• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.6
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• pp.577-590
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• 2021

In this paper, we theoretically analyzed the self-alignment/navigation performance in the accelerometer resonance state generated by dither motion of ring laser gyroscope in LINS and verified it through simulation. As a result of analysis, it is confirmed that the amplitude of the accelerometer measurement amplified in the accelerometer resonance state is decreased in the process of sampling per the navigation calculation period and that frequency is changed by the aliasing effect too. It was also analysed that the attitude error in self-alignment is determined by the amplitude/frequency of the accelerometer measurement, the gain of the self-alignment loop, and the velocity and position error in the navigation is determined by the amplitude/frequency/phase error of the accelerometer measurement. This analysis and simulation results show that the self-alignment and navigation performance is not be degraded only when the amplification factor of the accelerometer measurement in the accelerometer resonance state is 3 or less

• The Journal of Korean Physical Therapy
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• v.35 no.6
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• pp.213-219
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• 2023

Purpose: In this study, based on the error augmentation, we performed walking training with increased rhythmic auditory stimulation speed on the affected side (IRAS) and walking training with decreased rhythmic auditory stimulation speed on the unaffected side (DRAS). The purpose of this study was to verify whether motor learning was effective in improving balance ability. Methods: Twenty-eight subjects with chronic stroke were recruited from a rehabilitation center. The subjects were divided into three groups: an IRAS group (10 subjects), a DRAS group (9 subjects), and control group (9 subjects). They received 30minutes of neuro-developmental therapy and walking training for 30minutes, five times a week for three weeks. Static and functional balance ability were measured before and after the training period. Static balance was measured by balancia software. Functional balance was measured by the timed up and go test (TUG) and the berg balance scale (BBS). Results: After the training periods, the IRAS group showed a significant improvement in TUG, BBS, area 95% COP, and weight distribution on the affected side when compared to both the DRAS group and control group (p<0.05). Conclusion: Based on the results of this study, it is possible to consider error augmentation methods of motor learning if rhythmic auditory stimulation is applied to stroke patients in clinical practice. If the affected side is shorter than the unaffected side, the affected side should be adjusted to the increased rhythmic auditory stimulation speed, which is considered to be an effective intervention to improve balance ability.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.106-108
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• 2006

본 논문에서는 오버레이 네트워크 환경에서 비디오 스트리밍 서비스의 성능을 향상시키기 위한 수직 핸드오버 메커니즘을 제안한다. 본 논문에서는 error propagation 문제를 완화함으로써 비디오 스트리밍 서비스의 성능을 향상시킨다. 이를 위해 프레임들의 전송 경로를 유형별로 분리하고, 프레임들의 손실률을 최소화하는 재전송 정책을 사용하며, forced 수직 핸드오버 시 멀티캐스팅 방법을 사용하였다. 또한 stability period 정의하여 핑퐁 현상이 전송성능에 미치는 영향을 줄였다. 시뮬레이션을 통해 제안하는 방안이 error propagation 문제를 개선함으로써 이동 사용자에게 끊김없는 비디오 스트리밍 서비스를 제공함을 알 수 있었다.

• Journal of the Korea Society of Computer and Information
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• v.21 no.5
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• pp.65-71
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• 2016

Bluetooth technology(BT) is a standard for short distance wireless communication and widely used to connect and control various electronic and telecommunication devices without wires, where CSR8670 chip is generally adopted. These BT devices are required to comply with BT specification and the equipments for conformance test are also important. However, the existing BT testing methods have inconvenience in that they are mostly time-consuming procedure due to not only repetitive execution for each evaluation element but also error-prone nature of manual experiments. This paper proposes an automated BT communication test method using CSR8670 chip, which solves the problems related to manual testing methods. The proposed method can reduce the development period of BT products and guarantee the quality improvement owing to the exact system error detection capability.

