• Journal of the Korean GEO-environmental Society
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• v.7 no.4
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• pp.43-52
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• 2006

There were huge damages of human beings and their properties in many areas of the basin of the Nak-Dong river by the unusual weather and the localized downpour recently. In this research against disasters, we want to know strength of the cemented sand that is mixed with cement and poor-graded sand, to estimate CSG(Cemented Sand and Gravel) method used coffer dam in Japan, which is the materials of riverbed in the basin of the Nak-Dong river for levee's construction. For that, we want to provide the fundamental data which need in the examination of adaptation of levee's material, design and analysis by investigating compressive strength by curing period and cement content, elastic modulus and stress by transformation from compaction test, CBR test, unconfined compression test and triaxial compression test as changing cement content from 2% to 8% at two sites in the basin of the Nak-Dong river.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.187-194
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• 2020

The T&E (Test and Evaluation) results were applied for a judgment basis to decide the developmental process of system engineering for efficient weapon system R&D (Research and Development). During the OT&E (Operational Test and Evaluation) and DT&E (Development Test and Evaluation), an environmental test is essential for weapon system development owing to their highly exposed operational conditions. Based on the MIL-STD-810, MIL-HDBK-310, and AECTP 200, the ROK armed forces recommended operating temperatures for the ROK weapon system and applied this to the DT&E and OT&E. This study examined the compatibility of Korean temperature guidelines for stockpile material considering recent climate change. Moreover, this study analyzed the data from hourly measured temperatures on 101 observatories during 60 years, from 1960 to 2020, and percentage (0.5%, 1%, 5%, and 10%) and the 𝜎 (3𝜎, 2𝜎, and 1𝜎) frequency of occurrence on rigorous hot (August) and cold (January) periods, respectively. The results indicate that the highest temperature was 41℃, and the 0.5% frequency of occurrence was 37.0℃. In the case of the cold period, the lowest temperature was -32.6℃ and the 0.5% frequency of occurrence was -21.1℃. By considering the previously recommended operating temperature range for a general ground system, -30 ~ 40℃, regional operation probability is recognized 99.999%. Despite the recent abnormal climate change from global warming, the Korean temperature guidelines are compatible with the stockpile material environmental test.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.440-440
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• 2012

본 연구에서는 수질관리 및 기후변화(온실가스 저감) 등에 부응할 수 있는 SRI 벼재배 방법을 국내 논에 적용하여 농업비점오염원과 온실가스 저감효과를 측정하고 비교하여 SRI의 환경개선효과를 평가하고자 하였다. 시험포는 대조구인 상시담수처리구(관행, 재식거리 $30{\times}15cm$)와 SRI 물관리 처리구로 조성하였다. 각 시험포에는 관개배수시설 및 관개량을 측정할 수 있는 수도계량기, 유출량 측정을 위한 플륨 및 수위계 그리고 온실가스(메탄 및 이산화질소)를 측정하기 위한 아크릴재질의 Chamber를 설치하였다. 관행 및 SRI 시험포에 이앙할 모의 재배품종으로 오대벼를 공시하고 모든 시험포의 경우 1주당 3-5본씩 기계이앙을 실시하였으며, 물관리를 제외한 시비와 제초 등의 영농관리는 동일하게 수행하였다. 메탄($CH_4$)과 아산화질소($N_2O$)는 주 2회, 오전 9시 12시에 60 mL 주사기로 주기적으로 시료를 채취하여 GC로 분석하였다. 그리고 관개기간동안 관개량, 강우량 그리고 강우 유출량을 측정하고 수질시료를 채취하여 오염부하를 산정하였다. SRI 시험포의 SS, $COD_{Cr}$, $COD_{Mn}$, BOD, TN, TP의 총 오염부하량은 각각 583 kg/ha, 210.8 kg/ha, 70.1 kg/ha, 30.7 kg/ha, 56.1 kg/ha, 3.55 kg/ha로서 관행 시험포의 오염부하량에 비해 27.1~46.0%의 오염물질 저감 효과를 보였다. 그리고 각 시험포별 온실가스 메탄과 아산화질소의 총 배출량을 지구온난화잠재력(GWP)으로 환산하여 이산화탄소($CO_2$) 기준으로 산정한 결과, 관행은 14.2 톤/ha 그리고 SRI 물관리 처리구 4.0 톤/ha로 관행 대비 SRI 처리구에서 71.8%의 온실가스 감축효과를 나타내었다. 따라서 SRI 벼재배기술은 논 비점오염부하 및 온실가스 저감을 위한 효과적인 최적영농관리방법인 것으로 판단된다.

