• Asian-Australasian Journal of Animal Sciences
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• 제31권12호
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• pp.1890-1896
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• 2018

Objective: As the climate changes, it influences ruminant's feed intake, nutrient digestibility, rumen methane production and emission. This experiment aimed to evaluate the effect of feeding Sweet grass (Pennisetum purpureum cv. Mahasarakham; SG) as a new source of good quality forage to improve feed utilization efficiency and to mitigate rumen methane production and emission. Methods: Four, growing crossbred of Holstein Friesian heifers, 14 months old, were arranged in a $4{\times}4$ Latin square design to receive four dietary treatments. Treatment 1 (T1) was rice straw (RS) fed on ad libitum with 1.0% body weight (BW) of concentrate (C) supplementation (RS/1.0C). Treatment 2 (T2) and treatment 3 (T3) were SG, fed on ad libitum with 1.0% and 0.5% BW of concentrate supplementation, respectively (SG/1.0C and SG/0.5C, respectively). Treatment 4 (T4) was total Sweet grass fed on ad libitum basis with non-concentrate supplementation (TSG). Results: The results revealed that roughage and total feed intake were increased with SG when compared to RS (p<0.01) while TSG was like RS/1.0C treatment. Digestibility of nutrients, nutrients intake, total volatile fatty acids (VFAs), rumen microorganisms were the highest and CH4 was the lowest in the heifers that received SG/1.0C (p<0.01). Total dry matter (DM) feed intake, digestibility and intake of nutrients, total VFAs, $NH_3-N$, bacterial and fungal population of animals receiving SG/0.5C were higher than those fed on RS/1.0C. Reducing of concentrate supplementation with SG as a roughage source increased $NH_3-N$, acetic acid, and fungal populations, but it decreased propionic acid and protozoal populations (p<0.05). However, ruminal pH and blood urea nitrogen were not affected by the dietary treatments (p>0.05). Conclusion: As the results, SG could be a good forage to improve rumen fermentation, decrease methane production and reduced the level of concentrate supplementation for growing ruminants in the tropics especially under global climate change.

• Ocean and Polar Research
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• 제41권3호
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• pp.159-168
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• 2019

Understanding the interaction between climate and the water cycle is critical especially in a drought sensitive region such as California. This study explored hydrologic changes in central and southern California in relation to the glacial-interglacial climate cycles over the last 30 thousand years. To do this, we reconstructed paleovegetation using plant wax carbon isotopic compositions (${\delta}^{13}C$) preserved in marine sediment cores retrieved from the central California continental shelf (ODP Site 1018) and Santa Barbara Basin (ODP Site 893A). The results were then compared to the existing sea surface temperature (SST) and pollen records from the same cores to understand terrestrial hydrology in relation to oceanographic processes. The Last Glacial was generally dry both in central and southern California, indicated by grassland expansion, confirming the previously suggested notion that the westerly storm track that supplies the majority of the precipitation in California may not have moved southward during the glacial period. Southern California was drier than central California during the Last Glacial Maximum (LGM). This drying trend may have been associated with the weakening of the California Current and northerly winds leading to the early increase in SST in southern California and decline in both offshore and coastal upwelling. The climate was wetter during the Holocene in both regions compared to the glacial period and forest coverage increased accordingly. We attribute this wetter condition to the precipitation contribution increase from the tropics. Overall, we found a clear synchronicity between the terrestrial and marine environment which showed that the terrestrial vegetation composition in California is greatly affected by not only the global climate states but also regional oceanographic and atmospheric conditions that regulate the timing and amount of precipitation over California.

