• 터널과지하공간
• /
• 제31권6호
• /
• pp.593-609
• /
• 2021

본 연구에서는 입자기반 개별요소모델(grain-based distinct element model, GBDEM)을 이용하여 결정질 암석 내 포함된 균열의 열-역학적 거동을 평가할 수 있는 수치해석기법을 제시하고 열에 의한 균열의 미끄러짐 거동을 해석하였다. 이는 DECOVALEX-2023 프로젝트 Task G의 일환으로 수행된 벤치마크 모델링 연구로, Task G는 결정질 암반 내 균열의 열-수리-역학적 복합거동을 해석하기 위한 수치해석기법을 개발하는 데에 목표가 있다. 여기에서는 Voronoi diagram을 이용하여 다면체 개별입자의 집합체로서 해석모델을 생성하고, 입자 및 입자간 접촉에서 발생하는 열-역학적 거동을 개별요소프로그램인 3DEC을 통해 해석하였다. 암석 시험편의 탄성거동을 재현하기 위하여 등가연속체 개념을 적용하여 입자와 접촉의 미시물성을 산정하였으며, 균열에 상응하는 접촉에는 Coulomb slip model을 부여하여 인장강도와 전단강도를 갖는 불연속면을 모사하였다. 경계응력과 열응력에 의한 균열의 거동을 수치적으로 모델링하였으며, 경계조건에 따라 균열의 미끄러짐이 발생하는 열-역학적 메커니즘을 정량적으로 분석하였다. 해석 결과, 본 연구에서 제시한 해석모델이 암석 내 열팽창과 열응력의 증가, 균열 응력과 변위, 경계조건의 영향 등을 합리적으로 재현하고 있음을 확인하였다. 본 연구의 해석모델은 Task G에 참여하는 국외 연구팀들과의 의견 교류와 워크숍을 통해 지속적으로 개선하는 한편, 향후 실내실험에 적용하여 타당성을 검증할 예정이다.

• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2000년도 춘계 학술대회지
• /
• pp.412-413
• /
• 2000

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
• /
• pp.371-374
• /
• 2006

To quantify the hydraulic connection between river and aquifer, riverbed leakance values are required to be estimated. Silt, clay, and organic materials are often deposited in rivers resulting in the streambed having a lower hydraulic conductivity than the underlying alluvial aquifer The riverbed hydraulic conductivities are measured through vertical and oblique permeameter test. Anisotropic and heterogeneous properties of riverbed hydraulic conductivity were identified. Grain size analysis and flood wave response technique were checked along with the permeameter test for the riverbed hydraulic conductivity.

• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2001년도 춘계 학술대회지
• /
• pp.70-71
• /
• 2001

• 한국세라믹학회지
• /
• 제44권12호
• /
• pp.655-659
• /
• 2007

Zirconia polycrystals co-doped with x mol% CaO and (10-x) mol% $Y_2O_3$ were prepared by solid state reaction method. The compositions were chosen for nominally the same oxygen vacancy concentration of 5 mol%. X-ray diffraction patterns indicated the formation of cubic zirconia by heat treatment at $1600^{\circ}C$. Impedance spectroscopy was applied to deconvolute the bulk and grain boundary response. Electrical conductivity was measured using the complex impedance technique from 516 to 874 K in air. Maximum conductivity was exhibited by the composition with equal amounts of CaO and $Y_2O_3$, which may be ascribed to the smaller degree of defect-interactions in that composition due to the competition of different ordering schemes between the two systems. When compared to the composition containing $Y_2O_3$ only, co-doping of CaO increases the grain boundary resistance considerably. The activation energy of grain and grain boundary conductivity was 1.1 eV and 1.2 eV, respectively, with no appreciable dependence on dopant compositions.

• 한국작물학회지
• /
• 제51권7호
• /
• pp.618-623
• /
• 2006

쌀의 외관 기호도에 영향을 미치는 몇가지 관련 특성을 검토하고 이들의 상호관계를 구명함으로써 쌀 외관품질의 등급화를 위한 기초자료를 확보하고자 국내에서 주로 재배되고 있는 자포니카 44품종 쌀에 대한 외관기호도와 관련 특성을 조사 및 평가하여 얻어진 결과는 다음과 같다. 1. 쌀의 색기호도는 외관품질(r=-0.897) 및 적색도(r=-0.893)와 유의한 부의 상관을 나타내었다. 2. 외관품질(적색도${\times}$황색도)은 색에 의한 쌀 외관의 등급화에 유용하게 활용될 수 있을 것으로 판단되었다. 3. 쌀의 모양에 대한 기호도는 입폭(r=0.527)과 입의 크기(r=0.454)가 유의한 정 상관을 나타내었다. 4. 쌀의 외관에 대한 기호도의 군집분석결과 5개의 그룹으로 분류되었으며 그룹별 품질은 외관품질, 입폭 및 입크기 등에 의해 품질등급화가 가능할 것으로 판단되었다.

