• Steel and Composite Structures
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• 제27권4호
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• pp.453-464
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• 2018

The objective of this study is to devise an alternative strengthening method to the ones available in the literature. So, external steel members were used to enhance both flexural and shear capacities of reinforced concrete (RC) beams having insufficient shear capacity. Two types of RC beams, one without stirrups and one with lacking stirrups, were prepared in the study. These beams were strengthened with external steel clamps devised by the authors and with external longitudinal reinforcements. Although the use of clamps alone didn't have a significant effect on the load carrying capacity of the tested beams, the ductility increased approximately tenfold and the failure behavior changed from brittle to ductile. Although the use of clamps and longitudinal reinforcements together did not significantly increase the ductility of the beams, it approximately doubled their load capacities. The results of the experimental study were compared to the ones obtained from nonlinear finite element analysis (NLFEA) and it was observed that they were compatible. Finally, it can be concluded that the devised method could be applied to structural members as an alternative to methods in application due to lightness, low-cost, easy applicable and reliable.

• 응용통계연구
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• 제18권3호
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• pp.521-532
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• 2005

2005학년도 대학수학능력 시험부터는 수험생들마다 응시 과목들이 서로 다르게 구성되어 있으므로, 과목별 난이도의 차이를 보정하기 위하여 표준점수제를 도입하여 운영하고 있다. 그러나 2005학년도 대학수학능력시험에서 본격적으로 표준점수제를 도입하여 운영해 본 결과, 과목선택의 조합에 따라서 과목별 표준점수의 차이가 지나치게 크게 나타나는 등 여러가지 문제점들이 노출되었으며, 이에 따라 표준점수제에 대한 전면적인 개선이 강력하게 요구되기도 하였다. 이 논문에서는 현행 표준점수제의 문제점들을 좀더 심도있게 분석해 보고, 그 개선방안으로 하나의 대안을 제시해 보고자 한다. 이 논문에서 개발한 가산점수제(Additive scoring system)에 의한 결정점수는 현행의 표준점수제가 갖고 있는 여러가지 문제점들을 원천적으로 해소하거나 크게 개선하며, 직관적으로 이해하기 쉬울 뿐만 아니라 계산이 간편하다는 등의 장점들도 갖추고 있다.

• 대한기계학회논문집B
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• 제30권3호
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• pp.208-214
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• 2006

Dimethoxy methane$(CH_3-O-CH_2-O-CH_3)$, also known as methylal or DMM, is an oxygenated additive that contains 42.5% oxygen by weight and is soluble in diesel fuel. It is a colorless liquid and a gas-to-liquid chemical 방tat has been evaluated for use as a diesel fuel component. Experiments were conducted by using the five blends with different volumetric percentage of DMM(2.5, 5, 7.5, 10, and 12.5%) in baseline diesel fuel. The test engine was single cylinder, four stroke, DI diesel engine unmodified. Also, data was collected for steady state operation at 24 engine speed-load conditions. The focus of this study was to investigate the effects of the addition of oxygenated fuel to diesel fuel on the engine-out emissions and the performance. Smoke emissions of all DMM blends were reduced substantially in comparison with conventional diesel fuel. These results indicate that DMM may be an effective blendstock for diesel fuel as an environment-friendly alternative fuel. Besides, this study showed that simultaneous reduction of smoke and NOx emissions could be achieved by oxygenated fuel and EGR method that was applied to decrease NOx emissions increasing with smoke emissions reduction.

• 한국전문물리치료학회지
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• 제19권3호
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• pp.124-131
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• 2012

Most conventional instruments measuring disability rely on total score by simply adding individual item responses, which is dependent on the items chosen to represent the underlying construct (test-dependent) and a test statistic, such as coefficient alpha for the estimate of reliability, varying from sample to sample (sample-dependent). By contrast, item response theory (IRT) method focuses on the psychometric properties of the test items instead of the instrument as a whole. By estimating probability that a respondent will select a particular rating for an item, item difficulty and person ability (or disability) can be placed on same linear continuum. These estimates are invariant regardless of the item used (test-free measurement) and the ability of sample applied (sample-free measurement). These advantages of IRT allow the creation of invariantly calibrated large item banks that precisely discriminate the disability levels of individuals. Computer adaptive testing (CAT) method often requiring a testing algorithm promise a means for administering items in a way that is both efficient and precise. This method permits selectively administering items that are closely matched to the ability level of individuals (measurement precision) and measuring the ability without the loss of precision provided by the full item bank (measurement efficiency). These measurement properties can reasonably be achieved using IRT and CAT method. This article aims to investigate comprehensive overview of the existing disability instrument for back pain and to inform physical therapists of an alternative innovative way overcoming the shortcomings of conventional disability instruments. An understanding of IRT and CAT method will equip physical therapist with skills in interpreting the measurement properties of disability instruments developed using the methods.

