• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.275-282
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• 2014

Particle-reinforced metal matrix composites exhibit a strengthening effect due to the particle size-dependent length scale that arises from the strain gradient, and thus from the geometrically necessary dislocations between the particles and matrix that result from their CTE(Coefficient of Thermal Expansion) and elastic-plastic mismatches. In this study, the influence of the size-dependent length scale on the particle-matrix interface failure and ductile failure in the matrix was examined using finite-element punch zone modeling whereby an augmented strength was assigned around the particle. The failure behavior was observed by a parametric study, while varying the interface failure properties such as the interface strength and debonding energy with different particle sizes and volume fractions. It is shown that the two failure modes (interface failure and ductile failure in the matrix) interact with each other and are closely related to the particle size-dependent length scale; in other words, the composite with the smaller particles, which is surrounded by a denser dislocation than that with the larger particles, retards the initiation and growth of the interface and matrix failures, and also leads to a smaller amount of decrease in the flow stress during failure.

• Journal of Mushroom
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• v.14 no.4
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• pp.179-183
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• 2016

Button mushroom(Agaricus bisporus) are cultivated on wheat straw or rice straw based compost. In this study different compost formular, sawdust as carbon source and chicken manure as nitrogen source were used for button mushroom cultivation. Two steps of sufficient composting process was required to be successful in the cultivation. 1) the substrates are needed to be mixed periodically under the aerobic condition in the phase I process. 2) the temperature is need to be maintained between 55 and 65? for more than three days in the phase II process. Results showed that button mushroom was possible to grow normally with sawdust based compost. However the mushroom yield was less than that of the conventional compost formular(rice straw or wheat straw). The new compost formular developed from this study may be useful but further research may need to improve button mushroom cultivation more efficiently.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1057-1068
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• 2014

This paper proposes elastic-plastic constitutive relations for a composite material with two phases-inclusion and matrix phases-using a homogenization scheme. A thermodynamic framework is employed to develop non-local plasticity constitutive relations, which are specifically represented in terms of the second-order gradient terms of the internal state variables. A combined two back-stress evolution equation is also established and the degradation of the state and internal variables is expressed by continuum damage mechanics in terms of the damage factor. Then, deformation localization is analyzed; the analysis results show that the proposed model yields a wide range of shear band formation behaviors depending on the evolution of the specific internal state variables. The analysis results also show good agreement with the results of simplified Rice instability analyses.

• Microbiology and Biotechnology Letters
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• v.31 no.3
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• pp.250-256
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• 2003

Lactic acid bacteria with amylolytic and acid producing activities can ferment starch directly to lactic acid thereby producing a monomer for the production of biodegradable poly lactic acid (PLA). In this study, the strain producing L-lactic acid from soluble starch was isolated from Nuruk. The isolated strain was identified as Enterococcus sp. through its morphological, cultural, biochemical characteristics as well as the 16S rDNA sequence analysis, and named Enterococcus sp. JA-27. Enterococcus sp. JA-27 produced exclusively L-lactic acid from soluble starch as a carbon source. The optimal conditions for the maximum production of L-lactic acid from Enterococcus sp. JA-27 were 30 C, pH 8, 1.5 % soluble starch as a substrate and 3.5 % tryptone as a nitrogen source, 0.1 % $K_2$$HPO_4$, 0.04 % $MgSO_4$. $7H_2$O, 0.014 % $MnSO_4$$.$4$H_2O$, 0.004% $FeSO_4$$.$$7H_2$O. Batch and fed batch culture were carried out and the former was more effective. L-Lactic acid production in the optimum medium was significantly increased in a 7 L jar fermenter, where the maximum L-lactic acid concentration was 3 g/L. For the purification of lactic acid in fermented broth, two stage ionexchange column chromatographies were employed and finally identified by HPLC.

