• Journal of Industrial Technology
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• v.27 no.B
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• pp.21-27
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• 2007

The power line channel has time-variant characteristics caused by various kind of electrical devices. This characteristics are synchronized with the main voltage by their own characteristics. The main factors of disturbance are the variation of the channel impedance and noises. In other papers, the synchronous noise modeling has been achieved. But the modeling is not satisfied simultaneously with the time domain and the frequency domain and there are not any discussion about short-term variations of the channel impedance which cause to the signal fading. Therefore, this paper researched to solve problems about the signal fading by analyzing the short-term variation of the channel impedance, and proposed the synchronous noise modeling which is satisfied simultaneously in the time domain and the frequency domain.

• Journal of Environmental Science International
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• v.7 no.5
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• pp.599-605
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• 1998

The purpose of this work was to examine whether X-Y chromosome dissociation in the primary spermatocytes of mice could be used as an in vivo short-term assaying system that detect environmental mutagens. Four alkylating agents(EMS, MMS, MMC and MNNG) which were known as strong mutagens were administered to BALB/c male mice 3-4 months old. In the control group, the mean frequencies of previously dissociated X and Y chromosomes and autosomes were 7.17% and 2.12%, respectively. Compared to the control group, mutagen-treated groups have no significant differences in dissociation rate of autosomes, while these poops were about 1.2-2.5 times higher in the frequencies of X-Y dissociation. Generally, X-Y dissociation frequency increased consistently with the concentration of mutagens whereas the tendency of autosome dissociation frequency was variable among several mutagens. These results suggest that X-Y dissociation in the primary spermatocytes of mice is applicable as an vivo short-term assaying system for environmental mutagens. There were significantly distinct increase in dissociation of X-Y chromosome in both the hybrid and parents but the X-Y previous dissociation of hybrid appeared higher frequency than BALB /c and wild mice. These results indicate that the factor related to binding X-Y chromosome is specific to strains.

• Smart Structures and Systems
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• v.31 no.1
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• pp.45-56
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• 2023

Vibration-based structural health monitoring is used to ensure the safety of structures by installing sensors in structures. The peak picking method, one of the applications of vibration-based structural health monitoring, is a method that analyze the dynamic characteristics of a structure using the peaks of the frequency response function. However, the results may vary depending on the person predicting the peak point; further, the method does not predict the exact peak point in the presence of noise. To overcome the limitations of the existing peak picking methods, this study proposes a new method to automate the modal analysis process by utilizing long short-term memory, a type of recurrent neural network. The method proposed in this study uses the time series data of the frequency response function directly as the input of the LSTM network. In addition, the proposed method improved the accuracy by using the phase as well as amplitude information of the frequency response function. Simulation experiments and lab-scale model experiments are performed to verify the performance of the LSTM network developed in this study. The result reported a modal assurance criterion of 0.8107, and it is expected that the dynamic characteristics of a civil structure can be predicted with high accuracy using data without experts.

• ETRI Journal
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• v.26 no.5
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• pp.391-396
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• 2004

In this paper, we propose a packet scheduling discipline called packet loss fair scheduling, in which the packet loss of each user from different real-time traffic is fairly distributed according to the quality of service requirements. We consider an orthogonal frequency division multiple access (OFDMA) system. The basic frame structure of the system is for the downlink in a cellular packet network, where the time axis is divided into a finite number of slots within a frame, and the frequency axis is segmented into subchannels that consist of multiple subcarriers. In addition, to compensate for fast and slow channel variation, we employ a link adaptation technique such as adaptive modulation and coding. From the simulation results, our proposed packet scheduling scheme can support QoS differentiations while guaranteeing short-term fairness as well as long-term fairness for various real-time traffic.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.230-237
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• 2022

