• 전자공학회논문지 IE
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• 제43권4호
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• pp.1-7
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• 2006

본 연구에서는 정공 저지층이 없는 Type I과 정공 저지층으로 두께가 30${\AA}$인 BCP와 BAlq 재료를 사용한 Type II의 청색 유기발광소자를 제작하였다. ITO 박막 위에 $N_2$ 가스에서 플라즈마 출력이 200 W 일 때, 5.02 eV의 일함수 값을 갖는 ITO를 얻을 수 있었다. Type I 소자는 ITO/2-TNATA/$\alpha$-NPD/DPVBi/$Alq_3$/LiF/Al:Li 구조로 되어 있으며, Type II 소자는 ITO/2-TNATA/$\alpha$-NPD/DPVBi/정공 저지층/$Alq_3$/LiF/Al:Li 구조로 되어 있다. Type I과 Type II 소자의 특성을 비교하였다 제작된 소자 중에서 특성이 가장 우수한 것은 정공 저지층으로 두께가 30${\AA}$인 BAlq 재료를 사용한 Type II 소자이었고, 인가전압 10 V 에서 소자의 전류밀도는 226.75$mA/cm^2$, 휘도는 10,310$cd/cm^2$, 발광효율은 4.55 cd/A, 전력효율은 1.43 lm/W 이었다. EL 스펙트럼의 최대 발광 파장은 456 nm 반치폭은 57 nm 이었고 색좌표값은 x = 0.1438, y = 0.1580 로 NTSC 색좌표 Deep blue영역(x = 014, y = 0.08)에 근접한 순수한 청색에 가까운 값을 얻었다.

• 대한후두음성언어의학회지
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• 제21권1호
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• pp.48-53
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• 2010

Backgraound and Objectives : The voice change can occur in acute epiglottitis or peritonsillar abscess, and the labelings of both changes as a "muffled voice" or "hot potato voice", The aim of this study was to investigate the difference of changes in acoustic feature of voice before and after treatment in patients with acute epiglottitis or peritonsillar abscess. Subjects and Method: 13 patients with acute epiglottitis and 12 patients with peritonsillar abscess were enrolled in the study. Acoustic analysis on sustained Korean vowels /${\alpha}$/, /u/ and /i/ were performed before and after treatment. Results: In patients with acute epiglottitis, the first formant frequency (F1) of /${\alpha}$/ was increased, and the second frequency (F2) of /i/ was decreased. In patients with peritonsillar abscess, F1 and F2 of /${\alpha}$/ were decreased. F1 of /i/ and /u/ were increased, while F2 were decreased. Conclusion : The anatomical and functional changes of oropharynx and larynx by acute epiglottitis and peritonsillar abscess can cause different change in resonance and speech quality. We suggest that these changes could be the cause of 'muffled vocie' in patients of acute epiglottitis or peritonsillar abscess, but different characteristics of phonation in each disease should be distinguished.

• 대한전자공학회논문지SD
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• 제48권9호
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• pp.1-5
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• 2011

본 논문에서는 AlGaN/GaN HEMT의 DC 및 RF 특성을 최적화 하기위해서 2차원 소자 시뮬레이터를 이용하여 연구를 진행하였다. 먼저, AlGaN층의 두께, Al mole fraction 의 변화에 따른 2차원 전자가스 채널의 농도변화가 생기는 현상을 바탕으로 DC특성을 분석하였다. 다음 게이트, 소스, 드레인 전극의 크기와 위치 변화에 따른 RF 특성을 분석하였다. 그 결과 Al mole fraction이 0.2몰에서 0.45몰로 증가할수록 전달이득(transconductance, $g_m$) 과 I-V 특성이 향상됨을 확인하였다. 한편 AlGaN층의 두께가 10nm에서 50nm로 증가할수록 I-V특성은 향상되지만 $g_m$은 감소하는것을 확인하였다. RF 특성에서는 게이트 길이가 가장 큰 영향을 미치며 그 길이가 짧을수록 RF특성이 향상되는 것을 확인하였다.

• Journal of Plant Biology
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• 제38권2호
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• pp.165-171
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• 1995

Plants of G. furcata were divided into four variant populations. The habit characteristics, external and internal morphology were analysed quantitatively in order to clarify their morphological variation. Among four variant populations, type I(typical G. furcata type) and type II(G. furcata f. intricata type) may be influenced by the time when the develop from the crustose basal discs and the tidal level. Type III is the immature plants, and type IV (G. furcata f. coliformis type) is a G. furcata population in late spring after the luxuriant season. For the reason, the formas of G. furcata f. intricata and f. coliformis are no more valid in Gloiopeltis furcata.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2007년도 한국음성과학회 공동학술대회 발표논문집
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• pp.193-196
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• 2007

The purpose of this paper is to find boundary tone's characteristics in Korean emotion speeches. I mainly focus on investigating patterns and f0 values of boundary tones and f0 values in utterance final phrases.

