• Journal of Bio-Environment Control
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• v.17 no.3
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• pp.210-214
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• 2008

This experiment was carried out investigation of optimum concentration of supply nutrient solution in hydroponics of sweet pepper using coir substrates (coconut dust fiber=70% : 30%, v/v). During the growing period, it was found out that the electric conductivity (EC) would increase in proportion to the supply nutrient concentration but it was in inverse proportion to the moisture content. The pH of drainage was stable, while EC was high showing EC $7.3\;dS{\cdot}m^{-1}$ in EC $4.0\;dS{\cdot}m^{-1}$ of supply nutrient concentration. Also, standard deviation and coefficient of variation were high. Plant length was no difference by the supply nutrient concentration. Photosynthesis rate was generally high in supply nutrient concentration EC$4.0\;dS{\cdot}m^{-1}$. Fruit weight was heavy in supply nutrient concentration EC $4.0\;dS{\cdot}m^{-1}$, fruit shape was close to a regular square in supply nutrient concentration EC $3.5dS{\cdot}m^{-1}$.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.173-178
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• 2013

Experiments were conducted to investigate the optimum concentration of nutrient solution for strawberry 'Maehyang' bred domestically for exportation in hydroponics. Nutrient solutions for strawberry, which was made by Yamazaki, were supplied electrical conductivity (EC) 0.6, 0.8, 1.2, and $1.8dS{\cdot}m^{-1}$ after planting on cocopeat medium during the experiment period. Growth of shoot of strawberries did not show any statistical differences among treatments. Fruit length showed the longest in EC 0.8 and $1.2dS{\cdot}m^{-1}$, followed by 0.6 and $1.8dS{\cdot}m^{-1}$ in the first and third cluster. It showed the shortest in EC $1.8dS{\cdot}m^{-1}$ in the second cluster but there were no significant differences among treatments in the fourth cluster. Fruit diameter did not show significant differences among treatments in the first and second cluster but was the longest in the lowest concentration EC $0.6dS{\cdot}m^{-1}$ in the third cluster. The shortest was in EC $1.8dS{\cdot}m^{-1}$ in the fourth cluster. The heaviest mean fruit weight appeared in EC 0.8 and $1.2dS{\cdot}m^{-1}$, and the lightest was in EC $1.8dS{\cdot}m^{-1}$ in the first cluster and also lightest in EC $1.8dS{\cdot}m^{-1}$ but no significant differences was found among other treatments in the second & third cluster. Also the fruit weight was significantly light in plants grown in EC $1.8dS{\cdot}m^{-1}$ than $0.6dS{\cdot}m^{-1}$ in the fourth cluster. Soluble solids content of fruit was the highest in EC $0.6dS{\cdot}m^{-1}$ in all cluster. As a result, we came to the conclusion that the optimum EC for strawberry 'Maehyang' was EC 0.8 - $1.2dS{\cdot}m^{-1}$ during low temperature season. This result will be utilized as an indicator for strawberry hydroponics.

• Horticultural Science & Technology
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• v.30 no.6
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• pp.694-699
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• 2012

To examine the EC model in a culture medium, basic culture medium of Rush (2005) and EC model of Robinson and Strokes (1959) were applied analyzing the equivalence ion total amount, the EC variable of cation and anion. Following the experiential translation by Steiner (1980), 130 optimized domestic and foreign culture media for crop growth were utilized, and estimated EC model was also demonstrated. Results from basic culture medium of Rush (2005) suggests an estimated EC by equivalence ion total amount and high reliable regressive model with 0.96 y = 1.33x - 0.23 of 0.96 as value $R^2$. It was found out that the change in concentration of positive ion and anion did not differ significantly with the increase and decrease of EC, however, there occurred a slight variable range. The change brings about a bigger anion influence than the previously reported positive ion, seemingly like those based on nitride ion and sulfur ion. The above EC estimated models confirmed that with optimized 130 domestic and foreign culture media for crop growth, the value derived will be as follows: $R^2$ = 0.98 with y = 1.23x - 0.02. In addition, the contour analysis of positive ion and anion for EC, with popularly known concentration range of EC $1.5-2.5dS{\cdot}m^{-1}$ reveals an equivalent of more than $11meq{\cdot}L^{-1}$ for positive ion and $15meq{\cdot}L^{-1}$ for anion. On the other hand, the left bottom, low concentration $1.5dS{\cdot}m^{-1}$ and the right above, high concentration $2.5dS{\cdot}m^{-1}$, for both positive ion and anion existed differently in a proper culture medium concentration. This study adapted variables of both positive ion and anion of EC simultaneously, unlike in the previous culture medium by ion ratio in mutual ratio of Steiner (1980), and offers an EC model that can estimate levels or positive ion and anion in proper concentration, EC $1.5-2.5dS{\cdot}m^{-1}$, with distributed features of ions.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.11a
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• pp.176-177
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• 2001

