• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.66-72
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• 2009

The detection methods are required to monitor and diagnose the abnormality on the insulation condition inside a gas-insulated switchgear (GIS). Due to a good sensitivity to the products decomposed by partial discharges (PDs) in $SF_6$ gas, the development of a SWNT gas sensor is actively in progress. However, a few numerical studies on the diffusion mechanism of the $SF_6$ decomposition products by PD have been reported. In this study, we modeled $SF_6$ decomposition process in a chamber by calculating temperature, pressure and concentration of the decomposition products by using a commercial CFD program in conjunction with experimental data. It was assumed that the mass production rate and the generation temperature of the decomposition products were $5.04{\times}10^{-10}$ [g/s] and over 773 K respectively. To calculate the concentration equation, the Schmidt number was specified to get the diffusion coefficient functioned by viscosity and density of $SF_6$ gas instead rather than setting it directly. The results showed that the drive potential is governed mainly by the gradient of the decomposition concentration. A lower concentration of the decomposition products was observed as the sensors were placed more away from the discharge region. Also, the concentration increased by increasing the discharge time. By installing multiple sensors the location of PD is expected to be identified by monitoring the response time of the sensors, and the information should be very useful for the diagnosis and maintenance of GIS.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.233-240
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• 2005

To discover new functional materials using edible plants, antioxidant activities of methanol extracts from various parts of seven wild vegetables were investigated in vitro. Total polyphenol contents, determined by Folin-Denis method, varied from 16.74 to $130.22{\mu}g/mg$. Radical-scavenging activities of methanol extracts were examined using ${\alpha},\;{\alpha}-diphenyl-{\beta}-pirrylhydrazyl$ (DPPH) radicals and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) assay. Inhibition effects on peroxidation of linoleic acid determined by ferric thiocyanate (FTC) method and on oxidative degradation of 2-deoxy-D-ribose in Fenton-type reaction system were dose-dependent. Athyrium acutipinulum Kodama (leaf and rood), Achyranthes japonica (Miq.) Nakai (seed), and Solidago virga-aurea var. gigantea Nakai (root) showed relatively high antioxidant activities in various systems.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.367-375
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• 2010

Understanding the interactions between earth materials and fluids is essential for studying the diverse geological processes in the Earth's surface and interior. In order to better understand the interactions between earth materials and fluids, we explore the effect of specific surface area and porosity on structural parameters of pore structures. We obtained 3D pore structures, using random packing simulations of porous media composed of single sized spheres with varying the particle size and porosity, and then we analyzed configurational entropy for 2D cross sections of porous media and cube counting fractal dimension for 3D porous networks. The results of the configurational entropy analysis show that the entropy length decreases from 0.8 to 0.2 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$, and the maximum configurational entropy increases from 0.94 to 0.99 with increasing porosity from 0.33 to 0.46. On the basis of the strong correlation between the liquid volume fraction (i.e., porosity) and configurational entropy, we suggest that elastic properties and viscosity of mantle melts can be expressed using configurational entropy. The results of the cube counting fractal dimension analysis show that cube counting fractal dimension increases with increasing porosity at constant specific surface area, and increases from 2.65 to 2.98 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$. On the basis of the strong correlation among cube counting fractal dimension, specific surface area, and porosity, we suggest that seismic wave attenuation and structural disorder in fluid-rock-melt composites can be described using cube counting fractal dimension.

• KSBB Journal
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• v.21 no.1 s.96
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• pp.72-78
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• 2006

This study was carried out to investigate the antimicrobial and antioxidative effects of mycelium cultural extract from mushroom. Mushroom mycelium was grown in a defined synthetic liquid medium and citrus extracts, and the culture extracts were examined for antioxidant and antibacterial activity. Myceliums of Phellinus linteus, Cordyceps militaris, Coriolus versicolor, Sparassic crispa, Agaricus blazei, lnonotus obliquus, Lentinus edodes, Hericium erinacium, Gonoderma lucidium in 10% citrus extract supplemented medium and synthesis medium were incubated in a shaking incubator (120 rpm, $24{\sim}30^{\circ}C$ ) for $7{\sim}15$ days. The antimicrobial activity of the culture fluid of mushroom mycelium grown in submerged liquid culture was tested against 12 microorganisms which were fish pathogens and common bacterial species. The culture extracts showed high activity against Vibrio sp. and had poor effect on Streptocouus sp., S. parauberis, S. iniae. The culture extracts obtained from the synthetic medium showed $30{\sim}93%$ of the 1,1-diphenyl-2-picrylhydrazyl radical scavenger activity, the culture extracts obtained from the citrus extracts medium exhibited antioxidant activity up to 55%.

