• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.1-12
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• 2016

In this study, the impact of sand and weathered granite soil is analyzed by changing the internal temperature from $20^{\circ}C{\sim}70^{\circ}C$C by installing a heating coil inside the triaxial cell. To check the effect on weathered granite soil due to increase of temperature and number of heating-coiling cycles are analyzed by measuring the temperature by using thermometer installed inside the triaxial cell and due to that deviator stress also occurred during the consolidated undrained test. To analyze the effect of weathered granite soil with change of temperature during undrained testing. The deviator stress and pore pressure is measured. As a result, pore pressure increases and the deviator stress decreases with rise of temperature.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.453-462
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• 1995

In connection with the safe storage of high level nuclear waste, effect of $H_2O$$_2$ on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without $H_2O$$_2$. The experimental results show that $H_2O$$_2$ increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as $H_2O$$_2$ concentration increased, indicating that pitting resistance was decreased by the existence of $H_2O$$_2$ in the electrolyte. These effect of $H_2O$$_2$ on corrosion of 304L stainless steel are considered to be similar to those of ${\gamma}$-irradiation. To compare the effects of $H_2O$$_2$ with those of $O_2$, cathodic and anodic polarization curves ore made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of $H_2O$$_2$ on the corrosion behavior were tory similar to those of $O_2$ such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by $H_2O$$_2$ were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively.y.

• Applied Biological Chemistry
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• v.33 no.4
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• pp.293-300
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• 1990

The physical and chemical properties of dry acorn starch(DS), defatted acorn starch (DFS) and reincorporated acorn starch(RIS) were investigated. Swelling power and solubility of all starch sample, were exhibited two stage behavior. It had a little change on the pasting temperature of DS and DFS but the peak viscosity and breakdown value of DFS was somewhat higher than those of DS and RIS. Flow behavior of gelatinized starch pastes showed a pseudoplastic behavior and flow behavior index was lower than unit The consistency coefficient showed concentration and temperature dependency. The activation energies of DS, DFS and RIS were from $1.70Kca1/g\;{\cdot}\;mol$ to $3.75Kca1/g\;{\cdot}\;mol$.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.117-124
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• 2020

The present research focuses on a methodology to describe shearing response of clay with respect to temperature. An increase of temperature shifts the normal consolidation line to move down in the plane of void ratio and mean effective stress. The critical state line, however, does not move as much as the normal consolidation line in accordance with temperature increase. As temperature increase, therefore, the difference between the critical state mean effective stress and the pre-consolidation pressure reduces. To reflect this easily, the present study applies a bounding surface consisting of two parts divided by the critical state mean effective stress. This study calibrated a bounding surface for the soft Bangkok clay and performed elemental simulation for undrained triaxial compression tests. The elemental simulation showed that the model can describe the mechanical response upon temperature of clay without complex hardening and evolution rules compared to the experimental data.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.113.2-113.2
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• 2011

Sn-Ag계 합금은 대표적인 무연 솔더 조성으로 전자제품의 실장 및 접합에 적용되어 왔으며, 태양전지 분야에서도 모듈의 전극과 bus바로 사용되는 등 다양한 분야에서 사용되고 있다. 그러나 최근 Ag 가격의 급격한 상승과 솔더 접합부의 신뢰성을 보다 향상시키고자 Ag의 함량을 줄이고 다원계 합금 조성의 무연 솔더 연구가 활발히 진행되고 있다. 본 실험에서는 기존의 연구 결과를 바탕으로 Sn-1.0Ag-0.5Cu-0.4In 4원계 무연솔더 조성에 Bi를 첨가하여 최적의 융점과 용융구간을 가지는 5원계 Sn-Ag-Cu-In-Bi 계 솔더 합금을 설계하였다. 이 설계된 합금은 기존의 유연 솔더인 Sn-Pb와 대표적인 무연 솔더인 Sn-3.5Ag와 각각의 특성을 비교 분석하였다. 젖음성을 평가하기 위하여 wetting balance tester를 이용하여 실험을 행하였고 Differential Scanning Calorimetry(DSC)를 분석하여 젖음 정도와 조성 분석 및 고상점과 액상점 등의 녹음 거동을 확인하였다. 또한 각각의 조성별 전단응력에 따른 파괴 거동을 분석하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.205-208
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• 2008

