• 대한수학회논문집
• /
• 제10권2호
• /
• pp.393-400
• /
• 1995

We define a group extension and characterized some properties of the group extension. In particular, we show that the quotient map $\nu$ is a continuous group isomorphism and subgroup $H_1(H_2)$ is normal in $G_1(G_2)$.

• 한국토양비료학회지
• /
• 제47권4호
• /
• pp.262-268
• /
• 2014

The management of soil chemical properties is very important to sustainable agriculture of many horticultural crops, including cucumber. This study was conducted to find the optimal soil properties of environmentally friendly agriculture in controlled horticulture. Soil chemical properties of 267 samples were collected from soil in Chungnam Province. The average of pH, EC, OM, available $P_2O_5$, exchangeable K, Ca, and Mg was 6.1, $5.38dS\;m^{-1}$, $34g\;kg^{-1}$, $1,321mg\;kg^{-1}$, $1.50cmol_c\;kg{-1}$, $10.3cmol_c\;kg{-1}$, and $3.4cmol_c\;kg{-1}$, respectively. The organic matter content in silty clay loam was significantly higher than in the other soil textures, whereas the pH, EC, exchangeable K, and Mg in loamy fine sand showed significantly lower among soil textures. The EC value and exchangeable Mg concentration were highest in mountain foot-slope soils. The frequency distribution within optimum range of soil chemical properties was 26.2%, 30.3%, 2.3%, 3.8%, 3.4%, and 6.7% for pH, OM, available $P_2O_5$, exchangeable K, Ca, and Mg, respectively. Especially, excessive portion of available $P_2O_5$ and exchangeable Ca were 94.0% and 94.4%, respectively. The EC value and organic matter content of soil samples were positive correlation with all chemical properties except soil pH. In principle component analysis of chemical properties in soil samples, the percentage of variance explained by PC 1 was 52.2%, while PC 2 explained 21.3% of the variance, for a cumulative total of 73.5%. In conclusion, these results are considered to improve soil nutrient management for sustainable controlled horticulture.

• 한국안전학회지
• /
• 제17권2호
• /
• pp.52-57
• /
• 2002

In this study. stress-strain relationships were investigated by performing the confined extension tests for seven types of geosynthetics such as geotextiles, composite geosynthetics and geogrids. A comparison was made between unconfined and confined moduli for each geosynthetic material to quantify the soil confinement effect on stress-strain properties. A comparison was also made between the increase of moduli at the same strain level with the types of the geosynthetics to demonstrate the different stress-strain responses. Based on the result of the extension tests, the higher the confining stress, the larger the secant modulus of geosynthetics. The secant modulus at 5% strain is twice as much as that of 10% strain, especially there is a noticeable increasing of secant modulus for the two nonwoven geotextiles.

• International Journal of Concrete Structures and Materials
• /
• 제19권1E호
• /
• pp.25-32
• /
• 2007

The fracture energy evaluated from the previous experimental results can be simulated by using the modified singular fracture process zone (S-FPZ) model. The fracture model has two fracture properties of strain energy release rate for crack extension and crack close stress versus crack width relationship $f_{ccs}(w)$ for fracture process zone (FPZ) development. The $f_{ccs}(w)$ relationship is not sensitive to specimen geometry and crack velocity. The fracture energy rate in the FPZ increases linearly with crack extension until the FPZ is fully developed. The fracture criterion of the strain energy release rate depends on specimen geometry and crack velocity as a function of crack extension. The behaviors of micro-cracking, micro-crack localization and full development of the FPZ in concrete can be explained theoretically with the variation of strain energy release rate with crack extension.

• International Journal of Aeronautical and Space Sciences
• /
• 제4권2호
• /
• pp.9-16
• /
• 2003

Piezoelectric materials are widely used to construct smart or adaptive structures. Although extensive efforts have been devoted to the analysis of piezoelectric materials in recent years, most researches have been conducted by assuming that the material properties are fixed and have no uncertainties. Intrinsically, material properties have a certain amount of scatter and such uncertainties can affect the performance of component. In this paper, the convex modeling is used to consider such uncertainties in calculating the crack extension force of piezoelectric material and the results are compared with the one obtained via the Monte Carlo simulation. Numerical results show that crack extension forces increase when uncertainties considered, which indicates that such uncertainties should not be ignored for reliable lifetime prediction. Also, the results obtained by the convex modeling and the Monte Carlo simulation show good agreement, which demonstrates the effectiveness of the convex modeling.

