• Wind and Structures
• /
• v.32 no.3
• /
• pp.179-191
• /
• 2021

A series of wind tunnel tests, including 1:50 sectional model tests, 1:50 free-standing bridge tower tests and 1:70 full-bridge aeroelastic model tests were carried out to systematically investigate the aerodynamic performance of the Hong Kong-Zhuhai-Macao Bridge (HZMB). The test result indicates that there are three wind-resistant safety issues the HZMB encounters, including unacceptable low flutter critical wind speed, vertical vortex-induced vibration (VIV) of the main girder and galloping of the bridge tower in across-wind direction. Wind-induced vibration of HZMB can be effectively suppressed by the application of aerodynamic and mechanical measures. Acceptable flutter critical wind speed is achieved by optimizing the main girder form (before: large cantilever steel box girder, after: streamlined steel box girder) and cable type (before: central cable, after: double cable); The installations of wind fairing, guide plates and increasing structural damping are proved to be useful in suppressing the VIV of the HZMB; The galloping can be effectively suppressed by optimizing the interior angle on the windward side of the bridge tower. The present works provide scientific basis and guidance for wind resistance design of the HZMB.

• Journal of Korean Society of Steel Construction
• /
• v.19 no.2
• /
• pp.147-160
• /
• 2007

In this paper, we described the aeroelastic full-bridge model tests that were conducted to investigate the effect of alternative temporary stabilizing measures for thecable-stayed bridge during construction to ensure aerodynamic stability in the event of a typhoon or similar disasters. The effect of alternative temporary stabilizing measures was investigated through various configurations on two cable-stayed bridges with a main span of 475 m and 230 m, respectively. To investigate the bridge's aerodynamic behaviour and dynamic wind force during construction, the deflections at the end of the cantilever, the accelerations atthe top of the pylon and the moments at the lower part of the pylon were measured. As the result, the system with two sets of vertical cables per cantilever seemed to be the overall most effective solution, but the system with single vertical cable may also work. The combined system using the caisson support and vertical cables and the system with two sets of inclined cables per cantilever on the same anchor block may also be a solution. The inclined cables from the caisson to the girder were effective for some early stages of erecting the deck.

• Wind and Structures
• /
• v.35 no.6
• /
• pp.405-418
• /
• 2022

The aerodynamic behaviour of a CRH high-speed train under three infrastructure scenarios (flat ground, embankment, and viaduct) in the presence of a crosswind was simulated using a 1/8th scaled train model with three cars and the IDDES framework. The time-averaged and instantaneous flow field around the model were examined. The employed numerical algorithm was verified through a wind tunnel test, and the grid and timestep resolution analyses were conducted to ensure the reliability of the data. It was noted that the flow around the rail line was different under different infrastructure scenarios, especially in the case of the embankment, which degraded the aerodynamic performance of the train under the crosswind. The flow around the train on the flat ground and viaduct was different, although the aerodynamic performance of the train was similar in both cases. Moreover, the viaduct accidents were noted to have the most critical consequences, thereby requiring the most attention. The aerodynamic performance of the train on the windward track of the embankment under the crosswind was worse than that of the train on the leeward track. But for the other two infrastructure scenarios, the aerodynamic performance of the train on the windward track is relatively dangerous, which is mainly caused by the head car. These observations suggest that the aerodynamic behaviour of the train on an embankment under a crosswind must be carefully considered and that certain wind protection measures must be adopted around rail lines in windy areas.

• Particle and aerosol research
• /
• v.19 no.4
• /
• pp.155-164
• /
• 2023

APS (Aerodynamic Particle Sizer) and OPC (Optical Particle Counter) have been widely used to real-time measurement of indoor and outdoor aerosols. The APS measures the size distribution based on an aerodynamic diameter, while the OPC uses optical diameter to measure the size distribution of aerosols. Since obtaining a size distribution based on aerodynamic diameter is important to understand aerosol characteristics, lots of researcher had been developed experimental equations which can convert optical diameter into aerodynamic diameter. However, previous studies have conducted repeated experiments on particles having a single diameter. In this study, an experimental method of converting optical diameter into aerodynamic diameter through a single experiment was presented. The collection efficiencies of an axial cyclone were measured using APS and OPC at the same time, and the correlation equation between aerodynamic diameter and optical diameter was driven through a theoretical model. Using the proposed method, the size distribution of NaCl particles measured by OPC showed a high correlation with the size distribution obtained by APS (0.93 of R-squared value). In the tests conducted on ISO A1, A2, and A4 test particles, the converted OPC size distribution tended to be similar to the APS size distribution, and for each of test particles (ISO A1, A2, and A4), the R-squared values for the APS particle size distribution were 0.75, 0.86, and 0.89, respectively.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
• /
• v.17 no.1
• /
• pp.43-48
• /
• 2006