• Journal of Labour Economics
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• v.21 no.2
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• pp.17-46
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• 1998

In this paper, I pursue an empirical analysis of different patterns of employment and wage adjustments to demand changes for the US and Japan. Analyzed are the data in the 70's and 80's, the period that the two countries are believed to show most conspicuous diverging patterns. Using the framework of cointegration and error correction, I establish that in the US it is employment level, while in Japan it is wages, that is more responsive to output fluctuations both in the long run and the short run. All the comparisons on the long run relationships are estimated and tested based on the system cointegrating regressions, and the transition from the short run to the long run responses are investigated using impulse response analysis of the error correction models. I also study differences across genders and establishment sizes within each country. For males and females in Japan, the adjustments are significantly different both in the long run and the short run, but for the firms of different sizes they diverge only in the short run. In contrast to some of the earlier work, the gender effect turns out to be insignificant in the US.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.5
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• pp.599-606
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• 2018

Failure data of systems in many field can be erroneous, which influences the reliability analysis of the systems. The general form of failure data is right censored data with accurate time information. But due to its nature of data collection in the military field, failure time of one-shot weapon systems can have errors which are related to the maintenance period. So this paper suggests a model that can reduce the error by utilizing interval censored data as an alternative to right censored data in weibull distribution.

• International Commerce and Information Review
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• v.8 no.2
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• pp.299-312
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• 2006

This study examines the relations among wage differentials, trade, and productivity in Korea, using the methodology of Granger causality and vector error correction modelling. Cointegration test results over the 1975-2004 period indicate that all the test variables are cointegrated. Therefore, wage differentials, trade, and productivity are all related in the long run. We found some evidence on long-run relationship, while there is no short-run relationship between three test variables. First, trade and wage differentials have positively and bi-directionally Granger causality in the long-run. Second, productivity Granger causes negatively wage differentials in the long-run. Finally, productivity Granger causes positively trade in the long-run. These results explain partially the current theoretical predictions for wage inequality as well as supports the productivity-led growth hypothesis in the Korean economy.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.620-623
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• 2000

A very simple control approach using neural network for the robust position control of a Permanent Magnet Synchronous Motor(PMSM) is presented The linear quadratic controller plus feedforward neural network is employed to obtain the robust PMSM system approximately linearized using field-orientation method for an AC servo. The neural network is trained in on-line phases and this neural network is composed by a fedforward recall and error back-propagation training. Since the total number of nodes are only eight this system can be easily realized by the general microprocessor. During the normal operation the input-output response is sampled and the weighting value is trained multi-times by error back-propagation method at each sample period to accommodate the possible variations in the parameters or load torque. And the state space analysis is performed to obtain the state feedback gains systematically. IN addition the robustness is also obtained without affecting overall system response. This method is realized by a floating-point Digital Singal Processor DS1102 Board (TMS320C31) The basic DSP software is used to write C program which is compiled by using ANSI-C style function prototypes.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.4
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• pp.94-100
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• 2002

The conventional sliding mode control (SMC) technique requires a priori knowledge of the upperbounds of disturbances and/or modeling uncertainties to assure robustness. This, however, may not be easy to obtain in practical situation. This paper presents a new methodology, a sliding mode control with disturbance estimator (SMCDE), which offers a robust control performance without a priori knowledge about the disturbance. The proposed technique is featured by an average value of the imposed disturbance over a certain period. A nonlinear spring-mass-damper system and a two-link robot system are adopted as illustrative application examples. Control performances such as estimation error and tracking error are compared between the proposed methodology and conventional scheme.

• Journal of Astronomy and Space Sciences
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• v.20 no.2
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• pp.101-108
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• 2003

This study reports one approach for the classification of magnetic storms into recurrent patterns. A storm event is defined as a local minimum of Dst index. The analysis of Dst index for the period of year 1957 through year 2000 has demonstrated that a large portion of the storm events can be classified into a set of recurrent patterns. In our approach, the classification is performed by seeking a categorization that minimizes thermodynamic free energy which is defined as the sum of classification errors and entropy. The error is calculated as the squared sum of the value differences between events. The classification depends on the noise parameter T that represents the strength of the intrinsic error in the observation and classification process. The classification results would be applicable in space weather forecasting.