• Conservation Science in Museum
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• v.8
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• pp.49-69
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• 2007

This is about the scientific analysis of the 10 items of the gilt-bronze Panbul excavated from Anapji, Gyeongju. First, the composition of the Panbul was confirmed, using X-ray fluorescence spectrometer (XRF), and the patinas covering the surface of the Panbul were analyzed, using X-ray diffractometer (XRD). And the micro structures and gilt layer of the Panbul were investigated, using microscope and scanning electron microscope with energy dispersive spectrometer (SEM/EDS), and in order to investigate the internal conditions of the Panbul, X-radiography was conducted. As the result, it is found out that the material of the Panbul excavated from Anapji was the bronze of copper (86~95%) and tin (4~12%), and coated with gold. And cuprite (Cu₂O) was detected from red patina of the gilt-bronze Panbul, and chalcocite(Cu₂S) also was detected from the black patina. As the result of the observation of the micro structure through microscope, it is estimated that it was manufactured, using the wax molding method, and, judging from the fact that the thickness of gilt layer was not even, and that the groove had been filled, it was presumed that the amalgam coating method had been used, but some questions still remain, because mercury was not detected. Lastly, through the X-radiography, it was observed that the tiny round spots existed, which was presumed to have been generated during the casting.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.81.2-81.2
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• 2012

To fabricate a metal mold for injection molding, hot-embossing and imprinting process, mechanical machining, electro discharge machining (EDM), electrochemical machining (ECM), laser process and wet etching ($FeCl_3$ process) have been widely used. However it is hard to get precise structure with these processes. Electrochemical etching has been also employed to fabricate a micro structure in metal mold. A through mask electrochemical micro machining (TMEMM) is one of the electrochemical etching processes which can obtain finely precise structure. In this process, many parameters such as current density, process time, temperature of electrolyte and distance between electrodes should be controlled. Therefore, it is difficult to predict the result because it has low reliability and reproducibility. To improve it, we investigated this process numerically and experimentally. To search the relation between processing parameters and the results, we used finite element simulation and the commercial finite element method (FEM) software ANSYS was used to analyze the electric field. In this study, it was supposed that the anodic dissolution process is predicted depending on the current density which is one of major parameters with finite element method. In experiment, we used stainless steel (SS304) substrate with various sized square and circular array patterns as an anode and copper (Cu) plate as a cathode. A mixture of $H_2SO_4$, $H_3PO_4$ and DIW was used as an electrolyte. After electrochemical etching process, we compared the results of experiment and simulation. As a result, we got the current distribution in the electrolyte and line profile of current density of the patterns from simulation. And etching profile and surface morphologies were characterized by 3D-profiler(${\mu}$-surf, Nanofocus, Germany) and FE-SEM(S-4800, Hitachi, Japan) measurement. From comparison of these data, it was confirmed that current distribution and line profile of the patterns from simulation are similar to surface morphology and etching profile of the sample from the process, respectively. Then we concluded that current density is more concentrated at the edge of pattern and the depth of etched area is proportional to current density.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.223-228
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• 2016

In this study, we described a simple and facile method to generate uniform microwells poly(dimethyl siloxane) (PDMS) microstamps through micro-molding for efficient, rapid and reliable cell patterning of adipocyte differentiation. In contrast to the conventional methods, the microstamp technologies are low expensive, non-toxic, and using a small amount of solution. Recently, Orlistat known as tetrahydrolipstatin is a prescription drug designed to treat obesity which is used to aid in weight loss and help to reduce overweight obesity. Here, 3T3-L1 cells were treated under various concentration manners of Orlistat $0.2{\mu}M{\sim}5.0{\mu}M$. and it was confirmed maximum 26.5% inhibition activity compared to control. Thus, we elucidated this platform can be used for the real-time analyzing of cell proliferation, adipocyte differentiation for evaluation of anti-obesity agents on cell chip. Furthermore, we except that this platform technology designed here might be readily be expanded to discover a wider variety of anti-obesity agents.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.365-365
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• 2010

