• 한국농림기상학회지
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• 제6권1호
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• pp.61-69
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• 2004

A long-term growth simulation was performed at 99 land units in Yeoncheon county to test the potential adaptability of each land unit for growing soybean cultivars. The land units for soybean cultivation(CZU), each represented by a geographically referenced land patch, were selected based on land use, soil characteristics, and minimum arable land area. Monthly climatic normals for daily maximum and minimum temperature, precipitation, number of rain days and solar radiation were extracted for each CZU from digital climate models(DCM). The DCM grid cells falling within a same CZU were aggregated to make spatially explicit climatic normals relevant to the CZU. A daily weather dataset for 30 years was randomly generated from the monthly climatic normals of each CZU. Growth and development parameters of CROPGRO-soybean model suitable for 2 domestic soybean cultivars were derived from long-term field observations. Three foreign cultivars with well established parameters were also added to this study, representing maturity groups 3, 4, and 5. Each treatment was simulated with the randomly generated 30 years' daily weather data(from planting to physiological maturity) for 99 land units in Yeoncheon to simulate the growth and yield responses to the inter-annual climate variation. The same model was run with input data from the Crop Experiment Station in Suwon to obtain a 30 year normal performance of each cultivar, which was used as a "reference" for evaluation. Results were analyzed with respect to spatial and temporal variation in yield and maturity, and used to evaluate the suitability of each land unit for growing a specific cultivar. A computer program(MAPSOY) was written to help utilize the results in a decision-making procedure for agrotechnology transfer. transfer.

• 한국수자원학회논문집
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• 제38권2호
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• pp.97-110
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• 2005

본 연구에서는 기존댐 재개발에 따른 댐 재개발 최적 규모 선택을 위한 방법론을 제시하고자 한다. 최적규모의 분석을 위한 과정은 다음과 같다. 강우량은 비동질성 Markov 모형으로 모의 발생하여 비교적 실제 구조에 가깝도록 설계된 토양함수 모형(Sacramento Soil Moisture Accounting Model, SAC-SMA)과 HEC-1의 Kinematic wave 하도추적 모형을 결합하여 만든 미 기상국의 NWS-PC 모형을 이용하여 유입량으로 변환하였다. 유입량은 저수지 모의운영을 통하여 저수지의규모를 결정하였다. 괴산댐을 대상으로 Hashimoto등 (1982)이 제시한 신뢰성 기준을 바탕으로 재개발 적정규모에 대한 신뢰성 분석을 실시하였으며 대략 155EL.M가 최적 수위로 판단되었으며 댐규모를 판단하기 위한 보조수단으로 이용이 가능하리라 사료된다.

• 한국작물학회지
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• 제53권1호
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• pp.8-14
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• 2008

Ammonia ($NH_3$) volatilization from a silty clay loam paddy soil applied with non, straight urea, and coated urea, respectively, under transplanting in Milyang, Korea from 2002 and 2003 was simulated by a Water and Nitrogen Management Model (WNMM). Based on the data from the in-situ measurements, $NH_3$ volatilization during the rice growth was 6.04% and 1.46% of the applied nitrogen (N) from straight urea and coated urea, respectively. The bulk aerodynamic approach in WNMM satisfactorily predicted the difference in $NH_3$ loss during the given rice growing seasons from the two urea fertilizers. $R^2$ for the correlation between the predicted and observed NH3 loss during the calibration year (2002) was 0.53 less than 0.68 of the application year (2003). This difference could be due to the weather condition such as heavy rainfall and temperature during the calibration year.

• 한국지반공학회논문집
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• 제20권2호
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• pp.5-13
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• 2004

기존의 흙을 사용하여 건설된 철도 노반은 반복적인 교통하중의 증가, 열차속도의 향상, 노반상으로의 지하수의 유입, 노반의 배수능력 저하 등의 이유로 인해 시간경과에 따라 쉽게 그 기능을 상실할 수 있다. 본 연구에서는 실대형시험과 수치해석을 수행함으로씨 철도노반으로서의 쇄석강화노반의 성능을 평가하였다. 쇄석강화노반의 탄$.$소성 연직변위는 모사열차하중의 재하횟수에 관계없이 일반 흙노반에 비해 작은 응답특성을 보였으며, 동일한 노반 부설두께에서는 노반반력계수의 증가에 따라 감소하며, 동일한 강성인 경우 노반 부설두께 증가에 따라 감소하는 경향을 보였다. 하지만, 쇄석강화노반의 부설두께에 비해 노반의 강성이 궤도에 발생하는 전체 소성 연직변위에 더욱 큰 영향을 미치는 것으로 평가되었다.

