• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.65-74
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• 2007

Virtual manufacturing (VM) is a powerful technology for developing a new product, new equipment and new manufacturing system, and three-dimensional (3D) simulation is a core technology in VM. 3D simulation involves both mechanical simulation and discrete event simulation. This paper introduces a case study of implementing 3D simulation for developing an automatic assembly line in a Korean optical factory. This factory produces a lens module that is the part of a phone-camera. 3D simulation technology is applied from the early stage of development. In the conceptual design and the initial design phases for individual equipment, 3D mechanical simulation using $CATIA^{(R)}$ and $IGRIP^{(R)}$ is conducted. 3D discrete event simulation with $QUEST^{(R)}$ is applied to the detailed design of the equipment and of the whole system. The focus of the simulation is to verify the technical and economical feasibility of the new automatic system. As a result, the takt time is reduced to the quarter of the manual system, and the number of workers in a line is reduced tremendously.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.355-361
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• 1999

The aim of this study is to develop the water quality simulation model (BAYQUAL) that deal with the physical, chemical and biological aspects of fate/behavior of pollutants in the bay. BAYQUAL is a two dimensional, time-variable finite element water quality model based on the flow simulation model in bay(BAYFLOW). The algorithm is composed of a hydrodynamic module which solves the equations of motion and continuity, a pollutnat dispersion module which solves the dispersion-advection equation. The applicability and feasibility of the model are discussed by applications of the model to the Kwangyang bay of south coastal waters of Korea. Based on the field data, the BAYQUAL model was calibrated and verified. The results were in good agreement with measured value within relative error of 14% for COD, T-N, T-P. Numerical simulations of velocity components and tide amplitude(M2) were agreed closely with the actual data.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.478-483
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• 2000

In this study to cope with the decreasing product's life-cycle a virtual simulator to realize the simulation environment similar to a real manufacturing line is developed. The developed simulator plays a role in reducing the product conversion time by alternating manufacturing components and work plans on the simulation as manufacturing lines change and actuating a virtual manufacturing lines change and actuating a virtual manufacturing line before a real production. The developed simulator realized a virtual manufacturing line on the simulation using various manipulators and work cells as manufacturing components. Also It can be shown that the simulator can cope with rapid change of a manufacturing line by developing a interface that a separate process is managed for each manufacturing module and a manipulator component and a work cell are changed for a user to become convenient to teach tasks of each work module. using Microsoft Visual C++ 6.0 and OpenGL of Silicon Graphics for libraries to realize 3-dimensional graphic and constructing a database system, a hybrid type of hierachical and relational model to develop a progra that has efficiency and standardization.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.21-31
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• 1998

This study described computer aided die design system for cold forging of non-axisymmetric parts. To design the die of cold forging. an integrated approach based on a rule-base system and commercial F. E. code were adopted. This system is implemented on the personal computer and its environment is a commercial CAD package named as AutoCAD. The system includes four modules. In the initial data input module, the variables which are necessary to design of die are inputted by user and die material are selected from the database. In the analysis and redesign module, stress distrubution action on the designed die is analyzed by commercial FEM code NISA II. The designed die is modified to prevent failure in both states of stress free and pressurizing. The developed system provides powerful capabilities for die design of non-axisymmetric parts.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.9
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• pp.1-12
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• 1998

We have implemented receiver for a 3 Dimensional Phased-Array Radar detecting the azimuth angle, the altitude, the range of a target on real time. This system consists of high frequency module, which protects receiver and controls sensitivity, intermediate frequency module, monopulse detector, IQ phase detector, AGC controller. A two-channel receiver with same function is implemented for increasing accuracy of target altitude data by amplitude comparison monopulse method. The TSS sensitivity of the receiver is -98dBm. The bandwidth of the receiver is 500 MHz. We can control the system gain manually by 100 dB when be AGC off. The gain and phase unbalance of two channels is 5 dB and 30 degree, respectively. The image rejection rate of the IQ detector is 30 dB. We used duroid substrate and package- type device.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.3
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• pp.25-35
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• 1999

LTCC (Low Temperature Cofired Ceramic) or LTCC-M (Low Temperature Cofired ceramic on Metal) technology is one of MCM-C (Multichip Module on Ceramic) technologies and becomes to be widely used in consumer, RF and automotive electronics. As green sheets for LTCC are cofired below $1000^{\circ}C$ in comparison with those for HTCC (High Temperature Cofired Ceramic), high conductivity metal traces such as gold, silver and copper can be used. The dimensional stability in LTCC-M technology enables embedded passives to be integrated inside modules, which enhances the electrical performance and increases the reliability of the modules. Coefficient of thermal expansion and dielectric constant can be controlled by changing composition and heating profile for cofiring. In this technical review, LTCC and LTCC-M technologies are introduced and advantages of those technologies are explained.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.34-39
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• 2010

In order to achieve and maintain dimensional accuracy in laser micro-machining, dominant parameters such as laser power and laser focus position need to be monitored and controlled real time. Also, in order to selectively machine multi-layered materials, the material being presently machined need to be recognized. This paper presents an auto-focusing (AF) module to keep laser focus on a large-area surface; a real-time laser power stabilizing module based on optical attenuation; and a laser-induced breakdown spectroscopy (LIBS) module. With these monitoring modules, position error in laser focus on a 4" silicon wafer was kept below $4{\mu}m$, initially $51{\mu}m$, and laser power stability of a UV laser source was improved from 1.6% to 0.3%. Also, the material transition from polyimide to copper in machining of FCCL (flexible copper clad laminate) was successfully observed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.2 s.119
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• pp.105-113
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• 2007

In this study, three-dimensional rotordynamic analyses have been conducted using equivalent beam, hybrid and full three-dimensional models. The present computational method is based on the general finite element method with rotating gyroscopic effects of the rotor system. General purpose commercial finite element code, SAMCEF which includes practical rotordynamics module with various types of rotor analysis tools and bearing elements is applied. For the purpose of numerical verification, comparison study for a benchmark rotor model with support bearings is performed first. Detailed finite element models based on three different modeling concepts are constructed and then computational analyses are conducted for the realistic and complex three-dimensional rotor system. The results for rotor stability and mass unbalance response are presented and compared with the experimental vibration test data conducted herein.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.591-598
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• 2020

The all revision of the Road Name Address Act, which contains the contents to be used by expanding the road name address as a means of indicationg the location, has been resloved by the National Assembly. Addresses will be assigned to large-sized facilities (3D mixed-use complex spaces). Here, the 3D (Three-dimensional) address is assigned an indoor path section in the inner passage, dividing the section at intervals. The 3D address will be built on the address information map. For 3D address, data should be built and managed for a 3D complex space(indoor space). Therefore, in this study, the object of the 3D address is defined based on the address conceptual model defined in the international standard, and the 3D address data model is proposed based on IndoorGML. To this, it is proposed as a method of mapping the Core and Navigation module of IndoorGML so that the entity of the 3D address can be expressed in IndoorGML. This study has a limitation in designing a 3D address data model only, but it is meaningful that it suggested a standard for constructing 3D address data in the future.

• Journal of the Chungcheong Mathematical Society
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• v.8 no.1
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• pp.173-181
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• 1995

Let H and G be finite dimensional semisimple Hopf algebras and let A and B be left H and G-module algebras respectively. We use smash product algebras to show that 1) if A is right Artinian then $A^H$ is right Artinian, 2) $Soc\;V_A{\subset}Soc\;V_{A^H}$ and rad $V_A{\supset}\;radV_{A^H}$, 3) $K\;dim\;_BV_A=K\;dim\;_{B^G}V_{A^H}$.