• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.19 no.1
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• pp.11-15
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• 2008

Endoscopic laser cordectomy is known as an oncologically sound procedure for T1 and selected T2 glottic carcinoma ; it has comparable local control rate and better long-term laryngeal preservation rate when compared with those of radiotherapy. Even if results of the reported voice outcome studies after surgery or radiotherapy are diverse and controversial, resection deeper than the body layer of the vocal fold (type III, IV, V cordectomy) usually leads to aerodynamic insufficiency during phonation and results in poor voice quality. A keyhole defect or development of synechiae at the anterior commissure after type VI cordecomy may also result in unsatisfactory vocal outcome. However, many advances in phonosurgical techniques are reported to be successfully applied in the reconstruction of glottal defect that is subsequent to endoscopic laser cordectomy. In case of glottal insufficiency, voice restoration can be achieved by means of augmentation of the paraglottic space or medialization of the excavated vocal fold. Injection laryngoplasty with synthetic materials or autologous fat is gaining its popularity for restoring minor glottal volume defect because of its convenience. Laryngeal framework surgery, especially type I thyroplasty with premade implant systems or Gore-Tex, is most frequently used to correct larger glottic volume defect. In case of anterior commissural keyhole defect, additional procedure including laryngofissure may be required. For anterior commissural synechiae, laryngeal keel may be inserted for several weeks or mitomycin-C may be repeatedly applied after the division of adhesive scar to prevent restenosis. In this paper, current concepts and the authors' experiences of phonosurgical reconstruction of vocal function after endoscopic cordectomy will be introduced.

• Wind and Structures
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• v.31 no.3
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• pp.229-240
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• 2020

In the present work, the main features of primary vortices and the vorticity concentrations downstream of vortex bursting in crossflow plane of a delta wing with a sweep angle of Λ=70° were investigated under the variation of the sideslip angles, β. For the pre-review of flow structures, dye visualization was conducted. In connection with a qualitative observation, a quantitative flow analysis was performed by employing Particle Image Velocimetry (PIV). The sideslip angles, β were varied with four different angles, such as 0°, 4°, 12°, and 20° while angles of attack, α were altered between 25° and 35°. This study mainly focused on the instantaneous flow features sequentially located at different crossflow planes such as x/C=0.6, 0.8 and 1.0. As a summary, time-averaged and instantaneous non-uniformity of turbulent flow structures are altered considerably resulting in non-homogeneous delta wing surface loading as a function of the sideslip angle. The vortex bursting location on the windward side of the delta wing advances towards the leading-edge point of the delta wing. The trajectory of the primary vortex on the leeward side slides towards sideways along the span of the delta wing. Besides, the uniformity of the lift coefficient, C_L over the delta wing plane was severely affected due to unbalanced distribution of buffet loading over the same plane caused by the variation of the sideslip angle, β. Consequently, dissimilarities of the leading-edge vortices result in deterioration of the mean value of the lift coefficient, C_L.

• International Journal of High-Rise Buildings
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• v.7 no.1
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• pp.17-32
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• 2018

This paper explores the function of a structural skin with an embossed surface applicable to use for tall building structures. The major diagrid system with a secondary embossed surface structure provides an enhanced perimeter structural system by increasing tube section areas and reduces aerodynamic loads by disorienting major organized structure of winds. A parametric study used to investigate an optimized configuration of the embossed structure revealed that the embossed structure has a structural advantage in stiffening the structure, reducing lateral drift to 90% compared to a non-embossed diagrid baseline model, and results of wind load analysis using computational fluid dynamics, demonstrated the proposed embossed system can reduce. The resulting undulating embossed skin geometry presents both opportunities for incorporating versatile interior environments as well as unique challenges for daylighting and thermal control of the envelope. Solar and thermal control requires multiple daylighting solutions to address each local façade surface condition in order to reduce energy loads and meet occupant comfort standards. These findings illustrate that although more complex in geometry, architects and engineers can produce tall buildings that have less impact on our environment by utilizing structural forms that reduce structural steel needed for stiffening, thus reducing embodied $CO^2$, while positively affecting indoor quality and energy performance, all possible while creating a unique urban iconography derived from the performance of building skin.

