• Advances in aircraft and spacecraft science
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• v.6 no.5
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• pp.391-407
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• 2019

Flight trajectory optimization has become an important factor not only to reduce the operational costs (e.g.,, fuel and time related costs) of the airliners but also to reduce the environmental impact (e.g.,, emissions, contrails and noise etc.) caused by the airliners. So far, these factors have been dealt with in the context of 2D and 3D trajectory optimization, which are no longer efficient. Presently, the 4D trajectory optimization is required in order to cope with the current air traffic management (ATM). This study deals with a cubic spline approximation method for solving 4D trajectory optimization problem (TOP). The state vector, its time derivative and control vector are parameterized using cubic spline interpolation (CSI). Consequently, the objective function and constraints are expressed as functions of the value of state and control at the temporal nodes, this representation transforms the TOP into nonlinear programming problem (NLP). The proposed method is successfully applied to the generation of a minimum length optimal trajectories along 4D waypoints, where the method generated smooth 4D optimal trajectories with very accurate results.

• Journal of the Korean Society of Safety
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• v.34 no.1
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• pp.14-20
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• 2019

This paper presents a safety assessment based approach for the safe operation for PCS(Power Conditioning System) of photovoltaic and energy storage systems, applying FTA. The approach established top events as power outage and a failure likely to cause the largest damage among the potential risks of PCS. Then the Minimal Cut Set (MCS) and the importance of basic events were analyzed for implementing risk assessment. To cope with the objects, the components and their functions of PCS were categorized. To calculate the MCS frequency based on IEEE J Photovolt 2013, IEEE Std. 493-2007 and RAC (EPRD, NPRD), the failure rate and failure mode were produced regarding the basic events. In order to analyze the top event of failure and power outage, it was assumed that failures occurred in DC breaker, AC breaker, SMPS, DC filter, Inverter, CT, PT, DSP board, HMI, AC reactor, MC and EMI filter and Fault Tree was drawn. It is expected that the MCS and the importance of basic event resulting from this study will help find and remove the causes of failure and power outage in PCS for efficient safety management.

• Journal of Information Technology Applications and Management
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• v.29 no.6
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• pp.81-93
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• 2022

As deep learning technology in natural language and visual processing has rapidly developed, collaborative filtering-based recommendation systems using deep learning technology are being actively introduced in the recommendation field. In this study, OCF-GAN, a hybrid collaborative filtering model using GAN, was proposed to solve the one-class and cold-start problems, and its usefulness was verified through performance evaluation. OCF-GAN based on conditional GAN consists of a generator that generates a pattern similar to the actual user preference pattern and a discriminator that tries to distinguish the actual preference pattern from the generated preference pattern. When the training is completed, user preference vectors are generated based on the actual distribution of preferred items. In addition, the cold-start problem was solved by using a hybrid collaborative filtering recommendation method that additionally utilizes user and item profiles. As a result of the performance evaluation, it was found that the performance of the OCF-GAN with additional information was superior in all indicators of the Top 5 and Top 20 recommendations compared to the existing GAN-based recommender. This phenomenon was more clearly revealed in experiments with cold-start users and items.

• Journal of the Korean Wood Science and Technology
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• v.52 no.3
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• pp.289-299
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• 2024

The current study aimed to investigate the impact of CO₂ enrichment on the width of annual tree rings, earlywood and latewood, and the area of annual growth of Pinus densiflora Siebold & Zucc. grown in open-top chamber (OTC). To this end, two CO₂ enrichment cases were considered, namely 1.4 × increment (560 ppm in OTC-II) and 1.8 × (720 ppm in OTC-III) were compared with the current atmosphere (400 ppm in OTC-I). The CO₂ enrichment conditions for a period of 12 years (2010-2021) were considered, and all measurements were done through image analysis. The study showed that the increment in CO₂ concentrations positively affected the tree growth. The measurement data from the trees in OTC-III were considerably higher than those from OTC-I, whereas those from OTC-II were slightly higher than those from OTC-I. Decreasing patterns of the measured widths and area in 6-7 years after the beginning of CO₂ enrichment was found for all the OTCs. These patterns were possibly due to changes in the physiological features, such as aging. The findings of the present study can have potential uses as fundamental data for forest management considering CO₂ concentrations.

• Journal of the Korean Electrochemical Society
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• v.14 no.4
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• pp.253-260
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• 2011

In this study, computational simulation was performed for thermal management of modules consisting of 10 batteries. Simplified structure and equivalent thermal resistance network was applied to maintain the thermal properties. Verification test of the mesh were in progress to ensure the reliability of 2.6 mm in the narrow gap between the battery, resulting in at least three divided mesh between the shape of the grid was required. Type of air from rear of the module, type of air from top of the module and type of air from bottom of the module were applied and effective cooling methods are discussed based on the location of fan and air intake of the modules. Maximum temperature and temperature differences of modules that directly affect the performance of the module were compared, and also behavior of the fluid was confirmed by comparing the air flow. The best maximum temperature is shown type of air from bottom of the module to $40.27^{\circ}C$ and type of air from top of the module shows smallest temperature difference $0.73^{\circ}C$.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.5
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• pp.1845-1850
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• 2015

