• Journal of KSNVE
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• v.7 no.5
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• pp.747-756
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• 1997

Wigner-Ville distribution which is a time-frequency analysis has a fatal drawback, when the signal has multiple components. This is the cross-talk and often causes a neagative value in the distribution. Wingner-Ville distriution is an expression of power, therefore the cross-talk must be avoided. Smoothing the Wigner-Ville distribution by convoluting it with a window, is most commonly used to reduce the cross-talk. There can be infinite number of distributions depending on the windows. But, the smoothing reduces resolution in time-frequency plane; this motives to design a more effective window in reducing cross-talk while remaining resolution. The domain in which the cross-talk and legitimate components can be easily distinguished, is the ambiguity function. In the ambiguity function domain, the legitimate components appear as linear lines passing through the orgine. But, the cross-talk is widely distributes in the ambiguity function plane. Based on the relative distributions of cross-talk and legitimate components, rotating window can be designed to minimize cross-talk. Applying the rotating window to the ambiguity function corresponds to smoothing the Wigner-Ville distribution. Therefore, the effects of rotating window is estimated in terms of the bias error due to smooting the Wigner-Ville distribution. By applying the rotating window, not only the Wigner-Ville distribution but also its properties are changed. The properties of the new distribution are checked, in order to complete analyzing the rotating window.

• Journal of KSNVE
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• v.7 no.2
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• pp.319-329
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• 1997

Wigner-Ville distribution has been recognized as a useful tool and applied to various types of mechanical noise and vibration signals, but its limitation which mainly comes from the cross-talk has not been well addressed. The cross-talk takes place for a signal with multiple components, simply because the Wigner-Ville distribution is a bilinear transform. The cross-talk often causes a negative value in the distribution. This cannot be accepted for the Wigner- Ville distribution, because it is an expression of power. Smoothing the Wigner-Ville distribution by convoluting it wih a window, is most commonly used to reduce the cross-talk. There can be infinite number of distributions depending on the windows. In this paper, we attempted to develop a distribution which is the best or the optimal in reducing the cross-talk. This could be possible by employing the ambiguity function. For a general signal, however it is difficult to express the ambiguity function as a mathematically closed form. This requires an appropriate modeling to make such expression possible. We approximated the Wigner-Ville distribution as a sum of linear segments. In the ambiguity function domain, the legitimate components are reflected as linear lines passing through the origin. Every lines has its own length and slope. But, the cross-talk is widely distributed in the ambiguity function plane. Based on this realization, we proposed a two-dimensional window which is in fact 'rotating window', that can eliminate cross-talk component. The rotating window is examined numerically and is found to have a better performance in reducing the cross-talk than conventional windows, the Gaussian window.

• Journal of Digital Convergence
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• v.17 no.6
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• pp.327-333
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• 2019

The purpose of this study is to suggest areas for improvement of KakaoTalk. KakaoTalk is used by everyone in Korea, and even elementary school students have been using it a lot recently. Therefore, to help parents feel safe about their children using KakaoTalk, and to ensure that children are not worried about their parents when using them, I would like to examine each user's experience to pinpoint the problem. As a method of study, a survey and interview was conducted on eight parents and eight children using KakaoTalk. Through this, the parents could not trust KakaoTalk in terms of reliability when they saw their children using KakaoTalk. Based on this research, we hope to improve KakaoTalk through further research so that parents and children can use Kakao Talk safely.

• The Journal of the Korea Contents Association
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• v.22 no.1
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• pp.359-367
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• 2022

The purpose of this study is to examine the perception of college students about English classes using TED talks and to examine whether TED talks are appropriate as a learning material for college English. As a college English subject, 50-60 minutes of online classes were conducted for one semester where TED talks were used, and the data collected by conducting a survey on learners' English learning motivation, interest, attitude, satisfaction, and learning effect were analyzed utilized SMART PLS 3. The results are as follows. First, English learning motivation had a statistically significant effect on learning attitude while it did not affect the learning satisfaction. Second, the level of interest in the TED Talk-using class had a positive effect on the learning attitude and satisfaction. Third, the learning attitude positively affected the learning effect perception. Fourth, satisfaction with the TED Talk class had a positive effect on the learning effect perception. In conclusion, English classes using TED talk can increase the interest and satisfaction of learners, and induce active class participation, which lead to a positive perception in learners' learning effects. Therefore, this study implies that TED talks are valuable and significant enough as materials in college English classes.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.4
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• pp.17-25
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• 2023

