• 한국토양비료학회지
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• 제28권3호
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• pp.218-226
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• 1995

복숭아 묘목으로 부터 채취한 근권 및 그 주변 토양을 이용하여 $NH_4-K$와 $NH_4-Ca$ 치환 현상을 조사하였으며 이 결과를 토양중 암모니움 등 양이온의 이동과 분포의 모델화에 적용할 수 있는 치환식을 찾고자 했다. 토양시료를 $NH_4Cl$, KCl과 $CaCl_2$ 용액으로 평형에 도달시킨 후 $Sr(NO_3)_2$ 용액으로 추출하여 평형상태에서의 치환태 양이온 조성을 구하였다. Vanselow, Gapon 그리고 kerr의 식은 $NH_4-K$와 $NH_4-Ca$ 치환 현상을 적절히 기술할 수 없었으나 치환태 양이온 농도에 임의의 지수를 갖는 다음과 같은 경험식이 매우 적절한 것으로 나타났다. ${\frac{\alpha_i^m}{a_j^n}}=K{\frac{(iX)^{mPi}}{(jX)^{nPj}}}$ 이 식에서 ${\alpha}i$와 ${\alpha}j$는 원자가가 m과 n인 양이온 i 및 j의 용액 중 activity이며(iX)와 (jX)는 치환태양이온 i와 j의 농도이다. 치환태 양이온의 농도 단위로는 몰 분율 또는 당량 분율을 사용할 수 있다. 임의상수 $P_i$와 $P_j$ 그리고 분배상수 K는 이 식의 대수형을 이용하여 다중 회귀 방법으로 구할 수 있다.

• 한국식품영양과학회지
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• 제44권4호
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• pp.540-548
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• 2015

본 연구에서는 김치에서 분리한 Bacillus subtilis KMKW4를 이용하여 백미 및 아마란스를 영양원으로 발효하였으며 발효물의 배양 특성과 항산화 활성 및 생리활성을 조사하였다. 백미와 아마란스의 비율별로 제조한 발효물 중 아마란스 20%가 첨가된 R80의 생균수가 가장 높았고 pH 또한 낮아 발효가 잘 진행되었음을 확인하였다. 발효물의 amylase 활성을 측정한 결과 R100, R90, R80, R70 중 R80에서 48시간 배양 시 57.77 unit/mL로 가장 높아 R80을 곡류 효소 함유 제품 개발을 위한 혼합조건으로 선정하였다. 발효물의 동결건조분말에 대한 amylase 활성도 발효물과 동일하게 48시간에서 가장 높게 나타나 동결건조 후에도 효소 활성이 유지되는 것을 확인하였다. 발효물 동결건조분말의 유리당 함량은 발효 후 R80에서 maltose는 검출되지 않았으며, glucose는 5,454.2 mg/100 g으로 함량이 증가하였고 R100보다 높음을 확인하였다. 유리아미노산 함량은 R100의 경우 발효 전 664.9 mg/100 g에서 48시간 발효 후 834.2 mg/100 g으로 증가하였으며, R80은 발효 전 868.8 mg/100 g에서 발효 후 1,085.2 mg/100 g으로 증가하였다. 항산화 활성은 발효함에 따라 증가하였으며 R100보다 R80에서 우수하였다. ACE 저해 활성은 발효 전 R100과 R80에서 각각 30.12%와 40.22%로 나타났으며 발효 후에는 각각 59.13%와 78.57%로 나타나 발효가 진행됨에 따라 증가하는 경향을 보였고 R80이 R100보다 더 높은 ACE 저해 활성을 나타내었다. ${\alpha}$-Glucosidase 저해 활성은 모든 실험군에서 발효 전보다 발효 후에 높은 저해 활성을 나타내었으며, R100보다 R80이 우수하여 향후 곡류 효소 함유 식품 제조를 위한 소재로 활용 가능하다고 사료된다.

