• International Area Studies Review
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• v.22 no.3
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• pp.175-200
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• 2018

Since the 1990s rising intangible asset has become one of the main driving forces of investment stagnation and jobless growth in advanced income countries. We investigate how does the impact of firms' profitability on employment growth depends on the intangibility and whether the relationship between profitability and tangibility has complementarity. With data on Korean firms over the period 1988~2017 we investigate the effects of intangibility and profitability on employment growth based on the econometric approach of system GMM. The empirical results are as follows. (1) the profit rate has gradually led to lower employment growth, while it had positive effect on employment before the period of financial crisis. The estimated values and signs of profit rate coefficients varies from traditional industries to high/medium tech. industries. (2) the effect of increasing asset intangibility ratio on employment growth is negative and statistically significant. (3) the coefficients of interaction term of (profit rate ${\times}$ intangibility ratio) have significant negative values. It means employment effect of profit rate are becoming higher(lower) as intangibility ratio is at the lower(higher) level; profits rate and intangibility are not complement with each other. The results imply that to boost employment industrial policy which has the capacity to coordinate business intangibility is preferred to expansionary demand policy.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.571-580
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• 2020

In this study, an experimental study on storage media for thermal energy storage system was conducted. For thermal energy storage medium, concrete has excellent thermal and mechanical properties and also has various advantages due to its low cost. In addition, the ultra-high strength concrete reinforced by steel fibers exhibits excellent durability against exposure to high temperatures due to its high toughness and high strength characteristics. Moreover, the high thermal conductivity of steel fibers has an advantageous effect on heat storage and heat dissipation. Therefore, to investigate the temperature distribution characteristics of ultra-high-strength concrete, concrete blocks were fabricated and a heating test was performed by applying high-temperature thermal cycles. The heat transfer pipe was buried in the center of the concrete block for heat transfer by heat fluid flow. In order to explore the temperature distribution characteristics according to different shapes of the heat transfer pipe, a round pipe and a longitudinal fin pipe were used. The temperature distribution at the differnent thermal cycles were analyzed, and the thermal energy and the cumulated thermal energy over time were calculated and analyzed for comparison based on test results.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.87-95
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• 2020

The Incheon airport is a gateway to and from the Republic of Korea and has a great influence on the image of the country. Therefore, it is necessary to predict the number of airport passengers in the long term in order to maintain the quality of service at the airport. In this study, we compared the predictive performance of various time series models to predict the air passenger demand at Incheon Airport. From 2002 to 2019, passenger data include trend and seasonality. We considered the naive method, decomposition method, exponential smoothing method, SARIMA, PROPHET. In order to compare the capacity and number of passengers at Incheon Airport in the future, the short-term, mid-term, and long-term was forecasted by time series models. For the short-term forecast, the exponential smoothing model, which weighted the recent data, was excellent, and the number of annual users in 2020 will be about 73.5 million. For the medium-term forecast, the SARIMA model considering stationarity was excellent, and the annual number of air passengers in 2022 will be around 79.8 million. The PROPHET model was excellent for long-term prediction and the annual number of passengers is expected to be about 99.0 million in 2024.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.625-634
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• 2022

The objective of this study was to examine the relationship between physical activity (PA) level and functional fitness (FF) parameters in community-dwelling older adults aged 65 or above in Korea. Subjects' (M: 1,645; F: 2,394) PA level were assessed using a questionnaire. The subjects were divided into two groups: one below the recommended level of PA(LPA) and one above the recommended level (PA). PA was further classified by intensity level into medium- and high-intensity PA (MIPA and HIPA respectively) groups. FF was assessed based on six test items representing the following fitness areas: lower and upper body strength, agility and dynamic balance, flexibility, aerobic capacity, coordination, and body composition. Of the subjects, 36% met the recommended level of PA. Both MIPA and HIPA were superior to LPA in all FF items(p<.05). The HIPA group was significantly better in terms of agility and dynamic balance, coordination, and lower body strength (only in women) than was the MIPA group(p<.05). In conclusion, PA above the recommended level is needed to maintain functional fitness. In addition, HIPA seems to promote fall-related functional fitness and should be encouraged when safe and feasible.

• Journal of Internet Computing and Services
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• v.23 no.5
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• pp.127-134
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• 2022

Steganography is a hidden technique in which secret messages are hidden in various multimedia files, and it is widely exploited for cyber crime and attacks because it is very difficult for third parties other than senders and receivers to identify the presence of hidden information in communication messages. Botnet typically consists of botmasters, bots, and C&C (Command & Control) servers, and is a botmasters-controlled network with various structures such as centralized, distributed (P2P), and hybrid. Recently, in order to enhance the concealment of botnets, research on Stego Botnet, which uses SNS platforms instead of C&C servers and performs C&C communication by applying steganography techniques, has been actively conducted, but image or video media-oriented stego botnet techniques have been studied. On the other hand, audio files such as various sound sources and recording files are also actively shared on SNS, so research on stego botnet based on audio steganography is needed. Therefore, in this study, we present the results of comparative analysis on hidden capacity by file type and tool through experiments, using a stego botnet that performs C&C hidden communication using audio files as a cover medium in Telegram Messenger.

