• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.314-314
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• 2013

Recently, flexibility is one of the hottest issues in the field of electronic devices. For flexible displays or solar cells, a development of transparent conductive electrodes (TCEs) with flexibility, bendability and foldability is an essential element. Hundreds of nanometers indium-tin-oxide (ITO) films have been widely used and commercialized as a transparent electrode, but their brittleness make them difficulty to apply flexible electronics. Many researchers have been studying for flexible TCEs such as a few layers of graphene sheets, carbon nanotube networks, conductive polymer films and combinations among them. Although gained flexibility, their transmittance and resistivity have not reached those of commercialized ITO films. Metal grids electrode cannot act as TCEs only, but they can be used to lower the resistance of TCEs with few losses of transmittance. However, the possibility of device shortage will be rise at the devices with metal grids because a surface flatness of TCEs may be deteriorated when metal grids are introduced using conventional methods. In our research, we have developed hybrid TCEs, which combined tens of nanometers ITO film and metal grids which are embedded in flexible substrate. They show $13{\Omega}$/${\Box}f$ sheet resistance with 94% of transmittance. Moreover, the sheet resistance was maintained up to 1 mm of bending radius. Also, we have verified that flexible organic light emitting diodes and organic solar cells with the TCEs showed similar performances compared to commercial ITO (on glass substrate) devices.

• Applied Microscopy
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• v.50
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• pp.21.1-21.3
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• 2020

Sample preparation is significantly important to the high-resolution transmission electron microscopy (HRTEM) characterization of nanomaterials. However, many general organic solvents can dissolve the necessary organic polymer support layer in TEM grid, which causes it difficult to obtain high-quality samples of oil-soluble nanomaterials. In this study, a new sample preparation method for oil-soluble nanomaterials has been developed by using the sublimable material as a transition layer. Experiments also show that there is no damage to TEM grids and high-quality HRTEM images can be obtained via this method. This approach paves the way to applicable HRTEM sample preparation of oil-soluble nanomaterials.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.4
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• pp.53-66
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• 2001

Modern art has had a great impact on the concepts and the formal attributes of modern landscape design. This study aimed at examining the origins of modern landscape design languages especially in relation to the influence of find art during the modernist age. The formal reductionism of Cubistic paintings finally lead to the formulation of Geometrical Abstractionism which became the basic formal model for ˝Regular Style˝; one of the representative modern landscape style. This Regular Style is mostly based on the formal structure of ´Grids´, which was developed by many landscape designer like Eckbo, Kley and Halprin. On the other hand, the ´Bio-morphic Form´ originally used in Surrealistic Art became the formal model for ˝Organic Style˝; the other representative modern landscape style, developed mostly by the landscape designers like Church, Burle-Mark and Bye. Thus, ´Grids´ and ´Bio-morphic Form´ became the dual icons of modern art and modern landscape design. Although these modern landscape design styles were ground breaking departure from the conventional formal/informal tradition and expanded possibilities in formal experimentations, They also produced several crucial limitations originated from the scientific reductionism and autonomous aesthetics of modern art, like the physical and cultural discontinuation from surrounding environments and the formal alienation from the real life world, which gave rise to the emergence of post-modern thinking of landscape design.

• Journal of Mechanical Science and Technology
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• v.19 no.6
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• pp.1329-1337
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• 2005

The OLED (Organic Light Emitting Diodes) display recently used for the information indicating device has many advantages over the LCD (Liquid Crystal Display), and its demand will be increased highly. The linear cell should be designed carefully considering the uniformity of thin film on the substrate. Its design needs to compute the temperature field analytically because the uniformity for the thin film thickness depends on the temperature distribution of the source (organic material). In the present study, the design of the linear cell will be modified or improved on the basis of the temperature profiles obtained for the simplified linear cell. The temperature distributions are numerically calculated through the STAR-CD program, and the grids are generated by means of the ICEM CFD program. As the results of the simplified linear cell, the temperature deviation was shown in the parabolic form among the both ends and the center of the source. In order to reduce the temperature deviation, the configuration of the rectangular ends of the crucible was modified to the circular type. In consequence, the uniform temperature is maintained in the range of about 90 percent length of the source. It is expected that the present methods and results on the temperature analysis can be very useful to manufacture the vapor deposition device.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.7-14
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• 2015

Recently, advances in nano-material researches have opened the door for various transparent conductive materials, which include carbon nanotube, graphene, Ag and Cu nanowire, and printable metal grids. Among them, Ag nanowires are particularly interesting to synthesize because bulk Ag exhibits the highest electrical conductivity among all metals. Here we reviewed recently-published research works introducing various devices from organic light emitting diode to tactile sensing devices, all of which are employing AgNW for a conducting material. They proposed methods to enhance the stretchability and reversibility of the transparent electrodes, and apply them to make various flexible and stretchable electronics. It is expected that Ag nanowires are applicable to a wide range of high-performance, low-cost, stretchable electronic devices.

