• Phonetics and Speech Sciences
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• v.9 no.3
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• pp.25-32
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• 2017

Besides their effect on the f0 contour of the following vowel, Korean stops are undergoing a sound change in which a partial or complete consonantal merger on voice onset time (VOT) is taking place between aspirated and lax stops. Many previous studies on sound change have mainly focused on group-normative effects, that is, effects that are representative of the population as a whole. Few systematic quantitative studies of change in adult individuals have been carried out. The current study examines whether the sound change holds for individual speakers. It focuses on inter-speaker and intra-speaker variability on sound change in contemporary Korean. Speech data were collected for thirteen Seoul Korean speakers studying abroad in America. In order to minimize the possible effects of speech production, socio-phonetic factors such as age, gender, dialect, speech rate, and L2 exposure period were controlled when recruiting participants. The results showed that, for nine out of thirteen speakers, the consonantal merger is taking place between the aspirated and lax stop in terms of VOT. There were also intra-speaker variations on the merger in three aspects: First, is the consonantal (VOT) merger between the two stops is in progress or not? Second, are VOTs for aspirated stops getting shorter or not (i.e., the aspirated-shortening process)? Third, are VOTs for lax stops getting longer or not (i.e., the lax-lengthening process)? The results of remarkable inter-speaker and intra-speaker variability indicate a synchronous speech sound change of the stop system in contemporary Korean. Some speakers are early adopters or active propagators of sound change whereas others are not. Further study is necessary to see whether the inter-speaker differences exceed intra-speaker differences in sound change.

• Phonetics and Speech Sciences
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• v.13 no.3
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• pp.39-51
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• 2021

Based on spontaneous speech data collected in 2020, this study examined the production and perception of Korean lenis, aspirated, and fortis stops. Unlike the controlled experiments of previous studies, lenis and aspirated stops of males in their 30s were not distinguished by voice onset time (VOT) in spontaneous speech. Perceptual experiments were conducted on young females, the leaders of language change. F0 was found to serve as the primary cue for the perception of lenis stops, and then VOT distinguished the aspirated and fortis stops. The fact that the sounds were always perceived as lenis stops when F0 was low, irrespective of whether VOT was short or long, showed that F0 plays an absolute role in the perception of lenis stops. However, in some cases the aspirated and lenis stops were distinguished only by VOT, which does not happen in production. In terms of sound change, disagreement between production and perception systems occurs when sound change is in progress. In particular, when production change precedes perception change, it indicates that the sound change is in its latter stages. Young females still maintain the previous system in perception because the distinction of lenis and aspirated stops by VOT was valid in their parents' generation. In other words, VOT is still used for perception to communicate with other groups.

• Phonetics and Speech Sciences
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• v.15 no.3
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• pp.45-52
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• 2023

Previous studies have established a role for cognitive differences in explaining variability in speech processing across individuals. In the case of perceptual cue weighting in the context of a sound change, studies have produced conflicting results regarding the relationship between executive function and the use of redundant cues. The current study aimed to explore this relationship in acoustic cue weighting during speech production. Forty-one Korean-speaking children read a list of stop-initial words and completed two tests that assess executive function, i.e., Dimensional Change Card Sorting (DCCS) and digit n-back. Voice onset time (VOT) and fundamental frequency (F0) were measured in each word, and analyses were carried out to determine the extent to which children's executive function predicted their use of both informative and less informative cues to the three pairs comprising the Korean three-way stop laryngeal contrast. No evidence was found for a relationship between cognitive ability and acoustic cue weighting in production, which is at odds with previous, albeit conflicting, results for speech perception. While this result may be due to the lack of task demands in the production task used here, it nevertheless expands the empirical ground upon which future work in this area may proceed.

• Phonetics and Speech Sciences
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• v.5 no.4
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• pp.171-184
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• 2013

This study investigated the devoicing rate of Japanese high vowels, focusing on regional and generational differences by acoustically analyzing vowels from two large speech databases. The first speech database used in this study was collected between 1986 and 1988 from 41 areas (prefectures) which included 607 participants (299 high school students and 308 their grandparents). The second was taken from a 2006-2007 collection from seven areas as a follow-up investigation to the first database consisting of 463 participants ranging in age from 8-90 year olds. The results revealed there is a generational as well as regional difference in the devoicing rate in almost all areas. Based on those results, a new distribution map reflecting a current devoicing rate of the younger generation was presented. Furthermore, by comparing the two data sets, this study confirmed age difference in the devoicing rate is not age-grading but a sound change in progress. This study discusses the social factors for changes in the devoicing rate of some areas and then applies the devoicing rate of five areas to an S-curve model to predict the future devoicing rate.

