• Journal of the Korean Society of Radiology
• /
• v.17 no.5
• /
• pp.633-640
• /
• 2023

With the recent development of static and dynamic modulated brachytherapy methods in brachytherapy, which use radiation shielding to modulate the dose distribution to deliver the dose, the amount of parameters and data required for dose calculation in inverse treatment planning and treatment plan optimization algorithms suitable for new directional beam intensity modulated brachytherapy is increasing. Although intensity-modulated brachytherapy enables accurate dose delivery of radiation, the increased amount of parameters and data increases the elapsed time required for dose calculation. In this study, a GPU-based CUDA-accelerated dose calculation algorithm was constructed to reduce the increase in dose calculation elapsed time. The acceleration of the calculation process was achieved by parallelizing the calculation of the system matrix of the volume of interest and the dose calculation. The developed algorithms were all performed in the same computing environment with an Intel (3.7 GHz, 6-core) CPU and a single NVIDIA GTX 1080ti graphics card, and the dose calculation time was evaluated by measuring only the dose calculation time, excluding the additional time required for loading data from disk and preprocessing operations. The results showed that the accelerated algorithm reduced the dose calculation time by about 30 times compared to the CPU-only calculation. The accelerated dose calculation algorithm can be expected to speed up treatment planning when new treatment plans need to be created to account for daily variations in applicator movement, such as in adaptive radiotherapy, or when dose calculation needs to account for changing parameters, such as in dynamically modulated brachytherapy.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.23 no.2
• /
• pp.106-118
• /
• 2024

Interest in personal mobility has increased with the growing significance of first-mile and last-mile connectivity in smart mobility services. This study aims to propose a methodology for setting the service area of free-floating personal mobility sharing services and determining the optimal fleet size for the selected shared service area to address first-mile and last-mile challenges. We utilize population data, smart card data, and building data. Additionally, we estimate latent demand by incorporating age-specific and distance-specific utilization rates based on personal mobility device data. Along with the latent demand, we determine the service area based on locations of transit stops and buildings. We apply the proposed methodology to Yeongjong Island, Incheon. As a result, dense residential areas and popular beachside locations are designated as personal mobility sharing service areas. The fleet size for personal mobility in the dense residential service area is determined to be 1,022 units, while the fleet size for the beachside service area is set at 269 units.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.23 no.2
• /
• pp.1-14
• /
• 2024

The most optimal route-search algorithm thus far has introduced a method of applying node labels and link labels. Node labels consider two nodes simultaneously in the optimal route-search process, while link labels consider two links simultaneously. This study proposes a turn-label-based optimal route-search technique that considers two turns simultaneously in the process. Turn-label-based optimal route search guarantees the optimal solution of dynamic programming based on Bellman's principle as it considers a two-turn search process. Turn-label-based optimal route search can accommodate the advantages of applying link labels because the concept of approaching the limit of link labels is applied equally. Therefore, it is possible to reflect rational cyclic traffic where nodes allow multiple visits without expanding the network, while links do not allow visits. In particular, it reflects the additional cost structure that appears in two consecutive turns, making it possible to express the structure of the travel-cost function more flexibly. A case study was conducted on the metropolitan urban railway network consisting of transportation card terminal readers, aiming to examine the scalability of the research by introducing parameters that reflect psychological resistance in travel with continuous pedestrian transfers into turn label optimal path search. Simulation results showed that it is possible to avoid conservative transfers even if the travel time and distance increase as the psychological resistance value for continuous turns increases, confirming the need to reflect the cost structure of turn labels. Nevertheless, further research is needed to secure diversity in the travel-cost functions of road and public-transportation networks.