• Journal of Gastric Cancer
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• v.9 no.1
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• pp.18-25
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• 2009

Purpose: The postoperative hospital stay after gastric cancer surgery is usually 8 to 14 days. The main reason for a prolonged hospital stay may be the 3 to 4 day period of postoperative starvation. The aim of this study is to investigate the feasibility of a critical pathway for early recovery after gastric cancer surgery, and this pathway included early postoperative feeding. Materials and Methods: One hundred three consecutive patients who underwent gastric resection and reconstruction for gastric cancer from October 2007 to June 2008 at St. Mary's Hospital were prospectively enrolled in a fast-track critical pathway. The pathway included minimal preoperative procedures, optimal pain relief, proper fluid administration, early mobilization and early enteral nutrition at postoperative 1 day. The exclusion criteria were determined preoperatively, intraoperatively and postoperatively. Results: Of the 103 patients, 19 patients were excluded for preoperative (5), intraoperative (7) and postoperative (7) reasons. Eighty-four patients (81.6%) were included in the fast-track critical pathway. Sixty-eight (88.6%) of 84 patients were discharged at the planned 8 day after surgery during the initial period of the study, and the postoperative hospital stay was shortened up to 6 days during the more recent period. Postoperative complications occurred in 22 patients (26.2%), and these were gastrointestinal track-related complications in 6 cases (3 cases of ileus, 1 case of stasis and 2 cases of leakage) and infection-related complications in 8 cases. There was no statistical difference in the incidence of morbidity according to the clinic-operative features that included age, gender, stomach resection and lymphadenectomy. Conclusion: The fast-track critical pathway with using the available exclusion criteria was a valid option for patients who underwent gastric cancer surgery.

• Journal of Genetic Medicine
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• v.7 no.1
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• pp.59-66
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• 2010

Purpose: Quantitative fluorescent polymerase chain reaction (QF-PCR) allows for the rapid prenatal diagnosis of common aneuploidies. The main advantages of this assay are its low cost, speed, and automation, allowing for large-scale application. However, despite these advantages, it is not a routine method for prenatal aneuploidy screening in Korea. Our objective in the present study was to validate the performance of QF-PCR using short tandem repeat (STR) markers in a Korean population as a means for rapid prenatal diagnosis. Material and Methods: A QF-PCR assay using an Elucigene kit (Gen-Probe, Abingdon, UK), containing 20 STR markers located on chromosomes 13, 18, 21, X and Y, was performed on 847 amniotic fluid (AF) samples for prenatal aneuploidy screening referred for prenatal aneuploidy screening from 2007 to 2009. The results were then compared to those obtained using conventional cytogenetic analysis. To evaluate the informativity of STR markers, the heterozygosity index of each marker was determined in all the samples. Results: Three autosomes (13, 18, and 21) and X and Y chromosome aneuploidies were detected in 19 cases (2.2%, 19/847) after QF-PCR analysis of the 847 AF samples. Their results are identical to those of conventional cytogenetic analysis, with 100% positive predictive value. However, after cytogenetic analysis, 7 cases (0.8%, 7/847) were found to have 5 balanced and 2 unbalanced chromosomal abnormalities that were not detected by QF-PCR. The STR markers had a slightly low heterozygosity index (average: 0.76) compared to those reported in Caucasians (average: 0.80). Submicroscopic duplication of D13S634 marker, which might be a unique finding in Koreans, was detected in 1.4% (12/847) of the samples in the present study. Conclusion: A QF-PCR assay for prenatal aneuploidy screening was validated in our institution and proved to be efficient and reliable. However, we suggest that each laboratory must perform an independent validation test for each STR marker in order to develop interpretation guidelines of the results and must integrate QF-PCR into the routine cytogenetic laboratory workflow.