• 한국해양학회지
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• 제29권1호
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• pp.42-49
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• 1994

한국 서해의 조수 퇴적층 (조간대와 조하대)과 내대륙붕 퇴적층의 퇴적상 연구에 따른 방사성 탄소(/SUP 14/C)의 연령층에 기초하여, 현세 (Holocene)의 해수면 상승과 선현세 (Pre-Holocene) 해수면 변동의 사실을 규명하였다. 또한 황해 해저 퇴적층의 지구물리적 탐사(탈성파 탐사)에 의하여, 지난 최대 빙하 발달 시기 (Glacial Maximum) 동안의 건조 한냉한 기후하에서 형성된 사막 사구층과 풍성 황토층의 존재를 제안하였다. 황해 천수만 조수 퇴적층 (조간대)에 의하여 부정합적으로 피복되고 있는 간월도층은 한냉한 빙하기후에 의한 결빙구조 즉, 특수한 cryogenic structure를 가지 며, 절대 연령이 (약 16900 yrBP)이다. 고군산도와 신시도의 연근해저 시추자료 (약 20∼23 m의 시추길이)의 암상과 탄성파 자료를 분석하므로서 도출된 퇴적환경을 기초 로 하여 협재된 토탄의 /SUP 14/C 의 연령을 측정하였고 결과적으로 국내에서 처음으 로 선현세의 interstadial (약 3000 yr BP) 전후의 고해수면 상대위치(고해안선)를 제 시 하였다.

• International Journal of Advanced Culture Technology
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• 제6권3호
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• pp.178-186
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• 2018

Generally, in terms of the development of irrigation scheme, the efficient water resource management that supplies the irrigation water in consideration of the required time and accurate quantity to grow the crop should be conducted. The water resource assessment should precede to supply the irrigation water efficiently. The water resources assessment is divided into the water requirement analysis and the water availability assessment. In case of Korea, the major crop is paddy rice unlike crops of Africa, such as sugarcane, maize, and cassava, etc. Because it is not familiar with the method for upland irrigation development in tropical area, it needs to know the water resources assessment for irrigation scheme development about these crops. The Natama Scheme in Chiradzulu District of the Southern Malawi was selected as study area, which has tropical climate. From the collected meteorological data, the evapotranspiration was analyzed by Penman-Monteith Method and the effective rainfall was analyzed by USDA Soil Conservation Service Method. This study displays the results that for study area, the evapotranspiration varies from 2.80 mm/day to 5.51 mm/day and the effective rainfall varied from 2.1mm to 149.0mm. According to the selected crop (Green Maize, Dry Maize), the unit water requirement (UWR) and water demand (WD) considering the irrigation efficiency, irrigation time and irrigation area were estimated to be $0.00122m^3/s/ha$ and $0.0122m^3/s$ respectively. For the water availability assessment, the runoff of Natama scheme was calculated by specific yield method. The water availability was evaluated through reviewed differences of discharge between $Q80_{intake}$ and Total WD, and the irrigation water can be supplied sufficiently in the existing 10ha of Natama scheme. As a result of reviewing the extensibility of irrigable area, total WD of scheme is $0.02313m^3/s$, and $Q80_{intake}$ is $0.02387m^3/s$ ($Q80_{intake}$ > Total WD). Therefore, Natama scheme can be extended from 10 ha to 17 ha in the dry season in consideration of the $Q80_{intake}$.

• Asian-Australasian Journal of Animal Sciences
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• 제33권11호
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• pp.1866-1872
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• 2020

Objective: The objective of the present experiment was to construct self-draining beds to keep surface bedding materials clean and dry for beef cattle comfort in a temperate climate. Methods: In Experiment 1, a self-draining bed was covered with sand at depths of 10 cm (S-10a), 15 cm (S-15), and 20 cm (S-20) respectively. In Experiment 2, self-draining beds of different sizes were covered with 10 cm of sand (S-10b) and wood shavings (WS) at depths of 15 cm and 20 cm (WS-15 and WS-20). Fifteen cattle were engaged to evaluate the comfort of self-draining beds covered with different bedding materials. Results: No cattle lay in the feed alley and cattle spent more time lying on S-10a than S-15 or S-20 in Experiment 1 (p<0.01). No difference in lying time was detected between S-15 and S-20 (p>0.05). In Experiment 2, no cattle selected the feed alley as the lying area. Cattle preferred WS-15 as the lying area and time spent lying on WS-20 was slightly higher than on S-10b (p<0.05). Feces weight was higher in the feed alley than in the different bedding areas in both Experiments 1 and 2 (p<0.01). Conclusion: Sand-bedding depth at 10 cm and WSs at 15 cm above the self-draining bed can provide for the lying comfort of beef cattle. Design of a special feed alley to hold most of the feces to keep bedding materials clean and dry is desirable for organic beef cattle in a loose barn.

