• Journal of the Korean Ceramic Society
• /
• v.31 no.8
• /
• pp.927-933
• /
• 1994

Alumina composite membranes were prepared by chemical vapor deposition (CVD) using aluminum-tri-isopropoxide as a precursor. Porous alumina supports were used in deposition, which were in disk shape with mean pore diameter of 0.1 ${\mu}{\textrm}{m}$ and prepared by slip-coasting process. film deposition morphology on porous support was simulated through depositing alumina film on polycrystalline silicon pattern, and its step coverage observed by SEM showed one deviated from uniform step coverage. N2 permeability through composite membranes and the pressure dependence decreased as the deposition time increased. Initially, the N2 permeability of the top layer was tend to decrease rapidly, and then the degree of decrease in N2 permeability was tend to diminish with deposition time. The N2 permeability increased with heat treatment temperature and the crack was generated in top layer at 100$0^{\circ}C$.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.55-60
• /
• 2004

This study is concerned to the perforation phenomena of the oblique dual-plate by projectile. Experiment and simulation related to that was carried out. the variables considered in this phenomena include the electrolytic zinc coated steel sheet and carbon steel rod. In the former, the confirmation and projectile velocity possible phenomena of real phenomena is done, the latter, the effect of parameter such as time-step and grid space length is analized by using the three-dimensional Lagrangian explicit time-integration finite element code, HEMP. this code use the eight node hexahedral elements and in this study, Von-Mises Criteria is used as the strength model, Mie-Gruneisen is as the Equation of State. the simulation was performed by contrast with the experiment. through the calibration of the parameter of lagrangian code, reasonable result was approached.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.04a
• /
• pp.64-69
• /
• 2004

The work presented here deals with controller design using error model constructed with proportional control ramp response. The design aims at the improvement of transient response, steady-state error reduction with stability preservation, generation of the consistent contour error through the proportional gain regulation of a mismatched system. The first step is to generate tracking-error curve with proportional control only and decide the added error signal shape on the error curve. The next is to construct a table for the steady-state loop gain with step input. The table is used for selecting the proportional gain. The effectiveness of the proposed controller is confirmed through the simulation and experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.8
• /
• pp.42-49
• /
• 2012

Grid-connected photovoltaic generator system requires high performance PCS(Power Conditioning System) according to the standard of 'Distributed Generation Grid-Connected Technology Standards'. This paper presents the MPPT control method which improves output efficiency through fast tracking to the maximum power point of PV and a reduced self-excited vibration. Secondly, in this paper DVR function was applied to PCS to compensate the voltage sag frequently happening for a power system. The proposed PCS control is analyzed and compared to conventional PCS operating characteristic, the various insolation and loads, and voltage sag condition through PSIM tool. It proves the utility.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.10a
• /
• pp.19-26
• /
• 2004

This study constructs the reduced system by two-level condensation scheme. This scheme consists of two steps. First step selects the candidate area for the primary degrees of freedom by energy estimation in element level. In the second step, the primary degrees of freedom are selected by the sequential elimination scheme. The efficiency and reliability of this scheme is shown through the prediction of eigenvalues of a few numerical examples. Time integration in the reduced system can save the computing time effectively. The well-constructed reduced system can present the accurate behavior of the structure under arbitrary dynamic loads so much as the global system. Through the numerical example, the efficiency and reliability of the proposed scheme will be demonstrated.

• The KSFM Journal of Fluid Machinery
• /
• v.3 no.3 s.8
• /
• pp.7-11
• /
• 2000

A numerical study based on the three-dimensional thin-layer Navier-Stokes solver is carried out to analyze the flowfield through a single stage transonic compressor. Explicit fout-step Runge-Kutta scheme with spatially variable time step and implicit residual smoothing is used. The governing equations we discretized with explcit finite difference method. Mired-out average method is used at the interface between rotor and stator. And, an artificial dissipation model is used to assure the stability of solution. The results with k-w turbulence model were compared to the results with Baldwin-Lomax model, and physical phenomena of transonic compressor are presented. The two turbulence models give the results that show reasonably good agreements with experimental data.

• Proceedings of the KIPE Conference
• /
• 1998.11a
• /
• pp.55-59
• /
• 1998

By this time, Diode Rectifier or SCR has been used to gain DC Voltage for Electrolysis Power. Generally DC Voltage is produced from rectifier shall be transformed before rectifier using step-down transformer to obtain adaptable DC Voltage, rectifier output. In the same way, rectifier using SCR shall obtain output voltage after step-down voltage through transformer and control of the SCR firing angle. Transformer shall be used for this two methods to adjust the voltage. But the size and weight of the transformer are increased in accordance with the increase of capacity, and the hardships are accompanied in workspace or transportation. Besides, only the value of input voltage is possible to be regulated, and the expectation of current control is almost impossible during Electrolysis. This study has conducted Design and Simulation to reduce the size and weight of transformer and to be enable voltage and current control of Electrolysis power through high-speed switching using Inverter, Electronics device.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.135-135
• /
• 2001

In recent years there have been increasing interests in real-time object tracking with image information. Since image information is affected by illumination, this paper presents the real-time object tracking method based on neural networks that have robust characteristics under various illuminations. This paper proposes three steps to track the object and the fast tracking method. In the first step the object color is extracted using neural networks. In the second step we detect the object feature information based on invariant moment. Finally the object is tracked through a shape recognition using neural networks. To achieve the fast tracking performance, we have a global search for entire image and then have tracking the object through local search when the object is recognized.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.4
• /
• pp.108-117
• /
• 2015

In this paper, as a previous step of software development, through an analysis step in the basic design process of the FPSO crane, ERD, which could help develop common understanding between its developer and the user, was introduced. From the flowchart of the design process, the overall work flow in its development was understood. Then, after the design process of the crane was divided into many entities, the attributes of each entity were defined and the relationships between the entities were established, followed by ERD creation through the use of IDEF1X notation. The results of the analysis can be readily understood even by users who lack of software knowledge, and then their change requirements can be immediately reflected in the developed system that requires modification.

• Journal of the Korean School Mathematics Society
• /
• v.2 no.1
• /
• pp.93-104
• /
• 1999

The subject of this study was the graph of relation of direct inverse proportion, linear function and quadratic function in the 1st, 2nd and 3rd grade of current middle school mathematics curriculum. GSP materials were developed to simplify the principle, trait and characteristics of graphs and make them easier to understand. The overall aim of the materials is to improve the effectiveness of teaching and learning through the utilization of enhanced students' practice. Additionally, the use of the GSP will be useful in the development of mere effective materials. The effectiveness of the GSP materials will be as followings. 1. The step by step approach of GSP materials through computer interaction will enhance students motivation and interest in mathematics. 2. By presenting the subject matter simply and in a variety of ways, difficult concepts can be understood without the use of complex mathematical calculation. 3. The GSP program is different from CAI and other software programs. It should be used only after learning how to input and output data.