• Speech Sciences
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• v.14 no.3
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• pp.47-57
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• 2007

The aim of this study was to investigate the pitch and formant characteristics of vowels produced by monolingual and bilingual children. We collected sustained phonation of single vowels, /a/, /i/, /u/, from children aged 6 through 10 and compared their acoustic characteristics, fo, F1, F2. Results showed a significant difference between the groups in fo and F1 in the sustained phonation /a/, but not in F2. In the sustained phonation /i/, F2 revealed a significant difference but fo and F1 showed no significant difference. The F2 showed a significant difference in the sustained phonation /u/, but fo and F1 revealed no significant difference between the groups. It is needed to study further on the acoustic characteristics of bilingual children so that we can make a proper language intervention strategy for them.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.37-40
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• 2000

This paper has been studied on characteristics of organic light-emitting device with various cathode materials. These catode materials were Al：Li(5%), Al, Cu, CsF/Al. And in these devices, HTL(hole transfer layer) was TPD and EML(emitting layer) was Alq$\sub$3/. We studied the I-V characteristics for each device. And then, the turn-on voltage of device for Al-Li(5%), Al, Cu, CsF/Al cathode were 7, 9, 13, 3V respectively. So, the CsF/Al cathode is superior to other cathode materials for I-V characteristics.

• Research in Community and Public Health Nursing
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• v.13 no.1
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• pp.79-88
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• 2002

Purpose: The purpose of this study was to identify the indoor environment i.e. house type and age, ventilation method, use of bed & sofa, cockroach, ants, etc. on HDM (House dust mites), especially Der fI allergen. Method: Samples of dust from mattresses, pillows and the floor were collected by using a vacuum cleaner from April. 2000. The amount of Group I allergen(Der. fI) of HDM (house dust mites) were measured by two-site ELISA. Indoor Environmental characteristics were accessed by using questionnaires on 178 house wives living in the Seoul area. Results: The amount of HDM allergen (Der fI) was higher in sofa using house. There were higher concentrations of HDM allergen (Der fI) in sofas made from quilt material than for those that were made from leather. Homes that had pets like dogs living in them had higher concentrations of HDM allergen (Der fI) than without dogs. Conclusion: The photophobic mites thrive in dark. warm and humid environments; Items such as pillows. mattresses, box springs, blankets. carpets. and upholstered furniture should be considered ideal environments for the mite. Therefore, an indoor environmental control program should be carried out to avoid the HDM allergen.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.703-710
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• 2009

The spectral irradiance and underwater transmission characteristics of a combined high-luminance light-emitting diode (LED) lights have been studied to evaluate suitable light sources for fishing lamps of the next generation. The wavelengths at which the irradiance was maximum were changed from 473, 501, 525, and 465 nm for blue, peacock blue, green, and white LED light to 475, 504 and 528 nm for [$F_{WB}$], [$F_{PB}$] and [$F_{GB}$] combined LED lights, respectively. If the irradiance characteristics at 400-700 nm wavelengths are set as 100%, the irradiance rates at 450-499 nm and 500-549 nm were decreased from 82.4% and 56% for blue, peacock blue LED light to 60.0%, 38.5% for [$F_{WB}$], [$F_{WP}$] combined LED lights. The underwater transmission characteristics of the combined LED lights were superior in the order [$F_{WB}$], [$F_{BP}$], [$F_{GB}$] in optical water type I; [$F_{WB}$], [$F_{PB}$], [$F_{GP}$] in optical water type II-III; and [$F_{GP}$], [$F_{WP}$], [$F_{PB}$] in optical water type 1. Setting the 10m depth underwater transmission characteristics of the combined LED lights in optical water type I at 100%, the transmission of water types II, III and 1 drops to 29.5%, 8.0% and 2.2%. Based on the distribution of spectral irradiance and underwater transmission characteristics calculated in optical water types II-III, where was the jigging ground for fishing lamps, the [$F_{WB}]$ and [$F_{GP}$] combined LED lights can be used as a suitable light sources for fishing lamps of the next generation.

• Phonetics and Speech Sciences
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• v.9 no.1
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• pp.49-53
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• 2017

Formant frequencies depend on the position of tongue, the shape of lips, and larynx. In the auditory system, the external ear canal is an open-end resonator, which can modify the voice characteristics. This study investigates the effect of the real ear on formant frequencies. Fifteen subjects ranging from 22 to 30 years of age participated in the study. This study employed three corner vowels: the low central vowel /a/, the high front vowel /i/, and the high back vowel /u/. For this study, the voice of a well-educated undergraduate who majored in speech-language pathology, was recorded with a high performance condenser microphone placed in the upper pinna and in the ear canal. Paired t-test showed that there were significant difference in the formant frequencies of F1, F2, F3, and F4 between the free field and the real ear. For /a/, all formant frequencies decreased significantly in the real ear. For /i/, F2 increased and F3 and F4 decreased. For /u/, F1 and F2 increased, but F3 and F4 decreased. It seems that these voice modifications in the real ear contribute to interpreting voice quality and understanding speech, timbre, and individual characteristics, which are influenced by the shape of the outer ear and external ear canal in such a way that formant frequencies become centralized in the vowel space.