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.283-291
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• 2013

This experiment was carried out for the selection of suitable cultivars on the green and fairway at the mountain area. The climate data showed that differences of altitude influenced greater than latitude on temperature and rainfall when compared with 3 areas of the central of Gyeong-gi and Yeong-seo, and the mountain area at Yeong-seo. The plot was prepared with the USGA profiles for green and modified California style for fairway at the mountain golf course in Wonju, Korea. The growth characteristics were compared on two different profiles for 3 years of growing seasons after seeding with 5 creeping bentgrass cultivars. 'T-1' and 'CY-2' showed a rapid greenup compare with other cultivars in spring of 2010 with the both green and fairway mowing height. However, 'Penncross' resulted the slowest among cultivars. 'T-1' showed the most prominent visual quality of overall rate and the deepest root length after one year of seeding, while 'Penncross' showed an excellent result of root length and weight during summer season. However, 'Penn A-1' had an imperial result in that season. Comparison of the growth characteristics under green and fairway conditions, 'T-1' and 'CY-2' showed exellent overall results at the mountain area at Yeong-seo area in Korea.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.1
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• pp.121-133
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• 2020

Globally, the frequency and intensity of abnormal climate events are increasing. Since this can directly damage lives and property, it is important to establish and implement an appropriate maintenance strategy in response to abnormal weather. Facilities built in cold regions where cold wave or heavy snow occurs frequently can be more damaged by freeze-thaw than facilities located in other regions. However, there are no clear criteria for quantitatively identifying the damage of freeze-thaw and how to cope with it. Therefore, based on the results of indoor freezing tests, the freezing conditions considering regional climate characteristics were selected as one day at -14℃, two days at -7℃ or three days at -5℃. As a result, it was confirmed that they were in the freeze-thaw environment in order of Daegwallyeing (8.3 times), Cheorwon (5.3 times) and Taebeak (4.9 times) in Gangwon region. Through this study, the evaluation criteria of freeze-thaw of road tunnels were newly proposed. The freeze-thaw evaluation criteria of the road tunnel presented in this study can be used for the quantitative evaluation and maintenance strategy of tunnels in cold regions.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1070-1075
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• 2007

과거의 이수나 치수기능에 역점을 둔 하천개발이 국민의 하천환경에 대한 관심이 증대되면서 인공화 된 하천을 원래의 자연스러운 하천상태로 되돌리고자 하는 다각적인 노력이 모색되어 하천에 대한 복원계획을 세우고 자연형 하천공법을 개발, 적용하기 위하여 여러 기관에서 각각의 연구목적에 맞게 시험유역에 운영하고 있다. 그러나 소하천은 지역적인 특성이 두드러지고 공간적 분포와 기후적 특성이 다양하기 때문에 소하천 특성변화에 따른 지속적인 자료구축을 위해 유출 및 하도형상등 수리 수문학적 변화특성과 하천환경 특성을 분석하고 모니터링 함으로써 자연형 하천의 시공 후 발생하는 여러 가지 문제에 대한 검증과 설계 시에 세운 목표에 대해서 목표의 달성여부를 검토해야 한다. 하천정비후의 정확한 변화 상태를 검토하여 적용된 공법에 대한 타당성을 검토하여야 하며 각 분야별 세부평가 기준도 작성할 필요가 있다. 본 연구는 행정자치부 선정 소하천정비 시범지구로 지정된 봉황소하천에 대해 유역의 시공전후 모니터링을 실시하여 소하천의 환경기능을 향상시킬 수 있는 소하천 정비공법 개발을 위한 지속적이고 일관성 있는 수리 수문 자료의 축적과 하천환경 개선과 향후 자연형 소하천정비 공법의 기초자료로 활용하는 것이 목적이다. 연구 대상지역인 봉황천은 전라남도 강진군에 위치하고 있으며 시범구간 약 1km에 대해 2003년부터 2006년까지 수질, 수리, 생태계 모니터링을 실시하여 시공전후로 비교하였다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.2
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• pp.108-121
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• 2021

Field studies at Suwon, Cheorwon, and Jinbu were carried out to determine the relationship between mean temperature from transplanting to heading (MT) and growth at heading stage of rice. P lant height (P H) and dry weight (DW) at heading stage were significantly correlated with MT, showing second degree polynomials. The optimal temperatures for PH and DW were 23.2 ℃ and 22.8 ℃, respectively. Little differences in rice growth among soils collected from the experimental sites and the temperature-response in a phytotron study supported that MT was the main determinant of the growth shown in the field study. Though number of days to heading increased as MT decreased, cumulative temperatures (CT) affected by sites and MT for given varieties were fairly constant. When applying specific CT for each of the varieties to the temperature in North Korea, (1) five regions (Kaesong, Haeju, Sariwon, Nampo, Pyongyang) were suitable for early to mid-maturing varieties and (2) 14 regions (Yongyon, Singye, Anju, Kusong, Sinuiju, Changjon, Wonsan, Hamhung, Pyonggang, Yangdok, Huichon, Supung, Sinpo, Kanggye) were suitable only for early-maturing varieties. In (1) regions, the similar extent of growth with that in Suwon could be achieved when mid-maturing varieties grown in Suwon are cultivated. Among (2) regions, early-maturing varieties are expected to demonstrate the similar extent of growth with that in Cheorwon in 9 regions except Hamhung, Kanggye, Pyonggang, Yangdok, and Sinpo. For Hamhung and Kanggye, the target PH was assessed as 4cm higher than that shown in Cheorwon. P lant height of 8-14cm and DW of 2-4g per hill greater than those shown in Cheorwon were the target growth for P yonggang, Yangdok, and Sinpo to attain the similar amount of growth with that in Cheorwon. It is suggested that rice varieties for North Korea could be bred by adjusting the target growth at the breeding sites in South Korea.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.4
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• pp.296-304
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• 2018

