• Journal of Bio-Environment Control
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• v.5 no.1
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• pp.79-88
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• 1996

The purpose of this research was to develop labor-saving cultural practices of cherry tomatoes in the deep flow technique (DFT) by omitting the process of raising seedling. Three cultivars, ‘Pepe’, ‘Pico’ and ‘Koko’ were propagated by the immediate setting of cuttings(lateral shoots) to the culture bed and by setting seedlings obtained by raising cuttings for 15 days, and grown in the standard and half - strength solution. 1. The immediate setting resulted in higher plants, larger number of leaves and larger leaf area during the early growth stage. And the harvest time was hastened by six days in the direct setting than that in the seedling setting. It was also earlier in ‘Pepe’, but not significant by different between two strengths of nutrient solution. 2. The average fruit weight was affected only by cultivars, but not by the type of cutting and the strength of nutrient solution. The highest yields were obtained from the immediate setting of ‘Pepe’ in other cultivars grown in the nutrient solution of standard strength. 3. Brix degree of treated cherry tomato juice was higher in ‘Pepe’ tomato cultured by immediate setting than others.

• Journal of Bio-Environment Control
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• v.24 no.1
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• pp.39-44
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• 2015

To improve crop productivity with optimal water management in soilless culture, the information of physical characteristics of the root medium including water behavior should be required. The objectives of this study were to analyze the physical characteristics including hydraulic properties of the root media commercially used and to analyze the relationships between actual moisture content and measured one by FDR sensor. The weight of the medium was measured by load cell for calculating the actual moisture content. The accuracy of the moisture content measured by FDR sensor was obtained by comparing with the actual one. The water holding capacity of the coir was lower than those of the rockwool due to the features of large and rough particles of the coir. The moisture content measured by FDR sensor showed large difference from the actual moisture contents measured by loadcell, indicating that the calibration of FDR sensor is needed before starting measurement. The optimum range of moisture content for irrigation control was narrow in the coir than the rockwool due to the lower water holding capacity and rehydration capability of the coir. The results of this study can be useful in establishing adequate irrigation strategies in the soilless culture.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.168-175
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• 1997

In greenhouse, data on evapotranspiration or water consumption is important for the rational water management, irrigation planning, thermal environment analysis, and watering automation. But little investigations have been attempted to make clear the characteristics of water consumption in greenhouse. In this paper, evapotransplrations of lettuce and cucumber by cropping systems were investigated. And the correlations among evapotranspiration, pan evaporation, solar radiation, mean air temperature, and minimum relative humidity were analyzed. Experimental cropping systems of lettuce were soil culture and NFT system. Those of cucumber were soil culture, perlite culture, and rockwool culture. Total water consumption of lettuce was 2.62$\ell$/plant in soil culture and 1.71$\ell$/plant in NFT system. That of cucumber was 45.22$\ell$/plant in soil culture, 27.45$\ell$/plant in rockwool culture and 29.06$\ell$/plant in perlite culture. Therefore total water consumption of soil culture showed higher than soilless culture.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1994.05a
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• pp.9-19
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• 1994

Hydroponics, Nutriculture, Soilless culture 라고 불리워지는 양액재배는 결코 새로운 기술은 아니지만 최근 집약적 생산을 위한 공장적 재배 등을 통해서 다시 주목을 받고 있다. 과거에는 재배관리의 어려움 때문에 전문가 이외에는 재배가 곤란했지만, 최근 재배관리의 자동화경향 때문에 비전문가에 의한 관리도 가능하게 되고 있다. 양액재배는 토양재배에 비하여 여러가지 장점을 가지고 있다. 양액관리를 위한 장치의 개선과 적용작물의 선택, 생력관리기술이 확정되었고, 연작장애 대책, 안정적 계획생산, 무공해식품의 평가가 높기 때문에 양액재배 면적은 서서히 증가하는 추세라 할 수 있겠다. (중략)

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1997.11a
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• pp.34-35
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• 1997

무토양재배에서의 효율적인 관수량 결정은 정확한 증산량에 근거한다. 작물의 생육과 환경과의 관계 분석을 위해서 실제의 재배시스템 전체를 대상으로 하여 증산량을 연속적으로 측정하는 것은 현실적으로 어려우며, 가능하더라도 대규모의 시설이 필요하다. 따라서 작물의 실제 증산량을 위해서 개체 측정 등의 대표치를 이용하는 방법이 적용되고 있다. 본 연구에서는 일반적인 증산량 측정을 위해서 정량펌프를 이용한 측정 시스템의 구축 및 이 방법을 이용하여 관수량 제어를 위한 환경과 증산량과의 관계를 분석하였다. (중략)

