• 천문학회보
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• 제38권1호
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• pp.61.2-61.2
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• 2013

We study chromospheric oscillations including umbral flashes and running penumbral waves in a sunspot using scanning spectroscopy in H-alpha and Ca II 8542A, with the Fast Imaging Solar Spectrograph (FISS) at the 1.6 meter New Solar Telescope at Big Bear Solar Observatory. A bisector method is applied to spectral observations to construct chromospheric Doppler velocity maps. Temporal sequence analysis of these shows enhanced high-frequency oscillations inside the sunspot umbra in both lines. Their peak frequency gradually decreases outward from the umbra. The oscillation power is found to be associated with magnetic-field strength and inclination, with different relationships in different frequency bands.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.38-40
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• 1988

This paper was a study on dielectic characteristics of polypropylen film which were annealled in air and qunched in nitorgen after aging for 5[Hr]. Dielectric characteristics of specimen were measured in temperature of the range of 15-120[$^{\circ}C$], and in frequency of the range of $30-1{\times}10^6$[Hz.] As the result, for dielectric relaxation $\beta$-peak was observed in 20[$^{\circ}C$], and $\alpha$-peak was observed in 90[$^{\circ}C$]. Also, it was explained that $\alpha$-peak attributed due to armorphous region and $\beta$-peak attributed due to crystalline region and activation energy from dielectric loss spectra was obtained 34.5[kcal/mole] for $\alpha$-peak and 80.5[Kcal/mole] for $\beta$-peak, respectively.

• 말소리와 음성과학
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• 제2권3호
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• pp.37-46
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• 2010

This study investigates acoustic characteristics of English and Korean voiceless sibilant fricatives as they appear before the three vowels, /i/, /$\alpha$/ and /u/. Three measurements - duration, center of gravity and major spectral peak - are employed to compare acoustic properties and vowel effect for each fricative sound. This study also investigates the question of whether Korean sibilant fricatives are acoustically similar to the English voiceless alveolar fricative /s/ or to the palato-alveolar /$\int$/. The results show that in the duration of frication noise, English /$\int$/ is the longest and Korean lax /s/ the shortest of the four sounds. It is also observed that English alveolar /s/ has the highest value, whereas Korean /s/ shows the lowest value in the frequency of center of gravity. In terms of major spectral peak, while English /s/ reveals the highest frequency, English /$\int$/ shows the lowest value. In addition, evidence indicates that there is a strong vowel effect in the fricative sounds of both languages, although the vowel effect patterns of the two languages are inconsistent. For instance, in the major spectral peak, both Korean lax /s/ and tense /$s^*$/ show significantly higher frequencies before the vowel /$\alpha$/ than before the other vowels, whereas both English /s/ and /$\int$/ exhibit significantly higher frequencies before the vowel /i/ than before the other vowels. These results indicate that Korean sibilant fricatives are acoustically distinct from both English /s/ and /$\int$/.

• E2M - 전기 전자와 첨단 소재
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• 제1권1호
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• pp.54-61
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• 1988

This paper was a study on dielectric phenomena of the specimen, Polypropylene films which were annealled in air and quenched in liquid nitrogen after aging for 5[hr] in water of 100[.deg.C]. The specimen was measured in temperature range of 15-120[.deg.C] and in frequency range of 30-1x 10$^{6}$ [HZ]. As the results of the study, it was confirmed that the tacticity of specimen was isotactic structure, and the degree of cryatallinity of the specimens calculated by means of Natta's method from XRD (X-ray Diffraction) spectrum was 55[%]. And for dielectric relaxation, .betha. peak-the tan .delta. (spectrum around 20[.deg.C])-attributed due to amorphous regions, and .alpha. peak - the tan .delta. spectrum around 90[.deg.C]-due to crystalline regions. It was identified that the degree of crystallinity of the specimen quenched in the liquid nitrogen was increased to 55-65[%], and that of the specimen annealled in the air was decreased to 55-50[%]. And activation energy from dielectric loss spectra was obtained 34.5[kcal/mole] for .alpha. peak and 80.5[kcal/mole] for .betha. peak, respectively.

• 전기전자학회논문지
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• 제22권4호
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• pp.999-1005
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• 2018

본 논문에서는 전력계통에서 정밀하고 변화에 수렴성이 빠른 탐색을 기반으로 하는 주파수 추정 기법을 제안하였다. 제안된 주파수 추정 알고리즘은 고분해능 스펙트럼의 기울기를 추정하여 스펙트럼의 peak 점을 탐색하는 구조를 적용하였다. 과도적으로 주파수 변화가 큰 경우에 기존 방법들의 단점인 수렴속도가 늦는 점을 보완 또는 개선하기 위한 방법으로 Context analysis를 통하여 Full-search 기법과 주파수 추정변수들을 적응적으로 적용하여 주파수 추정의 정밀도와 수렴속도를 향상시키고 대표적인 주파수 추정기법인 DFT(discrete Fourier transform) 방법, ECKF(extended complex Kalman filter), MV(minimum variable)방법들과 비교하여 수렴성과 정밀도가 우수함을 보였다.

