• Journal of the Society of Naval Architects of Korea
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• v.55 no.1
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• pp.66-74
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• 2018

In order to evaluate the precision degree of the blocks on the dock, the shipyards recently started to use the point cloud approaches using the 3D scanners. However, they hesitate to use it due to the limited time, cost, and elaborative effects for the post-works. Although it is somewhat traditional instead, they have still used the electro-optical wave devices which have a characteristic of having less dense point set (usually 1 point per meter) around the contact section of two blocks. This paper tried to expand the usage of point sets. Our approach can estimate the rework time to weld between the Pre-Erected(PE) Block and Erected(ER) block as well as the precision of block construction. In detail, two algorithms were applied to increase the efficiency of estimation process. The first one is K-mean clustering algorithm which is used to separate only the related contact point set from others not related with welding sections. The second one is the Concave hull algorithm which also separates the inner point of the contact section used for the delayed outfitting and stiffeners section, and constructs the concave outline of contact section as the primary objects to estimate the rework time of welding. The main purpose of this paper is that the rework cost for welding is able to be obtained easily and precisely with the defective point set. The point set on the blocks' outline are challenging to get the approximated mathematical curves, owing to the lots of orthogonal parts and lack of number of point. To solve this problems we compared the Radial based function-Multi-Layer(RBF-ML) and Akima interpolation method. Collecting the proposed methods, the paper suggested the noble point matching method for minimizing the rework time of block-welding on the dock, differently the previous approach which had paid the attention of only the degree of accuracy.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.112-119
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• 2015

Photoacoustic microscopy is capable of providing high-resolution molecular images, and its spatial resolution is typically determined by ultrasonic transducers used to receive the photoacoustic signals. Therefore, ultrasonic transducers for photoacoustic microscopy (PAM) should have a high operating frequency, broad bandwidth, and high signal-reception efficiency. Polyvinylidene fluoride (PVDF) is a suitable material. To take full advantage of this material, the selection of the backing material is crucial, as it influences the center frequency and bandwidth of the transducer. Therefore, we experimentally determined the most suitable backing material among EPO-TEK 301, E-Solder 3022, and RTV. For this, three PVDF high-frequency single-element transducers were fabricated with each backing material. The center frequency and -6 dB bandwidth of each transducer were ascertained by a pulse-echo test. The spatial resolution of each transducer was examined using wire-target images. The experimental results indicated that EPO-TEK 301 is the most suitable backing material for a PAM transducer. This material provides the highest signal magnitude and a reasonable bandwidth because a large portion of the energy propagates toward the front medium, and the PVDF resonates in the half-wave mode.

• Economic and Environmental Geology
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• v.15 no.1
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• pp.41-47
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• 1982

Typical stratigraphic sequences of Paleozoic form the Baegunsan Syncline (equal to Hambaeg Syncline) and Taebaegsan Group is the basement in the southern part of Kangweon Province. Deformation pattern depends on their stratigraphic site and their internal properties. In the biotite schists and meta-sandstones of Pre-Cambrian sequences, flow folds and ptygmatic folds are developed, and high strain deformation is pervasive. Deformational patterns of Cambro-Ordovician are variable because of their various formations. Fracturing is pervasive in the Jangsan Quartzite and Daegi and Maggol Limestone. Welldeveloped slaty cleavage and angular folds of kink and chevron types are the prevailing structures of pelitic rocks. The most characteristic feature of limestone alternated with argillite is the "Compositional cleavage (Author's proposal)" known as the "Worm-eatern" structures. It was known that this structures have a sedimentary origin. But their preferred orienation of long axis of erosional lime holes, originated from tectonic deformation of folding. And this structures have the same character as the axial plane cleavages. Fracturing and long wave concentric folds are dominant characters of the Upper Paleozic sequences. In this area, two folds are superimposed. Field studying and analysis of structures show that the cross-folds of NS-direction are pervasive and were deformed by the EW-directional Baegunsan Syncline. The cross-folding is the major and penetrative deformation and prior to Baegunsan Syncline.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.4
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• pp.428-435
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• 2004

With the rapid and wide-spread use of cellular telephones much attention has been focussed on propagation in the urban area crowed with buildings and houses. It is often surrounded by hills, forests, and mountains. The importance of surface scattering intereference between transmitters and receivers on the rough surfaces has been interested and investigated. Therefore, a prediction method is necessary to estimate the influence of rough surfaces on microwave radio propagation. Moreover, most of the mobile communications are performed based on the digital communication system rather than the analog one. In this case, we must pay more careful attention to the signal delay caused by the phase delay due to the multi-path propagation. In this paper we have analyzed numerically scattering of electromagnetic waves from building walls by using FVTD(Finite Volume Time Domain) method. We consider three different types of rough surfaces such as periodic, random, and composite structures. We calculate the bistatic normalized radar cross section (NRCS) for horizontal and vertical polarization, and we take account of the conventional optical reflection which corresponds to the n-th Bragg reflection for periodic structures. In addition, we investigated what conditions are needed in order to be able to ignore the higher order Bragg reflection for the periodic structures.