The objective of this study was to analyze the impact of climate change on rice yield and quality. Experiments were conducted using SPAR(Soil-Plant-Atmosphere-Research) chambers, which was designed to create virtual future climate conditions, in the National Institute of Crop Science, Jeonju, Korea, in 2016. In the future climate conditions($+2.8^{\circ}C$ temp, 580 ppm $CO_2$) of year 2051~2060 according to RCP 8.5 scenario, elevated temperature and $CO_2$ accelerated the heading date by about five days than the present climate conditions, resulted in a high temperature environment during grain filling stage. Rice yield decreased sharply in the future climate conditions due to the high temperature induced poor ripening. And the spikelet numbers, ripening ratio, and 1000-grain weight of brown rice were significantly decreased compared to control. The rice grain quality was also decreased sharply, especially due to the increased immature grains. In the future climate conditions, expression of starch biosynthesis-related genes such as granule-bound starch synthase(GBSSI, GBSSII, SSIIa, SSIIb, SSIIIa), starch branching enzyme(BEIIb) and ADP-glucose pyrophosphorylase(AGPS1, AGPS2, AGPL2) were repressed in developing seeds, whereas starch degradation related genes such as ${\alpha}-amylase$(Amy1C, Amy3D, Amy3E) were induced. These results suggest that the reduction in yield and quality of rice in the future climate conditions is likely caused mainly by the poor grain filling by high temperature. Therefore, it is suggested to develop tolerant cultivars to high temperature during grain filling period and a new cropping system in order to ensure a high quality of rice in the future climate conditions.

• Composites Research
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• v.36 no.4
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• pp.281-287
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• 2023

Environmental pollution from waste and the climate crisis, due to rising global average temperatures, are reaching critical levels threatening human survival. Research is ongoing across various fields to solve this problem, with a key focus on developing eco-friendly, carbon-neutral materials. Our study aimed to integrate natural fibers, known for their environmentally friendly properties and lower carbon emissions, with carbon fibers. In general, combining high-strength and low-strength materials results in intermediate properties. However, we found that certain properties in our study exceeded those of typical carbon fiber composite materials. To validate this, we produced both carbon fiber composite materials and carbon fiber/natural fiber hybrid composite materials. We then compared their mechanical properties using a range of specific tests. Our results revealed that the hybrid composite material exhibited superior bending strength and fracture toughness compared to the carbon fiber composite material. We also identified the underlying mechanisms contributing to this strength enhancement. This breakthrough suggests that the use of hybrid composite materials may allow the production of stronger structures. Moreover, this can play a significant role in mitigating environmental pollution and the climate crisis by reducing carbon emissions, a major contributing factor to these global challenges.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.166-174
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• 2018

Potato(Solanum tuberosum L.) is one of the major food crop in the world following rice, wheat, and maize. It is thus important to project yield predict of potato under climate change conditions for assessment of food security. A crop growth modelling is widely used to simulate crop growth condition and total yield of various crops under a given climate condition. The decision support system for agrotechnology transfer (DSSAT) cropping system model, which was developed by U.S. which package integrating several models of 27 different crops, have been used to project crop yield for the impact assessment of climate change on crop production. In this study, we simulated potato yield using RCP 8.5 climate change scenario data, as inputs to the DSSAT model in five regions of Korea. The genetic coefficients of potato cultivar for 'superior', which is one of the most widely cultivated potato variety in Korea were determined. The GenCalc program, which is a submodule of the DSSAT package, was used to determine the genetic coefficients for the superior cultivar. The values of genetic coefficients were validated using results of 39 experiments performed over seven years in five regions. As a case study, the potato yield was projected that total yields of potato across five regions would increase by 26% in 2050s but decrease by 17% in 2090s, compared with 2010s. These results suggested that the needs for cultivation and irrigation technologies would be considerably large for planning and implementation of climate change adaptation for potato production in Korea.