• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.125-131
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• 2018

The effect of 1-methylcyclopropene (1-MCP) in the storability of kimchi cabbage at cold storage condition was investigated. Kimchi cabbage (Brassica campestris L. cv Ryouckgwang) was divided four groups, forced air cooling (FAC), FAC + 0.03 mm linear low density polyethylene liner (Liner), $FAC+2{\mu}L{\cdot}L^{-1}$ 1-MCP (1-MCP), and FAC + 1-MCP + Liner. After each treatment kimchi cabbage was stored at $2^{\circ}C$, 95% RH. Quality parameters were weight loss, soluble solids content (SSC), firmness, and color ($CIE\;L^*$, $a^*$, $b^*$, chroma, hue angle). Weight loss during storage was showed significant difference by Liner treatment. In particular FAC + 1-MCP + Liner treatment showed 12.5% reduction after 6 weeks of storage period and minimized the weight loss rate compared to other treatments. SSC of kimchi cabbage was $2.5^{\circ}Brix$ at harvest and FAC + 1-MCP + Liner treatment maintained the SSC until 3 weeks, while in other treatments gradually were increased. The firmness of kimchi cabbage was 24.0 N immediately after harvest and the firmness at harvest time tended to be maintained at 22.6 N after 6 weeks of storage in FAC + 1-MCP + Liner treatment. During the storage period, the color change of the kimchi cabbage leaf can be confirmed by $CIE\;a^*$ and hue angle value. 1-MCP treatment alone did not affect the color change, however 1-MCP + Liner treatment was able to maintain the chromaticity at harvest time while minimizing the change of $CIE\;a^*$ and hue angle. These results suggest that 1-MCP treatment is not effective for the storage of kimchi cabbage but can be maintained for up to 6 weeks when treated with Liner.

• Journal of Bio-Environment Control
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• v.25 no.2
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• pp.89-94
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• 2016

This study was conducted to determine the optimum nutrient solution, pH, irrigation interval, light intensity and planting density to growth of common ice plant (Mesembryanthemum crystallinum L.) in a closed-type plant production system. Three-band radiation type fluorescent lamps with a 12-h photoperiod were used. Nutrient film technique systems with three layers were used for the plant growth system. Environmental conditions, such as air temperature, relative humidity and $CO_2$ concentration were controlled by an ON/OFF operation. Treatments were comparison of the nutrient solution of Horticultural Experiment Station in Japan (NHES) and the nutrient solution of Jeju National University (NJNU), pH 6.0 and 7.0, irrigation interval 5 min and 10 min, light intensity 90 and $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and within-row spacing 10 cm, 15 cm, 20 cm and 25 cm with between-row spacing 15 cm. Optimum macronutrients were composed N 7.65, P 0.65, K 4.0, Ca 1.6 and Mg $1.0mM{\cdot}L^{-1}$. There were no significant interactions between pH 6.0 and 7.0 about shoot fresh weight and shoot dry weight of common ice plant. Irrigation interval 5 min and 10 min was also the same result. Shoot fresh weight and shoot dry weight were highest at $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Shoot fresh weight and shoot dry weight were decreased according to increasing the planting density. From the above results, we concluded that optimum nutrient solution, optimum levels of pH, irrigation interval, light intensity and planting density were 6.0-7.0 and 10 min, $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and $15{\times}15cm$, respectively for growth of common ice plant in a closed-type plant production system.

• Journal of Bio-Environment Control
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• v.21 no.1
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• pp.1-11
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• 2012

The objective of the present study is to provide data needed to find double covering method to be able to improve environment of temperature, humidity and PPF in tomato greenhouse. The distribution charts of temperature, humidity and PPF which were measured in environment control conditions such as thermal insulation, air heating, roof ventilation and air fog cooling in conventional and air inflated double layers greenhouses were drawn and analysed. The thermal insulation effect of the air inflated greenhouse was the same as that of conventional greenhouse because the temperature between insulation curtain and roof covering material was equal in heating season. The ventilation effect of the air inflated greenhouse was superior to the conventional greenhouse. The temperature distribution in the fog cooled greenhouse was uniform and the cooling effect was about $3.5^{\circ}C$. The condensation on the roof covering surface could be controlled by removing the moisture between insulation curtain and roof covering by using humidifier. The PPF of conventional greenhouse was more decreased than the air inflated greenhouse as time went by because the transmittance of conventional greenhouse declined by dust collected on the inside plastic film owing to rolling up and down operation for ventilation.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.120-130
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• 1996