• Environmental Analysis Health and Toxicology
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• v.21 no.1 s.52
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• pp.57-69
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• 2006

Lately human exposure to fine particles smaller than $2.5{\mu}m$ in aerodynamic diameter ($PM_{2.5}$) has become a great concern in Korea due to their possible cause of elevated mortality, lung function decrements, and more frequent hospital admissions for asthma. This study was conducted to investigate seasonal variations of human exposure to residential $PM_{2.5}$ and particle-associated polycyclic aromatic hydrocarbons (PAHs). Ten homes in Chuncheon, Korea were visited for continuous 72 hour sampling of $PM_{2.5}$ in the living rooms using a MiniVol Portable Sampler from December 22, 2002 to November 3, 2003. During the same period, outdoor $PM_{2.5}$ samples were collected on the top of the Natural Sciences Building of Kangwon National University which is located in the middle of the ten households. Samples were analyzed for $PM_{2.5}$ mass concentrations and six selected PAHs. In two smoking homes, the highest $PM_{2.5}$ concentrations were measured ranging from 51.1 to 69.7 {\mu}g/m^3$ on average in all seasons, indicating smoking is a very important contributor to the elevation of indoor particle concentrations. Seasonal comparison showed that indoor particle concentrations were higher than outdoor ones except winter. Total PAH concentrations in smoking homes were highest in winter among the seasons primarily due to low ventilation rate, followed by the outdoor site and nonsmoking homes. BaP toxic equivalents (TEQs) were calculated for five PAHs. The TEQ for smoking homes in winter was highest followed by the outdoor site in winter. It is concluded that smoking and ventilation rate are two important contributors to the elevation of indoor $PM_{2.5}$ and PAH concentrations.

• Speech Sciences
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• v.1
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• pp.153-200
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• 1997

In languages such as Japanese, it is very common to observe that short peripheral vowel are completely voiceless when surrounded by voiceless consonants. This phenomenon has been known as Montreal French, Shanghai Chinese, Greek, and Korean. Traditionally this phenomenon has been described as a phonological rule that either categorically deletes the vowel or changes the [+voice] feature of the vowel to [-voice]. This analysis was supported by Sawashima (1971) and Hirose (1971)'s observation that there are two distinct EMG patterns for voiced and devoiced vowel in Japanese. Close examination of the phonetic evidence based on acoustic data, however, shows that these phonological characterizations are not tenable (Jun & Beckman 1993, 1994). In this paper, we examined the vowel devoicing phenomenon in Korean using data from ENG fiberscopic and acoustic recorders of 100 sentences produced by one Korean speaker. The results show that there is variability in the 'degree of devoicing' in both acoustic and EMG signals, and in the patterns of glottal closing and opening across different devoiced tokens. There seems to be no categorical difference between devoiced and voiced tokens, for either EMG activity events or glottal patterns. All of these observations support the notion that vowel devoicing in Korean can not be described as the result of the application of a phonological rule. Rather, devoicing seems to be a highly variable 'phonetic' process, a more or less subtle variation in the specification of such phonetic metrics as degree and timing of glottal opening, or of associated subglottal pressure or intra-oral airflow associated with concurrent tone and stricture specifications. Some of token-pair comparisons are amenable to an explanation in terms of gestural overlap and undershoot. However, the effect of gestural timing on vocal fold state seems to be a highly nonlinear function of the interaction among specifications for the relative timing of glottal adduction and abduction gestures, of the amplitudes of the overlapped gestures, of aerodynamic conditions created by concurrent oral tonal gestures, and so on. In summary, to understand devoicing, it will be necessary to examine its effect on phonetic representation of events in many parts of the vocal tracts, and at many stages of the speech chain between the motor intent and the acoustic signal that reaches the hearer's ear.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.78-83
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• 2010

In the present paper, a flap was optimized to maximize the lift. A 2-element fowler flap system was utilized for optimization with an initial shape of general aviation airfoil and a flap shape designed by Wentz. Response surface method and Hicks-Henne shape function were implemented for optimization. 2-D Navier-Stokes method was used to solve flow field around aGA(W)-1 airfoil with a fowler flap. Commercial programs including Visual-Doc, Gambit/Tgridand Fluent were used. Upper surface shape and the flap gap were optimized and lift for landing condition was improved considerably. The original and optimized flaps were tested in the KARI's 1-m low speed wind tunnel to examine changes in aerodynamic characteristics. For optimized flap tests, the similar trend to prediction could be seen but stall angle of attack was lower than what was expected. Also, less gap than optimized design delayed stall and produced better lift characteristics. This is believed to be the effect of turbulence model.

