• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2000년도 가을 학술발표회 논문집
• /
• pp.335-342
• /
• 2000

In this study, the swelling characteristics of reconstituted clayey soil were investigated by STD and CRS test. The strain rate during loading was constant i.e. 0.05 %/min, 0.03 %/min and during unloading was varied in proportion to 1/1, 1/5, 1/10 and 1/15 of strain rate during loading. From this study the following conclusions were obtained; (1) There were similar values, especially, during unloading in case of 1/10 or 1/15 of strain rate during loading and the test results between STD and CRS were much to be alike. (2) The cross point of effective stress versus excess pore water pressure ratio curve, was increased during unloading, while the stress level of the cross point was decreased. The stress level can be separated into two zones according to the swelling index named Cs1 and Cs2. From the test results, the values of Cs1 were approximately constant irrespective of strain rate during unloading, but the values of Cs2 were much influenced by strain rate. (3) In CRS consolidation tests, it was found that unloading strain rate did not affect on the existence of zone.

• Geomechanics and Engineering
• /
• 제28권2호
• /
• pp.171-180
• /
• 2022

Time-dependent stress-strain behaviour significantly influences the compressibility characteristics of the clayey soil. In this paper, a series of oedometer tests were conducted in two loading patterns and investigated the time-dependent compressibility characteristics of Indian Montmorillonite Clay, also known as black cotton soil (BC) soil, during loading-unloading stages. The experimental data are analyzed using a new non-linear function of the Elasto-Visco-Plastic Model considering Swelling behaviour (EVPS model). From the experimental result, it is found that BC soil exhibits significant time-dependent behaviour during creep compared to the swelling stage. Pore water entrance restriction due to consolidated overburden pressure and decrease in cation hydrations are responsible factors. Apart from it, particle sliding is also evident during creep. The time-dependent parameters like strain limit, creep coefficient and C_αe/C_c are observed to be significant during the loading stage than the swelling stage. The relationship between creep coefficients and applied stresses is found to be nonlinear. The creep coefficient increases significantly up to 630 kPa-760 kPa (during reloading), and beyond it, the creep coefficient decreases continuously. Several parameters like loading duration, the magnitude of applied stress, loading history, and loading path have also influenced secondary compressibility characteristics. The time-dependent compressibility characteristics of BC soil are presented and discussed in detail.

• 한국전산구조공학회논문집
• /
• 제14권4호
• /
• pp.515-523
• /
• 2001

본 논문에서는 고준위 핵폐기물의 지하 처분 시 사용되는 핵폐기물 처분장치의 기본 구조설계에 필요한 처분장치내의 핵 폐기물다발들을 지지하는 내부 삽입물의 구조형상과 재원 또 처분장치의 화학적 부식을 방지하기 위해 외곽에 설치하는 외곽쉘과 위아래 덮개의 두께를 결정하기 위하여 처분장치 구조물에 대한 선형정적 구조해석을 수행하였다. 해석 대상 처분장치는 가압경수로와 중수로의 핵폐기물 처분장치를 사용하였다. 일반적으로 핵폐기물 처분장치는 지하수백 미터에 위치하는 화강암 등의 암반 내에 설치하게 되는데 이 때 지하수의 침수에 의한 지하수압 및 처분장치 외곽에 완충장치로 설치하는 벤토나이트 버퍼의 팽윤압을 견디어 내야 한다. 따라서 이와 같은 압력의 변화에 따른 처분장치 구조물에 발생하는 응력 및 변형 등을 알기 위해서는 처분장치 구조물에 대한 구조해석을 수행해야 된다. 이를 위하여 본 논문에서는 처분장치에 대하여 선형정적 구조해석을 수행하였다.

• 한국섬유공학회:학술대회논문집
• /
• 한국섬유공학회 2003년도 The Korea-Japan Joint Symposium
• /
• pp.33-34
• /
• 2003

Lyocell yarns were treated with NaOH, liquid ammonia, high pressure steam and polycarboxylic acids, and dyed with five reactive dyes. The water content of the samples was also measured by the centrifugal and chromatographic techniques. The total pore volume w as substantially increased by NaOH treatment, while decreased by high pressure steaming. The pore size distributions for the dyed samples were affected by the dyes used.

• 폴리머
• /
• 제34권3호
• /
• pp.253-260
• /
• 2010

본 연구에서는 조직확장 응용을 위한 생체적합성 생분해성 하이드로젤을 제조하고, 그 기본특성을 분석하였다. 친수성 고분자인 poly(ethylene glycol)의 양 말단에 다양한 몰비의 D,L-lactide와 glycolide를 개환 중합시켜 PLGA-PEG-PLGA 삼중공중합체를 합성한 뒤 비닐기를 도입하여 하이드로젤 제조 시 swelling/degradation controllers(SDC)로 사용하였다. 합성한 SDC와 PEG diacrylate를 사용하여 라디칼 중합으로 제조한 하이드로젤은 건조된 상태에서도 유연하고 탄성을 보였으며 분해테스트에서는 SDC의 조성과 SDC/PEG의 몰비에 따라 다양한 팽윤지연시간과 분해기간을 갖는 것으로 나타났다. 그 밖에 기계적 물성과 팽윤압력을 측정하였고, 이식시험을 통해 이식용 하이드로젤을 사용목적에 맞게 이식하거나 삽입하였을 때의 생체 조직의 국소적인 병리적 양상을 육안관찰과 현미경적 관찰을 통하여 평가하였다.

