• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.8
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• pp.979-985
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• 2017

This study was carried out to investigate the production of ${\gamma}$-aminobutyric acid (GABA) by lactic acid bacteria and to manufacture GABA using rice bran extract-based optimum medium. Electrostatic spraying technology was used to add GABA into the cereals. The isolated Lactobacillus brevis CFM11 produced the highest GABA production up to a concentration of $2,002.93{\mu}g/mL$ when cultivated in MRS broth containing 0.8% monosodium glutamate (MSG). The production level of GABA was $585.80{\mu}g/mL$ in rice bran extract containing 0.4% MSG, 2% sucrose, 1% skim milk, and 0.2% magnesium sulfate. After electrostatic spraying of the cultured suspension onto rice, GABA concentration reached $228.10{\mu}g/g$ while untreated rice reached $32.23{\mu}g/g$. These results demonstrate that rice bran extract can be an economic commercial medium for GABA production as a substitute for MRS broth. This study demonstrates the novel application of electrostatic spraying of GABA into cereal products for the first time.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.11-20
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• 1994

GaAs and AlGaAs epi-layers were grown on semi-insulating (100) GaAs substrate by molecular beam epitaxy (MBE) and their electrical and optical properties have been investigated by several measurements. In undoped GaAs, the p-type GaAs layers with the good surface morphology were obtained under the growth conditions of the substrate temperatures ranging from 570 to $585^{\circ}C$ and the $As_4$/Ga ratios from 17 to 22. In the samples with the growth rates of the ranges of $0.9~1.1 {\mu}m/h$, the impurity concentrations were in the ranges of $1.5{\times}10^{14}~5.6{\times}10^{14}cm^{-3}$ with the Hall mobilities of $590~410cm^2/V-s$. In the Si-doped GaAs, the n-type GaAs layers with low electro trap, only two hole deep levels were observed with uniform doping profiles (<1%). AlGaAs layers with good surface morphology and crystallinity were grown under an optimum condition of the substrate temperature, $600^{\circ}C $. 8 deep level defects were observed between 0.17~0.85eV in undoped AlGaAs layers.

• Korean Journal of Food Science and Technology
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• v.43 no.1
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• pp.30-38
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• 2011

Effects of depolymerization treatments of a carbohydrase mixture (CM), ultrasound, and irradiation on the physical properties of defatted mustard meal-based edible films (DMM films) were investigated. DMM hydrocolloids were added to CM (0.42% (w/w solution)), treated by ultrasound (500-700 W, 10-30 min) or ${\gamma}$-ray (40-100 kGy) to prepare film-forming solutions. Films were formed by drying. The CM treatment at 0.42% (w/w), pH 5.5, and 40-$50^{\circ}C$ with a 0.5 hr incubation time resulted in the highest colloidal stability in the film-forming solution. The depolymerization treatments did not dramatically change the water vapor permeability of the films. The solubility of the film decreased up to 53.1% by the CM treatment. The ultrasound treatment (700 W-30 min) decreased tensile strength and elongation. The ultrasound treatment (600 W-20 min) resulted in more compact and uniform structures of the films. Flavor profiles were differentiated by the power level and the time of the ultrasound treatment.

• Journal of Food Hygiene and Safety
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• v.30 no.4
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• pp.350-358
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• 2015

This study was designed to evaluate the sanitary characteristics of sea water in a part of the south coast, Korea and to check the seawater which is in compliance with the recommended bacteriological criteria for shellfish cultivation. The samples of sea water were collected at 14 sampling stations established in the survey area between March 2014 and October 2014. Food poisoning caused by seafood consumption is often associated with pathogenic microorganisms originated from fecal contamination. Therefore, fecal coliform is very important criteria for evaluating the safety of fisheries in coastal areas. The range of geometric mean (GM) and the estimated 90th percentile values of total coliform were 4.1~83.1 MPN/100 mL, and 11.7~834.1 MPN/100 mL, respectively. The GM and the estimated 90th percentile values of fecal coliform were 2.5~22.7 MPN/100 mL and 2.5~170.0 MPN/100 mL, respectively. Therefore, the bacteriological safety of seawater at this shellfish-growing area met with the Korean Shellfish Sanitation Program (KSSP) criteria for a growing area. However, the values are seasonally exceed the KSSP criteria, suggesting that the monitoring and evaluation of seawater quality is very important in shellfish-growing area.