• Journal of Plant Biology
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• 제37권3호
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• pp.309-316
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• 1994

To make regional comparisons of water status of pitch pine, the temporal changes of water status in pitch pine were investigated at different areas; urban Seoul (heavily polluted area), surburb of Seoul (lightly polluted area), and rural area (control). The effects of air pollutants, acid rain and chemical properties of soil on water deficit in pitch pine were also investiaged. Water content of needles growing at polluted areas were usually lower than that at unpolluted area. Water saturation deficit of needles growing at polluted areas were usually higher than that at unpolluted area especially in dry season. These results indicated that water in needles growing at polluted areas were usually more deficient than that at unpolluted area, and were more deficient in April than other months. At polluted areas, the older the needles were, the more quickly transpirated the water in the needle was. At unpolluted areas, however, water in old needles was not so quickly transpirated as those at polluted areas. Water potential of needles of pitch pine seedlings treated with simulated acid rain (SAR) of pH 3.5 decreased more quickly than that of needles treated with SAR of pH 5.6. Loss of water through epicuticular layer was greater in the following order: magnesium deficiency＋100 $\mu$M aluminium>100$\mu$M aluminium>magnesium deficiency>control. In addition to Mg deficiency and Al toxicity, growth decline of pitch pine widely occurring in polluated Seoul could to a large extent be due to cuticle degredation and abnormal vertical distribution of fine roots, which lead to water stress, particularly in dry seasons.

• 한국수자원학회논문집
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• 제37권9호
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• pp.737-744
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• 2004

본 연구에서는 산림식생에 따른 장기적인 측면에서의 유역 물수지 영향을 살펴보기 위하여 보청천 유역을 대상유역으로 선정하고, 준분포형 매개변수 모형인 SWAT 모형을 적용하여, 침엽수와 활엽수에 따른 증발산, 지표유출, 중간유출, 기저유출, 총 유출의 차이를 검토하였다. 먼저 SWAT 모형내 식생 생장 알고리즘을 수정하여 연중 일정한 엽면적지수를 갖는 국내 침엽수림의 생장 특성을 반영할 수 있도록 하였으며, 대상유역을 하나의 토지피복을 갖는 가상의 유역으로 설정한 후, 수정된 SWAT 모형을 적용하여 각 물수지 요소 변화를 모의한 결과, 침엽수가 활엽수에 비해 증발산 증가 및 유출 감소에 더 영향을 미치는 것으로 나타났다. 그러나, 보다 정량적인 규명과 유출모형의 불확실성을 보완하기 위해서는 수종 외에 수령, 식재밀도, 식재위치, 토양특성자료 등 다양한 조건이 충분히 고려되어야 할 것이다.

• Applied Biological Chemistry
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• 제26권1호
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• pp.53-57
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• 1983

이종(二種)의 토양(土壤)을 가지고 논과 유사한 상태(狀態)로 만들어 butachlor를 일정기간(一定其間) 배양시(培養時) 모든 경우 주분해산물(主分解産物)로 2,6-diethyl-N-(butoxymethyl) acetanilide와 신분해산물(新分解産物) C를, 그리고 경우에 따라서는 비교적(比較的) 소량(少量)의 신분해산물(新分解産物) 8-ethyl-2-hydroxy-N-(butoxymethyl) 3,4-dihydroguinoline을 생성(生成)하였다. 토양미산물(土壤微産物)의 작용(作用)으로 추측(推測)되는 이 분해(分解)는 어느 정도 배양기간에 비 해하여 진행(進行)되었다. 전번 연구의 혐기적 배양시에는 2,6-diethyl-N-(butoxymethyl) acetanilide가 주분해산물(主分解産物)인 반면 이번 경우에는 m/z a91의 물질(物質)이 주분해산물(主分解産物)이었다. 그리고 Mass Spectrum의 Fragmentation Pattern에 의(依)하여 이들 신분해산물(新分解産物)의 화학구조(化學構造)를 구명(究明)하고 가능(可能)한 생성경로(生成經路)를 추정(推定)하였다.