• Journal of the Korean association of regional geographers
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• v.3 no.1
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• pp.115-134
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• 1997

We now live in the new era of globalization which implies the functional integration or increase of inter-dependency between internationally dispersed economic activities. As globalization impacts our various activities and daily lives, social sciences, including, geography, attempt to approach social phenomena from a global perspective. From this point of view. new regional geography, which has been articulated in recent social theory since the 1980s, also must adjust to these new world realities. This paper aims to search for a suitable methodology or approach to area study or regional geography in the era of globalization and to suggest the field of area study that Korean geographers should be concerned with in the future. This paper has reviewed the existing various methodologies of regional geography such as the ecological approach, the landscape approach. the areal differentiation approach, the system approach, the structuration theory, the spatial division of labour, and the world-system, which have deviced in the traditional and new regional geography. Peter Taylor's regional geography of world systems among them has an appropriate rationale of area study in the globalization era, because world-systems theory explains well globalization. However the regional geography of world-systems must be revised to become more suitable to the area-study approach in the globalization era. Firstly, the regional geography of world-systems explains that regions(historical regions) are made by general mechanisms of the capitalist world-economy that operate through social, economic, and political agents within regions such as individuals, households, social classes, economic enterprises, states, political movements, and many other organizations. But these mechanisms can also act through other regional agents of geographical location, natural conditions, and cultural characteristics. Therefore, the generating process of regions needs to be explained by locational, natural, and cultural elements in addition to social, economic, and political elements within regions. Secondly, Taylor's world-systems approach does not express composite characteristics of regions, because it focuses on the economic characteristics or position of regions within the world-economy. Regions incorporated into world-economy systems are not only changed economically, but also changed spatially, socially, culturally, and politically. Hence the world-systems approach must try to analyze these composite characteristics and their change of regions. Thirdly, The world-system approach proposed that the geography of regions within world-systems could be divided and analyzed as three regional types at the geographical scale such as international regions, state regions, and intra-state regions. However such a regionalization is usually not identified distinctly, because the geographical range of regions in world-systems shaped by economic boundaries of the general mechanisms of the world-economy is fluid and also occasionally overlaps with other political regions. Hence I propose that the world-systems approach should choose political boundaries of states and local autonomies in addition to economic boundaries for objective regionalization and systematic areal study. The revised regional geography of world-systems that I have suggested in this paper can be more effectively and properly applied to regional geography or area study in the globalization era. Globalization intensifies competition between states and also between local autonomies in the world. Therefore we must make efforts to study such areas or regions through the revised regional geography of world-system.

• The Journal of Engineering Geology
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• v.14 no.1
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• pp.29-46
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• 2004

It is important to identify geometries of fracture that act as a conduit of fluid flow for characterization of ground water flow in fractured rock. Fracture geometries control hydraulic conductivity and stream lines in a rock mass. However, we have difficulties to acquire whole geometric data of fractures in a field scale because of discontinuous distribution of outcrops and impossibility of continuous collecting of subsurface data. Therefore, it is needed to develop a method to describe whole feature of a target fracture geometry. This study suggests a new approach to develop a method to characterize on the whole feature of a target fracture geometry based on the Fourier transform. After sampling of specimens along a target fracture from borehole cores, effective frequencies among roughness components were selected by the Fourier transform on each specimen. Then, the selected effective frequencies were averaged on each frequency. Because the averaged spectrum includes all the frequency profiles of each specimen, it shows the representative components of the fracture roughness of the target fracture. The inverse Fourier transform is conducted to reconstruct an averaged whole roughness feature after low pass filtering. The reconstructed roughness feature also shows the representative roughness of the target subsurface fracture including the geometrical characteristics of each specimen. It also means that overall roughness feature by scaling up of a fracture. In order to identify the characteristics of permeability coefficients along the target fracture, fracture models were constructed based on the reconstructed roughness feature. The computation of permeability coefficient was performed by the homogenization analysis that can calculate accurate permeability coefficients with full consideration of fracture geometry. The results show a range between $10^{-4}{\;}and{\;}10^{-3}{\;}cm/sec$, indicating reasonable values of permeability coefficient along a large fracture. This approach will be effectively applied to the analysis of permeability characteristics along a large fracture as well as identification of the whole feature of a fracture in a field scale.