Purpose: This study aimed to examine the effectiveness of a suicide prevention education program called "Life Talk Talk" among middle and high school students in D City. Methods: The educational content of the "Life Talk Talk" program was compiled through nine rounds of consultations and meetings with suicide prevention experts. Prior to the implementation of the program, consent was obtained from all research participants and their guardians. First , a pilot study was conducted with 100 middle and high school students located in D city, following which the present study was conducted from May to July 2023 with 1,400 middle and high school students in D city. The effects of the program were evaluated by assessing the changes in suicidal ideation, help-providing abilities, and suicide prevention knowledge in the data collected both before and after the education. Statistical analysis included frequency analysis and a paired-sample t-test. Results: The final analysis included 1,380 participants. In the general characteristics,, 1,079 people (78 %) answered "yes" to the question about suicide prevention education experience . The study found a significant decrease in suicidal attitudes (t=-8.92, p<.001) and significant improvements in emotional and cognitive attitudes of participants after the "Life Talk Talk" program . Additionally, all five items related to help-providing abilities (t=-23.83, p<.001) and suicide prevention knowledge (p<.001) showed significant improvement from before the program. Conclusion: The significance of this study lies in demonstrating the effectiveness of the "Life Talk Talk" suicide prevention education program in reducing suicidal attitudes as well as improving help-providing abilities and suicide prevention knowledge. Therefore, to enhance the effectiveness of suicide prevention education, it is essential to regularly implement concise and engaging educational programs that capture the attention of adolescents.

• Journal of the Korea Society for Simulation
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• v.2 no.1
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• pp.107-124
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• 1993

This paper presents an object -oriented simulation approach. AgvTalk, to design and analze AGV system configuration and control. Smalltalk-80 is used as an implementation language in AgvTalk. AgvTalk includes 25 object classes and more than 300 object methods in its library. Compared to general purpose simulation languages. AgvTalk provides several important benefits. First, the hierarchical features and modularity create possibilities for the extension and reuse of simulation object components. This extensibility and reusability provide more flexible modeling capabilities for simulation of many alternative AGV systems. Second, detailed behavior of each object in the AGV system can be modeled easily and exactly in AgvTalk because there are no limiting modeling constructs. Third, AgvTalk provides a user -friendly simulation modeling environment through the MVC -triad of Smalltalk-80.

• IE interfaces
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• v.8 no.2
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• pp.135-150
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• 1995

An object-oriented simulation modeling environment, AgvTalk, is presented to provide flexible modeling capabilities for simulation of many alternative AGV systems. The hierarchical features and modularity of AgvTalk create possibilities for the extension and reuse of simulation object components. Also, detailed behavior of each object in the AGV system can be modeled easily and exactly in AgvTalk because there are no limiting modeling constructs. The modeling capabilities of AgvTalk is demonstrated by designing and simulating a conceptually different configuration of AGV systems, known as, the tandem configuration. Between the tandem and conventional AGV systems, the characteristics and design methodology in AgvTalk are described. Also, simulations between two systems are compared with AgvTalk in the job shop environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5C
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• pp.478-486
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• 2007

Double-talk detection errors can result in either large residual echo or distorting the near-end talker's input speech. Thus accurate double-talk detection is an important problem in the acoustic echo canceller to improve the speech quality. In the double-talk detection algorithm using a cross-correlation coefficient, double-talk detection errors can occur in the initial convergence period of an adaptive filter or in noisy environment since the cross-correlation coefficient becomes large in such situations. In this paper, we propose a new double-talk detection algorithm based on the cross-correlation method using a normalized error signal power to reduce the double-talk detection errors. The experimental results have shown the performance improvement of an acoustic echo canceller as well as the noise-robustness of the proposed double-talk detector.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.73-79
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• 2011

Inkjet printhead may have a lot of nozzles to increase productivity as a manufacturing tool. So, the uniformity of jetting performance among a lot of nozzles has been one of the key issues in inkjet technology In this study, we investigated the cross-talk effect which should be reduced for uniform jetting performance among a lot of nozzles. Due to the cross-talk, the jetting performance of a nozzle can be affected when neighboring nozzles are firing. For experimental study, we used commercial inkjet head SE-128 from Dimatix. To understand the cross-talk effect of SE-128 head, we measured the change in jetting speed of a nozzle when neighboring nozzles are jetting. The measured jetting speed was compared to the case of one nozzle jetting. Also, we used laser vibrometer to measure change in pressure wave due to cross-talk. As a result of the cross-talk, the jetting speed can become faster or sometimes slower depending on firing nozzle location. If the all nozzle are jetting, the jetting speed of a nozzle became slower because the pressure wave for jetting is reduced.

• Annual Conference on Human and Language Technology
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• 2021.10a
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• pp.293-299
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• 2021

본 논문은 외국어 학습을 위한 딥러닝 기반 영어 교육 플랫폼인 PEEP-Talk (Personalized English Education Platform)을 제안한다. PEEP-Talk는 딥러닝 기반 페르소나 대화 시스템과 영어 문법 교정 피드백 기능이 내장된 교육용 플랫폼이다. 또한 기존 페르소나 대화시스템과 다르게 대화의 흐름이 벗어날 시 이를 자동으로 판단하여 대화 주제를 실시간으로 변경할 수 있는 CD (Context Detector) 모듈을 제안하며 이를 적용하여 실제 사람과 대화하는 듯한 느낌을 사용자에게 줄 수 있다. 본 논문은 PEEP-Talk의 각 모듈에 대한 정량적인 분석과 더불어 CD 모듈을 객관적으로 판단할 수 있는 새로운 성능 평가지표인 CDM (Context Detector Metric)을 기반으로 PEEP-Talk의 강건함을 검증하였다. 이와 더불어 PEEP-Talk를 카카오톡 채널을 이용하여 배포하였다.