• Sleep Medicine and Psychophysiology
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• v.14 no.1
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• pp.42-48
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• 2007

Introduction: Detrended fluctuation analysis (DFA) is used as a way of studying nonlinearity of EEG. In this study, DFA is applied on sleep EEG of normal subjects to look into its nonlinearity in terms of EEG channels and sleep stages. Method: Twelve healthy young subjects (age：$23.8{\pm}2.5$ years old, male：female=7：5) have undergone nocturnal polysomnography (nPSG). EEG from nPSG was classified in terms of its channels and sleep stages and was analyzed by DFA. Scaling exponents (SEs) yielded by DFA were compared using linear mixed model analysis. Results: Scaling exponents (SEs) of sleep EEG were distributed around 1 showing long term temporal correlation and self-similarity. SE of C3 channel was bigger than that of O1 channel. As sleep stage progressed from stage 1 to slow wave sleep, SE increased accordingly. SE of stage REM sleep did not show significant difference when compared with that of stage 1 sleep. Conclusion: SEs of Normal sleep EEG showed nonlinear characteristic with scale-free fluctuation, long-range temporal correlation, self-similarity and self-organized criticality. SE from DFA differentiated sleep stages and EEG channels. It can be a useful tool in the research with sleep EEG.

• Journal of the Korean GEO-environmental Society
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• v.21 no.1
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• pp.5-12
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• 2020

Vibration propagated from seismic sources has damping according to distance and amplification and reduction characteristic in different regions according to topography and geological structure. The vibration propagated from the seismic source to the bedrock is largely affected by the damping according to the separation distance, which can be simply estimated through the damping equation. However, it is important to grasp geological information by location because vibration estimation transmitted to the surface are affected by the natural period of the soil located above the bedrock. Geotechnical investigation data are needed to estimate the seismic intensity based on geological information. If there is no Vs profile, the standard penetration tests are mainly used to determine the soil parameters. The Integrated DB Center of National Geotechnical Information manages the geotechnical survey data performed on the domestic ground, and there is the standard penetration test information of 400,000 holes. In this study, the possibility of quantitation the amplification coefficient for each region was examined to calculated the physical interactive seismic intensity based on geotechnical information. At this time, the shear wave column diagram was generated from the SPT-N value and ground response analysis was performed in the target area. The site coefficients for each zone and the seismic intensity distribution for the seismic motion present a significant difference according to the analysis method and the regional setting.

• Journal of Sensor Science and Technology
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• v.19 no.5
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• pp.361-368
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• 2010

ACROSS device, which is composed of an implantable microphone, a signal processor, and a vibrating transducer, is a fullyimplantable middle ear hearing device(F-IMEHD) for the recovery of patients with hearing loss. And since a microphone is implanted under skin and tissue at the temporal bones, the amplitude of the sound wave is attenuated by absorption and scattering. And the vibrating transducer attached to the ossicular chain caused also the different displacement from characteristic of the stapes. For the gain control of auditory signals, most of implantable hearing devices with the digital audio signal processor still apply to fitting rules of conventional hearing aid without regard to the effect of the implanted microphone and the vibrating transducer. So it should be taken into account the effect of the implantable microphone and the vibrating transducer to use the conventional audio fitting rule. The aim of this study was to measure gain characteristics caused by the implanted microphone and the vibrating transducer attached to the ossicle chains for the gain compensation of ACROSS device. Differential floating mass transducers (DFMT) of ACROSS device were clipped on four cadaver temporal bones. And after placing the DFMT on them, displacements of the ossicle chain with the DFMT operated by 1 $mA_{peak}$ current was measured using laser Doppler vibrometer. And the sensitivity of microphones under the sampled pig skin and the skin of 3 rat back were measured by stimulus of pure tones in frequency from 0.1 to 8.9 kHz. And we confirmed that the microphone implanted under skin showed poorer frequency response in the acoustic high-frequency band than it in the low- to mid- frequency band, and the resonant frequency of the stapes vibration was changed by attaching the DFMT on the incus, the displacement of the DFMT driven with 1 $mA_{rms}$ was higher by the amount of about 20 dB than that of cadaver's stapes driven by the sound presssure of 94 dB SPL in resonance frequency range.

