• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.39-44
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• 2005

A broadband DC to 40 GHz 5-bit MMIC digital attenuator has been developed. The ultra broadband attenuator has been achieved by newly inserted the transmission lines in conventional Switched-T attenuator and the optimization of the transmission line parameters. Momentum was employed in design for an accurate performance prediction at high frequencies and Monte Carlo analysis was applied to verify performance stability against the MMIC process variation. The attenuator has been fabricated with 0.15 $\mu$m GaAs pHEMT process. This attenuator has 1 dB resolution and 23 dB dynamic range. High attenuation accuracy has been achieved over all attenuation range and full 40 GHz bandwidth with the reference state insertion loss of less than 6 dB at 20 GHz. The input and output return losses of the attenuator are better than 14 dB over all attenuation states and frequencies.

• The Korean Journal of Financial Studies
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• v.9 no.1
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• pp.221-244
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• 2003

This study is aimed to investigate the effects of foreign exchange rates on stock market returns. For the United States, the United Kingdom, Germany, Japan and Korea, the cross-correlation precedence of foreign exchange rate on stock market is found in the case of Germany and Korea. But that of stock market is not observed in any case. We performed three kinds of causality and exogeneity test of Granger test, Sims test and Geweke-Meese-Dent test. The analyses on the full period show the time-lag causal, exogeneous relation of foreign exchange rates with Granger, Sims and GMD test for Korea. The United Kingdom presents the significance with Granger and Sims test while Germany reveals the time-lag relation with Granger and GMD test. When we divide the period into two parts with the Louvre Accord, the first part give the less degree of time-lag relation. But in the second period the three kinds of causality and exogeneity test propose consistent time-lag relation with foreign exchange rates on stock markets for the United Kingdom and Korea with the three test methods. And Granger's test prove German foreign exchange market have a time-lag relation on stock market.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.86-91
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• 2012

A multi purpose environmental monitoring system has been developed as a commercially available standard using the techniques which are FBG(Fiber Bragg Grating), Hetero-core spliced fiber optic sensor and etc, for the purposes of monitoring large scaled structures and preserving natural environments. The monitoring system has been tested and evaluated in a possible outdoor condition in view of the full scaled operation at actual sites to be monitored. Additionally, the developed systems in the previous works conveniently provided us with various options of sensor modules intended for monitoring such physical quantities as displacement, distortion, pressure, binary states, and liquid adhesion. In this paper, we extend the previous results to a water leakage detection problem and develop a sensing system as a result. By the experimental study, it is verified that multi-point leakage detection is possible using single line optical fiber.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.101-107
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• 2007

In this paper, the pulse charger with mode consersion type is proposed that can reuse the waste lead battery. The pulse charger uses the switch mode of the forward convert method. The pulse charger maintain the constant voltage in state removing the lead battery and when it connected the pulse charger, it is converted the charge mode of the constant current immediately. It continues the rapid charge until the full state of the lead battery. After that the pulse charger is converted to the charge mode of constant voltage automatically, and then it continues the normal charge. The experiment results show that the effectiveness of pulse charger such as the good performance and the prolonged durability in lead battery according to capacity states.

• International Journal of Contents
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• v.9 no.1
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• pp.98-103
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• 2013

The study investigated USFK's crisis communication responding to the case of two Koran girls' death. The two girls were hit by an American tank accidently. The accident has resulted in anti-American demonstrations by a large number of South Korean. The current research attempted to see what problems USFK's crisis communication with Korean publics. Through analyzing USFK news release in Korea and Army News (ARNEWS) in America regarding the case, the study answered what crisis communication strategies USFK used and How the USFK responded to the crisis. The results showed that USFK used full apology strategy and its crisis response was immediate, but prior reputation of USFK seemed making USFK's effort fruitless.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.58-60
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• 2017

In the offshore crane system, the requirements on the operating safety are extremely high due to many external factors. This paper describes a model for studying the dynamic behavior of the offshore crane system. The obtained model allows to evaluate the fluctuations of the load arising from the elasticity of the rope. Especially, in this paper, the authors design control system in which just winch rotation angle and rope tension are used without load position information. The controller design based on input-output feedback linearization theory is presented which can handle the effect of the elasticity of the rope and track the load target trajectory input. Besides that, a full order observer is designed to estimate unknown states. Finally, By the experiment results, the effectiveness of proposed control method is evaluated and verified.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.393-395
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• 2005

This paper describes implicitly restarted Arnoldi method (IRAM), which is a technique for combining the implicitly shifted QR mechanism with a k-step Arnoldi factorization to obtain a truncated form of the implicitly shifted QR-iteration. IRAM avoids numerical difficulties and storage problems normally associated with Arnoldi. This paper deals with the basic algorithms of IRAM as an intial research phase for developing the full featured eigenvalue analysis program for large power system up to 30,000 states.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.881-885
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• 2014

Photophysics of 10-hydroxybenzo[h]quinoline (HBQ) has been in controversy, in particular, on the nature of the electronic states before and after the excited state intramolecular proton transfer (ESIPT), even though the dynamics and mechanism of the ESIPT have been well established. We report highly time resolved fluorescence spectra over the full emission frequency regions of the enol and keto isomers and the anisotropy in time domain to determine the accurate rates of the population decay, spectral relaxation and anisotropy decay of the keto isomer. We have shown that the ~300 fs component observed frequently in ESIPT dynamics arises from the $S_2{\rightarrow}S_1$ internal conversion in the reaction product keto isomer and that the ESIPT occurs from the enol isomer in $S_1$ state to the keto isomer in $S_2$ state.

• 전기의세계
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• v.30 no.12
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• pp.822-831
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• 1981

Many different schemes of the adaptive observer and controller have been developed for both continuous and discrete systems. In this paper we have presented a new scheme of the reduced order adaptive observer for the single input discrete linear time invariant plant. The output equation of the plant, is transformed into the bilinear form in terms of system parameters and the states of the state variable filters. Using the plant output equation the discrete implicit adaptive observer based on the similar philosophy to Nuyan and Carroll is derived and the parameter adaptation algorithm is derived based on the exponentially weighted least square method. The adaptive model following control system is also constructed according to the proposed observer scheme. The proposed observer and controller are rather than simple structure and have a fast adaptive algorithm, so it may be expected that the scheme is suitable to the practical application of control system design. The effectiveness of the algorithm and structure is illustrated by the computer simulation of a third order system. The simulation results show that the convergence speed is proportinal to the increasing of weighting factor alpha, and that the full order and reduced order observer have similar convergence characteristics.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.7
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• pp.565-571
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• 2005

We present a novel speed estimation of a Permanent Magnet Synchronous Motor(PMSM) based on Support Vector Regression(SVR). The proposed method can estimate wide speed range, including 0.33Hz with full load, accurately in the steady and transient states where motor parameters variations are known without parameter estimator. Moreover, the method does not need offline training previously but is trained on-line. The training starts with the PMSM operation simultaneously and estimates the speed in real time. The experimental results shows the validity and the usefulness of the proposed algorithm for the 0.4Kw PMSM DSP(TMS320VC33) drive system.