• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.477-477
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• 2008

For more than three decades, the gate dielectrics in CMOS devices are $SiO_2$ because of its blocking properties of current in insulated gate FET channels. As the dimensions of feature size have been scaled down (width and the thickness is reduced down to 50 urn and 2 urn or less), gate leakage current is increased and reliability of $SiO_2$ is reduced. Many metal oxides such as $TiO_2$, $Ta_2O_4$, $SrTiO_3$, $Al_2O_3$, $HfO_2$ and $ZrO_2$ have been challenged for memory devices. These materials posses relatively high dielectric constant, but $HfO_2$ and $Al_2O_3$ did not provide sufficient advantages over $SiO_2$ or $Si_3N_4$ because of reaction with Si substrate. Recently, $HfO_2$ have been attracted attention because Hf forms the most stable oxide with the highest heat of formation. In addition, Hf can reduce the native oxide layer by creating $HfO_2$. However, new gate oxide candidates must satisfy a standard CMOS process. In order to fabricate high density memories with small feature size, the plasma etch process should be developed by well understanding and optimizing plasma behaviors. Therefore, it is necessary that the etch behavior of $HfO_2$ and plasma parameters are systematically investigated as functions of process parameters including gas mixing ratio, rf power, pressure and temperature to determine the mechanism of plasma induced damage. However, there is few studies on the the etch mechanism and the surface reactions in $BCl_3$ based plasma to etch $HfO_2$ thin films. In this work, the samples of $HfO_2$ were prepared on Si wafer with using atomic layer deposition. In our previous work, the maximum etch rate of $BCl_3$/Ar were obtained 20% $BCl_3$/ 80% Ar. Over 20% $BCl_3$ addition, the etch rate of $HfO_2$ decreased. The etching rate of $HfO_2$ and selectivity of $HfO_2$ to Si were investigated with using in inductively coupled plasma etching system (ICP) and $BCl_3/Cl_2$/Ar plasma. The change of volume densities of radical and atoms were monitored with using optical emission spectroscopy analysis (OES). The variations of components of etched surfaces for $HfO_2$ was investigated with using x-ray photo electron spectroscopy (XPS). In order to investigate the accumulation of etch by products during etch process, the exposed surface of $HfO_2$ in $BCl_3/Cl_2$/Ar plasma was compared with surface of as-doped $HfO_2$ and all the surfaces of samples were examined with field emission scanning electron microscopy and atomic force microscope (AFM).

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.3
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• pp.288-299
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• 2003

Statement of problem: Many kinds of post and core systems are in the market, but there are no clear selection criteria for them. Purpose: The purpose of this study was to compare the flexural strength and modulus of elasticity of core materials, and measure the bending strength of post systems made of a variety of materials. Material and Methods: The flexural strength and elastic modulus of thirteen kinds core buildup materials were measured on beams of specimens of $2.0{\times}2.0{\times}24{\pm}0.1mm$. Ten specimens per group were fabricated and loaded on an lnstron testing machine at a crosshead speed of 0.25mm/min. A test span of 20 mm was used. The failure loads were recorded and flexural strength calculated with the measured dimensions. The elastic modulus was calculated from the slopes of the linear portions of the stress-stram graphs. Also nine kinds commercially available prefabricated posts made of various materials with similar nominal diameters, approximately 1.25mm, were loaded in a three-point bend test until plastic deformation or failure occurred. Ten posts per group were tested and the obtained data were anaylzed with analysis of variance and compared with the Tukey multiple comparison tests. Results: Clearfil Photo Core and Luxacore had flexural strengths approaching amalgam, but its modulus of elasticity was only about 15% of that of amalgam. The strengths of the glass ionomer and resin modified glass ionomer were very low. The heat pressed glass ceramic core had a high elastic modulus but a relatively low flexural strength approximating that of the lower strength composite resin core materials. The stainless steel, zirconia and carbon fiber post exhibited high bending strengths. The glass fiber posts displayed strengths that were approximately half of the higher strength posts. Conclusion: When moderate amounts of coronal tooth structure are to be replaced by a post and core on an anterior tooth, a prefabricated post and high strength, high elastic modulus core may be suitable. CLINICAL IMPLICATIONS In this study several newly introduced post and core systems demonstrated satisfactory physical properties. However when the higher stress situation exists with only a minimal ferrule extension remaining a cast post and core or zirconia post and pressed core are desirable.