분화용 베고니아 유묘기의 양분흡수 특성을 구명하기 위하여 광강도와 배양액 농도 처리하에 실험을 진행하였다. 엽면적은 광에 의한 차이는 크게 나타나지 않았고 양액의 농도는 EC가 1.0 dSㆍm$^{-1}$처와 1.5 dSㆍm$^{-1}$에서 0.5 dSㆍm$^{-1}$보다 높게 나타났다. 초장은 광강도가 가장 낮은 처리구에서 길었고 약 38%와 60% 차광율 처리사이에는 큰 차이가 없었다. 또한 배양액의 농도에 따라서는 EC가 1.5 dSㆍm$^{-1}$인 처리구에서 EC가 1.0 dSㆍm$^{-1}$과 0.5 dSㆍm$^{-1}$인 처리구보다 초장이 길었다. 엽의 생체중도 처리에 따라 유의적인 차이가 나타났다. 광강도가 가장 낮은 처리구에서 생체중이 가장 높았으나 엽의 건물중은 처리간 차이가 나타나지 않았다. 배양액의 농도처리에 있어서 EC가 1.0 dSㆍm$^{-1}$과 1.5 dSㆍm$^{-1}$인 처리구에서 EC가 0.5 dSㆍm$^{-1}$인 처리구보다 엽의 생체중이 높게 나타났다. 그러나 배양액의 농도는 엽의 건물중에 영향을 주지 않았다. 줄기의 생체중과 건물중은 처리간 차이가 크게 나타나지 않았다. 다량원소의 흡수율을 조사한 결과 주로 배양액의 농도가 증가함에 따라 양분의 흡수율이 증가한다는 것을 알 수 있었다. 또한 광강도의 차이에 따라서 양분의 흡수율이 영향을 받는다는 것을 알 수 있었다. 광강도가 매우 낮은 처리구에서 양액의 흡수는 적었지만 높은 양분흡수율을 보였고 이러한 특성은 각 이온의 종류에 따라 약간의 차이를 보였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.123-123
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• 2016

만곡부, 합류부 등의 복잡한 지형을 갖는 자연하천에서의 오염물의 혼합 거동에 대한 이해는 수자원의 관리에 있어서 매우 중요하다. 특히 하폐수처리장과 같은 처리시설의 방류수와 같이 연속적으로 유입되는 오염물의 경우 하천 생태계에 지속적인 영향을 끼치며, 이러한 방류수는 대부분 지류를 통해 본류로 유입되게 된다. 이러한 오염물질이 지류로부터 본류로 합류되는 초기구간(near-field)의 경우, 횡방향 및 연직방향의 혼합 거동에 대한 상세한 분석이 필요하다. 본 연구에서는 금호강과 진천천이 좌안으로부터 합류되는 낙동강 중류 구간에서의 초기 혼합 구간의 연구를 위하여 전기전도도(electrical conductivity: EC)를 이용한 농도 추적 실험을 수행하였다. 수온, 전기전도도, 이온화 물질 등과 같은 자연 추적자(natural tracers)를 이용하는 농도 추적 실험은 인공추적자 물질을 이용한 실험을 대체할 수 있는 방안으로서, 기존 추적자 실험과 비교하여 경제적, 환경적인 효과와 하폭이 넓은 중규모 이상의 하천에서도 수행할 수 있다는 장점을 가지고 있다. 실험 구간에서 합류되는 2개의 지류 모두 인근 하폐수처리장으로부터 방류수가 연속적으로 유입된다. 본류에서 정해진 측선을 따라 센서가 설치된 보트를 이용하여 실시간으로 농도, 수리량 데이터를 GPS 위치 데이터와 함께 취득하였다. 실험 수행 결과, 지류인 금호강과 진천천의 EC 농도가 합류 전 낙동강 본류의 EC 기저농도보다 더 높은 값을 나타내었다. 이후 지류가 합류된 직후의 측선에서 측정한 EC 농도분포를 분석한 결과, 연직방향의 편차가 크게 나타나는 것으로 나타났으며 특히 유량이 낮을수록 연직 방향 편차가 커지는 경향을 보였다. 전반적으로 수심이 깊은 구간의 저층부로 갈수록 전기전도도의 값이 증가하는 경향을 나타났으며 흐름방향으로 진행됨에 따라 연직 편차가 줄어드는 경향을 보였다. 횡방향 혼합의 경우 지류의 유입으로 인하여 본류 좌안 쪽에서 전기전도도의 값의 상승을 확인할 수 있었으며 하류로 이동할수록 불균등했던 전기전도도의 분포가 횡방향 혼합을 통하여 균등한 분포로 전환되는 것으로 나타났다.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.317-321
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• 2012

