• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.115-121
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• 2017

This paper is to introduce the main modeling assumptions and data structures associated with right-censored data to describe the successful methodological ideas for analyzing such a field-failure-data when components operating in different environments. The Kaplan - Meier method is the most popular method used for survival analysis. Together with the log-rank test, it may provide us with an opportunity to estimate survival probabilities and to compare survival between groups. An important advantage of the Kaplan - Meier curve is that the method can take into account some types of censored data, particularly right-censoring. The above non-parametric method was used to verify the equality of parts life used in different environments. After that, we performed the life distribution analysis using the parametric method. We simulated data from three distributions: exponential, normal, and Weibull. This allowed us to compare the results of the estimates to the known true values and to quantify the reliability indices. Here we used the Akaike information criterion to find a suitable life time distribution. If the Akaike information criterion is the smallest, the best model of failure data is presented. In this paper, no-nparametrics and parametrics methods are analyzed using R program which is a popular statistical program.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.7
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• pp.113-121
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• 2020

Multi-criteria stock selection is a critical issue for effective investment since the improper stock investment might cause many problems affecting investors negatively. Investors need a range of financial indicators while they are choosing the optimal set of stocks to invest. This study aims to rank the stock of agriculture companies indexed on the Vietnam Stock Exchange Market. The data of 13 agriculture companies during the 2016-2019 periods was analyzed by analytical hierarchy process (AHP) integrated with grey relational analysis (GRA), multi-objective optimization ratio analysis (MOORA), and technique for order performance by similarity to ideal solution (TOPSIS). The AHP method is employed to determine the weights of the proposed financial ratios, and GRA, TOPSIS, and MOORA approaches are used to obtain final ranking. The results indicated that HSL is the top stock with the highest rank and GRA, MOORA, and TOPSIS rankings have strong correlation values between 0.78-1. The findings suggest that the integrated model could be implemented effectively to specific analysis of industries such as oil and gas, textiles, food, and electronics in future research. Further, other techniques like COPRAS, KEMIRA, and EDAS could be employed to evaluate the financial performance of other companies to solve investment problems.

• Journal of the Korean Society of Earth Science Education
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• v.5 no.3
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• pp.276-286
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• 2012

This research is aimed to examine the differences through comparative analysis of the Earth Science contents in the science textbooks between Korea and DPRK. The contents of level and scope in science textbooks between Korea and DPRK are analysed by TIMSS frameworks. The results of this research are as follows : 1. The science textbooks of DPRK is lower in quality of paper, printing to that of Korea, and the illustrations, editing design in the textbooks of DPRK are fewer, monochromic and monotonous while those in Korea. 2. The contents of Earth Science in DPRK's science textbooks rank 37.0%, but those of Korea's science textbooks rank 25.5% of the whole textbooks. The learning units related to Earth Science are generally similar to the level and scope in science textbooks between Korea and DPRK. The type of inquire activities in the textbooks of DPRK largely takes on the model experiment, and it was shown that the number of experiments directly made by children is very small compared to Korea' textbooks. 3. There are lots of differences in Earth Science learning terms and predicates used in the textbooks between Korea and DPRK.

• KIEAE Journal
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• v.16 no.2
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• pp.17-22
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• 2016

Purpose: Sensitivity analysis offers a good guideline for designing energy conscious buildings, which is fitted to a specific building configuration. Sensitivity analysis is, however, still too expensive to be a part of regular design process. The One-at-a-time (OAT) is the most common and simplest sensitivity analysis method. This study aims to propose a reasonable ground that the OAT can be an alternative method for the variance-based method in some early design scenarios, while the variance-based method is known adequate for dealing with nonlinear response and the effect of interactions between input variables, which are most cases in building energy simulations. Method: A test model representing the early design phase is built in the DOE2 energy simulations. Then sensitivity ranks between the OAT and the Variance-based methods are compared at three U.S. sites. Result: Parameters in the upper rank by the OAT do not much differ from those by the Main effect index. Considering design practices that designers would chose the most energy saving design option first, this rank similarity between two methods seems to be acceptable in the early design phase.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.66-71
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• 2018

We propose an online parameter estimation method for surface-mounted permanent-magnet synchronous motor (SPMSM) using an affine projection algorithm (APA). The proposed method estimates parameters with two APAs based on the discrete-time model equation of SPMSM during motor operation. The first APA is designed to estimate inductance, and the second APA is designed to estimate resistance and flux linkage. However, in case when the d-axis current is controlled to 0A, the second APA cannot estimate resistance and flux linkage simultaneously because the matrix rank in APA becomes deficient. To overcome this problem, we temporarily inject a negative reference current input to the d-axis control loop, and the matrix in the APA then becomes full rank, which enables the simultaneous estimation of resistance and flux linkage. The proposed method is verified by PSIM simulation and an actual experiment, and the results reveal that SPMSM parameters can be estimated online during motor operation.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.274-278
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• 2021

