• Environmental and Resource Economics Review
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• v.15 no.2
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• pp.297-318
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• 2006

Imported natural gas has been consumed by urban gas use and generation sector in Korea. The share of generating sector in total demand for natural gas is only 33% at 2000. This paper examines the potential of natural gas use in generation sector in the future. We build some hypothetical but realistic scenarios reflecting rapidly changing economic environment. We used standard programs for plant mix decision under those scenarios. We found that it is very likely to have high gas demand in the future, if we remove the cross-subsidizing price structure.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.67-67
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• 2018

차요테(Sechium edule L.)는 중앙아메리카와 멕시코 남부가 원산인 박과 채소로 찜, 볶음, 튀김, 수프, 샐러드로 활용되는 아열대 채소다. 어린 순은 양념으로 무치거나 볶아서 나물로 이용되고, 열매는 샐러드, 수프, 볶음, 절임 등으로 이용된다. 동양에서는 뿌리채소로 이용되는 무(Raphanus sativus L.)와 유사하게 활용되고 있기도 하며, 인도네시아에서는 칠리 소스, 기름 등에 볶아 먹거나, 삶아서 양념을 찍어 먹기도 한다. 영양학적으로 열매에는 엽산, 비타민 C, 비타민 B6, 구리(Cu), 마그네슘(Mg) 등 미네랄이 풍부하며, 특히 칼륨(K)이 많이 함유되어 있다. 생태적으로 아열대지역에서는 다년생이지만 우리 나라에서는 일년생으로 취급하여, 봄에 정식하여 가을철에 개화되며, 늦가을에서 초겨울까지 열매를 수확한다. 본 연구는 중부지방에서 차요테 열매의 수확량이 줄어들지 않으면서, 차요테의 어린 순을 수확할 수 있는 재배기술을 개발하기 위하여, 2017년에 이어 2018년에도 동일한 처리로 시험을 수행하였다. 시설하우스에서 $2{\times}3m$ 간격으로 2018년 2월 9일부터 4월 21일까지 15일 간격으로 6회 파종하였고, 처리별로 발아시, 발아기, 발아전, 초장, 엽수, 엽록소함량, 어린순 수확량 등을 조사했다. 4차 처리구인 3월 23일 파종의 경우 발아시(최초 발아일)는 파종 후 4일이 소요되어, 1차 처리구 2월 10일 파종 보다 18일 빨랐고, 발아기(40% 발아)는 파종 후 10일로 24일 빨랐으며, 발아전(80% 발아)은 파종 후 16일로 25일 정도 더 빨리 발아되는 경향이었다. 정식 후부터 6월 하순까지 어린순 생산량은 4차 파종 시 773 g주$^{-1}$로 1차 파종 785g주$^{-1}$와 차이가 없을 정도로 생육이 좋았지만, 5차 파종 및 6차 파종의 경우 생산량이 저조하였다. 따라서, 하반기 과실 생산량을 추가적으로 조사하고, 어린순 생산량과 비교하여 중부지역 차요테의 최적 파종시기를 정할 수 있을 것으로 판단되었다.

• Resources Recycling
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• v.14 no.1
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• pp.26-32
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• 2005

A study on the preparation of Ag fine particles was performed through a reduction reaction using ascorbic acids as a reductant, which is one of the indispensable processes for the recycling of silver-bearing wastes. Silver nitrate solution in the range of 10~120 mmole/l was used and Tamol NN8906 or PVP was also used as a dispersant in the preparation of Ag fine particles size analyze, SEM, and TEM to determine the particle size and morphology of them. As a result, the reduction reaction of silver ions with ascorbic acid reached equilibrium within 10 min. It was found that about 60% excess of ascorbic acid was required in order to reduce completely silver ions in the solution. The particle size distribution of Ag particles prepared through the reduction reaction showed typically biomodal or trimodal distribution. Especially, initial Ag concentration in the solution, the type and amount of dispersant added during the reduction reaction played an important role in determining the mean particle size of Ag particles.

