• Journal of the Korean earth science society
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• v.39 no.4
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• pp.305-316
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• 2018

Satellite-derived sea surface winds (SSWs) and atmospheric motion vectors (AMVs) over the global ocean, particularly including the areas in and around tropical cyclones (TCs), have been provided in a real-time and continuous manner. More and better information is now derived from technologically improved multiple satellite missions and wind retrieving techniques. The status and prospects of key SSW products retrieved from scatterometers, passive microwave radiometers, synthetic aperture radar, and altimeters as well as AMVs derived by tracking features from multiple geostationary satellites are reviewed here. The quality and error characteristics, limitations, and challenges of satellite wind observations described in the literature, which need to be carefully considered to apply the observations for both operational and scientific uses, i.e., assimilation in numerical weather forecasting, are also described. Additionally, on-going efforts toward merging them, particularly for monitoring three-dimensional TC wind fields in a real-time and continuous manner and for providing global profiles of high-quality wind observations with the new mission are introduced. Future research is recommended to develop plans for providing more and better SSW and AMV products in a real-time and continuous manner from existing and new missions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.103-113
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• 2018

In this paper, an improved integral variable structure regulation controller is designed by using a special integral sliding surface and a disturbance observer for the improved regulation control of highly nonlinear rigid robot manipulators with prescribed output performance. The sliding surface having the integral state with a special initial condition is employed in this paper to exactly predetermine the ideal sliding trajectory from a given initial condition to the desired reference without any reaching phase. And a continuous sliding mode input using the disturbance observer is also introduced in order to effectively follow the predetermined sliding trajectory within the prescribed accuracy without large computation burden. The performance of the prescribed tracking accuracy to the predetermined sliding trajectory is clearly investigated in detail through the two theorems, together with the closed loop stability. The design of the proposed regulation controller is separated into the performance design and robustness design in each independent link. The usefulness of the algorithm has been demonstrated through simulation studies on the regulation control of a two-link robot under parameter uncertainties and payload variations.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.904-910
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• 2009

The development of effective cellular imaging requires a specific labeling method for targeting, tracking, and monitoring cellular/molecular events in the living organism. For this purpose, we studied the cellular uptake of isocyanide-functionalized silver and gold nanoparticles by surface-enhanced Raman scattering (SERS). Inside a single mammalian cell, we could monitor the intracellular behavior of such nanoparticles by measuring the SERS spectra. The NC stretching band appeared clearly at ${\sim}2,100cm^{-1}$ in the well-isolated spectral region from many organic constituents between 300 and 1,700 or 2,800 and $3,600cm^{-1}$. The SERS marker band at ${\sim}2,100cm^{-1}$ could be used to judge the location of the isocyanide-functionalized nanoparticles inside the cell without much spectral interference from other cellular constituents. Our results demonstrate that isocyanide-modified silver or gold nanoparticle-based SERS may have high potential for monitoring and imaging the biological processes at the single cell level.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.117-120
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• 1998

It is analyzed the erosing process of the polymeric insulator for outdoor use with the inclined plane method. Materials used are the different type of silicone rubber, they have the content of filler and component each other. As the content of filler added to improve the tracking and erosion resistance. It has the difference of electrical performance and erosion rate. The dry-band arc is also the parameter of accelerating erosion, and appear in the form of leakage current, and the activities of leakage current has a close relationship with the surface hydrophobicity. In this paper, the erosion growth is observed by measuring the time from the voltage application to the whole breakdown, and the erosion depth. In addition, it is measured the hydrophobicity and leakage current to be a cause of erosion by the erosion steps, studied SEM, EDX for observing the transformation of surface structure by erosing.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.5
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• pp.477-486
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• 2008

