• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.2
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• pp.50-58
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• 1983

In this paper, a field trial of the Korean-made optical fiber communication system is described. This system was installed between Gu-Ro and Ann-Yang telephone offices on November 1981, and carries a 44.7Mb/s NRZ signal(672 voice channel equivalent). For this trial, optical fiber cable, optical terminal equipment, optical repeater, fusion splicer and measurement equipment have been developed. Employing graded index optical fiber at a wave length of $0.85\;\mu\textrm{m}$, average optical attenuation and splicing losses of 3.6 dB/km and 0.4 dB, resectively, were realized. With link margins of 8~20dB and bit error rate of less than $10^{-10}$, this system has been carrying live traffic between Seoul and Ann Yang telephone offices.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.7-10
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• 2000

본 논문은 이동통신상에서 송신측의 송신 채널 에러정보를 수신측에서 송신측으로 전달하는 음성패킷을 이용하여 송신측에 알려주어 압축과정에 이용하게 할 수 있는 방법을 제안한다. ACELP(Algebraic CELP)구조 방식을 가지고 있는 음성압축기들 중 G.729을 사용하며 음성 패킷정보 중 Pitch Delay와 Fixed Codebook를 이용하여 전송음성 패킷안에 상대방의 송신 채널정보를 싣는다. 수신측에서 받은 패킷이 Erasure로 판단되었을 때 패킷정보들 중 Fixed Codebook Index를 만들게 되는 4개의 Optimal 펄스 중 2개의 펄스만 사용하며 나머지 2개의 펄스는 약속된 임의의 위치에 위치시킨 후 송신측에 전송시킨다. 상대방에서 약속에 맞는 위치의 펄스를 보내왔을 때를 체크함으로써 자신의 송신채널 상태를 알 수 있게 된다 송신채널에$5\%$ Erasure 채널 에러가 발생했을 때 채널정보를 가진 패킷의 음질은 약 0.1dB 정도 떨어지게 된다. 하지만 음성압축 전송 시 송신채널의 정보를 이용하여 무선채널에러에 강하게 할 수 있다.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.24 no.2
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• pp.112-117
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• 2013

Background and Objectives : This study aimed to determine the clinical effect of $Artecoll^{(R)}$ injection laryngoplasty for patients with vocal atrophy and mild sulcus vocalis. Materials and Method : Forty-one patients with vocal atrophy and/or mild sulcus vocalis received transcutaneous $Artecoll^{(R)}$ injection into the vocal folds under local anesthesia. Subjective evaluations including voice handicap index (VHI) and perceptual grading with Grade, Roughness, Breathiness, Asthenia, Strain (GRBAS) scales and objective evaluations including jitter, shimmer, noise-to-harmonic ratio (NHR), speaking fundamental frequency (SFF) and maximum phonation time (MPT) were evaluated before and 3 months after the injection. Results : VHI and Grade, Breathiness and Strain scales in GRBAS showed significant improvement 3 months after injection. SFF and MPT also significantly improved after the injection ; MPT increased and SFF in male patients decreased. Conclusion : Injection laryngoplasty with $Artecoll^{(R)}$ is an effective method for correcting the glottal insufficiency and improving voice quality in patients with vocal atrophy and/or mild sulcus.

• Phonetics and Speech Sciences
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• v.4 no.2
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• pp.61-70
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• 2012