Steel-embedded composite piers can enhance the resistance of core concrete by confinement of the steel elements and also can strengthen the stability of the embedded steel elements by concrete parts, so that the resistance of the composite members and seismic requirements can be provided without increasing section dimensions and self-weight. While modular composite piers with single segment do not need prestressing, precast segment composite piers with multiple segments need to have prestressing to prevent excessive cracking at the joints. Initial stresses and deformation by the introduced prestress are changed by long-term properties of concrete and need to be considered in the design. This paper deals with the prestress losses by the measurement of load cells, strains of reinforcements, concrete and embedded steel tubes.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.675-682
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• 2002

The beam of composite structure composed of the RC structure in the end part and steel structure in the central palt were investigated during cyclic loading, in order to evaluate strength, stiffness, and deformational capacity. The parameters used in this study include the amount of reinforced steel bar between the steel beam and RC structure and the existence of the sticking plate. Test results showed that all specimens had stabilized hysteresis loops. Likewise, the specimens with sticking plate had higher load-carrying capacity compared with the one without it. In addition, the stiffness of the composite structure was higher than the steel structure. All specimens also showed good rotational capacity.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.257-260
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• 2008

The heat resistance of steel materials tends to weaken due to its high heat transfer properties, which might result in deteriorated strength because of rapidly rising temperature on surface in a fire. Particularly in case of CFT column that bears tensile stress of the structure on its external steel members, a numerical analysis on deterioration of strength and variation of stress shall be first carried out to ensure the structure will have sufficient fire resistance. In the study, based on values obtained from the high temperature material property test of steel materials and concrete, the test to forecast the fire behavior of CFT column was conducted using a finite element analysis method (ABAQUS). An Analysis in a bid to predict the heat transfer and the behavior characteristics by varying the strength of the concrete filled to the range of 40MPA and 50MPA was carried out. As a result of analysis of CFT column on condition of 180-minute exposure under the standard fire condition, 123mm of strain appeared with 40MPA model, while 91mm contraction with 50MPA model.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.192-202
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• 2013

The domestic demand of natural gas has increased continuously due to the sudden rise of oil price and regulations on greenhouse gas to global warming. In order to improve the supply security of natural gas market in Korea, the agreement on supply of pipeline natural gas (PNG) in Russia was signed between Gazprom and Korea Gas Corporation in 2008. If the supply plan of Russian natural gas is realized, underground storage facilities would be required in order to balance supply and demand of natural gas because the gas demand is concentrated in the winter. This study investigated the safety of the storage facility in quantitative way considering several design parameters such as gas pressure, depth of the storage cavern, rock condition and in-situ horizontal stress ratio. Two dimensional stress analyses were conducted using axi- symmetry condition to examine the behavior of cavern depending upon suggested design parameters. Results showed that the factor of safety, defined as the ratio of 'shear strength'/'shear stress', was largely affected by the depth, rock class and gas pressure but was insensitive to the coefficient of lateral pressure(Ko).

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.649-652
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• 2012

회전익항공기의 연료셀 내부는 연료보관 및 연료를 엔진으로 공급하기 위한 배관과 구성품들이 배치되어 있다. 특히, 기동헬기는 전장에서 사용되는 헬기로써, 수 km 고도에서 비행하는 고정익기보다 비행고도가 낮기 때문에 피탄될 가능성이 높다. 따라서, 항공기의 생존성을 극대화하기 위해서는 피탄시 유체내부 상승압력에 의한 내부 LRU 가 받는 영향성을 검토하여 설계되어야 함은 주지의 사실이다. 그러나, 내탄시험은 연료셀 자체의 제작비용 및 준비기간이 상당히 소요되고, 실탄사용에 따른 시험수행의 제약 때문에 수치모사를 통한 관련 데이터의 확보가 필요하다. 이를 위해 본 연구에서는 유체-구조 수치모사 프로그램인 Autodyn을 이용하여 회전익항공기 연료셀의 내탄 수치모사를 수행하여, 피탄 후 연료셀 내부에서의 탄 거동을 분석하고 유체내부의 압력과 연료 셀 자체의 등가응력을 평가하였다.