• Journal of Radiation Protection and Research
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• 제29권2호
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• pp.117-127
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• 2004

핵종 누출 사고시 논으로의 핵종 이동 평가를 위한 동적격실모델을 개발하였다. 개발된 모델에는 벼 재배에 필수적인 관개수를 고려하여 표면수 격실과 줄기기부흡수 개념을 도입하였고, 이식 전 쟁기질과 관개담수에 의한 토양 혼합을 고려하였으며, 벼 성장에 따른 뿌리흡수상수, 줄기기부흡수상수의 변화를 생체량의 함수로 모델링하였다. 모델의 타당성 조사를 위해 고리, 영광 및 울진 원자력 발전소 주변 지역에서 채취한 논 토양으로 벼를 재배하면서 벼 생육단계별로 수행된 $^{137}Cs$ 모의 침적 실험 해석에 모델을 적용하였다. 모델은 대체적으로 한 승수 내에서 실험 결과와 잘 일치하였다.

• 농업과학연구
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• 제43권3호
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• pp.441-449
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• 2016

Agricultural tractors are designed using the empirical method due to the difficulty of measuring precise load cycles under various working conditions and soil types. Especially, directly drives various tractor implements, the power take off (PTO) gear. Therefore, alternative design methods using gear design software are needed for the optimal design of tractors. The objective of this study is to simulate fatigue life of the PTO gear according to the operating point of the tractor engine. The PTO gear was made with SCr415 alloy steel with carburizing and quenching treatments. The fatigue life of the PTO gear was simulated by using bending and contact stress according to the torque of the load levels. The PTO gear simulation was conducted by the KISSsoft commercial software for gear analysis. Bending and contact stress were calculated by the ISO 6336:2006 Method A and B. The simulation of fatigue life was calculated by the Miner's cumulative damage law. The total fatigue life of tractors can be estimated to 3,420 hours; thus, 3,420 hours of fatigue life were used in the simulation of the PTO gear of tractors. The main simulation results showed that the maximum fatigue life of the PTO gear was infinite fatigue life at maximum engine power. Minimum fatigue life of the PTO gear was 19.61 hours at 70% of the maximum engine power. Fatigue life of the PTO gear changed according to load of tractor. Therefore, tractor work data is needed for optimal design of the PTO gear.

• Earthquakes and Structures
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• 제9권3호
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• pp.603-623
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• 2015

The scale and nature of the recent earthquakes in the world and the related earthquake disaster index coerce the concerned community to become anxious about it. Therefore, it is crucial that seismic lateral load effect will be appropriately considered in structural design. Application of seismic isolation system stands as a consistent alternative against this hazard. The objective of the study is to evaluate the structural and economic feasibility of reinforced concrete (RC) buildings with base isolation located in medium risk seismic region. Linear and nonlinear dynamic analyses as well as linear static analysis under site-specific bi-directional seismic excitation have been carried out for both fixed based (FB) and base isolated (BI) buildings in the present study. The superstructure and base of buildings are modeled in a 3D finite element model by consistent mass approach having six degrees of freedom at each node. The floor slabs are simulated as rigid diaphragms. Lead rubber bearing (LRB) and High damping rubber bearing (HDRB) are used as isolation device. Change of structural behaviors and savings in construction costing are evaluated. The study shows that for low to medium rise buildings, isolators can reduce muscular amount of base shears, base moments and floor accelerations for building at soft to medium stiff soil. Allowable higher horizontal displacement induces structural flexibility. Though incorporating isolator increases the outlay, overall structural cost may be reduced. The application of base isolation system confirms a potential to be used as a viable solution in economic building design.