• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.21-25
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• 1997

우수한 세라믹스 제조를 위해서는 작은 입자지름, 좁은 입도분포, 구형의 입자형태, dopant와 matrix가 균일한 고용체를 갖고, 응집입자가 없으며 고순도인 원료 분말의 제조가 선행되어야 한다. 이를 위하여 본 연구에서는 수열 합성법을 이용하여$\alpha$-Al$_2$O$_3$, $\alpha$-SiO$_2$, PZT, PSZT, BTO등의 미세분말을 제조하는 공정에서 반응온도, 광화제의 양과 종류, 반응시간, 출발물질의 양과 종류, 전처리공정, 교반공정 등이 평균입자지름과 결정성 및 입도분포에 미치는 영향을 조사하였다. 그결과 미세분말의 종류에 관계없이 반응온도, 반응시간, 성장기질의 농도, 종자결정의 농도 등이 증가할수록 평균입경은 커지며, 광화제의 농도가 증가할수록 평균 입자지름이 작아지고, 광화제의 농도가 종자결정의 농도가 증가할수록 입도분포가 좁아짐을 알 수 있었다. 특히 $\alpha$-SiO$_2$에 대해 수열합성실험으로부터 평균입자지름과 수열합성의 조업변수간의 특성방정식을 얻었다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.96-96
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• 2003

벌크 형태의 CaN 단결정 성장은 매우 곤란한 관계로 아직까지 관련 기술의 개발이 미흡한 실정이다 오랜 기간동안 승화 (sublimation)법으로 대구경 벌크 GaN 단결정을 성장시키고자 하는 노력이 지속되었지만 최근까지도 만족할 만한 결과가 보고되지 않고 있다. 본 논문에서는 종래의 방법과는 달리 출발물질로서 GaOOH 분말을 채택하고, 이를 NH$_3$ 분위기에서 가열 반응시켜 GaN 결정을 성장시켰다. 반응온도와 반응시간 및 NH$_3$ 유량 등의 성장조건에 따른 GaN 결정의 성장거동과 광학적 특성을 조사하였다. 원료인 GaOOH 분말 1g을 석영 용기에 담아 직경이 35mm인 석영 보호관에 위치시키고, 1000~l17$0^{\circ}C$의 온도에서 NH$_3$ 가스를 100~1000 sccm으로 공급하면서 96시간 동안 반응시켰다. 실험이 종료되면 전기로의 온도를 상온까지 냉각시킨 후 석영 보호관 내벽에 성장된 Ga 결정을 채집하였다. 이와 같이 채집된 결정의 형태와 크기를 광학현미경을 사용하여 조사하였고, 결정표면의 상태를 전자현미경을 사용하여 관찰하였다. 시료의 결정성을 알아보기 위하여 X선 회절 분석을 하였고, 저온에서의 광루미네센스 (PL; photoluminescence) 특성을 조사하였다.

• Annual Conference on Human and Language Technology
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• 2004.10d
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• pp.229-231
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• 2004

본 연구는 다(多)음절 한국어 단어재인에서의 어휘접근단위(unit of lexical access)를 알아보고자 했다. 이를 위해 Taft(1987)가 영어 어휘접근단위를 알아보고자 했을 때 사용한 실험 패러다임을 이용하였다. 실험 결과 반응시간에서는 조건간 통계적으로 유의미한 차이를 보이지 않았지만, BOSS 조건의 반응시간이 짧은 경향성을 보였고, 반응률에 있어서도 BOSS를 지지하는 결과를 보여주었다. 물론, 반응 오류가 많은 등 Taft(1987)의 패러다임을 한국어에 적용하기에 부적절했던 점이 있었지만, 적어도 다음절 단어 어휘접근 시 BOSS가 역할을 하고 있다는 것은 알아 볼 수 있었다.

• The Journal of the Korea Contents Association
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• v.22 no.2
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• pp.593-604
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• 2022

This study examines how auditors respond to labor investment inefficiency, specifically its impact on audit fees and audit hours. Using a sample of Korean firms listed on the Korea Stock Exchange from 2003 to 2018, our empirical results indicate that firms involved in inefficient investment in labor incur higher audit fees and audit hours. This implies that auditors consider inefficient labor investment to cause considerable business risk, thus requesting higher external audit fees to compensate for higher audit risk. Furthermore, auditors expend more time and effort while auditing those firms by expanding the audit procedures to reduce the audit risk to an acceptable level. Finally, this study provides empirical evidence on whether the investment inefficiency in labor, an important factor in firms' competitiveness, incur higher audit fees as well as audit hours.

