• 분석과학
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• 제33권1호
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• pp.23-32
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• 2020

Methamphetamine (MA) is the most common and available drug of abuse in Korea and its primary metabolite is amphetamine (AP). Detection of AP derivatives, such as MA, AP, phentermine (PT), MDA, MDMA, and MDEA by the use of immunoassay screening is not reliable and accurate due to cross-reactivity and insufficient specificity/sensitivity. Therefore, the analytical process accepted by most urine drug-testing programs employs the two-step method with an initial screening test followed by a more specific confirmatory test if the specimen screens positive. In this study, a gas chromatography-mass spectrometric (GC-MS) method was developed and validated for confirmation of MA and AP in human urine. Urine sample (500 µL) was added with N-isopropylbenzylamine as internal standard and ethyl chloroformate as a derivatization reagent, and then extracted with 200 µL of ethyl acetate. Extracted samples were analysed with GC-MS in the SIM/ Scan mode, which were screened by Cobas c311 analyzer (Roche/Hitachi) to evaluate the efficiency as well as the compatibility of the GC-MS method. Qualitative method validation requirements for selectivity, limit of detection (LOD), precision, accuracy, and specificity/sensitivity were examined. These parameters were estimated on the basis of the most intense and characteristic ions in mass spectra of target compounds. Precision and accuracy were less than 5.2 % (RSD) and ±14.0 % (bias), respectively. The LODs were 3 ng/mL for MA and 1.5 ng/mL for AP. At the screening immunoassay had a sensitivity of 100% and a specificity of 95.1 % versus GC-MS for confirmatory testing. The applicability of the method was tested by the analysis of spiked urine and abusers' urine samples.

• 한국건설관리학회논문집
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• 제16권2호
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• pp.38-45
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• 2015

건설위험관리 프로세스의 위험분석단계는 정성적 및 정량적 위험분석단계로 세분화되는데, 정성적 위험분석이 주된 역할을 하고 정량적 위험분석은 보조적인 역할을 담당한다. 그런데 이제까지 정성적 위험분석단계에서 위험도를 계량화하는 방법으로 적용되어온 위험도 산정 공식은 발생확률과 영향을 단순히 곱하는 식으로서 결과 값들은 저위험도에 편중된 분포를 나타낸다. 이에 대한 대안으로 고위험도에 편중되는 산정 공식이 제안되었으나, 위험도 분포가 저위험도 또는 고위험도에 편중하게 될 경우 대부분의 자연현상이 정상분포에 가깝다는 통계학적인 일반논리에 부합되지 않는다. 본 연구에서는 위험도의 분포가 중앙에 집중되는 새로운 위험도 산정방법을 제안하고자 한다. 이를 통해 위험도 분포가 자연현상의 정상분포와 유사한 형식으로 표현됨으로써 위험에 대응하는 수준이 고위험도 또는 저위험도에 치우지지 않고 중간위험도에서 합리적으로 선택될 수 있게 하고자 한다. 나아가 위험도 산정방법에 대한 추가적인 선택사항을 제공함으로써 위험분석 방법의 융통성과 합리성을 향상시키는데도 일조하고자 한다.

• 분석과학
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• 제34권2호
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• pp.68-77
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• 2021

Cannabis is one of the most abused drugs in Korea. The main psychoactive component in cannabis, Δ9-tetrahydrocannabinol, is metabolized to 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) and THCCOOH-glucuronide (THCCOOH-glu) in the human liver, whereby the amount of THCCOOH-glu found in urine is twice as high as that of THCCOOH. The analytical process adapted by the majority of urine drug-testing programs involves a two-step method consisting of an initial immunoassay-based screening test followed by a confirmatory test if the screening test result is positive. In this study, a qualitative gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the detection of THCCOOH in human urine, where THCCOOH-glu was converted into THCCOOH by alkaline hydrolysis. For purification of the urine extract prior to instrumental analysis, high-speed centrifugation was used to minimize interference. In addition, an injection-port derivatization method using ethyl acetate and N,O-bis(trimethylsilyl)-trifluoroacetamide containing 1 % trimethylchlorosilane was employed to reduce the time required for derivatization, and an aliquot of the final solution was injected into the GC-MS. The method was validated by measuring the selectivity, limit of detection (LOD), and repeatability. The sensitivity, specificity, precision, accuracy, Kappa, F-measure, false positive, and false negative rate were determined by comparing the GC-MS results with those obtained using the immunoassay. The LOD was determined to be 0.32 ng/mL, while the repeatability was within 9.1 % for THCCOOH. Furthermore, a comparison study was carried out, whereby the screening immunoassay exhibited a sensitivity of 86.4 % and a specificity of 100 % compared to GC-MS. The applicability of the developed method was examined by analyzing spiked urine and forensic urine samples obtained from suspected cannabis abusers (n = 221).

