• Journal of the Korean Geotechnical Society
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• v.29 no.2
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• pp.5-14
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• 2013

Among the various thermal properties, thermal conductivity of soils is one of the most important parameters to design a horizontal ground heat exchanger for ground-coupled heat pump systems. It is well known that the thermal conductivity of soil is strongly influenced by its density and water content because of its particulate structure. This paper evaluates some of the well-known prediction models for the thermal conductivity of particulate media such as soils along with the experimental results. The semi-theoretical models for two-component materials were found inappropriate to estimate the thermal conductivity of dry soils. It comes out that the model developed by Cote and Konrad provides the best overall prediction for unsaturated sands available in the literature. Also, a parametric analysis is conducted to investigate the effect of thermal conductivity, water content and soil type on the horizontal ground heat exchanger design. The results show that a design pipe length for the horizontal ground heat exchanger can be reduced with an increase in soil thermal conductivity. The current research concludes that the dimension of the horizontal ground heat exchanger can be reduced to a certain extent by backfilling materials with a higher thermal conductivity of solid particles.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.184-189
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• 2013

$Ba_2SiO_4:Eu^{2+}$ ($B_2S:Eu^{2+}$) powders were prepared by firing the dry gel obtained by the sol-gel and the hybrid process (sol-gel and combustion), respectively, and their structure and luminescence were investigated. Tetraethyl orthosilicate (TEOS) was used as a Si source. The phase transition was observed with the TEOS content. With 1.2M TEOS, the powders prepared by the sol-gel process without prior calcination were composed of the $B_2S:Eu^{2+}$ single phase, whereas those by the sol-gel and the hybrid process with prior calcination consisted of the dominant $B_2S:Eu^{2+}$ and minor $BaSiO_3:Eu^{2+}$ ($BS:Eu^{2+}$) phases and their emission intensities were approximately two times higher than those without prior calcination. The hybrid process could reduce the process time innovatively compared to the sol-gel process, even though the former was a little inferior to the latter in the emission intensity of $B_2S:Eu^{2+}$. With 1.1M TEOS, the $B_2S:Eu^{2+}$ single phase was obtained by the hybrid process, and its green emission was observed at 505 nm originated from the $4f^65d^1{\rightarrow}4f^7$ transition of $Eu^{2+}$ ions.

• Resources Recycling
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• v.19 no.1
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• pp.33-39
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• 2010

The spheric sintered body with $6{\pm}2mm$ diameter was manufactured in a rotary kiln at $1125^{\circ}C$/15 min using green body formed by pelletizing the batch powder composing of coal bottom ash produced from power plant and dredged soil by 70:30, wt%. And the physical properties of sintered body (BD) were analyzed to confirm the possibility for applying to an absorbent to restore a contaminated soil. The sintered body had a giant pore above 100 ${\mu}m$ and a fine pore below 10 ${\mu}m$, and bulk density was 1.4. Also its specific surface area, porosity and void proportion were $12.0m^2/g$, 30.1% and 38.2% respectively. The crushed body (BD-C), produced by crushing a BD specimen into an irregular shape with a aspect ratio of about 2, was similar to BD specimen at bulk density and pore size distribution. But it had superior values of specific surface area, porosity and void proportion compared with BD specimen owing to a decreased apparent volume due to conversion of closed pore existed at interior of BD to open pore during a crushing process. The IEP of sintered body occurred at about pH=5, so the optimum pH condition of reacting aqueous solution could be known before bonding a microbe to the sintered body. Hence, the optimum void proportion and porosity of an absorbent can be obtained by appropriate mixing a BD with BD-C from the base data calculated in this study.

