• Journal of the Korea Furniture Society
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• v.28 no.3
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• pp.207-223
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• 2017

Jeonju-Jang is the wood furniture that was made in Chonbuk Jeonju province during the Joseon Dynasty, and was used by middle-upper social classes. It has value as a local cultural heritage because it has unique characteristics in terms of the shape of the furniture, the metal ornament and various functions are integrated in accordance with user's requirements. Therefore, the purpose of this study is to define the structural characteristics of the Jeonju-Jang through case studies of 16 existing artifacts in order to preserve and inherit the value as local cultural resources. The conclusion is as follows. First, Jeonju-Jang in the late period of Joseon Dynasty that is made up of one board to the bottom with the binding of the board. and the front wall, the Juibyuckkan and the Meoruemkan are omitted or made small, so the structure of the surface is simple. There are three or four drawers under the Cheon pan(top plate). There are drawers and shelf inside the hinged door. In the case of a two-layer type, there is a Gaegumeong type door which has half of one side hinged. Second, Jeonju-Jang of the Japanese Ruling Era had a Juibyuckkan by frame binding and an increase in the number of Meoruemkan. and it had independent legs. The Cheon-pan(top plate) was more left and right than both sides. Third, in the late Joseon Dynasty period as a feature of the metal ornaments, cast iron and yellow brass were used as materials. In the Japanese Ruling Era, nickel was mainly used. Various patterns were engraved and the number increased, and it became gorgeous surface as a whole.

• Steel and Composite Structures
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• v.44 no.1
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• pp.65-79
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• 2022

The main goal of this paper is to study the vibration of damaged core laminated annular plates with FG face sheets based on a three-dimensional theory of elasticity. The structures are made of a damaged isotropic core and two external face sheets. These skins are strengthened at the nanoscale level by randomly oriented Carbon nanotubes (CNTs) and are reinforced at the microscale stage by oriented straight fibers. These reinforcing phases are included in a polymer matrix and a three-phase approach based on the Eshelby-Mori-Tanaka scheme and on the Halpin-Tsai approach, which is developed to compute the overall mechanical properties of the composite material. In this study the effect of microcracks on the vibrational characteristic of the sandwich plate is considered. In particular, the structures are made by an isotropic core that undergoes a progressive uniform damage, which is modeled as a decay of the mechanical properties expressed in terms of engineering constants. These defects are uniformly distributed and affect the central layer of the plates independently from the direction, this phenomenon is known as "isotropic damage" and it is fully described by a scalar parameter. Three complicated equations of motion for the sectorial plates under consideration are semi-analytically solved by using 2-D differential quadrature method. Using the 2-D differential quadrature method in the r- and z-directions, allows one to deal with sandwich annular plate with arbitrary thickness distribution of material properties and also to implement the effects of different boundary conditions of the structure efficiently and in an exact manner. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. The sandwich annular plate is assumed to have any arbitrary boundary conditions at the circular edges including simply supported, clamped and, free. Several parametric analyses are carried out to investigate the mechanical behavior of these multi-layered structures depending on the damage features, through-the-thickness distribution, and boundary conditions.

• Wind and Structures
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• v.13 no.1
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• pp.57-82
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• 2010

The 486m-long roof of Shenzhen Citizens Centre is one of the world's longest spatial lattice roof structures. A comprehensive numerical study of wind effects on the long-span structure is presented in this paper. The discretizing and synthesizing of random flow generation technique (DSRFG) recently proposed by two of the authors (Huang and Li 2008) was adopted to produce a spatially correlated turbulent inflow field for the simulation study. The distributions and characteristics of wind loads on the roof were numerically evaluated by Computational Fluid Dynamics (CFD) methods, in which Large Eddy Simulation (LES) and Reynolds Averaged Navier-Stokes Equations (RANS) Model were employed. The main objective of this study is to explore a useful approach for estimations of wind effects on complex curved roof by CFD techniques. In parallel with the numerical investigation, simultaneous pressure measurements on the entire roof were made in a boundary layer wind tunnel to determine mean, fluctuating and peak pressure coefficient distributions, and spectra, spatial correlation coefficients and probability characteristics of pressure fluctuations. Numerical results were then compared with these experimentally determined data for validating the numerical methods. The comparative study demonstrated that the LES integrated with the DSRFG technique could provide satisfactory prediction of wind effects on the long-span roof with complex shape, especially on separation zones along leading eaves where the worst negative wind-induced pressures commonly occur. The recommended LES and inflow turbulence generation technique as well as associated numerical treatments are useful for structural engineers to assess wind effects on a long-span roof at its design stage.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.391-392
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• 2012