Crisphead lettuce(Lactuca sativa L.) was grown in NFT to investigate the effects of NO$_3$-N and NH$_4$-N ratio in nutrient solution and elevated $CO_2$ treatment in the crisphead lettuce growth. This experiment has been conducted under three different ratios of NO$_3$-N:NH$_4$-N(100:0, 75:25, 50:50) with two $CO_2$ concentration (control, 1500ppm ). The results are as follows; 1. In the case of not controlling pH and EC in nutrient solution, pH was gradually increased in NO$_3$-N:NH$_4$-N=100:0 treatment but rapidly decreased in the nutrient solution 2. Daily changes of NO$_3$-N and NH$_4$-N were observed without controlling the nutrient solution. In the treatments of NO$_3$-N:NH$_4$-N ratios were 75:25 and 50:50, NO$_3$-N absorption rates were 27.7% and 26.1%, while NH$_4$-N absorption rates were 87.9% and 71.2%, respectively. 3. There was little differences in total nitrogen of leaves. However phosphorus, potassium, calcium and magnesium contents were highly shown in the treatment of $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. 4. Higher $CO_2$ assimilation rate was shown in plants grown under $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. It dropped significantly with the increase of NH$_4$- N rates in nutrient solution. 5. Fresh weight, leaf number, root length and root weight of crisphead lettuce were far better in the treatment of $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. Growth differences by $CO_2$ elevation were not shown in other NO$_3$-N:NH$_4$-N treatments. 6. The highest nitrate contents of leaves were shown in NO$_3$-N single treatment but shown the lowest vitamin C contents. Nitrate contents of leaves were decreased by $CO_2$ but the effect was slight treatment.

• Journal of Bio-Environment Control
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• v.3 no.2
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• pp.106-118
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• 1994

This study was conducted to analyze the effects of fluctuations in temperature, light intensity and soil temperature on the growth of red pepper seedlings in the nonheated plastic houses with various number of layers and in the open field. Relationship between the optimal environment and the growth of seedlings was discussed, and the maximum and minimum outdoor temperatures in Kwangju area from 1941 to 1985 were analyzed. The results obtained were as follows; 1. The minimum temperature in tunnel with quadruple coverings of P. E. film from December 20 to February 25 was decreased to 5$^{\circ}C$ mostly, where the exposure to chilling temperature could not be avoided during this period. The maximum temperature was increased to 33$^{\circ}C$ mostly and 42$^{\circ}C$ in peak, where some ventilation was needed. 2. The diurnal differences of inside temperature, increasing with number of layers, were 16 to 38$^{\circ}C$, while those of outside temperature were 5 to 1$0^{\circ}C$. 3. The cold injury in the quadruple coverings during winter occurred all the times below 12$^{\circ}C$ and as many as 200 times over 3$0^{\circ}C$, while effectiveness of thermal insulation in the multilayered nonheating plastic houses were clearly proved. 4. The inside light intensity was markedly reduced with the increment of layers and the minimum light intensity fallen down below the light compensation point for the growth of red pepper plants regardless of the number of layers. 5. Until 10 a. m., the temperature in the daytime during December 20 to mid - February showed below 10 to 12$^{\circ}C$ which was the limiting temperature for the growth of red pepper seedlings. After 4 p. m., the light intensity was sharply reduced despite of the air temperature kept over 12$^{\circ}C$. Therefore, limiting factors for the growth of red pepper seedlings were the temperature before 10 a. m. and the light intensity after 4 p. m. 6. The minimum soil temperature in quadruple coverings showed around 1$0^{\circ}C$ where the physiological damage for red pepper seedlings might be occurred. 7. The minimum outdoor temperatures from 1941 to 1985 was -19.4$^{\circ}C$, observed in the 5th January.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.376-382
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• 2014

