• 한국전자통신학회논문지
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• 제11권12호
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• pp.1187-1192
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• 2016

수중 MANET의 설계, 구축 및 운용에서 전송성능의 측정 및 분석은 네트워크 차원의 전송 파라미터를 중심으로 수행됨에 따라 성능 분석 결과가 네트워크 수준의 성능에 국한되고 있어 사용자 수준의 전송품질과 관련한 전송성능을 분석 고찰하기에는 미흡한 점이 있다. 본 논문에서는 수중 MANET에서 네트워크 수준의 전송성능 분석의 단점을 보완하고자 사용자 수준에서 요구되는 응용트래픽 관점에서 전송성능을 분석한다. 수중 MANET에서 활용도가 증가할 것으로 예상되는 음성트래픽을 대상으로 전송성능을 분석하고, MOS, CCR 및 EED 등의 음성 전송품질 요구조건에 적합한 수중 MANET 조건을 제시한다. 본 연구는 NS-2를 기반으로 구축된 컴퓨터 시뮬레이션을 사용하여 수행하며, 음성 트래픽으로는 VoIP 규격을 사용한다.

• 한국정보시스템학회지:정보시스템연구
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• 제29권3호
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• pp.197-214
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• 2020

Purpose This study examines the influence of product development competence and IT competence on new product development (NPD) performance in the context of Korean companies. To achieve this goal, this study presents and empirically tests a model of how NPD competence and IT competence can be exploited to positively influence NPD performance through convergence capabilities. Design/methodology/approach The NPD competence are based on the research construct developed by Zhang et al. (2013). IT competence is based on the research construct developed by Lu and Ramamurthy(2011) and the NPD performance are based on the performance construct developed by Sivadas and Dwyer (2000). To complete the investigation, we conducted a survey from Korean 1000 big companies, which enrolled in Korean stock market. Randomly contacted 171 Korean companies, including firms of all sizes and types. To test our hypotheses, structured equation model (SEM) with partial least squares (PLS) method was employed. Findings The findings indicate that NPD competence and IT competence are antecedent to convergence capabilities, while IT competence is higher influence than NPD competence. Also, convergence capabilities has very significant relationship with NPD performance. This study provides a better understanding of the relationship between NPD competence, IT competence, convergence capabilities, and NPD performance. So companies should focus on improving NPD and IT competence on NPD performance through convergence capabilities.

• Computers and Concrete
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• 제20권5호
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• pp.573-582
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• 2017

Chloride-induced cover cracking will aggravate the performance deterioration for RC structures under the chlorideladen environment, which may endanger the safety of structures and occupants. Traditional design method cannot ensure that a definite performance is satisfied. To overcome the defects, a study on the performance-based design method was carried out in this paper. Firstly, the limit state functions were established for the corrosion initiation and cover cracking. Thereafter, the uncertainty analysis was performed to study the effects of random factors on the time-dependent performances. Partial factor formulae were deduced through the first-order reliability method for performance verification. Finally, an illustrative example was presented and the sensitivity of cover depth to other parameters was carried out. It is found that the uncertainties of the random variables have great effects on the required cover depth. It is demonstrated that the performance-based design method can ensure that the target performance can be satisfied and support to formulate a rational maintenance and repair strategy for RC structures under the chloride environment.

• 한국해양공학회지
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• 제37권4호
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• pp.129-136
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• 2023

To evaluate manoeuvring performance of merchant ships, the mathematical modeling group (MMG) or computational fluid dynamics (CFD) simulations are used. However, it is difficult to use the MMG to evaluate the manoeuvring performance of fishing vessels, thus research using CFD simulations is necessary. Also, since the course-changing and turning ability is crucial in fishing operations, a rudder design suitable for fishing vessels is necessary. This study designs a rudder using National Advisory Committee for Aeronautics (NACA) airfoil sections and evaluates its manoeuvring performance. A CFD model is used to evaluate the manoeuvring performance of the fishing vessel, and turning and zig-zag tests are conducted. The effectiveness of using CFD simulations based on Reynolds averaged Navier-Stokes equations to assess the manoeuvring performance of fishing vessels was validated. No significant difference was found in the manoeuvring performance for hull forms and rudder designs for course-changing ability. However, the original hull form showed superior turning performance. Among five rudders with varying aspect ratios and shapes, the rudder with 5.5% aspect ratio had the best turning performance. Regarding the rudder design for fishing vessels, NACA airfoil was employed, and a rudder aspect ratio of 5.5% based on the immersed hull side area is recommended.

