• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.717-721
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• 2011

In case of plastic film greenhouses cultivating fresh vegetables on paddy soil, soil characteristics must be considered as more important factor than any other factors. Generally after the four years of cultivation, soils tend to increase electrical conductivity value, nutrient unbalance and soil pests. As a result, degradation of agricultural products occurred, therefore it is necessary to improve soil conditions. In this study, yield and economic cost of cucumber were analyzed. The best soil conditions for cucumber cultivation were alluvial or valley in soil topology, moderately or poorly drainage in soil drainage classes, coarse loamy soil in texture. In addition, rich-sunlight and-deep groundwater would be proper for the cucumber cultivation. Good environmental managements of plastic film greenhouse were as follows. The temperature needed to be adjusted three times. The optimal daytime temperature could be $22{\sim}28^{\circ}C$, the one from 12 until night could be $14{\sim}15^{\circ}C$, and the temperature from 24 to sunrise could be $10{\sim}12^{\circ}C$. During plant growth period, soil moisture content was as low as 10~15%, and it needed to be maintained as 15~20% during reproductive growth period. To control pests, catch crop cultivation and solar treatment were carried out, after those EC was reduced and the root-knot nematode was controled too. Cucumber yield from the plot with improved soil managements increased to $158.4Mg\;ha^{-1}$, but plot with successive cropping injury yielded $140.3Mg\;ha^{-1}$. The income from the plot with improved soil managements was 215,676 thousand won $ha^{-1}$, the plot with successive cropping injury was 131,649 thousand won $ha^{-1}$. Income rate of each plot was 51.8% and 38.4%, respectively.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.356-365
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• 2022

Agrivoltaic systems, also called solar sharing, stated from an idea that utilizes sunlight above the light saturation point of crops for power generation using solar panels. The agrivoltaic systems are expected to reduce the incident solar radiation, the consequent surface cooling effect, and evapotranspiration, and bring additional income to farms through solar power generation by combining crops with solar photovoltaics. In this study, to evaluate if agrivoltaic systems are suitable for viticulture, we investigated the microclimatic change, the growth of vines and the characteristics of grape grown under solar panels set by planting lines compared with ones in open vineyards. There was high reduction of wind speed during over-wintering season, and low soil temperature under solar panel compared to those in the open field. There was not significant difference in total carbohydrates and bud burst in bearing mother branches between plots. Despite high content of chlorophyll in vines grown under panels, there is no significant difference in shoot growth of vines, berry weight, cluster weight, total soluble solid content and acidity of berries, and anthocyanin content of berry skins in harvested grapes in vineyards under panels and open vineyards. It was observed that harvesting season was delayed by 7-10 days due to late skin coloration in grapes grown in vineyards under panels compared to ones grown in open vineyards. The results from this study would be used as data required in development of viticulture system under panel in the future and further study for evaluating the influence of agrivoltaic system on production of crops including grapes.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.285-286
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• 2012

육각형 구조를 지닌 2차원의 물질인 그래핀은 우수한 전도도와 투과율로 투명전극의 신소재로 각광 받고 있다. 특히, 그래핀은 현재 투명전극으로 가장 많이 사용되고 있는 Indium Tin Oxide(ITO)로는 구현하기 힘든 Flexible display의 어플리케이션으로 사용하기 위한 목적으로 많은 기술 개발이 이루어지고 있다. 이러한 그래핀의 응용은 가장 먼저 그래핀의 생산이 안정적이고 원활히 이루어질 때 실질적으로 가능할 것이다. 하지만, 탄소로 이루어진 그래핀의 성장은 제한된 기판 위에서만 가능하기 때문에 성장이 이루어진 그래핀을 다른 기판에 전사시켜야하는 문제점이 있다. 그래핀 전사방법에는 직접전사, PMMA 전사, TRT 전사, 금속전사, 망전사, PDMS 전사 등 다양한 방법이 있다. 이 중에서 현재 가장 많이 사용되고 있는 전사방법으로는 직접전사, PMMA 전사, TRT 전사 방법이 있다. 직접전사의 경우 니켈위에 성장된 다층의 그래핀을 전사시킬 때 많이 사용되는 방법으로 니켈 에천트에 전사 시킬 그래핀을 띄워 니켈을 녹인 후 원하는 기판을 이용하여 전사하는 간단한 방법이다. 직접전사는 전사가 이루어진 후 그래핀에 남는 결함이 거의 존재 하지 않는 장점이 있지만 문제점은 단일층의 그래핀의 경우 니켈 에천트위에서 잘 보이지 않을 뿐 아니라 에천트에서 기판으로 전사할 때 너무 얇은 막으로 인해 다 찢어져버린다는 것이다. 이를 해결하기 위해 사용되는 전사 방법으로 TRT를 이용하여 구리위에 성장된 그래핀을 상온 시에는 점성을 가진 테이프를 이용해 부치고 구리에 천트에 구리를 녹인 후 원하는 기판위에 놓고 열을 가해 그래핀을 전사하는 방법이 있다. TRT 전사방법은 얇은 막의 그래핀을 찢어지지 않도록 지지해주어 대면적 기판위에도 전사 할 수 있는 장점이 있지만 전사 후 그래핀에 남아 있는 잔여물들이 많고(그림 1. (b)), 테이프를 이용한다는 점에서 그래핀의 얇은 막이 손상될 수 있는 단점이 있다. 그렇기 때문에 본 연구에서는 직접전사와 TRT전사의 문제점들인 전사 후 잔여물와 그래핀 단일층의 손상을 최소화할 수 있는 방법으로 PMMA전사를 가장 적합한 전사방법이라는 것을 라만 분석, 면 저항측정, 그래핀을 이용한 LED제작을 통해서 살펴 보았다. 먼저 라만 분석을 이용해 TRT전사 후 상당히 많은 빈 공간이 생김을 확인할 수 있었으며, 결과적으로 면 저항이 약 $1.5k{\Omega}$~$3M{\Omega}$까지 PMMA의 약 0.9~1.2 $k{\Omega}$와 비교했을 때 큰 차이가 있음을 확인할 수 있었다. 또한, 이후 각각의 전사방법으로 얻은 그래핀을 LED의 스프레딩 층으로 제작한 결과에서도 TRT전사방법보다 PMMA전사방법의 결과가 좋음을 알 수 있었다(그림 2).

