• Journal of Biosystems Engineering
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• 제16권4호
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• pp.399-407
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• 1991

In Korea, the cultivation area under the plastic greenhouse was 1,746 ha in 1975, and 36,656 ha in 1989, it shows that the greenhouse cultivation area was increased by 21 times during last 14 years. The greenhouse cultivation area of 90~93% has been kept warm with double layers of plastic film and thermal curtain knitted with rice straw, and the rest area of 7~10% has been heated by fossil fuel energy. The use of rice straw thermal curtain is inconvenient to put it on and off, on the other hand the use of fossil fuel heating system results in the increase of production cost. To solve these problems, at first the heating load and the storable solar energy in greenhouse during the winter season were predicted to design solar utilization system, secondly a solar thermal storage system filled with latent heat storage materials was developed in this study. And then finally the thermal performance of greenhouse-solar energy storage system was analyzed theoretically and experimentally.

• 한국환경농학회지
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• 제33권1호
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• pp.57-62
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• 2014

BACKGROUND: Defoliation in grapevine cultivation is practically used to improve light environment within the canopy and thereby fruit quality. Effects of defoliation in five-year-old 'Pione' grapevine during cultivation with heating were investigated to find out optimum ratio of leaf area to fruit cluster weight (L/F). METHODS AND RESULTS: The grapevines were defoliated with berry-thinning 20 days after full bloom to provide various levels of L/F. At harvest, total leaf area values of fruit bearing branches were between 0.23 and $0.60m^2$. With increasing L/F, soluble solids and anthocyanin contents curvilinearly increased ($R^2=0.76^{**}$). At L/F over $0.6m^2/kg$, soluble solids content (SSC) leveled off. With increasing L/F, titratable acidity (TA) linearly decreased ($R^2=0.87^{**}$), but the ratio of SSC to TA linearly increased ($R^2=0.86^{**}$). Anthocyanin content was significantly correlated with SSC and the ratio of SSC to TA ($R^2=0.80^{**}$ and $0.82^{**}$, respectively). When total leaf area per fruit bearing branch was maintained $0.40m^2$, soluble solids and anthocyanin contents linearly decreased ($R^2=0.79^{**}$ and $0.85^{**}$, respectively), but TA linearly increased with increasing fruit cluster weight ($R^2=0.70^{**}$). Fruit was low in quality when the L/F was below $0.6m^2/kg$. CONCLUSION: L/F is recommended to be maintained at least $0.6m^2/kg$ in 'Pione' grapevine during cultivation with heating to produce higher-quality fruits.

• 생물환경조절학회지
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• 제25권4호
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• pp.225-231
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• 2016

본 연구에서는 유리온실 경영비 절감을 위한 고효율 난방기술을 개발하기 위하여 지하수열원 히트펌프, 알루미늄 다겹보온커튼, 근권부 국소난방장치를 조합한 난방 패키지 모델을 구성하고 파프리카 재배 벤로형 유리온실에 적용 시험을 수행하였다. 적용효과 분석을 위하여 관행 경유온수보일러와 일반 보온커튼을 설치한 대조구 온실과 비교시험을 통해 온실환경, 난방비용, 작물생육 등을 검토하였다. 알루미늄 다겹보온커튼과 일반 부직포 보온커튼을 설치한 온실에 대한 무가온 조건에서의 야간온도 비교시험에서 알루미늄 다겹보온커튼 설치 온실의 온도가 일반 부직포 보온커튼 설치 온실에 비해 평균 $2.2^{\circ}C$ 더 높게 유지됨을 확인하였다. 또한 근권부 국소 난방장치를 설치한 온실에서 미설치 온실에 비해 야간 난방 중의 베드내부 근권온도가 $4.7^{\circ}C$ 더 높게 유지됨을 확인하였다. 난방패키지를 구성하는 지하수열원 히트펌프의 난방성능을 분석한 결과 지하수를 직접 열원으로 이용하는 시스템 특성상 난방성능계수는 평균 3.7로 비교적 높게 나타났다. 난방패키지를 적용한 처리구 온실과 관행 난방의 대조구 온실에 대하여 연료소비량을 계측한 결과 10a($1,000m^2$)당 대조구 온실은 경유 14,071L, 전력 364kWh를 소비하였고, 처리구는 전력 35,082kWh를 소비하여 난방비용 기준으로 대조구 온실의 비용 절감율은 87%로 나타났다. 처리구 및 대조구 온실의 작물생육을 비교한 결과 초장과 엽록소 함량에서 차이가 발생하였으나 두 온실의 난방온도가 거의 동일하므로 전체적인 생육은 큰 차이가 없는 것으로 분석되었다. 원예시설의 난방에너지 절감효과를 극대화하기 위해서는 본 연구의 난방패키지를 구성하는 개별 기술뿐 아니라 이미 개발된 고효율 공조기 이용기술, 보온성 향상기술, 온도관리 기술 등을 지역, 시설, 작목, 작형 등에 최적화하여 조합할 수 있는 추가적 패키지 모델의 개발 연구가 필요한 것으로 판단되었다.

