• 한국지반환경공학회 논문집
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• 제24권8호
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• pp.13-20
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• 2023

지반이상대 구간을 지나는 터널은 시공 중 또는 시공 후 지반융기, 균열, 전단 파괴 등의 이상변위 발생이 많이 보고되고 있다. 이러한 이상변위가 지속되거나 큰 경우에는 최종적으로 터널 붕괴위험의 우려가 있으며, 다양한 보강공법을 사용하여 터널 붕괴위험을 저감시키고 있다. 본 연구에서 살펴본 터널은 막장이 완전 풍화상태가 주를 이루며 부분적으로 심한 풍화상태로 분포하는 구간에 시공되었다. 시공 중 터널 내공변위를 침범하여 강지보 및 숏크리트를 재시공하였으며, 기존 설치된 flat형 인버트의 제거없이 현 상태에서 라이닝 철근 보강공법을 적용하였다. 이러한 보강공법을 적용 후 실시한 계측 자료를 바탕으로 바닥의 융기 가능성 구간에 대하여 수치해석적인 방법으로 장기변위 예측을 통해 터널의 장기적인 안정성을 검토하였다.

• 한국산학기술학회논문지
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• 제9권6호
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• pp.1775-1781
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• 2008

가교제의 종류가 헬리콥터 연료탱크의 자기밀폐층 소재로 적용시키기 위한 천연고무 스폰지의 팽윤에 미치는 효과를 조사하였다. 과산화물과 황을 섞은 가교방식과 과산화물에 의한 가교방식을 채택하였다. 천연고무 콤파운드를 Kneader와 Roll-Mill을 활용하여 제조하고, 고압조건의 프레스에서 부분 가교시킨 후 대기압의 금형에서 발포와 완전가교를 실시하였다. 얻어진 스폰지의 겉보기밀도를 측정하고 스폰지의 셀구조를 주사전자현미경을 통하여 관찰하였다. 톨루엔, 이소옥탄과 항공유를 사용하여 실온에서 팽윤실험을 실시하였다. 용매에 2분 동안 침적 후 얻어지는 부피팽윤비 값은 과산화물 가교에 의한 천연고무 스폰지가 비슷한 양의 황과 과산화물의 혼합가교에 의한 경우보다 높았다. 스폰지의 겉보기밀도와 셀구조는 과산화물 함량에 매우 민감하였으며 이는 또한 천연고무 스폰지의 팽윤거동에 영향을 미쳤다. 천연고무 스폰지가 연료와 접촉하여 신속한 팽윤이 얻어지기 위하여 금형에서 동시에 발생하는 두 가지 반응인 발포제의 분해반응과 천연고무의 가교반응을 적절히 조절하는 것이 중요하다.

• Nuclear Engineering and Technology
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• 제45권1호
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• pp.41-52
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• 2013

Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high-level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

• 한국막학회:학술대회논문집
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• 한국막학회 1995년도 춘계 총회 및 학술발표회
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• pp.50-51
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• 1995

The swelling behavior of hyddrogels has been interested in many applications of drug carriers. These gels show reversible swelling changes in response to pH, electric currcnt, and temperature. Among others, the temperature-responsive behavior of poly(N-isopropylacrylanxide) (p(NIPAAm)) was studied, because a lower critical solution temperature(LCST) is in the vicinity of 32$\circ$C, and remarkable temperature-response can be obtained. We propose a novel composite membrane, which is appropriate for transporting drug ingredients above the transition temperature. Our object was to design a high permeation system above the shrinking temperature of p(NIPAAm). The membrane was composed of a matrix polymer and thermosensitive p(NIPAAm) hydrogel. The flux pattern of 4-acctamidophen through membrane in response of temperature was opposite to that of p(NIPAAm) membrane.

• 방사선산업학회지
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• 제2권1호
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• pp.15-19
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• 2008

In order to develop a water-solubility and biocompatibility, chemically modified chitosan, N,O-carboxymethylchitosan (NOCC), was synthesized and the NOCC hydrogels were prepared by using ${\gamma}-ray$ irradiation instead of chemical reagents. The FT-IR spectroscopy, swelling behavior, gel content and mechanical property such as gel strength of the hydrogel were measured. When the NOCC solution concentration was 15 wt% and the dose of irradiation was less than 50 kGy, the NOCC hydrogels had an excellent hydrophilicity and exhibited a good swelling behavior and mechanical properties.