• 한국지형학회지
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• 제24권2호
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• pp.65-78
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• 2017

In this study, stable carbon isotopic analysis (22 specimens) and magnetic susceptibility analysis (23 specimens) were conducted out on the specimens collected from two points (trench DT1, DT2) in the floodplain of Jemincheon(hereinafter the Jemin plain) to reconstruct the Holocene Environments (Period I, Period II, Period III) of the Jemin plain in Gongju, Chungnam. The results were as follows: In Period I (approximately 7,480~4,940 yrs B.P.) and especially around 7,480~7,320 yrs B.P., it was cool-dry and there were two minor climate fluctuations. This period received a continuous flow of sediments, rather than massive amounts of sediments due to abrupt flooding, and therefore, there was almost no soilization process. Period II(approximately 4,940~2,600 yrs B.P.) was also relatively cool-dry. However, in Period II b, unlike I, the minor climate fluctuations were less pronounced. In this period, flooding and desiccation repeated, inducing soilization processes especially around 3,160 yrs B.P. In Stage III (~360 yrs B.P.), it was warm and humid compared to II b. However, in III a, there was no inflow of sediments due to irregular flooding, and in fact, soilization process was more manifested than during II b due to the impact of the desiccation environment. However, there were some mass movements from Bonghwang Mt. (a.s.l. 147m) caused by heavy rains and typhoon during III b (approximately 360 yrs B.P.), thus moving a large amount of debris (i.e. gravel), which resulted in sedimentation.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.519-519
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• 2016

Upper Chenab Canal (UCC) is a non-perennial canal in Punjab Province of Pakistan which provides irrigation water only in summer season. Winter and summer are two distinct cropping season with an average rainfall of about 161 mm and 700 mm respectively. Wheat-rice is common crop rotation being followed in the UCC command area. During winter season, groundwater and rainfall are the main sources of irrigation while canal and ground water is used to fulfil the crop water requirements (CWR) during summer. The objective of current study is to estimate how the irrigation water requirements (IWR) of the two crops are going to change under different conditions of temperature and rainfall. For this purpose, 12 different climatic scenarios were designed by combining the assumptions of three levels of temperature increase under dry, normal and wet conditions of rainfall. Weather records of 13 years (2000-2012) were obtained from PMD (Pakistan Meteorological Department) and CROPWAT model was used to simulate the IWR of the crops under normal and scenarios based climatic conditions. Both crops showed a maximum increase in CWR for temperature rise of $+2^{\circ}C$ i.e. 8.69% and 6% as compared to average. Maximum increment (4.1% and 17.51% respectively) in IWR for both wheat and rice was recorded when temperature rise of $+2^{\circ}C$ is coupled with dry rainfall conditions. March & April during winter and August & September during summer were the months with maximum irrigation requirements. Analysis also showed that no irrigation is needed for rice crop during May and June because of enough rainfall in this area.

