• 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 the Korean institute of surface engineering
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• v.55 no.6
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• pp.398-402
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• 2022

Vacuum Insulation Panel (VIP) is an high energy efficient insulation system that facilitate slim but high insulation performance, based on based on a porous core material evacuated and encapsulated in a multi-barrier envelope. Although VIP has been on the market for decades now, it wasn't until recently that efforts have been initiated to propose a standard on aging testing. One of the issues regarding VIP is its durability and aging due to pressure and moisture dependent increase of the initial low thermal conductivity with time. It is hard to visually determine at an early stage. Recently, a method of analyzing the damage on the a material surface by applying image processing technology has been widely used. These techniques provide fast and accurate data with a non-destructive way. In this study, the surface VIP images were analyzed using the Harris corner detection algorithm. As a result, 171,333 corner points in the normal packaging were detected, whereas 32,895 of the defective packaging, which were less than the normal packaging. were detected. These results are considered to provide meaningful information for the determination of VIP condition.

• Journal of Periodontal and Implant Science
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• v.25 no.1
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• pp.121-132
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• 1995

Patients, who have gingival recession and complain of root sensitivity, or esthetic concerns, are candidates for root coverage. When free gingival grafting is used for complete root corverage, the results may not be entirely predictible unless the recession is shallow and narrow because a free gingival graft depends on collateral circulation from the lateral and apical parts of the recipient bed to survive over the avascular root. Various pedicle graft techniques can produce more esthetic results, but these procedures are only indicated when adequate donor tissues are available adjacent to the defect. This case report presents three cases for root coverage using the various connective tissue graft techniques. In the first case(Class III & IV), subepithelial connective tissue grafting was done and resulted in gingival coverage on the two-thirds of exposed root surface and blended with the adjacent tissue in color and texture. In the second case(Class I), connective tissue and partial thickness double pedicle graft resulted in complete coverage of denuded root surface. In the third case(Class I), recession was treated by supraperiosteal envelope technique. The root surface was covered completely and esthetically. Finally, the esthetics in both colors and tissue contours were acceptable to patients in all cases by the connective tissue grafting. However, in the case of the reduced interdental bone, the denuded root surfaces were hardly covered completely.

• BMB Reports
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• v.29 no.2
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• pp.180-182
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• 1996

One of the essential functions of virus surface proteins is the recognition of specific receptors on target cell membranes, and cellular receptors play an important role in viral pathogenesis. But the earliest steps of hepatitis B virus (HBV) infection, such as hepatocyte receptor interaction with the virus, are poorly understood. Previous work has suggested an important role of the preS1 region of HBV envelope protein in mediating viral binding to hepatocytes. Although hepatitis B virus (HBV) infection appears to be initiated by specific binding of virions to cell membrane structures via one or potentially several viral surface proteins, data showing the identification or isolation of the HBV receptor (s) are not yet available. The receptor-like proteins on the plasma membrane surface of HepG2 cells that bind to PreS1 were separated and identified using affinity chromatography, and the amino-terminal amino acid sequences of the receptor-like proteins were determined.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1639-1642
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• 1994

The severe conditions such as rated voltage of 800kV, gas pressure of $5kg/cm^2$ and rated lighting impulse withstand voltage of 2400kV were adopted for the design of spacers in the 800kV GIS to give a sufficient design margin. The design criteria on the maximum electric field strength of the center conductor and the insulator surface were established by considering the insulator surface characteristics, electrode area and surface effects in the unequal electric field strength of the given gap. The design parameters such as inter/outer envelope degree, thickness, inter/outer inserts, triple junction gap were determined by calculating the electric field using FLUX-2D program package and by referring to the published papers. The mechanical stress analysis was conducted on the feasible model spacers that showed good electric field distributions to confirm the sufficient mechanical design margin. The 800kV spacer designed as described above is now in the process of manufacturing.

• Journal of the Korean Society of Safety
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• v.36 no.2
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• pp.26-31
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• 2021

Buildings with glass curtain walls have become popular due to their appealing aesthetics and ability to let in natural light. However, light reflection from the glass surface is unavoidable in these buildings. In particular, the reflection of light from the glass envelope can create afterimage glare, a hazard to nearby drivers and pedestrians. Despite this potential danger, glare from buildings with curtain walls has not been well-studied. Hence, we analyzed the effect of light reflection on glare around a glass-enclosed skyscraper, depending on its surface reflectance. We investigated the potential hazard of glare to drivers using a commercially available software program. The results indicate that the direction of light reflection is distinctive when the incident angle of solar light increases. Moreover, this light reflection is high enough to induce an afterimage to drivers and pedestrians near the building. We found that keeping the reflectance of the building surface under 3% is required to minimize the afterimage hazard to drivers. Consequently, we recommend managing glass reflectance and installing additional traffic safety systems to reduce traffic accidents near curtain wall buildings.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1818-1826
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• 2014

