• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.147-152
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• 2017

The external reactor vessel cooling (ERVC) is well known strategy to mitigate a severe accident at which nuclear fuel inside the reactor vessel is molten. In order to compare the heat removal capacity of ERVC between the nuclear reactor designs quantitatively, numerical method is often used. However, the study for ERVC using computational fluid dynamics (CFD) is still quite scarce. As a validation study on the numerical prediction for ERVC using CFD, the subcooled boiling flow and natural circulation of coolant at the ULPU-V experiment was simulated. The commercially available CFD software ANSYS-CFX was used. Shear stress transport (SST) model and RPI model were used for turbulence closure and wall-boiling, respectively. The averaged flow velocities in the downcomer and the baffle entry under the reactor vessel lower plenum are in good agreement with the available experimental data and recent computational results. Steam generated from the heated wall condenses rapidly and coolant flows maintains single-phase flow until coolant boils again by flashing process due to the decrease of saturation temperature induced by higher elevation. Hence, the flow rate of coolant natural circulation does not vary significantly with the change of heat flux applied at the reactor vessel, which is also consistent with the previous literatures.

• Knowledge Management Research
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• v.14 no.3
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• pp.37-54
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• 2013

Technology standards have gained importance as global market becomes more competitive. Since a technology acknowledged as a standard brings significant benefits to the developer firm, firms in the IT industry tend to pursue standardization for the technology, being it proprietary or open. However, the paths or strategic implications are seldom discussed in academia. Therefore, our study uses iPhone of Apple, one of the proprietary standards successes, to further understand corporate strategies over two standard choices. Our case study suggests that iPhone's entry timing was optimal for creating a new mobile environment. Design excellence and user-friendly interface increased networking effects and switching costs among consumers. Apple developed independent mobile operating system (iOS) through improvement on the existing operating system. During the process, Apple chose proprietary standard and, by installing the same UX on its sibling products such as iPod Touch or iPad, overcame the subsequent problems that might arise from the limited use of iOS. Based on the capability of concurrently developing both hardware and software, Apple connected operating system, machine, and contents, which deems to contribute to its proprietary standards success. We argue that this strategy should be considered for firms which plan proprietary standard strategy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.6
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• pp.1627-1648
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• 2012

We propose an adaptive method for detecting plagiarized pairs from a large set of source code. This method is adaptive in that it uses an adaptive algorithm and it provides an adaptive threshold for determining plagiarism. Conventional algorithms are based on greedy string tiling or on local alignments of two code strings. However, most of them are not adaptive; they do not consider the characteristics of the program set, thereby causing a problem for a program set in which all the programs are inherently similar. We propose adaptive local alignment-a variant of local alignment that uses an adaptive similarity matrix. Each entry of this matrix is the logarithm of the probabilities of the keywords based on their frequency in a given program set. We also propose an adaptive threshold based on the local outlier factor (LOF), which represents the likelihood of an entity being an outlier. Experimental results indicate that our method is more sensitive than JPlag, which uses greedy string tiling for detecting plagiarism-suspected code pairs. Further, the adaptive threshold based on the LOF is shown to be effective, and the detection performance shows high sensitivity with negligible loss of specificity, compared with that using a fixed threshold.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.157-159
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• 2014

전술데이터링크는 전장 환경에서 모든 플랫폼들을 네트워크를 통해 하나로 묶어 전쟁 효과를 극대화할 수 있는 기반이 되는 통신 기술이다. 이러한 전술데이터링크의 원활한 운영을 위해 플랫폼간 시간 동기가 필수적이며, 대부분 GPS(Global Positioning System)를 사용하고 있다. 전세계적으로 가장 널리 사용되고 있는 전술데이터링크인 Link-16 에서는 네트워크에 가입하면서 NTR(Network Time Reference) 과의 시간을 동기화하는 절차를 제공한다. 이러한 시간 동기 절차는 대략적인 동기와 정밀한 동기의 두 단계로 구분된다. 대략적인 동기는 프레임이 시작하는 첫 타임 슬롯에서 주변 노드로부터 IEM(Initial Entry Message)을 수신하여 전송 시간만큼의 오류를 포함하는 시간 동기 방식이다. 본 논문에서는 모의 실험을 통해 IEM 을 전송하는 노드의 거리에 따른 메시지의 충돌 확률을 구하고, 그 충돌 확률에 따라 시간 동기에 소요되는 시간으로 Link-16 의 시간 동기 성능을 분석하였다.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.599-607
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• 2022

