• 대한기계학회논문집
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• 제17권1호
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• pp.120-130
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• 1993

본 연구에서는 니켈의 가공시 나타나는 공구의 마멸에 대한 정량화 및 절삭변 수와의 연관성에 대한 연구는 그 자체가 마멸에 대한 데이터 베이스 측면에서 중요하 고, 이러한 접근방법으로는 연구가 거의 이루어지지 않았다는 측면에서도 큰 의미를 갖는다. 본 연구는 특히 경도가 큰 공구인 CBN, 소결 다이아몬드(poly crystal dia- mond 이하 PCD), 단결정 다이아몬드(single crystal diamond 이하 SCD)공구를 사용하 여 니켈의 절삭에서 나타나는 공구의 마멸에 대한 분석을 선행한 후 수집한 정보로부 터 절삭속도, 이송, 절삭깊이 및 공구의 nose반경이 공구의 마멸 및 표면의 성상(su- rface quality)에 미치는 영향에 대하여 고찰하였고 절삭조건의 변화에 따라 마멸에 대한 예상 곡선을 구하였다.

• 공학교육연구
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• 제13권4호
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• pp.87-92
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• 2010

공학인증의 여러 인증 요건들 중의 하나인 프로그램 학습성과에 대한 평가와 분석등은 평가도구 개발이라는 관점에서만 보더라도 지속적인 연구가 필요한 분야이다. 본 연구에서는 본 프로그램 학습성과 평가체제에서 제시한 절차대로 졸업시험, 에세이, 종합설계, 그리고 공인 영어점수를 평가도구로 활용한 프로그램 학습성과 평가결과와 교과목 학습성과를 이용한 프로그램 학습성과 결과를 비교하였다. 4가지 평가도구를 활용한 프로그램 학습성과 평가는 2010년 심화과정 졸업자 15명을 대상으로 하였고, 교과목 학습성과를 이용한 프로그램 학습성과는 2009년 1학기와 2학기에 개설하여 운영한 교과목을 이용하였다. 두가지 평가결과 모든 학습성과 평가에서 큰 차이를 보이지 않는 것으로 보아 교과목 학습성과를 이용한 프로그램 학습성과도 프로그램에서 활용할 수 있는 실질적인 프로그램 학습성과 평가방법 중 하나임을 알 수 있었다.

• 대한화학회지
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• 제52권3호
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• pp.315-321
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• 2008

포스터는 시각적 이미지와 약간의 언어를 사용하여 자신의 생각을 다른 사람과 의사소통하는 도구이다. 모든 학문 분야에는 독특한 의미로 구성원들 사이에 공유되는 기호가 있다. 따라서 화학자나 화학을 배우는 학생들은 특징적인 화학적 기호(코드)를 통해 의사소통할 것이다. 대한화학회에서는 2004년부터 전국의 학생들을 대상으로 화학 포스터 그리기 대회를 개최하고 있다. 2004년과 2005년에 3000여 점의 포스터가 출품되었고 150여 포스터가 수상작으로 선정되었다. 수상작은 초등학교, 중학교, 고등학교 급별로 구분되었다. 이 연구는 학생들의 포스터에 사용된 화학적 코드를 조사하였다. 포스터의 시각적 요소와 언어적 요소를 분석한 결과, 액체, 실험기구, 눈금, 화학의 언어, 과학자, 지구와 환경, 주변의 사물 등 7가지 화학의 코드를 찾을 수 있었다. 그리고 화학의 코드에 대해 학교급별 차이, 수상작과 비수상작의 차이, 연도별 차이 등을 조사하였다. 또한 이러한 결과에 대한 교육적 함의를 논의했다.

• 공학교육연구
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• 제13권5호
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• pp.55-60
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• 2010

Chemistry laboratory class was produced for senior high school freshmen with the cooperation of university staffs, high school teachers and the university students. Although the students who will take the lab class are senior high school freshmen, we decided to prepare four experiments that are simple and have highly visible reactions or transformation. That is, 1) Water purification, 2) Surface modification, 3) Briggs-Rauscher reaction, and 4) Polymer synthesis and characterization. After the safety guideline and experiment instructions by the faculty staffs, two teaching assistants (TAs) supervised each experiment. Since taking a direct part in it will provide stronger impact than only being one who is just watching the experiment, all experiments contained some process that the high school students must handle the reagents, tools or the equipment, by themselves. Although, the operation performed by the students was limited to a series of simple actions, the various unique phenomena presented by the experiments impressed the students. The lab class was fruitful not only for high school students, but also good for university students. The lab class provided good opportunity for them to improve the abilities to teach and guide someone.