• 보존과학연구
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• s.32
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• pp.75-87
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• 2011

The materials analysis is important in conservation science for cultural assets since conservators can make appropriate decision of treatment and environment through understanding manufacturing, period and materials. Palsapumdo is the painting of Palsapum which was given by Yi Sun-shin from the emperor Shinjong in The Ming Dynasty. Palsapumdo painted with various pigments on the fabric has remained to adhere a sheet of lining paper. In this study, we carried out the fiber identification about the fabric and lining paper and the analysis of the pigments. This study identified a fabric and a lining paper and analised pigments for the painting. As a result of fabric analysis, it was confirmed as cotton because ribbon twists and shape of kidney bean in a cross section. After the analysis of lining paper, color changed to yellow by Graff "C" staining tests, and had short fiber and tracheid. Therefore, it is supposed to be a paper which is made of conifer pulp. In addition, the results of SEM-EDS, the pigments are indicated as Orpiment($As_2S_3$), Minium($Pb_3O_4$), Hematite($Fe_2O_3$), Emeraldgreen ($C_2H_3As_3Cu_2O_8$), Ultramarine [$2(Na_2O{\cdot}Al_2O_3{\cdot}2SiO_2){\cdot}Na_2S_2$], talc[$Mg_3Si_4O_{10}(OH)_2$], bariumsulfate($BaSO_4$) and brass.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.480-486
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• 2002

Six strains of intestinal pathogenic bacteria were inoculated into kimchi at the preparation time, and the influence of kimchi fermentation on the growth of these pathogenic bacteria was investigated. The population of coliform bacteria in the kimchi raw materials, and its changes in the kimchi sample during fermentation were also determined. Among the raw materials, highest populations of coliform bacteria were detected in ginger and green onion, followed by Chinese cabbage, red pepper, and garlic. Populations of pathogenic bacteria (inoculated strains) and coliform bacteria in kimchi decreased as pH decreased with fermentation. Coliform bacteria disappeared at pH 3.9 in Chinese cabbage kimchi samples. Clostridium perfringens ATCC 13124, Listeria monocytogenes ATCC 19111, Salmonella typhimurium KCTC 1625, Staphylococcus aureus KCTC 1621, Vibrio parahamolyticus ATCC 27519, and Escherichia coli O157 H:7 ATCC 43894 were not detected at pH values less than 4.1, 3.7, 3.8, 3.8, 3.7, and 3.7 in Chinese cabbage kimchi, and at pH values less than 4.5, 4.0, 4.2, 4.2, 4.2 and 4.1 in mustard leaf kimchi, respectively. The juice of mustard leaf and allyl isothiocyanate exhibited high antimicrobial activities on the pathogenic bacteria, whereas the lowest on lactic acid bacteria. These results indicated that fermentation is useful to improve the safety of kimchi, and the antimicrobial effect of mustard leaf kimchi is mainly due to the major pungent compound of mustard leaf, allyl isothiocyanate.

• The Journal of the Petrological Society of Korea
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• v.27 no.4
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• pp.207-222
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• 2018

Celestial Chart Stones (original and reproduction) in the National Palace Museum are representative scientific cultural heritage of Korea. Material analysis and nondestructive deterioration assessment were conducted for long-term preservation of these stones. Material analysis revealed that the original was composed of slate and the reproduction was made of dolostone. The original consists of quartz, mica, dolomite minerals, while the reproduction was made up of dolomite, calcite and forsterite. Major deterioration factors of the original stone were cracks and breakouts. In case of the reproduction, scratches and artificial materials were mainly observed. The green and black surface contaminants present at the sides and back of the two celestial chart stones were interpreted as resin-based paint materials. The physical property evaluation using ultrasonic velocity showed a low velocity in the upper left side of the original, while the front right side of the reproduction showed a weak property. Meanwhile, the To-Tc method using ultrasonic velocity was applied to major cracks that impede stability of the original. As a result, it has been calculated that the beginning and the center of the crack are the deepest.