• International Journal of High-Rise Buildings
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• v.4 no.2
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• pp.135-142
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• 2015

As the skyscraper matures as a building type, its role in actively connecting to, and reinforcing, major threads of urban fabric becomes increasingly more important. The creation of public spaces inside of and adjacent to tall buildings allows for significant additions to the public realm, facilitating better connections between varied uses, providing needed access to critical transportation functions. In this more integrated version of the tall building type, the density afforded by a vertical structure is complemented by strategically devised porosity of plan and section. This paper examines three major tower projects which exemplify a progressive approach to permeable design: the recently completed Jingan Kerry Centre in Shanghai, the Lotte Supertower in Seoul, now half completed, and the One Vanderbilt tower being proposed next to Grand Central Terminal in New York City. These projects suggest possibilities for innovative approaches to private development strategies, public planning processes, and architectural design.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.152-152
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• 2016

We studied the effect of the silver grid size on graphene transparent conducting films for flexible organic solar cells (OSCs). The silver grid was used an assistant layer of the graphene to reduce the sheet resistance of substrates. Silver grid with various graphene sizes for optimizing transmittance and sheet resistance of substrates were fabricated on polyethylene terephthalate (PET) substrates to form the hybrid films. The optimized grid geometry on the single layer graphene (SLG) was the grid dimension $200{\mu}m{\times}200{\mu}m{\times}50nm{\times}2{\mu}m$ (length ${\times}$ width ${\times}$ height ${\times}$ linewidth), where the sheet resistance was $55.73{\Omega}/square$ with the average transmittance of ~ 92.83 % at 550 nm. The properties of the OSCs fabricated using SLG with optimized silver grids on PET substrates show a short circuit current of $10.9mA/cm^2$, an open circuit voltage of 0.58 V, a fill factor of 60.8 %, and a power conversion efficiency (PCE) of 3.9 %. The PCE was improved about 91% than that of the OSCs using the SLG without the silver grid. These results demonstrate that the optimized grid geometry to the based on the graphene transparent electrodes contribute to improving the performance of OSCs.

• Korean journal of applied entomology
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• v.60 no.4
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• pp.417-422
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• 2021

This study aimed to provide information on the biodiversity of various arthropods living in paddy fields during the winter season by examining their incidence density. Insect collection was carried out by 50 × 50 cm grids of soil surface and plants from paddy fields, as well as from ridges between paddies, using a battery-powered aspirator. The total number of individuals collected from paddy fields and inter-paddy ridges was 41,197, most of belonged to the orders Collembola, Hemiptera, and Diptera. Arthropods showed similar appearance patterns in fields under both organic and conventional farming. However, a higher number of insects was collected in organic farms. The species diversity, species richness, and species evenness were all greater in inter-paddy ridges than in paddy fields, in a statistically significant manner (P < 0.05).

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1680-1688
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• 2004

The information indicating device plays an important part in the information times. Recently, the classical CRT (Cathod Ray Tube) display is getting transferred to the LCD (Liquid Crystal Display) one which is a kind of the FPDs (Flat Panel Displays). The OLED (Organic Light Emitting Diodes) display of the FPDs has many advantages for the low power consumption, the luminescence in itself, the light weight, the thin thickness, the wide view angle, the fast response and so on as compared with the LCD one. The OLED has lately attracted considerable attention as the next generation device for the information indicators. And also it has already been applied for the outside panel of a mobile phone, and its demand will be gradually increased in the various fields. It is manufactured by the vapor deposition method in the vacuum state, and the uniformity of thin film on the substrate depends on the temperature distribution in the point-cell source. This paper describes the basic concepts that are obtained to design the point-cell source using the computational temperature analysis. The grids are generated using the module of AUTOHEXA in the ICEM CFD program and the temperature distributions are numerically obtained using the STAR-CD program. The temperature profiles are calculated for four cases, i.e., the charge rate for the source in the crucible, the ratio of diameter to height of the crucible, the ratio of interval to height of the heating bands, and the geometry modification for the basic crucible. As a result, the blowout phenomenon can be shown when the charge rate for the source increases. The temperature variation in the radial direction is decreased as the ratio of diameter to height is decreased and it is suggested that the thin film thickness can be uniformed. In case of using one heating band, the blowout can be shown as the higher temperature distribution in the center part of the source, and the clogging can appear in the top end of the crucible in the lower temperature. The phenomena of both the blowout and the clogging in the modified crucible with the nozzle-diffuser can be prevented because the temperature in the upper part of the crucible is higher than that of other parts and the temperature variation in the radial direction becomes small.

• Fire Science and Engineering
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• v.28 no.1
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• pp.44-51
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• 2014

Smoke from fire is a mixture of combustion gases and particles which include micro-droplets formed from condensed organic vapors and carbonaceous agglomerates. The inhalation of smoke particles causes adverse health effects, and it is prerequisite for the hazard and risk analysis of the smoke particles to know how they behaviour in the respiratory tract. The characteristics of the absorption and adsorption of toxic gases and the amount and location of the particle deposition within the respiratory tract that determine the adverse health effects are related to the morphology and the size distribution of smoke particles. In the present work, as a preliminary study for the adverse health effects of smoke particles, the morphologies of the smoke particles from combustible materials were investigated for each fire stage: smouldering, well-ventilated flaming, small under-ventilated flaming, fully-developed under-ventilated fire. The steady-state tube furnace method given in ISO/TS 19700 was used for the generation of smoke particles. The fire stages were controlled by changing furnace temperature and equivalent ratio. The morphologies were analyzed by using Transmission Electron Microscope (Bio-TEM) by collecting the particles on TEM grids put on each stage of a cascade impactor.