• Clean Technology
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• v.19 no.2
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• pp.156-164
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• 2013

In this study, we analyzed the operational characteristics of a 0.25 MW methanation pilot plant. Isothermal reactor controled the heat released from methanation reaction by saturated water in shell side. Methanation process consisting of isothermal reactor and adiabatic reactor had advantages with no recycle compressor and more less reactors compared with methanation process with only adiabatic reactors. In case that $H_2$/CO ratio of syngas was under 3, carbon deposition occurred on catalyst in tube side of isothermal reactor and the pressure of reactors increased. In case that $H_2$/CO ratio was maintained around 3, no carbon deposition on catalyst in tube side of isothermal reactor was found by monitoring the differential pressure of reactors and by measuring the differential pressure of several of tubes filled with catalyst before and after operating. It was shown that CO conversion and $CH_4$selectivity were over 99, 97%, respectively, and the maximum $CH_4$productivity was $695ml/h{\cdot}g-cat$.

• Journal of the Korea Institute of Building Construction
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• v.15 no.1
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• pp.43-51
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• 2015

At present, in the case of small and medium window manufacturers in South Korea, glazing and window frame manufacturers are divided into separate businesses. However, in the fenestration energy consumption efficiency rating system and the energy-saving design criteria for buildings, the coefficient of overall heat transmission standard for windows is defined by window sets, which integrate glazing and window frames. At most construction sites, windows are constructed by installing separately supplied glass and frames. Research that can integrate the reality and the system is therefore necessary. The present study first investigated and analyzed the on-site situation of the fenestration energy consumption efficiency rating system. According to the results, while overall understanding of the fenestration energy consumption efficiency rating system was high, satisfaction with it was low, and the general practice at construction sites was to use windows assembled on site rather than integrated window systems manufactured at factories, thus making it difficult to confirm that the current rating system was well applied on site. Consequently, the reality of industrial sites must be reviewed and a realistic alternative to the fenestration energy consumption efficiency rating system must be presented instead of focusing on theory.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.4
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• pp.309-316
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• 1999

This Study was carried out to compare growth characteristics and yield of 10 cultivated soybean varieties, Jinpum I, Jinpum II, Hwanggum, Gumjung I, Gumjung II, Seukryangboot, Jangyup, Gumjungol, Bokwang, Manri for improvement of soiling crop. Plant height of Gumjung I(118cm), Gumjung II(114cm) and Jinpum I(114cm) were taller than other varieties based on dough stage. In total fresh weight and DM yield of Jinpum I, Jinpum II, Gumjung II were the highest of all varieties as 23,841kg, 23,499kg and 22,815kg per hectare, and 5,531kg, 5,173kg and 5,236kg per hectare, respectively. The highest leaf/stem ratio of ten soybean varieties were Manri(2.1), Jinpum I(1.9) and Hwanggum(1.9). Except early matured varieties, Seukryangboot(25.9%) and Gumjungol(25.4%), dry matter percent at dough stage were in the range of 22.0~23.4%. According to plant height, fresh weight, dry matter yield, and leaf/stem ratio, Jinpum I and Gumjung II were proper varieties to improve soiling crop.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.165-170
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• 2014