Graphene is a perfectly two-dimensional (2D) atomic crystal which consists of sp2 bonded carbon atoms like a honeycomb lattice. With its unique structure, graphene provides outstanding electrical, mechanical, and optical properties, thus enabling wide variety of applications including a strong potential to extend the technology beyond the conventional Si based electronic materials. Currently, the widespread application for electrostatically switchable devices is limited by its characteristic of zero-energy gap and complex process in its synthesis. Several groups have investigated nanoribbon, strained, or nanomeshed graphenes to induce a band gap. Among various techniques to synthesize graphene, chemical vapor deposition (CVD) is suited to make relatively large scale growth of graphene layers. Direct growth of graphene on hexagonal boron nitride (h-BN) using CVD has gained much attention as the atomically smooth surface, relatively small lattice mismatch (~1.7％) of h-BN provides good quality graphene with high mobility. In addition, induced band gap of graphene on h-BN has been demonstrated to a meaningful value about ~0.5 eV.[1] In this paper, we report the synthesis of grpahene / h-BN bilayer in a chemical vapor deposition (CVD) process by controlling the gas flux ratio and deposition rate with temperature. The h-BN (99.99％) substrate, pure Ar as carrier gas, and $CH_4$ are used to grow graphene. The number of graphene layer grown on the h-BN tends to be proportional to growth time and $CH_4$ gas flow rate. Epitaxially grown graphene on h-BN are characterized by scanning electron microscopy, atomic force microscopy, and Raman spectroscopy.

• Journal of Information Display
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• v.7 no.4
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• pp.21-23
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• 2006

We developed a 4.5" 192${\times}$64 active matrix organic light-emitting diode display on a glass using organic thin-film transistor (OTFT) switching-arrays with two transistors and a capacitor in each sub-pixel. The OTFTs has bottom contact structure with a unique gate insulator and pentacene for the active layer. The width and length of the switching OTFT is 800${\mu}m$ and lO${\mu}m$ respectively and the driving OTFT has 1200${\mu}m$ channel width with the same channel length. On/off ratio, mobility, on-current of switching OTFT and on-current of driving OTFT were $10^6,0.3{\sim}0.5$ $cm^2$/V·sec, order of 10 ${\mu}A$ and over 100 ${\mu}A$, respectively. AMOLEDs composed of the OTFT switching arrays and OLEDs made using vacuum deposition method were fabricated and driven to make moving images, successfully.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.2 s.110
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• pp.38-46
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• 2005

Experimental work was carried out in order to produce a novel grade of ink-jet paper that has both high print-out quality and price competitiveness. Usually, silica and PVOH has been used for ink-jet paper to design the coating layer that has a hydrophilic and micro-porous structure. However, poor rheological characteristics and low productivity of the silica-PVOH system make the price of the ink-jet paper high. The main focus of this study was replacing the conventional silica (coating pigment) PVOH (binder) coating system with the new PCC (coating pigment) cationic starch (binder) coating system, and optimizing thecoating technology associated with PPC-cationic starch system. In this study, ink-jet print quality of PCC-coated papers was compared with that of silica-coated paper. Two types of PCC were used: conventional type and colloid type. It turned out that PCC C, a conventional coating pigment, has not given a desirable result: it showed high dot reproduction, but it gave low optical density. In spite of low dot reproduction, the qualities of PCC A were comparable or superior to those of silica in optical density, color reproduction, and the uniformity of printing surface. It was also shown that the problems that are happened when the dosage level of cationic starch was too low were varied with ink-type used in each printer. However, in the case of low binder level, the produced image was widely spread resulting fromtoo low optical density of images, or from the lack of bonding ability to set ink into coating surface.

• Korean Journal of Veterinary Research
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• v.37 no.1
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• pp.25-39
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• 1997

