• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.385-390
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• 2006

This paper examines the sampling and jitter specifications and considerations for Global Navigation Satellite Systems (GNSS) software receivers. Software radio (SWR) technologies are being used in the implementation of communication receivers in general and GNSS receivers in particular. With the advent of new GPS signals, and a range of new Galileo and GLONASS signals soon becoming available, GNSS is an application where SWR and software-defined radio (SDR) are likely to have an impact. The sampling process is critical for SWR receivers, where it occurs as close to the antenna as possible. One way to achieve this is by BandPass Sampling (BPS), which is an undersampling technique that exploits aliasing to perform downconversion. BPS enables removal of the IF stage in the radio receiver. The sampling frequency is a very important factor since it influences both receiver performance and implementation efficiency. However, the design of BPS can result in degradation of Signal-to-Noise Ratio (SNR) due to the out-of-band noise being aliased. Important to the specification of both the ADC and its clocking Phase- Locked Loop (PLL) is jitter. Contributing to the system jitter are the aperture jitter of the sample-and-hold switch at the input of ADC and the sampling-clock jitter. Aperture jitter effects have usually been modeled as additive noise, based on a sinusoidal input signal, and limits the achievable Signal-to-Noise Ratio (SNR). Jitter in the sampled signal has several sources: phase noise in the Voltage-Controlled Oscillator (VCO) within the sampling PLL, jitter introduced by variations in the period of the frequency divider used in the sampling PLL and cross-talk from the lock line running parallel to signal lines. Jitter in the sampling process directly acts to degrade the noise floor and selectivity of receiver. Choosing an appropriate VCO for a SWR system is not as simple as finding one with right oscillator frequency. Similarly, it is important to specify the right jitter performance for the ADC. In this paper, the allowable sampling frequencies are calculated and analyzed for the multiple frequency BPS software radio GNSS receivers. The SNR degradation due to jitter in a BPSK system is calculated and required jitter standard deviation allowable for each GNSS band of interest is evaluated. Furthermore, in this paper we have investigated the sources of jitter and a basic jitter budget is calculated that could assist in the design of multiple frequency SWR GNSS receivers. We examine different ADCs and PLLs available in the market and compare known performance with the calculated budget. The results obtained are therefore directly applicable to SWR GNSS receiver design.

• 한국정보전자통신기술학회논문지
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• 제15권4호
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• pp.237-242
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• 2022

관제 및 측정 시스템 등에서 고품질 영상을 획득하는 것은 중요한 요소 중 하나이다. 영상 획득 기술 중에서 SFF (Shape from Focus)는 물체를 광축 방향으로 사전에 결정된 스텝 사이즈로 이동시킴으로써 초점 정도가 다른 2D 영상들을 획득함으로써 삼차원 형상을 복원하는 기술이다. SFF를 위해 일정한 스텝 사이즈로 물체를 이동시킬 때 각 스텝에서 광축 방향으로 기계 진동, 즉 지터 노이즈가 발생한다. 본 논문에서는 이 지터 노이즈의 영향을 줄이기 위해 새로운 상태 추정 필터를 설계 및 적용한다. 제안된 방법의 적용을 위해 지터 노이즈와 초점 커브는 가우시안 함수로써 모델링한다. 실험 결과들을 통해 제안된 방법의 효율성을 증명한다.

• 음성과학
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• 제8권4호
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• pp.87-98
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• 2001

Vocal nodule is one of the representative chronic diseases of vocal folds, and it can be cured by surgical removal or voice therapy. The aim of this study is to evaluate the effect of the accent method, one of the popular effective voice therapy, in the patients with vocal nodule. Authors executed the accent method in 17 patients with vocal nodule who visited the Voice & Speech Therapy Clinic, Pusan National University Hospital analysed the voice before and after treatment using the local findings, acoustic analysis and aerodynamic analysis MPT. The voice was analysed with MDVP of CSL and MPT was checked using stop watch. The parameters included Fo, Jitter, Shimmer and noise to harmonic ratio(NHR) as acoustic analysis. The results were obtained as follows. In the evaluation by the local findings, it was improved to 77% in the patients of vocal nodule. Jitter and Shimmer were shown to be improved significantly. In particular, it was shown to be improved significantly in patients with vocal nodule. As the result of this study, the improvement of aerodynamic aspect was more statistically significant than that of acoustic parameters. When I generalized the above mentioned results, we suggest that it is a useful voice therapy which can be helpful to the improvement of voice, applying the accent method to the vocal nodule patients, and there are currently many methods to be used in the voice therapy, but it is thought which the accent method is the good treatment as the alternatives of keeping the continuous medical treatment.

