• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.71-76
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• 2011

An efficient nucleophilic [$^{18}F$]fluorination has been studied to reduce byproducts and preparation time. Instead of conventional aqueous solution of $K_2CO_3-K_{222}$, several organic solution containing inert organic salts were used to release [$^{18}F$]fluoride ion and anion bases captured in the polymer cartridge, concluding that methanol solution is the best choice. Comparing to azeotropic drying process, one min was sufficient to remove methanol completely, resulting in about 10% radioactivity saving by reducing drying time. The polymer cartridge, Chromafix$^{(R)}$ (PS-$HCO_3$) was pretreated with several anion bases to displace pre-loaded bicarbonate base. Phosphate bases showed better results than carbonate bases in terms of lower basicity. tert-Butanol solvent used as a reaction media played another critical role in nucleophilic [18F]fluorination by suppressing eliminated side product. Consequent [$^{18}F$]fluorination under the present condition afforded fast preparation of reaction solution and high radiochemical yields (98% radio-TLC, 84% RCY) with 94% of precursor remained.

• 한국식품영양학회지
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• 제12권1호
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• pp.77-84
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• 1999

The purpose of this study is to establish a rapid preparation method of Dongchimi-juice having favor-able flavor and high antibacterial activity against undesirable bacteria in Naengmyon-broth by using high antibacterial strains of lactic acid bacteria Lactobacillus homohiochii B21 and leuconostoc mesenteroid-es subsp. mesenteroides C16 as Dongchimi starter. When the two strains of lactic acid bacteria were used as starter mixed culture was better than single culture in acid production and antibacterial activity. When starter was not inoculated in Dongchimi fermentation the numbers of Gram negatives and colifor-ms were remarkably increased in early phase and antibacterial activity could scarcely be detected. But when starter was inoculated the numbers of Gram negatives and coliforms were sharply decreased from early phase and antibacterial ctivity was high. When Dongchimi was made with heat sterilized mat-erials and starter there were no Gram negatives and coliforms and antibacterial activity was high. The antibacterial activity of starter inoculated Dongchimi was maximum in 2 days of fermentation at 2$0^{\circ}C$ and was scarcely detected in six days. In consideration of coliform counts antibacterial activity and the flavor of Dongchimi the preparation method in which all materials were heat treated at 8$0^{\circ}C$ for 15 min-utes and inoculated with mixed starter of the two strains and fermented for 2 days at 2$0^{\circ}C$ was thoug-ht to be good.

• Elastomers and Composites
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• 제40권2호
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• pp.128-135
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• 2005

전분/PVA 블렌드의 기계적 물성에 영향을 미칠 수 있는 인자들을 고려하여 최적화 조건을 조사하였다. 실험은 다구찌 방법에 기반을 둔 실험크기 27, 3수준, 13열의 $L_{27}(3^{13})$ 직교배 열표가 사용되었다. UTM과 인열 강도계를 통하여 인장강도, 파단신율, 초기탄성률, 인열강도를 측정하여 전분/PVA 블렌드의 제조 최적 조건을 결정하였다. 각 변수들의 분석을 바탕으로 각인자의 상호작용 효과가 결정되었다. $L_{27}(3^{13})$의 분석결과, 글리세롤과 요소가 4가지 기계적 물성의 증진에 가장 중요한 인자로 파악되었다.

• Steel and Composite Structures
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• 제32권5호
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• pp.559-569
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• 2019

The bond strength between composite laminates and concrete is a key factor that controls the behavior of concrete members strengthened with fiber reinforced polymer (FRP) sheets, which can be affected by several parameters such as thermal stresses and surface preparation. This article presents the result of an experimental study on the bond strength between FRP sheets and concrete at ambient temperature after specimens had been exposed to elevated temperatures of up to $200^{\circ}C$. For this purpose, 30 specimens of plain concrete with dimensions of $150{\times}150{\times}350mm$ were prepared. Three different conventional surface preparation methods (sandblasting, wire brushing and hole drilling) were considered and compared with a new efficient method (fiber implantation). Deformation field during each experiment was monitored using particle image velocimetry. The results showed that, the specimens which were prepared by conventional surface preparation methods, preserved their bond integrity when exposed to temperature below glass transition temperature of epoxy resin (about $60^{\circ}C$). Beyond this temperature, the bond strength and stiffness decreased significantly (about 50%) in comparison with control specimens. However, the specimens prepared by the proposed method displayed higher bond strengths of up to 32% and 90% at $25^{\circ}C$ and $200^{\circ}C$, respectively.