• Smart Media Journal
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• v.8 no.4
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• pp.38-45
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• 2019

When there is a spray flow such as from a pesticide nozzle, winds affect the droplet flow of a rotary-wing drone accompanied by a strong wake, with a severe oscillation. Especially, during forwarding flights or when winds come from the side, compare to a simple hovering flight as the droplet is in the effect of aerodynamic drag force, the effect of spraying region becomes even larger. For this reason, the spraying of pesticides using drones may cause a greater risk of scattering or a difference in droplet dispersion between locations, resulting in a decrease in efficiency. Therefore, through proper numerical modeling and its applied simulation, an indication tool is required applicable for the various flight and atmospheric conditions. In this research, we completed both experiment and numerical analysis for the strong downwash from the rotor and flight velocity of the drone by comparing the probability density function of droplet distribution to build a spraying system that can improve the efficiency when spraying droplets in the pesticide spray drone.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.18 no.1
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• pp.44-50
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• 2007

Background and Objectives: The 585-nm pulsed dye laser (PDL) has recently been adopted by otolaryngologists because of its epithelial-sparing properties. Many authors have reported the use of PDL for treatment of various vocal cord lesions. This purpose of this study is to examine the effectiveness of 585-nm PDL in the treatment of vocal polyp. Materials and Methods: Eight patients with vocal polyp were treated with 585-nm PDL from Sep. 2006 to Nov. 2006 in Yong-dong Sevrance hospital. 5 of them went through local anesthesia and 3 of them went through general anesthesia. In order to control laser fiber, flexible digital transnasal laryngoscope was applied under local anesthesia and general anesthesia using LMA, and micromanipulator was used under general anesthesia using endotracheal tube. The evaluations of vocal function was done at pre-and postoperation. Results: All patients improved in the perceptual evaluation of voice after PDL surgery. The aerodynamic study revealed that 5 of 8 patients showed improvement in maximal phonation time, and 6 of 8 showed improvement in mean airflow rate during phonation. The acoustic analysis revealed that all patients showed improvement in Jitter and Shimmer, and 7 of 8 showed improvement in noise to harmony ratio. Conclusion: This study demonstrates promising results in the efficacy of 585-nm PDL for the treatment of vocal polyps, and it illustrates a new option for vocal polyp treatment as well as the advantage of PDL surgery.

• Journal of the Korea Society of Computer and Information
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• v.11 no.4 s.42
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• pp.35-45
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• 2006

RIn this paper. we describe real-time parallel processing simulator developed for the use of performance analysis of rolling missiles. The real-time parallel processing simulator developed here consists of seeker emulator generating infrared image signal on aircraft, real-time computer, host computer, system unit, and actual equipments such as auto-pilot processor and seeker processor. Software is developed according to the design requirements of mathematic model, 6 degree-of-freedom module, aerodynamic module which are resided in real-time computer. and graphic user interface program resided in host computer. The real-time computer consists of six TI C-40 processors connected in parallel. The seeker emulator is designed by using analog circuits coupled with mechanical equipments. The system unit provides interface function to match impedance between the components and processes very small electrical signals. Also real launch unit of missiles is interfaced to simulator through system unit. In order to use the real-time parallel processing simulator developed here as a performance analysis equipment for rolling missiles, we perform verification test through experimental results in the field.

• Food Science and Preservation
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• v.23 no.5
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• pp.746-752
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• 2016

This research was carried out to identify aerodynamic property as a function of moisture content for designing equipment such as for post-harvest management. Terminal velocity of two wheat varieties {Backjjung (B) and Jogyeong (J)} with selected sound, damaged kernel and foreign materials (Wheat stick, Wheat husks) were measured with a designed vertical wind column at different moisture contents from about 9 to 30% wet basis. The results showed that terminal velocity of wheat and foreign materials except of Jogyeong's husks (p<0.05) had a significant difference at p<0.001. With increasing moisture content, the aerodynamic property values of the kernels and foreign materials of the two wheat varieties increased linearly. In detail, terminal velocity of sound and damaged kernel increased from 5.46 to 7.13 m/sec (B) and 7.48 to 8.60 m/sec (J), damaged kernel from 5.91 to 7.00 m/sec (B) and 6.48 to 7.75 m/sec (J). For foreign materials the terminal velocity of wheat stick increased from 2.92 to 4.07 m/sec (B) and 3.74 to 5.22 m/sec (J) whereas that of husks from 1.07 to 1.85 m/sec (B) and 2.02 to 2.33 m/sec (J) each. For air separation of wheat and foreign materials, the air flow should be less than 5.22 m/sec due to the range (1.07~5.22 m/sec) of foreign materials in wheat.