• Steel and Composite Structures
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• v.43 no.4
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• pp.501-509
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• 2022

Cracks are common defects in concrete structures. Thus far, crack inspection has been manually performed using the contact inspection method. This manpower-dependent method inevitably increases the cost and work hours. Various non-contact studies have been conducted to overcome such difficulties. However, previous studies have focused on developing a methodology for non-contact inspection or local quantitative detection of crack width or length on concrete surfaces. However, crack depth can affect the safety of concrete structures. In particular, although macrocrack depth is structurally fatal, it is difficult to find it with the existing method. Therefore, an experimental investigation based on non-contact infrared thermography and multivariate machine learning was performed in this study to estimate the hidden macrocrack depth. To consider practical applications for inspection, an experiment was conducted that considered the simulated piloting of an unmanned aerial vehicle equipped with infrared thermography equipment. The crack depths (10-60 mm) were comparatively evaluated using linear regression, gradient boosting, and random forest (AI regression methods).

• Journal of Oral Medicine and Pain
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• v.23 no.4
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• pp.457-473
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• 1998

This study was performed to investigate the morophological and positional correlation between the upper cervical vertebra, the oral structures and the pharyngeal tissues, and the correlation of these anatomical structures with dental features, such as teeth wear area nad tooth contact status, etc. Seventy patients with temporamandibular disorders and sixty three dental students without any signs and symptoms in head and neck region were selected for this study. All they had natural dentition without any fixed and removable protheses. Teeth wear area and arch width wre measured from the upper dental cast, tooth contact status were observed by T-Scan system$^\textregistered$ and four cephaloradiograpohs were taken from four head postures, namely, natural(NHP), forward(FHP), upward(UHP), and downward head postiure(DHP). 22 cephalometric items were measured on the films and the data were processed with SAS statistical program. The result of this study were as follows : 1. In normal group, angle of cervical vertebra tangent and of between hard and soft palate were broader in female subjects than those in male subjacets, but distance from subocciput to axis, size of soft palate, and pharyngeal space width were larger in male subjects. 2. In normal group with natural head posture, the items correlated each others from the three anatomical regions were distance between first nad second vertebra in posterior part, distance from the lingual surface of lower anterior teeth to anterior surface of soft palate, and distance from the hyoid bone to third vertebra. 3. Three set of items showed significant correlation each other in the four head postures in normal group. First set was the angle between hard and soft palate and the idstance from subocciput to posterior arch of first vertebra, second set was the distance between first and second vertebra in posterior part and the teeth wear area, third set was number and force of tooth contact and length of soft palate and distance from anterior tip of hyoid bone to mandibular plane.

• Korean Journal of Agricultural Science
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• v.47 no.2
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• pp.327-335
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• 2020

The purpose of this study was to analyze the load distribution and contact safety factor for the power take off (PTO) gear of a 71 kW class agricultural tractor. In this study, a simulation model of the PTO gear-train was developed using Romax DESGINER. The face load factor and contact safety factor were calculated using ISO 6336:2006. The simulation time was set at 2,736 hours considering the lifetime of the tractor, and the simulation was performed for each PTO gear stage at the engine rated power conditions. As a result of the simulation, the face load factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.644, 1.632, and 1.341, respectively. The contact safety factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.185, 1.216, and 1.458, respectively. As the PTO gear stage was increased, the face load factor decreased, and the contact safety factor increased. The load distributions for all the PTO gears were concentrated to the right of the tooth width. This causes stress concentrations and shortens the lifespan of the gears. Therefore, it is necessary to improve the face load factor and the contact safety factor with macro-geometry and micro-geometry.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.9-12
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• 2002