The morphology of the ductuli efferentes of the Korean native pheasants were observed in order to obtain a basic data for further studying reproductive physiology and other male genital organs. The mature (14-16 months after hatching) male pheasants were used in this study. The specimens from pheasants were collected on a monthly basis. The general morphological changes of the ductuli efferentes were observed with hematoxylineosin stain, and semithin section by light microscope. The ultrastructural changes of the ductuli efferentes were investigated with ultrathin section by transmission electron microscope. The results obtained are summarized as follows : 1. During the breeding season, the average height of ductuli efferentes epithelium was $23.45{\pm}2.34{\mu}m$ and was largely decreased by $17.85{\pm}2.01{\mu}m$ during the non-breeding season. The thickeness of interstitial tissue was comparatively increased during the non-breeding season. 2. During the breeding season, the epithelial cells of ductuli efferentes were well developed. During the non-breeding season, epithelial layer and lumen of ductuli efferentes, were markedley reduced compared with those of breeding season. 3. Morphological changes of the ductuli efferentes underwent periodic changes paralleling to the spermatogenic cycle. 4. At least two different cell types were identified in the epithelium of ductuli efferentes, namely non-ciliated and ciliated cells. 5. The ciliated cells possess many vesicles, slightly smaller than those of the non-ciliated cells. 6. The ciliated cells contained numerous mitochondria, smooth and rough endoplasmic reticulum, Golgi complex, lysosome, and oval nuclei. The non-ciliated cells had a irregular nuclei and a cytoplasm containing few organelles. 7. During the breeding season, a number of vesicles, rough and smooth endoplasmic reticulum, Golgi complex, and mitochondria were distinctively showed in the epithelial cells but in the non-breeding season only a few observed.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.631-631
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• 2013

Battery has major drawbacks including its size and life expectancy, and environmental problem. As an alternative, energy harvesting is emerging as a potential solution to replace battery along with more energy-efficient IT devices. The idea of harnessing energy from our living environment is sustainable, semi-permanent, and eco-friendly. Also, unlike battery, energy harvester does not require much space to store energy. Therefore, energy harvesting can provide a better source of power for small, portable, and wireless devices. Among various ways of harvesting energy from our surroundings, triboelectricity is chosen due to its potential to be miniaturized, and efficient. Triboelectric effect occurs as two different materials with different polarity of charge separation come into contact through friction, and then become separated so that electric potential difference is achieved. In this research, such characteristic of triboelectricity is used as a way to convert ambient mechanical energy into electric energy.Series of recent researches have shown promising results that the triboelectric energy harvester can be simple and cost effective. However, sufficient electricity level required to operate mobile devices has not yet been achieved.In this research, our group focuses on the design and optimization of triboelectric energy harvesting device to enhance its output. By using maskless lithography to pattern Kapton film and silicon substrate, which is used as a mold for PDMS thin layer, and sputtering metal electrodes on each side, we fabricate and demonstrate different designs of triboelectric energy harvester that utilizes the contact electrification between a polymer thin film and a metal thin foil. In order to achieve optimized result, the output voltage and current are measured under diverse conditions, which include different surface structure and pattern, material, and the gap between layers.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_1
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• pp.177-184
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• 2022

The automatic defect sorting function of machinery parts is being introduced to the automation of the manufacturing process. In the final stage of automation of the manufacturing process, it is necessary to apply computer vision rather than human visual judgment to determine whether there is a defect. In this paper, we introduce a deep learning method to improve the classification performance of typical mechanical parts, such as welding parts, galvanized round plugs, and electro galvanized nuts, based on the results of experiments. In the case of poor welding, the method to further increase the depth of layer of the basic deep learning model was effective, and in the case of a circular plug, the surrounding data outside the defective target area affected it, so it could be solved through an appropriate pre-processing technique. Finally, in the case of a nut plated with zinc, since it receives data from multiple cameras due to its three-dimensional structure, it is greatly affected by lighting and has a problem in that it also affects the background image. To solve this problem, methods such as two-dimensional connectivity were applied in the object segmentation preprocessing process. Although the experiments suggested that the proposed methods are effective, most of the provided good/defective images data sets are relatively small, which may cause a learning balance problem of the deep learning model, so we plan to secure more data in the future.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.1-7
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• 2023

The advent of deep learning technologies has led to the development of various medical applications, making healthcare services more convenient and effective. Among these applications, heart rate estimation is considered a vital method for assessing an individual's health. Traditional methods, such as photoplethysmography through smart watches, have been widely used but are invasive and require additional hardware. Recent advancements allow for contactless heart rate estimation through facial image analysis, providing a more hygienic and convenient approach. In this paper, we propose a lightweight methodology capable of accurately estimating heart rate in mobile environments, using a specialized 2-channel network structure based on 2D convolution. Our method considers both subtle facial movements and color changes resulting from blood flow and muscle contractions. The approach comprises two major components: an Encoder for analyzing image features and a regression layer for evaluating Blood Volume Pulse. By incorporating both features simultaneously our methodology delivers more accurate results even in computing environments with limited resources. The proposed approach is expected to offer a more efficient way to monitor heart rate without invasive technology, particularly well-suited for mobile devices.