• 한국토양비료학회지
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• 제30권4호
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• pp.357-360
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• 1997

우리나라의 전국 주요 시설재배지에 있는 비닐하우스 343동을 대상으로 시설내 공기의 아황산($SO_2$)가스 농도를 조사한 결과는 다음과 같다. 1. 하우스내 공기중 아황산($SO_2$)가스 농도는 가온하우스내 농도와 무가온 하우스농도가 유사하나 가온 하우스에서는 0.8ppm이상의 농도가 검출되었다. 2. 아황산가스는 고추재배지에서 화훼류나 오이, 토마토 재배지 보다 농도가 높고 온도가 높은 주간이 야간보다 높은 농도가 검출되었다. 3. 가온하우스의 아황산가스의 유출은 온풍기의 파손 부위와 연돌의 이음쇄 부위이며, 연돌을 통해 외부에 배출된 아황산가스가 공기 흡입으로 재유입되는 경우도 있다. 4. 환기를 하지 않은 하우스는 아황산가스 농도가 0.6ppm이나 동일한 조건에서 환기를 한 것은 0.2ppm으로 낮았다.

• 한국농공학회논문집
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• 제61권4호
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• pp.23-32
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• 2019

Increasing crop production with the same amount of resources is essential for enhancing the economy in agriculture. The first prerequisite is to understand relationships between the resources. The concept of WEF (Water-Energy-Food) nexus analysis was first introduced in 2011, which helps to interpret inter-linkages among the resources and stakeholders. The objective of this study was to analyze energy-water nexus in greenhouse cultivation by estimating reference evapotranspiration and heating load. For the estimation, this study used the physical model to simulate the inside temperature of the agricultural greenhouse using heating, solar radiation, ventilated and transferred heat losses as input variables. For estimating reference evapotranspiration and heating load, Penman-Monteith equation and seasonal heating load equation with HDH (Heating Degree-Hour) was applied. For calibration and validation of simulated inside temperature, used were hourly data observed from 2011 to 2012 in multi-span greenhouse. Results of the simulation were evaluated using $R^2$, MAE and RMSE, which showed 0.75, 2.22, 3.08 for calibration and 0.71, 2.39, 3.35 for validation respectively. When minimum setting temperature was $12^{\circ}C$ from 2013 to 2017, mean values of evapotranspiration and heating load were 687 mm/year and 2,147 GJ/year. For $18^{\circ}C$, Mean values of evapotranspiration and heating load were 707 mm/year and 5,616 GJ/year. From the estimation, the relationship between water and heat energy was estimated as 1.0~2.6 GJ/ton. Though additional calibrations with different types of greenhouses are necessary, the results of this study imply that they are applicable when evaluating resource relationship in the greenhouse cultivation complex.

• 한국유기농업학회지
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• 제8권3호
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• pp.99-109
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• 2000

제주지방에서 가을감자의 더뎅이병 방제 및 수량증대를 위해 전작물로 녹비작물(콩, clover, pioneer, orchardgrass)을 '98년 5월 21일부터 7월 28일까지 재배하여 생육최성기에 파쇄, 경운하고 P.E 투명필름(0.01mm)으로 멀칭후 터널 설치, 태양열 토양소독을 실시한 포장에 가을감자를 재배하여 생육상태를 조사한 결과는 다음과 같다. 1. 전작물로 재배한 청예수량은 pioneer BSSF(64.3MT/ha)가 가장 많았으며, 다음으로 콩((25.0MT/ha), clover, orchardgrass 순이었다. P.E 필름멀칭+터널설치중의 상승한 평균지온은 토양깊이 5cm에서 54$^{\circ}C$, 10cm에서 45$^{\circ}C$, 20cm에서 44$^{\circ}C$였다. 콩, red clover 재배구가 비닐멀칭에 의한 토양소독효과로 인하여 가을감자의 더뎅이병 발병도가 낮아지는 것으로 조사되었다. 2. 초장, 엽록소함량치, 지상부생체중, 괴경수량 등의 생육형질은 녹비작물재배 및 비닐멀칭처리에 의해 양호해지는 경향을 보였다. 콩, red clover, pioneer 855F 재배후 감자재배구가 괴경수량이 많아지는 것으로 조사되었다. 3. 가을감자 지상부 및 괴경 중의 T-N, K, Ca함량도 녹비작물재배 및 P.E 필름멀칭에 의해 높아지는 경향을 보였다. 반면에 토양중의 T-N, 유기물함량, K함량은 녹비작물재배 및 P.E 필름멀칭후에 높아졌다가 가을감자 수확후에는 시험시작전 토양의 상태로 다시 낮아지는 추세를 나타내었다

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.688-692
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• 2005