The current study observes the durational interaction of tautosyllabic consonants and vowels in the word-initial position of English and Korean child-directed speech (CDS). The effect of phonological laryngeal contrasts in stops on the following vowel duration, and the effect of the intrinsic vowel duration on the release duration of preceding stops in addition to the acoustic realization of the contrastive segments are explored in different prosodic contexts - phrase-initial/medial, focal accented/non-focused - in a marked speech style of CDS. A trade-off relationship between Voice Onset Time (VOT), as consonant release duration, and voicing phonation time, as vowel duration, reported from adult-to-adult speech, and patterns of durational variability are investigated in CDS of two languages with different linguistic rhythms, under systematically controlled prosodic contexts. Speech data were collected from four native English mothers and four native Korean mothers who were talking to their one-word staged infants. In addition to the acoustic measurements, the transformed delta measure is employed as a variability index of individual tokens. Results confirm the durational correlation between prevocalic consonants and following vowels. The interaction is revealed in a compensatory pattern such as longer VOTs followed by shorter vowel durations in both languages. An asymmetry is found in CV interaction in that the effect of consonant on vowel duration is greater than the VOT differences induced by the vowel. Prosodic effects are found such that the acoustic difference is enhanced between the contrastive segments under focal accent, supporting the paradigmatic strengthening effect. Positional variation, however, does not show any systematic effects on the variations of the measured acoustic quantities. Overall vowel duration and syllable duration are longer in English tokens but involve less variability across the prosodic variations. The constancy of syllable duration, therefore, is not found to be more strongly sustained in Korean CDS. The stylistic variation is discussed in relation to the listener under linguistic development in CDS.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.18 no.1
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• pp.11-15
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• 2007

Background and Objectives: $VoCoM^{(R)}$ is a set composed of prefabricated hydroxylapatite implants and shims of various sizes that are designed for the type I thyroplasty, Authors aimed to evaluate the efficacy of $VoCoM^{(R)}$ System in type I thyroplasty. Materials and Method: Twenty three patients with unilateral vocal cord palsy were included in the study, who received type I thyroplasty with $VoCoM^{(R)}$ between May 2000 and May 2007 in St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea, Acoustic, aerodynamic and stroboscopic analyses were performed pre-and post-operatively, Subjective voice improvement was analysed by Voice handicap index, Results : Preoperative jitter was $4.68{\pm}2.46%$ and improved to $3.19{\pm}1.94%$(P<0,05), Preoperative NHR was $0.26{\pm}0.1$ and improved to $0.18{\pm}0,07$(P<0.05), Preoperative MPT was $6.16{\pm}4.9$secs improved to $9.55{\pm}4.67$secs(p<0.05), The postoperative stroboscopy revealed an effective medialization of vocal fold of all patients, Conclusion: Type I thyroplasty using $VoCoM^{(R)}$ is a efficient, safe and convenient way of vocal fold medialization at the expense of its high cost and difficulty in removal.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.14 no.1
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• pp.16-25
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• 2003

Background and Objectives : Electroglottography(EGG) is a non-invasive method of monitoring the vocal cord vibration by measuring the variation of physiological impedance across the vocal folds through the neck skin. It reveals especially the vocal fold contact area and is widely used for basic laryngeal researches, voice analysis and synthesis. The purpose of this study is to investigate the effectiveness of EGG parameters in differential diagnosis of laryngeal cancer. Materials and Methods : The author investigated 10 laryngeal cancer and 25 benign laryngeal disease patients who visited at the Department of Otolaryngology, Pusan National University Hospital. The EGG equipment was devised in the author's Department. Among various parameters of EGG, closed quotient(CQ), speed quotient(SQ), speed index(SI), Jitter, Shimmer, Fo were determined by an analysis program made with MATLAB 6.5$^{\circledR}$(Mathwork, Inc.). In order to differentiate various laryngeal diseases from pathologic voice signals, the author has used the electroglottographic parameters using the neural network of multilayer perceptron structure. Results : SQ, SI, Jitter and Shimmer values except those of CQ and Fo showed remarkable differences between benign and malignant laryngeal disease groups. From the artificial neural network, the percentage of differentiating the laryngeal cancer was over 80% in SQ, SI, Jitter, Shimmer except for CQ and Fo. These results indicated that it is possible to discriminate the benign and malignant laryngeal diseases by EGG parameters using the artificial neural network. Conclusion : If parameters of EGG which can reveal for the pathology of laryngeal diseases are additionally developed and the current classification algorithm is improved, the discrimination of laryngeal cancer will become much more accurate.