• 폴리머
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• 제25권4호
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• pp.545-557
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• 2001

Hydroxypropyl cellulose (HPC)를 이용하여 제조한 메탄올의 유방성 용액에 두 종류의 aliphatic dicarboxylic acid chlorides (succinyl chloride 와 suberoyl chloride)를 첨가하여 주형시킴에 의해 cholesteric 질서를 지닌 가교필름들을 제조하였다. 가교필름의 cholesteric pitch의 온도의존성과 물과 메탄올중에서의 가교필름의 팽윤거동을 검토하였다. 필름들은 cholesteric 액정상의 특징적인 지문조직을 나타내었으며 이들의 pitch는 HPC 자체와 동일하게 온도가 상승함에 따라 증가하였다. 그러나 모든 가교시료들은 주어진 온도하에서 HPC가 나타내는 pitch에 비해 대단히 크며 가교제의 농도 및 길이의 증가에 의해 증가하였다. 가교시료들은 두 용매중에서 이방성 팽윤을 나타냈다. 이방성 팽윤의 정도는 용매와 가교제의 종류에 다소 의존하나 검토된 가교제의 농도에는 거의 의존하지 않았다.

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.734-743
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• 2017

In order to investigate the swelling behavior and fuel-cladding interaction mechanism of U-10Zr alloy metallic fuel at very low burnup, an irradiation experiment was concisely designed and conducted on the China Mianyang Research Reactor. Two types of irradiation samples were designed for studying free swelling without restraint and the fuel-cladding interaction mechanism. A new bonding material, namely, pure aluminum powder, was used to fill the gap between the fuel slug and sample shell for reducing thermal resistance and allowing the expansion of the fuel slug. In this paper, the concise irradiation rig design is introduced, and the neutronic and thermal-hydraulic analyses, which were carried out mainly using MCNP (Monte Carlo N-Particle) and FLUENT codes, are presented. Out-of-pile tests were conducted prior to irradiation to verify the manufacturing quality and hydraulic performance of the rig. Nondestructive postirradiation examinations using cold neutron radiography technology were conducted to check fuel cladding integrity and swelling behavior. The results of the preliminary examinations confirmed the safety and effectiveness of the design.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.739-742
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• 2003

생분해성인 Curdlan을 이용하여 pH 의존성 약물 전달계 개발을 위한 실험을 수행한 결과, pH 1,4에서 약물 방출 보다 pH 7.4에서 약물 방출이 10배 이상 증가하였다. 이러한 결과로 curdlan acetate microsphere는 pH 의존성 약물 전달계로 유용하다고 판단된다.

• Korea-Australia Rheology Journal
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• 제11권3호
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• pp.225-232
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• 1999

This study presents 1-dimensional simple model for sheet casting or rectangular fiber spinning process. In order to achieve this goal, we introduce the concept of force flux balance at the die exit, which assigns for the extensional flow outside the die the initial condition containing the information of shear flow history inside the die. With the Leonov constitutive equation that predicts non-vanishing second normal stress difference in shear flow, we are able to describe the anisotropic swelling behavior of the extrudate at least qualitatively. In other words, the negative value of the second normal stress difference causes thickness swelling much higher than width of extrudate. This result implies the importance of choosing the rheological model in the analysis of polymer processing operations, since the constitutive equation with the vanishing second normal stress difference is shown to exhibit the characteristic of isotropic swelling, that is, the thickness swell ratio always equal to the ratio in width direction.

• Nuclear Engineering and Technology
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• 제33권1호
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• pp.62-72
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• 2001

The one-dimensional finite element program was developed to analyze the coupled behavior of heat, moisture, and air transfer in unsaturated porous media. By using this program, the simulation results were compared with those from the laboratory infiltration tests under isothermal condition and temperature gradient condition, respectively. The discrepancy of water uptake was found in the upper region of a bentonite sample under isothermal condition between numerical simulation and laboratory experiment. This indicated that air pressure was built up in the bentonite sample which could retard the infiltration velocity of liquid. In order to consider the swelling phenomena of compacted bentonite which cause the discrepancy of the distribution of water content and temperature, swelling and shrinkage factors were incorporated into the finite element formulation. It was found that these factors could be effective to represent the moisture diffusivity and unsaturated hydraulic conductivity due to volume change of bentonite sample.