• 한국가구학회지
• /
• 제22권1호
• /
• pp.54-62
• /
• 2011

The metalized wood composites with natural grain of imported Juglans nigra, which was impregnated with low melting alloy were manufactured and evaluated in this study. And the proper manufacturing conditions was also investigated in this study. The low melting alloy with bismuth (Bi) and tin (Sn) which are harmless to humans, was applied to this new composites. The composites showed not only no defects of discoloration, delamination, swelling, and cracking, because of high dimensional stability and low thickness swelling, but also much improved performance such as high bending strength, high hardness, abrasion resistance, high thermal conductivity as floor materials. This study also suggested the proper impregnating condition, such as 10 minutes of the preliminary vacuum time, $186^{\circ}C$ of the heating temperature and 10 minutes of the maintaining pressure time at the pressure of $30kgf/cm^2$. This metalized wood composites showed 7 times higher density than control, great increase in bending strength from $131.8N/mm^2$ to $192.3N/mm^2$, and great increase in hardness from $18.2N/mm^2$ to $90.4N/mm^2$. The composites demonstrated not only high emissivity of 91%, high shilding effectiveness of 92.59∼99.99%, high fire resistance but also great decrease in abrasion depth, water absorption and thickness swelling.

• 폴리머
• /
• 제38권5호
• /
• pp.626-631
• /
• 2014

물을 정수하기 위해서는 그에 상응하는 막대한 양의 에너지가 소모되고, 이 때 소모되는 에너지는 환경오염을 야기할 수 있다. 이러한 문제 때문에 정수 공정 중에 상대적으로 낮은 에너지를 요구하는 정삼투 방법이 많은 관심을 받아왔다. 그러나 정삼투 방법은 오염수로부터 물을 끌어오기 위해서 높은 삼투압을 발생시킬 수 있는 유도용질이 필요하다는 점 때문에 어려움이 있었고 본 연구에서는 poly(N-isopropylacrylamide)(PNIPAM)이라는 온도 감응성 고분자 하이드로젤을 기본으로 하는 양쪽성 이온 물질과의 공중합체와 interpenetrating polymer network(IPN) 구조를 가지는 하이드로젤을 제작하고 이를 정삼투막에 부착시켜 성공적으로 유도용질 역할을 수행함을 확인하였다. 공중합체의 경우 팽윤비가 급격히 증가한 것을 확인할 수 있었으나, 그 만큼의 온도감응성이 떨어지는 모습을 보였고 IPN 구조의 경우는 온도감응성과 팽윤비 값이 PNIPAM 젤에 약간 못 미쳤다. 여기에 팽윤비 값과 삼투압의 관계를 확인하였다.

• Bulletin of the Korean Chemical Society
• /
• 제24권9호
• /
• pp.1333-1338
• /
• 2003

Hollow Fiber flow field-flow fractionation (HF-FlFFF) has been tested in polyacrylonitrile (PAN) membrane channel in order to compare it with polysulfone (PSf) membrane channel. It has been experimentally shown that the separation time of 0.05-0.304 ${mu}m$ polystyrene latex (PSL) standards in PAN membrane channel is shorter than that in PSf channel by approximately 65%. The optimized separation condition in PAN membrane is ${\dot V}_{out}/{\dot V}_{rad}=1.4/0.12\;mL/min$, which is equal to the condition in PSf membrane channel. In addition both the resolution ($R_s$) and plate height (H) in PAN membrane channel are better than that in PSf membrane channel. The membrane radius was obtained by back calculation with retention time. It shows that the PSf membrane is expanded by swelling and pressure, but the PAN membrane doesn't expand by swelling and pressure.

• Korean Membrane Journal
• /
• 제3권1호
• /
• pp.39-50
• /
• 2001

The counter-diffusion of two gaseous substances permeating a polymeric membrane has been investigated both experimentally and theoretically. The aim of the study was to find mutual effects, if any, that could influence the permeability and diffusivity data. The experimental data were obtained with an isostatic permeameter operating at ambient pressure and 303 K: helium, nitrogen, carbon dioxide methane were used as permeating gas at different partial pressure; helium or nitrogen as equilibrating or carrier gas. No evident mutual effect of the counter-diffusing gas was observed. The theoretical analysis gave some insight into the phenomena and it was concluded that at near-atmospheric pressures, and in the absence of swelling phenomena no mutual interaction exists. On a theoretical basis any mutual interaction between diffusing and counter-diffusing gases could only occur: i) at high pressures , when the free movement of permeating gas molecules within the polymer is hindered by the counter-diffusing gas; ii) when a large part of the free volume fraction is occupied by the counter--diffusing gas; iii) swelling phenomena modify the structure and free volume fraction of the polymer.

• 대한의용생체공학회:의공학회지
• /
• 제34권3호
• /
• pp.117-122
• /
• 2013

Hyaluronic acid(HA) microbeads were synthesized by dropping the sodium hyaluronate(Streptococcus) solutions in NaOH into a solution mixture of divinyl sulfone(DVS) in 2-methyl-1-propanol, followed by stirring, cleaning and drying process at room temperature. The initial experimental conditions are crosslinking time(CLTi) of 5 h, crosslinking temperature(CLTe) of room temperature, injection air pressure(IAPr) of 5 psi, and DVS concentration( DVSc) of 0.2 vol%, respectively. Then, parametric studies were performed by varying the parameters to investigate the morphology, the porosity, the swelling ratio and the size of the beads. The microbead size pattern was not regular to function of the degree of crosslink. It was observed that the swelling ratio, the degree of crosslink, and the pore size can be controlled by adjusting the CLTi, CLTe and DVSc. Among the parameters investigated, the smallest bead size can be achieved by varying the CLTi parameter. The lowest swelling ratio, as an indication of the highest degree of crosslink, can be obtained by varying CLTe.