• Journal of Soil and Groundwater Environment
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• v.13 no.6
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• pp.40-49
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• 2008

Matrix diffusion from planar fractures was studied mathematically and through physical model experiments. Mathematical models were developed to simulate diffusion from 2D and 3D instantaneous disk sources and a 3D continuous disk source. The models were based on analytical solutions previously developed by Carslaw and Jaeger (1959). The mathematical simulations indicated that the 2D scenario produces significantly different results from the 3D scenario, the time for mass disappearance is significantly larger for continuous sources than for instantaneous sources, the normalized concentration generally decreased over time for instantaneous sources while it increased over time for continuous sources, diffusion rates decrease significantly over time and space, and the normalized mass loss from the source zone never reaches 1 for continuous sources due to the semi-infinite integral. The simulations also showed that disappearance times increase exponentially with increasing source radii and matrix porosity, and decrease with increasing aqueous-phase NAPL solubilities.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.128-138
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• 2015

Carbonation is one of the most critical deterioration phenomena to concrete structures exposed to high $CO_2$ concentration, sheltered from rain. Lots of researches have been performed on evaluation of carbonation depth and changes in hydrate compositions, however carbonation modeling is limitedly carried out due to complicated carbonic reaction and diffusion coefficient. This study presents a simplified carbonation model considering diffusion coefficient, solubility of $Ca(OH)_2$, porosity reduction, and carbonic reaction rate for low concentration. For verification, accelerated carbonation test with varying temperature and MIP (Mercury Intrusion Porosimetry) test are carried out, and carbonation depths are compared with those from the previous and the proposed model. Field data with low $CO_2$ concentration is compared with those from the proposed model. The proposed model shows very reasonable results like carbonation depth and consuming $Ca(OH)_2$ through reduced diffusion coefficient and porosity compared with the previous model.

• Journal of Sericultural and Entomological Science
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• v.53 no.2
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• pp.92-96
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• 2015

It is known that silk protein supports effectively proliferation of cell such as insect cell and hybridoma cell. Although there are many varieties of Bombyx mori silkworm, the effect of silkworm varieties on cell proliferation has not been considered in detail. We studied that characteristics of silk cocoon obtained from Baegokjam, Kumokjam, Daeseongjam silkworm varieties and whether silk protein affected cell proliferation or not. Silk sericin was prepared under high temperature and high pressure condition. Silk fibroin was prepared using $CaCl_2:H_2O:EtOH$ with different dissolution time. As a result, there are differences in silk cocoon from different silkworm varieties about cell proliferation. The proliferation was accelerated in the presence of Baegokjam silk sericin and Kumokjam silk fibroin with 5hr dissolution time. We expect that silk proteins could be a preferable culture medium supplement for stimulating the proliferation of cell. Then, this results suggest silk as a new material for medium supplement replacing with fetal bovine serum.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.69-76
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• 2021

This study is to identify the mineralogical properties of caprock samples from drilling cores of the Pohang basin, which is the research area for the demonstration-scale CO2 storage project in Korea. The interaction of water-rock-gas that can occur due to CO2 injection was identified using geochemical modeling. Results of mineralogical studies, together with petrographic data of caprock and data on the physicochemical parameters of pore water were used for geochemical modeling. Modelling was carried out using the The Geochemist's Workbench 14.0.1 geochemical simulator. Two steps of modeling enabled prediction of immediate changes in the caprocks impacted by the first stage of CO2 injection and the assessment of long-term effects of sequestration. Results of minerlaogical analysis showed that the caprock samples are mainly composed of quartz, K-feldspar, plagioclase and a small amount of pyrite, calcite, kaolinite and montmollonite. After the injection of carbon dioxide, the porosity of the caprock increased due to the dissolution of calcite, and dawsonite and chalcedony were precipitated as a result of the dissolution of albite and k-feldspar. In the second step after the injection was completed, the precipitation of dawsonite and chalcedony occurred as a result of dissolution of calcite and albite, and the pH was increased due to this reaction. Results of these studies are expected to be used as data to quantitatively evaluate the efficiency of mineral trapping capture in long-term storage of carbon dioxide.

• Journal of the Mineralogical Society of Korea
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• v.13 no.2
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• pp.73-83
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• 2000

다덕 광산 폐석내 섬아연석과 함망간탄산염 광물의 풍화현상과 그에 따른 중금속의 거동을 조사 하였다. 섬아연석은 풍화초기에 극미립 산화철의 망상구조 집합체로 교대되었으며, 후기에는 자연황이 용해중인 섬아연석과 산화철 집합체 사이에 침전되었다. 산화철 집합체에는 As가 다량 함유되어 있다. 능망간석와 함망간 방해석은 함아연산화망간의 망상구조 집합체로 교대되었으며, 함망간방해서과 함아연산화망간 사이에는 스미소나이트가 침전되었다. 선택적 용해외 X선회절분석을 이용하여 감정한 결과, 함아연산화망간은 헤테롤라이트/하이드로헤테롤라이트인 것으로 판명되었다. Zn의 일부는 규산과 결합하여 입간 공극에 월레마이트로 침전되었다. 풍화 초기에 형성되는 극미립 산화철 및 함아연산화망간의 치밀한 망상 집합체는 풍화용액의 순환을 차단하여, 모광물의 풍화 반응을 지체시키는 지화학적 장벽 역할을 하였다. 이에 따라 망상구조 내에 조성된 국지적 미환경하에서 풍화중간산물들이 침전되었다. 이상의 연구 결과로 다음과 같은 사항을 추론할 수 있다. 섬아연석의 Fe와 함망간탄산염의 Mn은 각각 산화철과 산화망간으로 침전되어 산성화에 기여하였다. 폐광석 더미내 As의 활동도는 저결정질 산화철에의 흡착에 의해 조절되며, Zn의 활동도는 미소환경조건에 따라 하이드로헤테롤라이트/헤테롤라이트, 스미소나이트, 월레마이트 등의 다양한 이차광물의 용해도에 의하여 조절된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1229-1235
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• 2015

