• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.601-609
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• 2002

In multi-path wireless channels with time-variant delay profile, a mobile station measures the received signal strength and report it to network which performs network control function such as handover. In order to improve the maximum ratio combining (MRC) gain, it also should search the strongest signal paths and measure their time offsets fast and exactly. This paper proposes some methods of fast and exactly measuring the multi-path signal strength and time offset. Since the W-CDMA system adopts antenna diversity technique for the next generation high speed packet access (HSDPA) service, we derive the optimum design parameter values for the proposed methods through computer simulations under the HSDPA conditions o( low speed of mobile, of no power control, and of multi-path wireless environment with transmit and receive antenna diversity. Finally, we prove the validity of the proposed methods by showing the improvement of the bit error rate (BER) performance.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.73-76
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• 2005

Preamble based synchronization result in performance degradation due to the high time variation in the power delay profile of the channel in fast varying channel. Since most of the timing metric that exploit the preamble is not based on theoretical back ground, it is not easy to find out the reason. In this paper, the behavior of the timing metric in the multipath fading channel is explained.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.91-100
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• 2007

Many manufacturing devices must execute motions as quickly as possible to achieve profitable high-volume production. Most of them have devices having flexibility and a time delay of one sampling is added to the plants when they are controlled by fast discrete controllers, which brings about non-minimum phase zeros. This paper develops a control strategy that combines feedforward and feedback control with command shaping for such devices. First, the feedback controller is designed to increase damping and eliminate steady-state error. Next, the feedforward controller is designed to speed up the transient response. Finally, an appropriate reference profile is generated using command-shaping techniques to ensure fast point-to-point motions with minimum residual vibration. The particular focus of the paper is to understand the interactions between these individual control components. The resulting control strategy is demonstrated on a model of a high-speed semiconductor manufacturing machine.

• East Asian mathematical journal
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• v.36 no.1
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• pp.81-90
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• 2020

Many compartment models assume a kinetically homogeneous amount of materials that have well-stirred compartments. However, based on observations from such processes, they have been heuristically fitted by exponential or gamma distributions even though biological media are inhomogeneous in real environments. Fractional differential equations using a specific kernel in Pharmacokinetic/Pharmacodynamic (PKPD) model are recently introduced to account for abnormal drug disposition. We discuss a tumor growth inhibition (TGI) model using fractional-order derivative from it. This represents a tumor growth delay by cytotoxic agents and additionally show variations in the equilibrium points by the change of fractional order. The result indicates that the equilibrium depends on the tumor size as well as a change of the fractional order. We find that the smaller the fractional order, the smaller the equilibrium value. However, a difference of them is the number of concavities and this indicates that TGI over time profile for fitting or prediction should be determined properly either fractional order or tumor sizes according to the number of concavities shown in experimental data.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.323-327
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• 1995

A new air knife system for coating thickness control in hot dip galvanizing process had been developed and installed on the CGL in Pohang Steel Works, POSCO. This new system consists of air knives with remotely adjustable nozzle slot and an automatic control system which can control both longitudinal and traverse coating deviations. Based on the optimal control algorithm, a traverse coating deviation control was designed. The controller controls the lip profile of the air knives with flexible structure according to the deviation of coating weight. From the measured values which are dependent on the strip width, the lip gaps are calculated with optimal algorithm and the model of the coating deviation. Time delay between knives and a coating thickness gauge is solved by the Smith Predictor.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.109-109
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• 2010

최근 AC-PDP에서 MgO Protective Layer 위에 별도의 기능막(Functional Layer)을 사용하고 있는데, 이 기능막인 MgO 나노 입자는 장시간 구동시 AC_PDP panel내에서 plasma 방전에 의하여 MgO Protective Layer와 기능막이 방전 공간에 형성 된 이온에 의해 Sputtering 또는 재 증착 될 수 있다. 본 실험에서는 조성이 다른 기능막이 적용된 AC-PDP Test panel을 제작하여 장시간 구동 후 기능막인 두 가지 다른 MgO 나노 입자의 재형성된 형태를 주사 전자 현미경(Scanning Electron Microscope)을 통해 Surface Profile 및 구조의 변화를 분석하고, 또한 음극선 분광 분석(Cathodoluminascence)을 통하여 방전 영역과 비방전 영역의 delay time, 방전전압 및 효율 등의 전기 광학적 특성과의 관계를 분석하고자 한다.