This work was conducted to investigate the variation of growth and yield among three generations ($TC_0$, $TC_1$, and $TC_2$) in the field cultivation of virus-free sweetpotato (Ipomoea batatas) plants. Virus-free generations of three cultivars ('Matnami', 'Shinhwangmi', and 'Yeonhwangmi') were cultivated with $75{\times}25cm$ planting density on May 20th, covered with black vinyl film. At 30 days after planting, vine growth in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant, and vine length in $TC_0$ showed the highest growth among treatments. At harvesting time after 120 days, vine diameter, number of node, and number of branch in $TC_0$, $TC_1$, and $TC_2$ were more increased than farmer's plant, but were not statistically significant. Fresh weight of shoot in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant, but was not statistically significant among generations or cultivars. Number of tuber per plant and mean weight of tuber in $TC_0$ and $TC_1$ showed significant increasement, but that in $TC_2$ did not show significant difference as compared to the farmer's plant. Weight of tuber per plant in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant. Marketable yield, percentage of marketable tuber, and percentage of small tuber (40 to 200g) in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant. The large tuber over 300g showed the lowest percentage in $TC_0$. Marketable yield in $TC_2$ was significantly decreased as compared to $TC_0$, and was not significantly different as compared to the farmer's plant. Marketable yield in 'Matnami' was highest among cultivars. From this results, Farmers are required to renew every three years to maintain the yield and quality of virus-free plants. However, the exchange period of virus-free plants is desirable to renew every 2 or 3 years according to the degree of virus reinfection.

• Journal of Bio-Environment Control
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• v.24 no.4
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• pp.281-286
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• 2015

This study was carried out to investigate the effects of cultural systems on growth, vitamin C, amino acid content, and yield of Peucedanum japonicum grown in artificial light plant factory. Treatments were given with Nutrient Film Technique (NFT), Medium (Perlite), and Aeroponics. Plant height was the highest in NFT system as 10.2cm, and was the shortest in Perlite as 8.9cm. Fresh leaf weight was the high in order of Perlite, NFT, and Aeroponics. Total phenolic compounds was different from cultural systems in order of Aeroponics as $117.84mg{\cdot}100g^{-1}\;GE$, NFT as $98.57mg{\cdot}100g^{-1}\;GE$ and Perlite as $74.62mg{\cdot}100g^{-1}\;GE$. Total flavonoid content of Aeroponics is $0.12mg{\cdot}100g^{-1}$ but that of NFT and Perlite treatments is not detected. Vitamin C content in Aeroponics as $108.23mg{\cdot}100g^{-1}$ was significant different from Perlite as $88.05mg{\cdot}100g^{-1}$ as and NFT $80.83mg{\cdot}100g^{-1}$. Total dietary fiber content was higher Aeroponics than Perlite and NFT. Cystein content was the highest in Aeroponics as $46.76mg{\cdot}100g^{-1}$ and methione content was the lowest in Perlite as $75.64mg{\cdot}100g^{-1}$. Mineral content of leaves was high in order of K, Ca, P and Mg in all treatments.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.360-365
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• 2010

The effects of precooling treatments on the storability of chicon were investigated during modified atmosphere (MA) storage. The forced air cooling showed faster precooling rate that reduced the internal temperature of chicon to $2{\pm}1^{\circ}C$, and the precooling time of forced air cooling was 1/6 of room cooling. The half cooling time was 3 hr 21 min in room cooling and 1 hr 17 min in forced air cooling. Weight loss was less than 0.5% in all treatments both $5^{\circ}C$ and $10^{\circ}C$ MA storage and maintained higher in forced air cooling treatment. The concentration of carbon dioxide, oxygen, and ethylene of $50{\mu}m$ ceramic film packages were observed higher at $10^{\circ}C$ than $5^{\circ}C$. The precooling effect on respiration reduction was not shown at $5^{\circ}C$, but appeared that the gas concentration of precooling treatments showed less carbon dioxide and higher oxygen than non precooling treatment by 9 days after $10^{\circ}C$ storage. Ethylene concentration of precooling treatments showed lower than non precooling treatment until 3 days both $5^{\circ}C$ and $10^{\circ}C$ MA storage. Precooling showed the effect on maintaining visual quality of chicon both $5^{\circ}C$ and $10^{\circ}C$ MA storage. However, the forced air cooling that showed faster precooling rate did not appeared more precooling effect on the visual quality than room cooling because the fast air flow (6.0 m/sec) of forced air cooling hit directly on chicon outer leaves and might cause physical damage to chicon. Although the forced air cooling showed the effect on maintaining quality of chicon, but additional studies should be needed that investigated proper air flow rate and cooling box structure can prevent physical damage by air flow.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.291-296
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• 2009