Road structures play an important role in collisions involving vehicles and wildlife. Our study aimed to determine the effect of various types of road structures on the risk associated with roadkill. We surveyed 50 previously identified roadkill hotspots, ranked from one to five according to roadkill density. We collected nine types of road structure data on each hotspot road section. Structures with similar characteristics were grouped together, resulting in five categories, namely, median barrier, high edge barrier, low edge barrier, speed, and visibility. We examined the existence of each road structure category at each hotspot rank. The cumulative link model showed that the absence of bottom blocked median barrier increased the roadkill hotspot rank. Our study concluded that a visual obstacle in the middle of roads by the median barrier decreases wildlife road crossing attempts and roadkill risk. We suggest that future roadkill mitigation plans should be established considering these characteristics.

• Asia-Pacific Journal of Business
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• v.11 no.3
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• pp.21-46
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• 2020

Purpose - This study aims to find if the introduction of project finance perspective leads to any modification to the view of PM industry on CSFs of PPP and their relative importance rank. Design/methodology/approach - Through literature reviews, this study came up with a set of CSFs reflective of both perspectives. AHP method was applied for analysis by developing an Analytic Hierarchical Model from this set and survey questionnaires of pairwise comparison to solicit 46 qualified expert responses. Findings - This study concurs with PM industry to acknowledge 'risk allocation', 'legal framework' and 'quality of feasibility' as ones of most important CSFs. However, relative importance rank of individual CSFs goes through significant modification under this study in favor of 'sponsor commitment and quality' but against 'political environment', in particular. Research implications or Originality - Discussions on the CSFs led by PM industry have not been properly reflective of project finance perspective, which is injected into this study to cure the partiality. For researchers, findings of this study may call attention to financing perspective when they discuss CSFs of PPP. Practitioners may benefit from this study by allocating resources in view of this new finding when pursuing PPP projects.

• Educational Technology International
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• v.24 no.2
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• pp.169-202
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• 2023

This study aims to develop instructional design strategies included in educational programs that can effectively improve the educational data literacy of pre-service teachers. We used the design and development model proposed by Richey and Klein and investigated its internal and external validity. Internal validity assessment involved the input of five experts who evaluated the initial instructional strategies. We conducted an educational data literacy education program with 29 pre-service teachers from Korean colleges and graduate schools for external validity. The effectiveness of the program was verified by the Wilcoxon Rank Sum Test, which revealed a meaningful statistical difference between Wilcoxon Rank Sum Test post-scores after the four weeks of online classes. Therefore, this study developed instructional strategies followed by the steps of data-based decision-making: the final instructional strategies encompass 21 strategies, categorized for implementation before, during, and after classes, accompanied by 38 detailed guidelines. This approach bears notable significance as it encapsulates actionable and effective instructional strategies thoughtfully tailored to the unique circumstances and educational setting of the field, as well as the specific characteristics and requirements of the learners.

• Journal of Information Technology Services
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• v.12 no.4
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• pp.255-265
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• 2013

This paper proposes a DEA-AR model for the efficiency evaluation of the iron ore brands in an integrated steel mill. The input factor is defined as unit cost of each brand based on CIF and two output factors are chosen as Fe and Al which are the important ingredients of iron ore. The relative importance between two output factors is determined by several experts using AHP model. The efficiency of each brand is determined using DEA and DEA-AR models. The negative correlation between the DEA-AR efficiency and the unit cost (CIF) is shown as significant whereas no significant correlation exist between the efficiency and the output factors. Also, the Kruskal Wallis rank sum test shows that there exist efficiency differences among the iron ore types whereas no difference is shown among the countries. The result could be utilized in selecting good brands of iron ores based on the DEA-AR efficiency in an integrated steel mill.

• Journal of the Korea Society of Computer and Information
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• v.6 no.1
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• pp.113-118
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• 2001

The purpose of this study is the optimal selection for evaluating alternative computerized manufacturing control software packages. The evaluation and analysis of the alternative computerized manufacturing control software packages is based on a model for Multi-Criteria Decision Making(MCDM). The ultimate of MCDM is to take the best choice among the alternatives or to rank them and the procedure depends on the decision maker's subjective judgement. An example is given to illustrate the application of the MCDM model.