• Journal of the Korea Safety Management & Science
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• v.2 no.4
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• pp.91-102
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• 2000

Nowadays, every kind of system is changed so complex and enormous, it is necessary to assure system reliability, product liability and safety. Fault tree analysis(FTA) is a reliability/safety design analysis technique which starts from consideration of system failure effect, referred to as “top event”, and proceeds by determining how these can be caused by single or combined lower level failures or events. So in fault tree analysis, it is important to find the combination of events which affect system failure. Minimal cut sets(MCS) and minimal path sets(MPS) are used in this process. FTA-I computer program is developed which calculates MCS and MPS in terms of Gw-Basic computer language considering Fussell's algorithm. FTA-II computer program which analyzes importance and function cost of VE consists. of five programs as follows : (l) Structural importance of basic event, (2) Structural probability importance of basic event, (3) Structural criticality importance of basic event, (4) Cost-Failure importance of basic event, (5) VE function cost analysis for importance of basic event. In this study, a method of initiation such as failure, function and cost in FTA is suggested, and especially the priority rank which is calculated by computer-aided decision analysis program developed in this study can be used in decision making determining the most important basic event under various conditions. Also the priority rank can be available for the case which selects system component in FMEA analysis.

• Journal of the Korean Society of Costume
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• v.64 no.3
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• pp.13-31
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• 2014

This study attempts to analyze relational structures among service failure-related variables after the moderation of fairness in the beauty service industry with the following purposes: First, it aims to review and investigate service failure & service recovery strategies, non-switching intentions after recovery, revisit intention, the intent to provide word-of-mouth recommendations and previous studies on service failure and recovery in the beauty service industry. Second, it targets the analysis of the role of fairness as a variable that moderates relations between service recovery strategies and post-recovery satisfaction in the beauty service industry. For this, the following research method was used: This study has investigated the effect of service failure and its recovery strategies (behavioral recovery strategy, psychological recovery strategy, monetary recovery strategy) on customer satisfaction for beauty service users and used the Structural Equation Model (SEM) to further analyze and verify the effect of the satisfaction on post-satisfaction behavior (non-switching intention, repurchase intention and the intent to provide word-of-mouth recommendations). The SEM was divided into a measurement model and structural model to determine if the model is appropriate and estimate the parameters of the path coefficient. In addition, this study examined to see if fairness (procedural fairness, distributive fairness and interactive fairness) works as a moderating variable while the service recovery efforts affect customer satisfaction. Then, the role of service recovery strategies, targeted to satisfy the customers who were dissatisfied because of service failure, were investigated. In addition, its effect on post-satisfaction behavior was analyzed from the structural aspect, and the moderating role was examined as well. Then, the role of the service recovery strategy, which can be used to satisfy dissatisfied customers, was examined, and the effect of the satisfaction on customer behavior was analyzed from a structural perspective. In addition, the moderating role of fairness was tested. As a result, this study is significant in that it helps service providers formulate service recovery-related strategies.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.39-49
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• 2017

The factor of safety (FOS) is commonly used as an index to quantitatively state the degree of safety of various rock structures. Therefore it is important to understand the definition and characteristics of the adopted FOS because the calculated FOS may be different according to the definition of FOS even if it is estimated under the same stress condition. In this study, four local factors of safety based on maximum shear stress, maximum shear strength, stress invariants, and maximum principal stress were defined using the Mohr-Coulomb and Hoek-Brown failure criteria. Then, the variation characteristics of each FOS along five stress paths were investigated. It is shown that the local FOS based on the shear strength, which is widely used in the stability analysis of rock structures, results in a higher FOS value than those based on the maximum principal stress and the stress invariants. This result implies that the local FOS based on the maximum shear stress or the stress invariants is more necessary than the local FOS based on the shear strength when the conservative rock mechanics design is required. In addition, it is shown that the maximum principal stresses at failure may reveal a large difference depending on the stress path.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.490-498
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• 2007

BGP route flap damping(RFD) was anecdotally considered to be a key contributor to the stability of the global Internet inter-domain routing system. However, it was recently shown that RFD can incorrectly suppress for substantially long periods of time relatively stable routes, i.e., routes that only fail occasionally. This phenomenon can be attributed to the complex interaction between BGP path exploration and how the RFD algorithm identifies route flaps. In this paper we identify a distinct characteristic of BGP path exploration following a single network event such as a link or router failure. Based on this characteristic, we distinguish BGP route updates during BGP path exploration from route flaps and propose a novel BGP route flap damping algorithm, RFD+. RFD+ has a number of attractive properties in improving Internet routing stability. In particular, it can correctly suppress persistent route flaps without affecting routes that only fail occasionally. In addition to presenting the new algorithm and analyzing its properties, we also perform simulation studies to illustrate the performance of the algorithm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.1
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• pp.1-8
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• 2007

People tend to spend more time in indoor spaces than before such as shopping malls and subway stations. As buildings become larger and more complex, people feel difficulty in finding their ways to destinations. Consequently, a means to provide better paths can aid people in reducing time for finding ways. Routing information in large indoor spaces is especially required in emergency cases as fire, power failure and terror. This study suggests to compute optimal paths using $A^*$ algorithm based on raster GIS data structure. The suggested method can be used either in daily lives for path provision or in emergency cases for evacuation, and is illustrated on a campus building.

