• 한국작물학회지
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• 제48권6호
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• pp.506-515
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• 2003

이 논문은 한발저항성이 다른 6개 보리 품종의 한발에 따른 생장, 잎의 수분포텐셜(leaf water potential, LWP), 상대함수량(leaf relative water content, RWC), 삼투압(leaf osmotic potential, OP), 삼투조정(osmotic adjustment, OA), 팽압(leaf turgor pressure, LTP), 순광합섬, 기공전도도, 엽육전도도, 엽록소형광 등의 변화를 조사하여 비교한 결과를 요약하면 다음과 같다. 1 한발 처리시 토양수분포텐셜은 -0.05㎫이었고. 종료시에는 -0.29㎫로 저하하였다. Dicktoo-S 동보리 1호, Dicktoo-L, Dicktoo-T, 수원쌀보리 365호, 탑골보리 품종의 한발처리구 건물중은 각각 대조구(처리기간종 -0.05㎫ 유지)에 비하여 68%, 69%, 70%, 86%, 55%, 37%를 나타내어 Dicktoo 계통과 동보리1호의 한발저항성이 강하였고, 수원쌀보리 365호와 탑골보리는 한발저항성이 약하였다. 2. 한발저항성이 강한 품종은 삼투조정능력이 커서 한발처리에 따른 RWC와 LWP의 저하가 작았고 팽압유지능력이 컸다. 3. 한발처리에 따라 순광합성이 저하하였고 그 저하정도는 한발저항성이 큰 품종이 작았는데, 이는 한발저항성이 큰 품종이 기공전도도, 엽육전도도 및 PSII 최대양자수율(Fv/Fm)의 저하가 적었기 때문이었다. 4. 결론적으로 저항성이 큰 품종은 삼투조정에 의한 수분유지능력이 크고 이에 따라 광합성저하가 적어 상대적으로 생장의 감소가 적은 것으로 판단되었다.

• 한국가금학회지
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• 제22권3호
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• pp.133-144
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• 1995

One metabolism trial(Experiment I) and another respiration trial(Experiment II) were conducted to investigate the effects of dietary fiber supplementation(20% wheat bran) on the water balance, blood acid-base balance, body temperature, and metabolic rate of heat-stressed adult roosters. In Experiment I, twenty 20-wk-old SCWL roosters(BW 1.6 kg) were randomly alloted to 4 treatments with 5 birds per treatment and one per replicate. The 4 treatments were consisted of two temperature(21~22˚C vs. 34~35˚C) and two dietary fiber treatment(0% and 20% wheat bran), making Experiment I a 2x2 factorial. After 4 d of preliminary period, birds we subjected to 3-d collection period. Sixteen 20-wk-old SCWL roosters(BW 1.6 kg) were employed Experiment H, with two temperature(21~22˚C vs. 34~35˚C) and two wheat bran levels(0% and 20%). Brids were housed in individual metabolism cages under normal temperature(21~22˚C), at fed one of the experimental diet. After 4 d of preliminary period, a respiration trial with open-circuit gravimetric respiratory apparatus was carried out for each bird for 6 h, one by one, normal(20~21˚C) and hot(34~35˚C) temperatures. The ANOVA test and comparisons among treatment means were done at 5% probability level for both experiments. Results obtained from Experiment I and, II were summarized as follows, 1.The amounts of DM intake and excretion were significantly(P<.05) decreased by heat stress. The DM intake was not affected by the addition of 20% wheat bran, however, the amount of DM excretion was significantly increased by the high fiber diet. Thus, the DM metabolizability decreased significantly by the addition of 20% wheat bran. 2. The heat-stressed roosters increased the water intake and excreta moisture content significantly. Although not significant, the water intake tended to increase in roosters fed the 20% wheat bran diet. 3. The amounts of total water input and evaporative water loss were increased significantly by heat stress, and the addition of 20% wheat bran did not exert any influence on the total water input and evaporative water loss. However, roosters fed the 20% wheat bran diet increased the excreta water output significantly. 4. Neither the heat stress nor the dietary fiber did affect the blood pH, pCO2, and HCO$_3$- significantly. 5. The body temperature increased significantly by the heat stress. However, the high fiber deit failed to decrease the body temperature. 6. The heat-stressed roosters decreased the 02 consumption and C0$_2$ production, and increased the evaporative water loss significantly. However, the high fiber diet did not exert any infulence in this regard. It appears that the beneficial effect, if any, of high fibrous diet during heat stress episode may be due to the increased heat loss through the enhanced excreta water.