• Korean small business review
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• v.42 no.2
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• pp.43-67
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• 2020

Studies on technological innovation of SMEs have made remarkable growth both qualitatively and quantitatively, but each study has a limitation to generalize due to lack of data, diversity of methodologies and variables. Therefore, a systematic and comprehensive statistical approach to obtain generalized conclusions through numerous empirical studies can help both the strategic decision making of SMEs and the government's innovation policies. The purpose of this study is to comprehensively analyze the technological innovation process of SMEs through meta-analysis. For this, the antecedents of technological innovation, the relationship between technological innovation and management performance of SMEs were analyzed. The results of using 62,512 samples from 111 domestic empirical studies were as follows; First, to improve the technological innovation of SMEs, internal cooperation, innovation culture, dynamic capabilities, and absorptive capacity were important antecedents. Second, in terms of IP performance, which was introduced as a proxy for technological innovation, human resource management, technological opportunities, commercialization capabilities, financial resources, and R&D expenditure. Third, technological innovation has a medium-sized effect on financial performance, however the effect of IP performance has a small effect size. Lastly, in the relationship between technological innovation and financial performance, the method of measurement and publication type showed statistically significant moderating effects.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.6
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• pp.269-285
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• 2021

As the systematic management of knowledge within an organization is recognized as a core factor for the continuous growth of an organization, organizations are increasing their interest in knowledge management. Knowledge management requires the active sharing of knowledge by insiders of the organization, but there are cases of failure due to the lack of participation of leaders and employees of the organization. The purpose of this study is to suggest a mechanism by which the authentic leadership of leaders in small and medium-sized enterprises(SME), which are relatively lacking in knowledge production capacity, leads to intention to share knowledge of employees. In addition, the study confirms that reciprocal feedback and task interdependence moderate the relationship between antecedent factors and intention to share knowledge. In this study, a research model was derived based on precedent research, and 272 samples were obtained by conducting a questionnaire survey on employees of SME that introduced a knowledge management policy. And, the study verified the hypothesis by applying structural equation modeling based on AMOS 22.0. The results of the study proved that authentic leadership has a positive effect on the intention to share knowledge through organization identification and organization commitment, and confirmed that reciprocal feedback and work interdependence moderate the relationship between knowledge sharing intentions and antecedent factors. This study suggests the mechanism by which the authentic behavior of the leaders of SMEs affects the knowledge sharing behavior of employees, and suggests that work cooperation strengthens the influence of the mechanism.

• Journal of the Korean Geotechnical Society
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• v.38 no.5
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• pp.5-17
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• 2022

A pile is a type of medium for constructing superstructures in weak geotechnical conditions. A pretensioned spun high-strength concrete (PHC) pile is composed of high-strength concrete with a specified strength greater than 80 MPa. Therefore, it has advantages in resistance to axial and bending moments and quality control and management since it is manufactured in a factory. However, the skin friction of a pile, which accounts for a large portion of the pile bearing capacity, is only approximated using empirical equations or standard penetration test (SPT) N-values. Particularly, there are some poor research results on the pile-soil interface under the seismic loads in Korea. Additionally, some studies do not consider geoenvironmental elements, such as groundwater pH values. This study performs sets of cyclic simple shear tests using submerged concrete specimens for 1 month to consider pH values of groundwater and clay specimens composed of kaolinite to generate a pile-soil interface. 0.2 and 0.4 MPa of normal stress conditions are considered in the case of pH values. The disturbed state concept is employed to express the dynamic behavior of the interface, and the disturbed function parameters are newly suggested. Consequently, the largest disturbance increase under basic conditions is observed, and an early approach to the failure under low normal stress conditions is presented. The disturbance function parameters are also suggested to express this disposition quantitatively.

• Journal of Internet of Things and Convergence
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• v.9 no.1
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• pp.71-76
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• 2023

Recently, in order to store and manage big data, research and development of a high-performance storage system capable of stably accessing large data have been actively conducted. In particular, storage systems in data centers and enterprise environments use large amounts of SSD (solid state disk) to manage large amounts of data. In general, SSD uses FTL(flash transfer layer) to hide the characteristics of NAND flash memory, which is a medium, and to efficiently manage data. However, FTL's algorithm has a limitation in using DRAM more to manage the location information of NAND where data is stored as the capacity of SSD increases. Therefore, this paper introduces FTL policies that apply virtual memory to reduce DRAM resources used in FTL. The virtual memory-based FTL policy proposed in this paper manages the map data by using LRU (least recently used) policy to load the mapping information of the recently used data into the DRAM space and store the previously used information in NAND. Finally, through experiments, performance and resource usage consumed during data write processing of virtual memory-based FTL and general FTL are measured and analyzed.

• Journal of the Korea Society of Computer and Information
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• v.14 no.3
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• pp.41-49
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• 2009

Flash memory has become increasingly requestion for the importance and the demand as a storage due to its low power consumption, cheap prices and large capacity medium. This research is to design a high performance flash memory structure for the substitution of a hard-disk by dynamic prefetching of aggressive spatial locality from the spatial smart buffer system. The proposed buffer system in a NAND flash memory consists of three parts, i.e., a fully associative victim buffer for temporal locality, a fully associative spatial buffer for spatial locality, and a dynamic fetching unit. We proposed new dynamic prefetching algorithm for aggressive spatial locality. That is to use the flash memory instead of the hard disk, the proposed flash system can achieve better performance gain by overcoming many drawbacks of the flash memory by the new structure and the new algorithm. According to the simulation results, compared with the smart buffer system, the average miss ratio is reduced about 26% for Mediabench applications. The average memory access times are improved about 35% for Mediabench applications, over 30% for Spec2000 applications.