• Journal of Bio-Environment Control
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• v.14 no.3
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• pp.155-159
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• 2005

This study was carried out to investigate the effects of cultivars and to establish the hydroponic cultivation method of spinach (Spinacia oleracea L.) f3r autumn season. Considering the rate of germination, plant height is 25 cm interior and exterior and leaf blade and petiole attitude is erect the best two cultivars 'Artlars', 'Dimple' were selected among the 19 cultivars tested. Seed germination was more than $90{\%}$ in both cultivars of 'Artlars', 'Dimple'. Seed rate of germination drops more or less, but it was cultivar that 'Mahoroba' cultivars is becoming in export standard production, and 'Premium', 'Platon' cultivar which plant height of leaf blade and petiole attitude is erect is about 20 cm was thought by suitable cultivars to domestic. Plant height relationship difference that follow to planting distances decreased according as planting distances growth than $12{\times}11$ cm to $12{\times}15$ cm. In the meantime, the increase of leaf area and fresh weight was increasing transplanting distance. The yield per ha of 14,890 kg in the $12{\times}11$ cm was $67{\%}$ increased than that in the $12{\times}9$ cm. Therefore, $12{\times}11$ cm spacing is considered optimum planting distance for spinach hydroponic cultivation in autumn season.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.181-185
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• 1998

Gain characteristic of concatenated erbium-doped fiber amplifiers(EDFA) are studied with a recirculating EDFA loop. For a non-flat gain EDFA, the 3 dB gain bandwidth was reduced to 6 nm after the 20th EDFA. However, for an optimized gain flattened EDFA, in a simple configuration, the 5 dB gain bandwidth was found to be 9nm, even after the 100th EDFA, corresponding to 8000km transmission. This results suggest that the simple optimized flat gain amplifier could be a good candidate for ultra-long distance wavelength division multiplexed transmissions.

• Korean Journal of Optics and Photonics
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• v.9 no.6
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• pp.413-416
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• 1998

We have flattened the gain of EDFA by using a long-period FBG filter and AOTF's. The gain and optical SNR characteristics of the gain-flattened EDFA in long-haul transmission been evaluated in a recirculating EDFA loop. The gain variation was less than 4.6 dB and the optical SNR was higher than 14 dB over 20-nm wavelength range when the optical signal went through the EDFA as many as 200 times. These results indicate that this gain-flattened EDFA is applicable for ultra long-haul WDM optical transmissions over 8000 km.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.1
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• pp.1-4
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• 1988

This study was invesigated to find out the optimum planting densities of Sculellaria baicalensis GEORGE about growth characters, yield components and yield at 6 planting densities by direct sowing culture. The results obtained are summarized as follows ; Studying the correlationship, the highly negative significances were found between planting densities and dry wights of root, leaves and stem ; on the other hand, the highly positive significances were found between planting densities and plant hight, stem diameter, respeitively. Plant height was long in dense planting, and short in spacious planting by direct sowing culture. Stem diameter was thick in spacious planting, and was thin in dense planting. Length and dry weight of root per plant were decreased in dense planting and were increased in spacious planting by direct sowing culture. Quality and yield of dry root weight were highest in optimum planting densities (30${\times}$10cm ; 33plants/m$^2$) by direct sowing culture.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.433-438
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• 2013

Interference reduction method of vehicle collision avoidance sensor which is used for the low speed electric vehicle has been investigated. Various methods were attempted for the vehicle collision avoidance distance sensor, which received a transmitted signal from a front driving vehicle to measure the distance between two vehicles, to avoid interference by the own transmitter signal toward the rear following vehicle. In this study, -12dB of interference cancellation ratio was realized by using the phase cancellation method to the transmitted signal from the own vehicle. Proposed phase cancellation method is regarded to have the advantage of continuous monitoring in comparison to the conventional time sharing transmitting and receiving method.

• Korean Journal of Organic Agriculture
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• v.24 no.1
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• pp.99-114
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• 2016

This study was conducted to evaluate effects of various eco light sources with various lighting distance in 'Viking' rose (Rosa spp.) on the growth and flowering quality to be applied for farm sites. Treatment included 10-, 20-, and 30-RL (-BL, -RBL, -FL, and -IL), which referred to red LED (blue LED, red+blue LED, fluorescent, and incandescent) lighting at 10 cm, 20 cm, 30 cm respectively, apart from flowers. NL referred to natural light as a control. Growth and flowering of 'Viking' rose were non-destructively measured at 4, 6, and 8 weeks after treatment (WAT). FL treatment increased plant height at 4, 6, and 8 WAT, regardless of lighting distance, with the shortest height observed for the NL-treated flowers. 30 RL treatment also increased plant height at 6 and 8 WAT. Stem diameter and number of leaves were not significantly different for all the treatments at 8 WAT, with the lowest values observed for RBL treated-flowers among the light source treatments. Number of root was the greatest for the 30 BL-treated flowers (10.0) but the fewest for the 30 FL (4.7). Length of flower neck at 6 WAT was the extended by 6~7 cm in the 10 FL and 20 FL treatments as well as by 5~6 cm in the 20 RL and 30 RL treatments, inducing 100% of flowering. NL increased $a^*$ (29) of flower color, with the lowest value (10) observed for 20 RL. All things considered, 30 RL would be the best interaction treatment of source and distance of eco light to improve plant height and flowering quality of 'Viking' rose.