• 대한원격탐사학회지
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• 제31권2호
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• pp.77-83
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• 2015

잎의 수분 함유량은 식물의 건강상태를 나타내는 중요한 척도 중 하나로써, 이를 원격탐사를 활용 하여 모니터링 하는 것은 산림관리에 있어서 매우 중요하다. 본 연구에서는 식생 캐노피의 수분량을 연구하는데 유용한 지수인 Normalized Difference Water Index (NDWI)를 이용하여 한반도 산림의 water stress 정도를 알아보고자 한다. SPOT/VEGETATION S10 채널자료를 1999년부터 2013년까지 취득하여 NDWI 를 산출하였고, 데이터의 노이즈를 제거하기 위하여 단순이동평균, NDWI의 시간적 변화를 파악하기 위하 여standardized anomaly를 수행했으며, 직관적인 모니터링을 위해 NDWI anomaly를 등급화 하였다. 또한 피해면적 150 ha 이상의 대형 산불과 비교 검증을 통해, 산림 캐노피의 water stress 평가 인자로서 NDWI의 적합성을 파악하였다. 그 결과 연구 기간 중 대형 산불은 총 24회 발생하였으며 모든 발생 지점 및 인접 지역에서 음의 anomaly가 나타났다. 특히 NDWI anomaly의 등급이 'high'일 경우 대형 산불이 빈번하게 발생하는 것을 확인하였다.

• 상하수도학회지
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• 제21권2호
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• pp.151-164
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• 2007

Criteria for rehabilitation priority are discussed to evaluate structural stability of deteriorated water transport and transmission pipes, in this study. For the purposes, safety factor is introduced and estimated by measuring tensile strength and by analyzing stress caused by the internal-external loads working on buried pipe body. Related informations are surveyed and collected under various conditions in the fields by digging out and the structural stability is assessed. In the evaluation results of structural safety, it is shown that steel pipe is more affected by external load than internal load. The average external load is estimated as $53.7kg/cm^2$ and total hoop stress is estimated by $2676.5kg/cm^2$. Also, Poisson effect into longitudinal direction due to internal and external loads is most influential on hoop stress. The calculated safety factors of hoop stress are ranged from 0.7 to 5.2 with average value of 2.1, considering a bending stress to longitudinal direction. The decision of rehabilitation priority by safety factors show that structural safety of CIP sample 1(S1) was assessed at the lowest order with safety factor value, 0.7 and that of DI sample 15(S15) was evaluated as the most stable in structural aspect.

• Biomolecules & Therapeutics
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• 제12권4호
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• pp.242-249
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• 2004

The main aim of this study was to investigate stress related activities of Sun-ginseng extract as a candidate for anti-stress-related functional supplement by comparing its effect to those of red ginseng, which is also known to alleviate stress. Normal group was not exposed to stress while the control group was exposed to stress. Rats were orally administered once a day with 200 mg red ginseng (RG) extract, 100 or 200 mg Sun-ginseng (SG) extract/kg body weight. Mice were given water containing 400 mg red ginseng extract, 200 or 400 mg SG/100 mL potable water. Rats were given supplements for 5 days without stress, and 5 days with restraint and electroshock stress. After final stress, stress-related behavioral changes of experimental animals were recorded and levels of blood corticosterone were measured. Mice were given supplements for 5 days through drinking water, and then fatigue related motor activity were recorded. SG-supplementation partially blocked stress effect on locomotion and elevated plus maze test in rats, and also partially blocked stress-induced behavioral changes such as freezing, burrowing, smelling, facewashing, grooming and rearing behavior in rats. SG-supplementation decreased blood corticosterone level which is increased by stress in rats. Effects of SG may not be modulated by GABAnergic nervous system. SG-supplementation prolonged swimming time and staying time on the wire and rotarod wheel in mice. These results suggest that SG partially protects living organisms from stress attack in some cases and thus has the potential to be used as a functional food to alleviate stress response.