Recently, there has been a steady decrease in the proportion of the construction sector among Korean engineering firms. Thus it is essential for Korean engineering firms in the construction sector, which lack experience in overseas ventures, to identify and improve their competitiveness for successful overseas expansion. Therefore, in this study, changes in Korean engineering firms' capabilities for the last decade were analyzed to promote entry into overseas road and water resource engineering markets. Competency factors that require urgent improvement were derived based on Importance-Performance Analysis (IPA) as a tool for quantitative measurement. As a result, the factor that shows low performance compared to the importance is an overall understanding of the target country in the road and water resource areas. Knowledge of regulatory issues on design, the ability of time management software, and knowledge of the regulatory problems on construction safety are also insufficient. This study can be used as a research methodology to identify competitiveness that Korean engineering firms have to strengthen when they advance into overseas markets in roads, water resources, and other areas.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1207-1214
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• 2014

Recently it has become easier to figure out cargo positional information by using GPS(Global Positioning System) and wireless communication technology. The acceleration of globalization in the shipping logistics is ever more increasing the need to provide visibility, traceability and real time informations of entry, departure of vessel including cargo and status of logistic vehicle entry into each logistic base. Providing such positional information to logistics party by using wireless communication technology can bring effective operation of supply chain and reduction in logistics costs. In the previous paper, I suggested a global location tracking system based on GPS data in global shipping logistics by means of software using GPS data. However, the previous system had a problem of being inadequate to figure out a real time location movement information and was unsatisfactory on quickly searching and checking the location of global logistics hubs according to the longitude and latitude coordinates. Hence, in this paper, I suggest a real-time location tracking system that provided real-time location of the container cargos and logistics hubs can be searched quickly according to the GPS coordinates in global shipping logistics.

• Imaging Science in Dentistry
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• v.42 no.3
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• pp.139-146
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• 2012

Purpose: An individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement. Materials and Methods: A resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated. Results: The deviation of the entry point and angulation of the central axis in the reference plane were $0.47{\pm}0.27$ mm, $0.57{\pm}0.23$ mm, and $0.64{\pm}0.16^{\circ}$, $0.57{\pm}0.15^{\circ}$, respectively. However, for the two different angulations in each group, the $20^{\circ}$ angulation showed a greater error in the deviation of the entry point than did the $10^{\circ}$ angulation. Conclusion: The CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.249-257
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• 2022

This paper presents an improved computational framework for the direct-solution-based finite element tearing and interconnecting (FETI) algorithm. The FETI-local algorithm is further improved herein, and localized Lagrange multipliers are used to define the interface among its subdomains. Selective inverse entry computation, using a property of the Boolean matrix, is employed for the computation of the subdomain interface stiffness and load, in which the original FETI-local algorithm requires a full matrix inverse computation of a high computational cost. In the global interface computation step, the original serial computation is replaced by a parallel multi-frontal method. The performance of the improved FETI-local algorithm was evaluated using a numerical example with 64 million degrees of freedom (DOFs). The computational time was reduced by up to 97.8% compared to that of the original algorithm. In addition, further stable and improved scalability was obtained in terms of a speed-up indicator. Furthermore, a performance comparison was conducted to evaluate the differences between the proposed algorithm and commercial software ANSYS using a large-scale computation with 432 million DOFs. Although ANSYS is superior in terms of computational time, the proposed algorithm has an advantage in terms of the speed-up increase per processor increase.

• Journal of KIISE:Software and Applications
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• v.33 no.12
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• pp.1090-1102
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• 2006

This paper suggests a new algorithm for detecting the plagiarism among a set of source codes, constrained to be functionally equivalent, such are submitted for a programming assignment or for a programming contest problem. The typical algorithms largely exploited up to now are based on Greedy-String Tiling, which seeks for a perfect match of substrings, and analysis of similarity between strings based on the local alignment of the two strings. This paper introduces a new method for detecting the similar interval of the given programs based on an adaptive similarity matrix, each entry of which is the logarithm of the probabilities of the keywords based on the frequencies of them in the given set of programs. We experimented this method using a set of programs submitted for more than 10 real programming contests. According to the experimental results, we can find several advantages of this method compared to the previous one which uses fixed similarity matrix(+1 for match, -1 for mismatch, -2 for gap) and also can find that the adaptive similarity matrix can be used for detecting various plagiarism cases.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.487-493
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• 2014

A geographic survey, which requires much of working hours in the digital mapping process, is consisted with the complementary survey and the attribute survey of topography and topographic features, and depended on the field survey. In previous research, using the location-based image had been recommended for diminishing the workload of field survey and post processing. For this research, we have developed the hardware and software for gathering and processing the location-based images with referencing results from the previous research. Those Geographic surveys were performed using developed system on 1/5,000 map sheets for Si and Gun area, respectively. The results have been evaluated as the mobile geographic survey system were able to replace the large part of field survey, and also the working hours were decreased by 37.5% at Si area. However, the complementary survey was needed for the attributes of topography and topographic features that were occluded by the parked vehicles or located in the areas without entry of vehicles.