• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.3
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• pp.291-301
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• 2012

A scalar metric for the assessment of hull surface producibility was known to be useful in estimating the complexity of a hull form of ships or large offshore structures by looking at their shape. However, it could not serve as a comprehensive measuring tool due to its lack of important components of the hull form such as longitudinals, stiffeners, and web frames attached to the hull surface. To have a complete metric for cost estimation, these structural members must be included. In this paper, major inner structural members are considered by measuring the complexity of their geometric shape. The final scalar metric thus consists of the classes containing inner members with various curvature magnitudes as well as the classes containing curved plates with single and double curvature distribution. Those two distinct metrics are merged into a complete scalar metric that accounts for the total cost estimation of complex structural bodies.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.1
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• pp.33-46
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• 2013

A computational fluid dynamics (CFD) code, dubbed SNUFOAM, was developed to predict the performance of ship resistance using a CFD tool kit with open source libraries. SNUFOAM is based on a pressure-based cell-centered finite volume method and includes a turbulence model with wall functions. The mesh sensitivity, such as the skewness and aspect ratio, was evaluated for the convergence. Two wall functions were tested to solve the turbulent flow around a ship, and the one without the assumption of the equilibrium state between turbulent production and dissipation in the log law layer was selected. The turbulent flow around a ship simulated using SNUFOAM was compared to that by a commercial CFD code, FLUENT. SNUFOAM showed the nearly same results as FLUENT and proved to be an alternative to commercial CFD codes for the prediction of ship resistance performance.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.69-78
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• 2008

Batch signature is a cryptographic tool which efficiently generates several signatures for multiple messages. Previously proposed batch signature schemes do not allow a signer to generate a signature immediately for sequentially asked signing queries. In other words, the previous schemes are not applicable when signing requests are not simultaneously given to the signer. In this paper, we propose flexible batch signatures which can provide batch signing for sequential signing requests. Moreover, our schemes are well suited for imbalanced environment where two communicating parties have different computing powers.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.6
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• pp.450-460
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• 2013

A complex system such as defense systems is in a form of System of Systems (SoS) in which each component is a system being independent of other component systems. Dynamical behavior of SoS is represented by a composition of behaviors of component systems. Thus, a M&S tool/environment would not be efficient for development of heterogeneous models nor for simulation in a centralized environment. Moreover, such an environment restricts reusability and composability. This paper presents an interoperation method for M&S of defense systems as SoS. The approach first develops component system models using tools, each specialized to M&S of each component system. It then interoperates such simulations together to simulate a whole system as SoS. HLA/RTI is employed for such interoperation, which is a DoD/IEEE standard to support interoperation. We will introduce a case study for interoperable simulation of defense systems, which consists of a wargame simulator and a communication simulator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.19-25
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• 2014

In the LED lighting applications, because LED packages are the origin of heat generation, there are thermal design problem on heat sinks. In the thermal design, it is important to consider the total volume and the total weight of heat sink simultaneously. In this study, an Al 6063 heat sink was optimized using Computational Fluid Dynamics(CFD) simulation tool for the cooling of 30W LED module, and then the cooling performance and the total weight of heat sinks with Al 6063 and Thermal Conductive Polycarbonate(TCP) were compared under the same conditions. As the result of simulation, an Al 6063 heat sink was optimized with 22 ea. of fins and 1.6 mm of fin thickness. LED Junction Temperature of the TCP Heat Sink was $5.6^{\circ}C$ higher, but total weight of it was 47 % less than the Al 6063.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1251-1258
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• 2016

Recently, leaks of the personal information of Internet users have been occurring too frequently. Generally, Internet users have email accounts. The use of email as a communications tool in the private and public sectors has increased. Therefore, in email usage, password management to ensure a more secure email service is most important. In this study, we conducted an online survey of email users and analyzed their responses by using structural equation modeling software to find the psychological and behavioral characteristics of their password management. The results of this study provide useful suggestions on information security strategies related to email password management at both the enterprise and individual levels.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.694-696
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• 2017

Image processing is being hailed as an important field with various applications as the digital information era advances. In particular, studies on methods to remove noise from images are being actively undertaken. This paper suggests an image restoration filter that processes through a weighted filter in accordance with the direction of partial masks to preserve edge while replacing the noise in the images with neighboring pixels. The PSNR(peak signal to noise ratio) was used as a tool to objectively judge the improvement effects compared to existing methods.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.662-664
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• 2014

소프트웨어 자산을 효과적으로 유지보수하기 위하여 자산의 어느 부분을 수정할 때 변경에 의해 영향을 받는 부분을 예측하여 필요한 경우 함께 수정하도록 하는 방법이 필요하다. 이러한 변경 영향 분석 방법을 사용하면 개발자는 소프트웨어 자산을 수정할 때 함께 수정해야 할 부분을 수동으로 찾는 노력을 줄일 수 있고, 함께 수정이 필요한 부분을 빠뜨리지 않을 수 있어서 자산 변경 시 발생할 수 있는 오류를 방지할 수 있다. 변경 영향 분석 방법을 기업의 소프트웨어 개발에 실제적으로 적용하기 위해서는 방법을 지원하는 도구가 필수적이다. 하지만 기존 상용도구들을 현업에서 사용할 때 한계가 있어 개발자의 요구사항을 반영한 새로운 변경 영향 분석 도구의 개발이 필요하였다. 본 논문에서는 이러한 도구의 요구사항을 설명하고, 이를 반영하여 개발한 새로운 지원도구를 제안한다. 제안하는 도구는 플래시 메모리 소프트웨어 도메인에 적용되어 검증되었다.

• The Journal of Korean Society for School & Community Health Education
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• v.17 no.2
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• pp.45-55
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• 2016

Objectives: This study examined the factors the oral health promotion in university students. It is to identify factors that affect activities for life style and subjective oral health status. Methods: The subjects are 385 students who agreed to participate in research Cheonan. Questionnaires were distributed and collected after they filled in by themselves. SPSS ver.20.0 was used for analysis to get the reliability of each analysis tool. The genral characteristics was analysis of frequency. For comparison oral health promotion and subjective oral health status related to the genral characteristics, it was used t-test, ANOVA. Pearson's correlation was used correlation of each variable. multiple linear regression analysis was used to comprehend that affects oral health promotion behavior. Results: There was statistical significant difference in factors affecting subjective oral health status, departments of health. dietary lifestyle was low correlated among sub factors of lifestyle. oral health promotion behavior wasn't related to subjective oral health status. dietary lifestyle had the most significant impact to oral health promotion behavior. Conclusion: To progess through oral health education program of the university students, it is asked to configure the content that can handle regular lifestyle, rather than focusing on smoking habits and drinking habits.

• Safety and Health at Work
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• v.8 no.4
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• pp.410-412
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• 2017

Post-traumatic stress disorder (PTSD) is a serious problem not only among workers who experience industrial accidents but also among workers who witness such accidents. Early intervention is needed to prevent prolonged psychological problems. There has been no study conducted regarding the psychological problems of and interventions for bystander workers in Korea. This study introduces the experience of intervention on psychological problems at the Busan Workers' Health Center workers who witnessed their colleagues' death. An investigation and an intervention were conducted according to the Korean Occupational Safety and Health Agency (KOSHA) Guide. In total, 21 individuals including indirect observers showed statistical differences on scores of the Impact Event Scale Revised and the Patient Health Questionnaire 9 after the intervention. Future interventions and research involving a larger sample size over a longer period are needed. The KOSHA Guide could be a useful tool for urgent psychological intervention in the event of major workplace disasters.