• Korean Journal of Plant Resources
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• v.14 no.2
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• pp.94-101
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• 2001

This study was intended to evaluate the relationship environmental condition and growth characteristics of seed treatment seed in direct sowing with different sowing date, and to suggest new cultivation model. The emergence percentage and hours were down as the delayed sowing date. Optimum sowing time was Sep. 10, and sowing must end before Sep. 20 for safety yield. When did sowing ended before Sep.20 in direct sowing cultivation, the seedling growth(SG) and No of roots of direct sowing seedling were larger than transplanting cultivation . At March 8 evaluated seedling, the SG of direct sowing seedling was higher than transplanting, and at Sep. 2(1 those were similar. The missing plant rate in transplanting cultivation was under 3 %, and that in direct sowing cultivation was about 13∼18%, and the extent were sever as delayed sowing date. The bulb fresh weight was decreased as delayed sowing, and those in direct sowing and transplanting cultivation were 230, 217g, respectively. The blot rate was high in direct sowing cultivation, and that was decreased as delayed sowing. The yield in direct sowing and transplanting cultivation were 5,134, 5,300kg, respectively, and those were decreased as delayed sowing. The average yield in early and medium-late maturity cultivars were 3,750, 4,908kg, respectively, and Sonic was highest yield in early maturity cultivars and Nongwoodego was highest in medium-late maturity cultivars. The emergence weed were 9 species as Loportea bulbifera Weddell and others, and Loported bulbifera Weddell, Digitaria violascens Link and Persicaria longiseta Kitagawa were dominant species in direct sowing cultivation with black hole vinyl mulching

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.4
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• pp.705-716
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• 2017

As many environmental pollution problems have arisen, various studies related to the environmental evaluation have been carried out in the construction industry. However, there is no methodology for estimating the environmental load quickly for design alternatives of civil facilities in the design phase. This study aim to establish criteria of works information and designed parts which can efficiently estimate environmental loads of PSC beam bridge based on standard quantity at the early design phase. For this purpose, a detailed environmental loads database was constructed by performing Life Cycle Assessment (LCA) based on detailed design data of 25 bridges. In addition, major work with high impact on environmental load were selected, and the analysis of characteristics of environmental load according to the required materials and 8 impact categories were conducted. As a result, the superstructure accounted for 42.91%. In the superstructure, remicon of the material base and PSC beam work occupied 53.13% and 31.25%. In the substructure, remicon, rebar, and cement, which are material base, accounted for more than 93%. It is expected that this major work and material information for each part of bridge can be utilized in the construction of the model, which can estimate the approximate environmental load, reflecting the characteristics of the structure in the design phase.

• Environmental and Resource Economics Review
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• v.30 no.4
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• pp.607-625
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• 2021

The objective of this study is to estimate the relationship between CO₂ emissions and both nuclear power and renewable energy generation, and compare the cost efficiencies of nuclear power and renewable energy generation in reducing CO₂ emissions in Korea. The results show that nuclear power and renewable energy generation should be increased by 1.344% and 7.874% to reduce CO₂ emissions by 1%, respectively. Using the estimated coefficients and the levelized costs of electricity by source including the external costs, if the current amount of electricity generation is one megawatt-hour, the range of generation cost of nuclear power generation to reduce 1% CO₂ emissions is $0.72~$1.49 depending on the level of external costs. In the case of renewable energy generation, the generation cost to reduce 1% CO₂ emissions is $6.49. That is, to mitigate 1% of CO₂ emissions at the total electricity generation of 353 million MWh in 2020 in Korea, the total generation costs range for nuclear power is $254 million~$526 million for the nuclear power, and the cost for renewable energy is $2.289 billion for renewable energy. Hence, we can conclude that, in Korea, nuclear power generation is more cost-efficient than renewable energy generation in mitigating CO₂ emissions, even with the external costs of nuclear power generation.

