• Industrial Engineering and Management Systems
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• v.7 no.1
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• pp.23-33
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• 2008

This paper proposes an approach to monitoring and scheduling methods for repetitive MIMO-FIFO DESs. We use max-plus algebra for modeling and formulation, known as an effective approach for controller design for this type of system. Because a certain type of linear equations in max-plus algebra can represent the system's behavior, the principal concerns in past researches were how to solve the equations. However, the researches focused mainly on analyses of the relation between inputs and outputs of the system, which implies that the changes or the slacks of internal states were not clarified well. We first examine several properties of the corresponding state variables, which contribute to finding and tracing the float times in each process. Moreover, we provide a rescheduling method that can take into account delays or changes of the internal states. These methods would be useful in schedule control or progress management.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.241-247
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• 2021

This study analyzed the changes in explanatory power of the modified Jones model(1995) for estimating the amount of accruals for Korean Stock Market listed companies from 1990 to 2019. We hypothesized that if the properties of financial variables used in the existing model change over time or change in discretionary ratios, the model's explanatory power will change. As the result of regression models, I found that the explanatory power of the modified Jones model(1995) gradually declined over time. The results may be derived from the increase in accruals itself and the changes in the distribution of variables contained in the model. The results of this research's chronological approach are expected to give important implications to both academic researchers and accounting information users.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.101-106
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• 2022

The main purpose of the study is to determine the key aspects of Agile management as the basis of a management system in the context of globalization. The research methodology includes several scientific and theoretical methods that have achieved this goal. Adaptation of enterprises engaged in the development, production, and sale of innovative products to constant and rapid changes in the external environment requires managers to apply appropriate management methods. The use of Agile management in the management of innovation processes can speed up their implementation, minimize and optimize the use of resources, time, and effort of staff, can increase customer and customer satisfaction with the end result and, consequently, improve the company's competitive position in the market. The results of the study identified key aspects of the application of Agile management in the management system in the context of globalization.

• Health Policy and Management
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• v.10 no.3
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• pp.88-107
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• 2000

The Alcoholics Anonymous(AA) program has been known to be effective in many countries in helping alcoholics to stop drinking and to change their attitudes, beliefs, and behaviors. In this study, we examined AA activities among Korean AA members and measured the self-evaluated physical, social, and mental changes following the entry into the AA program. Out of identified 300 AA members who were attending 18 different AA group meetings at the time of the survey, 207 completed the self-administered questionnaire(response rate of 69.0%). T-test and ANOVA were used to compare the scores of physica(4-items), social(4-items), and menta(10-items) changes according to the level of AA activities. The proportion of the respondents who practiced the 11th step (meditation) or the 12th step (take alcoholics to a meeting after carrying messages) on the regular basis was 66.6% and 37.2%, respectively. The average time spent in meditation per week was $4.8{\pm}5.47$ hours. The length of participation in AA meetings has significantly positive impact on the average score of changes in all the 3 health states; physical(p<.01), social(p<.05), and mental states(p<.01). Also, practicing the 11th step was significantly associated with improvement of social(p<.01) and mental(p<.05), while practicing the 12th step improved only mental states(p<.01). Our findings demonstrated that not only the length of participation in AA meetings but also the practice of regular meditation(11th step) and taking alcoholics to an AA meeting after carrying messages(12th step) are very important for AA members, and lead to great positive changes in physical, social, and mental states following entry into the AA program.

• Journal of Convergence for Information Technology
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• v.8 no.4
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• pp.27-35
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• 2018

This study aimed to analyze the association among dental care consumers' responses to waiting time, hospital image, and patient satisfaction and provide basic data that could help qualitative waiting conditions management related to health care service. A survey was conducted from May 18 to June 20, 2016 in adults who had spent waiting time at dental hospitals or clinics, and the following conclusion was drawn: Hospital image was associated with the changes in reliance on dental care centers in case of long wait, the changes in reuse intentions, and the reservation system, and patient satisfaction was associated with gender, explanation of expected waiting time, the changes in reliance on dental care centers in case of long wait, the changes in reuse intentions, and the reservation system. The positive responses to waiting time was positively correlated with hospital image and patient satisfaction; the negative reaction to waiting time was negatively correlated with hospital image and patient satisfaction; and hospital image was positively correlated with patient satisfaction.