• 한국수학교육학회지시리즈A:수학교육
• /
• 제22권3호
• /
• pp.27-31
• /
• 1984

In this paper we summarize the characteristic properties of the nuclear space, and then try to establish the relation between Hopf's extension theorem and nuclear space on $\sigma$-Hilbert space.

• 한국약용작물학회:학술대회논문집
• /
• 한국약용작물학회 2011년도 춘계학술발표회
• /
• pp.426-427
• /
• 2011

• 한국약용작물학회지
• /
• 제9권1호
• /
• pp.76-82
• /
• 2001

고추냉이 물재배에서 토양의 배지조성이 고추냉이의 생육 및 수량에 미치는 영향을 구명하기 위해 시험한 결과 토양의 입경 조성은 일본에 비하여 마사토, 강모래에서는 2mm 이상의 자갈 함량이 적었고 조사의 분포가 많았다. 토양경도는 마사토와 강모래에서 상층은 $11.3{\sim}12.9$, 하층은 $12.5{\sim}15.1$ 사이에 분포하였으나, 난석에서 상층은 $5.5{\sim}5.8$, 하층은 $6.2{\sim}7.0$ 사이에 분포하여 난석의 경도가 가장 낮았다. 근계 분포는 경도가 낮은 난석에서는 좁고 깊게 분포하였으나, 경도가 높은 마사토, 강모래에서는 넓고 말게 분포하였다. 근경중은 난석에서 입수구 쪽은 766kg/10a, 퇴수구 쪽은 649kg/10a, 마사토에서 입수구 쪽은 338kg/10a, 퇴수구쪽은 334kg/10a, 강모래에서 입수구 쪽은 451kg/10a, 퇴수구 쪽은 332k9/10a로 난석 대비 입수구 쪽은 마사토 44%, 강모래 59%, 퇴수구 쪽은 마사토, 강모래 각각 51% 수준이었다.

• 한국토양비료학회지
• /
• 제48권5호
• /
• pp.492-498
• /
• 2015

The long-term changes in the soil properties are closely related to the policy direction and the national program for the soil management. In this study, chemical properties of paddy soils in Jeonnam province were investigated at four-year interval since 1999 and the factors affecting change of chemical properties were analyzed in relation to the soil management policies. Chemical fertilizers supplied to Jeonnam province reduced by 57% in 2013 as compared with 1999, and the ratio of Jeonnam province to the national fertilizer supply gradually decreased to 14.1% in 2013 from 17.6% in 1999 due to national policies to reduce use of chemical fertilizers in the 2000s. In the chemical analysis of paddy soils in Jeonnam province, pH value tended to increase gradually within the optimal range. Available phosphate and exchangeable potassium content were always higher than the optimal range and showed no significant difference since 1999. Organic matter, exchangeable calcium and available silicate content were found to be lower than average content in the whole country as well optimal range for rice cultivation in 1999, but were higher than average content in the whole country and optimal range in 2011 because of faster rate of increase in Jeonnam province than the other region since the mid-2000s. The cause of increase in organic matter, exchangeable calcium and available silicate contents is considered to be the increased use of green manure crops and by-products fertilizer as an alternatives for conventional application of chemical fertilizers and soil amendment such as silicate fertilizer for agronomic control of the disease and insect pest in rice cultivation of environmentally-friendly agriculture.

• 한국식품저장유통학회지
• /
• 제31권4호
• /
• pp.527-540
• /
• 2024

Whole wheat flour is produced by grinding wheat grains and blending each milling fraction such as wheat bran and white flour with no specific standard for the proportions. An exploration on classifying and utilizing Korean whole wheat flour is required to increase the practical use of many different types of Korean wheat flour products. This study aimed to examine factors for categorization and processability of Korean whole wheat flour by investigating quality characteristics and bread-making properties of Korean hard wheat flour samples produced with different levels of wheat bran (0% as control, 5%, 10%, 15%, 20%, and whole grain wheat flour). The ash content of flour samples was divided into six gradational categories, which could be suggested as classification criteria for Korean whole wheat flour. The main parameters of dough and gelatinization properties of the flour samples exhibited downtrends, but nutritional constituents demonstrated uptrends with increasing bran addition level. The bread specific volume, hardness, chewiness, and brittleness of bread had strong correlations with dough stability and pasting parameters, which could be presented as significant factors for predicting bread-making properties of Korean whole wheat flour.