The objective of this study was to make growth and yield models of sowthistle (Ixeris dentata Nakai) by using an expolinear functional equation in a closed-type plant production system. The growth and yield of hydroponically-grown sowthistle were investigated under four different planting distances ($15{\times}10$, $15{\times}15$, $15{\times}20$, and $15{\times}25$ cm). Shoot dry weights per plant was the highest at $15{\times}25$ cm, but was the lowest at $15{\times}10$ cm. Shoot dry weights per area was the highest at $15{\times}15$ cm, but was the lowest at $15{\times}25$ cm. The optimum planting density and planting distance for yield of sowthistle were 44 plants/$m^2$ and $15{\times}15$ cm, respectively. Shoot dry weights per plant and per area were showed as an expolinear type functional equation. A linear relationship between shoot dry and fresh weights was observed to be linear regardless of the planting distance. Crop growth rate, relative growth rate and lost time in an expolinear functional equation showed quadratic function form. Radiation use efficiency of sowthistle was $4.3-6.1g{\cdot}MJ^{-1}$. The measured and estimated shoot dry weights showed a good agreement using days after transplanting as input data. It is concluded that the expolinear growth model can be a useful tool for quantifying the growth and yield of sowthistle in a closed-type plant production system.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.2
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• pp.49-57
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• 2020

Due to the sewage sludge's characteristics of high water content and low calorific value, it is hard to use sewage sludge as an energy source. In this study, we investigated production of bio-solid fuel which is mixed both sewage sludge and woody biomass in order to improve the sewage sludge's characteristics and replace fossil fuels. A thermogravimetric analysis was used to investigate the co-combustion characteristics of the mixed coal and bio-solid fuel of 5%, 10%, 15%, respectively. The analysis was carried out under non-isothermal conditions by raising the internal temperature of 25℃ to 900℃ with an increment of 10℃/min. In the case of comparing single coal sample and mixture sample of coal and bio-solid fuel, the initiation combustion temperature has slightly changed. However, both the maximum combustion temperature and the termination start combustion temperature were hardly noticeable. The initiation combustion was occurred between 200~315℃ and the thermal decomposition causing a significant weight change occurred between 350~700℃. As a result of the kinetic analysis of the co-combustion, the activation energy was decreased as the mixing rate was higher. Therefore, it is able to co-combust the mixed coal and bio-solid fuel in power plants.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.3
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• pp.145-151
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• 2009

This study was conducted to develop rational soil management and enhance the productivity of lands converted from paddy soils. Specifically, the changes in the soil physical properties brought about by the change in land usage from paddy soil were evaluated. This was carried out from 1999 to 2001 at 50 site in large-scale converted paddy fields of Kimcheon, Youngcheon, Gyeongsan and Milyang in the Youngnam region, categorized according to soil texture and drainage class. The ridge height of converted paddy soils was higher in coarse-textured and poorly-drained soils than in fine-textured and well-drained soils. The gray color of the surface soil was of lesser degree in converted soils than paddy soils and more notable in welldrained soils. The porosity ratio and the formation of aggregate structure were higher, and the appearance of soil mottling was deeper in converted paddy fields than in paddy soils. The glaying layer "g" of surface soil degraded with time. The porosity and amount of water stable aggregate was found to increase with time after conversion. The penetration resistance of the converted paddy soil was lower and deeper with time after conversion. The soil aeration of the converted paddy soil was lower in sandy loam than in loamy soil. Furthermore, soil aeration was influenced by ridge height and drainage class in poorly-drained soils.

• Journal of Mushroom
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• v.2 no.2
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• pp.69-75
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• 2004

This study was carried out to investigate effect of $CaCO_3$ treatment on cultivation of oyster mushroom for suppression of green mold disease and for promotion of mycelial growth to stabilize mushroom production in field and laboratory experiment. Treatment of $CaCO_3$ in PDA media promoted mycelial growth of mushroom and suppressed that of green mold. Addition of $CaCO_3$ in rice straw substrate increased mushroom mycelial growth compared with control. In that case, growth of green mold increased up to treated 0.6% $CaCO_3$ but decreased in treatment beyond 0.8% $CaCO_3$. There were some differences on effect of $CaCO_3$ treatment according to green mold species. Trichoderma longibrachiatum was effected but T. virens was not effected by treated $CaCO_3$. Differences among mushroom strains by treated $CaCO_3$ were not shown. It is confirmed that treatment of $CaCO_3$ can promote mushroom mycelial growth but it's not clear in the field. In the result of field test, treatment of $CaCO_3$ in rice straw substrates tended to increase yield and decrease incidence of disease compared with non-treatment. These results suggest that $CaCO_3$ treatment on cultivation of oyster mushroom can be applied to take preventive steps against of green mold disease.