• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.30-35
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• 2008

As demands for being economical, precise drilling process is on the increase. Therefore, the objective of this study is to develop a step cutter that can be controllable through micro dimension and can be changed from separate manufacturing processes of drilling and boring into an integrated one. In order to attain this object the step cutter is designed with a 3D geometric modeling and the design could be modified easily by using parametric modeling methodology. Also, collision is not occurred during manufacturing process because of cutting simulation. The step cutter is assembled by parts made up of 5-axis machining and sintering. Validation tests are accomplished. They show that developed cutter has characteristics such as reduction of machining time as well as the good surface roughness of the machined hole. Indeed, reliability could be obtained from a durability test.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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• pp.806-811
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• 2001

The analysis and control algorithm of a new type unsymmetrical self-bearing step motor is presented. The motor actuator is used for both motor and bearing functionality without any redundant coil windings or redudant electromagnets for bearing functionality. Self bearing step motor layout and control current generation method for unsymmetrical position of electromagnets are described. This new current generation method without additional current for bearing functionality leads to minimize the power loss. As the result of the unbalance response approach, the constant torque is possible, even though the bearing functionality is added or not.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.20-25
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• 2008

The finite element analysis for porous media is severe job because constituents have different physical peoperties, and element's continuity and stability should be considered. Thus, we propose the new mixed finite element method in order to overcome the problems. In this method, multi time step, remeshing step, and sub iteration step are introduced. The multi time step and remeshing step make it possible to satisfy a stability and an accuracy during sub iteration in which global time is determined. Finally, the proposed method is compared with the ABAQUS(2007) software and exact solution(Schiffman 1967) through two dimensional consolidation model.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.285-288
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• 2005

In this paper, we propose a two step Binary Exponential search algorithm for rapid acquisition time of UWB(Ultra Wide Band) signal on UWB communication systems. Previous proposed timing acquisition algorithm is searching whole frame that consist of the number of n Bins to terminate search, however this paper proposed two step Binary Exponential search algorithm can achieve remarkable reduction of UWB signal acquisition time as limiting search group. Proposed search algorithm is consisting of search group establishment step and Bit Reversing of search group establishment step.

• Korean Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.203-214
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• 1996

An information sharing system, namely World Design View, is developed for browsing product design data on the World Wide Web environment. For the last few years information sharing has been rapidly emerging as an important research issue in the areas of concurrent engineering, product data management, virtual manufacturing, and so on. Since we are mainly concerned with product development, the key information that needs be communicated and shared is product data. The developed system puts the major advantages of STEP, OODB, and VRML together. The STEP standard provides a consistent data exchange format and application interfaces among different CAD/CAM systems. OODB is efficient and effective in dealing with complex data structures often found in engineering applications. Virtual worlds for 3-D product models can be created by VRML which is networked via the global Internet and hyperlinked with WWW. The World Design View system can support for members of virtual design teams, possibly distributed all over the world, to share 3-D shape information quickly and easily.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.126-129
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• 1991

The effect of each tooth for optimal design of Hybrid permanent magnet step motor is presented on this paper. For this consideration, Hybrid permanent magnet step motor was designed in the first consideration tooth structure on the stator and the rotor and poles structure, as number of teeth on the stator and the rotor and slot depth and pitch of teeth, simulated by AutoLISP. During actual rotating, a chracteristic of Hybrid permanent magnet step motor which designed by AutoLISP program is considered. A chracteristic of Hybrid permanent magnet step motor is considered in change each variable, also. As a result, it was found that characteristic of Hybrid permanent magnet step motor changed in accordance with tooth structure and number of teeth and optimal design is possible by AutoLISP.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.1
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• pp.65-70
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• 2002

In this thesis, we realized tracking system for the purpose of receiving performance improvement of KOREASAT's signal in Korea peninsula. Using Scan-mode antenna point out receivable area without position information sensor and using step-track algorithm reach to peak level. Furthermore, the performance of the completed system was verified by physical experiments that directly receives satellite signal. And decided the optimal size of steps for tracking speed and structure of the system by reiterative approach experiments.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.91-94
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• 2001

Recently a constant-norm constraint equation-error method was proposed to solve the bias problem in adaptive IIR filtering. However, the method adopts a fixed step-size and thus results in slow convergence for a small step-size and significant misadjustment error for a largestep-size. In this paper, we propose a variable step-size (VSS) algorithm that greatly improves convergence properties of the constant-norm constraint equation-error method. The analysis and the simulation results show that the proposed method indeed achieves both fast convergence and small misadjustment error.

• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.809-824
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• 2002

we propose two methods which separate the variable selection step and the split-point selection step. We call these two algorithms as CHITES method and F&CHITES method. They adapted some of the best characteristics of CART, CHAID, and QUEST. In the first step the variable, which is most significant to predict the target class values, is selected. In the second step, the exhaustive search method is applied to find the splitting point based on the selected variable in the first step. We compared the proposed methods, CART, and QUEST in terms of variable selection bias and power, error rates, and training times. The proposed methods are not only unbiased in the null case, but also powerful for selecting correct variables in non-null cases.

• Journal of the Korean housing association
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• v.10 no.2
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• pp.247-257
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• 1999

This study is aimed to propose the evaluation model of forecasting visual quality of apartment buildings, which would be a useful tool to make the architectural concepts corresponding to user needs. This study was carried out through the four-step experiments as follows. The first step is to take the user's visual evaluation construct. To do this, the 22 adjective phrases were extracted, which were applicable to all apartment buildings. The second step is to analyze the user's visual preference, which is measured by the user's psychological quantity on the apartment buildings by S. D.(Semantic Differential) Method. The third step is to analyzethe five psychological-factors obtained from the Factor Analysis. The perceptual images on the 41 experimental subjects were checked up through evaluating and analyzing the factor scores of each subjects for each psychological-factor. The fourth step is to analyze, the similarity of various characters in a building, which is mirrored on the user's psychological quantity and how buildings are grouped by it.