• Journal of Applied Reliability
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• v.17 no.2
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• pp.150-158
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• 2017

Purpose: The RAM objective is a very important factor that has a great effect on the improvement of the operation ration during the operation maintenance and the reduction of the life cycle cost. It is used as a design criterion during the system development, and its sufficiency should be evaluated during its test evaluation. Method: This study analyzed the cases related to RAM objective setting and suggested the improvement measures. Result: The base data for RAM objective is OMS/MP, which needs to be drawn up under the supervision of the requirement military, and a high-accuracy operating availability should be set through ALDT calculation which reflects the military logistics support environment. In addition, data collection necessary for RAM objective and RAM analysis should be made by supplementing the input data of DELIIS. Conclusion: This study suggests improvement of RAM objective considering for the weapon system.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.419-419
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• 2010

최근 AC-PDP의 효율향상을 위해 MgO Protective Layer 위에 별도의 기능막(Functional Layer)을 적용하고 있으며 기능막의 재료로는 MgO 나노 입자를 사용하고 있다. 그러나 장시간 구동시 AC-PDP Panel 내에서 Plasma 방전에 의하여 MgO Protective Layer와 기능막이 방전 공간에 형성 된 이온에 의해 Sputtering 또는 재 증착 될 수 있다. 본 실험에서는 기능막이 적용된 AC-PDP Test Panel을 제작하여 장시간 구동 후 MgO Protective Layer와 기능막인 MgO 나노 입자의 재형성된 형태를 주사 전자 현미경(Scanning Electron Microscope)을 통해 Surface Profile 및 구조의 변화를 분석하고, 또한 음극선 분광 분석(Cathodoluminascence)을 통하여 방전 영역과 비방전 영역의 delay time, 방전전압 및 효율 등의 전기 광학적 특성과의 관계를 분석하고자 한다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.107.1-107.1
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• 2014

We have developed and commercialize a time-of-flight - medium energy ion scattering spectrometry (TOF-MEIS) system (model MEIS-K120). MEIS-K120 adapted a large solid acceptance angle detector that results in high collection efficiency, minimized ion beam damage while maintaining a similar energy resolution. In addition, TOF analyzer regards neutrals same to ions which removes the ion neutralization problems in absolute quantitative analysis. A TOF-MEIS system achieves $7{\times}10^{-3}$ energy resolution by utilizing a pulsed ion beam with a pulse width 350 ps and a TOF delay-line-detector with a time resolution of about 85 ps. TOF-MEIS spectra were obtained using 100 keV $He^+$ ions with an ion beam diameter of $10{\mu}m$ with ion dose $1{\times}10^{16}$ in ordinary experimental condition. Among TOF-MEIS applications, we report the quantitative compositional profiling of 3~5 nm CdSe/ZnS QDs, As depth profile and substitutional As ratio of As implanted/annealed Si, Ionic Critical Dimension (CD) for FinFET, Direct Recoil (DR) analysis of hydrogen in diamond like carbon (DLC) and InxGayZnzOn on glass substrate.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.9-21
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• 2016

Nowadays various methods for energy saving have been studied in IP networks. This paper suggests a 2-phase OSPF routing method for energy saving on IP networks having various energy profiles and analyzes its characteristics. The phase-1 of the routing is an OSPF routing method considering the energy cost of devices besides existing metrics to minimize energy consumption. In the phase-2 of the routing, it makes core nodes go into sleep sate for energy saving and reroutes the paths affected by sleeping core nodes. At this time, we confirm that the characteristics of mean delay and energy efficiency can be satisfied by limiting an allowable hop number in the reroute paths, and utilization rate of nodes and links for assuring energy saving and network-level QoS. Since the efficiency of energy saving and delay characteristics differ according to selection methods of core nodes to go into sleep state, it is that the a method of core node selection based on MP(minimum_path) is more excellent than others in terms of network-level QoS and energy saving in IP networks.