• Korean Journal of Materials Research
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• v.20 no.4
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• pp.210-216
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• 2010

This paper investigates the dependence of a-Si:H/c-Si passivation and heterojunction solar cell performances on various cleaning processes of silicon wafers. It is observed that the passivation quality of a-Si:H thin-films on c-Si wafers depends highly on the initial H-termination properties of the wafer surface. The effective minority carrier lifetime (MCLT) of highly H-terminated wafer is beneficial for obtaining high quality passivation of a-Si:H/c-Si. The wafers passivated by p(n)-doped a-Si:H layers have low MCLT regardless of the initial H-termination quality. On the other hand, the MCLT of wafers incorporating intrinsic (i) a-Si:H as a passivation layer shows sensitive variation with initial cleaning and H-termination schemes. By applying the improved cleaning processes, we can obtain an MCLT of $100{\mu}sec$ after H-termination and above $600{\mu}sec$ after i a-Si:H thin film deposition. By adapting improved cleaning processes and by improving passivation and doped layers, we can fabricate a-Si:H/c-Si heterojunction solar cells with an active area conversion efficiency of 18.42%, which cells have an open circuit voltage of 0.670V, short circuit current of $37.31\;mA/cm^2$ and fill factor of 0.7374. These cells show more than 20% pseudo efficiency measured by Suns-$V_{oc}$ with an elimination of series resistance.

• The Korean Journal of Financial Management
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• v.12 no.1
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• pp.33-56
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• 1995