• 한국농공학회지
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• 제30권4호
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• pp.134-153
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• 1988

This paper was carried out to investigate the existence of a unique stress- strain behavior by obtaining some factors influencing the time dependent stress- strain behavior of clay. The results obtained from this study were summarized as follows ; 1. The relationship between stress ratro and strain in normally consolidated clay was in- dependent on pre-shear consolidation pressure. Therefore, shear strain could be expressed as a function with stress ratio. 2. The constitutive equation of shear strain on Modified Carn Clay Model coincided better with the observed value than Cam Clay Model. 3. The relationships between deviator stress and shear strain, between pore water pressure and shear strain were unified by the mean equivalent pressure. 4. The shear strain contour in norrnally consolidated clay was increased linearly through origin, but that in overconsolidated clay was not in accordance with the result of the former. 5. Because the effective stress path of normally consolidated clay was unified by the mean equivalent pressure, state boundary surface in (e,p,q) space was transformed into two dimensional surface. But it was considered to be suitable that the unified stress- strain in overconsolidated clay be expressed by a function with overconsolidation ratio. 6. The deviator for constant strain was increased linearly with increment of strain rate ($\varepsilon$) on semi-log scale, but pore water pressure was decreased. 7. The behavior of stress relaxation was transformed from linear to curvilinear with inc - rement of strain rate before stress relaxation test, and pore water pressure was increased in total range. 8. The strain of creep was increased linearly with increment of time on semi-log scale. The greater the strain rate before creep test became, the greater the increment of strain of creep became. And the pore water pressure during creep test was increased generally with increment of time on semi-log scale.

• Journal of Advanced Marine Engineering and Technology
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• 제35권7호
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• pp.930-937
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• 2011

The characteristics of mean velocity and turbulence have been analyzed in the circular open channel flow using PIV measurement data for a wide range of water depth. The measured data are fitted to a velocity distribution function over the whole depth of the open channel. Reynolds shear stress and mean velocity in wall unit are compared with the analytic models for fully-developed turbulent boundary layer. Both the mean velocity and Reynolds shear stress have different distributions from the two-dimensional boundary layer flow when the water depth increases over 50% since the influence of the side wall penetrates more deeply into the free surface. The cross-stream Reynolds normal stress also has considerably different distribution in view of its peak value and decreasing rate in the outer region whether the water depth is higher than 50% or not.

• 한국농공학회지
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• 제43권6호
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• pp.103-112
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• 2001

The development of infrared thermometry has led many researchers to use plant temperatures, and specifically the temperature of the crop canopy in the field, for estimating the water stress of a crop. The purpose of this study was to evaluate the role of leaf temperature in irrigation scheduling. An experiment was carried out in a greenhouse with chinese cabbage. Leaf temperature was measured with infrared thermometry and evapotranspiration of the crop was measured by lysimeters. Influence of the difference between leaf temperature and air temperature on crop evapotranspiration was evaluated under varying water stress condition. A further objective was to evaluate the effect of other climatic variables on the relationship between evapotranspiration and temperature difference between leaf and air. A statistical model for estimating evapotranspiration using the temperature difference, relative humidity. and radiation was developed and tested. Crop water stress index was calculated using vapour pressure deficit and the temperature difference. Relations between the crop water stress index and crop evapotranspiration was tested. The index was closely related with evapotranspiration.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 추계 학술논문 발표대회
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• pp.27-28
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• 2018

In this study, water vapor pressure and restrained stress were evaluated by ring-type restrained condition for compressive strength 60 and 80MPa concrete. Experimental results show that the 80MPa concrete has higher water vapor pressure and restraint stress than the 60MPa concrete, resulting in spalling occurrence. It is because, the higher the compressive strength of the concrete, the more dense the internal structure is formed.

• 대한기계학회논문집A
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• 제24권1호
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• pp.156-162
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• 2000

Sensitized STS 304 stainless steel crack growth rate(CGR) in high temperature water was investigated under trapezoidal wave loading test using fracture mechanics techniques. The CGR, due to stress corrosion cracking(SCC), were systematically measured as a function of the stress intensity factor and stress. holding time under trapezoidal wave loading. In high temperature water, CGR was enhanced by a synergistic effects in combination with an aggressive environment and mechanical damage. The CGR, $(da/dN)_{env}$ was basically described as a summation of the environmentally assisted crack growth rate $(da/dN)_{SCC}$, $(da/dN)_{CF}$ and fatigue crack growth rate in air $(da/dN)air,. The CGR, $(da/dN)_{env}$, increased linearly with increasing stress holding time. The CGR, $(da/dN)_{SCC}$ decreased linearly with increasing stress holding time. Fracture surface mode varied from trans-granular cracking to inter-granular cracking with increasing stress holding time.