• 지능정보연구
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• 제28권1호
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• pp.69-88
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• 2022

최근 코로나19 팬데믹으로 인해 전 세계 경제와 외교 상황에 급격한 변화가 일어나고 있으며, 수출 의존도가 높은 한국은 이러한 변화에 큰 영향을 받고 있다. 본 연구에서는 기업의 수출전략 수립 및 의사결정 지원을 위해 차년도 수출액 예측 모델을 구축하고, 모델의 예측 결과를 바탕으로 수출 유망국가 추천 방식을 제안한다. 본 연구에서는 모델이 다양한 정보를 학습할 수 있도록 국가별, 품목별, 거시경제 변수 등 선행 연구에서 중요하게 사용된 변수를 다방면으로 수집하였다. 수집한 데이터를 분석한 결과, 국가와 품목에 따라서 수출액의 분포가 매우 비대칭적인 것을 확인할 수 있었다. 따라서, 모델의 예측 성능을 향상시키고 설명력을 확보하기 위해서 분리학습 방식을 사용하였다. 분리학습은 전체 데이터를 동질적인 하위 그룹으로 분리하고 개별 모델을 구축하는 방식으로, 본 연구에서는 수출액을 기준으로 5개 구간으로 데이터를 분리하였다. 모델 학습 과정에서 구간별 특성을 반영하여 구간1부터 구간4까지는 LightGBM을 사용하고, 구간5는 지수이동평균을 사용하였으며 이를 통해 모델의 예측 성능을 향상시킬 수 있었다. 모델의 설명력 확보를 위해서 추가로 구간별 모델의 SHAP-value를 계산하고 중요도가 높은 변수를 제시했다. 또한, 본 연구에서는 예측 모델을 기반으로 2단계 수출 유망국가 추천 방식을 제안했다. 효율적인 수출 전략 수립을 위해서 BCG 매트릭스와 국가별 점수 산출 방식을 사용하였고, 품목별 유망 국가 순위와 수출 관련 주요 정보들을 제공하였다. 본 연구는 다양한 정보를 학습한 머신러닝 모델로 여러 국가와 품목에 대한 예측을 실시하고, 이 과정에서 분리학습 방식으로 예측 성능을 향상시켰다는 점에서 의의가 있다. 또한, 현재 무역 관련 서비스들이 과거 데이터에 기반한 정보를 제공하고 있음을 고려할 때, 본 연구에서 제안한 예측 모델과 유망국가 추천 방식은 기업들의 미래 수출 전략 수립 및 동향 파악에 유용하게 사용될 수 있을 것으로 기대된다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1994년도 춘계공동학술대회논문집; 창원대학교; 08월 09일 Apr. 1994
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• pp.236-243
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• 1994

In this paper we consider the part-machine cell formation decision of the generalized Group Technology(GT) problem in which multiple process routes can be generated for each part. The existing p-median model and similarity coefficient algorithm can solve only small-sized or well-structured cases. We suggest an assignment method for the cell formation problem. This method uses an assignment model which is a simple linear programming. Numerical examples show that our assignment method provides good separable cells formation even for large-sized and ill-structured problems.

• 기술혁신연구
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• 제7권2호
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• pp.21-36
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• 1999

This paper presents a R&D investment model for Information and telecommunications (I&T) technology, which can be used by group decision makers, using multiple objective linear programming (MOLP). The MOLP model involves the simultaneous maximization of three linear objective functions associated with three criteria, which are social, technological, and economic criterion. This model is different from the traditional one which only involves the maximization of economic criterion. The presented problem in this model can be formulated as a problem of optimizing a linear function over an efficient set of MOLP. Its application to the National R&D Project in I&T Industry is also presented. In this application, the Analytic Hierarchy Process (AHP) is proposed to estimate the weights, which are used as the coefficients in each objective function of the MOLP model and in a linear decision function. By solving this problem, it yields a suitable R&D investment ratio to each technology field. It is showed that the MOLP model can be useful decision aid in formulating R&D investment plan in I&T industry which needs to be decided by group decision makers, not by an individual. It is expected that the MOLP model works as the basis for planning R&D investment strategy in I&T industry.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제22권1호
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• pp.65-82
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• 2019