• Phonetics and Speech Sciences
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• v.10 no.3
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• pp.1-8
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• 2018

The vowel /o/ in Seoul Korean has been undergoing a sound change by altering the acoustic weighting of F2 and F1. Studies documented that this on-going change redefined the nature of a /o/-/u/ contrast as F2 differences rather than as F1 differences. The current study examined two cognitive factors namely executive function capacity (EF) and autistic traits, in terms of their roles in explaining who in speech community would adapt new acoustic forms of the target vowels, and who would retain the old forms. The participants, 55 college students speaking Seoul Korean, produced /o/ and /u/ vowels in isolated words; and completed three EF tasks (Digit N-Back, Stroop, and Trail-Making Task), and an Autism screening questionnaire. The relationships between speakers' cognitive task scores and their utilizations of F1 and F2 were analyzed using a series of correlation tests. Results yielded a meaningful relationship in participants' EF scores interacting with gender. Among the females, speakers with higher EF scores were better at retaining F1, which is a less informative cue for females since they utilized F2 more than they did F1 in realizing /o/ and /u/. In contrast, better EF control among male speakers was associated with more use of the new cue (F2) where males still utilized F1 as much as F2 in the production of /o/ and /u/ vowels. Taken together, individual differences in acoustic realization can be explained by individuals' cognitive abilities, and their progress in the sound change further predicts that cognitive ability influences the utilization of acoustic information which is non-primary to the speaker.

• Journal of Oral Medicine and Pain
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• v.22 no.1
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• pp.95-109
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• 1997

The purpose of this research is to investigate the influence on mandibular movements and TMJ sounds with changes of head and neck posture. For the research, twenty patients who had complained of TMJ sounds without any other symptoms of cranio-mandibular disorders, were selected as subjects for measurements of TMJ sounds, and radiographs on transcranial view of TMJ were taken on ten of the subjects. From NHP, UHP, DHP and FHP, aspects of mandibular movement and TMJ sound were investigated from each posture. Aspects of mandibular movement and TMJ sound were observed by measuring total vibration energy(Integral), peak amplitude, maximum amound of mouth opening, and TMJ sound-emitting point using Sonopak for windows (version 1.33) and Bio-EGN(Bioresearch Inc. WI. U.S.A.). Head and neck movement-measuring instrument, CROM(perfomance attainment Inc. U.S.A.) was to maintain even head posture. Degrees of inclination of UHP and DHP were determined at 30' and distance of FHP was 4cm. The results obtained were as follows. 1. Total vibration energy and peak amplitude of TMJ sounds were decreased more on UHP and on UHP and increased more on DHP and FHP than that on NHP. 2. At the maximum mouth opening, distance of TMJ sound-emitting point were decreased more on UHP and increased more on DHP and FHP than that on NHP. 3. The amounts of the maximum mouth opening were increased more on UHP and decreased more on DHP and FHP than that on NHP. 4. For the changes of the head posture with mouth opening observed in radiograph, condylar head was positioned more lower-anteriorly on UHP, and more upper-posteriorly on DHP and FHP than that on NHP. From the results obtained as above, considering positive influence of the change of head and neck posture, avoiding down-head and forward-head posture, and recommending upper- head posture can prevent the progress of temporomandibular disorder and lead to successful treatment for the patients with temporomandibular joint sounds.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.2
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• pp.136-142
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• 2006