• Journal of Biomedical Engineering Research
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• v.18 no.3
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• pp.267-272
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• 1997

he scintillation detector having $BaF^2$ crystal with 3.6cm dia${\times}$2.0 cm thick was provided. The energy and timing characteristics were measured and compared with NaI(Tl) scintillation detectors, which widely used in unclear medicine. In order to measure the energy spectrum, the radioactive sources used were $^{22}Na,\;^{54}Mn,\;^{57}Co,\;^{137}Cs$ and the source to detector distance was 7cm. For the timing characteristic, NaI(Tl)(1" ${\times}$ 1")-$BaF^2$ and NaI(Tl)(3" ${\times}$ 3")-$BaF^2$ timing coincidence systems were prepared and the used source was $^{22}Na$ emitting 511keV annihilation photons. For the 511keV gamma-ray emitted from $^{22}Na$, It was revealed that the timing response of the $BaF^2$ detector was faster than NaI(Tl)(1" ${\times}$ 1") and NaI(Tl)(3" ${\times}$ 3") detector used in this experimental investigation. The energy characteristics of the $BaF^2$ detector had a good values for about 500keV energy range.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.6
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• pp.442-450
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• 1999

In this paper, we have fabricated Langmuir-Blodgett(LB) films by LB technique and evaluated the deposited status of LB films by UV-vis absorbance. It was found thatthe thickness of LB films per a layer are $27~30[{\AA}]$ by ellipsometry. The responeses between LB films and organic gases were investigated using by I-V characteristics of LB films and F-R diagram of quartz crystal. The response orders between LB films and organic gases observed by I-V characteristics were as following ; chloroform, methanol, acetone and ethanol in the order of their short chain length. The response mechanism between LB films and organic gases observed by F-R diagram of quartz crystal could be modeled on adsorption at surface, penetration, desorption at surface and inside.

• Applied Biological Chemistry
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• v.29 no.2
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• pp.175-181
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• 1986

Eightyseven strains of indigenous Rhizobia were isolated from the nodule of soybean cultivar, Danyup, cultivated in four different soils sampled from continuously soybean cultivated and newly reclaimed fields. The strains were grouped into Bradyrhizobium japanicum (slow-grower:55 strains) and Rhizobium fredii (fast-grower: 32 strains). The both groups could be divided into two sub-groups according to the denitrification characteristics, that is, denitrifying fast-grower (F-I), nitrate respiring fast-grower (F-II), denitrifying slow-grower (S-I). and nitrate respiring slow-grower (S-II). Among the 87 isolates, F-I, F-II, S-I and S-II sub-groups were 10, 22, 48 and 7 strains, respectively. The one-and two-dimensional polyacrylamide gel electrophoretic pattern of the four sub-groups were compared and discernible difference was observed between fast and slow-grower, but the difference was not discernible between subgroups within the same growth rate group.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.451-465
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• 2008

The DC over current relay(76i) and the DC under voltage relay(mid-point relay, 80A) used mainly with DC protective relay system of DC electric railway in Korea, But the DC fault selective relay(50F) is applying to recently mainly. In this study, simulation to compare 76i/80A and 50F in the methods of protection and the operational characteristics were executed through verifying a calculation of short circuit current and using PSCAD/EMTDC transition program. As a result of this study, it was proved that while 80A runs in relation to the scale of fault resistance, 50F runs regardless of the scale of fault resistance or the length of rail.

• Transactions on Electrical and Electronic Materials
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• v.8 no.4
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• pp.174-177
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• 2007

We fabricated organic field-effect transistors (OFETs) based a fluorinated copper phthalocyanine ($F_{16}CuPC$) and copper phthalocyanine (CuPc) as an active layer. And we observed the surface morphology of the $F_{16}CuPC$ thin film. The $F_{16}CuPC$ thin film thickness was 40 nm, and the channel length was $50{\mu}m$, channel width was 3 mm. And we also fabricated the $F_{16}CuPc/CuPc$ double layer FET and with different $F_{16}CuPc$ film thickness devices. We observed the typical current-voltage (I-V) characteristics and capacitance-voltage (C-V) in $F_{16}CuPc$ FET and we calculated the effective mobility. From the double layer FET devices, we observed the higher drain current more than single layer FET devices.