본 연구는 시각적 모델에 따른 학생들의 곱셈식 표현 방법을 지필 검사 및 시선추적 검사를 통해 분석하였다. 지필검사 결과 학생들은 곱셈식으로 제시하는데 있어 묶음 모델에서는 (묶음 내 낱개의 수)${\times}$(묶음의 수), 배열모델에서는 (가로)${\times}$(세로)로 답하는 비율이 높았으나, 배열모델에서는 모양에 따라 (세로)${\times}$(가로)로 답하는 비율이 높은 경우도 있었다. 이러한 결과를 통해 곱셈 지도 시 적절한 모델 제시 방법과 시각적 모델에 대한 곱셈식 표현 방법에 대한 논점을 도출하였다.

• 운동영양학회지
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• 제25권4호
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• pp.17-23
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• 2021

[Purpose] This study aimed to investigate the effect of education based on the health belief model on the physical activity of the staff of the University of Medical Sciences. [Methods] This semi-experimental study was conducted on 130 university staff aged 25-50 years from the Hamadan University of Medical Sciences. Inclusion criteria were having at least 1 year of work experience, lack of acute and chronic physical and mental illnesses, and not using drugs that affect physical activity. The samples were randomly divided into two groups. The experimental group received three training sessions based on the health belief model. Before and 2 months after training, the control and experimental groups were evaluated via the following questionnaires: (1) demographic information questionnaire, (2) Health Belief Model Questionnaire, and (3) International Physical Activity Questionnaire. Finally, data were analyzed statistically. [Results] The training process resulted in a significant increase in the mean scores of the health belief model constructs in the experimental group, but changes in the control group were not significant. Self-efficacy was the strongest predictor of physical activity. [Conclusion] The health belief model is a useful model for improving individuals' understanding of the benefits of physical activity.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2844-2853
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• 2023

A sophisticated Bayesian multilevel model for estimating group bias was developed to improve the utility of the ASTM E900-15 embrittlement trend curve (ETC) to assess the conditions of nuclear power plants (NPPs). For multilevel model development, the Baseline 22 surveillance dataset was basically classified into groups based on the NPP name, product form, and notch orientation. By including the notch direction in the grouping criteria, the developed model could account for TTS differences among NPP groups with different notch orientations, which have not been considered in previous ETCs. The parameters of the multilevel model and biases of the NPP groups were calculated using the Markov Chain Monte Carlo method. As the number of data points within a group increased, the group bias approached the mean residual, resulting in reduced credible intervals of the mean, and vice versa. Even when the number of surveillance test data points was less than three, the multilevel model could estimate appropriate biases without overfitting. The model also allowed for a quantitative estimate of the changes in the bias and prediction interval that occurred as a result of adding more surveillance test data. The biases estimated through the multilevel model significantly improved the performance of E900-15.

• 한국경영과학회지
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• 제28권1호
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• pp.63-77
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• 2003

Group buying is one of the most popular transaction patterns on the internet at least in Korea. Nevertheless, it is hard to find academic researches for it in view of consumer behavior. In this paper, we analyze factors which determine consumer's attitude toward and intention of participation in Internet group buying by comparison of Internet individual one. For this purpose, we propose “lowering price”, “decreasing risk” and “reducing transaction cost” as relative advantages and "lack of product assortment" and "delay of time" as relative disadvantages over individual buying on the Internet. For empirical test, Internet users who have some experiences of individual buying but not group ones on the Internet are surveyed and analyzed. In result, a satisfying model fitness for structural equation model is derived and most hypotheses except the relationship between "decreasing risk" and "attitude toward Internet group buying" are accepted. Our results provide not only academic contribution by suggestion of a research framework but also practical insight by discussion of diverse features in Internet group buying.verse features in Internet group buying.