Temporomandibular joint(TMJ) disorders have characteristic clinical findings such as pain, joint sound, and abnormal jaw function. With the rapid progress in TMJ imaging techniques, magnetic resonance imaging(MRI) especially provides the clinician and researcher with the ability to evaluate TMJ disorders(effusion, anterior disk displacement) and the hard and soft tissue of the TMJ. In order to manage the internal derangement of TMJ such as anterior disk displacement, the so-called appliance therapy is commonly used. This technique became the treatment of choice before surgical intervention by many practitioners. The purpose of the present study was to evaluate and determine the efficacy of anterior repositioning splint by means of the change of the position of the disk through pre- and post-treatment MRI. MRI and clinical symptom were carefully recorded in TMJ disorder patients. The relationship between TMJ symptoms such as pain, clicking sound, and disk displacement and effusion in MRI were analyzed. Then, splint therapy was applied for 3 months according to our protocol; at day 1, patients should wear 24 hours, in order to accomodate the splint and then, wearing time is reduced to 12 hours per day for one month. During next 2 months, it is tapered to 8 hours per day according to the evaluation of the clinical symptoms. Post-treatment MRI was obtained after 3 month protocol. This treatment strategy improved the clinical symptoms of TMJ disorder, and effusion and articular disk position showed a significant change. In conclusion, a treatment modality using an anterior repositioning splint therapy is an appropriate method for temporomandibular disorder patients.

• The Korean Journal of Mycology
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• v.21 no.2
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• pp.106-111
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• 1993

Pectolytic enzymes were extracted in apple fruits rotted by Botryosphaeria dothidea, and their activities and change of pectic substances were investigated. Exo-polygalacturonase(exo-PG), exo-polymethylgalacturonase(exe-PMG), polygalacturonate-trans-eliminase(PGTE) and pectin-methyl-trans-eliminase(PMTE) were produced by the pathogen. Activities of exo-PG and exe-PMG extracted from rotten apple fruits were high to 21.15 and 24.65 units/mg protein in specific activity at seven days after inoculation, respectively. Activities of PGTE and PMTE showed 5.60 and 7.90 units/mg protein, respectively, but they were lower than those of the exo-type enzymes. Water-soluble and versene-soluble pectins were 11.50 mg/100 mg-AIS and 7.31 mg/100 mg-AIS at 14 days after inoculation, namely, they were increased by 4.23 and 2.16 mg/100 mg-AIS over those of sound apples, respectively. Total soluble pectic substances of rotten apple were 72.4% of total pectic substances and it was higher by 24.8% than sound apple. Insoluble pectic substance was notably decreased from 15.32 to 7.16 mg/100 mg-AIS according to progress of decay while total pectic substances were not changed remarkably.

• Science of Emotion and Sensibility
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• v.23 no.4
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• pp.105-116
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• 2020

The purpose of this study is to progress the limitations and disadvantages of existing safety clothing by applying high technology to current safety clothing that is produced and distributed only with fluorescent fabrics and retroreflective materials. Therefore, the industrial suspender-type safety belt and engineering technology are introduced, designed, and fabricated to help save a life in an emergency. First, the suspender-type safety belt to be developed is designed to emit light by LED attached to the film, and the body of the belt-wearer is recognized from a distance through retroreflection from the flashing LED. It aims to support people's safety by preventing accidents during roadside work, rescue activities, and sports activities at night. Second, with the development of advanced devices when the user is in an unconscious state due to distress or falls into an unconscious state due to distress or accident, the tilt sensor of the control unit attached to the belt automatically detects the angle of the human body and generates light and sound. It is intended to further enhance the utilization by mounting a sensing and signaling device that generates a distress signal and shaping it in the form of a belt attached to a vest that can be easily detached from the outside of the garment. When the wearer falls due to an accident, the tilt sensor of this belt detects the angle change and then the controller generates a high-frequency sound and repeated LED blinking signals at the same time. In the case of conventional safety vests, it is almost impossible to detect that the person is wearing a vest when there is no ambient light, but in case of the safety belts in this study, the sound and light signals of the safety belt enable us to find the wearer within 100 meters even when there is no ambient light.

• Journal of Broadcast Engineering
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• v.17 no.5
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• pp.827-837
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• 2012

As broadcasting environments change rapidly to digital, user requirements for next-generation broadcasting service which surpass current HDTV service become bigger and bigger. The next-generation broadcasting service progress from 2D to 3D, from HD to UHD and from 5.1ch audio to more than 10ch audio for high quality realistic broadcasting service. In this paper, we propose 10.2ch based multichannel audio reproduction system for UHDTV. The 10.2ch-based audio reproduction system add two side loudspeakers to enhance the surround sound localization effect and add two height and one ceiling loudspeakers to enhance the elevation localization effect. To evaluate the proposed system, we used APM(Auditory Process Model) for objective localization test and conducted subjective localization test. As a result of objective/subjective localization test, the proposed system shows the statistically same performance compare with 22.2ch audio system and shows the significantly better performance compared with 5.1ch audio system.