• Korean Journal of Remote Sensing
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• v.23 no.4
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• pp.297-309
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• 2007

The first Korean geostationary weather satellite, Communications, Oceanography and Meteorology Satellite (COMS) will be launched in 2008. The ground station for COMS needs to perform geometric correction to improve accuracy of satellite image data and to broadcast geometrically corrected images to users within 30 minutes after image acquisition. For such a requirement, we developed automated and fast geometric correction techniques. For this, we generated control points automatically by matching images against coastline data and by applying a robust estimation called RANSAC. We used GSHHS (Global Self-consistent Hierarchical High-resolution Shoreline) shoreline database to construct 211 landmark chips. We detected clouds within the images and applied matching to cloud-free sub images. When matching visible channels, we selected sub images located in day-time. We tested the algorithm with GOES-9 images. Control points were generated by matching channel 1 and channel 2 images of GOES against the 211 landmark chips. The RANSAC correctly removed outliers from being selected as control points. The accuracy of sensor models established using the automated control points were in the range of $1{\sim}2$ pixels. Geometric correction was performed and the performance was visually inspected by projecting coastline onto the geometrically corrected images. The total processing time for matching, RANSAC and geometric correction was around 4 minutes.

• Korean Journal of Social Welfare Studies
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• no.39
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• pp.167-187
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• 2008

This study explores the trends of social security expenditures after financial crisis in welfare states. For the purpose, this study analyzes changes in social expenditures during 1980~2003 in 22 OECD countries. The results show that average total social security expenditure(as a percentage of GDP) among the 22 countries increased from 18.0% in 1980 to 22.3% in 2003. Compared to sharp increases during the great expansion period of the welfare state before 1980s, the increase in social expenditures after 1980s is substantially weakened. The slowdown in the increases of social expenditures is remarkable in the social democratic welfare states where social expenditures have already reached a high level. On the other hand, social expenditures are considerably increased in the lagged welfare states such as South European countries and Japan. As a result, the cross-national difference in social expenditures has continuously decreased. These findings suggest that financial crisis is a key factor of welfare-state reorganization. Countries where social expenditures are in high level need more reforms under the pressure of financial deficits. Since 1980s, they have tried various reforms especially in pensions and unemployment benefits. Facing new and increasing demands for social security as well as financial limitations, the welfare state needs major reforms in the social security system to increase effectiveness/efficiency of existing programs and to iron out priorities among programs.

• Journal of Broadcast Engineering
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• v.24 no.5
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• pp.879-891
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• 2019

This paper provides performance evaluations of various channel estimation schemes for Advanced Television Systems Committee (ATSC) 3.0 multiple-input multiple-output (MIMO) system under a fixed reception environment. ATSC 3.0 MIMO system can obtain high spectral efficiency and improved reception performance compared to conventional terrestrial broadcasting systems. The ATSC 3.0 MIMO defines Walsh-Hadamard and null pilot encoding algorithms and the amplitude and phase of MIMO pilots are different from those of single-input single-output pilots. At the receiver, linear and discrete Fourier transform (DFT)-based interpolations can be used for the channel estimation. This paper provides the various combinations of the interpolation schemes for channel estimation in time and frequency dimensions, and then analyzes the performance of the various combinations through the computer simulation. The results of computer simulation show that the combination of the linear interpolation in the time dimension and then DFT-based interpolation in the frequency dimension can obtain the best performance among the considered combinations.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.11
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• pp.263-270
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• 2019

Vehicular cloud computing is a new emerging technology that can provide drivers with cloud services to enable various vehicular applications. A vehicular cloud is defined as a set of vehicles that share their own resources. Vehicles should collaborate with each other to construct vehicular clouds through vehicle-to-vehicle communications. Since collaborating vehicles to construct the vehicular cloud have different speeds, directions and locations respectively, the vehicular cloud is constructed in multi-hop communication range. Due to intermittent wireless connectivity and low density of vehicles with the limited resources, the construction of vehicular cloud with multi-hop communications has become challenging in vehicular environments in terms of the service success ratio, the service delay, and the transmitted packet number. Thus, we propose a multi-hop vehicular cloud construction protocol that increases the service success ratio and decreases the service delay and the transmitted packet number. The proposed protocol uses a connection time-based intermediate vehicle selection scheme to reduce the cloud failure probability of multi-hop vehicular cloud. Simulation results conducted in various environments verify that the proposed protocol achieves better performance than the existing protocol.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.496-501
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• 2009

In order to promote the efficiency of strawberry breeding programs, pollen viability of strawberry, 'Seolhyang' was investigated using the fluorochromatic reaction test and seed set under controlled environment. Pistil receptivity was also assessed by hand pollination. Four varieties including 'Maehyang' were used for the test of pistil receptivity with 'Seolhyang' as a pollen parent. Pollen viability remained high for several days under dry conditions as below 33% relative humidity while the greatest loss of viability occurred at 76% relative humidity. The viability was rapidly decreased at high humidity and almost all grains were unviable in 7 days after storage. Pollen viability does not appear to be drastically reduced if the relative humidity is low. Therefore, humidity is more important factor than temperature for the pollen viability in Fragaria${\times}$ananassa. The rate of seed set by hand pollination lasted higher than the average of 77.2% from 2 to 8 days after emasculation when the daily average temperature was around $15^{\circ}C$ in plastic house. It began to decline gradually from 10 days and had decreased dramatically after 12 days except several cultivars. Based on the daily mean accumulated temperature, it is recommended to have an artificial pollination between the range of $45{\sim}140^{\circ}C$ after the emasculation to increase the rate of seed set in strawberry.

