• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.155-165
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• 2010

The purpose of this study was to analyze kinematic quantitative factors required of a forehand counter drive in table tennis through 3-D analysis. Four national table tennis players participated in this study. The mean of elapsed time for total drive motion was $1.009{\pm}0.23\;s$. At the phase of impact B1 was the fastest as 0.075 s. This may affect efficiency in the initial velocity and spin of the ball by making a powerful counter drive. The pattern of center of mass showed that it moved back and returned to where it was then moved forward. At the back swing, lower stance made wide base of support and a stronger and safer stance. It may help increasing the ball spin. Angle of the elbow was extended up to $110.75{\pm}1.25^{\circ}$ at the back swing and the angle decreased by $93.75{\pm}3.51^{\circ}$ at impact. Decreased rotation range of swinging arm increased linear velocity of racket-head and impulse on the ball. Eventually it led more spin to the ball and maximized the ball speed. Angle of knee joint decreased from ready position to back swing, then increased from the moment of the impact and decreased at the follow thorough. The velocity of racket-head was the fastest at impact of phase 2. Horizontal velocity was $7796.5{\pm}362\;mm/s$ and vertical velocity was $4589.4{\pm}298.4\;mm/s$ at the moment. It may help increase the speed and spin of the ball in a moment. The means of each ground reaction force result showed maximum at the back swing(E2) except A2. Vertical ground reaction force means suggest that all males and females showed maximum vertical power(E2), The maximum power of means was $499.7{\pm}38.8\;N$ for male players and $519.5{\pm}136.7\;N$ for female players.

• Journal of the Korean earth science society
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• v.30 no.6
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• pp.734-743
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• 2009

In order to examine how climatological condition can influence on urban scale particulate air pollutants, single and cross spectrum analysis have been performed to daily mean concentrations of particulate matters ($PM_{10}$) in Busan together with the climatological variables over the Asian dust source regions. Single power spectrum analysis of $PM_{10}$ concentrations in Busan shows that, aside from the typical and well-known periodicities, 3-4 year of peak periodicity of power spectrum density was identified. In cross spectrum analysis, this 3-4 year periodicity is found to have a strong positive correlation with the wind speed and pressure, and negative with the temperature and relative humidity, which is rather consistent with both characteristics of air mass during the Asian dust event whose periodicities have been recorded inter-annually over the Korean urban cities. Over the Asian dust source regions, $PM_{10}$ vs. precipitation shows no significant periodicity from the time series of precipitation data, but the periodicity of EDI (Effective Drought Index) shows some interannual variabilities ranging from 2 to 4 years over the various source regions, suggesting that, rather than precipitation itself, the EDI could be more closely associated with the occurrence frequency of Asian dust and interannual variability of urban particle concentrations in Korean cities.

• Korean Educational Research Journal
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• v.42 no.1
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• pp.1-34
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• 2021

The thesis tries to compare The Structure of World History with Anti-Oedipus in the textual context, and to re-compare in the educational context. I mean by the education an event which contrasts starkly with an essence. It adopts 5W1H, a general reporting form of an accident or event, as the distinctive features at twice comparisons. The purpose of the thesis is not evaluative but interpretive comparison. In the textual context, the thesis discusses, 1) as WHAT, the use of Marx from Kant vs. Nietzsche's point of view, 2) as WHO, the actual subjects of the exchanging human vs. the productive machine, 3) as WHEN/WHERE, the society of the modes of exchange vs. the modes of inscription, 4) as HOW, the revolutionay means of the simultaneous revolution of the world vs. the schizophrenic process, 5) as WHY, the ideal subjects of the associative human vs. the non-human of liberation of desire. In the educational context, the thesis discusses, 1) in the WHAT as educational way, autonomous morality vs. active power, 2) in the WHO as the affirmity of actual subjects, that of the ideal idea vs. that of real power, 3) in the WHEN/WHERE, as the in-between time-space of education, the incommensurable communicative situation of humans vs. the conflictive of machines, 4) in the HOW, as the educational method of achieving the ideal, the involuntary restoration of the already-had ideal vs. the now-have completion and break-through of the schizophrenic process, 5) in the WHY, as the aim of education, cosmopolitan vs. overman.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.1
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• pp.34-44
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• 2021

