• MALSORI
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• no.52
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• pp.61-84
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• 2004

This study investigates the Korean native speakers' English liquid perception and production. Perception and production experiments were each conducted twice before and after a short period of explicit learning process of phonetic characteristics of English liquids. The results showed that correlation between perception and production varied depending on factors. In both perception and production, word-final position was the most difficult, and cluster position was the easiest. A considerable improvement was observed in word-initial and medial positions in production, whereas no improvement was achieved in word-final position, especially in production. This study is also concerned with the formant structures of Korean native speakers' production of English liquids in order to see what acoustic features are highly correlated with Korean native speakers' production accuracy of English liquids. The results showed that F2 did not show a high correlation while F3 was a strong correlate of the production accuracy.

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.357-362
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• 2015

We examine the principle of a modified Pound-Drever-Hall (PDH) technique to measure the free spectral range of a Fabry-Perot etalon (FPE). The FPE's periodic transmission of phase-modulated light allows us to adopt a sampling theorem to develop a new relationship for the PDH error signal. This leads us to find the key parameters governing the measurement accuracy: the phase modulation index ${\beta}$ and the FPE finesse. Without any additional complexity for background noise reduction, we achieve a measurement accuracy of 0.5 ppm. The improvement is mainly attributed to the wide-band phase modulation approaching ${\beta}=10$, and partly to the use of both reflected and transmitted light from the FPE and good FPE finesse.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.5
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• pp.102-108
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• 1996

Adaptive resonance theory (ART2) characterized by its built-in mechanism of handling the stability-plasticity switching and by the adaptive learning without forgetting informations learned in the past, is based on an unsupervised template matching. We propose an improved tow-stage learning algorithm for aRT2: the original unsupervised learning followed by a new supervised learning. Each of the output nodes, after the unsupervised learning, is labeled according to the category informations to reinforce the template pattern associated with the target output node belonging to the same category some dominant classes from exhausting a finite number of template patterns in ART2 inefficiently. Experimental results on a set of 2545 FLIR images show that the ART2 trained by the two-stage learning algorithm yields better accuracy than the original ART2, regardless of th esize of the network and the methods of evaluating the accuracy. This improvement shows the effectiveness of the two-stage learning process.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1040-1043
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• 1996

The accuracy of the servo control in CNC system has a great influence on the duality of machine product. Tracking performance of the servo control is deteriorated mainly by the time delay of the servo system and the inertia of the work table or bed. Contouring errors occur in every interpolation steps by the effect of the tracking performance. In this paper, $H_{\infty}$ two-degree-of-freedom(TDF) controller is designed for improvement to improve the tracking performance. The designed controller is applied 3-axis machining center model and the cutting accuracy is simulated in case of corner cutting, circular and involute interpolation. Simulation results show that $H_{\infty}$ TDF controller designed in this paper has a good effect to improve tracking performance in CNC system.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1021-1026
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• 1990

Accuracy improvement of a self-mixing semiconductor laser range finder is predicted by simulation, in which the laser modulation current is reshaped to give an ideal triangular waveform of the optical frequency change. The maximum range measurement error of less than 0.1% in a wide range of O.1m to 1m is expected by the reshaping of the modulation current. Experimental verification of the effect of current reshaping on the linearization of the derivative of the optical frequency change curve is given.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.386-389
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• 2007

Currently, fast and accurate long baseline positioning in kinematic mode is a challenging topic, but positional accuracy can be improved with the help of the network-derived external ionospheric corrections. To provide not only ionospheric corrections, but also their variances, satellite-by-satellite interpolation for the ionospheric delays is performed using the least-squares collocation (LSC) method. Satellite-by-satellite interpolation has the advantage in that the vertical projection used in single-layer ionospheric model is not required. Also, more reliable user positioning and the corresponding accuracy assessment can be obtained by providing not only external ionospheric corrections but also their variances. The rover positioning with and without the external ionospheric delays in both rapid-static and kinematic mode was performed and analyzed. The numerical results indicate that the improvement in the positioning quality is achieved using the proposed method. With the TAMDEF network in Antarctica, 18 % improvement in mean time-to-fix in kinematic mode was achieved.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.5
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• pp.73-78
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• 2011

We developed a noise reduction algorithm for the measurement accuracy improvement of a fiber-optic distributed temperaure sensor system. The denoising technique is based on the wavelet transform. The proposed algorithm was applied to a FBG sensor output with the Gaussian line-fitting algorithm to minimize the output noise which originated from the intensity noise of the laser light source and the instability of signal porcessing. We confirmed the feasibility of the denoising algorithm by comparing the measurement results with those obtained with the Gaussian line-fitting algorithm only.

• Journal of the Korean Society of Safety
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• v.24 no.4
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• pp.11-16
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• 2009

This research investigates contact angle of Linear Guide Way through a experimental result and theoretical analysis. Since last ten years, most of researchers who concerned with the precision machinery and semiconductor device production etc. so the researches about Linear Guide Way have been unnoticed. The precision machinery and semiconductor device production system has the principle which transfers the mechanical moving to accuracy position control. The Linear Guide Way system has the principle which transfers mechanical moving to accuracy position control is very important to improve performance of the precision machinery and semiconductor device production system. So, In this research, in order to improvement for producing Linear Guide Way, bearing loading analysis and contact angle change through Linear Guide Way theoretical analysis and bearing modeling. Through this study, we may expect that there will be more improvement for producing Linear Guide Way.

• International journal of advanced smart convergence
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• v.10 no.2
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• pp.73-78
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• 2021

Recently, the number of people who visit the hospital due to diabetes is increasing. According to the Korean Diabetes Association, it is statistically indicated that one in seven adults aged 30 years or older in Korea suffers from diabetes, and it is expected to be more if the pre-diabetes, fasting blood sugar disorders, are combined. In the last study, the validity of Triglyceride and Cholesterol associated with diabetes was confirmed and analyzed using Random Forest. Random Forest has a disadvantage that as the amount of data increases, it uses more memory and slows down the speed. Therefore, in this paper, we compared and analyzed Random Forest and XGBoost, focusing on improvement of learning speed and prevention of memory waste, which are mainly dealt with in machine learning. Using XGBoost, the problem of slowing down and wasting memory was solved, and the accuracy of the diabetes recognition factor was further increased.

• ETRI Journal
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• v.46 no.1
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• pp.137-153
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• 2024

This study introduces a new approach in Korean morphological analysis combining dictionary-based techniques with Transformer-based deep learning models. The key innovation is the use of a BERT-based reranking system, significantly enhancing the accuracy of traditional morphological analysis. The method generates multiple suboptimal paths, then employs BERT models for reranking, leveraging their advanced language comprehension. Results show remarkable performance improvements, with the first-stage reranking achieving over 20% improvement in error reduction rate compared with existing models. The second stage, using another BERT variant, further increases this improvement to over 30%. This indicates a significant leap in accuracy, validating the effectiveness of merging dictionary-based analysis with contemporary deep learning. The study suggests future exploration in refined integrations of dictionary and deep learning methods as well as using probabilistic models for enhanced morphological analysis. This hybrid approach sets a new benchmark in the field and offers insights for similar challenges in language processing applications.