• The Journal of Korean Physical Therapy
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• 제32권2호
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• pp.132-136
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• 2020

Purpose: The talk test (TT) is an alternative, self-reported method for prescribing and guiding exercise training in both healthy adults and patients with cardiovascular and pulmonary diseases. This study examined whether the TT is a valid tool for evaluating the exercise intensity during two different types of aerobic activity on a treadmill or stationary bicycle in a healthy population. Methods: A total of ten subjects (six males and four females) who had no medical history related to musculoskeletal, cardiovascular, and pulmonary disorders were enrolled in this study. They were evaluated using the TT, which consisted of three-level of difficulties demanding cardiac loads while performing aerobic activities on a treadmill and bicycle ergometer across two consecutive days in a counterbalanced manner. During the activities, the psychophysiological response markers were collected in terms of the heart rate, oxygen saturation, rating of perceived exertion, and metabolic equivalents. Results: Statistical analyses revealed a significant difference in the between-subject variance regarding the TT level effect (p<0.05). On the other hand, no significant findings were detected on the between-group variance(p>0.05) and the TT level×group interaction (p>0.05). The independent t-test indicated no significant differences in heart rate, oxygen saturation, rating of perceived exertion, and metabolic equivalents at any levels of the TT in the two groups. The TT showed a strong correlation with the rating of perceived exertion. Conclusion: This study showed that the TT is a valid and alternative tool for evaluating the aerobic exercise intensity in a healthy population. In addition, differences in the psychophysiological response markers between two aerobic activities, treadmill and bicycle ergometer, were detected in the same exercise intensity scaled with the TT. The TT can be used to evaluate and prescribe the exercise intensity of aerobic activity in cardiovascular and pulmonary physical therapy.

• 전기학회논문지
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• 제57권3호
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• pp.354-362
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• 2008

This paper presents the new method of power system transient stability simulation, which combines the desirable features of both the time domain technique based on OOP(Object-oriented Programming) and the direct method of transient stability analysis using detailed generator model. OOP is an alternative to overcome the problems associated with the development, maintenance and update of large software by electrical utilities. Several papers have already evaluated this approach for power system applications in areas such as load flow, security assessment and graphical interface. This paper applied the object-oriented approach to the problem of power system dynamics simulation. The modeling method is that each block of dynamic system block diagram is implemented as an object and connected each other. In the transient energy method, the detailed synchronous generator model is so-called two-axis model. For the excitation model, IEEE type1 model is used. The developed mothed was successfully applied to New England Test System.

• 한국경영과학회지
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• 제33권2호
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• pp.1-16
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• 2008

The purpose of this paper is to propose a new binary classification method for predicting corporate failure based on genetic algorithm, and to validate its prediction power through empirical analysis. Establishing virtual companies representing bankrupt companies and non-bankrupt ones respectively, the proposed method measures the similarity between the virtual companies and the subject for prediction, and classifies the subject into either bankrupt or non-bankrupt one. The values of the classification variables of the virtual companies and the weights of the variables are determined by the proper model to maximize the hit ratio of training data set using genetic algorithm. In order to test the validity of the proposed method, we compare its prediction accuracy with ones of other existing methods such as multi-discriminant analysis, logistic regression, decision tree, and artificial neural network, and it is shown that the binary classification method we propose in this paper can serve as a premising alternative to the existing methods for bankruptcy prediction.