• Fire Science and Engineering
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• v.33 no.2
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• pp.155-163
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• 2019

The purpose of this study was to investigate the mediation effect of the job efficacy on the relationship between job stress and career resilience of fire fighting officers. The participants of this study were 151 Jeju Island local fire fighting officers. The research tools used were job stress scale, career resilience scale and job efficacy scale. The data were analyzed using the SPSS statistical program. Pearson's correlation analysis, hierarchical multiple regression analysis and the Sobel test were conducted. The results of this study are as follows: First, there was a significant negative correlation between the job stress and the career resilience and between the job stress and the job efficacy, while there was a significant positive correlation between the job efficacy and the career resilience. Second, the job efficacy of fire fighting officers was found to have a perfect mediation effect on the job stress and the career resilience. As a result, it was found that job efficiency as a mediator to cope with job stress can improve the work efficiency by improving the career resilience of fire fighting officers. Finally, the discussion and implication are provided based on the results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.284-292
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• 2019

The purpose of this study was to analyze the factors influencing the clinical nurse's self-leadership and self-efficacy on job involvement. The survey was conducted from October 20 to December 15, 2017 for 205 nurses working at hospitals located in D city and K province of Korea. Analysis was performed with descriptive statistics, independent t-test, one-way ANOVA analysis, Scheffe's post-hoc test, Pearson correlation analysis, and stepwise multiple regression using the SPSS 21.0 for Windows. The results of the study were as follows. Average score for self-leadership was 3.58, for self-efficacy was 3.56, and for job involvement was 3.36. This study showed positive correlations between self-leadership, self-efficacy and job involvement. Self-leadership, marital status, self-efficacy, and job position were significant influences on job involvement. The explanatory power of influence factors was 43.7%. Based on the results of this study, it is necessary for nursing organizations and hospitals to actively support programs that enhance self-leadership and self-efficacy, which will be used to increase nurses' job involvement and improve productivity and efficiency of nursing work.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.2
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• pp.261-273
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• 2019

Recently, with the development of IT technology, there is an increasing interest in cloud services as the number of users using mobile devices such as mobile phones and tablets is increasing. However, there is a need for techniques to control or control various methods of accessing data as the user's service demands increase. In this paper, we propose a dual key based user authentication model that improves the user 's authentication efficiency by using two keys (secret key and access control key) to access the users accessing various services provided in the cloud environment. In the proposed model, the operation process and the function are divided through the sequence diagram of the algorithms (key generation, user authentication, permission class permission, etc.) for controlling the access right of the user with dual keys. In the proposed model, two keys are used for user authentication and service authorization class to solve various security problems in the cloud service. In particular, the proposed model is one of the most important features in that the algorithm responsible for access control of the user determines the service class of the user according to the authority, thereby shortening the management process so that the cloud administrator can manage the service access permission information of the user.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.169-180
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• 2018

White light-emitting diodes (LEDs) are more economical than fluorescent lights, and provide high brightness, a high lifetime expectancy, and greater durability. As LEDs are closely connected with people's daily lives, dimming control of LED is an important component in providing energy savings and improving quality of life. In visible light communications systems using these LEDs, multiple input multiple output (MIMO) technology has attracted a lot of attention, in that it can attain the channel capacity in proportion to the number of antennas. This paper analyzes the power performance of three kinds of modulation in visible light communications (VLC) systems applied space-time block code (STBC) techniques. The modulation schemes are return-to-zero on-off keying (RZ-OOK), variable pulse position modulation (VPPM), and overlapping pulse position modulation (OPPM), and dimming control was applied. The power requirements and power consumption were used as metrics to compare the power efficiency in $2{\times}2$ STBC-VLC environments under the three kinds of modulation. We confirm that dimming control affects the communications performance of each modulation scheme. VPPM showed greater consumption among the three modulations, and OPPM showed energy savings comparable to VPPM.

• International Area Studies Review
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• v.22 no.4
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• pp.145-166
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• 2018

This study is due to global competition, the wall between regions is disappearing, customer needs are diversified, and market and technology are rapidly changing. Future growth engines, the importance of convergence capabilities for industrial competitiveness is being emphasized more. Therefore, companies should seek innovative means to increase the efficiency of the company by establishing optimized global management environment and establishing direction and strategy for utilization of convergence technology by improving industrial competitiveness. Firms must adopt and utilize related new technologies by strengthening their convergence capabilities through dynamic capabilities that are internal resource bases for new product development and process innovation. Globalize markets and technologies can expect higher innovation performance when aligning strategic direction with formalized technology competencies held by the firm and incorporating the convergence capabilities needed for technological innovation into processes. The study focuses on the effects of market and technology orientation on technological innovation performance, whether dynamic and convergence capabilities affect technological innovation performance, and dynamic and convergence capabilities to mediate between market and technology orientation. For the study, we surveyed 51.4% of global and multinational corporations that are internationally active or headquartered overseas. Based on the previous studies, hypotheses were established and the collected data were analyzed through utilization path analysis and Sobel test.