• Membrane and Water Treatment
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• 제13권4호
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• pp.191-199
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• 2022

In industrial production, the development of traditional polyamide nanofiltration (NF) membrane was limited due to its poor oxidation resistance, complex preparation process and high cost. In this study, a composite NF membrane with high flux, high separation performance, high oxidation resistance and simple process preparation was prepared by the method of dilute solution dip coating. And the sulfonated polysulfone was used for dip coating. The results indicated that the concentration of glycerin, the pore size of the based membrane, the composition of the coating solution, and the post-treatment process had important effects on the structure and performance of the composite NF membrane. The composite NF membrane prepared without glycerol protecting based membrane had a low flux, when the concentration of glycerin increased from 5% to 15%, the pure water flux of the composite NF membrane increased from 46.4 LMH to 108.2 LMH, and the salt rejection rate did not change much. By optimizing the coating system, the rejection rate of Na₂SO₄ and PEG1000 was higher than 90%, the pure water flux was higher than 40 LMH (60psi), and it can withstand 20,000 ppm.h NaClO solution cleaning. When the post treatment processes was adjusted, the salt rejection rate of NaCl solution (250 ppm) reached 45.5%, and the flux reached 62.2 LMH.

• 직업교육연구
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• 제36권4호
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• pp.1-20
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• 2017

이 연구는 대학생의 진로준비행동에 미치는 인지적, 심리적 선행요인을 확인하고 변인 간의 구조적 관계를 밝히고자 하였다. 먼저, 대학생의 성찰학습이 진로준비행동에 미치는 영향을 확인 한 후 성찰학습과 진로준비행동 사이에서 그릿의 매개효과를 검증하였다. 연구목적을 달성하기 위해 국내 4년제 대학에 재학 중인 대학생 중 진로와 취업준비에 비교적 관심이 많고 실제적으로 많은 노력을 기울이고 있는 3, 4학년 307명을 대상으로 설문조사를 실시하였다. 분석결과, 성찰학습(성찰, 비판적 성찰)은 그릿(흥미일관성, 노력지속성)과 진로준비행동(정보수집활동, 도구구비활동, 목표달성활동)의 모든 변인에서 유의한 정적 관계를 가지며, 무성찰학습(습관적 행동, 이해)은 주요 변인 모두에서 유의하지 않는 관계를 갖는다는 것을 검증하였다. 추가적으로 성찰학습은 진로준비행동에 직접적인 정적 영향을 미치고, 그릿은 성찰학습과 진로준비행동의 관계에서 매개효과가 있음을 확인하였다. 이러한 연구 결과를 통해 대학생의 진로준비행동 향상을 위하여 보다 원천적인 변인을 추가적으로 규명하고 확장하였으며, 대학 교육 현장에서 적용할 수 있는 진로 및 취업준비 교육프로그램 개발의 기초자료를 제공 했다는 것에 의의가 있다. 또한, 대학생 스스로가 주변 환경과 상황을 비판적으로 성찰할 수 있는 능력을 향상시키고 이를 지속적으로 노력하고 관심 과제에 대한 흥미를 유지하는 것이 중요함을 확인하였으며, 이를 위해 고등교육기관은 학생의 진로결정 및 취업과 관련한 보다 근본적이고 확장적인 실천 방법과 교육환경 제공이 중요함을 제언하였다.