• 무역상무연구
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• 제65권
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• pp.161-179
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• 2015

The main objective of this study is to examine the mediating effect of 'international entrepreneurship' on the relationship between the determinants related to export and export performance. Data was collected from a survey of 200 exporting firms in Gwangju, Korea. The results of the study are as follows ; First, 'international entrepreneurship' are produced a mediating effect when the determinants affect export performance. Second, Resource-based factors and Industry organization factors have a positive impacts on export performance. However, relationship factor as a determinant does not have statistically significant correlation to export performance. Accordingly, in orer to enhance export performance, exporting firms in Korea should try more to prepare for resource-based factors and industry organization factors as determinants. In addition to these, if CEOs of exporting firms are equipped with international entrepreneurship spirits, they can increase the performance of their exporting firms. So they have to manage their exporting firms very strategically so that they can make their firms' export performance better and better.

• 대한기계학회논문집B
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• 제29권3호
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• pp.409-416
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• 2005

We need to develop a on-line thermal performance analysis system for nuclear power plant to determine performance status and heat rate of turbine cycle. We have developed PERUPS(PERformance Upgrade System) to aid the effective performance analysis of turbine cycle. Procedures of performance calculation are improved using several adaptations from standard calculation algorithms based on PTC(Performance Test Code). Robustness in the on-line performance analysis is increased by verification & validation scheme for measured input data. The system also provides useful web interfaces for performance analysis such as graphic heat balance of turbine cycle and components, turbine expansion lines, automatic generation of analysis report. The system was successfully applied for YongGwang nuclear plant unit #3,4.

• 한국경영과학회지
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• 제28권3호
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• pp.67-79
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• 2003

An efficient mobility management for mobile stations plays an important role in mobile communication networks. Even though many a mobility management schemes have been proposed, most of mobile communication networks adopt the mobility scheme based on zone-based registration. This paper studies the mobility management scheme that combines zone-based registration and 2-step selective paging. We assume cell by cell registration area, not ring by ring registration area of previous studies, and set up a new mobility model based on 2-dimensional random walk model considering the characteristic of zone-based registration to evaluate its performance exactly. We provide numerical results using proposed model to demonstrate the performance of zone-based registration and 2-step selective paging under various circumstances.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2003년도 춘계종합학술대회논문집
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• pp.449-453
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• 2003

In this paper, we evaluate the performance of zone-based registration, distance-based registration and distance-based registration considering call arrival. We propose the mobility model, which can be used to analyze the performance of three registration schemes. Numerical results show that zone-based registration needs less number of registration than distance-based registration. On the other hand, the registration load of the distance-based registration is equally distributed to all cells in a location area. However, the registration load of the distance-based registration considering call arrival is similar to that of zone-based registration and equally distributed to all cells in a location am Therefore, the proposed scheme can be effectively used restricted radio resources.

• Journal of Communications and Networks
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• 제16권6호
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• pp.645-655
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• 2014

Latency, an identified element of Internet protocol (IP) mobility protocol execution, can reduce handover performance in mobile networks. Although the performance can be improved by applying an effective network-based IP mobility scheme in place of the traditional host-based alternatives, the existing inter-domain extensions of network-based IP mobility continue to suffer from an extended handover latency. This paper proposes a new inter-domain network-based IP mobility scheme based on node movement prediction. The proposed scheme accelerates the handover by preparing the future domain of the mobile node in a proactive manner. Analytical and simulation-based evaluations confirm improved performance of the proposed scheme in terms of handover latency and packet loss compared with existing schemes.

• 의학교육논단
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• 제13권1호
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• pp.13-23
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• 2011

Competency and competency-based education are topics of great interest to educators and administrators at most stages of undergraduate and postgraduate medical training. A competency-based approach in medical setting has been valued as a more effective way to strengthen learners' performance compared to the traditional education program. This article aims to explore theoretical and practical possibilities and limitations of competency-based medical education. We approached the topic in 3 gradual steps: the comprehension of background of competency-based education, the conceptual understanding of competency in professional education, and the exploration of possibilities and limitations of competency-based medical education. The last step of analysis was performed in three dimensions: educational objectives, references to judge performance, and performance evaluation criteria. In conclusion, we suggest 4 factors which need to be considered to implement a competency-based medical education.