Importance of substitute energy has been increasing due to environmental issues and lack of fossil fuels. In addition, heating cost that occupies from 30 to $40\%$ of the total production cost in Korean protected cultivation needs to be reduced for profitability and global competition. But, studying on substitute energy to solve these problems has not been activated for Korean protected cultivation. Therefore, this study was conducted to develop a geothermal heat pump system for cool ing and heat ing of greenhouses at a lower cost than conventional hot air heater and air conditioner. Fundamental test of heat transfer characteristics in soil was conducted by computer simulation and controlled tests for its verification. Based on the results of the theoretical and empirical investigations, an optimum heat pump system was developed and the performance was evaluated for practical use in a greenhouse at the Pusan Horticultural Experiment Station. The system was compared with a conventional hot air heating system through a cucumber growing test and economic feasibility analysis. Results of the application test of the geothermal heat pump showed that with an initial setting of $15^{\circ}C$ the inside temperature of the greenhouse could be maintained between 15 and $17^{\circ}C$. Results of the cucumber growing test showed that there were no significant differences in average height, leaf length, leaf width, number of nods, leaf area, dry weight and yield between the plots wi th the geothermal heat pump system and a conventional hot air heater. Economic feasibility analysis indicated that the variable cost of the hot air heater could be saved $81.2\%$ using the geothermal heat pump system. It was concluded that the geothermal heat pump system might be a pertinent heating and cooling system for greenhouses because of the low operating cost and the use of environment-friendly geothermal energy.

• 설비공학논문집
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• 제22권6호
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• pp.337-344
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• 2010

Good plant-growth conditions can be achieved by means of using greenhouses. One of the main issues in greenhouse cultivation is energy savings through the development of high efficient heating and cooling system. GSHPs are one of the recommended systems to cope with this pending need. The aim of this study is to investigate the heating performance of ground source multi-heat pump system installed in a greenhouse under part load conditions. Daily average heating COP of the heat pump unit was very high by at least 7.4, because of relatively large condenser, evaporator, and mass flow rate through ground loop heat exchanger. However, the system COP, overall heating coefficient of the performance of the system with heat pump unit and GLHX, decreased drastically due to relatively large power consumption of circulating pump under part load condition. It is suggested that the technology to enhance the performance of the ground source multi-heat pump system for a greenhouse under part load conditions should be developed.

• Journal of Biosystems Engineering
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• 제43권4호
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• pp.342-351
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• 2018

Purpose: Recently, an increasing number of farms have been cultivating shiitake mushrooms using a sawdust substrate and a cooler/heater. In this study, an attempt was made to develop an environmental control system using a heat pump for cultivating high-quality shiitake mushrooms. Methods: An environmental control system, consisting of an air-to-water type heat pump, a thermal storage tank, and a radiator in a variable opening chamber, was designed and fabricated. The system was also installed in the cultivation facility of a farm cultivating shiitake mushrooms so as to compare the proposed control system with a conventional environmental control system using a cooler-condensing unit and an electric hot water boiler. Results: The uniformity of the environment was analyzed through environment measurements taken at several positions inside the cultivation facility. It was determined that the developed environmental control system is able to control the variations in temperature and relative humidity to within 1% and 3%, respectively. In addition, a maximum temperature difference of $30^{\circ}C$ (maximum of $35^{\circ}C$, minimum of $5^{\circ}C$) and a maximum relative humidity difference of 30% (maximum of 90%, minimum of 60%) can be attained within 30 min inside the cultivation facility through the cooling of the heat pump and heating of the radiator in a variable opening chamber. Thus, the developed control system can be used to cultivate high-quality shiitake mushrooms more effectively than a conventional cooler and heater. Conclusions: In comparison with a conventional environmental control system, the developed system decreased the yield of ordinary mushrooms by 65%, and increased that of high-quality mushrooms by 217%. This corresponds to a 16% increase in gross farm income. Consequently, the developed system is expected to improve the income of shiitake mushroom cultivating farms.

• 상하수도학회지
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• 제38권2호
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• pp.109-117
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• 2024

In this study, various pre-treatment methods were evaluated for microalgae separation. These methods aimed to facilitate safe, rapid, and cost-effective online imaging for real-time observation and cell counting. As pre-treatment techniques, heating, chemical hydrolysis, heating combined with chemical hydrolysis, and sonication were employed. The effectiveness of these methods was evaluated in the context of online imaging quality through experimentation on cultivated microalgae (Chlorella vulgaris and Scenedesmus quadricauda). The chemical treatment method was found to be inappropriate for improving image acquisition. The heating pre-treatment method exhibited a drawback of prolonged cell dispersion time. Additionally, the heating combined with chemical hydrolysis method was confirmed to have the lowest dispersion effect for Chlorella vulgaris. Conversely, ultrasonication emerged as a promising technique for microalgae separation in terms of repeatability and reproducibility. This study suggests the potential for selecting optimal pre-treatment methods to effectively operate real-time online monitoring devices, paving the way for future research and applications in microalgae cultivation and imaging.