• KIPS Transactions on Computer and Communication Systems
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• v.2 no.12
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• pp.533-540
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• 2013

Anonymity is the one of main reasons for substantial improvement of Internet. It encourages various users to express their opinion freely and helps Internet based distributed systems vitalize. But, anonymity can cause unexpected threats because personal information of an online user is hidden. Especially, distributed systems are threatened by Sybil attack, where one malicious user creates and manages multiple fake online identities. To prevent Sybil attack, the traditional solutions include increasing the complexity of identity generation and mapping online identities to real-world identities. But, even though the high complexity of identity generation increases the generation cost of Sybil identities, eventually they are generated and there is no further way to suppress their activity. Also, the mapping between online identities and real identities may cause high possibility of losing anonymity. Recently, some methods using online social network to prevent Sybil attack are researched. In this paper, a new method is proposed for extracting a user's system-wide Sybil-resistant trust value by using the properties embedded in online social network graphs. The proposed method can be categorized into 3 types based on sampling and decision strategies. By using graphs sampled from Facebook, the performance of the 3 types of the proposed method is evaluated. Moreover, the impact of Sybil attack on nodes with different characteristics is evaluated in order to understand the behavior of Sybil attack.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.253-263
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• 2021

Concrete structures are damaged by aging and external environmental factors. This type of damage is to appear in the form of cracks, to proceed in the form of spalling. Such concrete damage can act as the main cause of reducing the original design bearing capacity of the structure, and negatively affect the stability of the structure. If such damage continues, it may lead to a safety accident in the future, thus proper repair and reinforcement are required. To this end, an accurate and objective condition inspection of the structure must be performed, and for this inspection, a sensor technology capable of detecting damage area is required. For this reason, we propose a deep learning-based image processing algorithm that can detect spalling. To develop this, 298 spalling images were obtained, of which 253 images were used for training, and the remaining 45 images were used for testing. In addition, an improved loss function and data augmentation technique were applied to improve the detection performance. As a result, the detection performance of concrete spalling showed a mean intersection over union of 80.19%. In conclusion, we developed an algorithm to detect concrete spalling through a deep learning-based image processing technique, with an improved loss function and data augmentation technique. This technology is expected to be utilized for accurate inspection and diagnosis of structures in the future.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.4
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• pp.44-57
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• 2019

Various studies have been conducted to solve traffic congestions in many metropolitan cities through accurate traffic flow prediction. Most studies are based on the assumption that past traffic patterns repeat in the future. Models based on such an assumption fall short in case irregular traffic patterns abruptly occur. Instead, the approaches such as predicting traffic pattern through big data analytics and artificial intelligence have emerged. Specifically, deep learning algorithms such as RNN have been prevalent for tackling the problems of predicting temporal traffic flow as a time series. However, these algorithms do not perform well in terms of long-term prediction. In this paper, we take into account various external factors that may affect the traffic flows. We model the correlation between the multi-dimensional context information with temporal traffic speed pattern using deep neural networks. Our model trained with the traffic data from TOPIS system by Seoul, Korea can predict traffic speed on a specific date with the accuracy reaching nearly 90%. We expect that the accuracy can be improved further by taking into account additional factors such as accidents and constructions for the prediction.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.261-269
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• 2019

The purpose of this study is to present the effective management strategy of RI based on the results of research on the causal relationship between the regional medical care capacity and the hospital management performance by calculating the RI of the general hospitals in Korea, This research has significance. The results of this study are as follows: First, statistically significant differences were found in Number of beds and recurring profits in urban areas by the general characteristics. Second, the correlations between the RI and the variables of the regional medical use are as follows: Recurring profit ratio, New Outpatient Visits, Operating Margin, Daily Outpatient Visits per 100 Beds, Daily Inpatient Days per 100 Beds, and Average Charge per Inpatient Day. Based on the results of this study, the significance of this study is as follows. First, we calculated the affinity for local medical use, which is the index of local medical utilization. Secondly, it is analyzed according to internal and external environmental factors such as city size, hospital size, etc. It can be said that the hospital provided basic data for establishment of hospital management strategy to increase the utilization rate of local medical care.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.189-196
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• 2020

When concrete member become large like in high rise buildings, hydration heat makes temperature difference inside and outside and cause cracks. The method of using latent heat material as heat reducer could be more accessible, usable and efficient than other methods. Therefore, many studies using PCM as heat reducer are being conducted. Since heat reducer have different reacting temperature, they may be affected by environmental factors like ambient and concrete mixing temperature but studies issuing this are insignificant. Therefore, this paper attempt to evaluate the hydration heat characteristics and quality of concrete using strontium-based PCM under hot weather conditions. As a result, when the strontium-based hydration heat reducer was mixed 3wt.% and 5wt.% in hot weather condition, hydration heat speed and heating rate could be reduced by 8%, 21%, and 75, 85 minutes compared to OPC, respectively. This is considered to be the phase change reaction is relatively promoted when the temperature is high and cause improve performance than room condition result. Later, comparing the efficiency of other types of P.C.M in hot weather condition, and conduct detailed reviews on the strength development in long-term age.