Scaffold fabrication technology using a 3D printer was developed for damaged bone tissue regeneration. A scaffold for bone tissue regeneration application should be biocompatible, biodegradable, and have an adequate mechanical strength. Moreover, the scaffold should have pores of satisfactory quantity and interconnection. In this study, we used the polymer deposition system (PDS) based on fused deposition modeling (FDM) to fabricate a 3D scaffold. The materials used were polycaprolactone (PCL) and alginic acid sodium salt (sodium alginate, SA). The salt-leaching method was used to fabricate dual pores on the 3D scaffold. The 3D scaffold with dual pores was observed using SEM-EDS (scanning electron microscope-energy dispersive spectroscopy) and evaluated through in-vitro tests using MG63 cells.

• Journal of the Korean Wood Science and Technology
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• v.41 no.4
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• pp.302-309
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• 2013

The highly porous cellulosic aerogels were prepared by freeze-drying method using sodium hydroxide-urea aqueous solution in the process of dissolution, gelation, regeneration and organic solvent substitution. The structural characteristics of porous aerogel were analyzed using scanning electron microscopy and nitrogen adsorption apparatus. As a result, the dissolving pulp was completely dissolved, but filter papers and holocellulose were divided into two layers (dissolved and undissolved parts) in the process of centrifugation. The structure of aerogel from dissolved pulp showed porous pores in the surface and net-shaped network in the inner part. Aerogels from filter paper and holocellulose had the condensed porous network surface and the open-pore nano-fibril network inner structure. Undissolved form of fibers was observed in the aqueous solution of aerogel from holocellulose. The BET value ($S_{BET}$) of aerogel from dissolved pulp was ranged in 260~326 $m^2/g$, and it was decreased with the increase of concentration. Whereas, the $S_{BET}$ value of aerogel from filter paper (198~418 $m^2/g$) was increased with the increase of concentration. The $S_{BET}$ value of aerogel from holocellulose were 137 $m^2/g$ at 2% (w/w) of cellulose, and it was increased to maximum 401 $m^2/g$ at 4% (w/w) of cellulose. Then, it was decreased at 5% (w/w) of cellulose.

• Economic and Environmental Geology
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• v.41 no.3
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• pp.327-334
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• 2008

Understanding the chemical characteristics of sediments and the nutrient diffusion from sediments to the water body is important in the management of surface water quality. Changes in chemical properties and nutrient concentration of a submerged soil were monitored for 6 months using a microcosm with the thickness of 30cm for upland soil and 15cm of water thickness above the soil. The soil color changed from yellowish red to grey and an oxygenated layer was formed on the soil surface after 5 week flooding. The redox potential and the pH of the pore water in the microcosm decreased during the flooding. The nitrate concentration of the surface water was continuously increased up to $8\;mg\;l^{-1}$ but its phosphate concentration decreased from $2\;mg\;l^{-1}$ to $0.1\;mg\;l^{-1}$ during flooding. However, the concentrations of $NH_4^+$, $PO_4^{3-}$, Fe and Mn in the pore water were increased by the flooding during this period. The increased $NO_3^-$ in the surface water was due to the migration of $NH_4^+$ formed in the soil column and the oxidation to $NO_3^-$ in the surface water. The increased phosphate concentration in the pore water was due to the reductive dissolution of Fe-oxide and Mn-oxide, which scavenged phosphate from the soil solution. The oxygenated layer played a role blocking the migration of phosphate from the pore water to the water body.

• The Journal of Engineering Geology
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• v.2 no.1
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• pp.58-69
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• 1992

Change in atmospheric pressure produce sizable fluctuafions in wells penetrafing confined aquifers. The relationship is inverse; that is, increases in atmospheric pressure produce decreases in water levels, and conversely. When atmospheric pressure changes are expressed in terms of a column of water, the raflo of water level change to pressure change expresses the barometric efficiency of an aquifer. In the study area, aquifers are developed in the fractures, joints, bedding planes and occasionally in solufion cavities of marl interbeds. The barometric efficiency of the aquifer varies from 8 to 90%, indicating that Confined, Unconfined and Semi-Confined condifions exist locally. The barometric efficiency is characteristic of the aquifer itself and observed in the field is inversely proportional to specific storage or the storage coefficient. It is remalned in question to derive the relationship between B.E. and S.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.378-387
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• 2010

We present the results of laboratory measurement of porosity and electrical resistivity for the samples collected near marine hydrothermal deposit to provide fundamental perspective of physical properties for future electromagnetic survey. The rock cores are sampled from the host rock, pumice, hydrothermal altered zone, and chimney. These samples are featured as easily brittle, rough surface with large pores, having components easily solvable in the water. We suggest systematic approach for measuring weights, volumes of core samples to calculate density and porosity. Measurements reveal that the resistivities of black host rock, gray host rock, pumice and chimney are 102, 39, 11, 0.1 ohm-m, respectively, when the core samples are saturated with saline water of $32,000\;{\mu}S$/cm (0.5 ohm-m) at temperature of $2.5^{\circ}C$ and these correspond to the factors of 5 for sea water, 110 for pumice and 390~1020 for host rocks with respect to the resistivity of chimney. We also confirm that resistivity of rock samples saturated with water decrease with temperature linearly over the temperature range of $20{\sim}80^{\circ}C$.