• Journal of KIISE
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• v.43 no.10
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• pp.1104-1114
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• 2016

Software is continuously changing during development and after development. When a change is required, it is difficult to precisely grasp the scope of impact intuitively. A systematic method is needed to accomplish the required change. The purpose of impact analysis on software change is to avoid missing any information by recognizing the ripple effect that the change might cause. This paper proposes a dynamic method that can easily identify the scope of change request by using the association between use-case scenarios and artifacts of UML modeling in object-oriented development environment. By using this approach, the scope of impact that the change might have on other components such as class diagram and sequence diagram in use-case scenarios can be identified by forward tracing. In addition, analysis of influence of possible further changes due to changes in other components can be identified iteratively through backward tracing. The results of this paper are not limited to impact analysis on artifacts and change type. They can also be used as basic guidelines during impact analysis for various change requests.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2595-2618
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• 2018

In this paper, we investigate secure communication with the presence of multiple eavesdroppers (Eves) in a two-tier downlink dense heterogeneous network, wherein there is a macrocell base station (MBS) and multiple femtocell base stations (FBSs). Each base station (BS) has multiple users. And Eves attempt to wiretap a macrocell user (MU). To keep Eves ignorant of the confidential message, we propose a physical-layer security scheme based on cross-layer cooperation to exploit interference in the considered network. Under the constraints on the quality of service (QoS) of other legitimate users and transmit power, the secrecy rate of system can be maximized through jointly optimizing the beamforming vectors of MBS and cooperative FBSs. We explore the problem of maximizing secrecy rate in both non-colluding and colluding Eves scenarios, respectively. Firstly, in non-colluding Eves scenario, we approximate the original non-convex problem into a few semi-definite programs (SDPs) by employing the semi-definite relaxation (SDR) technique and conservative convex approximation under perfect channel state information (CSI) case. Furthermore, we extend the frame to imperfect CSI case and use the Lagrangian dual theory to cope with uncertain constraints on CSI. Secondly, in colluding Eves scenario, we transform the original problem into a two-tier optimization problem equivalently. Among them, the outer layer problem is a single variable optimization problem and can be solved by one-dimensional linear search. While the inner-layer optimization problem is transformed into a convex SDP problem with SDR technique and Charnes-Cooper transformation. In the perfect CSI case of both non-colluding and colluding Eves scenarios, we prove that the relaxation of SDR is tight and analyze the complexity of proposed algorithms. Finally, simulation results validate the effectiveness and robustness of proposed scheme.

• Journal of Information Technology Applications and Management
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• v.17 no.3
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• pp.25-41
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• 2010

F&B(food and beverage) in accommodation industry is a key service that determine the satisfaction of customers in tourism industry. As the importance of the management of quality gets increasingly highlighted in service industry, the innovation in the management of service quality and satisfaction in tourism industry is gaining high attention. In this research, we focused on the improvement and innovation of the management of procurement process for F&B service based on the smart use of information technology. A case and scenario analysis of the improvements in the management of procurement process is performed focusing on a medium-size accommodation business. Future opportunities and potential of further IT-based innovation is discussed.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.253-255
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• 2003

We address an integrated multimedia framework based on a software agent platform for context-aware multimedia computing. We adopt the FIPA (Foundation for Intelligent Physical Agents) platform which provides agent communications and management mechanisms. In order to express context information, we use MPEG-21 metadata for describing user characteristics and usage environment. We encapsulate such context information as a FIPA message to be delivered between agents. Based on context information, appropriate multimedia content delivery becomes possible. We present our system implementation with a use case scenario and show that our proposed framework is effective for context-aware multimedia computing so that personalization of multimedia consumption can be possible.

• International journal of advanced smart convergence
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• v.11 no.3
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• pp.150-156
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• 2022

Recently, the use of Unreal Engine for animation production is increasing. In this situation, Unreal Engine's 'MetaHuman Creator' helps make it easier to apply realistic characters to animation. In this regard, we tried to produce animations using 'MetaHuman' and verify the effectiveness and differences from the animation production process using only Maya software. To increase the efficiency of the production process, the animation process was made with Maya software. We tried to import animation data from Unreal Engine and go through the process of making animations, and try to find out if there are any problems. And we tried to compare animations made with realistic 'MetaHuman' characters and animation works using cartoon-type characters. The use of the same camera lens in realistic character animations and cartoon character animations produced based on the same scenario was judged to be the cause of the lack of realistic animation screen composition. The analysis revealed that a different approach from the existing animation camera lens selection is required for the selection of the camera lens in the production of realistic animation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.164-165
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• 2021

In Korea, in the case of fire scenarios in performance design, it is assumed that the sprinkler is not working. In addition, it does not applicate various fire conditions. Therefore it is not enough that the accuracy about fire scenario. In foreign countries, reseach is being conducted to predict the casualities that can occur due to fire in the building space through statistical risk analysis. Also, research is consistently conducting for design that consider the sprinker probability of operation. Therefore, to analyze the fire risk of each building in Korea, the risk was analyzed using statistical data. As a result, the risk of casualties that can occur for each building use was analyzed as 0.6(persons/cases) for residential buildings, 0.25(persons/cases) for sales facilities, and 0.12(persons/cases) for buisiness facilities.

