• 한국환경과학회지
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• 제22권7호
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• pp.885-893
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• 2013

The purpose of this study was to analyze the effects of partial solar eclipse on 21 May 2012 in Korea on meteorological variables in Busan. 0800 LST(Local Standard Time) solar radiation was similar or lower than 0700 LST solar radiation, and sunshine duration decreased by 0.2~0.5 hours in Busan and great cities under the influence of the partial solar eclipse. Temperature drop due to the partial solar eclipse was $0.2{\sim}2.0^{\circ}C$, time taken to arrive at maximum temperature after onset of eclipse was 8~62 minutes, and time taken to arrive at minimum temperature after maximum eclipse was -9~17 minutes in Busan. Change of wind speed was negligible as partial solar eclipse occurred in the morning. Soil temperature of 5 cm was minute as well, the increase of soil temperature due to sunset was delayed by more than 1 hour.

• 한국유기농업학회지
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• 제19권spc호
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• pp.234-237
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• 2011

This study was carried out to investigate the effect of soil covering materials such as rice bran, rice hull and saw dust on garlic growth through a field experiment in wintertime. Rice bran was the smallest in term of particle size, but it recorded the highest level of bulk density. The missing plant rate after winter season was relatively high, 59.3%, and that of soil covering materials stood at the low level of 10%. Other growth factors recorded the highest level during application of rice bran. In terms of chemical properties of soil-covering materials, rice bran recorded the highest level of 1.84, 2.34 and 0.16% in the content of N, P, and K, respectively. The subsoil temperature was higher by application of rice bran as compared to that of other materials which stood at the lowest temperature ($-9^{\circ}C$).

• 한국지반신소재학회논문집
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• 제14권2호
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• pp.57-70
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• 2015

본 논문에서는 지열활용 지반구조물 적용시 주변 지반에 부과되는 온도변화 사이클이 흙의 물리적 역학적 특성에 미치는 영향에 대한 내용을 다루었다. 이를 위해 모래와 화강풍화토를 대상으로 다양한 온도변화 조건을 구현하고 이에 따른 흙의 입자구조 및 열전도특성 변화 경향을 고찰하였다. 아울러 다양한 온도변화에 노출된 시료를 이용하여 시편을 조성한 후 삼축압축시험을 수행하고 그 결과를 토대로 온도변화가 시편의 응력-변형률-강도 톡성에 미치는 영향을 검토하였다. 그 결과 온도변화 사이클은 흙의 입자구조 및 열전도율에 큰 영향을 미치지 않는 것으로 검토되었다. 또한 임의 반복 사이클 $N_{hc}$에 있어 가열시간이 $H_d=2{\sim}8hrs$ 변화함에 따라 최대 축차응력이 15%이상 감소하는 것으로 나타나 가열-냉각 반복작용에 의한 흙의 강도특성 변화는 흙의 종류에 따라 달라 질수 있는 것으로 검토되었다.

• 한국물환경학회지
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• 제25권6호
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• pp.821-831
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• 2009

The study was aimed to assess the expected impact of climate change on the water cycle and soil losses in Daecheong Reservoir watershed, Korea using the Soil and Water Assessment Tool (SWAT) that was validated for the watershed in a previous study. Future climate data including precipitation, temperature and humidity generated by introducing a regional climate model (Mesoscale Model Version 5, MM5) to dynamically downscale global circulation model (European Centre Hamburg Model Version 4, ECHAM4) were used to simulate the hydrological responses and soil erosion processes in the future 100 years (2001~2100) under the Special Report on Emissions Scenario (SRES) A1B. The results indicated that the climate change may increase in the amount of surface runoff and thereby sediment load to the reservoir. Spatially, the impact was relatively more significant in the subbasin Bocheongcheon because of its lower occupation rate of forest land compared to other subbasins. Seasonally, the increase of surface runoff and soil losses was more significant during late summer and fall season when both flood control and turbidity flow control are necessary for the reservoir and downstream. The occurrence of extreme turbidity flow events during these period is more vulnerable to reservoir operation because the suspended solids that remained water column can be resuspended by vertical mixing during winter turnover period. The study results provide useful information for the development of adaptive management strategy for the reservoir to cope with the expected impact of future climate change.