본(本) 연구(硏究)는 자본구조이론과 전통적 연구에서 제시된 변수를 통합하고 횡단면(橫斷面) 요인(要因)과 시계열(時系列) 요인(要因)을 결합하여 우리나라의 자본구조결정 요인을 식별할 수 있는 이론적(理論的) 모형(模型)을 제시하여, 또한 제시된 모형을 한국증권시장(韓國證券市場)의 자료(資料)를 이용하여 실증적(實證的)으로 분석(分析)하였다. 그리고 실증적 분석에는 횡단면(橫斷面) 자료(資料)와 시계열(時系列) 자료(資料)를 결합하는 패널자료추정법(資料推定法)을 사용하였다. 본(本) 연구(硏究)에서 제시된 자본구조이론(資本構造理論)과 관련된 결정 요인으로는 기업(企業)의 성장기(成長機)을, 내부주주(內部株主)의 지분율(持分率) 그리고 내부주주수(內部株主數)의 비율 등을, 전통적 횡단면 요인으로는 경영위험(經營危險), 자산구성(資産構成), 수익성(收益性), 기업규모(企業規模) 등을, 그리고 전통적 시계열 요인으로는 법인세율(法人稅率)과 물가수준(物價水準) 등을 제시하였다. 본(本) 연구(硏究)에서 다루는 실증분석기간은 1981년 1월부터 1990년 12월까지의 10년간이었으며, 추출된 표본기업(標本企業)의 수(數)는 104개사이다. 실증적 분석결과, 본(本) 연구(硏究)에서 제시된 설명변수들이 자본구조(資本構造)의 변동(變動)을 49.91%정도 설명하고 있으며 설명변수 중 기업(企業)의 성장기회(成長機會), 내부주주(內部株主)의 지분을, 경영위험(經營危險), 수익성(收益性), 기업규모(企業規模), 물가수준(物價水準) 등은 자본구조의 결정 요인으로 통계적인 의미를 갖는 변수로 밝혀졌으며 회귀계수(回歸係數)의 부호도 기대하였던 바와 일치하고 있다. 질산으로 처리된 것이 컸고 0.75 M과 1.0 M의 질산을 사용했을 때는 작음이 확인되었다. 이상의 실험결과들로부터 친수성인 $NH_4Y$형 제올라이트를 소수성의 것으로 변환시키기 위한 수증기의 온도는 $500^{\circ}C$와 $600^{\circ}C$가, 그리고 질산의 농도는 0.5 M이 적합한 것으로 결론지을 수 있고, 이와 같은 결론은 BET비표면적과 TPV값과 같은 경향을 보인 벤젠과 톨루엔의 흡착용량측정결과로 입증되었다. 탈알루미늄된 제올라이트들의 수분에 대한 Si/Al비와 흡착용량은 각각 높은 농도의 질산으로 처리된 것일수록 증가하고 감소하여 소수성이 증가함을 나타내었다.(不適合性)이 나타났다. 본 연구는 기존의 기대수익률(期待收益率) 위주의 요일효과(曜日效果) 분석에서 주식수익률(株式收益率)의 분산(分散) 즉, 변동성(變動性)에 촛점을 두어 분석하였으며, 이는 투자자의 정확한 위험측정(危險測定)수단의 제공이라는 면에서 의의(意義)가 있을 것으로 생각된다.據金) 운용(運用)에 관한 정책수립시(政策樹立時) 금융선진국(金融先進國)의 증거금(證據金) 정책운용(政策運用)을 통한 시장관리(市場管理) 경험(經驗)을 어느 정도 참고할 수 있음을 시사한다고 할 것이다. 한다. 실증분석결과는 본문의 <표 1>에 제시되어 있으며 그 내용을 간략하게 요약하면 다음과 같다. (A) 실증분석모형 : 본 연구에서는 다기간 자산가격결정모형중에서 대표적인 Lucas (1978)모형을 직접 사용한다. $$1={\beta}\;E_t[\frac{U'(C_{t+1})\;P_t\;s_{t+1}}{U'(C_t)

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1222-1229
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• 2012

The total area of a reclaimed tidal soil distributed on the south-west coast is approximately 156,600 ha, and the soil contains high contents of sand and silt as well as highly saline. Most of the reclaimed tidal soils are used as a paddy due to bad permeability and high groundwater table, resulting in easy accumulation of salts on the soil surface by capillary rise. Therefore, resalinization may occur because of rise of groundwater table after desalinization. The researches related to the reclaimed tidal soil mainly focused on desalinazation while most of the researches completed were limited to yields of crop based on desalinazation. pH of old reclaimed tidal soil is neutral or less than 7 while that of newly developed reclaimed tidal soils is greater than 7, that cause N-fertilizer to be volatile as ammonia. Thus, the physical and chemical properties should be investigated to be used as an arable upland instead of a paddy soil due to change in government policy. We need to develop measures to make soils grow crops normally by identifying problems related to reclaimed tidal soils.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.221-237
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• 2005