• FLOWER RESEARCH JOURNAL
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• v.17 no.3
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• pp.147-151
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• 2009

The research was carried out a solution to prevent the breakage of stem resulted from stem cavity in the Dendranthema grandiflorum Ramat. 'Baekma'. Stem cavity occurred in the lower parts of stem for about 5 cm long as the stem grew to 20 cm, and the breakage increased to about 60 cm as the stem grew to 80 cm. Plant height, stem diameter, and flower stalk length were the highest in the planting density of $11cm{\times}11cm$. The light interception by plants increased as the planting density decreased (47, 99 and 143%). The strength and hardness values were the greatest, $567kg{\cdot}cm^{-2}$ and $1,339kg{\cdot}cm^{-2}$ in the planting density of $11cm{\times}11cm$. Plant height and plant weight increased in the foliage fertilization of one time, but the plants in the control flowered earlier. The strength and hardness increased in the foliage fertilization treatments and the greatest in the treatment of one time application of $60mg{\cdot}L^{-1}$ Silicate fertilization. The Si content of stems increased as the fertilization concentration and treatment time increased. The Si content in $30mg{\cdot}L^{-1}$ silicate treated twice was two times as high as that of the control.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.4
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• pp.355-360
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• 1992

The experiment was carried out to study the influence of planting densities and fertilizer application levels on some agronomic characters and yield of flower-head in Zingiber mioga ROSC. The results obtained are summarized as follows ; Plant hight was long in dense planting, and short in spacious planting. Stem diameter was thick in spacious planting, and was thin in dense planting. Flower-head weight per plant was decreased in dense planting and was increased in spacious planting. Yield was higher in dense planting densities (10$\times$20 : 50plants /m$^2$, 20$\times$20 : 25plant /m$^2$). Fertilizing (N : P$_2$O$_{5}$ : $K_2$O=15 : 15 : 15kg /10a) was increased than without fertilizing because plant height and number of stem was good.d.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.4
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• pp.340-344
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• 1991

This study was investigated to find out the optimum planting densities fo Solanum njrum L. about growth characters. yield components and yield at 6 planting densities by direct sowing culture. The results obtained are summarized as follows: Studying the correlationship. the highly negative significances were found between planting densities and fresh eights weights per plant, on the other hand, the highly positive significances were found between planting densities and plant height. Plant height was long in dense planting, and short in spacious planting by direct sowing culture. Stem diameter was thick in spacious planting. and was thin in dense planting. Fresh wt. per plant was decreased in dense planting and was increased in spacious planting by direct sowing culture. Yield was highest in dense planting densities (10 x 20cm : 50plants/$m^2$) by direct sowing culture. Fertilizing ((N： P$_2$O$_{5}$ $K_2$O=6 : 6 : 6Kg/10a) was increased than without fertilizing because plant height and number of branch was good.d.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.580-584
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• 2010

The effect of planting densities on the growth of $Sedum$ $samentosum$ (4 collections) was investigated using nutrient film technique (NFT) with Yamazaki' lettuce nutrient solution (1982) from September 5th to October 24th in non-heating plastic film house. At 40 days, the plant height of 4 collections showed the range of 15.0-18.9 cm, and mean plant height was high the order of $10{\times}10$, $2.5{\times}2.5$, and $5{\times}5cm$. The growth of 'Pohang' and 'Wando' collections was better compared to that of 'Gunsan' and 'Wanju' collections. Number of node, stem diameter, and fresh and dry weight per plant were decreased in higher planting density. Despite the lower fresh weight per plant obtained, the fresh yield per $m^2$ was significantly increased in higher planting density. The mean fresh yield was $14.9kg{\cdot}m^{-2}$ in $2.5{\times}2.5cm$, and 'Pohang' collection showed the highest fresh yield ($17.6kg{\cdot}m^{-2}$). The first optimized harvesting time base on plant height was 30-40 days after NFT culture during autumn season. In eating quality, compression force of stem and bitterness of shoot were decreased in higher planting density. However, the heavy labor demanding high density cutting needs to be improved for hydroponic culture of $S.$ $samentosum$.