• 농촌계획
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• 제16권4호
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• pp.109-116
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• 2010

Climate change is known to affect both natural and managed ecosystems, and will likely impact on the terrestrail carbon balance. This paper reports the effects of climate change on spatial-temporal changes in carbon reductions in South Korea's during 2000-2100. Future carbon (C) stock distributions are simulated for the same period using various spatial data sets including land cover, net primary production(NPP) and leaf area index (LAI) obtained from MODIS(Moderate Resolution Imaging Spectroradiometer), and climate data from Data Assimilation Office(DAO) and Korea Meteorological Administration(KMA). This study attempts to predict future NPP using multiple linear regression and to model dependence of soil respiration on soil temperature. Plants store large amounts of carbon during the growing periods. During 2030-2100, Carbon accumulation in vegetation was increased to $566{\sim}610gC/m^2$/year owing to climate change. On the other hand, soil respiration is a key ecosystem process that releases carbon from the soil in the form of carbon dioxide. The estimated soil respiration spatially ranged from $49gC/m^2$/year to $231gC/m^2$/year in the year of 2010, and correlating well with the reference value. This results include Spatial-Temporal C reduction variation caused by climate change. Therefore this results is more comprehensive than previous results. The uncertainty in this study is still large, but it can be reduced if a detailed map becomes available.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.361-367
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• 2009

The criteria such as ASTM recommends that the zero reading process of CPT must be performed in the same temperature condition with underground in order to reduce the effect of temperature. However, this method can not consider the change of temperature occurred during penetration. In this study, ultra small size temperature sensor with 0.5mm in diameter is manufactured to estimate and compensate the effect of temperature by using FBG sensor. The continuous temperature changes are monitored during cone penetration by using FBG temperature sensor installed in cone penetrometer. The temperature compensated tip resistances show the uniform and similar distributions with depth in different with originally measured tip resistance in cohesive soil. This study verifies that the tip resistances measured by previous zero reading method are affected by the change of underground temperature, and suggests the new temperature compensation technique using by FBG temperature sensor.

• 한국환경복원기술학회지
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• 제26권3호
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• pp.19-28
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• 2023

The purpose of this study is to estimate carbon dioxide emissions from soil microbial respiration by forest type of Sobaeksan National Park. As a result of estimating the annual soil microbiological respiration volume by forest type in Sobaeksan National Park, broad-leaved forests, coniferous forest, artificial forests were similar to around 19.5 CO₂-ton/ha/yr. In the case of coniferous forests in sub-alpine and grassland near Birobong Peak, 12.2 CO₂-ton/ha/yr and 8.1 CO₂-ton/ha/yr, respectively, were lower than general forest areas. And as a result of analyzing the changes in soil microbiological respiration rate according to forest type in Sobaeksan National Park, the soil microbiological respiration rate in coniferous forests, broad-leaved forests, artificial forests, and sub-alpine areas was the highest in the July survey in summer and the lowest in November in late autumn. The change in soil microbial respiratory volume according to the measurement time in Sobaeksan National Park was the highest between 12:00 and 16:00, when the soil temperature was generally the highest among the days. It is known that the soil temperature is relatively low and the amount of soil microbial respiration decreases during winter, and the change in respiratory volume over the measurement time during the day was the smallest in November, when the amount of soil microbial respiration was relatively smaller than the May-September survey. However, this study has limitations in revealing the causal relationship of various environmental factors that affect the soil microbial respiration. Therefore, it is suggested that long-term research and investigation of various factors affecting soil respiration are needed to understand the carbon cycle of forest ecosystems.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.733-738
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• 2004

Recently continuous welded rail is generally used to ensure running performances and to overcome the problems such as structural vulnerability and fastener damage at the rail expansion joint. Though the use of continuous welded rail on bridge has the advantage of decreasing the vibration and damage of rail, it still the risk of buckling and breaking of rail due to change of temperature, starting and/or breaking force, axial stress concentration and so on. So, VIC code and many methods has been developed by researchers considering rail-bridge interaction. Although there are many research concerning stability of continuous welded rail about temperature change on bridge and starting and/or breaking force, the study of continuous welded mil for earthquake load is still unsufficient. In this study, the nonlinear seismic response analysis of continuous welded rail on bridge considering soil-structure interaction, geotechnical characteristic of foundation and earthquake isolation equipment has been performed to examine the stability of continuous welded rail.