For developing the site-specific fertilizer management strategies of crop, it is essential to know the spatial variability of soil factors and to assess their influence on the variability of crop growth and yield. In 2002 and 2003 cropping seasons within-field spatial variability of rice growth and yield was examined in relation to spatial variation of soil properties in the· two paddy fields having each area of ca. $6,600m^2$ in Suwon, Korea. The fields were managed without fertilizer or with uniform application of N, P, and K fertilizer under direct-seeded and transplanted rice. Stable soil properties such as content of clay (Clay), total nitrogen (TN), organic mater (OM), silica (Si), cation exchange capacity (CEC), and rice growth and yield were measured in each grid of $10\times10m$. The two fields showed quite similar spatial variation in soil properties, showing the smallest coefficient of variation (CV) in Clay $(7.6\%)$ and the largest in Si $(21.4\%)$. The CV of plant growth parameters measured at panicle initiation (PIS) and heading stage (HD) ranged from 6 to $38\%$, and that of rice yield ranged from 11 to $21\%$. CEC, OM, TN, and available Si showed significant correlations with rice growth and yield. Multiple linear regression model with stepwise procedure selected independent variables of N fertilizer level, climate condition and soil properties, explaining as much as $76\%$ of yield variability, of which $21.6\%$ is ascribed to soil properties. Among the soil properties, the most important soil factors causing yield spatial variability was OM, followed by Si, TN, and CEC. Boundary line response of rice yield to soil properties was represented well by Mitcherich equation (negative exponential equation) that was used to quantify the influence of soil properties on rice yield, and then the Law of the Minimum was used to identify the soil limiting factor for each grid. This boundary line approach using five stable soil properties as limiting factor explained an average of about $50\%$ of the spatial yield variability. Although the determination coefficient was not very high, an advantage of the method was that it identified clearly which soil parameter was yield limiting factor and where it was distributed in the field.

• Journal of Nutrition and Health
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• v.20 no.6
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• pp.395-404
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• 1987

A nutritional quality and rancidity of marketed korean traditional foods were assessed. That is, basic chemical analysis were done in Galbi-tang, Sullung-tang, Pibimbap, Pulkogi and Naeng Myon. Ca and P for the Galbi-tang and Sulung-tang and vitamin C for the Pibimbap were analyzed. Chemical analysis were done in Gangjung 4, Sanja 1, Parksan 6, Yoomilkwa, 4 out of korean traditional cookies. Amounts of energy and protein in Galbi -tang and protein and Ca in Sullung -tang are more than the recommended allowance at ta meal. Amounts of Ca in Galbi-tang and energy in SUllung-tang are less than the recommended . The amounts of energy and protein in Pibimbap, Pullkigi and Naeng Myon Except protein in Pullkogi are short of the recommended at a meal. And amounts of vitamin C in Pibimbap are short of the recommended, too. The content of carbohydrate in Korean traditional cookies is the highest one comparing to others. Contents of crude fat in Gangjung Parksan and Dasik which are made up of sesame, black sesame and pine nuts are higher than that of other Korean traditional cookies. Acid value and peroxide value in all Gangjung, Yoomilkwan and Sanja except the peroxide value in one Sanja product, are not in the excess of standard of peroxide value and acid value. The standard are 600meq/kg and 3 for peroxide value and acid value respectively in oil treated foods.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.987-996
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• 2009

Aspergillus niger GH1 previously isolated and identified by our group as a wild tannase producer was grown under solid-state (SSC) and submerged culture (SmC) conditions to select the enzyme production system. For tannase purification, extracellular tannase was produced under SSC using polyurethane foam as the inert support. Tannase was purified to apparent homogeneity by ultrafiltration, anion-exchange chromatography, and gel filtration that led to a purified enzyme with a specific activity of 238.14 IU/mg protein with a final yield of 0.3% and a purification fold of 46. Three bands were found on the SDS-PAG with molecular masses of 50, 75, and 100 kDa. PI of 3.5 and 7.1% N-glycosylation were noted. Temperature and pH optima were 600e and 6.0 [methyl 3,4,5-trihydroxybenzoate (MTB) as substrate], respectively. Tannase was found with a $K_M$ value of $0.41{\times}10^{-4}M$ and the value of $V_{max}$ was $11.03{\mu}$moL/min at $60^{\circ}C$ for MTB. Effects of several metal salts, solvents, surfactants, and typical enzyme inhibitors on tannase activity were evaluated to establish the novelty of the enzyme. Finally, the tannase from A. niger GH1 was significantly inhibited by PMSF (phenylmethylsulfonyl fluoride), and therefore, it is possible to consider the presence of a serine or cysteine residue in the catalytic site.