• Journal of Information Technology Services
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• v.18 no.4
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• pp.171-190
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• 2019

This study comparatively analyzes the cases of CDMA (Code Division Multiple Access) and WIPI (Wireless Internet Platform for Interoperability) to find out the success and failure factors of technology policies in the field of mobile communication industry. For this purpose, the two cases are analyzed through a new analysis framework, which is made by combining System of Innovation with a range of variables derived from precedent studies, such as external environment, institutions, technological system, governance structure, and interactions of actors. The results of analysis show that in the CDMA case, the following factors led to success ; Korea made good use of the external opportunities in the early stage of digital communication technology and adopted a suitable governance structure for the technological system. Main actors in Innovation System had strong will for success and engaged in cooperative interaction. For the WIPI, however, the timing of technology policy was inappropriate and a unsuitable governance structure for technological system was chosen because of path dependence. The Innovation System failded to respond efficiently to the situation where conflicts among actors had intensified, US trade pressure had increased and innovative smartphones emerged. The results of this study provide the practical implications for the success of technology policy; namely it is important to choose a governance structure that suits the external environment and characteristics of technology and to activate cooperative interactions among actors in Innovation System.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.6
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• pp.770-778
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• 2012

In this paper, we propose a multi-path construction scheme to improve the survivability of a multicast session in military hybrid networks. A military hybrid network consists of a static backbone network and multiple mobile stub networks where some nodes are frequently susceptible to be disconnected due to link failure and node mobility. To improve the survivability of multicast sessions, we propose a construction scheme of ${\kappa}$ redundant multi-paths to each receiver. In order to take account of different characteristics of static and mobile networks, we propose quite different multi-path setup approaches for the backbone and stub networks, respectively, and combine them at the boundary point called gateway. We prove that our proposed scheme ensures that each receiver of a multicast session has ${\kappa}$ redundant paths to the common source. Through simulations, we evaluate the performance of the proposed schemes from three aspects : network survivability, recovery cost, and end-to-end delay.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.249-252
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• 2005

Recently, as the industrial demand for small quantity batch production of sheet metal components, the application of dieless forming technology to production of these component rise with the advantages of the reduction in manufacturing cost and time. In dieless forming processes, the determination of moving path of tool plays an important role in producing successfully formed parts. In order to obtain the optimized moving path of tool avoiding forming failure, it is necessary to examine the forming limit of sheet material. Therefore, in this study, as the new criterion to evaluate the formability of sheet material in dieless forming processes FDD(feeding depth diagram) with respect to feeding depth and punch diameter is proposed. Thus, the FDD for the sheet materials of STS304 and Ti-grade2 were obtained from a series of FDT(feeding depth test). In addition the possibility of the application of FLD in judging forming severity in dieless forming processes was investigated by comparing the results of FE analyses based on FLD and experimental FDT.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.2
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• pp.62-68
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• 2019

The growth and employment effects of R&D investment were analyzed according to business size, export value and manufacturing sectors so as to suggest improvement directions for effective industry policies. The effect of R&D investment was considered simultaneously from the two perspectives of growth and employment effect, and the causality analysis was carried out by using a path analysis. The result of the path analysis confirmed significant differences in the growth effect of R&D investment depending on business size. However, the effect of increasing employment was difficult to obtain statistically significant results for any various combinations of business size and export value. This is a mixture of directions for the effects of R&D investment on employment, which could be due to the failure to consider appropriate time lags between investment and effect. Efficiency analysis by industry sectors confirmed significant differences in efficiency depending on business size, but differences depending on export value were difficult to identify. In order to derive improvement policy by industry sector according to business size and export value, the direction of selective support policy and universal support policy was derived for six industry groups by combining the return to scale in the efficiency analysis and R&D concentration. Hirschman-Herfindahl index is used for calculating R&D concentration.

• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.199-202
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• 2001

In this paper, we proposed and analyzed a new class of irregular fault-tolerant multistage interconnection network named as Extended-QT(Quad Tree) network. E-QT network is extended QT network. A unique path MIN usually is low hardware complexity and control algorithm. So we proposes a class of multipath MIN which are obtained by adding self-loop auxiliary links at the a1l stages in QT(Quad Tree) networks so that they can provide more paths between each source-destination pair. The routing of proposed structure is adaptived and is based by a routing tag. Starting with the routing tag for the minimum path between a given source-destination pair, routing algorithm uses a set of rules to select switches and modify routing tag. Trying the self-loop auxiliary link when both of the output links are unavailable. If the trying is failure, the packet discard. In simulation, an index of performance called reliability and cost are introduced to compare different kinds of MINs. As a result, the prouosed MINs have better capacity than 07 networks.