• 아시안잔디학회지
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• 제22권2호
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• pp.133-140
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• 2008

한지형 잔디는 하절기 온도가 $30^{\circ}C$ 이상까지 올라가는 우리나라에서 뿌리와 줄기의 성장이 급격히 저하되고 심하면 고사하게 된다. 기온의 상승으로 인한 지온 상승은 잔디뿌리에 스트레스가 되며 그 스트레스는 호르몬의 불균형적인 형성으로 지상부 생장 및 광합성, 증산작용 등의 여러 매카니즘에 많은 영향을 미치게 된다. 이러한 문제를 해결하기 위해 토양내 수분함량을 조절하기도 하고 유기물 함량을 조절하여 지온의 상승을 제한함으로서 잔디의 생육부진을 해소하는 연구도 수행되었다. 본 실험은 토양 수분의 변화에 따른 토양 온도의 변화 양상을 분석하고, 잔디 재배지에서의 토양 깊이와 수분 함량에 따른 열 전도 기작과 열 환경 변화에 따른 직접적인 잔디 생육(생산량, 녹도, 건조피해, 고온피해 등)에 미치는 영향을 연구하였다. 공시 초종으로 Kentucky bluegrass(Poa pratensis L.)를 선정하였고 각각의 실험구는 수분함량에 따라 25%, 33%, 40%의 3가지로 구분하여 처리하였다. 토양온도측정 센서를 각 실험구에 깊이 12cm 지점과 2cm 지점에 각각 2개씩 즉, 한 실험구당 4개의 토양온도측정 센서를 설치하여 매 5분마다 온도변화를 측정하였다. 수분함량에 따른 온도변화는 수분함량이 33% 일 때 가장 낮게 측정되었다. 잔디의 생육상태를 비교하여 볼 때 수분 함량이 33% 일 때 생육이 가장 양호하였으며 40% 일 때 가장 생육이 불량하였다. 하절기 고온 환경에서 한지형 잔디인 Kentucky bluegrass의 생육은 토양 수분함량에 따라 큰 영향을 받지만, 장마기에 잔디가 침수된 환경에서 토양 수분 함량을 최소한 33%까지 감소시켰을 경우에는 잔디 생육에 큰 영향을 받지 않을 것으로 사료된다.

• 아시안잔디학회지
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• 제4권1호
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• pp.42-48
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• 1990

Experiments were conducted to investigate the soil freezing depth and pattern with freezing measuring instruments during 1988-l989 winter season in Kangwon province. Freezing measuring instrument was made with acrylic pipes which were consisted of inner and outer parts. Inner pipe was filled with 0.01 % methylene blue solution and rubber hose to protect pipe breakdown by solution freezing. Freezing measurements were carried out by observing discoloration of methylene blue solution. Moisture content of evergreen trees and ground cover plants was also examined in the winter season. The observed results are as follows: 1.In the land of I OOM above sea level, soil freezing depth became deeper as the sum of Accumulated degree-days of temperature below 0˚C(0˚C . day) increased: Soil freezing depth was 30-40cm at l00˚C, 42-43cm at 150˚C, and 47cm at 200˚C day 2.Soil freezing with vinyl mulching was less developed by l3cm at l00˚C with sum of subzero temperature, by l7cm at 200˚C than that of the bare ground. Soil of rich hulls mulching with 4Ocm was not frozen until soil freezing at the bare ground was developed to 25cm depth. 3.Cashmeron mulching was more effective than felt mulching in the heat insulation of soil. 4.Thawing of soil was done from the lowest part of the frozen in the ground to upward in the beginning and after that it was done from the surface of frozen soil to downward. Finally thawing was completed at the middle of frozen soil.