• 한국지구과학회지
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• 제38권4호
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• pp.303-320
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• 2017

본 연구의 목적은 과학적 모델의 사회적 구성 수업을 적용한 야외지질학습에서 학생들이 만드는 조별 모델 구성 과정에 대해 제약조건을 중심으로 이해하는 것이다. S 영재원 지구과학분과 3조, 12명의 학생들을 대상으로 진행하였다. '관악산은 어떻게 형성되었을까?'를 주제로 야외지질답사 2차시, 과학적 모델의 사회적 구성 수업 3차시로 진행하였다. 조별 모델 구성과정에 관해서는 Nersessian (2008)이 제시한 제약조건을 이론적 근거로 하여 반-구조화된 인터뷰, 야외지질답사, '과학적 모델의 사회적 구성 수업'의 모든 담화, 활동지를 분석하였다. 연구결과는 다음과 같다. 첫 번째 야외지질학습에 적용한 과학적 모델의 사회적 구성 수업에 나타난 제약조건의 출처는 과학 이론, 야외지질답사에서 관찰한 내용, 과학적 모델의 사회적 구성 수업에서 추가로 제공된 것이 있었다. 두 번째 조별 모델링에 영향을 미치는 3가지 종류의 제약조건이 있다. 조별 모델에는 조별 구성원 모두가 동일하게 가지고 있던 것으로 '공통적인 제약조건', 조별 구성원 일부가 가지고 있던 것 중 조별 모델에 반영된 '채택된 제약조건', 마지막으로 초기 모델에는 없었으나 조별 모델 구성과정에서 새롭게 나타난 '생성된 제약조건'이 있었다. 이번 연구는 학교 과학에서 제약조건을 기반으로 조별 모델이 만들어지는 과정을 이해할 수 있을 뿐만 아니라 야외지질학습이라는 수업 사례를 보여줌으로서 실제 적용하는데 이바지 하고자 하였다는 점에서 의의가 있다.

• 대한치과기공학회지
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• 제41권4호
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• pp.263-269
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• 2019

Purpose: The purpose of this study was to evaluate the internal fitness of prostheses fabricated with non-contact extra-oral scanner and those fabricated with intra-oral video scanner, with a comparative accuracy analyses of their precision and trueness. Methods: A polymethyl methacrylate (PMMA) model was fabricated by replicating a master model. The prostheses in the first group were fabricated based on the PMMA model with an intra-oral video scanner (IVS group). Following the fabrication of work models with Type IV Stone that were based on the PMMA model, the prostheses in the second group were fabricated with a non-contact extra-oral scanner (ENB group). The precision and trueness of the prostheses were calculated from comparisons of the three-dimensional images of the internal surfaces of the prostheses and those of the master model. Kruskal-Wallis tests were used to determine the statistical significance, with the level of type 1 error set at 0.05. Results: Trueness (P < 0.009) and precision (P < 0.001) did not differ significantly between the ENB and IVS groups. The IVS group exhibited lower trueness values and larger precision values than the ENB group. Conclusion: Although no significant differences were found in the internal fitness of the prostheses that were fabricated by the two different scanners, the intraoral video scanner-fabricated prostheses had better trueness, whereas the non-contact extra-oral scanner-fabricated prostheses had better precision.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.265-270
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• 2018

PURPOSE. The purpose of this in vitro study was to evaluate the accuracy of a new implant impression technique using bite impression coping and a dual arch tray. MATERIALS AND METHODS. Two implant fixtures were placed on maxillary left second premolar and first molar area in dentoform model. The model with two fixtures was used as the reference. The impression was divided into 2 groups, n=10 each. In group 1, heavy/light body silicone impression was made with pick up impression copings and open tray. In group 2, putty/light body silicone impression was made with bite impression copings and dual arch tray. The reference model and the master casts with implant scan bodies were scanned by a laboratory scanner. Surface tessellation language (STL) datasets from test groups was superimposed with STL dataset of reference model using inspection software. The three-dimensional deviation between the reference model and impression models was calculated and illustrated as a color-map. Data was analyzed by independent samples T-test of variance at ${\alpha}=.05$. RESULTS. The mean 3D implant deviations of pick up impression group (group 1) and dual arch impression group (group 2) were 0.029 mm and 0.034 mm, respectively. The difference in 3D deviations between groups 1 and 2 was not statistically significant (P=.075). CONCLUSION. Within limitations of this study, the accuracy of implant impression using a bite impression coping and dual arch tray is comparable to that of conventional pick-up impression.