• 인간식물환경학회지
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• 제24권1호
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• pp.107-117
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• 2021

Background and objective: The purpose of this study is to investigate the effect of a forest healing program in terms of depression, neuropsychological and physiological benefits for the elderly. Methods: For this purpose, we developed a forest therapy program for the elderly who are vulnerable to dementia and conducted a total of 11 sessions of forest therapy activities in a forest once a week. We measured the changes in depression, resting-state Electroencephalography(EEG) and heart rate variability (HRV) before and after the program. There were 60 subjects aged over 65 yesrs old. 30 subjects participated in the forest therapy program, and the other were in the control group. The Geriatric Depression Scale was used to measure the level of depression, neuroNicle FX2 (Laxtha, Korea) was used to measure the resting-state EEG, and photoplethymogram (ubpulse T1, Laxtha, Korea) was used to measure the HRV. Results: The results showed that the depression index of the experimental group improved with statistical significance after the program (experiment group = 3.267 decrease of the mean). In the EEG measurement, the alpha-peak frequency at rest (experimental group = 0.227 Hz increase of the mean) was improved (mean increase = 0.23 in the experimental group, p < .05). The high frequency of HRV, which represents the parasympathetic nerve activity of the body's autonomous response, was also significantly improved (mean increase = 0.396 in the experimental group, p < .05). Conclusion: The results suggest that the forest therapy program can reduce the cognitive, psychological and physical risk factors of dementia for the elderly at risk of cognitive decline. Therefore, forest therapy activities may be suitable for the prevention of dementia in the elderly.

• E2M - 전기 전자와 첨단 소재
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• 제7권3호
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• pp.187-199
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• 1994

In order to find an effect of structural changes due to variation of addition ratio of anhydride hardener and postcuring herat-treatments upon electrical properties of epoxy composites, the dielectric properties over a frequency range from 30[Hz] to l[MHz] were investigated in the temperature range of 20-180[.deg. C]. From the dielectric properties, the a peaks related with glass-transition phenomena of epoxy network appeared near 130[.deg. C], the conduction loss in high temperature region above 150[.deg. C] due to thermal dissociation of hardener started off with the low frequency side and the .betha. peak concerned with contribution of movable unreacted terminal epoxy groups and curing agents in the glass states concurred with the high-frequency side below 20[.deg. C]. And an effect of an hydride hardener upon structural changes and of postcuring heat treatments upon structural stability in epoxy composites would be explained through the estimation of the distribution of relaxation times and the activation energy for a .alpha. peak according to the WLF equations.

• 대한기계학회논문집
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• 제15권6호
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• pp.1919-1932
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• 1991

본 연구에서는 고강도 알루미늄 합금으로 제작된 평판보의 받음각(.alpha.)를 10˚ 에서 30˚까지 10˚씩 변화시킨 3가지의 모델에 대해, 각 모델의 Re$_{d}$수 변화에 대한 후류의 스펙트럼분석, 레이저 도플러 유속계(laser doppler velocimetry)를 이용 한 유동장 해석 및 평판보의 응답을 실험을 통해 조사, 분석하고 유동장과 측정이 용 이하지 않은 얇은 평판주위의 압력분포에 대한 전산해석을 수행함으로써 유동 여기진 동 구조의 규명을 시도하였다.다.

• Applied Science and Convergence Technology
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• 제26권2호
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• pp.26-29
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• 2017

Thin films of europium-doped yttrium oxide ($Y_2O_3$:Eu) were prepared on Si (100) substrates by using a radio frequency (RF) magnetron sputtering. After the deposition, the films were annealed at $1000^{\circ}C$ in an air ambient for 1 hour. X-ray diffraction analysis revealed that the $Y_2O_3$:Eu films had a polycrystalline cubic ${\alpha}-Y_2O_3$ structure. The as-deposited films showed no photoluminescence (PL), which was due to poor crystalline quality of the films. The crystallinity of the $Y_2O_3$:Eu films was significantly improved by annealing. The strong red PL emission was observed from the annealed $Y_2O_3$:Eu films and the highest intensity peak was centered at around 613 nm. This emission peak originated from the $^5D_0{\rightarrow}^7F_2$ transition of the trivalent Eu ions occupying the $C_2$ sites in the cubic ${\alpha}-Y_2O_3$ lattice. The broad PL excitation band was observed at wavelengths below 280 nm, which was attributed to the charge transfer transition of the trivalent Eu ion.

• 대한약리학회지
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• 제25권1호
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• pp.67-74
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• 1989

배뇨반사수축에 미치는 ${\alpha}$-수용체 및 내인성 catecholamine의 영향을 검토하기 위하여 체중 $190{\sim}220g$의 암컷흰쥐를 사용하여 부신절제 및 6-OHDA, yohimbine, prazosin 그리고 hexamethoium 처치시의 guanabenz에 의한 배뇨반사 수축을 비교 관찰하였든 바 그 결과는 다음과 같다. Guanabenz 3, 10 및 $30\;{\mu}g/kg$를 정맥주사하였을 때 용량증가에 따라 배뇨 반사수축의 크기와 횟수가 감소되었으며 $100\;{\mu}g/kg$투여시에는 완전히 억제되었다. 국소적용시에는 약하였고, 측뇌 실내투여시에는 거의 나타나지 아니하였다. 그리고 phenylephrine은 배뇨반사수축에 아무런 영향을 주지 않았다. 6-OHDA를 처치시 방광최고내압과 수축크기가 유의성있게 증가 되었으나, 부신절제나 yohimbine, prazosin, hexamethonium 투여로는 방광수축에 거의 변화가 없었다. Guanabenz의 배뇨반사수측의 크기와 횟수의 억제에 대한 용량반응곡선이 hexamethonium, 부신절제, 6-OHDA-, yohimbine 처치시 오른쪽으로 이동하였다. Guanabenz에 의한 억제작용이 yohimbine 처치>6-OHDA>부신절제>hexamethonium순으로 약화되었으나 prazosin처치로는 약화되지 아니하였다. 이상과 같은 결과로 미루어 guanabenz에 의한 배뇨만사수축의 억제작용은 ${\alpha}_1$-수용체와는 관계없이 ${\alpha}_2$-수용체흥분작용에 기인되며, 이 억제작용은 부신수질 및 교감신경말단에서 유리되는 catecholamines이 관여된 것으로 사료된다.