• Journal of Life Science
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• v.16 no.7 s.80
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• pp.1158-1163
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• 2006

Bisphenol A (BPA), 2,2-bis(4-hydroxyphenyl) propane, has been widely used as a monomer for production of epoxy resins and polycarbonate plastics, and final products of BPA include adhesives, protective coatings, paints, optical lens, building materials, compact disks and other electrical parts. Since BPA is a toxic chemical to elicit acute cell cytotoxicity and chronic endocrine disrupting activity, the degradation of BPA has been focused during last decades. To overcome the problem of photo-, and chemical-degradation of BPA, in this study, a bacterium that is able to biodegrade BPA, was isolated. The bacterium, isolated froln the soil of plastic factory, was identified as Acinetobacter calcoaceticus (strain BP-2) based on physiological and 16S rDNA sequencing analysis. A. calcoaceticus BP-2 was able to grow in the presence of $1140{\mu}g\;ml^{-1}$ BPA. Biodegradation experiments showed that BP-2 mineralized BPA via 4-hydroxybenzoic acid and 4-hydroxyacetophenone, and average degradation rate was $53.3{\mu}g\;ml^{-1}\;day^{-1}$ under optimal conditions (pH 7 and $30^{\circ}C$). In high density resting cell $(3.5g-dcw.1^{-1})$ experiments, the maximal degradation rate was increased to $89.7{\mu}g\;ml^{-1}\;h^{-1}$. Our results suggest that BP-2 has high potential as a catalyst for practical BPA bioremediation.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.407-413
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• 1997

The crystallized CuPc(copper phthalocyanine) film on a p-type <100> Si substrate is prepared at the substrate temperature of $300^{\circ}C$ by thermal evaporation. X -ray diffraction analysis showed the CuPc film to have a-axis oriented structure. For the measurement of photovoltaic characteristics of the CuPc/Si film and the Si substrate, a transverse current-voltage (I-V) curve is observed. In the dark, the Au/Si junction is shown to be ohmic contact. However, under illumination, a photovoltaic effect is not observed. The I-V curve in the dark indicates that the CuPc film on Si may form an ohmic contact. Since the CuPc film is a p-type semiconductor, the CuPc/p-Si junction has no barrier at the interface. Under illumination, the CuPc/Si junction shows a large photocurrent comparing with that of the wafer. The result indicates that the CuPc layer plays an important role in the photocarrier generation under red illumination (600 nm). The CuPc/Si film shows the photo voltaic characteristics with a short-circuit photocurrent ($J_{sc}$) of $4.29\;mA/cm^{2}$ and an open-circuit voltage ($V_{oc}$) of 12 mA.

• Analytical Science and Technology
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• v.29 no.4
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• pp.202-208
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• 2016

본 연구에서는 사료 첨가제로 이용되고 있는 유기산 7종(formic acid, malic acid, lactic acid, acetic acid, citric acid, fumaric acid, propionic acid)의 동시분석법 개발을 위한 연구를 실시하였다. 7종의 화합물은 표준물질의 Retention time과 UV spectra를 통해 구별하였고, 분석법 검증은 직선성, 민감성, 선택성, 정확성, 정밀성을 통하여 검증하였다. 그 결과로 LOD와 LOQ의 범위가 각각 43~26,755 μg/kg, 12-8,026 μg/kg으로 설정하였고, 평균 회수율이 79.3~95.2%로 우수하게 보였으며, intra-day, inter-day에 대한 전반적인 상대 표준 편차(%RSD)는 3.2% 미만으로 나타났다. 이와 같이 검증된 자료를 통해 유기산의 동시분석에 대한 직선성, 민감성, 선택성, 정확성 및 정밀성을 확인하였고, 높은 수준을 나타냄을 알 수 있었다. 이를 바탕으로 유기산이 검출되는 단미사료 46 가지를 분석에 적용하여 진행하였고, 정량과 동시분석 검출을 위한 방법은 RP-HPLC/UV 검출기를 이용하여 성공적으로 개발되었다. 따라서 본 연구결과를 바탕으로 하여 사료 중의 유기산의 분석이 신속하고 정확해졌을 뿐 아니라, 다른 종류의 사료 또한 이를 적용하여 효율적으로 이용할 수 있을 것으로 판단된다.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.4
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• pp.66-74
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• 2016

In what way is the urban landscape of North Korea used today, and what features do people prefer in the North Korean landscape? This study analyzed the characteristics of Pyongyang landscapes and their effects, based on an analysis of Western tourists motivation for tourism in North Korea and preferred enjoyment-seeking experiences. Using data from the tourist agency specializing in Western tourism in North Korea and a location based photo-sharing service, the study interprets the visual distinctiveness of Pyongyang landscape. The study concluded that widely known risk to travelers in North Korea is in fact an attraction, making people want to visit directly. However, this risk was mitigated in practical experience by the overall intermediation of the tourism agency and locals' conscious behavior to keep their distance from foreigners. Next, the scope of National ritual attributes was expanded to the locals' daily life as well as large-scale events such as mass games and military parades only if for national holidays. Also, the most preferred factors contributing to North Korean tourism were based on departure from routine through mobilization of the residents. This indicates the extension that the nature of North Korea as a theater state. The Pyongyang landscape represents a world politically isolated, people's congregated motion to display to the world, and people's lives hidden beneath a veil. These visualities fulfill the fantasy of Westerners regarding North Korea. Furthermore, these are superficial images that help create a basis to maintain the North Korea regime.

