• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.11
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• pp.891-895
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• 2010

Polymer dispersed liquid crystal (PDLC) films were prepared by the phase separation method using the liquid crystal (E7) and prepolymers. This work investigated the electro-optical characteristics of various PDLC films. In order to have good contrast ratio, the polymer refractive index must be adjusted to the ordinary refractive index of the liquid crystal. The driving voltage of PDLC films were mainly affected by elastic deformation. E7-Ebecryl810-IOA-TMPTA-HMPPO system had good threshold voltage and driving voltage and E7-Ebecryl810-EHA-PEGDA-HMPPO system had good contrast ratio.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.29-34
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• 2000

This paper describes a numerical study to make clear the characteristics of flow around a high speed catamaran hull advancing on calm water. The simulation is carried out at Froude number of 0.5 with a separation to length rations of 0.2 to 0.5. To simulate the flows, the Navier-Stokes solver is employed in which the free surface condition is included. Computations are performed in a rectangular grid system based grid system based on the Marker & Cell method. For the validation, the computation results are compared with the experiments.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.1
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• pp.11-18
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• 2003

We consider a single-input-single-output nonlinear system which is represented in a normal form. The model contains the uncertainty. A high-gain observer is used to estimate the states variables to reject a modeling uncertainty We design the globally bounded output feedback controller using sliding mode control to stabilize the closed-loop system. The globally bounded output feedback controller reduce the peaking in the states variables. The proposed method give a more design freedom in the design of the globally bounded controller than that of the previous work.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.848-851
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• 2003

In this paper, a separating system for used CRT recycling is presented. Depend on manufacturer CRTs has small differences in dimension for the same model, but the dimensions of the panel are nearly same. To simplifying configuration of the system, we developed CRT fixing pallets for every model of CRT. The height of cutting position for every model of CRT will be same. The cutting machine has two rotating arm and use metal-bond type diamond cutting wheel. Instead of water, two vortex tube type air-coolers are used for the cooling of cutter. Workers in recycling factory are generally old people. Therefore, control program should be easy to use and operate. Thus we developed GUI with very simple interface.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.181-184
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• 2002

CFD calculations are carried out to investigate the turbulent flow characteristics inside the duct of marine waterjet propulsors. The Reynolds-averaged Wavier-Stokes equations are solved using a finite-volume method. Standard $k-{\varepsilon}$ model and realizable $k-{\varepsilon}$ model are evaluated with an existing experimental data. Multi-block grid topology is adopted to describe the details of complex duct geometry. The present numerical methods are applied to the preliminary duct design of new waterjet propulsor system. Four different influx conditions are simulated to find out pressure and velocity distribution inside the intake duct. Attention is also paid upon the possible flow separation inside the waterjet duct. It is found that CFD tools can be used for the initial evaluation of inflow condition into the impeller of waterjet propulsor system.

• New & Renewable Energy
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• v.5 no.1
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• pp.40-46
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• 2009

Optimization of a rectangular profile annular fin with variable pipe inside radius is presented. This optimum procedure is based on fixed fin height and is made by using variables separation method. The optimum heat loss, corresponding optimum fin length and optimum fin efficiency are presented as a function of pipe inside radius, fin half height, inside fluid convection characteristic number and ambient convection characteristic number. One of results shows that the optimum fin length increases linearly with increase of pipe inside radius for fixed fin height and fin base radius.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.453-457
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• 2011

In this study, transonic aeroelastic response analyses haw been conducted for the business jet aircraft configuration considering shockwave and flow separation effects. The developed fluid-structure coupled analysis system is applied for aeroelastic computations combining computational structural dynamics(CSD), finite element method(FEM) and computational fluid dynamics(CFD) in the time domain. It can give very accurate and useful engineering data on the structural dynamic design of advanced flight vehicles. For the nonlinear unsteady aerodynamics in high transonic flow region, Navier-Stokes equations using the structured grid system have been applied to wing-body configurations. In transonic flight region, the characteristics of static and dynamic aeroelastic responses have been investigated for a typical wing-body configuration model. Also, it is typically shown that the current computation approach can yield realistic and practical results for aircraft design and test engineers.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.103-106
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• 2002

A gradient LC/MS system was constructed and applied for separation of biological samples. For example, a rapid and simple analytical method without pretreatment based on gradient ${\mu}LC/MS$ with a disposable microcolumn has been developed to determine B group vitamins in urine. Urine samples were directly injected to the disposable home-made microcolumn. The microcolumn can be emptied after being used for a series of urine samples, and repacked with fresh stationary phase. An overdose of vitamin pills were swallowed by healthy volunteers and the urine samples were taken 1,2,3,5, and 8 hours after swallowing. Vitamins immediately showed up in urine, hit the maximum, and disappeared swiftly. This technique is expected to have some application for clinical purposes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.299-299
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• 2011

In this study, transonic aeroelastic response analyses have been conducted for the business jet aircraft configuration considering shockwave and flow separation effects. The developed fluid-structure coupled analysis system is applied for aeroelastic computations combining computational structural dynamics(CSD), finite element method(FEM) and computational fluid dynamics(CFD) in the time domain. It can give very accurate and useful engineering data on the structural dynamic design of advanced flight vehicles. For the nonlinear unsteady aerodynamics in high transonic flow region, Navier-Stokes equations using the structured grid system have been applied to wing-body configurations. In transonic flight region, the characteristics of static and dynamic aeroelastic responses have been investigated for a typical wing-body configuration model. Also, it is typically shown that the current computation approach can yield realistic and practical results for aircraft design and test engineers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.475-481
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• 1999

This paper presents a recursive least square estimation algorithm to estimate parameters of the vector controlled induction machine based on measurements of the stator voltage, curents and slip frequency. Due to its recursive structure, this algorithm has the potential to be used for on-line estimation and adaptive control. The algorithm is designed using regression model derived from the motor electrical equation. This model is valid when there is a tittle-scale separation between vector control system and adaptive system. Vector control performed at fast stage and slow stage is in charge of parameters estimation. The performance of tile algorithm is illustrated by means of simulation results and experiment.