• Phonetics and Speech Sciences
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• v.12 no.4
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• pp.91-98
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• 2020

This study investigated the acoustic characteristics of sustained vowel /a/ and sentence utterance produced by patients with muscle tension dysphonia (MTD) using cepstrum-based acoustic variables. 36 women diagnosed with MTD and the same number of women with normal voice participated in the study and the data were recorded and measured by ADSVTM. The results demonstrated that cepstral peak prominence (CPP) and CPP_F0 among all of the variables were statistically significantly lower than those of control group. When it comes to the GRBAS scale, overall severity (G) was most prominent, and roughness (R), breathiness (B), and strain (S) indices followed in order in the voice quality of MTD patients. As these characteristics increased, a statistically significant negative correlation was observed in CPP. We tried to classify MTD and control group using CPP and CPP_F0 variables. As a result of statistic modeling with a Random Forest machine learning algorithm, much higher classification accuracy (100% in training data and 83.3% in test data) was found in the sentence reading task, with CPP being proved to be playing a more crucial role in both vowel and sentence reading tasks.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.30 no.2
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• pp.101-106
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• 2019

Background and Objectives Reinke's edema is a benign vocal fold disease caused by an edematous laryngeal superficial layer of lamina propria. The first line treatment is cessation of smoking and laryngeal microsurgery. The aim of the study is to evaluate the feasibility and efficacy of percutaneous steroid injection via cricothyroid membrane in patients with Reinke's edema. Materials and Method From Jan 2010 to July 2018, 33 Patients with Reinke's edema managed by vocal fold steroid injection via the cricothyroid membrane were included in this study. We compared medical records of laryngoscopy, stroboscopy and Multi-Dimensional Voice Program analysis at pre-treatment and post-treatment. Subjective voice improvement was evaluated using Voice Handicap Index-30 (VHI-30). Results 75.7% of the patients showed partial response and 6.06% showed complete response. 93.94% were present smokers and only 4 patients ceased smoking after the treatment. In acoustic analysis, the pre-treatment mean value of jitter, shimmer, and noise to harmonic ratio was 2.30±3.21, 9.34±10.37, 1.11±2.90 each. The post-treatment value was 2.20±1.89, 6.96±5.30, 0.20±0.09 respectively and none of the parameters were statistically significant. For subjective symptom improvement, 25 (75.8%) patients showed a better score on post-treatment VHI-30 compared to pre-treatment. Conclusion According to our study, steroid injection is a relatively safe and effective procedure for patients with Reinke's edema. A vocal fold steroid injection via the cricothyroid membrane can be an alternative treatment option for those who are not able to undergo conventional laryngeal microscopic surgery, however cessation of smoking is necessary for effective treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1161-1169
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• 2012

This study was investigate the usefulness of the DSI according to gender. The present study evaluated DSI in Korean population and Thirty voluntary participants (15 males, 15 females) who had G0 on the Grade, Roughness, Breathiness, Asthenics, Strain(GRBAS) and lived in Kyunggi-Do or Seoul, from March 2011 to June 2011. Maximum phonation time, the Highest fundamental frequency, the Lowest intensity, and Jitter(%) were measured using CSL 4500(Kay Pentax. USA). The experimenter explained the subjects the experimental condition and procedures and demonstrated the procedures, prior to the experiment. The result of in this study showed that the difference between males and females were not significants, although the Fhi was higher for females than for males. Therefore, We conclude that the DSI is a useful instrument to objectively measure the severity of dysphonia.

• International Commerce and Information Review
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• v.16 no.5
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• pp.225-248
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• 2014

Korea and China signed an FTA at November 10, 2014. The entry of China - the factory of the World - can be more active and easier. But Recently, China's economic growth is slowdown, and it began to emerge as a voice of concern. Therefore I analyze Chnia's economic slowdown is the impact on Korea's economy in this study. This study presented current trends and future prospects on China's economic situation. The changes of China's economic growth are the reduction of economic growth rate, falling proportion of processing trade, and the competition relationship of two countries. So they will be analyzed on this study. And this study presents ways that Korea economy reacts for China's economic growth slowdown. Trade statistics system of Korea International trade Association(KITA) is leveraged for this analysis. For competition relationship analysis, I analyze to use Contribution to the Trade Balance, Trade Specialization Index, Revealed Comparative Advantage of Country.