• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.837-844
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• 2017

The weir to regulate water level in a tide generation tank is above and below carried by two electric cylinders which are mounted on right and left of weir itself. In this case, a movement difference between right and left cylinder causes unbalance of weir and friction between weir and guide. And then, the weir will not be sent to target point. In this study, a synchronous control system is developed to take accurate and quick equilibrium of the weir. The control system based on cross coupled structure consists of two I-PD controllers and a lead compensator. Each of the I-PD controllers is designed in order that the electric cylinder may exactly follow the reference signal without overshoot and input saturation. And the lead compensator is designed to achieve stable and accurate synchronization. Finally, the simulation result shows that the designed synchronous control system is effective for elimination of synchronous error.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.962-968
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• 2011

The conventional lossless compression of color images is to apply a compression method to each of color components separately, without considering the channel correlation. There had been several methods that consider the channel correlation, but they were confined to the compression of satellite or aerial images only, and the performance of these algorithms to general photos is not satisfactory. This paper proposes a new lossless color image compression method that exploits the correlation between the color components. Specifically, asymmetric sampling is applied to transform an image into mosaic image and the rest, which are compressed separately. By using the information from the compressed mosaic image, the rest images are predicted for further reducing the information to be compressed. Experimental results show that the proposed method improves the compression performance by 35% over the conventional separate compression methods and 10% over the existing methods that exploit the channel correlation.

• Tunnel and Underground Space
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• v.10 no.2
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• pp.173-179
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• 2000

The influence of the plastic flow rules on the elasto-plastic behaviour of a discrete joint element was investigated by performing the numerical direct shear tests under both constant normal displacement and normal displacement conditions. The finite interface elements obeying Plesha’s joint constitutive law was used to allow the relative motion of the rock blocks on the joint surface. Realistic results were obtained in the tests adopting the non-associated flow rule, while the associated flow rule overestimated the joint dilation. To overcome the computational drawbacks coming from the non-symmetric element stiffness matrix in the conventional non-associated plasticity, the symmetric formulation of the tangential stiffness matrix for a non-associated joint element was proposed. The symmetric elasto-plastic matrix it derived by assuming an imaginary equivalent joint with associated flow rule which shows the same plastic response as that of original Joint with non-associated flow rule. The validity of the formulation was confirmed through the numerical direct shear tests under constant normal stress condition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.778-781
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• 2003

투어멀린(Tourmaline)은 비대칭 쌍극자를 가진 유극성 결정체로 광물 중에서 영구적으로 전기분극의 특성을 띄고 있는 유일한 물질로써 일명 "전기석"이라고 알려져 있고, 자체의 미약전류(약 0,06mA)와 함께 음이온 및 원적외선의 발생으로 최근 들어 우리 주변에서 건강과 환경을 위한 관심고조의 대상인 육방정계의 압전성 및 초전성을 띄는 붕규산염(주요성분: Mg, Fe, B, Si, Ca)으로, 원석(면역지수 ~1000)에 비해 수백 배의 효력이 있는 투어말린 세라믹(면역지수 ~418,000)을 비롯하여 이것을 이용한 새로운 아이디어 신상품들이 계속 개발되고 있다. 뿐만 아니라, 물분자를 만나면 수소(H$^{+}$)와 수산기(OH$^{-}$)로 전기분해하여 친수기와 소수기 부분으로 구분하며, H$^{+}$와 OH$^{-}$는 각각 $H_2O$와 결합하여 활성이 강한 hydronium ion(H$_3$O$^{+}$ 과 계면활성 작용이 있는 hydroxyl ion(H$_3$O$_2$$^{-}$)을 생성하며, 물속에서 계속 불안정한 상태로 존재하는 수산기는 hydroxyl (-)ion을 형성하여 약 알카리성(pH~7.4)을 띄고 물의 클러스터 세분화와 미네랄을 공급해 줌으로 체내에 들어오면 살균, 항균능력이 있는 면역기능을 갖게 되며, 혈액을 정화하고 자율신경을 자극하여 교감신경의 흥분을 억제한. 이와 함께 전기분극을 띈 투어멀린 입자는 다른 물질에 비하여 경이적 수치의 원적외선을 발생하여 강력한 열 효과와 높은 침투력으로 인체의 혈액순환 촉진과 혈전용해 작용으로 건강과 활력에 도움을 주는 것으로 확인되어 많은 관심을 끌고 있다. 따라서 유익한 이용가치를 인정받고 있는 투어멀린을 유용한 타 물질과 혼합물을 구성하여 성형 또는 EPD 전착하여 소결한 뒤, 소결체의 특성을 분석하여 그 응용성을 개발, 확보하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.35-41
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• 2004

