• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.195-200
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• 2011

KS F 2782 (for shotcrete accelerators) standard cross-section of tunnel construction or repair is a reinforcement used in the field of shotcrete accelerators as a criterion in assessing shotcrete performance. Thus, KS F 2782 by standard accelerator will determine the nature of the product of concrete accelerators that will be used to record variations in the product roles, through determination of the quality of the experimental method to identify only the quality of the many variables that exist. This evaluation standard has so far distinguished accelerator products in indoor experiments that do not meet quality standards but were mostly for an on-site accelerator mixed with the shotcrete after being quite satisfied with the level of quality in a certain number of products. This observation is derived from the results of an indoor experiment considered to verify whether the site is suitable for indoor experiments, and whether its actual location in the city is relevant to the accelerator quality, to find a way to test if it fits. This study centers on the material conditions of the shotcrete accelerator and a variety of experimental results, and used the Gilmore needle to compare the compressive strength and KS F 2782 specification of the accelerator as a means to ensure product quality conformity analysis and for further research experiments. In conclusion, a portion of KS F 2782 standard that fixes the problems that can be resolved from the ground up as a whole is not a review for the domestic reality. As an indoor experiment to ensure uniformity in the field when applied in a sufficient correlation, complement must be in place.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.383-388
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• 2019

The present study evaluated experimentally the effects of the type and content of plastic fine aggregates on cement mortar in order to utilize waste platics as raw materials of concrete. The two kinds of plastics, LLDPE and HDPE were used, and the mixing rate of plastic fine aggregates was increased 0, 25, 50, 75, 100%. The mortar of LLDPE fine aggregate and HDPE fine aggregate showed similar tendency in flow and material separation resistance, density and water absorption, compressive strength and flexural strength by age. The flowability of mortar mixed with plastic fine aggregates was increased up to 50% but decreased at 75% or more. The material separation resistance of mortar with plastic fine aggregates was also dramatically decreased. On the other hand, due to the low density of plastics, the density of mortar decreased with the mixing of plastic fine aggregates. Due to the low adhesion between plastic fine aggregates and cement, the compressive strength by age was decreased in proportion to the mixing ratio of plastic aggregate, but the flexural strength of each age decreased with maintaining a certain level at 50% or more of plastic fine aggregate content.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.167-174
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• 2020

Many researches have been conducted to utilize recycled aggregates in Korea, but since most sources of recycled aggregates are not clear, there is a lot of uncertainty in applying the existing research results on recycle of aggregates generated from nuclear power plants. In this study, therefore, in order to investigate the possibility of recycling coarse aggregates generated through dismantling of nuclear power plants in Korea, recycled coarse aggregates were produced from concrete simulating nuclear power plants in Korea. Using the recycled coarse aggregates, concrete was mixed in consideration of the mixing ratio of the recycled coarse aggregates, and the mechanical properties were experimentally investigated. From the test results, as the mixing ratio of recycled coarse aggregates increased. concrete compressive strength, tensile strength, and elastic modulus generally decreased up to 36, 37, and 27% from the mechanical properties of normal concrete, respectively. Therefore, it can be concluded that limitation on the mixing ratio of recycled coarse aggregates is necessary when coarse aggregates are recycled through dismantling of nuclear power plants.

• Journal of the Korean association of regional geographers
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• v.18 no.3
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• pp.253-267
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• 2012

The study looked into the type and characteristics of debris landforms in Mt. Mudeung. By focusing on the representative area, we aimed to categorize the debris landforms based on the morphologic and genetic characteristcis. The types of debris areas in Mt. Mudeung can be divided into the exposed debris type, mixed type of matrix, and the boulder-hidden type. Supply of block in the debris slope area displays different features depending on types of rocks. For the stony slopes of andesite, the block must be moved from the columnar joint or cliff in the upper part. The andesite debris slopes display dominant edge shape while displaying no round shape. The granite stony slopes display dominant round shape and the present exposed slope was assumed to be formed as the core stone which was deep weathered moved along slope during the periglacial era and the matrix was removed after post-glacial era. The movements of blocks are assumed to be caused by solifluction process. The joint area where granite and andesite areas meet, granite is located beneath andesite area, and this implies that blocks were actively freezing and creeping by solifluction and freezing and thawing at that time. It can be assumes that the granite matrix formed plain slope and then andesite boulder covered up the slope. Currently, the blocks in the stony slopes of Mt. Mudeung shows almost no mobility and the stony slopes created under periglacial climate can be considered to be fossil landform.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.9
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• pp.1366-1375
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• 2008