This study was carried out to investigate the effect of EC levels in nutrient solution on the growth of rose in coir substrate during the juvenile. Nutrient concentration were EC 0.6, 1.0, 1.4, and $1.8dS{\cdot}m^{-1}$. In spite of high concentration of nutrient solution was supplied, EC and inorganic ions content in the extract of substrate was no difference by 22 days after planting. After that, they was rapidly increased with higher concentration of nutrient solution. Number of shoot was highest in EC $1.8dS{\cdot}m^{-1}$ at 2nd growth cycle, 90 days after planting, after that was showed a tendency to increase with increasing nutrient concentration, but was no significant difference among treatment except EC $0.6dS{\cdot}m^{-1}$. Judging by results of growth of rose and contents of inorganic ion in extracts of media, our experiment suggests that the suitable nutrient concentration is EC $1.8dS{\cdot}m^{-1}$ until 90 days and then EC $1.4dS{\cdot}m^{-1}$ until 165 days after planting that is more higher than conventional nutrient concentration for absorption by coir.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.192-198
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• 2012

Experiments were conducted to investigate the optimum concentration of nutrient solution in hydroponics for strawberry 'Ssanta' bred at Gyongsangbuk-do Agricultural Research & Extension Services. Nutrient solutions for strawberry, which made by Yamazaki, were supplied EC (Electrical Conductivity) 0.6, 0.8, 1.2, and $1.8dS{\cdot}m^{-1}$ after planting on cocopeat medium during experiment period. Growth of shoot of strawberries did not show statistical differences among treatments. Fruit length showed the longest in EC $0.8dS{\cdot}m^{-1}$ in all clusters. In the second flower cluster, fruit length showed longer in EC 0.8 and $1.2dS{\cdot}m^{-1}$ than EC 0.6 and $1.8dS{\cdot}m^{-1}$. In the third flower cluster, it showed the longest in EC 0.8 and $1.2dS{\cdot}m^{-1}$, followed by 0.6 and $1.8dS{\cdot}m^{-1}$. The longest was in EC $0.8dS{\cdot}m^{-1}$ and the shortest in EC $1.8dS{\cdot}m^{-1}$ in the fourth flower cluster. Fruit diameter did not show significant differences among treatments, but longest in EC 0.8 and $1.2dS{\cdot}m^{-1}$ in all clusters. The heaviest mean fruit weight appeared in EC $0.8dS{\cdot}m^{-1}$ in all flower clusters. And heavier in EC $1.2dS{\cdot}m^{-1}$ in the second and third clusters. Also the weight was significantly light in plants grown in EC 0.6 and $1.8dS{\cdot}m^{-1}$ in the second and third cluster. Soluble solids of fruit was the highest in EC $0.6dS{\cdot}m^{-1}$ in all clusters. As the results, we came to the conclusion that the optimum EC for strawberry 'Ssanta' was EC $0.8{\sim}1.2dS{\cdot}m^{-1}$ in this experiment.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.418-423
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• 2017

In hydroponics, the nutrient solution is supplied considering the water and nutrient uptake characteristics of crops. However, as the ionic uptake characteristics are changed as a result of the weather conditions or the growth response of the crops, the root zone can not be maintained in optimal condition. In addition, the coir substrate has been used mainly for the tomato cultivation in place of the inorganic substrate, there are few studies on long-term cultivation using coir substrate. Therefore, this study was conducted to investigate the effect of EC level of irrigation solution on tomato growth and inorganic ions of root zone in soilless culture using coir. Coir substrate mixed with 5 : 5 chip and dust was used. EC level of irrigation solution was 1.0, 1.5, 2.0, and $3.0dS{\cdot}m^{-1}$. At the initial stage, $NO_3-N$, P, Ca and Mg in the drainage were lower than the irrigation level at 1.0 and $1.5dS{\cdot}m^{-1}$. However, EC $2.0dS{\cdot}m^{-1}$ or higher, all the ions except P were highly concentrated in the drainage. The average fruit weight was not significantly different between 1.0 and $1.5dS{\cdot}m^{-1}$ until 3th cluster, but from the next cluster, the higher the EC level, the smaller the weight. The number of fruit and yield to 6th cluster was the highest at $1.5dS{\cdot}m^{-1}$. From the next cluster, The yield was decreased with the higher EC level. At the early stage of growth, BER occurred only in EC $3.0dS{\cdot}m^{-1}$, but increased in all treatments with increasing irradiation. The incidence rate of EC $3.0dS{\cdot}m^{-1}$ was higher than that of the lower EC level treatment.