• 대한기계학회논문집B
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• 제24권8호
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• pp.1038-1045
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• 2000

An experimental study was carried out to delineate the flow characteristics in a closed countescurrent two-phase thermo syphon with concentric tubes. This is to be installed in the HANARO research reactor as a part of a Cold Neutron Source(CNS). In the present investigation, experiments ata room temperature with Freon-II3 as a moderator were performed. Results show that, based on the magnitude of pressure fluctuation, the flow regimes could be divided into 4 distinct ones in the ($V_f,\;Q_i$) plane, where $V_f$ represents the volume of the charged liquid and $Q_i$ the heat load: a stable flow regime, an oscillatory flow regime, a restablized flow regime and a dryout flow regime. For $V_f$>2.5l, the flow is stable at low $Q_i$. However, as $Q_i$ increases, the flow becomes oscillatory and finally restablizes As $V_f$ increases, the oscillation amplitude decreases, reaching to the restablized flow region at low $Q_i$, and the liquid level in the moderator cell remains high. In the oscillatory flow regimes, for a fixed VI; the oscillating period of time varies with $Q_i$, having a minimum value at a certain value of $Q_i$. The heat load, where the oscillating period of time is minimum, decreases as $V_f$ increases.

• 한국의류학회지
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• 제24권7호
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• pp.1081-1087
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• 2000

Gromwell colorants were extracted with methanol and dried. Four fractions were obtained by silica gel adsorption column chromatography using step-wise elution method. Relative ratio of four fraction is 1.00:0.07:0.22:0.30(Fl:F2:F3:F4) and gromwell colorants mainly consist of Fl, F3 and F4. IR analysis shows that each fraction has similar structure. Main component of gromwell extracts is acetyl derivative of naphthoquinone, and the rest are isobutyl derivative and isovaleryl derivative etc., in order. Gromwell colorants exhibit relatively good affinity to protein and polyamide fibers, but low affinity to cellulose and regenerated cellulose fibers.

• Journal of Plant Biology
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• 제29권1호
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• pp.19-40
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• 1986

A study on the species description, enumeration and interspecific relationships of genus Filipendula was undertaken for four Korean and two Japanese species. The use of scanning electron miroscope(SEM) has made possible a detailed study of foliar trichomes, pollen grains and fruit surface features. A new method for the preparation of SEM samples was developed in this study. Filipendula glaberrima, F. formosa, and F. korean were reliable endemic species. Among them, F. glaberrima shares many characteristics with F. formosa. F. gloaberrima can be divided into tow types based on leaf, seed, flower and pollen characters. Type I is characterized by ciliated fruits, many branched vascular bundles on the petal, dense trichomes on the leaf vein of abaxial surface, and many foveolate pollen surface. Type II possesses glabrous fruits, a few vascular bundles on the petal, rare trichomes on the leaf vein and a few foveolate pollen surface. The significant taxonomic characteristics in the classification of genus Filipendula are their lengths of fruit stalks, the densities of marginal trichomes of fruits, and textures of stipules.

• 말소리와 음성과학
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• 제2권4호
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• pp.229-238
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• 2010

This study investigates the differences in acoustic parameters in vowel space across hearing loss, gender and vowels. The parameters include F1, F2, Euclidean Distance between vowels, and vowel triangular area comprised of /i/, /a/ and /u/. For this study, 20 hearing-impaired and normal hearing adults as a control group were asked to read 7 Korean vowels (/a, $\wedge$, o, u, w, i, $\varepsilon$/). Subjects' readings were recorded by NasalView and analyzed by Praat. Results showed that F1 were significantly higher in the hearing impaired group than in the normal hearing group, higher in the female group than in male group, and higher in low vowels than in high vowels. And the means of F2 was significantly higher in the hearing impaired group than in normal hearing group, higher in high vowels than in low vowels, and there was no difference between male and female group. Secondly, Euclidean distance between vowels was significantly shorter in the hearing-impaired group than in the normal group. Finally, acoustic vowel space area was significantly smaller in the hearing-impaired group than in the normal hearing group. The hearing-impaired group showed that front vowels tended to be backed and back vowels to be fronted.

• 말소리와 음성과학
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• 제5권4호
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• pp.71-78
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• 2013

The purpose of this study was to compare the acoustic voice outcomes of children with cochlear implant to those of children with normal hearing. Participants were 41 children using unilateral cochlear implant (18 males and 23 females), and children with normal hearing from the same age and sex. Mean age of implantation was approximately 3 years old, mean duration of implant use was 4 years in CI group. Acoustic analyses were performed using MDVP of CSL. Speech samples were 3 sustained vowels, /a, i, u/. 9 parameters (F0, Fhi, Flo, Jitter, Shimmer, vF0, vAm, NHR, and SPI) were analyzed. Children with CI did not show the significant differences in those parameters after the vowel /a/ phonation. Meanwhile, there were significantly different results in F0, Fhi, vF0, and SPI after /i, u/ phonation. These results revealed that differences of voice characteristics in children with CI compare to children with NH persist regarding vowel context. It suggests that high vowels would recommend as speech samples for acoustic evaluation. Futhermore perceptual analysis and speech therapy for phonation control would be necessary for children with CI.