• Steel and Composite Structures
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• v.20 no.2
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• pp.357-378
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• 2016

The progressive collapse phenomenon in structures has been interested by civil engineers and the building standards organizations. This is particularly true for the tall and special buildings ever since local collapse of the Ronan Point tower in UK in 1968. When initial or secondary defects of main load carrying elements, overloads or unpredicted loads occur in the structure, a local collapse may be arise that could be distributed through entire structure and cause global collapse. One is not able to prevent the reason of failure as well as the prevention of propagation of the collapse. Also, one is not able to predict the start point of collapse. Therefore we should generalize design guides to whole or the part of structure based on the risk analysis and use of load carrying elements removal scenario. There are some new guides and criteria for elements and connections to be designed to resist progressive collapse. In this paper, codes and recommendations by various researchers are presented, classified and compared for steel structures. Two current design methods are described in this paper and some retrofitting methods are summarized. Finally a steel building with special moment resistant frame is analyzed as a case study based on two standards guidelines. This includes consideration of codes recommendations. It is shown that progressive collapse potential of the building depends on the removal scenario selection and type of analysis. Different results are obtained based on two guidelines.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.1
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• pp.162-174
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• 2014

Most shipbuilding scheduling research so far has focused on the load level on the dock plan. This is because the dock is the least extendable resource in shipyards, and its overloading is difficult to resolve. However, once dock scheduling is completed, making a plan that makes the best use of the rest of the resources in the shipyard to minimize any additional cost is also important. Block assignment planning is one of the midterm planning tasks; it assigns a block to the facility (factory/shop or surface plate) that will actually manufacture the block according to the block characteristics and current situation of the facility. It is one of the most heavily loaded midterm planning tasks and is carried out manually by experienced workers. In this study, a method of representing the block assignment rules using a diagram was suggested through analysis of the existing manual process. A block allocation program was developed which automated the block assignment process according to the rules represented by the diagram. The planning scenario was validated through a case study that compared the manual assignment and two automated block assignment results.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.160-160
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• 2022

Floods are the most common natural disasters and are annually causing severe destructions worldwide. Human activities, along with expected increased extreme precipitation patterns as a result of climate change enhance the future potential of floods. There are proven evidence that infrastructure based responses to flood disaster is no longer achieving optimum mitigation and have created a false sense of security. Nature-based solutions(NBS) is a widely accepted sustainable and efficient approach for disaster risk reduction and involves the protection, restoration, or management of natural and semi-natural ecosystems to tackle the climate and natural crisis. Adoption of NBS in decision-making, especially in developing nations is limited due to a lack of sufficient scenario-based studies, research, and technical knowledge. This study explores the knowledge gap and challenges on NBS adoption with case study of developing nation, specially for flood management, by the study of multiple scenario analysis in the context of climate, land-use change, and policies. Identification and quantification of the strength of natural ecosystems for flood resilience and water management can help to prioritize NBS in policymaking leading to sustainable measures for integrated flood management.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.3
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• pp.346-351
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• 2018

The proportion of collision in the total marine accidents is high. The main causes of collisions are navigation rule violation, safety speed violation, neglected watch-keeping and improper collision avoidance action. There are two main ways of avoiding collision situations during maritime navigation: the method of altering course and reducing ship's speed. The purpose of this study is to analyze the result of the collision avoidance action of the reserve officer in case of encountering a multiple number of ships using the ship handling simulator. Full-mission ship handling simulator was used to experiment the situation scenarios that encountered multiple ships. After the experiment, the questionnaire about the experiment was investigated. A total of 50 subjects were participated in the experiment. Experimental results showed that the number of the experimenters who used the engine was 11 and the number of the experimenters who did not use the engine was 39. In the case of using the engine, there were 0 collision accident, 1 grounding accident, and 10 no accidents. However, when the engine was not used, there were 28 collision accidents, 2 grounding accidents, and 9 no accidents. The causes of these results can be found in the survey results. 74 % of the non used engine participants said they were hesitate to use the engine. As can be seen from these results, the reserve officer are hesitant to use the engine and need a way to get correct of it. Maritime course subject can emphasize the importance of using ship's engines and case study also can be it. So, It is considered that various case study scenario will need to developed by various tools in the future.