Background: Cancer is recently one of the major concerns of the public health both in the world and Iran. To inform priorities for cancer control, this study estimated years of potential life lost (YPLL) and productivity losses due to cancer-related premature mortality in Iran in 2012. Materials and Methods: The number of cancer deaths by sex for all cancers and the ten leading causes of cancer deaths in Iran in 2012 were obtained from the GLOBOCAN database. The life expectancy method and the human capital approach were used to estimate the YPLL and the value of productivity lost due to cancer-related premature mortality. Results: There were 53,350 cancer-related deaths in Iran. We estimated that these cancer deaths resulted in 1,112,680 YPLL in total, 563,332 (50.6%) in males and 549,348 (49.4%) in females. The top 10 ranked cancers accounted for 75% of total death and 70% of total YPLL in the males and 69% for both death and YPLL in the females. The largest contributors for YPLL in the two genders were stomach and breast cancers, respectively. The total cost of lost productivity due to cancer-related premature mortality discounted at 3% rate in Iran, was US$ 1.93 billion. The most costly cancer for the males was stomach, while for the females it was breast cancer. The percentage of the total costs that were attributable to the top 10 cancers was 67% in the males and 71% in the females. Conclusions: The YPLL and productivity losses due to cancer-related premature mortality are substantial in Iran. Setting resource allocation priorities to cancers that occur in younger working-age individuals (such as brain and central nervous system) and/or cancers with high incidence and mortality rates (such as stomach and breast) could potentially decrease the productivity losses and the YPLL to a great extent in Iran.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.321-336
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• 2005

The objective of this paper is to verify, based on the Jaworski & Kohli's previous study (1993) , relationships among top management factor, interdepartmental cooperation, intra-organizational Properties , marketing capability, environmental factor, and export Performance as factors for enhancement of export marketing as pursued by Korean media production enterprises which target overseas market centered on the 'Feel Korea' trend which is recently gaining popularity in Asian economies. This study based its theoretical framework on previous studies on market orientation. For day analysis, this study surveyed a total of 306 employees in 36 media & contents enterprises including KBS, MBC, SBS. etc. Of them, 106 subjects who were primarily engaged in marketing were utilized for final analysis. Based on the previous studies for each variables, a theoretical study model was developed. As a result, the study result was found to be consistent with the previous ones on market orientation by Jaworski & Kohli (1993).

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.6
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• pp.117-128
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• 2014

This is the case study of SATREC INITIATIVE company which is the unique domestic production of commercial satellites. We examined the path and pattern for accumulation of technological capability and technology learning process. This case study show that the process of technological innovation and their influencing factors. First, the technological learning of the satellite industry follows the stage of technological acquisition, absorption, improvement and is embodied by the technological capability. Second, accumulated technological capability of the satellite industry influences the technology innovation. Third, the top management team(TMT) affects the technological learning and technological capability. Fourth, TMT has a moderating role between the technological capability and the performance of technological innovation. Finally, technological innovations in the small and venture business would be the source of technological capability and technological learning. The implications of this study are as follows. TMT has the very important role for the technological innovation and affect the technology development and the production. Also technology-based companies must gain a competitiveness advantage through technological learning and technological innovations for sustainable growth.

• The Journal of the Korea Contents Association
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• v.18 no.2
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• pp.11-25
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• 2018

This study analyzed how the entrepreneurial orientation of Korean CEO influenced to the performance of companies in entertainment business. The research verified the direct influence that the entrepreneurial orientation of entertainment business affected the companies' performance, and examined the diversity of TMT and the control effect of corporate governance. This study contributed to previous researches in two ways. The first, the study verified the concept of entrepreneurial orientation on entertainment business which was only focused on manufacturing or IT industry although the entrepreneurial orientation received attention as a significant research issue on middle and small venture businesses. Second, the research also verified the characteristics of CEO and executives bringing the concept of TMT's diversity in entertainment companies which were dependent on person's capacity. As a result of the research, the entrepreneurial orientation (innovation, proactiveness, risk-taking) of entertainment entrepreneurs led to a positive effect on financial performance. The research showed that the more TMT was diverse or ownership oriented management, the more broadened the positive effects.

• The Journal of the Korea Contents Association
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• v.16 no.6
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• pp.576-588
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• 2016

The main objective of this study is to investigate the overseas performance of CGV in order to boost Korean wave and movie platform competitiveness. The focus of this study is to on how CGV may enhance the market share of china market, emphasizing the entrepreneurial orientation of top management team and differentiated entrant strategy based on Korean wave. This study suggests key factors in the china movie platform market expansion process of CGV. In order to analyze this mechanism, we employ a case study method design. The case study results show that there are differences of CGV strategy in movie platform characteristics and the important key factors of growth depending on market situation. The most important thing is that entrepreneurial orientation of top management including differentiated entrant strategy and Korean wave-oriented vision enhance between brand loyalty and market share in china market. In addition, growing overseas impacts of CGV support on Korean wave entertainment and globalization of movie platform industry. Contributions and implications for the academic and managerial field are discussed.