• Journal of Korea Technology Innovation Society
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• v.12 no.1
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• pp.113-136
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• 2009

The purpose of this study is to develop meta evaluating indicators for Defense R&D Programs in Korea. At first, the four components of this meta evaluation model were designed, which are evaluation context, evaluation input, evaluation process, evaluation output. And fifty two indicators were developed for this meta evaluation. Basic model of meta evaluation was derived from the literature review and brain storming. And this meta evaluation model was determined by adapting the result of experts who performed evaluations for Defense R&D Programs in recent years. Factor Analysis method was used to verify the validity of meta evaluation model. The survey of fifty three members turned out that Cronbach' ${\alpha}$ was over 0.6 in evaluation components and items. And the reliability of evaluation context was 0.877, that of evaluation input was 0.755, that of evaluation process was 0.755, that of evaluation output was 0.755 respectively. Analytic Hierarchy Process (AHP) method was used in assigning the evaluation weight. The survey of twenty two members showed that the Consistency Ratio was 0.09 in evaluation components and items.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.304-309
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• 2004

Recently, the needs for multimedia stream such as digital audio and video in the Internet has increased tremendously. Unlike TCP, the UDP protocol, which has been used to transmit streaming traffic thorough the Internet, does not apply any congestion control mechanism to regulate the data flow thorough the shared network And it leads to congestion collapse of the Internet and results in long-term transmission delay. To avoid any adverse effect on the current Internet functionality, a now protocol of modification or addition of some functionality to perform congestion control and to reduce huge transmission delay in transmitting of multimedia stream are in study. TCP-friendly congestion control mechanism is classified into two : one is window-based congestion control scheme using general window management functionalities, the other is rate-based congestion control scheme using TCP modeling equation. In this paper, we propose an algorithm for improving the transmitting rate on a hybrid TCP-friendly congestion control scheme combined with widow-based and late-based congestion control for multimedia stream. And we also simulate the performance of improved TEAR implementation using NS. With He simulation results, we show that the improved TEAR can provide better fairness and lower rate fluctuations than TCP.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.312-312
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• 2018

우리나라의 기후 지형적 특성에 따라 연강수량의 50% 이상이 여름철에 내리며 이러한 짧은 기간에 집중적으로 내리는 강수패턴 조건하에서 수공구조물 설계시 대부분 극치빈도분석을 활용한다. 우리나라의 경우 단일 Gumbel 분포를 활용한 극치빈도분석을 많이 이용한다. 하지만, 최근 이상기후로 인하여 전세계적으로 강수패턴의 특징이 급격히 변하고 있으며, 우리나라의 강수패턴 또한 바뀌어가고 있다. 연강수량의 대부분은 태풍과 장마로 인한 강수량으로 이루어져 있고, 일반적으로 두 개의 모집단으로 이루어진 형태를 보인다. 앞선 연구에서 두 개 이상의 첨두를 가지는 형태의 연최대강수량 자료에 대해 8개의 지속시간별(1, 2, 3, 6, 9, 12, 18, 24hr)로 Bayesian 기법의 단일 Gumbel 분포형과 혼합 Gumbel분포형 기반의 극치빈도분석 결과를 비교하였고, 혼합 Gumbel 분포형이 이중첨두 부분의 거동을 효과적으로 모의하는 것을 확인하였다. 본 연구에서는 이상기후로 인한 강수량의 특징의 급격한 변화에 일정한 패턴이 있음을 가정하고 이중첨두의 연 최대일강수량 자료에 대해 혼합 Gumbel 분포형 기반 비정상성 빈도분석을 실시하였다. 정상성 빈도분석과의 비교를 위해 확률분포의 매개변수 산정시 우도함수를 Bayesian 기법을 통해 산정하여 각 분포형의 Bayesian information criterion(BIC) 값을 비교하였다. 비정상성일 경우의 BIC 값이 정상성일 경우 보다 작게 산정되었고, 강수패턴이 경향성을 가지는 것으로 판단할 수 있었다. 비정상성 혼합 Gumbel 분포형 모델은 최근 급격한 강수패턴의 변화에 대한 대응책으로서 활용성이 높을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.382-382
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• 2018

최근 기후변화 및 도시화로 인해 집중호우와 도시 내의 불투수층이 증가하고 있으며, 현재 도심의 강우관리시스템이 한계에 달하여 수재해 피해가 급증하고 있다. 이와 같은 문제를 해결하기 위한 방안으로 저영향개발 기법이 대두되고 있으며, 본 기법은 해당 지역의 강우를 분산식 빗물처리 하여 도시 내의 수문학적 특성을 개발이전 상태로 회복 및 유지하는 기술이다. 저영향개발 기법의 종류는 투수성 포장, 옥상녹화, 빗물정원, 식생저류지, 식생화분 등이 있다. 본 연구에서는 저영향개발 기법 중 하나인 투수성 아스팔트에 대한 우수저감 효과를 분석하기 위해 경상남도 양산시 부산대학교 양산캠퍼스 그린인프라 저영향개발 센터에서 주차장형 LID 시설의 투수성 아스팔트 포장과 대조군인 불투수 콘크리트 포장을 실험대상으로 선정하였다. 포장체는 $10.85m(L){\times}2.3m(B){\times}0.9 m(H)$의 크기로 원지반 침투가 없는 박스형 실험시설로써 이동형 강우모의장치를 이용하여 인공강우실험을 실시하였다. 강우모의 시에 발생하는 지표유출 및 침투유출은 각 유공관을 통해 모니터링 박스에 차집되어 실시간으로 웹사이트 상에 저장된다. 저장된 자료를 이용하여 투수성아스팔트의 첨두유출량 저감, 지체시간지연효과를 분석하였다. 분석된 결과를 통해 첨두유출량은 11%저감되었고 투수성 아스팔트와 불투수 콘크리트는 각각 3시간, 1시간 동안 유출되어 2시간의 차이를 보여준다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.135-140
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• 2021