In order to collect basic information of response behavior of red seabream (Pagrus major) during pilling, works for constructing wind power station in Byeonsan Peninsular, Korea were investigated. Four cultured red seabream CRB1 to CRB4 [total length (TL): 27.1 ± 1.0 cm; body weight: 359 ± 30 g] were tagged with an acoustic tag and used in experiment. CRB1 and CRB2 to CBR4 were released on the sea surface at same time around the constructing site of the wind power plant on September 22, 2017 and July 18, 2018, respectively. The tracking of the CRB1 to CRB2 and CRB3 to CRB4 were conducted for two hours, approximately, using VR100 receiver including a directional hydrophone and VR2W receivers array consisted of 19 presence/absence receivers (VR2W receivers), respectively. The underwater noise level before (no pile driving works) and during pile driving works was measured 116.0-118.0 dB (re 1��Pa) and a maximum of 160 dB (re 1��Pa), respectively. CRB1 moved about 6.0 km with average swimming speed of 80.2 ± 20.5 cm/s for 2.1 hours without pile driving work. The average water depth of the sea bed on the route of CRB1 was 9.1 ± 0.4 m. CRB2 moved about 7.3 km with the average swimming speed of 96.8 ± 27.1 cm/s for 2.1 hours with pile driving work. The water depth of the sea bed on the route of CRB2 was 11.9 ± 0.6 m. At results of the Rayleigh's z-test two fishes CRB1 and CRB2 showed significant directionality in the movement (p < 0.01). Movement mean angles of CRB1 and CRB2 were 92.7 and 251.8°, respectively. CRB2, CRB3 and CRB4 exhibited the escaping behavioral response from the noise of source during the pile driving work. The swimming speed of the CRB2 exposed on the heavy underwater noise stimuli due to the pile driving work was 1.21 times faster than that of the CRB1 exposed on the ambient underwater noise in the study site.

• Journal of dental hygiene science
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• v.10 no.1
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• pp.11-16
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• 2010

The subjects of this study were patients at scaling practice, the total number of the subjects was 249 of 138 men and 111 women. The results were analyzed using SPSS 12.0. 1. In oral health care, among tooth brushing methods, scrub method was found to be 65.9%(164 patients), and 83.9%(209 patients) did not use oral care aids. 2. Mean calculus index was $0.57{\pm}0.22$. 3. For calculus index per tooth brushing method, there was statistically significant difference in all of the upper jaw, the lower jaw, the anterior portion, and the posterior portion(p < 0.05). 4. For calculus index per frequency of tooth brushing, there was statistically significant difference in the upper jaw, the lower jaw, and the posterior portion(p < 0.05). 5. For calculus index per time of tooth brushing and per use of oral care aids, there was statistically significant difference in all of the upper jaw, the lower jaw, the anterior portion, and the posterior portion(p < 0.05). 6. For factors influencing calculus index, as a result of applying stepwise method based on 0.05 of significance level, age, use of oral care aids, sex, and time of tooth brushing were found to influence calculus index. Final regression model was calculus index = $0.362^*age+0.216^*$use of oral care aids - $0.161*sex-0.127^*$time of tooth brushing, and explanatory power of the model was 23.4%. $0.362^*age+0.216^*$use of oral care aids - $0.161^*sex-0.127^*$time of tooth brushing, and explanatory power of the model was 23.4%.

• Journal of the Korean earth science society
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• v.41 no.2
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• pp.95-110
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• 2020

Comparisons between two different surface temperatures from high-resolution ECMWF ReAnalysis 5 (ERA5) and Automated Synoptic Observing System (ASOS) observations were performed to investigate the reliability of the new reanalysis data over South Korea. As ERA5 has been recently produced and provided to the public, it will be highly used in various research fields. The analysis period in this study is limited to 1999-2018 because regularly recorded hourly data have been provided for 61 ASOS stations since 1999. Topographic characteristics of the 61 ASOS locations are classified as inland, coastal, and mountain based on Digital Elevation Model (DEM) data. The spatial distributions of whole period time-averaged temperatures for ASOS and ERA5 were similar without significant differences in their values. Scatter plots between ASOS and ERA5 for three different periods of yearlong, summer, and winter confirmed the characteristics of seasonal variability, also shown in the time-series of monthly error probability density functions (PDFs). Statistical indices NMB, RMSE, R, and IOA were adopted to quantify the temperature differences, which showed no significant differences in all indices, as R and IOA were all close to 0.99. In particular, the daily mean temperature differences based on 1-hour-averaged temperature had a smaller error than the classical daily mean temperature differences, showing a higher correlation between the two data. To check if the complex topography inside one ERA5 grid cell is related to the temperature differences, the kurtosis and skewness values of 90-m DEM PDFs in a ERA5 grid cell were compared to the one-year period amplitude among those of the power spectrum in the time-series of monthly temperature error PDFs at each station, showing positive correlations. The results account for the topographic effect as one of the largest possible drivers of the difference between ASOS and ERA5.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1641-1648
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• 2017

Many researchers had examined the validity of using the high-to-low ratio between two fixed frequency band amplitudes (H/L-FFB) from the surface electromyography of a face and body as the first spectral index to assess muscle fatigue. Despite these studies, the disadvantage of this index is the lack of a criterion for choosing the optimal border frequency. We tested the potential of using the high-to-low ratio between two signal spectral moments (H/L-SSM), without fixed border frequencies, to evaluate muscle fatigue and predict endurance time ($T_{end}$), which was determined when the subject was exhausted and could no longer follow the fixed contraction cycle. Ten healthy participants performed five sets of voluntary isotonic contractions until they could only produce 10% and 20% of their maximum voluntary contraction (MVC). The $T_{end}$ values for all participants were $138{\pm}35s$ at 10% MVC and $69{\pm}20s$ at 20% MVC. Changes in conventional spectral indices, such as the mean power frequency (MPF), Dimitrov spectral index (DSI), H/L-FFB, and H/L-SSM, were extracted from surface EMG signals and were monitored using the initial slope computed every 10% of $T_{end}$ as a statistical indicator and compared as a predictor of $T_{end}$. Significant correlations were found between $T_{end}$ and the initial H/L-SSM slope as computed over 30% of $T_{end}$. In conclusion, initial H/L-SSM slope can be used to describe changes in the spectral content of surface EMG signals and can be employed as a good predictor of $T_{end}$ compared to that of conventional spectral indices.