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.268-274
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• 2018

In this study we suggest a humidity-sensitive color sensor using a one-dimensional photonic crystal and Hong Kong University of Science and Technology-1 (HKUST-1), which is a metal-organic framework (MOF) substance. One-dimensional photonic crystals have a photonic band gap, due to a periodic refractive-index change, and block and reflect light components in a specific wavelength band. The refractive index of HKUST-1 differs in dry and humid environments. Herein we designed a sensor using the presence of the photonic band gap, with FDTD simulation. As a result of optical analysis, the color conversion of the reflected light was superior to the color conversion of the transmitted light. When the center wavelength of the photonic band gap was 550 nm, the maximum peak value of the wet environment increased by a factor of about 9.5 compared to the dry environment, and the color conversion from achromatic to green was excellent as a sensor. The results of this study suggest the application of MOF materials to moisture sensors, and the nanostructure design of MOF materials will expand the applications to industrial devices.

• Journal of Adhesion and Interface
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• v.22 no.3
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• pp.85-90
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• 2021

Generally, the tensile strength of carbon fiber reinforced composite (CFRP) should be determined to produce this material. The tensile strength was performed based on ASTM D3039, and this test could cause the error by specimens and human. In this research, the CFRP tensile test was performed with different thickness of specimens and tap, adhesive for attaching tap, and pressure of jig to hold the specimens, while the test was performed based on ASTM D3039. The tensile stress and modulus exhibited differently with different specimen thicknesses, and the 1~1.5 mm thickness of the specimen was optimized. In the case of 0.28 MPa jig pressure, the slip or fracture at the clamping area of the specimen has not occurred, and specimens were fractured to the center section of the specimen. The adhesive to attach jig on specimen should be used to exhibit high adhesive stress. Experimental parameters could cause errors. It is expected to achieve an accurate tensile property evaluation of composite materials via improvements in adhesives, tabs, and jigs.

• Microbiology and Biotechnology Letters
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• v.48 no.4
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• pp.455-462
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• 2020

Leuconostoc mesenteroides CJNU 0705 was isolated from a breast milk sample and identified by 16S rRNA gene sequencing and confirmed by its ability to produce dextran from tryptic soy agar plates supplemented with 2% sucrose. This strain can absorb various heavy metals including lead (Pb) and cadmium (Cd) which are both found in fine dust and have been shown to be harmful to human skin. In addition, Leu. mesenteroides CJNU 0705 has demonstrated antimicrobial activity against Propionibacterium acnes, the primary causative agent of acne. Given these traits it was natural to evaluate the use of this strain in the fermentation of several natural extracts from green tea, carrot, annual wormwood, parsley, broccoli, and corn silk, which are known to improve skin health, to see if it could increase their dextran content when supplemented with no sucrose, 2% sucrose, or 2% sucrose and 3% yeast extract. The extracts supplemented with both yeast and sucrose were found to produce the most dextran, which was confirmed by the scanning electron microscope (SEM) images. These results suggest that Leu. mesenteroides CJNU 0705 and its fermented natural extracts could be used as functional materials for improving human skin health.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.6
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• pp.613-622
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• 2020

The South Korean government plans for a 37 % reduction in CO2 emissions against business as usual by 2030. Subsequently, the Ministry of Land, Infrastructure and Transport declared a 26.9 % reduction target in greenhouse gas emissions from buildings by 2020 and established the Green Standard for Energy and Environmental Design (G-SEED) to help improve the environmental performance of buildings. Construction companies often work with consulting firms to prepare for G-SEED certification. In the process, owing to inefficient data sharing and work connections, it is difficult to achieve economic efficiency and obtain certification. The objective of this study was to develop an economic model to assist contractors in achieving the required G-SEED scores for materials and resources. To do this, we automated the process for material comparison and selection on the basis of an analysis of actual consulting data, and developed a model that selects material alternatives that can meet the required scores at a minimum cost. Information on materials is input by applying a genetic algorithm to the optimization of alternatives. When the model was applied to actual data, the construction cost could be lowered by 79.3 % compared with existing methods. The economical material selection model is expected to not only reduce construction costs for owners desiring G-SEED certification but also shorten the project design time.