• Journal of the Korea Society of Computer and Information
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• v.27 no.7
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• pp.49-55
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• 2022

In this paper, we propose an obstacle detection method that can operate robustly even in external environmental factors such as weather. In particular, we propose an obstacle detection system that can accurately inform dangerous situations in AR through DB-based feature matching and RANSAC-based multiplane method. Since the approach to detecting obstacles based on images obtained by RGB cameras relies on images, the feature detection according to lighting is inaccurate, and it becomes difficult to detect obstacles because they are affected by lighting, natural light, or weather. In addition, it causes a large error in detecting obstacles on a number of planes generated due to complex terrain. To alleviate this problem, this paper efficiently and accurately detects obstacles regardless of lighting through DB-based feature matching. In addition, a criterion for classifying feature points is newly calculated by normalizing multiple planes to a single plane through RANSAC. As a result, the proposed method can efficiently detect obstacles regardless of lighting, natural light, and weather, and it is expected that it can be used to secure user safety because it can reliably detect surfaces in high and low or other terrains. In the proposed method, most of the experimental results on mobile devices reliably recognized indoor/outdoor obstacles.

• Journal of Korea Entertainment Industry Association
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• v.14 no.1
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• pp.97-106
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• 2020

The mainstream of cinema animated film in today's world is the animated film produced by film companies such as Disney, DreamWorks, and 20th Century Fox. These animated films are influenced by Hollywood blockbusters, high cost, and big-budget, which have brought a gorgeous and splendid audio-visual feast to the global audience. DreamWorks Studios founded in 1994 has become noted in just over ten years. It has produced many high-quality animated works which are well-known all over the world. This achievement is no doubt inseparable from its superior external animation industry environment, and benefited from the American animation industry which commercially operated for almost 100 years. However, in addition to these external environmental factors, DreamWorks' achievements have also come from the extraordinary and superior creation of the animated film scripts, strong narrative script ensures the logic and appeal of animated films. This article takes Kung Fu Panda series, Shrek series, The Prince of Egypt, The Croods, Chicken Run, Megamind and other representative films produced by DreamWorks as key analysis object, using Jean Baudrillard's simulation and imaging theory, Syd Field's screenwriting skills, and Hegel's aesthetic point of view, explores the Creative Style of DreamWorks' Animated Film Script which contains the following four aspects. The script is exaggerated and novel, and the subject matter is rich and targeted. The script creation is very imaginative and can fully express the visual beauty. The structure of the story is well controlled, the space comes from reality but full of imagination. The characters have distinctive personality and the dialogue is moderated but forceful.

• Journal of Navigation and Port Research
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• v.46 no.6
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• pp.538-546
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• 2022

Ports have had a positive impact on urban development in the past, but they also have external diseconomies that reduce the competitiveness of port cities, such as damage to the residential environment. As a result, ports are also important policy targets for local governments. However, opportunities for participation by local governments are limited due to the centralized port policy structure and the lack of port capacity of local governments. Therefore, there is a growing interest in local port governance, which approaches the port as a target of local policy and seeks to solve it based on the participation and cooperation of various members such as local governments, general citizens, local businesses, and NGOs. The purpose of this study was to find the components for establishing local port governance and explore priorities by conducting AHP targeting experts and practitioners. As a result, in order to establish local port governance, it was confirmed that the establishment of an institutional foundation and a socio-cultural atmosphere is the top priority. More specifically, the interest and will of local governors, and local autonomy laws that are the institutional foundation to support the actual operation and the securing of the expertise of local government officials found to be of high priority.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.1
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• pp.71-82
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• 2023

As an alternative to solving social problems, social economic actors are attracting attention as an important alternative. SPC is a private program that pays incentives according to the social performance measured by monetary value. This study measured efficiency by applying DEA to social enterprises that participated in the SPC program and analyzed the factors affecting efficiency through tobit regression. As a result of DEA analysis, it was found that 21% of social enterprises participating in SPC were efficient, but 66% needed to improve their efficiency. In the Tobit regression analysis, the efficiency was relatively low in the case of manufacturing sector, and when the square term of sales is included, the efficiency decreases as sales increase. Through this, it was estimated that external support is needed at a low level sales before crossing the critical point, and that the efficiency of social value creation increases when it grows above a certain level. Moreover, it is significant in that it combines the variables used in the analysis of traditional industrial efficiency while conducting efficiency analysis focusing on the social performance by monetary value, which is considered the most important achievement of social enterprises. It is believed that it will contribute to research related to the environment creation and the requirements of each field in creating social values for social enterprises in the future.

• Journal of Conservation Science
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• v.38 no.3
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• pp.180-191
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• 2022

Wooden cultural heritage are exposed to the external environment as they and there are many difficulties in conservation due to their location and size. Among them, biological damage caused by termites or mold consumes a lot of money and time. Select and use wood preservatives to prevent biological damage: Wood preservatives were selected and the worst environmental conditions, temperature 60±3℃, humidity 55±5%, and light intensity of 0.35 W/m², were subjected to aging treatment to analyze chemical changes. Through the deterioration process, it was confirmed that the change in color difference decreased in the wood preservative treatment compared to the Control group. As a result of measuring the content of the active ingredient contained in the deterioration process of the wood preservative, it was confirmed that the active ingredient content of Gori22 and Bondex Preserve III was higher than that of the comparative Wood Keeper A. Through experiments, the shelf life and treatment period can be predicted by measuring the extent to which wood preservatives affect the change of wood specimens during the deterioration process and the content of active ingredients. In conclusion, various wood preservatives were prepared, and the possibility of selectively selecting wood preservatives according to the environment, topography and period was presented as a major evaluation factor.