• Membrane Journal
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• v.8 no.3
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• pp.170-176
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• 1998

A study on the bioconversion of soluble starch to cyclodextrin(CD) homologue by CGTase was performed in the membrane-enzyme reactor equipped with a dead-end type membrane module. in the batch reactor, the total conversion of soluble starch to CD homologue was decreased rapidly from a maximum value of 45 % with increasing reaction time due to the product inhibition and breakdown of CD homologue to the reducing sugars. However, in the membrane-enzyme reactor, the total conversion of soluble starch was maintained at a constant value of 35 % throughout the reaction, since the membrane(MWCO = 10,000) promptly separated CD homologue from the reaction mixture. After the macdon for 24 hr in the membrane-enzyme reactor using a 10 % soluble starch solution, the cumulative production amount of CD homologue was about 3.7 kg/m$^2$ at the operating pressure of 2 atm.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.05a
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• pp.178-180
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• 2001

본 혐기성 반응기와 호기성 반응기를 사용하여 염색폐수를 처리 할 경우 HRT 24~30시간의 경우 색도는 방류수 수질기준을 만족시킬 수 있으나 외관상 색도를 띄며, COD의 경우 배출수 허용기준을 만족시키기 어려우므로 전처리나 후처리로써 응집. 침전 공정, 오존 및 UV와 같은 고도산화공정이 필요하다고 사료되었다.

• Korean Journal of Food Science and Technology
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• v.47 no.3
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• pp.299-305
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• 2015

The Folin-Denis assay using the Folin-Ciocalteu (F-C) reagent has been commonly used for analyzing the total phenolic compound content in various food products. In the present study, the effects of proteins on the reactivity of the F-C reagent with different phenolic compounds were investigated. Bovine serum albumin (BSA) or skim milk proteins showed a concentration-dependent increase in color response in the Folin-Denis assay; these proteins decreased the color response of most phenolic compounds tested. The reactivity of phenolic compounds was significantly less pronounced in the presence of BSA and this interference was greater at higher concentrations of phenolic compounds. The reactivity of phenolic compounds with the F-C reagent was reduced significantly by their oxidation; the reaction of the oxidized products with the F-C reagent was more severely affected by BSA. The interfering effects in the Folin-Denis assay might be attributable to binding interactions of phenolic compounds with proteins.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.9-12
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• 1998

폴리에스테르계 고분자 중에서 폴리에틸렌테레프탈레이트(PET)는 우수한 기계적, 화학적 성질을 갖고 있어 섬유, 필름 및 산업용 자재로 널리 사용되었으나, 최근 PET보다 더욱 우수한 내열성 및 형태 안정성을 갖는 필름 재질이 요구되고 있다. 페닐기 대신 나프탈렌기가 있는 폴리에틸렌 나프탈레이트(PEN)는 PET의 이러한 점을 보완할 수 있으나 강직한 분자쇄와 높은 결정화도로 인해 가공성이 낮은 단점이 있다[1].

• Korean Journal of Food Science and Technology
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• v.49 no.5
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• pp.507-512
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• 2017

The physicochemical properties of maize starch sonicated at various amplitudes (100, 200, and 300 W) and times (10, 30, and 50 min) were examined. The amount of enzyme-susceptible starch increased marginally after sonication. Sonication increased the amount of oil absorbed in the starch although the degree of oil absorption decreased with an extension of the sonication time, implied that different types and extent of damages occurred. Scanning electron microscopy revealed that ultrasound sonication did not form pores on the surfaces, but caused damages such as depression and erosion. Pasting viscosity of starch decreased with an increase in the severity of sonication conditions because of the weakened polymer network. X-ray diffraction suggested that the crystalline domains in starch were not susceptible to sonication and were more resistance to degradation. Sonicated starch formed more pin-holes on the surfaces in the initial glucoamylase reaction; subsequently, as the reaction proceeded, porous starch with enlarged pores was formed and finally, disrupted granular fragments were observed.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.19-28
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• 2009

The acid mine drainage (AMD) and landfill leachates released into the subsurface environment can result in serious environmental problems like soil and groundwater contamination. The AMD and the leachates of landfill were known to contain many heavy metals. In this study, the author assessed the reactivity and ability of the FeS coated-ALC for the removal of contaminants (As, Cd, Cu, Pb, Ni, Zn, Al) in AMD and leachates in landfill. The synthetic nano-FeS and Autoclaved Lightweight Concrete (ALC) were used as reactive materials in the permeable reactive barriers(PRBs). The result of batch test indicated that synthetic nano-FeS can remove 99% of heavy metals for the 1hr of reaction time except for As and Ni(about 90%). However, the 80% of As and Ni was removed in column 1(FeS coated-ALC). The column 2(Ore FeS) removed more than 99% of heavy metals. The pH of the column 1 was increased from 3.51 to 6.39~6.50, and the pH with column 2 was increased from 3.51 to 9.20. As the result of this study, the author can surmise that the synthetic nano-FeS coated ALC will use as a very good reactive material of the PRBs to treat the contaminated groundwater with AMD and leachate of landfill.