• 한국기후변화학회지
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• 제2권2호
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• pp.107-113
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• 2011

본 연구에서는 하동화력 0.5 MW 건식 이산화탄소 포집 공정에 적용하고 있는 Potassium 계열 흡수제의 성능 개선을 위한 실험 결과를 기술하였다. 먼저, 마그네타이트와 산화구리를 additive로 적용한 흡수제 2종을 각각 분무건조기를 이용하여 제조한 흡수제의 재생성을 포함한 물성을 평가하였다. 그 결과, 마그네타이트를 적용한 흡수제의 내마모도가 상대적으로 우수한 특성을 나타내었다. 두 번째는, 마그네타이트를 적용한 개량형 Potassium계 흡수제의 연속적인 흡수/재생 특성을 파악하기 위하여 Multi cycle TGA 반응성 평가를 수행하였다. 그 결과, 2nd cycle 이후에도 5.5 wt% 이상의 $CO_2$ 흡수능을 유지하였으며, 내마모도 값도 0.5 정도로 아주 우수하였다. 마지막으로, 공정상의 재생 온도를 낮출 수 있는 조성 선정을 위하여 supporter의 특성이 다른 흡수제의 특성을 고찰하였다. 그 결과, 염기성 지지체를 적용한 KMO 흡수제의 흡수능이 7.2 wt%로 높게 나타났다.

• 한국수자원학회논문집
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• 제46권11호
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• pp.1089-1101
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• 2013

본 논문에서는 미래 극한기후의 변화를 확인하고자 지역기후모형을 이용하여, STARDEX에서 제시한 극한지수를 계산하고 경향성 분석을 통해 미래 극한기후의 지속성과 공간적 분포의 변화양상을 파악하였다. 강수관련 극한지수를 분석한 결과, 수도권과 경기도, 강원도 영동지역, 남해안 지역에서 증가경향성이 확인되었고, 중부 내륙지역에서는 감소경향성이 전망되었다. 기온관련 극한지수를 분석한 결과 기후변화로 인해 미래 우리나라의 평균 기온이 현재보다 증가하는 것을 알 수 있었다. 강수관련 극한지수 중 집중호우 한계점은 경향성에 대한 기울기 값이 서귀포에서 0.229, 지속기간 5일 최대 강수량은 서귀포에서 5.692, 최대 건조지속기간은 속초에서 0.099로 확인되었다. 기온관련 극한지수 중 Hotdays 한계점의 경향성에 대한 기울기 값은 인천에서 0.077, 최대혹서기기간은 울진에서 0.162, Coldnight 한계점은 인제에서 0.075, 동결일수는 통영에서 -0.193으로 확인되었다.

• 한국수자원학회논문집
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• 제55권11호
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• pp.877-886
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• 2022

본 연구는 상사호(주암조절지)의 유량과 수질이 향후 기후변화에 따라 어떻게 변화하며 어떠한 대책이 필요한지에 대한 분석과 관리 대책을 수립하는 것을 지원하고자 수행되었다. 유역의 변화를 예측하기 위하여 HSPF (Hydrological Simulation Program-Fortran) 와 호 내의 수질 예측하기 위해 AEM3D (Aquatic Ecosystem Model)를 연계하여 사용하였다. 기후변화 조건은 IPCC (Intergovernmental Panel on Climate Change)에 따른 AR5(5th Assessment Report)의 RCP (Representative Concentration Pathways) 4.5와 RCP 8.5 시나리오를 사용하였다. 기후변화 시나리오는 기상청에 의해 상사호 유역에 대한 상세화된 자료를 사용하였고, 2012년~2021년의 10년간의 기간에 대해 보정 및 검증 하고, 미래 상황의 예측을 위해 현재, 2025년~2036년, 2045년~2056년 그리고 2075년~2086년의 기간으로 구분하고 또한 연도별로 6월부터 8월까지의 여름철과 12월부터 2월까지의 겨울철에 대해 구분하여 분석하였다. 전체 모의 기간에 대한 상사호 유역의 유량은 산술 평균으로는 RCP 4.5보다 RCP 8.5 가 큰 것으로 나타났으며 TN, TP 또한 RCP 4.5에서 높은 경향을 나타내었다. 그러나 RCP 8.5에서 갈수기에는 오염물질의 유출이 감소하고, 여름철에는 오염물질의 유출이 증가하여 연간 오염물질 유출량이 홍수기에 집중되는 특성을 나타내었으며 이에 따른 대책이 필요할 것으로 분석된다.