• Journal of the Korean Child Neurology Society
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• v.26 no.4
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• pp.272-275
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• 2018

KBG syndrome is a rare neurodevelopmental disorder characterized by intellectual disability, skeletal anomalies, short stature, craniofacial dysmorphism, and macrodontia. ANKRD11 gene mutation and 16q24.3 microdeletion have been reported to cause KBG syndrome. Here, we report two patients with ANKRD11 mutations who initially presented with neurologic symptoms such as developmental delay and seizures. Patient 1 was a 23-month-old boy who presented with a global developmental delay. Language delay was the most dominant feature. He had hypertelorism, hearing impairment, and behavior problems characterized as hyperactivity. A c.1903_1907delAAACA (p.Lys635GInfsTer26) mutation in ANKRD11 was identified with diagnostic exome sequencing. Patient 2 was a 14-month-old boy with developmental delay and seizure. He also had atrial septum defect, and ventricular septal defect. Generalized tonic seizures began at the age of 8 months. Electroencephalography showed generalized sharp and slow wave pattern. Seizures did not respond to antiepileptic drugs. A loss of function mutation c.5350_5351delTC (p.ser1784HisfsTer12) in ANKRD11 was identified with diagnostic exome sequencing. In both cases, characteristic features of KBG syndrome such as short stature or macrodontia, were absent, and they visited the hospital due to neurological symptoms. These findings suggest that more patients with mild phenotypes of KBG syndrome are being recognized with advances in diagnostic exome sequencing genetic technologies.

• International journal of advanced smart convergence
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• v.10 no.4
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• pp.241-255
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• 2021

The human auricle is the first part to receive sound from the outside. In this part, the frequency range of human recognizable form is divided and organized. In this study, we propose modeling by applying a single sound source to the surface of the human auricle. This means that when the sound pressure of a low frequency (low frequency) sound enters the pinna, the impedance felt at the tip of a part of the non-linear surface of the pinna is mainly due to the tensile force at the end of the part of the non-linear surface of the pinna. By expressing the situation of moving at a very small speed, the characteristic impedance of the pinna was confirmed to be negative infinity, and it was also confirmed that the speed at the tip of a part of the non-linear surface of the pinna was 0 in the anti-resonance state. It was found that the wave propagation phenomenon that determines the characteristics of the filter is determined by how large the wavelength, kL, is compared to the length of the tip of a part of the non-straight surface of the pinna. Humans first receive sounds from outside through their ears. The auricle is non-linear and has a curved shape, and it is known that it analyzes frequencies while receiving external sounds. The human ear has an audible frequency range of 20Hz - 20,000Hz. Through the study, we applied the characteristics of the notch filter to hypothesize that the human audible frequency range is separated from the auricle, and applied filter theory to analyze it, and as a result, meaningful results were obtained. The curved part and the inner part of the auricle function as a trumpet, collecting sounds, and at the same time amplifying the weak sound of a specific band. The point was found and the shape of the envelope detected in the auricle was found. Selectivity for selecting sounds coming from the outside is the formula of the pinna that implements the function of Q. The function of distinguishing human-recognizable sound from the pinna from low to high through frequency analysis is performed in the pinna, and the 2-3kHz area, where human hearing threshold is the most sensitive, is also the acoustic impedance of the most recessed area of the pinna. It can be seen that starting from.

• Journal of Conservation Science
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• v.35 no.3
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• pp.237-244
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• 2019

In this study, we applied terahertz imaging technology to three Korean modern oil paintings ('Boy,' 'Girl,' and 'Hyehwadong Landscape'); investigated the types of inner layer information in the pictures that can be extracted with terahertz imaging technology; and analyzed the conditions for extracting them. The biggest problem in the terahertz imaging analysis we encountered was the image distortion caused by the change of the distance between the target surface and the terahertz detector, depending on the surface curvature of the target paintings. We then developed a 'working distance maintaining device' to solve this problem. As a result, the terahertz imaging technique was used to identify the base material characteristics and any patterns of damage inside, and presented the optimal conditions for identifying each characteristic. In addition, it was useful to employ the terahertz frequency-division image to check the characteristics of the background materials. To confirm coloring techniques such as brush strokes, it is effective to compare the maximum reflection peak image with the cross-section image; and to detect damage information inside the paintings that cannot be observed on the surface, to compare the cross-section image with the frequency-division image. On the other hand, according to the terahertz imaging analysis of the oil paintings, the internal structural damage marks of 'Boy' and 'Girl' were confirmed, and the artist's painting style was confirmed in 'Hyehwadong Landscape.' The above results are expected to be useful for the analysis and diagnosis of Korean modern oil paintings for their preservation.