• Korean Journal of Plant Resources
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• v.25 no.2
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• pp.257-270
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• 2012

The taxonomic relationship of 3 taxa in $Carex$ sect. $Siderostictae$ were revealed by morphological and molecular studies. The morphological characteristics of Korean $Carex$ siderosticta Hance, which is a type species of sect. $Siderostictae$, was first reviewed in comparison with previous records in order to identify the difference. Then the distribution map of this species was formulated through previous floral literatures and voucher specimens. Although the leaf shape which is represented by length/width ratio showed a great variation depending on habitat condition, the rhizome creeping patterns, the presence of hair on the surface leaf margin and perigynium were shown to be good diagnostic characters to define delimitation of species level. The results from molecular study supported $C.$ $ciliatomarginata$ Nakai should be ranked independently on species level.

• Polymer(Korea)
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• v.26 no.6
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• pp.710-717
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• 2002

Molecularly imprinted polymers were prepared in particle forms by crosslinking methacrylic acid (MAA)) using all trans-retinoic acid as a template. The HPLC column packed with the prepared molecular imprinted polymers showed high capability in separation of retinoid derivatives. The column capacity factor and selectivity increased with increasing MAA to template ratio when the incorporated template amount was fixed, as it statistically generated more binding sites between host molecules and template. Molecularly imprinted polymer particles prepared via an emulsion polymerization method were round-shaped and their sizes were more uniformly distributed, but their separation capability was inferior to those obtained by solution polymerization method. It was presumably because the loss of interaction strength between MAA and the template due to hydrogen bonding either between MAA and water or between template and water during the synthesis of molecularly imprinted polymers.

• Polymer(Korea)
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• v.39 no.2
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• pp.346-352
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• 2015

Polyalphaolefin (PAO) is a synthetic lubricant that is superior to mineral-based lubricants in the terms of physical and chemical characteristics such as low pour point, high viscosity index (VI), and thermal and oxidation stability. Several kinds of PAOs have been synthesized by using 1-pentene, 1-hexene, 1-octene, or 1-dodecene as monomer with three kinds of aluminum-based Lewis acid catalysts via cationic polymerization. The control of the catalytic performance and physical properties of PAO such like molecular weight, kinematic viscosity, pour point, and viscosity index was done by changing polymerization parameters. The alkyl aluminum halide-based catalysts show better catalytic activity than that of the conventional $AlCl_3$ catalyst. The microstructure of PAO was investigated by means of TOF-MS (time of flightmass spectroscopy) analysis in order to elucidate the correlation between the performances of the lubricant (VI, pour point) and the molecular structure of PAO. The VI of PAO increases with increases in the carbon number of ${\alpha}$-olefin. In other words, the performances of PAO as a lubricant strongly depended on the branch length of PAO.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.91-99
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• 2007

It is well-known that the presence of NOM (natural organic matter) in water has a negative effect on removing taste and odor compounds by activated carbon adsorption. Therefore, various means such as enhanced coagulation are applied to reduce the NOM. The presence of taste & odor compounds in drinking water even parts per trillion, is enough to generate customer dissatisfaction. Therefore, the aim of this study was to evaluate carbon usage rate (CUR) for conventional coagulation (CC) and enhanced coagulation (EC) in order to improve the efficiency of adsorption of taste and odor compounds. Also, Effect of CC and EC on molecular weight fraction and the early stage breakthrough of 2-MIB and Geosmin are evaluated. When the enhanced coagulation was adapted for pretreatment for activated carbon adsorption the operation period could be prolonged by 3.5~4 times. CUR for CC was about 2 times greater than CUR for EC and this means that EC has more adsorption capacity than CC. To analyze effect of EC and CC on breakthrough of 2-MIB quantitatively, adsorbed NOM mass was calculated based on unit mass of activated carbon. In the early stage breakthrough of 2-MIB, total adsorbed NOM was 23.72mg/g for CC and 34.56mg/g for EC. Therefore, it is shown that the early breakthrough term of 2-MIB and Geosmin was improved due to increased adsorbability. The low-molecular-weight NOM (500~2000Da) compounds were the most competitive, participating in direct competition with 2-MIB for adsorption site.

• Korean journal of food and cookery science
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• v.24 no.1
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• pp.11-15
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• 2008

In searching for yeast to be utilized as biocontrol agents, a single yeast strain was isolated from Camellia sinensis based on its morphological, cultural, physiological, and biochemical properties, as well as by molecular techniques. This single strain was pink to red in color and designated as strain JY-1. The effects of temperature, pH, NaCl concentration, and ethanol concentration on the growth of the JY-l strain were examined for the JY-1. Growth occurred at temperatures ranging from 20 to $35^{\circ}C$, and between pH 3.0 and 12.0, with optimal growth at $25-30^{\circ}C$ and pH 5.0. The yeast also grew in the presence of 0-2% (w/v) NaCl and 0-4% (v/v) EtOH. The isolate was further classified based on biochemical characteristics using the VITEK system. The biochemical data obtained using this system were similar to those of Rhodotorula glutinis/Rhodotorula mucilaginosa (exhibiting a 93% matching level). Molecular phylogenetic analysis based on l8S rDNA sequences indicated that the yeast represented a basidiomycetous species, and its highest degree of sequence similarity was with Rhodosporidium azoricum, strain JCM11251 (99%).