• 농업과학연구
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• 제14권1호
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• pp.98-133
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• 1987

The mechanical and rheological properties of agricultural materials are important for engineering design and analysis of their mechanical harvesting, handling, transporting and processing systems. Agricultural materials, which composed of structural members and fluids do not react in a purely elastic manner, and their response when subjected to stress and strain is a combination of elastic and viscous behavior so called viscoelastic behavior. Many researchers have conducted studies on the mechanical and rheological properties of the various agricultural products, but a few researcher has studied those properties of rice plant, and also those data are available only for foreign varieties of rice plant. This study are conducted to experimentally determine the mechanical and the rheological properties such as axial compressive strength, tensile strength, bending and shear strength, stress relaxation and creep behavior of rice stems, and grain detachment strength. The rheological models for the rice stem were developed from the test data. The shearing characteristics were examined at some different levels of portion, cross-sectional area, moisture content of rice stem and shearing angle. The results obtained from this study were summarized as follows 1. The mechanical properties of the stems of the J aponica types were greater than those of the Indica ${\times}$ Japonica hybrid in compression, tension, bendingand shearing. 2. The mean value of the compressive force was 80.5 N in the Japonica types and 55.5 N in the Indica ${\times}$ Japonica hybrid which was about 70 percent to that of the Japonica types, and then the value increased progressively at the lower portion of the stems generally. 3. The average tensile force was about 226.6 N in the Japonica types and 123.6 N in the Indica ${\times}$ Japonica hybrid which was about 55 percent to that of the Japonica types. 4. The bending moment was $0.19N{\cdot}m$ in the Japonica types and $0.13N{\cdot}m$ in the Indica ${\times}$ Japonica hybrid which was 68 percent to that of the Japonica types and the bending strength was 7.7 MPa in the Japonica types and 6.5 MPa in the Indica ${\times}$ Japonica hybrid respectively. 5. The shearing force was 141.1 N in Jinju, the Japonica type and 101.4 N in Taebaeg, the Indica ${\times}$ Japonica hybrid which was 72 percent to that of Jinju, and the shearing strength of Taebaeg was 63 percent to that of Jinju. 6. The shearing force and the shearing energy along the stem portion in Jinju increased progressively together at the lower portions, meanwhile in Taebaeg the shearing force showed the maximum value at the intermediate portion and the shearing energy was the greatest at the portion of 21 cm from the ground level, and also the shearing strength and the shearing energy per unit cross-sectional area of the stem were the greater values at the intermediate portion than at any other portions. 7. The shearing force and the shearing energy increased with increase of the cross-sectional area of the rice stem and with decrease of the shearing angie from $90^{\circ}$ to $50^{\circ}$. 8. The shearing forces showed the minimum values of 110 N at Jinju and of 60 N at Taebaeg, the shearing energy at the moisture content decreased about 15 percent point from initial moisture content showed value of 50 mJ in Jinju and of 30 mJ in Taebaeg, respectively. 9. The stress relaxation behavior could be described by the generalized Maxwell model and also the compression creep behavior by Burger's model, respectively in the rice stem. 10. With increase of loading rate, the stress relaxation intensity increased, meanwhile the relaxation time and residual stress decreased. 11. In the compression creep test, the logarithmic creep occured at the stress less than 2.0 MPa and the steady-state creep at the stress larger than 2.0 MPa. 12. The stress level had not a significant effect on the relaxation time, while the relaxation intensity and residual stress increased with increase of the stress level. 13. In the compression creep test of the rice stem, the instantaneous elastic modulus of Burger's model showed the range of 60 to 80 MPa and the viscosities of the free dashpot were very large numerical value which was well explained that the rice stem was viscoelastic material. 14. The tensile detachment forces were about 1.7 to 2.3 N in the Japonica types while about 1.0 to 1.3 N in Indica ${\times}$ Japonica hybrid corresponding to 58 percent of Japonica types, and the bending detachment forces were about 0.6 to 1.1 N corresponding to 30 to 50 percent of the tensile detachment forces, and the bending detachment of the Indica ${\times}$ Japonica hybrid was 0.1 to 0.3 N which was 7 to 21 percent of Japonica types. 15. The detachment force of the lower portion was little bigger than that of the upper portion in a penicle and was not significantly affected by the harvesting period from September 28 to October 20. 16. The tensile and bending detachment forces decreased with decrease of the moisture content from 23 to 13 percent (w.b.) by the natural drying, and the decreasing rate of detachment forces along the moisture content was the greater in the bending detachment force than the tensile detachment force.