• Smart Media Journal
• /
• v.13 no.2
• /
• pp.32-43
• /
• 2024

Game agents which are behavioral agent for game playing are a crucial component of game satisfaction. However it takes a lot of time and effort to create game agents for various game levels, environments, and players. In addition, when the game environment changes such as adding contents or updating characters, new game agents need to be developed and the development difficulty gradually increases. And it is important to have a game agent that can be customized for different levels of players. This is because a game agent that can play games of various levels is more useful and can increase the satisfaction of more players than a high-level game agent. In this paper, we propose a method for learning and controlling the level of play of game agents that can be rapidly developed and fine-tuned for various game environments and changes. At this time, reinforcement learning applies a policy-based distributed reinforcement learning method IMPALA for flexible processing and fast learning of various behavioral structures. Once reinforcement learning is complete, we choose actions by sampling based on Softmax-Temperature method. From this result, we show that the game agent's play level decreases as the Temperature value increases. This shows that it is possible to easily control the play level.

• Information Systems Review
• /
• v.18 no.3
• /
• pp.1-29
• /
• 2016

The radical changes in the business environment have motivated firms to exert serious efforts in managing sustainable development. This study identified the effects of sustainable development on the perceived performance of firms from the viewpoint of the balanced scorecard. Independent variables include economic efforts (of efficiency and ethic of accounting and fairness), environmental efforts (management and energy control), and social efforts (consumer protection and contribution for local community). The result from the analysis of data collected in this research suggests that sustainable development efforts are the critical sources of the incorporated performance of firms. The consumer protection efforts of the local community determine the competitiveness of a firm in managing social responsibility and creating value and social activities. Efforts to reconsider efficiency determine the competitiveness of a firm, becoming the critical factors that determine sustainable performance. Energy control facilitates value creation for the environment through cooperation and harmonization with nature, resulting in sustainable business performances through the vitalization of practical establishments and operations. Sustainable management needs to meet international standards, cooperation, and harmony. These standards are based on the economic, environmental, and social efforts that enable firms to adopt sustainable management efforts that are suitable for their own systems.

• Information Systems Review
• /
• v.20 no.2
• /
• pp.63-85
• /
• 2018

Emerging hotspot and trendy areas are formed into alleys and blocks with the help of viral effects among social network services (SNS) users called "Golmogleo." These users search for every corner of the alleys to share and promote their own favorite places through SNS. An analysis of hot places is limited if it is only based on macroeconomic indicators such as commercial area data published by national organizations, large-scale visiting facilities, and commuter figures. Careful analyses based on consumers' actual activities are needed. This study develops a "social big data analysis methodology" using Instagram data, which is one of the most popular SNSs suitable to identify recent consumer trends. We build a spatial analysis model using Local Moran's I. Results show that our model identifies new trend zones on the basis of posting data in Instagram, which are not included in the commercial information prepared by national organizations. The proposed analysis methodology enables better identification of the latest trend areas formulated by SNS user activities. It also provides practical information for start-ups, small business owners, and alley merchants for marketing purposes. This analytical methodology can be applied to future studies on social big data analysis.

• Information Systems Review
• /
• v.25 no.3
• /
• pp.59-81
• /
• 2023

Elderly suicide problem has become worse in South Korea. With a rapid aging of the population, the trend of suicide among the elderly is expected to accelerate, preventing elderly suicide has been considered an important societal problem. Thus, we aim to investigate various factors that explain suicidal ideation and to develop a predictive model for suicidal ideation in the context of elderly people in South Korea. To this end, this study contributes to addressing the elderly suicide problem. By using seven-year panel data from the Korea Welfare Panel Survey, we extract various potential causal factors for elderly suicidal ideation based on interpersonal theory of suicide and social disorganization theory. Then a panel logit model was employed to assess the impacts of potential factors on suicidal ideation and deep learning and machine learning algorithms were used to develop a predictive model for suicidal ideation of elderly people. The results of our study provide practical implications for preventing elderly suicide by identifying causal factors of suicidal ideation and a high suicidal risk group of the elderly. This study sheds light on synergy of mixed methodology and provides various academic implications.