Background and Objectives: Countertenors who can produce higher vocal pitch like female classical singer's voice and use both modal and falsetto register. This study was conducted to study phonatory characteristics between modal and falsetto register of the countertenor. Materials and Methods: A male countertenor who had 8 years of experience was examined using a videostroboscopy and his voice was analyzed using aerodynamic measures; fundamental frequency(F0), Mean air flow rate(MFR), intensity(SLP), subglottal air pressure(Psub) with phonatory function analyzer(Nagashima) and acoustic measures; jitter, shimmer, HNR, closed quotient(CQ) using a Electro-glottography(EGG) of Lx. Speech Studio(Laryngoscope, Ltd, UK) and voice range profile of CSL(Kay elemetrics). Results: In the stroboscopy finding, the longitudinal length of vocal folds was increased at the falsetto register and the upper margin of vocal folds vibrated with incomplete closure of true vocal folds. In aerodynamic analysis, intensity was same at the modal and falsetto register. However, MFR, Psub, MPT were higher at the falsetto register. In the electroglottographic analysis, closed quotient(CQ) at the modal register was high and also much higher at the high-pitch falsetto than at the loud falsetto. In the VRP, intensity was similar though F0 was different between modal and falsetto register. Conclusion: It implied that countertenor could produce powerful voice quality by increasing of respiratory pressure and respiratory volume though glottal closure was incomplete. In addition, no change of EGG waveform, similar voice range with alto was observed.

• Proceedings of the KSPS conference
• /
• 2002.11a
• /
• pp.129-132
• /
• 2002

Aerodynamic analysis study was performed on 14 normal subjects(2 male, 12 female) by nonsense syllables composed of Korean bilabial stop(/p, p', $p^{h}$) and their preceding and/or following vowel /i, a, u/. That is [pi, p'i, phi, pa, p'a, pha, pu, p'u, $p^{h}u$]. All measures were analysed using Aerophone II voice function analyzer and included peak air pressure, mean air pressure, maximum flow rate, volume, mean SPL. As results, first, MSPL and MAP of /p, p', $p^{h}$/ themselves were significantly different. In addition, different vowel enviroment also produced significantliy different aerodynamic chracteristics those consonants.

• Speech Sciences
• /
• v.9 no.4
• /
• pp.59-75
• /
• 2002

Aerodynamic analysis study was performed on 14 normal subjects (2 males, 12 females) with nonsense syllables composed of Korean bilabial stops (/p, p', $p^{h}$) and their preceding and/or following vowels, /i, a, u/. That is, [pi, p'i, $p^{h}i$, pa, p'a, $p^{h}a$, pu, p'u, $p^{h}u$, ipi, apa, upu, $ip^{h}i$, $ap^{h}a$, $up^{h}u$, ip'i, ap'a, up'u]. All measures were taken and analysed using Aerophone II voice function analyzer and included peak air pressure, mean air pressure, maximum flow rate, volume, mean SPL and phonatory SPL. A t-test and one-way ANOVA were employed for analysis. A post-hoc analysis was performed with Scheffe and Bonferroni. The results were as follows: First, MSPL. and MAP of /p, p', $p^{h}$/ were significantly different in different positions (initial and medial position). In addition, different vowel environment also produced significantly different aerodynamic characteristics those consonants. Especially the lax consonant /p/ was significantly different /i, a, u/ vowel environments. The tense consonant /p'/ was significantly different only /i/ vowel environment.

• Phonetics and Speech Sciences
• /
• v.3 no.3
• /
• pp.167-172
• /
• 2011

The purpose of this study was to examine the relationship between subjective and objective evaluation in speakers with voice disorders. Subjective evaluation indicates the self-reports of voice problems by dysphonic speakers. The relating protocol is the Voice Handicap Index (VHI) and the self-awareness index of voice problems (SAIVP-14). A total of 48 individuals with voice disorders replied to the questionnaire and participated in a voice assessment. Objective evaluations included the perceptual judgement of G grade in GRBAS, acoustic measurements (jitter, shimmer, NHR) by MDVP (CSL 4400), and aerodynamic measurements (MPT, MFR, psub) by PAS (Phonatory Aerodynamic System, KayPentax, USA). Pearson and Spearman correlations were used for the analysis. In the correlation with perceptual judgement (G grade) and VHI-Total, VHI-Physical, and SAIVP-14, there was a significant correlation, but the overall correlation was poor. NHR, jitter, and shimmer were significantly correlated with overall VHI and SAIVP-14. Specifically, the correlation with shimmer was stronger compared to the other measurements. In aerodynamic measures, MFR and MPT showed a significant correlation with VHI-Total, VHI-Emotional, and SAIVP-14, but their correlation was poor. The results of this study suggested that subjective evaluation of self voice problems is meaningfully correlated with objective evaluations, but more data in the multidimensional voice assessment should be collected and analyzed for the reliability and validity of the voice handicap questionnaire.

• The Journal of the Korea Contents Association
• /
• v.19 no.12
• /
• pp.270-278
• /
• 2019

This study was performed to compare the aerodynamic characteristics of young and elderly adult male patients with voice disorders during continuous speech. Aerodynamic measurements were obtained after 12 young male patients and 9 elderly male patients read a paragraph. The elderly group showed longer duration, lower airflow rate and air volume than the younger group, but the differences were not significant except phonation time. So, when interpreting the meaning of aerodynamic measures of elderly voice disorder patients in the aspects of airflow and air volume, it should take into account various conditions(e. g. reading materials, pulmonary functions) as well as age.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
• /
• v.27 no.1
• /
• pp.40-44
• /
• 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.