Similar to the superhydrophobic surfaces of lotus leaf, water strider leg is attributed to hierarchical structure of micro pillar and nano-hair coated with low surface energy materials, by which water strider can run and even jump on the water surface. In order to mimick its leg, many effort, especially, on the fabrication of nanohairs has been made using several methods such as a capillarity-driven molding and lithography using poly(urethane acrylate)(PUA). However most of those effort was not so effective to create the similar structure due to its difficulty in the fabrication of nanoscale hairy structures with hydrophobic surface. In this study, we have selected a low surface energy polymeric material of polytetrafluoroethylene (PTFE, or Teflon) assisted with surface modification of CF4 plasma treatment followed by hydrophobic surface coating with pre-cursor of hexamethyldisiloxane (HMDSO) using a plasma enhanced chemical vapor deposition (PE-CVD). It was found that the plasma energy and duration of CF4 treatment on PTFE polymer could control the aspect ratio of nano-hairy structure, which varying with high aspect ratio of more than 20 to 1, or height of over 1000nm but width of 50nm in average. The water contact angle on pristine PTFE surface was measured as approximately $115^{\circ}$. With nanostructures by CF4 plasma treatment and hydrophobic coating of HMDSO film, we made a superhydrophobic nano-hair structure with the wetting angle of over $160^{\circ}C$. This novel fabrication method of nanohairy structures has been applied not only on 2-D flat substrate but also on 3-D substrates like wire and cylinder, which is similarly mimicked the water strider's leg.

• Journal of the Korean Society of Radiology
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• v.12 no.6
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• pp.713-718
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• 2018

In many previous studies, monte carlo simulation is used to produce lead-free shielding sheet, and the possibility of radiation shielding capability and weight reduction is presented. But it is difficult to simulation for binder and micro-pores because of In fact it does not provide sufficient information necessary for the commercialization process. Therefore, in this paper, the results of radiation shielding capability corresponding to filling factor was presented by using the screen printing method to provide information on gel-paste required for the commercialization process. In this study, the geometric setup for evaluate of radiation shielding ability was designed to comply with IEC 61331-1:2014 and KS A 4025. In addition, radiation irradiation conditions were 100 kVp filtered with 2.0 mmAl total filtration was applied according to KS A 4021 standard. In this study, Pb $1270{\mu}m$, $BaSO_4$ $3035{\mu}m$, $Bi_2O_3$ $1849{\mu}m$ and $WO_3$ $2631{\mu}m$ were analyzed based on ten value layer. Additionally, the filling factor was analyzed as $BaSO_4$ 38.6%, $Bi_2O_3$ 27.1%, $WO_3$ 30.15%. However, in the case of applying low-temperature high-pressure molding in the future, it is expected that the radiation shielding capability can be sufficiently improved by reducing the porosity while increasing the filling factor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1139-1145
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• 2011

An automated anastomotic ring-pin system consisting of both the anastomotic ring-pin system and the coupler device has eliminated the drawbacks of the suture method. High density polyethylene (HDPE), a material with outstanding biocompatibility and injection molding capability, was used in the ring. SUS316 stainless steel, Ti-6Al-4Nb, Ti-6Al-4V, and unalloyed titanium were used in FEM simulations of the micropin. The authors categorized the microvascular anastomotic ring micropins into short neck (SN) and long neck (LN) groups in order to evaluate the effect of the micropin's fillet radius and neck length on the von Mises stress. The micropins were further divided into those with and without fillet. On the basis of the fillet radius rate (FRR), which represents the rate of change in the von Mises stress with respect to the availability and shape of the fillet, and the neck length rate (NLR), which represents the rate of change in the von Mises stress with respect to changes in the length of the neck within the fillet shape, it can be concluded that the SN-3 neck design is the most stable.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.5
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• pp.394-402
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• 2021

The entry of an aging society and the extension of human life expectancy, the increasing interest in women's social advancement and men's appearance, and the natural interest in K-culture through media media, while receiving worldwide attention, Focus on K-Bueaty. Recently, looking at the occupation of the medical tourism field, in the case of aesthetic medicine tourism such as molding and dermatology, it has gained popularity not only in Asia such as China and Japan, but also in North America and Europe. The first external confirmation of human aging is the wrinkles on the skin of the face. Clean, wrinkle-free, elastic and healthy skin is a desire of most people. Skin condition and condition such as focused ultrasonic stimulation (HIFU: High Intensity Focused Utrasound) and low frequency, high frequency (RF: Radio Frequency), galvanic therapy using microcurrent, cryotherapy using rapid cooling, etc. Depending on the method of management, the effect of the treatment differs depending on the output and the stimulation site, etc., even in the treatment of medical equipment and beauty equipment using the same mechanism. In this research, in order to develop invasive high-frequency dermatological devices using a large number of beauty medical devices and microneedles of beauty devices, the international standards IEC 60601-2 (standards for individual medical devices) and MFDS (Ministry of) We designed and developed a high-frequency output device in compliance with the high-frequency stimulation standard announced in the Food and Drug Safety (Ministry of Food and Drug Safety). The circuit design consists of an amplifier (AMP: Amplifier) using Class-A Topology and a power supply device using Half-Bridge Topology. As a result of measuring the developed high-frequency output device, an average efficiency of 63.86% was obtained, and the maximum output was measured at 116.7W and 50.67dBm.