• Horticultural Science & Technology
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• v.29 no.1
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• pp.23-28
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• 2011

Experiments were conducted to investigate the optimum concentration of the nutrient solution in strawberry 'Sulhyang' with hydroponics in relationship between root activity and nutrient concentrations. Nutrient solutions for strawberry, made by Yamazaki, were supplied EC 0.5, 1.0, 2.0 $dS{\cdot}m^{-1}$ during experiment period. Growth of shoot and root of strawberries grown in visible plastic pot was observed during experiment. Petiole length was longest in plants grown in EC 1.0 $dS{\cdot}m^{-1}$, followed by 2.0 and 0.5 $dS{\cdot}m^{-1}$. Leaf width was longest in plants grown in EC 1.0 $dS{\cdot}m^{-1}$, followed by 0.5 and 2.0 $dS{\cdot}m^{-1}$. Fruit length, fruit diameter, fruit weight and yield were higher in EC 0.5 and 1.0 $dS{\cdot}m^{-1}$ than 2.0 $dS{\cdot}m^{-1}$ treatment but, soluble solids of the fruit did not show statistical differences among treatments. Shoot dry weight was heaviest in EC 1.0 $dS{\cdot}m^{-1}$, followed by 0.5 and 2.0 $dS{\cdot}m^{-1}$. Root dry weight was heavier in EC 0.5 and 1.0 $dS{\cdot}m^{-1}$ but significantly light in 2.0 $dS{\cdot}m^{-1}$. pH of the drainage solution was elevated in low nutrient concentration and lowered in high concentration. Also root activity was high in low nutrient concentration and low in high concentration. As a result, the optimum EC for strawberry 'Sulhyang' was EC 1.0 $dS{\cdot}m^{-1}$ in this experiment. It was confirmed that there was high relationship between root activity and pH of drainage solution. This result will be utilized as an indicator for strawberry hydroponics.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.11
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• pp.1599-1606
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• 2015

The purpose of this study was to assess the quality characteristics of Moju made with Hovenia dulcis Thunb. and its physiological effects on ICR mice. According to the sensory score, we selected Moju made with 1% Hovenia dulcis Thunb. among Moju made with 0, 0.5, 1, 5, and 10% Hovenia dulcis Thunb. Compared to Moju made without Hovenia dulcis Thunb., Moju made with 1% Hovenia dulcis Thunb. had higher proportions of moisture (86.77 g/100 g) and carbohydrates (11.86 g/100 g). The mean values of the physicochemical analyses were as follows: pH 4.91, acidity 0.28, $^{\circ}Brix$ 12.63, reducing sugar 68.97, alcohol content 0.1, alcohol density 0.998. Moju made with 1% Hovenia dulcis Thunb. did not have effects on DPPH radical scavenging activity; however, superoxide dismutase activity was significantly higher than that of Moju made without Hovenia dulcis Thunb. For assessing physiological activities, 4-week-old male ICR mice were divided into six groups (n=10): normal control group (NC), ethanol-administered group (EC), EC plus low-dose Moju made with 0% Hovenia dulcis Thunb. (MCL), EC plus high-dose Moju made with 0% Hovenia dulcis Thunb. (MCH), EC plus low-dose Moju made with 1% Hovenia dulcis Thunb. (MDL), and EC plus high-dose Moju made with 1% Hovenia dulcis Thunb. (MDH). Serum triglyceride (TG) level was reduced by 11.17% and 19.61% in the MDL and MDH groups, respectively, compared to the EC group. Serum total-cholesterol levels of MDL and MDH groups were significantly lower as compared to the EC group. Serum high-density lipoprotein-cholesterol levels of the MDL and MDH groups were significantly higher than those of the EC group. Liver TG levels were significantly reduced in the MCL and MDL groups. From these results, Moju made with Hovenia dulcis Thunb. demonstrated antioxidant activity and reduction of hyperlipidemia markers. Therefore, Moju made with Hovenia dulcis Thunb. can serve as a non-alcoholic beverage and functional food source.