• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.2
• /
• pp.224-227
• /
• 2006

We have chained 459nm blue laser radiation generated by intracavity sum frequency generation( SFG ) due to the mixing of the 1064 nm laser output of a Nd:YVO4 pumped by diode and the 809nm radiation from higg-power semiconductor laser(500mW). The maximum blue output power of 0.95 mW was obtained using 400 mW input power of semiconductor laser at the type II phase matching condition (${\psi}=90^{\circ}\;{\theta}=90^{\circ}$). The threshold input power of blue laser generation was 120 mW.

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.873-876
• /
• 1993

A scheme of IEVSC(Integral Error Variable Structure Controller) is proposed for the DC servo systems with the disturbances which does not satisfy the matching condition. The structure of IEVSC is composed of state observer, VSC, and servo compensator which is designed for the output variable enhances the robustness against all type of disturbances. The performances of proposed IEVSC are verified through simulations for the DC servo motor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.593-599
• /
• 2005

This paper is concerned with the vibration analysis of a rectangular plate with a rectangular hole. Even though there have been many methods developed for the addressed problem, they suffer from computational time. In this paper, we developed a new methodology called Independent Coordinate Coupling Method which can couple two independent coordinate systems for the entire plate domain and the hole. By matching the deflection condition imposed on the expressions, the relationship between the global axes and the local axes is derived. This formula is then used for the calculation of the eigenvalue problem. The numerical results show the efficacy of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.666-669
• /
• 2004

Substructures position is considered as design parameter to obtain optimal structural changes to raise its dynamic characteristics. In conventional SDM (structural dynamics modification) method, the layout of modifying substructures position is first fixed and at that condition the structural optimization is performed by using the substructures size and/or material property as design parameters. But in this paper as a design variable substructures global translational and rotational position is treated. For effective structural modification the eigenvalue sensitivity with respect to that design parameter is derived based on measured frequency response function. The optimal structural modification is calculated by combining eigenvalue sensitivities and eigenvalue reanalysis technique iteratively. Numerical examples are presented to the case of beam stiffener optimization to raise the natural frequency of plate.

• Journal of the Korea Society of Computer and Information
• /
• v.7 no.3
• /
• pp.56-59
• /
• 2002

In this study, new serial and parallel resistor and capacitor-frequency-dependent negative resistance configurations are implemented that use one plus type four-terminal floating nullor(FTFN) and three passive components. The values of simulated elements can be orthogonally adjusted without any matching condition. High pass filter designed with this FTFN and AD844. Computer simulation was performed using the AD844 macro model by HSPICE. Simulated results agree well with theoretical values.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.11C no.4
• /
• pp.150-154
• /
• 2001

In this paper, we presented a novel structure of microstrip directional coupler for realizing the high directivity characteristic and tight coupling. The achievement of the high directivity with microstrip configuration was carried out by matching the even and odd mode effective phase velocities. By using 2-dimensional finite element (FE) calculations, the phase velocity for each mode and design parameters were extracted for given dimensions. Based on the extracted design parameter with phase-matched condition, we designed and fabricated 3dB and 4.7dB directional coupler at 2.0GHz. Experimental results of microstrip coupler show good performance with excellent isolation characteristics.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.151.5-151
• /
• 2001

Sliding mode control is investigated for a discrete-time system with uncertainties. The narrowest neighborhood of the sliding surface is shown in which the state can remain. The range is determined by the upper bound of the absolute value of the uncertainty and the equation of the sliding surface. A sliding mode control algorithm is proposed to keep the state there without requiring an enormous input. Under the presence of the system parameter variations, the origin is not always stable although the sliding surface represents the stable dynamics and the state is kept in this neighborhood. The condition for the origin to be stable is investigated. Furthermore, the problems occurring when a continuous-time sliding mode control being ...

• Ocean Systems Engineering
• /
• v.14 no.2
• /
• pp.115-139
• /
• 2024

In this study, numerical study of a long, straight, side-anchored floating bridge with discrete pontoons subjected to combined earthquakes and waves is conducted. Ground motions with magnitude corresponding to 200 YRP (years return period) earthquake in South Korea are generated based on the spectral matching method from a past earthquake record in California. Several sensitivity studies are carried out for bridge end condition, for different site classes (hard rock S1 and soft and deep soil S5), and for three different excitations (earthquake only, wave only, and earthquake-wave combined). Bridge and pontoon motions, bending moments along the bridge, and mooring tensions are systematically examined through coupled time-domain simulations by commercial program OrcaFlex. The numerical results show that the impact of earthquakes on floating bridges is still of importance especially for soft soil although ground motions are less directly applied to the structure than fixed bridges.

• Proceedings of the Korea Contents Association Conference
• /
• 2006.11a
• /
• pp.417-420
• /
• 2006

Recently we could generation of 3-D simulation image by use of various image contents, so I tried advanced methods very easily leads to the location on the GIS environments. Its used basically air photos and satellite sensor images for them. For the generate 3-D spatial be suitable to matching map coordinates using elevation data from digital topographic files, and matching to 3D spatial image contents through perspectives view condition composed to move according to fixed roads until arrive to location. Through this new system which tourists are able to simulate the interest paths or locations and to visit the cultural inheritance was proposed by combining various spatial data with the multimedia contents. This system provides people with guidance to locate the cultural assets in the Web environments. The developed system which is more convenient to provide tourists with the information and they are able to access automatically to location easily. In the future, the visitors are able to use easily the 3d image contents on the Internet or from the public tour information desk by using the simulation images.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.4 no.1
• /
• pp.11-19
• /
• 2008

Groundwater flow in confined aquifer and heat transport in underground geologic media are using same governing equation(line source) like well fuction. Therefore the conventional slope method using only later data obtained from in-situ thermal response test to determine the thermal conductivity of vertical geothermal heat exchanger(GHEX) is basically identical with one of Theis straight line method of aquifer test under artesian condition. In case that the pumping rate(Q, $m^3$/d) and drawdown(s,m) which are used for input data of existing hydrogeologic computer programs for aquifer test are replaced and converted to supplying heat energy per unit length of bore hole(Q/L,w/m or Kcal/h.m) and temperatures (T,$^{\circ}C$)measured at in and out-let of GHEX as in put data respectively, thermal conductivity around geothermal heat exchanger can be easily estimated without any special modification of the existing hydrogeologic computer program. Two numbers of time series temperature variation data obtained from in situ geothermal response test are analized using Theismethods(standard curve and straight line method) by using existing aquifer test program and conventional Slope method proposed by ASHRAE. The results show that thermal conductivity values estimated by two straight methods are identical and the difference of estimated values between standard curve methods and Slope method are also within acceptable ranges. In general,the thermal conductivity estimated from Theis straight linemethod gives more accurate value than the one of Slope method due to that Slope method uses only visual matching otherwise Theis method uses automatic curve matching estimation with reducing RSS.