• Development and Reproduction
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• v.13 no.1
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• pp.1-11
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• 2009

Implantation itself is governed by an array of endocrine, paracrine and autocrine modulators, of embryonic and maternal origin. Window of implantation is the unique temporal and spatial expression of factors allows the embryo to implant via signaling, appositioning, attachment, and invasion in a specific time frame of $2{\sim}4$ days. When the embryo has arrived in the uterine cavity, a preprogrammed sequence of events occurs, which involves the production and secretion of a multitude of biochemical factors such as cytokines, growth factors, and adhesion molecules by the endometrium and the embryo, thus leading to the formation of a receptive endometrium. Cytokines such as LIF, CSF-1, and IL-1 have all been shown to play important roles in the cascade of events that leads to implantation. Integrin, L-selectin ligands, glycodelin, mucin-1, HB-EGF and pinopodes are involved in appositioning and attachment. The embryo also produces cytokines and growth factors (ILs, VEGF) and receptors for endometrial signals such as LIF, CSF-1, IGF and HB-EGF. The immune system and angiogenesis play an important role. The usefulness of these factors to assess endometrial receptivity and to estimate the prognosis for pregnancy in natural and artificial cycles remains to be proven. Integrins, pinopodes, glycodelin and LIF (from biopsies) are promising candidates; from uterine flushings, glycodelin and LIF are also candidates. The ideal serum marker is not available, but VEGF, glycodelin and CSF have some clinical implications. Further evaluation that includes larger groups of infertile women and fertile controls are needed to elucidate whether their presence in plasma, flushing fluid, or endometrial samples can be used as some kind of a screening tool to assess endometrial function and prognosis for pregnancy before and after artificial reproductive therapy. A better understanding of their function in human implantation may lead to therapeutic intervention, thereby improving the success rate in reproduction treatment. New molecular techniques are becoming available for measuring both embryonic and endometrial changes prior to and during implantation. The use of predictive sets of markers may prove to be more reliable than a single marker. Ultimately, the aim is to use these tools to increase implantation in artificial cycles and consequently improve live-birth rates.

• Economic and Environmental Geology
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• v.31 no.3
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• pp.185-199
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• 1998

Hydrogeochemical and environmental isotope studies were undertaken for various kinds of water samples collected in 1995-1996 from the Bugok geothermal area. Physicochemical data indicate the occurrence of three distinct groups of natural water: Group I ($Na-S0_4$ type water with high temperatures up to $77^{\circ}C$, occurring from the central part of the geothermal area), Group II (warm $Na-HCO_{3}-SO_{4}$ type water, occurring from peripheral sites), Group III ($Ca-HCO_3$ type water, occurring as surface waters and/or shallow cold groundwaters). The Group I waters are further divided into two SUbtypes: Subgroup Ia and Subgroup lb. The general order of increasing degrees of hydrogeochemical evolution (due to the degrees of water-rock interaction) is: Group III$\rightarrow$Group II$\rightarrow$Group I. The Group II and III waters show smaller degrees of interaction with rocks (largely calcite and Na-plagioclase), whereas the Group I waters record the stronger interaction with plagioclase, K-feldspar, mica, chlorite and pyrite. The concentration and sulfur isotope composition of dissolved sulfate appear as a key parameter to understand the origin and evolution of geothermal waters. The sulfate was derived not only from oxidation of sedimentary pyrites in surrounding rocks (especially for the Subgroup Ib waters) but also from magmatic hydrothermal pyrites occurring in restricted fracture channels which extend down to a deep geothermal reservoir (typically for the Subgroup Ia waters). It is shown that the applicability of alkaliion geothermometer calculations for these waters is hampered by several processes (especially the mixing with Mg-rich near-surface waters) that modify the chemical composition. However, the multi-component mineral/water equilibria calculation and available fluid inclusion data indicate that geothermal waters of the Bugok area reach temperatures around $125^{\circ}C$ at deep geothermal reservoir (possibly a cooling pluton). Environmental isotope data (oxygen-18, deuterium and tritium) indicate the origin of all groups of waters from diverse meteoric waters. The Subgroup Ia waters are typically lower in O-H isotope values and tritium content, indicating their derivation from distinct meteoric waters. Combined with tritium isotope data, the Subgroup Ia waters likely represent the older (at least 45 years old) meteoric waters circuated down to the deep geothermal reservoir and record the lesser degrees of mixing with near-surface waters. We propose a model for the genesis and evolution of sulfate-rich geothermal waters.