In computational study on RF(Radio Frequency) plasmas, a 1D fluid models with an advantage of a short computational time are often adopted. However, in order to obtain realistic calculation results under a typical chamber geometry with unequal-sized electrodes, modeling of the plasma space is an issue to be investigated. In this paper, it is focused on that how much a 1D model can approximate a 2D model. 1D fluid models with unequal-sized electrodes, which have spherical and frustum geometry systems, were developed and their results were compared with those of 2D model with Gaseous Electronic Conference cell structure. Behavior of $N_2$ RF plasmas has been simulated using 1D and 2D fluid models and a technique to take account of unequal-sized electrodes in a 1D fluid models has been examined. Features of the plasma density and the electric potential were discussed as characteristic quantities representing the asymmetry of the chamber geometry.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.5
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• pp.401-406
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• 2008

Recently, portable magnetic sensors with high sensitivity are strongly required for various applications such as biosensor, nondestructive testing and directional sensor. A novel magnetic sensor system was developed by utilizing giant magnetoimpedance(MI) effect of soft magnetic ribbons. The sensor system consists of sensing head of $Co_{66}Fe_{4}Si_{15}B_{15}$ ribbon having asymmetric MI characteristics through exchange coupling produced by field-annealing in open air and circuit for signal processing. The sensor system showed almost linear characteristics in dynamic range of $-1\;Oe\;{\sim}\;1\;Oe$ and sensitivity of 10.5 V/Oe. The sensor was applicable to nondestructive testing system to detect defects in wire ropes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.825-834
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• 2008

Nose chine shape optimization study has been performed to maximize the directional stability at high angle of attack supersonic flow. Various chine shapes are generated using super ellipse equation. By numerically investigating the directional stability characteristics of those shapes, the baseline configuration for the shape optimization has been selected using the three-dimensional Navier-Stokes equations. The configuration is represented by the NURBS curves which can adjust the surface geometry by the control points. The response surfaces are constructed to obtain optimum shape which has high directional stability characteristics and lift-to-drag ratio. From this study, an efficient configuration design and optimization process which utilizes the parameter-based configuration generation techniques and approximation method has been established, then 29% improvement of the directional stability by strong vortexes from chine nose is accomplished.

• Journal of Broadcast Engineering
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• v.19 no.4
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• pp.478-490
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• 2014

In order to make 3-D display technique a better tool to provide viewers with realistic stereoscopic experience, various researches have been done in the many relevant fields. This psychophysical study was designed to investigate whether there was any difference in the perceptual processing between a dominant and non-dominant eye when a 3-D cue was provided exclusively to only one eye. We measured the reaction time for detecting a depth change by providing the viewer's each eyes with differential 3-D stimuli, which have systematical patterns. We obtained that there was a consistent 3-D perceptual performance when the 3-D cue was provided to the viewers' left eye regardless of their eye dominance. The result suggests that it might be a better technique to arrange the camera for left eye to carry 3-D cues to get the viewer's consistent 3-D perception.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2199-2205
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• 2017

The development of modern ICT technology constitutes cyber world by using infrastructure in country and society. There is no border in cyber world. Countries around the world are carrying out cyber attacks for their own benefit. A cyber killer strategy is needed to defend cyber attacks. In order to defend the cyber attack or to determine the responsibility of attack, it is important to grasp the attacker origin point. Strategic cyber kill chains are needed to strike against the attacker origin. In this paper, we study the analysis of attacker origin. And analyze the cyber kill chain for attacker origin point strike. Study the efficient and customized cyber kill chain strategy for attacking the origin point. The cyber kill chain strategy will be a practical strategy to replace the power of nuclear and missiles with asymmetric power.

• Korean Journal of Optics and Photonics
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• v.21 no.6
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• pp.235-240
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• 2010

We fabricate highly birefringent photonic crystal fiber with new structure using a stack and draw method. Fabricated fiber has two big air holes, one at each side of the outside air cladding region, leading to core ellipticity during the drawing process. Birefringence of the fabricated Hi-Bi PCF is measured to be $2.29{\times}10^{-4}$ (at 1550 nm).