• Journal of Korean Society of Forest Science
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• v.109 no.3
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• pp.300-312
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• 2020

The growing stocks of young forests that are less than10 years of age have been excluded from the Korean forest resource statistics, despite the existence of standing trees; however, sustainable forest management and carbon removals in the forestry section require complete information regarding forest resources. This study developed a method to estimate the growing stocks for young forests from National Forest Inventory (NFI) data. After reviewing previous research on growth characteristics for young forests, we conducted stem analysis of major species, and examined stand characteristics by site index, based on real yield tables. Our statistical analysis results showed that there were few standing trees with diameters at breast height (DBH) above 6 cm in young stands, and that it would have taken 12 years, on average, to reach 6 cm DBH. This suggests that mean tree height by diameter should be assessed at the root, in order to assess growing stocks for young stands through the NFI. Moreover, the database system should be improved to differentiate tree species, since diverse shrubs, including trees, have been surveyed.

• Korean Journal of Construction Engineering and Management
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• v.24 no.3
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• pp.12-19
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• 2023

In the case of the construction industry, the relationship between process and cost should be appropriately distributed so that the finished product can be delivered at the minimum fee within the construction period. At that time, it should be considered the size of the bridge, the construction method, the environment and production capacity of the factory, and the transport distance. However, due to various reasons that occur during the construction period, problems such as construction delay, construction cost increase, and quality and reliability degradation occur. Therefore, a systematic and scientific construction technique and process management technology are needed to break away from the conventional method. The prefab(Pre-Fabrication) is a representative OSC (Off-Site Construction) method manufactured in a factory and constructed onsite. This study develops a resource and process plan optimization system for the process management of the Nodular girder, a prefab bridge girder. A simulation algorithm develops to automatically test various variables in the personnel equipment mobilization plan to derive the optimal value. And, the algorithm was applied to the Paju-Pocheon Expressway Construction (Section 3) Dohwa 4 Bridge under construction, and the results compare. Based on construction work standard product calculation, actual input manpower, equipment type, and quantity were applied to the Activity Card, and the amount of work by quantity counting, resource planning, and resource requirements was reflected. In the future, we plan to improve the accuracy of the program by applying forecasting techniques including various field data.

• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.91-98
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• 2010

This paper is on the research result for analyzing the performance of GLORY(GLobal Resource management sYstem) used for Web Server Cluster system, which was developed at ETRI(Electronic and Telecommunication Research Institute). The paper includes the definition of Web Server Cluster System, the characteristics of the system, user oriented system performance, current performance enhancement methods, computer simulation model for GLORY and its experimental results for the performance of GLORY. GLORY is composed of 2048~1,000,000 units of PCs, and is used for Internet servers. From the results of the simulation experiments, we notice that GLORY has enough capacity to fully serve the appropriate level of Internet services. Also, the results show that Web server service time is longer than that for network transmission time but requires more DNS than expected, and that 100Mbps LAN is good enough for directly connecting Internet to the Web servers while not affecting the total system performance.

• Journal of the Korean GEO-environmental Society
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• v.25 no.4
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• pp.5-12
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• 2024

In the case of creating a site in the reclaimed land (public waters), due to the nature of the coastal sedimentary ground, large-scale construction materials are required, It is necessary to utilize soft clay, which is inevitably generated during construction of the complex, as a fill material in terms of resource recycling and economic aspects (reducing the amount of embankment required). In this study, changes in the consolidation characteristics of cut-out disturbed soft clay due to the recycling of soft clay soil were identified, and a consolidation settlement design plan was proposed. Through the results of the consolidation test of the study site, the change in consolidation characteristics (compression index reduction, precede load uncountable) due to disturbance (cutting) was confirmed, the method of calculating (consolidation settlement) the filling clay layer as the composite target layer (consolidation target layer, loading load layer) was analyzed as a result consistent with the actual behavior.