• Phonetics and Speech Sciences
• /
• v.4 no.3
• /
• pp.43-49
• /
• 2012

This paper describes the categorical effects of pitch accent contrasts in a mimicry task. It focuses, specifically, on examining how fundamental frequency (f0) variation reflects phonological contrasts from speakers of two distinct varieties of Korean (i.e., North Kyungsang and South Cholla). The results showed that, in a mimicry task using synthetic speech continua, there was a categorical effect in f0 peak timing for North Kyungsang speakers, but the timing of f0 peaks and valleys in the responses of South Cholla speakers was more variable, presenting a gradient or non-categorical effect. Evidence of categorical effects was represented as the shift of f0 peak times along an acoustic continuum for North Kyungsang speakers. The range for the shift of f0 valley times was much narrower, compared to that of f0 peak times. The degree of a shift near the middle of the continuum showed variability across individual mimicry responses. However, the categorical structure in mimicry responses regarding the clustering of f0 peak points was more significant for North Kyungsang speakers than for South Cholla speakers. Additionally, the finding of the current study implies that the location of f0 peak times depends on individuals' imitative (or cognitive) abilities.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.3
• /
• pp.66-74
• /
• 1999

InAlGaAs/InGaAs HBTs with the various emitter junction gradings(xf=0.0-1.0) and the modified collector structures (collector- I;n-p-n, collector-II;i-p-n) are simulated and analyzed by HMC (Hybrid Monte Carlo) method in order to find an optimum structure for the shortest transit time. A minimum base transit time($ au$b) of 0.21ps was obtainsed for HBT with the grading layer, which is parabolically graded from $x_f$=1.0 and xf=0.5 at the emitter-base interface. The minimum collector transit time($\tau$c) of 0.31ps was found when the collector was modified by inserting p-p-n layers, because p layer makes it possible to relax the electric field in the i-type collector layer, confining the electrons in the $\Gamma$-valley during transporting across the collector. Thus InAlGaAs/InGaAs HBT in combination with the emitter grading($x_f$=0.5) and the modified collector-III showed the transit times of 0.87 psec and the cut-off frequency (f$\tau$) of 183 GHz.

• Journal of Broadcast Engineering
• /
• v.26 no.4
• /
• pp.409-418
• /
• 2021

Conformal coating is a technology that protects PCB(Printed Circuit Board) and minimizes PCB failures. Since the defects in the coating are linked to failure of the PCB, the coating surface is examined for air bubbles to satisfy the successful conditions of the conformal coating. In this paper, we propose an algorithm for detecting problematic bubbles in high-risk groups by applying image signal processing. The algorithm consists of finding candidates for problematic bubbles and verifying candidates. Bubbles do not appear in visible light images, but can be visually distinguished from UV(Ultra Violet) light sources. In particular the center of the problematic bubble is dark in brightness and the border is high in brightness. In the paper, these brightness characteristics are called valley and mountain features, and the areas where both characteristics appear at the same time are candidates for problematic bubbles. However, it is necessary to verify candidates because there may be candidates who are not bubbles. In the candidate verification phase, we used convolutional neural network models, and ResNet performed best compared to other models. The algorithms presented in this paper showed the performance of precision 0.805, recall 0.763, and f1-score 0.767, and these results show sufficient potential for bubble test automation.

• Korean Journal of Environment and Ecology
• /
• v.23 no.5
• /
• pp.471-484
• /
• 2009

This study was carried out to classify vegetation structure on the deciduous forest at Namdeogyu area in Deogyusan National Park from May 2007 to September 2008 using the gradient analyses and phytosociological method. The vegetation was classified into Quercus mongolica community(Typical subcommunity, Rhododendron sehlippenbaehii-Q. mongolica subcommunity, Carex lanceolata-Q. mongolica subcommunity), Q. Serrata community(Typical subcommunity, Q. variabilis -Q. serrata subcommunity, Carpinus laxiflora - Q. serrata subcommunity), C. laxiflora community, Fraxinus mandshurica community and Corn us controversa community. Ecological characteristics such as species composition, layer structure, vegetation ratio, and the distribution of individual trees by DBH(diameter at breast height) were significantly different among communities. The order of important value of the forest community with DBH 2cm above plants was Q. mongolica(67.8), F. mandshurica(44.8), Q. serrata(27.5), Acer pseudo-sieboldianum(17.0), C. controversa(l5.9), F. sieboldiana(l1.5), R. schlippenbachii(11.0), C. cordata(11.0), Styrax obassia(10.9), Magnolia sieboldii(10.4) and C. laxiflora(9.8). Distribution of DBH of Q. mongolica had a formality distribution, suggesting a continuous domination of these species over the other species for the time being. In contrast, F. mandshurica appeared limited to the valley of the sheet and a higher frequency of young individuals, suggesting a continuous domination of these species the development of a climax forest terrain. Q. serrata had a higher frequency of young individuals and middle individuals, suggesting a continuous domination of these species over the other species for the time being in contrast. This study examined the correlation between each community and the environment according to DCCA ordination. The Q. mongolica community predominated in the highest elevation habitats which had many C.E.C and T-N. F. mandshurica community predominated in the highest elevation habitats which had many Moisture and EX-Cation. The Q. serrata community and C. laxiflora community mainly occurred in the low elevation habitats which had few C.E.C and T-N. The C. controversa community appeared on the park in the middle habitats.