In this paper, we propose an on-line mechanism that simultaneously detects cracks and profiling pavement blocks to detect the displacement of ground surface adjacent to the excavation in the urban area. The proposed method utilizes a 2D laser to profile the information about pavement blocks including the depth and distance among them. In particular, it is designed to enable the detection of cracks and portholes at runtime. For the experiment, real data was collected through Gocator, and trainng was carried out using Faster R-CNN. The performance evaluation shows that our detection precision and recall are more than 90% and the pavement blocks are profiled at the same time. Our proposed mechanism can be used for monitoring management to quantitatively detect the level of excavation risk before a large-scale ground collapse occurs.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1047-1054
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• 2022

With the advent of SDN, a next-generation network technology that separates the hardware and software areas of network equipment and defines the network using open source-based software, it solves the problems of complexity and scalability of the existing network system. It is now possible to configure a custom network according to the requirements. However, it has a structural disadvantage that a load on the network may occur due to a lot of control communication occurring between the controller and the switch, and many studies on network load distribution to effectively solve this have been preceded. In particular, in previous studies of load balancing techniques related to flow tables, many studies were conducted without consideration of flow entries, and as the number of flows increased, the packet processing speed decreased and the load was increased. To this end, we propose a new network load balancing technique that monitors flows in real time and applies dynamic flow management techniques to control the number of flows to an appropriate level while maintaining high packet processing speed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.241-251
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• 2006

This study analyzed the topographical characteristics by extracting property factors of stream (stream order, number of stream, stream length, mean stream length) and property factors of basin (basin area, basin length, total stream length, total number of stream, basin mean width, form factor, maximum stream order, basin density, stream frequency, relief ratio, mean elevation, mean, slope, maximum elevation) from DEM (digital elevation model) and stream network generated by 1:5,000 NGIS (national geographical information system) data for the Bukhan-river basin. In addition, topographical factors for upper, mid stream and lower stream were analyzed and the mutuality of the factors by linear and nonlinear regression curve was identified.

• Journal of the Korea Society of Computer and Information
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• v.29 no.6
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• pp.113-120
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• 2024

With the advancement of information and communication technology, we can easily generate various forms of data in our daily lives. To efficiently manage such a large amount of data, systematic classification into categories is essential. For effective search and navigation, data is organized into a tree-like hierarchical structure known as a category tree, which is commonly seen in news websites and Wikipedia. As a result, various techniques have been proposed to classify large volumes of documents into the terminal nodes of category trees. However, document classification methods using category trees face a problem: as the height of the tree increases, the number of terminal nodes multiplies exponentially, which increases the probability of misclassification and ultimately leads to a reduction in classification accuracy. Therefore, in this paper, we propose a new node expansion-based classification algorithm that satisfies the classification accuracy required by the application, while enabling detailed categorization. The proposed method uses a greedy approach to prioritize the expansion of nodes with high classification accuracy, thereby maximizing the overall classification accuracy of the category tree. Experimental results on real data show that the proposed technique provides improved performance over naive methods.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.1
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• pp.86-95
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• 2014

Productivity improvement of a shipbuilding company depends on how efficiently its limited resources are managed and utilized. Recently, research on modeling and simulation (M&S) to support shipyard production management system has been being under study. The production management based on M&S rejects decision making on experience, and it can establish productivity improvement method based on quantitative and specific data. In this paper, M&S is applied to the long-term plan as a part of the production planning in shipyards. To this end, the long-term plan processes and related management systems are analyzed. Based on the analysis, a simulation model and an application system using commercial simulation software are suggested. And basic structure of the suggested system is based on web technology such as Rich Internet Application, web services protocol for compatibility with existing shipyard enterprise systems. Utilizing the results of this study, it is expected that shipyard production planners can settle down work flow, in which one can establishes the production plan, simulates the plan, and analyzes the results, enabling a more reliable production plans.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.4
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• pp.163-168
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• 2022

As cloud computing and the Internet of things are getting popular, the number of devices in the Internet of things computing environments is increasing. In addition, there exist various Internet-based applications, such as home automation and healthcare. In turn, existing studies explored the quality of service, such as downtime and reliability of tasks for Internet of things applications. To enhance the quality of service of Internet of things applications, cloud-fog computing (combining cloud computing and edge computing) can be used for offloading burdens from the central cloud server to edge servers. However, when devices inherit the mobility property, continuity and the quality of service of Internet of things applications can be reduced. In this paper, we propose a resource management scheme based on live migrations for mobility support in edge-based fog computing environments. The proposed resource management algorithm is based on the mobility direction and pace to predict the expected position, and migrates tasks to the target edge server. The performance results show that our proposed resource management algorithm improves the reliability of tasks and reduces downtime of services.