vegetables, of which the tomato and paprika accounted for approximately 63.6%. As for control systems, approximately 77.4% (24 farms) used a domestic control system. As for the control method of a control system, three farms regulated temperature and humidity only with a control panel with the remaining farms adopting a digital control method to combine a panel with a computer. There were total nine environmental factors to measure and control including temperature. While all the surveyed farms measured temperature, the number of farms installing a ventilation or air flow fan or measuring the concentration of carbon dioxide was relatively small. As for a heating system, 46.7% of the farms used an electric boiler. In addition, hot water boilers, heat pumps, and lamp oil boilers were used. As for investment into a control system, there was a difference in the investment scale among the farms from 10 million won to 100 million won. As for difficulties with greenhouse management, the farmers complained about difficulties with using a smart phone and digital control system due to their old age and the utter absence of education and materials about smart greenhouse management. Those difficulties were followed by high fees paid to a consultant and system malfunction in the order.

• Advances in Energy Research
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• v.5 no.4
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• pp.289-304
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• 2017

Large glazed surfaces and windows become common features in modern buildings. The spread of these features was influenced by the dependence of designers on mechanical and artificial systems to provide occupants with thermal and visual comfort. Countries with hot summer and cold winter conditions, like Jordan, require maximum shading from solar radiation in summer, and maximum exposure in winter to reduce cooling and heating loads respectively. The current research aims at designing optimized double-positioned external shading device systems that help to reduce energy consumption in buildings and provide thermal and visual comfort during both hot and cold seasons. Using energy plus, a whole building energy simulation program, and radiance, Lighting Simulation Tool, with DesignBuilder interface, a series of computer simulations for energy consumption and daylighting performance were conducted for offices with south, east, or west windows. The research was based on comparison to determine the best fit characteristics for two positions of adjustable horizontal louvers on south facade or vertical fins on east and west facades for summer and winter conditions. The adjustable shading systems can be applied for new or retrofitted office or housing buildings. The optimized shading devices for summer and winter positions helped to reduce the net annual energy consumption compared to a base case space with no shading device or with curtains and compared to fix shading devices.

• Agricultural and Biosystems Engineering
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• v.6 no.2
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• pp.65-69
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• 2005

A windheat generation system with a Savonius windturbine was developed and the performance was evaluated through field tests. The system consisted of a heat generation drum, heat exchanger, water storage tank, and two circulation pumps. Frictional heat is created by rotation of a rotor inside the drum containing thermo oil, and was used to heat water. In order to estimate the capacity of this windheat generation system, weather data was collected for one year at the site near the windheat generation system. Wind Power from the savonius wind turbine mill was transmitted to the heat generation system with an one-to-three gear system. Starting force to rotate the savonius wind turbine and the whole system including the windheat generation system were 1.0 and 2.5 kg, respectively. Under the outdoor wind condition, maximum speed of the rotor in the drum was 75rpm at wind speed 6.5 m/sec, which was not fast enough to produce heat for greenhouse heating. Annual cumulative hours for wind speeds greater than 5 m/sec at height of 10, 20, 30 m were 190, 300 and 1020 hrs, respectively. A $5^{\circ}C$ increase in water temperature was achieved by the windheat generation system under the tested wind environment.

• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.294-301
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• 2018

In winter, thermal screens are widely used to reduce heat loss from greenhouse to save energy. Unfortunately, not much data are available to the farmer to compare thermal screens while selecting the one that meets their specific requirements. Thus, there is a need to investigate the thermal performance of thermal screens. To address this issue, the Building Energy Simulation (BES) model of a hot box was used to calculate the overall heat transfer coefficient (U-value) of the thermal screens. To validate the model, computed and experimental U-values of single-and double-layered polyethylene (PE) material were compared. This validated model was used to predict the U-values of the selected thermal screens under defined weather conditions. We quantified the U-values of each selected material and significant changes in their U-values were noted in response to different weather conditions. Notably, the thermal properties of the tested screens were taken from the previous literature to calculate U-values using the BES model. The U-values of the thermal screens can help researchers and farmers evaluate their screens and make pre-design decisions that suit their investment capabilities.