• Animal cells and systems
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• 제3권1호
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• pp.73-78
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• 1999

Although there are several methods for the preparation of mitochondrial DNA (mtDNA) from mammalian tissues, most are relatively long ultracentrifugation or manipulations by a small-scale method. We escribed a rapid method for large-scale extraction of mtDNA from human placental and horse liver tissues. The method is based on the preparation and homogenization of tissues, urification of crude mitochondria by differential centrifugations and isolation of mtDNA by alkaline Iysis. It was improved from Pre-existing methods by replacing some steps with simpler ones and discarding many others. This method gives a high yield of pure mtDNA(approximately 1-5mg from one placenta; ca. 400-600 g wet weight), depending on its sources (fresh tissue gave better results than frozen one). The resulting mtDNA indicated that this method can yield mtDNA in sufficient purity and quantity to identify the direct restriction analysis on agarose gel, random-primed labeling as a probe, and end labeling. Therefore, the method is ideal for obtaining good mtDNA samples to conduct routine restriction fragment length polymorphism (RFLP) analyses of natural populations for genetic studies.

• 디지털융복합연구
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• 제12권8호
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• pp.493-499
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• 2014

본 연구는 베이비부머(실험집단 11명, 통제집단 12명)을 대상으로 하여, 생애설계 교육 프로그램의 효과성을 검증하는데 목적이 있다. 충남 A지역에서 주2회 각 2시간씩 총 36시간의 프로그램이 시행되었다. 그 결과 첫째, 실험집단 베이비부머의 프로그램 효과성 분석을 위해 사전-사후검사간의 Wilcoxon의 조합기호 순위검증법을 실시한 결과 실험집단 베이비부머는 노후준비의식에서 자원봉사준비 의식이 향상된 것으로 나타났고, 통제 집단은 사전-사후 유의미한 차이가 나타나지 않았다. 둘째, 프로그램의 만족도는 교육과정, 교육내용, 교육자료, 교육방법, 강사, 교육환경에 대한 만족도는 모두 5점 만점에 3.5점 이상으로 나타났다.

• 디지털융복합연구
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• 제18권5호
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• pp.89-98
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• 2020

본 연구의 목적은 대학생의 진로준비행동과 진로적응성의 관계에서 계획된 우연기술의 매개효과를 검증함으로써 진로적응성을 강화하기 위한 방안을 제시하는 것이다. 이를 위해 서울 소재 4년제 대학에 재학 중인 3, 4학년 학생 256명을 대상으로 수집된 자료를 회귀분석방법을 이용해 매개효과를 검증하였다. 연구결과 첫째, 대학생의 진로준비행동, 계획된 우연기술과 진로적응성 간에는 모두 통계적으로 유의미한 상관관계가 있는 것으로 확인되었다. 둘째, 대학생의 진로준비행동과 계획된 우연기술은 진로적응성에 정적인 영향을 미치는 것으로 나타났다. 셋째, 계획된 우연기술과 유연성을 제외한 계획된 우연기술의 모든 하위요인들이 진로준비행동과 진로적응성의 관계에서 부분 매개효과를 갖는 것으로 확인되었다. 이러한 연구결과를 토대로 대학생의 진로적응성 강화를 위하여 진로준비행동과 계획된 우연기술을 향상시킬 수 있는 방안에 대해 제언하였다.

• 복식문화연구
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• 제27권5호
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• pp.461-478
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• 2019

As the concept of "marriage age" gradually disappears, the consumption class of the wedding market includes not only X and Y generations but also Z generations, and each generation has its own characteristics as it is already known, and there are differences in the consumption. So this research analyzed age-related behavior differences in both awareness of and preparation for marriage. Three hundred sixteen unmarried Korean males and females comprised the study population and data was collected from March 5, 2019, to April 3, 2019. The SPSS Statistics 23.0 Package was used for analysis, specifically the functions of frequency, cross tabulation, factor analysis, chi-squared test, Cronbach's alpha, Duncans's new multiple range test (MRT), and analysis of variance (ANOVA). Marriage motivation was analyzed by three factors, and there were significant differences in two types. Marital involvement was analyzed by two factors, and both factors showed significant age-related differences. Concerns relating to marriage preparation were analyzed by four factors, and two varied according to respondent age. Regarding marriage preparation behaviors, the analysis revealed that the marriage preparation method appreciably differed between age groups. Our analysis also found significant age-related differences in "the main media usually used to acquire information" and "the paths preferred for acquiring information in preparing for marriage". We expect that study results will be useful for identifying new research directions, understanding the dimensions of the wedding industry, and developing related marketing strategies.