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2002.12a
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• pp.58-73
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• 2002

지방산을 이용한 살충비누의 제조와 이를 이용한 해충의 환경친화적 방제연구를 수행하였고 그 내용을 요약하면 다음과 같다. 1. 각 지방산의 중화가(Acid value)를 기준으로 비누화에 필요한 수산화칼륨의 투입량을 결정할 수 있었으며, 야자지방산의 경우 중화가가 266.3mg KOH/g으로 지방산 1kg당 수산화칼륨 266g이 필요한 것으로 나타났다. 2. 25%의 비누 함량이 되게 제조하기 위해서 지방산별 반응식을 조사하였고, 이에 따라 물의 첨가량을 결정할 수 있었으며, 야자지방산을 이용한 25% 살충비누의 제조에는 지방산 1kg에 수산화칼륨 266g과 물 3.459 ${\ell}$ 가 소요되고 제조된 비누액은 4.644 ${\ell}$인 것으로 나타났다. 또한 사용하는 물은 연수를 이용하여야 하였다. 3. 25% 제조된 살충비누의 물성을 조사한 결과 젤리상의 올레인산 비누를 제외하고는 점도가 낮은 액상이었으며, 산도는 알카리성으로 25% 야자지방산의 경우 pH 9이상으로 나타났다. 또한 50% 이상 고농도의 살충비누를 제조하면 냉각 후 젤리상태가 되어 희석하여 이용하는데 불편하였다. 4. 살충비누 제조공정의 요인으로 반응온도는 중탕방식으로 90$^{\circ}C$이상, 교반속도는 60 ${\sim}$ 120 rpm. 반응시간은 30분 이상이 양호한 것으로 나타났다. 5. 살충비누제조 공정은 중탕, 교반 가능한 반응기를 활용하여 (1) 수산화칼륨 수용액 제조 및 가온(90$^{\circ}C$) (2) 지방산 투입 (3) 30분이상 교반 반응 (4) 냉각을 통해 제조할 수 있었다. 6. 고추진딧물의 포장 방제가 조사시험결과 모든 지방산에서 살충효과를 나타냈으며, 지방산의 탄소수가 낮을수록, 살포 농도가 높을수록, 살포회수가 증가할수록 방제가가 높은 경향이었다. 7. 25% 야자지방산의 경우 50배에서 5일간격 2회처리 후부터 고추에 발생하는 진딧물에 대한 방제가가 92%이상이 되었으며, 100배액에서는 5일간격 3회처리 후부터 94%의 방제가를 나타내었다. 8. 양배추의 복숭아진딧물에 대한 25% 야자지방산 살충비누 50배액의 살포결과 1회 처리후 95%이상, 2회 처리후 100%에 가까운 방제가를 나타냈다. 9. 강낭콩의 점박이응애에 대한 25% 야자지방산 살충비누 50배액, 100배액 살포결과 2회처리 후부터 거의 100%에 가까운 방제효과를 보였으며, 알에 대한 부화억제효과도 인정되었다. 10. 효과증진제 첨가 실험결과 이소프로필알콜 0.1%이상 첨가 살포에서 2회처리시에 약간의 살충력 증진 효과를 보였으며, 규조토 첨가는 효과가 없는 것으로 나타났다. 11. 노지재배 고추의 약해검정결과 25%카프릴산비누 50배액을 제외하고는 약해가 발생하지 않았으며, 25% 카프론산 비누의 100배액은 고추 유묘기에 약해를 나타내었다. 양배추에서는 25% 카프릴산 비누 100배액에서 약해를 보였으나, 25% 야자지방산의 경우 50 ${\sim}$ 100배액 어디에서도 액해를 보이지 않았다. 별도로 적용한 시험에서, 토마토의 경우에도 25% 야자지방산 비누 50 ${\sim}$ 100배액 모두 약해를 발생하지 않았으나, 오이에서는 25% 야자지방산 비누 100배액에도 약해를 나타내었다. 12. 이상의 결과, 천연지방산을 이용하여 유기농업에 허용되는 각종의 살충비누를 제조할 수 있었으며, 방제가 조사결과 진딧물, 응애 등 껍질이 연약한 곤충의 방제에 효과적인 것으로 나타났다. 따라서 제조된 살충비누를 활용하면 환경친화적인 해충방제가 가능하다고 판단되었다.

• Korean Journal of Organic Agriculture
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• v.19 no.2
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• pp.229-243
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• 2011

Consumers' interest and government's support for the fruits rapidly increased organic fruit productions. This study was examined to compare the soil physicochemical and microbial properties of orchards soil in conventionally and organically management systems. Organic cultivation had lower soil bulk density, solid phase, and penetration resistance than the conventional cultivation. Soil pH and organic matter contents increased from March to August, and the values were greater in the organic cultivation than the conventional cultivation. Total nitrogen (N) and phosphorous concentrations decreased from March to August, and the organic soils had greater N but lower phosphorous concentrations than the conventional soils. Soil microbial carbon biomass increased 36% and 15% for organic and conventional cultivations, respectively, from March to August. Soil microbial N biomass was greater in June than March or August, and the organic cultivation had a greater biomass N compared to the conventional cultivation. Soil dehydrogenase and chitinase activities were greater in June than in March or August. ${\beta}$-glucosidase activity declined in both cultivations, while the phosphatase activity increased. Organic cultivation had greater enzyme activities in March, June, and August, except for the acid phosphatase activity in June.