• Journal of Practical Engineering Education
• /
• v.16 no.4
• /
• pp.553-566
• /
• 2024

The core of this study is to review South Korea's individual-driven training scheme, identify factors hindering elderly participation, and derive implications to support their retention and participation of the elderly in the labor market. This study focuses on population aging, examining the National Lifelong Learning Card system and the current employment insurance scheme, both initiatives of the Ministry of Employment and Labor, to assess the status and issues surrounding elderly participation in vocational training. Based on this analysis, the study seeks to derive policy measures and academic significance to promote elderly participation in vocational training. Based on this analysis, the study aims to derive policy measures and academic significance to promote the participation of older adults in vocational training. The findings emphasized the importance of employment retention for elderly and highlighted the need for vocational training tailored to the specific characteristics of each individual, along with the necessity for professional life-career consulting. Based on these findings, the study proposed recommendations to promote self-directed training among elderly, including enhancing the diversity of vocational training to meet individuals' varied needs, implementing lifelong vocational training programs from a life-cycle perspective, creating age-friendly workplaces at the national level, encouraging individual-driven training participation for the self-realization of elderly, and strengthening the linkage between employment counseling and vocational training for elderly.

• Journal of the Korea society of information convergence
• /
• v.6 no.2
• /
• pp.23-44
• /
• 2013

First, the average scores of personal financial management ability in the college students' financial management attitude were 72.24 for male and 71.65 for female, so that male students showed a little higher score than female. College students who had an experience of opening a bank account and who kept a record of spending revealed higher scores. Those whose parents were elementary or middle school graduates unfolded the highest score, 73.67, and the lowest score, 63.35, from those whose parents had M.A. or Ph.D. The average scores of personal financial management ability in the college students' financial management knowledge indicated almost no difference with 63.26 for male and 63.35 for female. Only whether they had an experience of opening a bank account, keeping a record of spending, or a credit card revealed score differences. Depending on the students' majors, there were also score differences. Students from engineering department came up with the highest score, an average of 66.88, and students from art & physical education department with the lowest score, 53.39, in the financial management knowledge. The personal financial management ability in the college students' financial management function showed that the score of male students was a little higher than that of female, 64.26 versus 63.58. Students who kept a record of spending and whose parents' income was between three million won and four million won marked the highest score, an average of 65.26, and students whose parents' income was below two million won marked the lowest score, an average of 60.43, in the college students' financial management function. There were score differences in the college students' financial management function depending on the students' majors. Students from engineering department came up with the highest score, an average of 69.67, and students from public health department with the lowest score, 63.21.

• Progress in Medical Physics
• /
• v.27 no.1
• /
• pp.31-36
• /
• 2016

The paper discusses radiation dose of dual energy CT on which copper modulation layer, is mounted in order to improve diagnostic performance of the dual energy CT. The radiation dose is estimated using MCNPX and its results are compared with that of the conventional dual energy CT system. CT X-ray spectra of 80 and 120 kVp, which are usually used for thorax, abdominal, head, and neck CT scans, were generated by the SPEC78 code and were used for the source specification 'SDEF' card for MCNPX dose modeling. The copper modulation layer was located 20 cm away from a source covering half of the X-ray window. The radiation dose was measured as changing its thickness from 0.5 to 2.0 mm at intervals of 0.5 mm. Since the MCNPX tally provides only normalized values to a single particle, the dose conversion coefficients of F6 tally for the modulation layer-based dual energy CBCT should be calculated for matching the modeling results into the actual dose. The dose conversion coefficient is $7.2*10^4cGy/output$ that is obtained from dose calibration curve between F6 tally and experimental results in which GAFCHORMIC EBT3 films were exposed by an already known source. Consequently, the dose of the modulation layer-based dual energy cone beam CT is 33~40% less than that of the single energy CT system. On the basis of the results, it is considered that scattered dose produced by the copper modulation layer is very small. It shows that the modulation layer-based dual energy CBCT system can effectively reduce radiation dose, which is the major disadvantage of established dual energy CT.