Numerical analysis for slamming impact phenomena has been carried out when 2-dimensional wedge shaped structure with finite deadrise angles enter the free surface by using a commertial CFD code, FLUENT. Fluid is assumed incompressible and entry speed of the structure is kept constant. Geo-reconstruct scheme (or PLIC-VOF scheme) is used for the tracking of the deforming free surface. User defined function of 6 degrees of freedom motion and moving dynamic mesh option are used for the expression of the downward motion of the structure and deforming of unstructured meshes adjacent to the structure. The magnitude and the location of impact pressure and the total drag force which is the summation of pressures distributed at the bottom of the structure are analyzed. Results of the analysis show good agreement with the results of similarity solution, asymptotic solution and the solution of BEM.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.154-162
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• 2002

The effect of nonlinear friction in the low velocity is dominant in precise controlled mechanisms and it is difficult to model. This paper is concerned with the compensation for friction using the variable structure system approach as nonmodel based method. The problem of chattering in the sliding mode controller is suppressed by the implementation of the boundary layer concept. And the estimation for friction using sliding mode observer makes the upper bound of matched uncertainty reduced. Accordingly, the effect of chattering can be more suppressed. And the sliding surface is constructed by adding an integral component to the switching function that is made by using error dynamics. This sliding surface guarantees the good tracking performance. Experimental results for a XY table system show that the proposed method has a good performance especially in the low velocity.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.389-396
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• 2008

The hybrid model can be used to predict the initial near field mixing and the far field transport of the buoyant jets, which are discharged from the submerged wastewater ocean outfall. In the near field, the jet integral model can be used for single port diffusers while the ${\sigma}$ transformed particle tracking model was used in the far field. In this study, the experimental study was performed to verify the developed hybrid model in the previous research. The developed hybrid model properly predict the surface and vertical concentration distribution of the single buoyant jets with various effluent and ambient conditions. The hybrid model can also simulate the surface concentration distribution of the rosette diffuser except for the parallel diffuser with the higher densimetric Froude number due to the assumption that dynamic effects of the effluent plumes are negligible in the far field. The application of the hybrid model to rosette diffusers can predict the concentration near the diffuser more accurately when the line-plume approximation is used.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1365-1372
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• 2001

In the planar flow casting(PFC) process, the conditions of the melt puddle between nozzle and rotating wheel affect significantly the quality and dimensional uniformity of the downstream ribbon. For stable puddle formation, the nozzle is placed very close to the quenching wheel, so the surface-tension and wall-adhesion forces have an important effect upon the fluid flow.\`In this study the planar flow casting process has been mode]ed using the VOF method for free surface tracking. The transient puddle formation from the present analysis shows good agreements with the previous experimental results. Furthermore, the variation of melt temperature and the corresponding cooling rate of the melt have been examined. The present results also show how the melt puddle can be farmed on the rotating substrate, how the melt flows within the puddle, and how the changes of the process variables affect the puddle formation and its corresponding fluid flow and heat transfer behavior.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.210-211
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• 2018

In general, the dam break problem is demonstrated to simulate open-channel disturbance due to large violent waves. These days, the large violent waves at shore and coastline can be seen frequently such like tsunami. The conventional computational fluid dynamics program based on Grid system, can be used to simulate this problem with large deformation of free surface in the restricted condition due to its limitation. The particle method based on fully Lagrangian approach is able to simulate large deformation of free surface by tracking each particles. In this study, the simulation of disturbance of mobile-bed due to large violent waves was investigated by using particle method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.314-324
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• 2020

Due to the nonlinearity and environmental uncertainties, the design of the ship's steering controller is a long-term challenge. The purpose of this study is to design an intelligent autopilot based on Extended Kalman Filter (EKF) trained Radial Basis Function Neural Network (RBFNN) control algorithm. The newly developed free running model scaled surface vessel was employed to execute the motion control experiments. After describing the design of the EKF trained RBFNN autopilot, the performances of the proposed control system were investigated by conducting experiments using the physical model on lake and simulations using the corresponding mathematical model. The results demonstrate that the developed control system is feasible to be used for the ship's motion control in the presences of environmental disturbances. Moreover, in comparison with the Back-Propagation (BP) neural networks and Proportional-Derivative (PD) based control methods, the EKF RBFNN based control method shows better performance regarding course keeping and trajectory tracking.