• The Plant Pathology Journal
• /
• 제37권5호
• /
• pp.455-464
• /
• 2021

Forty-eight spring barley genotypes were evaluated for deoxynivalenol (DON) concentration under natural infection across 5 years at Harrington, Prince Edward Island. These genotypes were also evaluated for Fusarium head blight (FHB) severity and DON concentration under field nurseries with artificial inoculation of Fusarium graminearum by the grain spawn method across 2 years at Ottawa, Ontario, and one year at Hangzhou, China. Additionally, these genotypes were also evaluated for FHB severity under greenhouse conditions with artificial inoculation of F. graminearum by conidial suspension spray method across 3 years at Ottawa, Ontario. The objective of the study was to investigate if reactions of barley genotypes to artificial FHB inoculation correlate with reactions to natural FHB infection. DON concentration under natural infection was positively correlated with DON concentration (r = 0.47, P < 0.01) and FHB incidence (r = 0.56, P < 0.01) in the artificially inoculated nursery with grain spawn method. Therefore, the grain spawn method can be used to effectively screen for low DON. FHB severity, generated from greenhouse spray, however, was not correlated with DON concentration (r = 0.12, P > 0.05) under natural infection and it was not correlated with DON concentration (r = -0.23, P > 0.05) and FHB incidence (r = 0.19, P > 0.05) in the artificially inoculated nursery with grain spawn method. FHB severity, DON concentration, and yield were affected by year, genotype, and the genotype × year interaction. The effectiveness of greenhouse spray inoculation for indirect selection for low DON concentration requires further studies. Nine of the 48 genotypes were found to contain low DON under natural infection. Island barley had low DON and also had high yield.

• 한국재료학회지
• /
• 제28권12호
• /
• pp.702-708
• /
• 2018

This study deals with the effect of microstructure factors on the strain aging properties of API X70 pipeline steels with different microstructure fractions and grain sizes. The grain size and microstructure fraction of the API pipeline steels are analyzed by optical and scanning electron microscopy and electron backscatter diffraction analysis. Tensile tests before and after 1 % pre-strain and thermal aging treatment are conducted to simulate pipe forming and coating processes. All the steels are composed mostly of polygonal ferrite, acicular ferrite, granular bainite, and bainitic ferrite. After 1 % pre-strain and thermal aging treatment, the tensile test results reveal that yield strength, tensile strength and yield ratio increase, while uniform elongation decreases with an increasing thermal aging temperature. The increment of yield and tensile strengths are affected by the fraction of bainitic ferrite with high dislocation density because the mobility of dislocations is inhibited by interaction between interstitial atoms and dislocations in bainitic ferrite. On the other hand, the variation of yield ratio and uniform elongation is the smallest in the steel with the largest grain size because of the decrease in the grain boundary area for dislocation pile-ups and the presence of many dislocations inside large grains after 1 % pre-strain.

• 한국작물학회지
• /
• 제48권2호
• /
• pp.65-67
• /
• 2003

This study was conducted to analyze the effects of genotypes, environments and interaction of G$\times$E on yields of sesame grown in seven different environments by AMMI analysis. Environments accounted for the largest (91 %) proportion of the sums of squares, followed by G$\times$E (8%) and genotypes (1%) Therefore, G$\times$E effects are theoretically eight times as important as G effects. G2 (Yanghukkae) has the largest IPCAI scores indicating higher G$\times$E interaction. G3 (Suwon 171) was near zero score of IPCAI suggesting higher stability than others in yield component. Most of environments except for Iksan area shows different G$\times$E effects by years, which means Iksan is optimal area for multi-environmental adaptation evaluation in sesame breeding programs. According to this experiment, it is concluded that maximization of grain yield through environments can be achieved by specific genotypes in specific environments.

• 대한기계학회논문집A
• /
• 제28권4호
• /
• pp.453-459
• /
• 2004

25Cr-20Ni series strainless steels have an excellent high temperature strength high oxidation and high corrosion resistance. However, further improvement can be expected of creep strength by work hardening prior creep. In the present study, the effect of prestraining at room temperature on the creep behavior of a Class M(STS310S) and a Class A(STS310J1TB) alloy containing precipitates have been examined. Prestaining was carried out at room temperature and range of prestrain was 0.5-2.5 % at STS310J1TB and 2.0-7.0% at STS310S. Creep behavior and creep rate of pre-strained specimens were compared with that of virgin specimens. Room temperature prestraining produced the creep life that is longer than that of a virgin specimen both for STS310J1TB and STS310S when creep test was carried out at the temperature lower than recrystallization temperature. The reason for this improvement of creep life was ascribable to the interaction between dislocations and precipitates in addition to the dislocation-dislocation interaction in STS310J1TB and the dislocation-dislocation interaction in STS310S. The beneficial effect of prestraining in STS310J1TB was larger than that of STS310S.