• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.127-134
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• 2002

This study present a direct steering system using rack and pinion for ultra-small vehicles. The traditional small vehicles for special use had the limitation of space by reason of short wheel tread. These vehicles has adopted a indirect steering system or a center arm system for steering. The disadvantages of these system were deterioration of gear efficiency and increase of parts. For direct-linkage to both knuckles, steering system is made up of out-side tie rods, tie-rod ends, and gear box. Thus, the proposed system has a minimum number of parts. The experimental results show a maximum efficiency at minimum steering angle and a minimum clearance circle. These effects were accomplished by adopting a Ackerman-Jantaud theory.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.942-947
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• 2006

In this paper, a new feature representation technique called Improved 2-directional 2-dimensional direct linear discriminant analysis (Improved $(2D)^2$ DLDA) is proposed. In the case of face recognition, thesmall sample size problem and need for many coefficients are often encountered. In order to solve these problems, the proposed method uses the direct LDA and 2-directional image scatter matrix. Moreover the selection method of feature vector and the method of similarity measure are proposed. The ORL face database is used to evaluate the performance of the proposed method. The experimental results show that the proposed method obtains better recognition rate and requires lesser memory than the direct LDA.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.43-44
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• 2006

The performance of the direct adaptive time-delay filter depends on the select time-delay. In this paper, the authors introduce a new scheme to adapt the time-delay which is to be used in conjunction with the direct adaptive command shaping for the improved vibration suppression in flexible motion system. In order to formulate the time-delay adaptation scheme, the authors have analyzed the effect of the time-delay value on the performance of the direct adaptive command shaping filter. By modifying the direct adaptation formula based on the analysis result the authors have established a set of equations to adapt the time-delay toward the optimal value. Simulation results show the effectiveness of the proposed time-delay adaptation approach for the improved vibration suppression.

• Journal of Korea Technology Innovation Society
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• v.8 no.3
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• pp.1225-1249
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• 2005

This study aims at investigating whether foreign direct investment plays a role as a channel of international technology diffusion. We used the annual panel data from 1980 to 2002. The nonstationary panel techniques, in particular group mean panel FMOLS(fully modified OLS) was exploited as an empirical methodology in order to tackle the heterogeneity between members and low frequency. The empirical results show that inflow direct investments lead to an increase in total factor productivity and economic growth. Also outflow direct investments contribute to an higher total factor productivity and economic growth. These results confirms that both inflow and outflow direct investments are important channels for international technology diffusion or spillover.

• The Journal of Information Systems
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• v.12 no.1
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• pp.47-66
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• 2003

This study was examined the relationship between the exogenous and endogenous variables in our model to measure ERP system performance using path analysis. The exogenous variables are system quality, user participation, user training, top management support and self-efficacy, and the endogenous variables are system usage, user satisfaction, and work efficiency. The results of the study are shown as follows. First, all the exogenous variables in our model have a direct effect on user satisfaction, and system quality, training, and self-efficacy have a direct effect on system usage. Second, system usage has a direct effect on user satisfaction and user satisfaction has a direct effect on work efficiency. The findings show that the exogenous variables in the model are important to increase ERP implementation success.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.2
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• pp.67-72
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• 2005

This paper presents a method to select contingency ranking considering voltage security problems in power systems. Direct method which needs not the detailed knowledge of the post contingency voltage at each bus is used. Based on system operator's experience and knowledge, the membership functions for the MVAR mismatch and allowable voltage violation are justified describing linguistic representation with heuristic rules. Rule base is used for the computation of severity index for each contingency by fuzzy inference. Contingency ranking harmful to the system is formed by the index for security evaluation. Compared with 1P-1Q iteration, this algorithm using direct method and fuzzy inference shows higher computation speed and almost the same accuracy. The proposed method is applied to model system and KEPCO pratical system which consists of 311 buses and 609 lines to show its effectiveness.

• Journal of Information Technology Services
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• v.14 no.4
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• pp.31-44
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• 2015

Local governments in Korea are involved in three types of online shopping sites : 'direct operation', 'outsourced operation', and 'sales agency.' They are different in terms of the site operator and the charging mechanism among a local government, the site operator, and local producers. This study analyzes their differences in site traffic, local producers' participation, promotion, and partnership. The results from the investigation of 72 shopping sites are the following. First, shopping sites of the 'direct operation' type and the 'outsourced operation' type show significantly higher participation of local producers. Second, the 'marketing agency' type has significantly higher number of promotional activities than the 'oursourced type' which has significantly higher number than the 'direct operation' type. Third, the number of partnerships in the 'marketing agency' type is the highest. The 'direct operation' type is the second and significantly higher than the 'outsourced type.' On the basis of the analysis results, this paper suggests an incubation ecosystem model as a better way of involvement by local governments in online shopping sites.

• Coupled systems mechanics
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• v.4 no.4
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• pp.317-336
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• 2015

The present paper deals with the analysis of water tank with elastic separator wall. Both fluid and structure are discretized and modeled by eight node-elements. In the governing equations, pressure for the fluid domain and displacement for the separator wall are considered as nodal variables. A method namely, direct coupled for the analysis of water tank has been carried out in this study. In direct coupled approach, the solution of the fluid-structure system is accomplished by considering these as a single system. The hydrodynamic pressure on tank wall is presented for different lengths of tank. The results show that the magnitude of hydrodynamic pressure is quite large when the distances between the separator wall and tank wall are relatively closer and this is due to higher rotating tendency of fluid and the higher sloshed displacement at free surface.

• Kyungpook Mathematical Journal
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• v.60 no.4
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• pp.673-682
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• 2020

For the recently defined notion of strongly lifting modules, it has been shown that a direct sum is not, in general, strongly lifting. In this paper we investigate the question: When are the direct sums of strongly lifting modules, also strongly lifting? We introduce the notion of a relatively strongly projective module and use it to show if M = M1 ⊕ M2 is amply supplemented, then M is strongly lifting if and only if M1 and M2 are relatively strongly projective and strongly lifting. Also, we consider when an arbitrary direct sum of hollow (resp. local) modules is strongly lifting.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.2
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• pp.97-111
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• 1995

In this paper, we investigate path compensation scheme for the machining errors due to tool deflection in 2D contour machining. The significance of the deflection error is first shown by experiments, and a direct compensation scheme is sought. In the presented scheme, the tool path is evaluated and correcte based on the instantaneous deflection force model, until the desired contour can be obtained under the presence of tool deflection in actual machining. In the sense that the developed method estimates and compensates the machining errors via modifying the tool path, it is distinguished from the previous approach based on geometric simulation and cutting simulation. Further, it can be viewed as a direct and active method toward direct shape control in CNC machining. Simulation results are included to show the validity and adequacy of the path-modification scheme under various cutting conditions.