• 한국도서관정보학회지
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• 제28권
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• pp.93-135
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• 1998

The purpose of this study was to compare the effectiveness of programmed instruction versus lecture and discussion method on the knowledge of basic reference sources among undergraduate library and information science students. The hypotheses of the study were: 1. Programmed instruction will be more effective than the lecture/discussion method with regard to academic achievement. 2. There will be a significant difference in learning time between the experimental and the control groups. Seventy-eight library and information science students were participated m the study from the two universities in Chungchong Province. A programmed instruction manual, including 4-types of reference sources-dictionary, encyclopaedia, bibliography, indexes and abstracts, 40-item multiple choice post-test, and a questionnaire for the students' attitude toward programmed instruction were developed specifically for this research. The post-test only control-group design was selected for this experimental study. Students were given instruction on the specific reference titles in dictionary, encyclopedia, bibliography, indexes and abstracts. The control group was instructed by the lecture and discussion method while the experimental group completed a programmed instruction manual by themselves. Both the control and the experimental group were tested right after the instruction of 4-types of reference sources. In addition, a questionnaire asking students' attitude toward programmed instruction was administered to the experimental group. The findings from this study are summarized as follows: 1. The results showed that there were no significant difference in the mean of the post test score between the two groups. Therefore, programmed instruction is viable as an alternative method of instruction in the teaching of reference sources. 2. There was a significant difference in the mean of time spending for the leaning of bibliography, indexes and abstracts between the two groups. Accordingly, programmed instruction proved to be more efficient than the conventional lecture/discussion method in terms of learning time. 3. Students showed positive response to programmed instruction and evaluated it very interesting and challenging. In conclusion, the programmed instruction method was just as effective as the lecture/discussion method in the teaching of reference sources. And students' attitude toward the programmed instruction was favorable enough to secure a continued use of this method for the teaching of reference sources.

• 한국전자거래학회지
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• 제22권1호
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• pp.15-35
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• 2017

공공사업 타당성 평가나 대안 선정에서는 대부분 AHP 기법을 활용하여 대안별 가중합 방식으로 최종 점수를 산정하고 그 값이 가장 큰 대안을 선택하고 있다. 특히 타당성 분석과 같은 경우에는 최종 점수가 0.5보다 큰 대안을 선택하게 되는데, 그 값이 0.5보다 얼마나 커야 의사결정이 의미있고 설득력있는 판단이라고 할 수 있는지에 대한 합리적인 기준 없이 적용되고 있다. 한국개발연구원(KDI)에서 제시한 방법론에는 사업진행 대안의 종합 점수가 0.5 근처에 있는 경우를 회색 영역으로 구분하여 신중한 결정을 하도록 제시하고 있는데, 세부기준에 관한 이론적 검토는 빈약하다. 반면, 통계적 검정의 개념을 도입하여 시도된 분석사례에서는 가중합 평가 점수의 확률분포로서 정규분포 또는 베타분포를 가정하였으나, 이에 대한 분포적 타당성은 제시되지 않았다. 본 논문에서는 현재 다양한 분야에서 적용되고 있는 가중합 평가 방식의 사례를 검토하여 그 결과의 통계적 검정의 필요성을 제기하고, 통계적 검정을 위하여 특정 분포를 가정하지 않는 비모수적 검정 방법을 제시한다. 그리고 본 연구에서 제시한 방법을 국방 분야의 사례에 적용하고 그 함의와 함께 향후 연구의 발전방향을 제안한다.

• 한국정보과학회논문지:데이타베이스
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• 제29권4호
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• pp.297-310
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• 2002

실시간 데이타베이스 시스템에서 높은 우선 순위를 갖는 트랜잭션(High Priority Transaction; HPT)의 선행 처리를 보장하기 위해 2PL-HP(Two Phase Locking with High Priority) 방법이 사용된다. 이 방법은 충돌 발생 시 낮은 우선 순위를 갖는 트랜잭션(Low Priority Transaction; LPT)을 철회 또는 대기시킴으로써 충돌을 해결한다. 그러나 HPT가 마감시간을 지키지 못해서 시스템에서 제거되는 경우에는 LPT의 불필요한 철회 및 대기가 발생된다. 최근에 이러한 문제를 해결하고자 대체버전을 이용한 동시성 제어 알고리즘이 제안되었다. 그러나 이 알고리즘은 항상 대체 버전을 생성해야하며, 또한 복잡한 대체 버전을 관리하기 위한 기법이 추가적으로 요구된다. 본 논문에서는 불필요한 자원의 낭비를 막고 LPT의 불필요한 철회 및 대기를 제거할 수 있는 효율적인 동시성제어 알고리즘을 제안한다. 그리고 성능평가를 통해 제안하는 동시성제어 알고리즘이 기존의 대체버전을 이용한 동시성제어 알고리즘에 비해 성능이 우수함을 보인다.