• Environmental Engineering Research
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• 제23권4호
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• pp.474-484
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• 2018

The cleaning efficiency of reverse osmosis (RO) membranes inevitably fouled by organic foulants depends upon both chemical (type of cleaning agent, concentration of cleaning solution) and physical (cleaning time, flowrate, temperature) parameters. In attempting to determine the optimal procedures for chemical cleaning organic-fouled RO membranes, the design of experiments concept was employed to evaluate key factors and to predict the flux recovery rate (FRR) after chemical cleaning. From experimental results and based on the predicted FRR of cleaning obtained using the Central Composite Design of Minitab 17, a modified regression model equation was established to explain the chemical cleaning efficiency; the resultant regression coefficient ($R^2$) and adjusted $R^2$ were 83.95% and 76.82%, respectively. Then, using the optimized conditions of chemical cleaning derived from the response optimizer tool (cleaning with 0.68 wt% disodium ethylenediaminetetraacetic acid for 20 min at $20^{\circ}C$ with a flowrate of 409 mL/min), a flux recovery of 86.6% was expected. Overall, the results obtained by these experiments confirmed that the equation was adequate for predicting the chemical cleaning efficiency with regards to organic membrane fouling.

• Environmental Analysis Health and Toxicology
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• 제24권2호
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• pp.95-105
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• 2009

Chemical Ranking and Scoring (CRS) system is a useful tool to screen priority chemicals of large body of substances. The relative ranking of chemicals based on CRS system has served as a decision-making support tools. Exposure potential and toxicity are significant parameters in CRS system, and there are differences in evaluating those parameters in each CRS system. In this study, the parameters of exposure potential, human toxicity, and ecotoxicity were extensively compared. In addition the scoring methods in each parameter were analyzed. The CRS systems considered in this study include the CHEMS-1 (Chemical Hazard Evaluation for Management Strategies), SCRAM (Scoring and Ranking Assessment Model), EURAM (European Union Risk Ranking Method), ARET (Accelerated Reduction/Elimination of Toxics), and CRS-Korea. An comparative analysis of the several CRS systems is presented based on their assessment parameters and scoring methods.

• The Plant Pathology Journal
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• 제24권3호
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• pp.245-268
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• 2008

The outcome of plant-pathogen interactions is influenced significantly by endogenous small molecules that coordinate plant defence responses. There is currently tremendous scientific and commercial interest in identifying chemicals whose exogenous application activates plant defences and affords protection from pathogen infection. In this review, we provide a survey of compounds known to induce disease resistance in plants, with particular emphasis on how each compound was originally identified, its putative or demonstrated mechanism of defence induction, and the known biological target(s) of each chemical. Larger polymeric structures and peptides/proteins are also discussed in this context. The quest for novel defence-inducing molecules would be aided by the capability for high-throughput analysis of candidate compounds, and we describe some issues associated with the development of these types of screens. Subsequent characterization of hits can be a formidable challenge, especially in terms of identifying chemical targets in plant cells. A variety of powerful molecular tools are available for this characterization, not only to provide insight into methods of plant defence activation, but also to probe fundamental biological processes. Furthermore, these investigations can reveal molecules with significant commercial potential as crop protectants, although a number of factors must be considered for this potential to be realized. By highlighting recent progress in the application of chemical biology techniques for the modulation of plant-pathogen interactions, we provide some perspective on the exciting opportunities for future progress in this field of research.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.48-54
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• 2008

A putative ${\omega}$-aminotransferase gene, cc3143 (aptA), from Caulobacter crescentus was screened by bioinformatical tools and overexpressed in E. coli, and the substrate specificity of the ${\omega}$-aminotransferase was investigated. AptA showed high activity for short-chain ${\beta}$-amino acids. It showed the highest activity for 3-amino-n-butyric acid. It showed higher activity toward aromatic amines than aliphatic amines. The 3D model of the ${\omega}$-aminotransferase was constructed by homology modeling using a dialkylglycine decarboxylase (PDB ID: 1DGE) as a template. Then, the ${\omega}$-aminotransferase was rationally redesigned to increase the activity for 3-amino-3-phenylpropionic acid. The mutants N285A and V227G increased the relative activity for 3-amino-3-phenylpropionic acid to 3-amino-n-butyric acid by 11-fold and 3-fold, respectively, over that of wild type.

• 한국표면공학회지
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• 제55권6호
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• pp.319-327
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• 2022

Ion exchange membranes have been developed from laboratory tools to industrial products with significant technical and trade impacts in the last 70 years. Today, ion exchange membranes are successfully applied for water and energy for different electro-membrane processes. Hydrogen could be produced by electrochemical water splitting using renewable energy, for example, solar, biomass, geothermal and wind energy. This review briefly summarizes the recent studies reporting the state-of-the-art anion-exchange membrane water electrolysis, especially focusing on the enhancement of the durability of anion-exchange membranes. Anion-exchange membrane water electrolysis could be used as inexpensive non-noble metal electrocatalysts that are capable of producing low cost of hydrogen. However, the main challenge of anion-exchange membrane water electrolysis is to increase the performance and durability. In this mini review, the limiting factors of the durability and the technology enhancing the durability will be discussed for anion exchange membrane water electrolysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1483-1486
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• 2004

Purpose of this paper is to accummulate database of automotive steel sheet from mild steel to high strength steel in cold rolled steel sheets. Physical properties, mainly mechanical properties, of steel sheet are tested and all data are arranged to one sheet. Methods of test are composed of FLD, tensile strength test, chemical composition, surface roughness and product conditions. Finally this database will be helpful to automotive body designers and die designers to design automotive body parts and tools in a material point of view.