• Korean Journal of Microbiology
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• v.31 no.1
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• pp.9-16
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• 1993

Physicochemical characteristics of chlorosomes isolated from Chlorobium lirnicoh f.thiosulfirtc~pl~ilut~i NClB 8327 were analyzed by means of UV-Visible spectrophotometer and CD-spectrophotometer. The density of the isolated chlorosomes were estimated to be 1.05 (g/$cm^{3}$) by Percoll self gradient ultracentrifugation. Chlorosome consist of bacteriochlorophyll d and some chlorobactene, and little amounl of bacteriochlorophyll a. Chlorosome is stable from 0 to $80^{\circ}C$and alkaline solution (above pH 7.0). but unstable in illuminated condition. From these results. it is suggested that some proteins or lipids may be essential for the stabilization of chlorosomes in vivo.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.251-261
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• 2017

Initially, we screened 18 Aspergillus sojae-like strains from Aspergillus spp. isolated from meju (Korean traditional fermented soybean brick) according to their morphological characteristics. Because members of Aspergillus section Flavi are often incorrectly identified because of their phylogenetic similarity, we re-identified these strains at the morphological and molecular genetic levels. Fourteen strains were finally identified as A. sojae. The isolates produced protease and ${\alpha}-amylase$ with ranges of 2.66-10.64 and 21.53-106.73 unit/g-initial dry substrate (U/g-IDS), respectively, which were equivalent to those of the koji (starter mold) strains employed to produce Japanese soy sauce. Among the isolates and Japanese koji strains, strains SMF 127 and SMF 131 had the highest leucine aminopeptidase (LAP) activities at 6.00 and 6.06 U/g-IDS, respectively. LAP plays an important role in flavor development because of the production of low-molecular-weight peptides that affect the taste and decrease bitterness. SMF 127 and SMF 131 appeared to be non-aflatoxigenic because of a termination point mutation in aflR and the lack of the polyketide synthase gene found in other A. sojae strains. In addition, SMF 127 and SMF 131 were not cyclopiazonic acid (CPA) producers because of the deletion of maoA, dmaT, and pks/nrps, which are involved in CPA biosynthesis. Therefore, A. sojae strains such as SMF 127 and SMF 131, which have high protease and LAP activities and are free of safety issues, can be considered good starters for soybean fermentations, such as in the production of the Korean fermented soybean products meju, doenjang, and ganjang.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.176-185
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• 2016

Yeonsan Ogae has been known as supporting health and high efficacy of treatment. In recent days, as the efficacy of functional peptides has known, the optimization of oligo peptides production and its characteristics from Ogae legs has been performed. Response surface method was used to perform the optimizaion of enzyme hydrolysis. The range of processes was temperature ( 40, 50 and $60^{\circ}C$), pH( pH 6.0, 7.0 and 8.0 ), and enzyme( 1, 2 and 3% ). The degree of hydrolysis, amino acids, molecular weight of products were analyzed. The optimum process of enzyme hydrolysis were determined as temperature $58^{\circ}C$, pH 7.5, and enzyme concentration 3%. At optimum conditions, the degree of hydrolysis after 2 h reaction was 75-80%. The amino acid and were 168.131 mg/100 g, respectively. The molecular weight of products by using MALDI-TOF was ranged from 300 to 1,000 Da.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.631-634
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• 1995

Some structural characteristics of hot-water insoluble rice starch [3 varieties of Japonica type and 3 varieties of Tongil type(Japonica-Indica breeding type)]were investigated. The amylose contents of hot-water insoluble starches were 2.7-6.1%. The chain distributions of hot-water insoluble starches were composed of super long chain of above ${\overline{DP}}\;55$ (31.9-38.7%), B chain of ${\overline{DP}}\;40-50$ (12.3-18.0%) and A chain of ${\overline{DP}}\;10-20$ (48.5-50.4%). The chain distributions of hot-water insoluble starches and their ${\beta}-limit$ dextrin were difference between rice varieties and their were differ from those of amylopectin and their ${\beta}-limit$ dextrin. these result suggest that hot-water insolubility of rice starch was showed its characteristic on the varieties and it be responsible for the molecular structure of amylopectin.

• Elastomers and Composites
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• v.46 no.3
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• pp.251-256
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• 2011

Effect of poly(propylene-co-octene) as a compatibilizer in toughened polypropylene/ poly(ethylene-co-octene) (EOC) was investigated. The EOCs used were metallocene catalyzed commercial linear low density polyethylene and they are elastomeric materials. The poly(propylene-co-octene) was synthesized by metallocene catalyst in our laboratory to be used as a compatibilizer in PP/EOC blends. PP/EOC blends without compatibilizer shows very low mechanical properties in specimens with weldlines while incorporation of a compatibilizer significantly increases the mechanical properties of specimens with weldlines. However, compatibilized PP/EOC blends does not show increased impact property in a weldline free specimen and it is attributed to low molecular weight of the poly(propylene-co-octene) synthesized in present study. It is expected that the poly(propylene-co-octene) having increased molecular weight provides very good performance as an effective compatibilizer in toughened polypropylene/EOC blends.