• Journal of information and communication convergence engineering
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• v.21 no.1
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• pp.82-89
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• 2023

Various machine-learning models may yield high predictive power for massive time series for time series prediction. However, these models are prone to instability in terms of computational cost because of the high dimensionality of the feature space and nonoptimized hyperparameter settings. Considering the potential risk that model training with a high-dimensional feature set can be time-consuming, we evaluate a feature-importance-based feature selection method to derive a tradeoff between predictive power and computational cost for time series prediction. We used two machine learning techniques for performance evaluation to generate prediction models from a retail sales dataset. First, we ranked the features using impurity- and Local Interpretable Model-agnostic Explanations (LIME) -based feature importance measures in the prediction models. Then, the recursive feature elimination method was applied to eliminate unimportant features sequentially. Consequently, we obtained a subset of features that could lead to reduced model training time while preserving acceptable model performance.

• Journal of Korea Trade
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• v.27 no.3
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• pp.179-198
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• 2023

Purpose - There is a paucity of literature dealing with exporters' compliance issues in e-commerce exports. This study aims to fill this gap in the literature by exploring customs initiatives to facilitate the e-commerce exports of small and medium-sized enterprises (SMEs) in the changed compliance environment. The central question of this study was divided into five subquestions: first regarding the pros and cons of trade facilitation measures for Korean e-commerce export clearance; second and third questions about risk and compliance management for facilitation fourth about instruments, the changes in Korean SME compliance burden in e-commerce exports, and ways to improve trade facilitation for e-commerce exports. Design/methodology - This study adopts a qualitative approach using a case study method to understand the SME experience in Korean e-commerce export compliance procedures. A qualitative method was selected to answer research questions requiring an in-depth understanding of the regulatory procedures of customs administration and exporters' compliance burden. Because this study addresses the changing compliance environment for which statistical data is insufficient, a quantitative method is considered inappropriate. Based on the approach, data were collected using multiple sources, including an extensive literature review, interviews, and field observations. Thematic pattern matching was applied to interpret the data. Findings - This study examined ways to support SMEs in the changed e-commerce export compliance environment. Facilitation measures for e-commerce exports have contributed to SME access to global markets, simplifying export clearance procedures, and saving exporters' compliance costs. However, such instruments are limited in promoting SME compliance capabilities to cope with intensified competition and strengthened controls over foreign exporters in cross-border e-commerce. Therefore, this study highlights the importance of reshaping facilitation measures for e-commerce exports based on risk and compliance management theories to a system encouraging exporters' voluntary compliance. Originality/value - This study's academic significance derives from verifying the relationship between trade facilitation instruments and risk and compliance management procedures using an actual case in Korea. It is also of practical importance in navigating the directions for improving facilitation measures for e-commerce exports in a changed compliance environment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.47-55
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• 2016

As one of recent issues in the information and communication industry, internet of things has attracted attention to provide intelligent infrastructure services which connect and share data and information between real and virtual world. According to the development of these internet of things technologies, types of machines, telecommunication devices, and terminals are increasing tremendously. In this situation, connectivity and interoperability between internet of things components are important issues to build a hyper connected society. To visualize this society, it is important to set up and develop information and communication technology (ICT) standards among stakeholders. However, under limited budget and human resources, it is essential to rank standardization work items for setting standards with respect to efficiency. The purpose of this study is to provide a method for setting standardization strategies within group decision making. As a multi-criteria group decision making tool, analytic hierarchy process (AHP) is adopted and applied to determine the priorities of setting work items. The proposed method first defines decision making problem with objective, criteria, and alternatives which produces a hierarchy consisting of upper and lower criteria. Then, pairwise comparisons of academy and public sector experts are performed with respect to their relative meaning and importance. Individual surveys of expert groups are collected and summarized to determine relative criteria importance measures. Furthermore, to deliver reliable importance criteria measures, differences between academy and public sector expert groups are compared and tested using Mann-Whitney non-parametric test. The results are illustrated for useful guidelines to practical group decision making in standardization strategy establishments.

• The Journal of Korean Society for School & Community Health Education
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• v.8 no.1
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• pp.69-77
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• 2007

Background & Objectives: International radiation protection committee recognized the importance of radiation protection from medical practices because the exposure to the radiation in medical practice is higher than any other exposure. The factors on knowledge, attitude and practice of radiation safety of the medical workers engaged in radiation were analyzed in order to improve radiation safety technology. Method: Questionnaires were used for 1200 radiation workers in medical institution from July 23 through September 4 and collected for analysis. Results: Different level of safety measures were practiced by age, marital status, career, and medical facility. The difference was statistically significant. Higher levels of safety measures were practiced in the age group of 50s and married persons. The workers who have more than 20 years experience have higher level of safety measures. The workers of health centers have higher level of safety measures to compare with other workers. The factors which give more concerns on safety practice were self efficacy, practice and knowledge in order. Conclusion: Safety conscious operators should get additional education program to maintain higher level of safety. The operators who do not have much safety concern should be intensive training program for self efficacy and safety.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.151-160
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• 2009