A parametric study has been conducted to investigate the effect of the geometry on the strength of an unidirectional and fabric hybrid laminated composite joint. Tests are conducted for the specimens with nine different edge-to-hole diameter or width-to-hole diameter ratios. For the finite element analysis, the characteristic length method is used, and the tests for determining the characteristic length are performed additionally. Nonlinear contact problem between the pin and laminate is modeled by the gap element in MSC/NASTRAN. Tsai-Wu failure criteria is applied to the stress on the characteristic curve. The finite element and experimental results shows good agreement in strength of composite joint. Results of the parametric study shows the effect of the geometry is remarkable in the specimens with width-to-hole diameter ratio less than 2.8 and edge-to-hole diameter ratio less than 1.4.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.763-768
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• 2002

This paper presents a mathematical model predicting the temperature distribution in rotating GMA welding. The bead width increases with rotation frequency at the same rotation diameter because the molten droplets are deflected by centrifugal force. The numerical solution is obtained by solving the transient three-dimensional heat conduction equation considering the heat input from the welding arc, cathode heating and molten droplets. Generally in GMA welding the heat input may be assumed as a normally distributed source, but the droplet deflection causes some changes in the heat input distribution. To estimate the heat flux distribution due to the molten droplet, the contact point where the droplet is transferred on the weld pool surface is calculated from the flight trajectory of the droplets under the arc plasma velocity field obtained from the arc plasma analysis. The numerical analysis shows a tendency of broadened bead width and shallow penetration depth with the increase of rotating frequency. The simulation results are in good agreement with those obtained by the experiments under various welding conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.10
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• pp.875-880
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• 2008

In this paper, we deal with the TLP evaluation results for GGNMOS in ESD protection device of conventional CMOS process. An evaluation parameter for GGNMOS is that repeatability evaluation for reference device($W/L=50\;{\mu}m1.0\;{\mu}m$) and following factors for design as gate width, number of finger, present or not for N+ gurad -ring, space of N-field region to contact and present or not for NLDD layer. The result of repeatability was showed uniformity of lower than 1 %. The result for design factor evaluation was ; 1) gate width leading to increase It2, 2) An increase o( finger number was raised current capability(It2), and 3) present of N+ gurad-ring was more effective than not them for current sink. Finally we suggest the optimized design conditions for GGNMOS in evaluated factor as ESD protection device of conventional CMOS process.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.10
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• pp.433-437
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• 2005

This paper studied Rotary type ultrasonic motor which has cross type stator. The stator consists of hollowed cross type metal which has four piezoelectric ceramics on the ends of cross bars. When two harmonic voltages which have 90$^{\circ}$ phase difference given to ceramics, the elliptical motion was generated in the inside tips. Inside tips are contact with rotor and these elliptical motions are rotate the rotor The finite element analysis was used to optimize the dimension and displacement of the stator. And the analyzed results were compared with the experimental results of the motor. As results, the speed and the torque of motor was increased by increasing width of the cross bar. And the speed and torque o( motor was not influenced to length of cross bar. The speed and torque was linearly increased by increasing voltage. The maximum torque was generated when the motor fabricated length of cross bar and width of ceramics in the ratio of 1:2.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.8 no.1
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• pp.18-26
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• 1997