This study was conducted to compare the storability of 6 chicory cultivars for producing chicon; 'Vintor', 'Focus', 'Metafora', 'Kibora', 'Nobus', and 'Redoria Red' grown in 2 regions: Chuncheon (plain region) and Pyeongchang (high land region). Chicons were produced from chicory roots that grown for 120days and then stored for over 120days at $2^{\circ}C$ and 90% of RH conditions. To produce chicon, chicory root was forced at $18^{\circ}C$ for 22days with suppling the nutrient solution ($KNO_30.54g{\cdot}L^{-1}$, $Ca(NO_3)_2\;1.02g{\cdot}L^{-1}$, $MgSO_4\;0.36g{\cdot}L^{-1}$, $KH_2PO_4\;0.21g{\cdot}L^{-1}$, $K_2SO_4\;0.10g{\cdot}L^{-1}$, pH 7.0). Chicons produced from 6 different chicory cultivars packed with $25{\mu}m$ ceramic film and stored for 25days at $8^{\circ}C$. The fresh weight of chicon in MAP was maintained to 99.5% of pre-storage weight. The fresh weight of 'Redoria Red' was lowest in all cultivars, and that of Chuncheon region cultivated treatment was lower than Pyeongchang treatment. The $CO_2$ and $O_2$ concentration in chicon MAP were 2% and $10{\sim}17%$. There were not significantly different among cultivars and between regions, although 'Redoria Red' cultivar showed highest $CO_2$ and lowest $O_2$ concentrations. The ethylene concentration in chicon MAP was $1.0{\mu}{\iota}{\cdot}{\iota}^{-1}$ and also didn't show any significant difference among all treatments. Chicon detoriorated visual quality with appearing russet spotting that result from ethylene gas. The visual quality of 'Redoria Red' cultivar decreased faster than the other cultivars. 'Metafora', 'Focus', and 'Kibora' maintained higher firmness of their leaf than the others, and the firmness was higher grown in Pyeongchang region cultivated treatments than in Chuncheon region.

• Journal of Bio-Environment Control
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• v.23 no.2
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• pp.109-115
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• 2014

This study examined the uplift bearing capacity of spiral steel pegs according to the degree of soil compaction and embedded depth in a small-scaled lab test. As a result, their uplift bearing capacity increased according to the degree of soil compaction and embedded depth. The uplift bearing capacity under the ground condition of 85% compaction rate especially recorded 48.9 kgf, 57.9 kgf, 86.2 kgf and 116.6 kgf at embedded depth of 25 cm, 30 cm, 35 cm and 40 cm, respectively, being considerably higher than under other ground conditions. There were huge differences in the uplift bearing capacity of spiral steel pegs according to the compaction conditions of ground. Their maximum uplift bearing capacity was 116.6 kgf under the ground condition of 85% compaction rate and at embedded depth of 40 cm, and it is very high considering the data of spiral steel pegs. It is thus estimated that wind damage can be effectively reduced by careful maintenance of ground condition surrounding spiral steel pegs. In addition, spiral steel pegs will be able to make a contribution to greenhouse structural stability if proper installation methods are provided including the number and interval according to the types of greenhouse as well as fixation of plastic film. The findings of the study indicate that the optimal effects of spiral steel pegs for greenhouse can be achieved at embedded depth of more than 35cm and compaction degree of more than 85%. The relative density of the model ground in the test was 67% at compaction rate of 85%.