• Resources Recycling
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• v.8 no.3
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• pp.9-17
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• 1999

The study investrgated the properti es of lh$\xi$ dust~ from felToalloy manufacture, The chemical composition, composItron material, particle size and shapes of the bulk dust, sized dust and magnetically separated dust were llivestigated. As the result, we s suppose that the dust from HLgh Carbon Fenomauganesc Manufacturing Process is not sufficient as soource material of Mn because of the low Mn conteut (13.5%) aud complicated composition material The dust from Bag Filter of AOD Process is m mainly made up of $0.2~2\mu\textrm{m}$ $Mn_3O_4$ (Hausmatmite) particle in spherical shape and the Mn content is 63.1%. The dust from Cooler of AOD Process is mainly made up of coarse $Ca(OH)_2$ Mn, $Fe_yO_2$ $SiO_2$ and fine $Mn_3O_1$.

• Journal of Conservation Science
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• v.24
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• pp.1-11
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• 2008

The Unhyungung Water Container in the possession of the Seoul Museum of History in Korea is consisted of a calcareous marble developed laminated bedding and numerous argillaceous veinlets. This monument should need to conservation treatment because of black discoloration and seriously numerous cracks. Vertical and horizontal cracks in the monument are developed following stratification and argillaceous veinlets that are relatively low coherence between the rock materials. We have proved that the material inducing discoloration on the surface is carbon which is formed by deposited organic matters. As the result of the ultrasonic measurements, although highly surface weathering degree, the physical properties of the Unhyungung Water Container is confirmed slightly weathered state. The depths of cracks in the monument are calculated at maximum 60mm in some cracks completely penetrating into the wall and at minimum 9mm in the other crack. The cracks, developed following veinlet, are revealed that there penetrate from an outer wall to an inside wall for the monument. And most depths of cracks, developed following stratification, are calculated 20 to 30mm. This result will offer a significant data for conservation of the Unhyungung Water Container.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.612-619
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• 2016

In this research, an alumino-borosilicate foamed glass with sound absorption property was prepared using the waste borosilicate glass obtained from the recycling process of waste liquid crystal display (LCD) panel. A 100 g of pulverized waste borosilicate glass with the particle size of under 325 mesh, was mixed with 0.3 g (wt/wt) of graphite, each 1.5 g (wt/wt) of $Na_2CO_3$, $Na_2SO_4$ and $CaCO_3$ as a foaming agent, and 6.0 g (wt/wt) of $H_3BO_3$ and 3.0 g (wt/wt) of $Al_2O_3$ as a pore control agent. Following mixture was under the foaming process for 20 minutes at a foaming temperature of $950^{\circ}C$. The result yielded the foaming agent with 45% of the opened porosity and 0.5-0.7 of the sound absorbing coefficient. This alumino-borosilicate foamed glass with the sound absorption property showed excellent physical and mechanical properties such as density of $0.21g/cm^3$, bending strength of $55N/cm^2$ and compression strength of $298N/cm^2$ which can be ideally used as sound absorption materials with heat-resisting and chemical-resisting property.

• Composites Research
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• v.28 no.6
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• pp.356-360
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• 2015

In this paper, the carbon fiber reinforced plastic is processed as the double cantilever beam in order to estimate the fracture behavior of composite and is carried out with the static analysis as the mode I. The specimen sizes are 25 mm, 30 mm, 35 mm and 40 mm. And the material property is used with carbon. As the analysis result of mode I, the adhesive part is detached latest by the small force at the specimen thickness of 25 mm. The largest force is happened at the specimen thickness of 40 mm. The defection of the adhesive interface is shown slowest at the displacement of 9.75 mm at the specimen thickness of 25 mm. And the defection is shown quickest at the displacement of 7.82 mm at the specimen thickness of 40 mm. This defection is due to the fracture of specimen. The result of this study on the defection of the adhesive interface and the reaction force due to this defection is thought to be contributed to the safe structural design of the carbon fiber reinforced plastic.