• 대한후두음성언어의학회지
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• 제27권1호
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• pp.40-44
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• 2016

Background and Objectives : Surgery is considered the primary treatment for intracordal cyst. However, patients who had undergone surgery are still subject to recurrence and continued voice changes. Intracordal cysts naturally disappear in some patient population. Cyst does not always recur in patients who had received partial surgical removal, too. Contradicting results raises a question whether complete surgical removal of intracordal cyst is necessary and demonstrate need for better treatment. Herein, the author proposes novel surgical method technique intralaryngeal needle technique (INT), a technique using surgical needle for not only injection but also for aspiration and excision of cyst. This study aims to examine the potential of intralaryngeal needle technique in treating intracordal cysts. Materials and Methods : Surgical procedures were done on in-patients diagnosed with intracordal cyst. 23 patients received follow-up screening after the surgery for one year. Patients' subjective satisfaction levels, acoustic measures, aerodynamic measures, laryngeal stroboscopic results were compared before and after the treatment. Results : Overall patients were satisfied with novel surgical excision method. In terms of aerodynamic measures, maximum phonation time, mean air flow rate improved after the surgery. In terms of acoustic measures, Jitter, Shimmer, NHR, and voice pitch changes after the treatment showed statistically significant differences. Laryngeal stroboscopy results showed significant decreases in cyst sizes. Post-surgery patients had improved mucosal waves and amplitudes values. Conclusion : The results show the validity of intralaryngeal needle technique in reducing intracordal cyst size by excision, aspiration, and injection. The author believes this novel technique can be used as an alternative surgical method for intracordal cysts.

• 한국멀티미디어학회논문지
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• 제21권10호
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• pp.1162-1170
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• 2018

This paper presents an augmented reality system for multiple users. The proposed system performs ar image-based pose estimation of users and pose of each user is shared with other uses via a network server. For camera-based pose estimation, we install multiple markers in a pre-determined space and select the marker with the best appearance. The marker is detected by corner point detection and for robust pose estimation. the marker's corner points are tracked by optical flow tracking algorithm. Experimental results show that the proposed system successfully provides an augmented reality application to multiple users even when users are rapidly moving and some of markers are occluded by users.

• 한국통신학회논문지
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• 제22권1호
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• pp.139-150
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• 1997

For high-speed networks, a new ring protocal is proposed in this paper. A ring network combined with destination removal can achieve much higher network throughput than the channel transmission rate. However, such a network exhibits fairness problems. Over a past few years, global fairness algorithms such as ATMR and Metaring have been proposed to solve such problems. But the ring access time delay and fairness in such networks are sensitive to the network parameters such as network size and traffic distribution. In addition to guaranteeing fair ring access to all nodes, there are several other important performance aspects in such networks. The one is that fairness is enforced while node throughputs are kept as high as possible. And another performance measure is access delay and more specifically Head-Of-Line(HOL) delay, i.e., the amount of time the first cell in the transmission buffer of a node has to wait before it accesses the ring. HOL delay is a mijor component in the transmission jitter of the synchronous traffic transmission. A key idea of the proposed ring protocol is to find the nodes that have much more chances to access the ring than any other nodes in the independently distributed node architecture. Since destined by many cells need to share a part of the bandwidths with the next node for the fairness in as much as performance degradation does not become critical. To investigate the performance behavior of the proposed ring protocol for various network condition,s several performance parameters wuch as ring access time delay, and throughput are compared with those of the ATMR and Metaring protocols using simulation package, SIMAN.

• 대한후두음성언어의학회지
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• 제18권1호
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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.