• 한국과학교육학회지
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• 제25권4호
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• pp.526-532
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• 2005

본 연구는 '힘과 운동'에 관한 정량적, 정성적 문제에 따른 문제해결과정을 분석하여 어떤 차이가 있는지를 알아보고자 실시되었다. 본 연구의 대상은 여자고등학교 1학년 학생 8명이었다. 이들은 문제해결에 필요한 내용지식을 보유하고 있는 학생들이었다. 선행 지식검사와 정량적 문제 3개와 정성적 문제 3개로 구성된 본검사를 사용하였다. 연구결과, 정량적 문제에서는 계획단계의 시간비율이 정성적 문제에 비해 더 높고 총 소요시간도 길게 나타났으며, 해결단계의 반복횟수도 더 많았다. 정량적 문제에서 해결에 성공하는 정도는 정성적 문제에서 별 차이가 없었고, 전략사용에도 차이가 없었다. 학생들은 평소 물리학습에서 정량적 문제를 많이 접하므로 수식과 공식을 사용하여 문제 푸는 일에 익숙해 있고, 수식과 공식에 의한 결과를 더 신뢰해서 정성적 문제를 정량적으로 해결하려는 경향이 있었으며, 정성적 문제 보다 정량적 문제를 더 선호하였다.

• 대한인간공학회지
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• 제12권2호
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• pp.29-43
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• 1993

This paper presents a conceptual approach to convert customer requirements expressed in ordinary language into a form of qualitative and quantitative functions for developing new products. This approach attempts to combine the concepts of the value engineering and the Kansei engineering. It emphasizes that customer require- ments should be interpreted and reflected on the design of new product. Specific are discussed for extracting subjective requirements and transforming them into qualitative and quantitative functions for product design. This approach is expected to provide the product designer with a systematic efficient tool for incorporating subjective requirements into a product design.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.142-148
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• 1993

Recectly, development of expert system utilizing the domain specific knowledge focuses upon the machining operations. This paper describes an expert system for selecting the optimum grinding wheel based on the Analytic Hierarchy Process and Fuzzy Logic. Knowledge-base, in this system, for selecting of grinding wheel is designed to appling the knowhow and experience knowledge of skilled hands. In this paper, firstly determination method of fuzzy membership function utilizing the qualitative knowledge, and then selection of the optimum wheel from among the available components according to Saaty's priority rule are described. Lastly,some implementation results are suggested.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.148-155
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• 2001

A disassembility assessment has mostly depend on the subjective decision making from the qualitative element. The work of disassembly is already classified with given disassemble points from the symbolic chart method. It is not useful in the practical assessment because it is not specified. The new method of design for disassembility assessment(DFDA) is practical to introduce the fuzzy number as the conversion of quantitative element from qualitative. It is appled to air-cleaner of passenger-vehicle for the usefulness.

• 대한통합의학회지
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• 제2권4호
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• pp.83-90
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• 2014

Purpose : PBL is a teaching method to learn problem-solving process. Present study was to investigate the predictors of academic achievement when PBL is applied to students of physical therapy. Method : We Performed in-depth interviews and analyzed using the qualitative analysis by randomly assigning 5 of twenty four students who attended the class. Result : The results are classified into two categories and six sub-subjects. Based on two system of classification, PBL showed the learning effect through problem-solving methods because students directly participated in these processes. Also, students need to clearly comprehend communication method and decision-making process in order to progress the class smoothly. Conclusion : Therefore, futher studies will be continuously needed on how we apply PBL to various curriculums of physical therapy.

• 품질경영학회지
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• 제24권1호
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• pp.126-136
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• 1996

In multi-item production system, GT(Group Technology) is used effectively in order to cluster various parts into groups. GT is based on clustering parts which have similar features, and these features are classified into two properties, namely crisp(quantitative) feature and fuzzy(qualitative) feature. Especially, many difficult problems are often faced that have to evaluate the properties of parts with the crisp and fuzzy feature together. As the basis of determining the similarity of inter-parts, in this method, one aggregate value is calculated on each part. However, because the above aggregate value is only gained from simple additive weighted sum, there is one problem in this method that has been handled the combination effect of inter-parts. For these reasons, in this paper, a proposed method is suggested for representing combination effect in order to cluster parts that have crisp and fuzzy properties into groups using ${\lambda}$-fuzzy measure and fuzzy integral.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.428-433
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• 2000

A disassembility assessment has mostly depend on the subjective decision making from the qualitative element. The work of disassembly is already classified with given disassemble points from the symbolic chart method. It is not useful in the practical assessment because it is not specified. The new method of design for disassembility assessment(DFDA) is practical to introduce the fuzzy number as the conversion of quantitative element from qualitative. It is appled to compare the usefulness of air-cleaner in Korea-Japan passenger-vehicle.