• Journal of KIBIM
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• v.10 no.1
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• pp.1-8
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• 2020

In managing building facilities, spatial information is the basic data for decision making. However, the method of acquiring spatial information is not easy. In many cases, the site and drawings are often different due to changes in facilities and time after construction. In this case, the site data should be scanned to obtain spatial information. The scan data actually contains spatial information, which is a great help in making space related decisions. However, to obtain scan data, an expensive LiDAR (Light Detection and Ranging) device must be purchased, and special software for processing data obtained from the device must be available.Recently, SLAM (Simultaneous localization and mapping), an advanced map generation technology, has been spreading in the field of robotics. Using SLAM, 3D spatial information can be obtained quickly in real time without a separate matching process. This study develops and tests whether SLAM technology can be used to obtain spatial information for facility management. This draws considerations for developing a SLAM device for real-time remote scanning for facility management. However, this study focuses on the system development method that acquires spatial information necessary for facility management through SLAM technology. To this end, we develop a prototype, analyze the pros and cons, and then suggest considerations for developing a SLAM system.

• Journal of Navigation and Port Research
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• v.41 no.2
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• pp.71-78
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• 2017

This paper aims to investigate the time-varying systematic risk of the stocks of Korean logistics firms. For this purpose, the period from January 1991 to October 2016 was examined with respect to 21 logistics companies that are listed on the Korea Exchange. The systematic risk of the logistics stocks is measured in terms of the Capital Asset Pricing Model (CAPM) beta for which the sensitivity of a stock is compared to the return changes of the whole market. Overall, the betas of the stocks of the Korean logistics companies are significantly lower than those of the market unity; however, it was revealed that the logistics betas are not constant, but are actually time-varying according to different economic regimes, which is consistent with the previous empirical findings. This finding is robust across different measurements of the logistics betas. In addition, the impact of macroeconomic factors on the logistics betas was examined. The present study shows that the logistics betas are positively associated with foreign exchange-rate changes.

• Korean Management Science Review
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• v.32 no.3
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• pp.91-103
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• 2015

This study recognizes that there is a correlation between the movement of the financial market and the sentimental changes of the public participating directly or indirectly in the market, and applies the relationship to investment strategies for stock market. The concerns that market participants have about the economy can be transformed to the search terms that internet users query on search engines, and search volume of a specific term over time can be understood as the economic trend of big data. Under the hypothesis that the time when the economic concerns start increasing precedes the decline in the stock market price and vice versa, this study proposes three investment strategies using casuality between price of domestic stock market and search volume from Naver trends, and verifies the hypothesis. The computational results illustrate the potential that combining extensive behavioral data sets offers for a better understanding of collective human behavior in domestic stock market.

• Journal of ILASS-Korea
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• v.21 no.4
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• pp.214-222
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• 2016

Changes in road infrastructure affect driving patterns and pollutant emission characteristics. we analyzed the changes in driving patterns and pollutant emission characteristics of the driving route via measured driving patterns at year 2009 and 2016. Since 2009, there has been an increase in population and traffic demand, including residential areas and industrial facilities. Traffic conditions were improved such as the opening of the highway Inter-Change to Seoul and the construction of underground driveway. As a result, the average vehicle speed increased. More detail comparisons have made on the changes of the underground driveway section and the crossroad section, which are expected to have significant changes in the transportation infrastructure. The vehicle speed distribution of the underground driveway changed from low speed to high speed, and the increase of the time spent at the high speed and high load caused the increase of NOx emissions. The vehicle speed also increased at the crossroad section, and the consequence NOx and $CO_2$ emissions decreased. It is mainly because the decreased time spent at idle, which results from the proper traffic demand management at this area.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.2
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• pp.27-34
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• 2014

In this paper, we investigate the statistical correlation of the time series for temperature measured at the heat box in the automobile drying process. We show, in terms of the sample variance, that a significant non-linear correlation exists in the time series that consist of absolute temperature changes. To investigate further the non-linear correlation, we utilize the volatility, an important concept in the financial market, and induce volatility time series from absolute temperature changes. We analyze the time series of volatilities in terms of the de-trended fluctuation analysis (DFA), a method especially suitable for testing the long-range correlation of non-stationary data, from the correlation perspective. We uncover that the volatility exhibits a long-range correlation regardless of the window size. We also analyze the cross correlation between two (inlet and outlet) volatility time series to characterize any correlation between the two, and disclose the dependence of the correlation strength on the time lag. These results can contribute as important factors to the modeling of forecasting and management of the heat box's temperature.