There are two types of phonetic study, acoustic and physiologic, for differentiating the three manner categories of Korean stop consonants. On the physiologic studies, there are endoscopic, electromyographic(EMG), electroglottographic(EGG) and aerodynamic studies. In this study, I tried to investigate general features of Korean stops using EGG study for the open quotient of vocal fold and baseline shift during speech, and aerodynamic characteristics for e subglottal air pressure, air flow and glottal resistance at consonants. On the aerodynamic study, the glottalized and aspirated stops may be characterized by e increasing subglottal pressure comparing with lenis stop at consonants. The airflow is largest in the aspirated stops followed by lenis stops and glottalized. The glottal airway resistance (GAR) showed highest in the glottalized followed by the lenis, but lowest in e aspirated during e production of consonants, and showed highest in e aspirated, but low in the glottalized and lenis during the production of vowel. The glottal resistance at consonant showed significant difference among consonants and significant interaction between subject and types of consonant. The glottal resistance at vowel showed significant difference among consonants, and e interaction occured between subject and types of consonant. The electroglottography(EGG) has been used for investigating e functioning of e vocal folds during its vibration. The EGG should be related to the patterns of the vocal fold vibration during phonation in characterizing the temporal patterns of each vibratory cycle. The purpose of this study is to investigate the dynamic change of EGG waveforms during continuous speech. The dynamic changes of EGG waveforms fir the three-way distinction of Korean stops were characterized that the aspirated stop appears to be characterized by largest open quotient and smallest glottal contact area of the vocal folds in e initial portion of vocal fold vibration ; the lenis stop by moderate open quotient and glottal contact area ; but the glottalized stop by smallest open quotient and largest glottal contact area. There may be close relationship between the OQ(open quotient) in the initial voice onset and the glottal width at the time of consonant production, the larger glottal width just before vocal fold vibration results in the smaller OQ of the vocal fold vibration in the initial voice onset. The EGG changes of baseline shift during continuous speech production were characterized by the different patterns for the three types of Korean consonants. The small and less stiffness change of baseline shift was found for the lenis and the glottalized, and the largest and stiffest change was found for the aspirated. On the baseline shift for the initial voice onset, they showed so similar patterns with for the consonant production, larger changed in the aspirated. for the lenis and the glottalized during the initial voice onset, three subjects showed individual difference each other. I suggest at s characteristics were strongly related with articulatory activity of vocal tract for the production of consonant, especially for the aspirated stop. The suspecting factors to affect EGG waveforms are glottal width, vertical laryngeal movement and the intrapharyngeal pressure to neighboring tissue during connected spech. So the EGG may be an useful method to describe laryngeal activity to classify pulsing conditions of the larynx during speech production, and EGG research can be controls for monitoring the vocal tract articulation, although above factors to affect EGG would have played such a potentially role on vocal fold vibratory behavior obtained using consonant production.

• Journal of the Korean earth science society
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• v.37 no.6
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• pp.332-345
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• 2016

The columnar joints in Goheung are developed in three places of Yuju-san area, Palyeong-san and Yongbawi area. Vertical and fan-shaped columnar joints which have maximum width 100 m and maximum heigh 50 m are developed in the Yuju-san area Columnar joints are developed next to the road near the the Yuju-san and along the coast of Jijuk-do. Thick columnar joints of maximum width 1m are developed in the Paryeong-san area. Horizontal columnar joints of maximum width 50 cm at length of polygon side are developed on dyke in the Yongbawi area. The columnar joints show high rate of rectangles and pentagons in the number of polygons. The length of polygon side of columnar joints in study area ranges from 10 to 100 cm, and 20 cm among the range appears in high frequency. Columnar joints are developed vertically to the ground from the cooling surface in Yuju-san and Palyeong-san area. Columnar joints in Yongbawi area are developed vertically to the contact of country rocks. As a result, the columnar joints began cooling from the country rock contact. And columnar joints are developed vertically to contact surface. The rocks in columnar joints is rhyolitic welded tuff in Yuju-san and Palyeong-san area, dacite in Yongbawi area. In the acid volcanic rocks flow structure well developed. The white phenocryst mineral about 2 mm size by eye, is usually feldspar, and includes some quartz. The rate of $SiO_2$ is 70wt.% or more. It is the last stage of differentiation to calc-alkaline series. The columnar joints of the Yuju-san area are expected to be distributed along a band that extends to about 1km east of the stone pit.

• Geotechnical Engineering
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• v.1 no.2
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• pp.7-16
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• 1985

The behaviour of buried rigid pipe under embankment is analysed by a linear finite element program to study the influence of variation of the geometry of soil-conduit pipe system and elastic modulus of soil on the pipe response. The geometry of the system considered includes the thickness of pipe, the height of embankment, and the width arid the depth of trench. The normal contact pressure distribution around the pipe and the vertical load on the pipe are modelled by a multiple linear regression. And the vertical load on the pipe computed by Marston-Spangles Theory Is generally larger than that by finite element analysis. The settiement ratio in Marston-Spangler Theory is found to be variable for various for various of all factors mentioned above.