Recently, the importance of rail in the carriage of freight is strongly emphasized. However, the role of rail in the carriage of freight has been decreasing. The purpose of this study is to suggest policy measures for increasing rail freight. Firstly, this study reviews the current situations of the rail freight in Korea and provides theories for the necessity of government support to rail freight transport. Various support measures are identified and evaluated. According to the evaluation, it is shown that the provision of subsidy for facility construction is the most desirable measure in the sense of cost effectiveness and durability of effect. Finally, detailed implementation strategies for the desirable support measures are suggested.

• Journal of Distribution Science
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• v.13 no.2
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• pp.15-24
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• 2015

Purpose - Foreign exchange risk control is in an important component in the international supply chain management. This study shows the importance of the reference period in forecasting future exchange rates with a specific illustration of KIKO currency option contracts, and suggests feasible preventive measures. Research design, data, and methodology - Using monthly Won-Dollar exchange rate data for January 1995~July 2007, I evaluate the statistical characteristics of the exchange rate for two sub-periods; 1) a shorter period after the East Asian financial crisis and 2) a longer period including the financial crisis. The key instrument of analysis is the basic normal distribution theory. Results - The difference in the reference period could lead to an unexpected development in contract implementation and a consequent financial loss. We may avoid foreign exchange loss by using derivatives such as forwards or currency options. Conclusions - We should consider not only level values but also the volatilities of financial variables in making a binding financial contract. Appropriate measures may differ depending on the specific supply chain pattern. We may extend the study with surveys on actual risk measures.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.2
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• pp.322-334
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• 2014

In order to enhance consignment sale businesses of fisheries cooperatives, it is needed to seek measures to accept needs of customers who use the fisheries cooperatives consignment sale market by examining recognition of fishermen. Thus, the purpose of this study is to develop measurement items and scales of the consignment sale factors for fishermen of the fisheries cooperatives port consignment sale market, and to determine the difference between consignment sale factors importance and satisfaction of fishermen. For this, it conducted a survey targeting fishermen who use the fishery product port market consignment sale of the oyster hanging fisheries cooperatives. It used the Importance-Satisfaction Analysis (ISA) for an analysis tool.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.27-32
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• 2009

A technical system generally comprise a number of subsystems and components that are interconnected in such a way that the system is able to perform a set of required function. Because of the complex system structure with serial, parallel and bridged connections, some certain subsystems or components are more critical than the others. The main concern of a reliability engineer is to identify potential failures and to prevent these failures from occurring. In order to prevent fatal failures, proper inspections and maintenance actions for each component are required Considering above objectives of reliability engineers and characteristics of a practical system, several practical method for evaluating system and component reliabilities have developed namely Birnbaum's and Fussell & Vesely's measures. However there are several critical weaknesses in traditional calculation process as the target system gets larger. In this paper, a new technique for calculating component's structural importance is proposed and compared to Birnbaum's with representative system examples (serial, parallel. k out of n, and bridge type).

• Journal of Applied Reliability
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• v.3 no.1
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• pp.1-12
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• 2003

A continuum structure function(CSF) is a non-decreasing mapping from the unit hypercube to the unit interval. A Barlow-Wu type CSF is a CSF whose behaviour is modeled by its underlying binary structure, which is based on the multistate structure functions suggested by Barlow and Wu(1978). As the measures of importance of a system component for a Barlow-Wu type CSF, the structural and reliability importance of a component at system level ${\alpha}$ (0< ${\alpha}$ <1) are defined and their properties are deduced. Computational results are discussed as well for illustrative purpose.

• Journal of the Korean Society of Safety
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• v.37 no.2
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• pp.18-27
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• 2022

Construction accidents are difficult to prevent because several different types of activities occur simultaneously. The current method of accident analysis only indicates the number of occurrences for one or two variables and accidents have not reduced as a result of safety measures that focus solely on individual variables. Even if accident data is analyzed to establish appropriate safety measures, it is difficult to derive significant results due to a large number of data variables, elements, and qualitative records. In this study, in order to simplify the analysis and approach this complex problem logically, data preprocessing techniques, such as latent class cluster analysis (LCCA) and predictor importance were used to discover the most influential variables. Finally, the correlation was analyzed using an alluvial flow diagram consisting of seven variables and fourteen elements based on accident data. The alluvial diagram analysis using reduced variables and elements enabled the identification of accident trends into four categories. The findings of this study demonstrate that complex and diverse construction accident data can yield relevant analysis results, assisting in the prevention of accidents.