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1997.05a
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• pp.59-61
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• 1997

무토양재배시스템은 가급적 경량화이면서 집약적인 형태를 가지며, 환경보존차원을 위하여 밀폐형 순환식 재배시스템이 중시되고 있다. 무토양재배시스템은 DFT에서 NFT나 고형배지로 갈수록 외기의 환경변화에 대하여 비교적 근권부근의 환경변화가 크기 때문에 노출되어 있는 뿌리에 영향을 미치는 것으로 사료된다. (중략)

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1997.05a
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• pp.62-64
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• 1997

작물생육은 근권 부근의 온도와 밀접한 관계가 있다. 따라서 외부환경의 영향을 받기 쉬운 단순 경량화된 순환형 무토양재배시스템내의 양액 또는 배지의 온도 변화를 파악하여 환경조절을 통한 적정 생육환경을 조성할 수 있다면, 작물의 생산성에 기여할 수 있다. 본 연구는 순환식 무토양재배시스템의 위치별 온도 분포 및 배양액의 공급 과 온도변화와의 관계를 분석하였다.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.298-304
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• 2010

Nutrient uptake by plants and drainage ratio in culture beds can affect ion balance and concentrations of nutrient solutions in electrical conductivity (EC)-based closed-loop soilless culture. This study was conducted to analyze ion concentration changes with time and drainage ratio under EC-based nutrient control in closed-loop soilless culture for sweet pepper plants (Capsicum annum L. 'Boogie'). At first experiment, ion concentrations of the nutrient solution were periodically analysed while collected drainage was being reused by mixing with fresh nutrient solution at a dilution rate of EC $2.2\;dSm^{-1}$. Changes in ion concentrations of $K^+$, $Ca^{2+}$, $Mg^{2+}$, $NO_3^-$, $SO_4^{2-}$, and $PO_4^{3-}$ were 1.13, 5.35, 0.92, 0.9, 1.10, $0.19\;meq{\cdot}L^{-1}$, respectively. Ion balance such as $K^+$ : $Ca^{2+}$ and $SO_4^{2-}$ : $NO_3^-$ were mainly affected during the recirculation of nutrient solution. At second experiment, ion concentrations and EC of drainage were compared before and after replenishment under different four drainage ratios of 7%, 16%, 39%, and 51%. Ion ratios of the recirculated nutrient solutions such as $K^+$ : $Ca^{2+}$ for cation and $SO_4^{2-}$ : $NO_3^-$ for anion were investigated. ECs of drainage decreased with increase of drainage ratio and each ion concentration showed the same trends as EC did. Ion balances in drainage with drainage ratio were a little different from each other, but each ratio could be corrected by replenishment process. The ion balance at 7% drainage ratio was closest to initial ratio and followed by 16%, 51%, and 39% in the order. Ion balance such as $K^+$ : $Ca^{2+}$ and $NO_3^-$ : $PO_4^{3-}$ were mainly affected the correction process.

• Horticultural Science & Technology
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• v.16 no.1
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• pp.25-26
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• 1998

Nutrient supplying by a metering pump often produces the inaccuracy in the rate of inflow than expected. In this study, we developed the transpiration estimation system using the metering pump to measure the continuous supplying rate as well as to estimate the accurate transpiration rate. The system showed the stable characteristics by eliminating the fluctuations in the head loss of nutrient tank. The direct proportionality between the supplying time and the supplied nutrient solution was obtained. The exact correlation between the integrated solar radiation and the transpiration rate using the system was calculated, and correlation coefficients between the two factors were 0.98 in the NFT system and 0.92 in the aggregate system. This results suggest that the integrated solar radiation was an important factor to directly decide the supplying volume of nutrient solution in soilless culture system. The deveolped system using the metering pump in the study was able to control the supply of the nutrient solution to the crops adjusting to the variation of solar radiation.

• Journal of Bio-Environment Control
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• v.19 no.1
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• pp.12-18
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• 2010

Irrigation management methods controlled by integrated solar radiation (ISR) or drainage level sensor were evaluated in rockwool or coir bag culture as tomato (Solanum lycopersicum L.) production system. Substrate water content and drainage percentage were more stable in the drainage level sensor method than in the ISR method regardless of substrate type. Total yield and marketable yield were high in the drainage level sensor method, but not between substrates in the same irrigation management method. Sugar content was affected more by the substrate type than irrigation method. The drainage level sensor method was elucidated to be better than the ISR method regardless of substrate type.