This studies were carried out in order to develope environmentally-friendly fiber materials and substitute resources of Paper mulberry. Various plant fibers such as New Zealand flax, Indian mallow, Kuzu vine and Yucca were used as raw materials of hand-made papers. We rotted these 4 kinds of plant fibers and removed non-cellulose. After rotting, the pulping rate(%) and the length of fibers in pulps were measured. The physical characteristics of papers made of various plants fiber were investigated and the probabilities of practical use were considered. The results were as follow: The non-cellulose contents of plant fibers were $30{\sim}40%$ and those contents must be lower down to 8% to be able to manufacture the hand made papers. The lignin in pulps were removed almost and the hemicellulose were partially removed to reach up to appropriate level of the pulp rates and fiber lengths. The more hemicellulose removed, the finer fiber thickness were and rapidly the lower Hanji tensile strength were. But the tear strength of these plants of hand-made papers do not decreased so much as tensile strength. So the property of 4 types of plant fibers might be of great advantages to make hand-made papers. Both tensile and tear strengths of Hanji of New Zealand flax, Indian mallow, Kuzu vine and Yucca were higher than Paper mulberry hand-made paper. When 30% of mulberry paper were mixed, the mixing effect showed maximum. Because of the functions of all plant fiber hand-made papers showed better than those of Paper mulberry hand-made paper, 4 types of plant fibers could be substitute Paper mulberry.

• Microbiology and Biotechnology Letters
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• v.38 no.2
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• pp.151-157
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• 2010

Barley malt produces two different $\alpha$-amylase isozymes (AMY1 and AMY2), which share up to 80% of amino acid sequence identity with each other. However, their enzymatic properties differ remarkably. In this study, five chimeric enzymes between AMY1 and 2 were constructed by staggered extension process (StEP) technique, and their enzymatic properties were characterized. According to the results, chimeric AMY-D2, D8, and E12 showed the mixed or intermediate types of calcium-dependent activity between AMY1 and 2. Meanwhile, only AMY-E10 chimera could be significantly inhibited by barley $\alpha$-amylase/subtilisin inhibitor (BASI) protein. Chimera AMY-C6 showed the same calcium-dependency as AMY1, while AMY-E10 was closely similar to AMY2. As a result, it can be proposed that some amino acid residues in the region II, III, and IV of barley $\alpha$-amylases can play very important roles in the interaction with BASI, and those in III, V, VI, and VII may partly affect on the calcium-dependent activity.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.169-178
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• 2000

Perovskite oxide catalysts doped on porous alumina beads are prepared in a citric acid solution. To investigate the applicability of the catalysts to the hot gas cleanup, a series of experiments on the reduction characteristics of $NO_x$ by CO as a reducing agent are carried out in a packed bed reactor containing the catalysts. Parameters tested are the operating temperature and $CO/NO_x$ molar ratio. It is found that mixed complex oxides of $La_{0.5}Sr_{0.5}CoO_3$, $SrAl_{12}O_{19}$ and $LaAl_{11}O_{18}$ are uniformly distributed on the alumina beads. The conversion efficiency of $NO_x$ by CO sharply increases with the operating temperature up to $700^{\circ}C$ and then approaches 100% when $CO/NO_x$ molar ratio is greater than 1.0. The conversion efficiency of $NO_x$ is maintained by over 98% during a continuous operation for 23 hours at $800^{\circ}C$ and space velocity of $10700hr^{-1}$.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.100-109
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• 2009