• The Journal of the Acoustical Society of Korea
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• v.23 no.6
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• pp.446-453
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• 2004

In this paper, a new adaptive perceptual filter using variable threshold to enhance audio signals degraded by additively nonstationary noise is proposed. The adaptive perceptual filter updates variable threshold each time according to the power of signal and the effect of noise variation. So the noisy audio signal is enhanced by the method which controls a residual noise effectively. The proposed algorithm uses the perceptual filter which transforms a time domain signal into frequency domain and calculates an intensity energy and an excitation energy in bark domain. In this method. the stage updated the response of filter is decided by threshold. The proposed algorithm using vairable threshold effectively controls a residual noise using the energy difference of audio signals degraded by the additive nonstationary noise. The proposed method is tested with the noisy audio signals degraded by nonstationary noise at various signal -to-noise ratios (SNR). We carry out NMR and MOS test when the input SNR is 15dB. 20dB. 25dB and 30dB. An approximate improvement of 17.4dB. 15.3dB, 12.8dB. 9.8dB in NMR and enhancement of 2.9, 2.5, 2.3, 1.7 in MOS test is achieved with the input signals. respectively.

• Journal of Wetlands Research
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• v.7 no.4
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• pp.97-107
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• 2005

As the distributed model is developed and widely used, the accuracy of a rainfall measurement and more dense rainfall observation network are required for the reflection of various spatial properties. However, in reality, it is not easy to get the accurate data from dense network. Generally, we could not have the proper rainfall gages in space and even we have proper network for rainfall gages it is not easy to reflect the variations of rainfall in space and time. Often, we do also have missing rainfall data at the rainfall gage stations due to various reasons. We estimate the distribution of mean areal rainfall data from the point rainfalls. So, in the aspect of continuous rainfall property in time, we should fill the missing rainfall data then we can represent the spatial distribution of rainfall data. This study uses the Fuzzy-Genetic algorithm as a interpolation method for filling the missing rainfall data. We compare the Fuzzy-Genetic algorithm with arithmetic average method, inverse distance method, normal ratio method, and ratio of distance and elevation method which are widely used previously. As the results, the previous methods showed the accuracy of 70 to 80 % but the Fuzzy-Genetic algorithm showed that of 90 %. Especially, from the sensitivity analysis, we suggest the values of power in the equation for filling the missing data according to the distance and elevation.

• Journal of Acupuncture Research
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• v.27 no.1
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• pp.87-100
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• 2010

Background : Recently a discussion about Qi including a study about the effect or the theory of acupuncture is getting prevailing in various angles. In most of studies about acupuncture stimulus, 'Filiform acupuncture'(毫鍼) is used. A study about Nine kinds of acupuncture(九鍼), except 'Filiform acupuncture'(毫鍼) has not been reported yet, and there is no study about using a special acupuncture made for controling Qi either. Objectives : 'Dong Chu Gold Chim(DCG-chim, 東樞金鍼)' can be used for patients who are scared of a pain because it is a medical Qi-gong tool and non-invasive stimulus one. To assess a effect of Qi-gong operation using DCG-chim objectively Methods : The present study was performed to elucidate the effects of DCG-chim stimulation of an acupuncture point Baihui($GV_{20}$) on the Electroencephalogram(EEG). Twenty healthy subject were treated with DCG-chim one time accompanied by the light and vertical pressure and EEG were measured during five minutes for three times (before, during and after treatment). The EEG results of DCG-chim treatment were compared with those of 'Filiform acupuncture(毫鍼)'. Results : EEG power spectra changed significantly after both kind of acupuncture stimulation. Significant increase of $\alpha$ wave and decrease of $\beta$ wave were observed but interestingly, Mid-$\beta$ and SMR of $\beta$ wave which mean the state of concentration were increased with statistically significant. According to these results, DCG-chim stimulation of Baihui($GV_{20}$) seems to lead to relaxation with antianxietic effect and improvement of concentration at the same time. Conclusions : It would be expected that the doctor can apply DCG-chim for treating anxiety, tension, symptom caused by stress and also can use it clinically for patients who have needlphopia or children as a non-invasive procedure. It is suggested that additional studies about the effect of DCG-chim on other acupuncture points and comparison study about the effect of DCG-chim with those of the finger-pressure treatment using other tool should be done in the future.