The Community Social Service Investment project started as a state subsidy project in 2007 and has grown very rapidly in quantitative terms in a short period of time. It is a bottom-up project that discovers the welfare needs of people and plans and provides services suitable for them. The purpose of this study is to analyze using big data to determine the social response to local community service investment projects. For this, data was collected and analyzed by crawling with a specific keyword of community service investment project on Google and Naver sites. As for the analysis contents, monthly search volume, related keywords, monthly search volume, search rate by age, and gender search rate were conducted. As a result, 10 items were found as related keywords in Google, and 3 items were found in Naver. The overall results of Google and Naver sites were slightly different, but they increased and decreased at almost the same time. Therefore, it can be seen that the community service investment project continues to attract users' interest.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.1
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• pp.88-95
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• 1989

The aspects of the occurence frequency of $SO_2$ concentration were studied with the observed data in Seoul and the scheme that is capable of estimating not only highest concentration for a variety of averaging times but also concentrations for arbitary occurrence frequency with long term arithmatic mean and geometric standard deviation data, was evaluated. The results of the statistical analysis show that the occurrence frequency is almost log normal except a few cases, and 3rd highest values of daily mean concentration were about 4.2 $\sim$ 5.2 times higher than annual arithmatic mean. The evaluation with the observed hourly concentration shows that the scheme fairly well estimate the short concentration of arbitary occurrence frequence and it can be used for air quality management and environmental impact assessment.

• Physical Therapy Korea
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• v.8 no.1
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• pp.9-19
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• 2001

During therapy sessions, feedback is often provided concurrently by the physical therapist as the patient attempts to perform a movement and after the movement attempt. This feedback is provided to enhance the patient's balance abilities. However, recent studies in nondisabled populations have suggested that frequent feedback may be detrimental to retention or learning of motor skills. This study compared the effects of 100% relative frequency of knowledge of performance (KP) with 66% relative frequency of KP for motor learning on balance retraining in patients with hemiplegia. Twenty patients with hemiplegic were randomly assigned to one of two experimental groups. The acquisition phase consisted of 16 blocks of 5 trials for 2 days (80 total practice trials). The retention phase consisted of 2 blocks of a short-term retention test, one day after the end of the acquisition phase and a long-term retention test, one week after the end of the short-term retention test. In the 100% feedback condition, participants received feedback after every practice trial. A faded KP schedule was used in the 66% condition. No significant differences were found between the two groups during all experimental phases (acquisition and retention phases), (p>.05). However, there were significant decreases in balance index for both groups of acquisition phase (p<.05). These results suggest that 66% relative frequency of KP is not more effective than 100% relative frequency of KP with respect to retention over time when hemiparetic patients attempt to learn balance.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.227-228
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• 1996

The long-term light curves of the novalikes TT Ari, KR Aur, AM Her and MV Lyr, were compiled and analysed for solar-like cyclical behaviour. The frequency analysis showed long-term cyclical modulations of the brightness of the stars, which can be ascribed to changes of the radii of the late type secondaries in order of ${\Delta}R/R{\simeq} 10^{-4}-10^{-5}$.

• Journal of Korean Library and Information Science Society
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• v.34 no.3
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• pp.211-229
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• 2003

In this paper, we have focused that the number of word in the web document affects definite clustering performance. Our experimental results have clearly shown the relationship between the amounts of word and its impact on clustering performance. We also have presented an algorithm that can be supplemented of the contrast portion through co-links frequency of web documents. Testing bench of this research is 1,449 web documents included on 'Natural science' category among the Naver Directory. We have clustered these objects by term-based clustering, link-based clustering, and hybrid clustering method, and compared the output results with originally allocated category of Naver directory.

• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.213-219
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• 2015

This study examines how the features of communication on Social Network Service(SNS) affect building faculty trust and long-term orientation in professor-student relationships. The research model was developed based on the previous research about communication, SNS and relationship development. The researcher surveyed 210 students to collect research data, and 195 questionnaires were analyzed using SmartPLS. The results indicate that the quality, frequency, interactivity and openness of communication on SNS affect positively on faculty trust. Moreover, the quality, frequency and openness of communication on SNS affect positively on long-term orientation, whereas interactivity does not. This mean that faculty trust plays a mediating role between interactivity and long-term orientation.