Korean Plecopteran research was started in 1921, and it has advanced greatly during last 20 years. Among families the family Nemouridae and Chloroperlidae are composed of plentiful species. Since North Korean Plecopteran research was begun in 1938, it made good progress by foreigners not North Korean in the 1970's. Subsequently a few species has been added up recently, and among families the family Perlidae and Nemouridae contain most abundant species. Totally Korean Plecoptera consists of 43 species in 25 genera in 10 families, and North Korean 37 species in 26 genera in 10 families. Among them 13 species are common in both. And Korean names of Plecopteran species were mixed in Hangeul-type and Chinese-type, on the other hand in North Korean names there were some cases of Hangeul-type, but most of species have no Korean names. In Korea, particularly Ministry of Environment designated and controlled domestic biological resources as Korean Species that Require Approval when shipping abroad and Korean endemic species, which include 9 species and 11 species in Plecoptera respectively. Finally two genera and four species gained new Korean names as follows: genus Megaleuctra (Keun-Kkoma-Gang-Do-Rae-Sok), genus Haploperla (Han-Nok-Saek-Gang-Do-Rae-Sok), Nemoura brevicercia (Min-Gang-Do-Rae), Nemoura espera (Kkot-Min-Gang-Do-Rae), Amphinemura baei (Je-Ju-A-Ga-Mi-Min-GangDo-Rae) and Amphinemura rai (A-Ga-Mi-Min-Gang-Do-Rae).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.2
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• pp.115-122
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• 2010

In this study, the removal of Cs and Tc from a simulated fission products (FP) solution which were co-dissolved with U during the oxidative-dissolution of spent fuel in a mixed carbonate solution of $(Na_2CO_3-NaHCO_3)-H_2O_2$ was investigated by using a selective precipitation method. As Cs and Tc might cause an unstable behavior due to the high decay heat emission of Cs as well as the fast migration of Tc when disposed of underground, it is one of the important issues to removal them in views of the increase of disposal safety. The precipitation of Cs and Re (as a surrogate for Tc) was examined by introducing sodium tetraphenylborate (NaTPB) and tetraphenylphosponium chloride (TPPCl), respectively. Precipitation of Cs by NaTPB and that of Re by TPPCl were completed within 5 minutes. Their precipitation rates were not influenced so much by the temperature and stirring speed even if they were increased by up to $50^{\circ}C$ and 1,000 rpm. However, the pH of the solution was found to have a great influence on the precipitation with NaTPB and TPPCl. Since Mo tends to co-precipitate with Re at a lower pH, especially, it was effective that a selective precipitation of Re by TPPCl was carried out at pH of above 9 without co-precipitation of Mo and Re. Over 99% of Cs was precipitated when the ratio of [NaTPB]/[Cs]>1 and more than 99% of Re, likewise, was precipitated when the ratio of [TPPCl]/[Re]>1.

• Applied Biological Chemistry
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• v.47 no.2
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• pp.192-196
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• 2004

In order to measure cellular physiological activity including ion channel activity, protoplasts were isolated from the root tissue of tomato plant. The general methods recommended were not efficient enough to make protoplasts from the root tissue. Among various conditions tested, we found that a two-step treatment of osmosis is very efficient for the isolation of protoplasts. In this procedure, root tissues were preincubated in a solution containing 300 mM sorbitol for 30 min. Then, they moved to the reaction solution containing 700 mM sorbitol as well as cell wall-digesting enzymes. The formation of protoplast was greatly increased by this method. In order to find the optimal condition of the two-step method, various conditions of pH, osmotic pressure, incubation time, and the concentrations of cell wall-digesting enzymes were tested. The yield of protoplast isolation was maximal at pH 5.0 after 2 hr incubation. Mixed enzymes of 3% cellulase, 1 % macerozyme, and 0.1 % pectolyase showed maximal protoplast isolation. The physiological activity of isolated protoplast evaluated by measuring the cellular ATPase activity was as high as that measured from the preparation of root tissue. The protoplasts isolated by this method were remained healthy up to 4 hrs which is enough time to measure the cellular physiological activity. These results show that the two-step treatment of osmotic pressure was successful to obtain high yield of healthy protoplast from tomato root tissue.