Time-variant sea surface causes a forward scattering and Doppler spreading in received signal on underwater acoustic communication system. This results in time-varying amplitude, frequency and phase variation of the received signal. In such a way the channel coherence bandwidth and fading feature also change with time. Consequently, the system performance is degraded and high-speed coherent digital communication is disrupted. In this paper, quadrature phase shift keying (QPSK) performance is examined in two different sea surface conditions. The impact of sea surface scattering on performance is analyzed on basis of the channel impulse response and temporal coherence using linear frequency modulation (LFM) signal. The impulse response and the temporal coherence of the rough sea surface condition were more unstable and less than that of the calm sea surface condition, respectively. By relating these with time variant envelope, amplitude and phase of received signal, it was found that the bit error rate (BER) of QPSK are closely related to time variation of sea surface state.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1958-1967
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• 2004

This paper describes the method to rapidly fabricate the large-sized physical model with the envelope model size of more than 600 mm${\times}$ 600 mm${\times}$ 600 mm using two type semi-automatic VLM-ST processes in connection with the reverse engineering technology. The fabrication procedure of the large-sized solid shape is as follows: (1) Generation of STL data from 3D scan data using 3D scanner, (2) generation of shell-type STL data by Boolean operation, (3) division of shell-type STL data into several pieces by solid splitting, (4) generation of USL data for each piece with VLM-Slicer, (5) fabrication of each piece by cutting and stacking according to USL data using VLM-ST apparatus, (6) completion of a shell-type prototype by zigzag stacking and assembly for each piece, (7) completion of a 3D solid shape by foam backing, (8) surface finish of a completed 3D solid shape by coating and sanding. In order to examine the applicability of the proposed method, the miniature of the Mount Rushmore Memorial has been fabricated. The envelope model size of the miniature of the Mount Rushmore Memorial is 1,453 mm${\times}$ 760 mm${\times}$ 853 mm in size. From the result of the fabricated miniature of the Mount Rushmore Memorial, it has been shown that the method to fabricate the large object using two type semi-automatic VLM-ST processes in connection with the reverse engineering technology are very fast and efficient.

• Progress in Medical Physics
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• v.27 no.4
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• pp.272-276
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• 2016

To investigate the optimum x-ray tube design for the dental radiology, factors affecting x-ray beam characteristics such as tungsten target thickness and anode angle were evaluated. Another goal of the study was to addresses the anode heel effect and off-axis spectra for different target angles. MCNPX has been utilized to simulate the diagnostic x-ray tube with the aim of predicting optimum target angle and angular distribution of x-ray intensity around the x-ray target. For simulation of x-ray spectra, MCNPX was run in photon and electron using default values for PHYS:P and PHYS:E cards to enable full electron and photon transport. The x-ray tube consists of an evacuated 1 mm alumina envelope containing a tungsten anode embedded in a copper part. The envelope is encased in lead shield with an opening window. MCNPX simulations were run for x-ray tube potentials of 70 kV. A monoenergetic electron source at the distance of 2 cm from the anode surface was considered. The electron beam diameter was 0.3 mm striking on the focal spot. In this work, the optimum thickness of tungsten target was $3{\mu}m$ for the 70 kV electron potential. To determine the angle with the highest photon intensity per initial electron striking on the target, the x-ray intensity per initial electron was calculated for different tungsten target angles. The optimum anode angle based only on x-ray beam flatness was 35 degree. It should be mentioned that there is a considerable trade-off between anode angle which determines the focal spot size and geometric penumbra. The optimized thickness of a target material was calculated to maximize the x-ray intensity produced from a tungsten target materials for a 70 keV electron energy. Our results also showed that the anode angle has an influencing effect on heel effect and beam intensity across the beam.

• Journal of the Korean Solar Energy Society
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• v.35 no.4
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• pp.57-66
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• 2015

BIPV system not only produces electricity at building, but also acts as a material for building envelope. Thus, it can increase the economical efficiency of PV system by saving the cost for building materials. Bifacial solar cell can convert solar energy to electrical energy from both sides of the cell. In addition, it is designed as 3 busbar layout which is the same with ordinary mono-facial solar cells. Therefore, many of the module manufacturers can easily use the bifacial solar cells without changing their manufacturing equipments. Moreover, bifacial PV system has much potential in building application by utilizing glass-to-glass structure of PV module. However, the electrical generation of the bifacial PV module depends on the characteristics of the building surface which faces the module, as well as outdoor environment. Therefore, in order to apply the bifacial PV module to building envelope as BIPV system, its power generation characteristics are carefully evaluated. For this purpose this study focused on the electrical performance of the bifacial BIPV system through the comparative outdoor experiments. As a result, the power generation performance of the bifacial BIPV system was improved by up to 21% compared to that of the monofacial BIPV system. Therefore, it is claimed that the bifacial BIPV system can replace the conventional BIPV system to improve the PV power generation in buildings.