• KIISE Transactions on Computing Practices
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• v.21 no.10
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• pp.658-669
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• 2015

The paradigm of game development changes with technological trends. If the system can analyze and determine undefined inputs, users' input choices are not restricted. Therefore, game scenarios can have multifarious flows depending upon the user's input data. In this paper, we propose a method of including an output plan in the game system that is based on the user's input but is not restricted to predefined choices. We have implemented an experimental game on the Android platform by combining network communication and APIs. The game interface works as follows: first, the user's input data is transmitted to the server using HTTP protocol; then, the server carries out an analysis on the input data; and finally, the server returns the decision result to the game device. The game can provide users a scenario that corresponds to the decision results. In this paper, we used an image file for the user's input data format. The server calculates similarities between the user's image file and reference images obtained from the Naver Image Search API and then returns determination results. We have confirmed the value of integrating the game development framework with other computing technologies demonstrating the potential of the proposed methods for application to various future game interfaces.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.7-8
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• 2010

The surface conductive layer (SCL) of chemical vapor deposition (CVD) diamonds has attracting much interest. However, neither photoemission electron microscopic (PEEM) nor micro-spectroscopic (PEEMS) information is available so far. Since SCL retains in an ultra-high vacuum (UHV) condition, PEEM or PEEMS study will give an insight of SCL, which is the subject of the present study. The sample was made on a Ib-type HTHP diamond (001) substrate by non-doping CVD growthin a DC-plasma deposition chamber. The SCL properties of the sample in air were; a few tens K/Sq. in sheet resistance, ${\sim}180\;cm^2/vs$ in Hall mobility, ${\sim}2{\times}10^{12}/cm^2$ in carrier concentration. The root-square-mean surface roughness (Rq) of the sample was ~0.2nm as checked by AFM. A $2{\times}1$ LEED pattern and a sheet resistance of several hundreds K/Sq. in UHV were checked in a UHV chamber with an in-situ resist-meter [1]. The sample was then installed in a commercial PEEM/S apparatus (Omicron FOCUS IS-PEEM) which was composed of electro-static-lens optics together with an electron energy-analyzer. The presence of SCL was regularly monitored by measuring resistance between two electrodes (colloidal graphite) pasted on the two ends of sample surface. Figure 1 shows two PEEM images of a same area of the sample; a) is excited with a Hg-lamp and b) with a Xe-lamp. The maximum photon energy of the Hg-lamp is ~4.9 eV which is smaller that the band gap energy ($E_G=5.5\;eV$) of diamond and the maximum photon energy of the Xe-lamp is ~6.2 eV which is larger than $E_G$. The image that appear with the Hg-lamp can be due to photo-excitation to unoccupied states of the hydrogen-terminated negative electron affinity (NEA) diamond surface [2]. Secondary electron energy distribution of the white background of Figs.1a) and b) indeed shows that the whole surface is NEA except a large black dot on the upper center. However, Figs.1a) and 1b) show several features that are qualitatively different from each other. Some of the differences are the followings: the two main dark lines A and B in Fig.1b) are not at all obvious and the white lines B and C in Fig.1b) appear to be dark lines in Fig.1a). A PEEMS analysis of secondary electron energy distribution showed that all of the features A-D have negative electron affinity with marginal differences among them. These differences can be attributed to differences in the details of energy band bending underneath the surface present in SCL [3].

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.424-429
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• 2016

Globally, obesity has been recognized as a serious health problem. Recently, slimming foods for weight loss and maintenance were found to contain anti-obesity drugs, their analogues, and prohibited ingredients. To avoid inspections by the Government, structurally modified analogs have been continuously synthesized. For rapid determination of adulterated slimming products, we simultaneously analyzed 21 illegal compounds using liquid chromatography (LC) equipped with photo diode array, and LC coupled with tandem mass spectrometry. The validation of the method was performed with regard to selectivity, linearity, limit of detection, limit of quantification, precision, and accuracy. We purchased 128 samples from the Korean market and online sources in the year 2015. In 31 samples, 3 illegal compounds were detected as follows: 9.9-135.3 mg/g of sibutramine, 0.2-17.5 mg/g of yohimbine, and 1.8 mg/g of icariin. This simultaneous detection method might prove to be a simple and rapid analysis for monitoring illegal compounds in slimming foods.

• Korean Journal of Remote Sensing
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• v.35 no.5_2
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• pp.841-850
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• 2019

The purpose of this study is to strengthen the capability of rapid mapping for disaster through improving the positioning accuracy of mapping and fusion of multi-sensing point cloud data derived from Unmanned Aerial Vehicles (UAVs) and disaster investigation vehicle. The positioning accuracy was evaluated for two procedures of drone mapping with Agisoft PhotoScan: 1) general geo-referencing by self-calibration, 2) proposed geo-referencing with optimized camera model by using fixed accurate Interior Orientation Parameters (IOPs) derived from indoor camera calibration test and bundle adjustment. The analysis result of positioning accuracy showed that positioning RMS error was improved 2~3 m to 0.11~0.28 m in horizontal and 2.85 m to 0.45 m in vertical accuracy, respectively. In addition, proposed data fusion approach of multi-sensing point cloud with the constraints of the height showed that the point matching error was greatly reduced under about 0.07 m. Accordingly, our proposed data fusion approach will enable us to generate effectively and timelinessly ortho-imagery and high-resolution three dimensional geographic data for national disaster management in the future.