• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.547-553
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• 2017

This study focused on the difference of photocatalytic performance by the incorporation of Pd into the $TiO_2$ framework and suggested five different catalysts composed of $TiO_2$ and x mol% $Pd-TiO_2$ (x = 0.25, 0.5, 0.75, and 1.0). A typical sol-gel method was used to synthesize catalysts, and the phenol photodegradation performance of each catalysts was evaluated. The physicochemical and optical properties of catalysts were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), ultraviolet/visible spectroscopy (UV/Vis), photoluminescence spectroscopy (PL), and photocurrent measurements. With the addition of Pd ions, the band gap of catalysts was shortened and the charge separation between photogenerated electrons and holes easily also occurred. As a result, the phenol photo-destruction performance over 0.75 mol% $Pd-TiO_2$ catalyst was 3 times higher than that of pure $TiO_2$. This is believed to be due to Pd ions acted as an electron capturing function during photocatalysis.

• Journal of Information Management
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• v.42 no.3
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• pp.71-94
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• 2011

Query by visual example is the principal query paradigm for expressing queries in a content-based image retrieval environment. Query by image and query by sketch have long been purported as being viable methods of query formulation yet there is little empirical evidence to support their efficacy in facilitating query formulation. The ability of the searcher to express their information problem to an information retrieval system is fundamental to the retrieval process. The aim of this research was to investigate the query by image and query by sketch methods in supporting a range of information problems through a usability experiment in order to contribute to the gap in knowledge regarding the relationship between searchers' information problems and the query methods required to support efficient and effective visual query formulation. The results of the experiment suggest that query by image is a viable approach to visual query formulation. In contrast, the results strongly suggest that there is a significant mismatch between the searchers information problems and the expressive power of the query by sketch paradigm in supporting visual query formulation. The results of a usability experiment focusing on efficiency (time), effectiveness (errors) and user satisfaction show that there was a significant difference, p<0.001, between the two query methods on all three measures: time (Z=-3.597, p<0.001), errors (Z=-3.317, p<0.001), and satisfaction (Z=-10.223, p<0.001). The results also show that there was a significant difference in participants perceived usefulness of the query tools Z=-4.672, p<0.001.

• Restorative Dentistry and Endodontics
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• v.30 no.3
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• pp.204-214
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• 2005

This study compared the microtensile bond strength (${\mu}$TBS) and microscopic change of two 2-step and two 1-step self-etching adhesives to dentin according to storage times in distilled water. Occlusal dentin was exposed in 48 human molars. They were divided to four groups by different adhesives: SE Bond group (Clearfil SE Bond), AdheSE group (AdheSE). Adper group (Adper Prompt L-Pop), and Xeno group (Xeno III) . Each group was stored in 37$^{\circ}C$ distilled water for 1, 15, and 30 days. Resin-bonded specimens were sectioned into beams and subjected to ${\mu}$TBS testing with a crosshead speed of 1 mm/minute. For SEM observation, one specimen was selected and sectioned in each group after each stroage time. Resin-dentin interface was observed under FE-SEM. In all storage times, mean ${\mu}$TBS of SE group was significantly higher than those of other groups (p < 0.05). There was no significant difference between mean ${\mu}$TBS of SE group and AdheSE group among all storage times, but significant difference between 1- and 30-day storage in mean y${\mu}$TBS of Adper group and Xeno group (p > 0.05). For 1-and 15-day storage, all groups showed the close adaptation between resin-dentin interfaces. For 30-day storage, resin-dentin interfaces showed wide gap in Adper group and separate pattern in Xeno III group.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.239-248
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• 2006

In this paper, the cryogenically cooled low noise amplifier module for radio telescope receiver front-end using pHE-MT MMIC is designed and fabricated. In the selection of MMIC, the MMIC fabricated with the pHEMTS providing successful cryogenic operation are chosen. They are mounted in the housing using the thin film substrate. In the design of the housing, the absorber and the elimination of the gap between the carrier and the housing as well removed the unnecessary oscillations by its structure. The mismatch is improved by ribbon-tuning to provide the best performance at room temperature. The fabricated module shows the gain of $35dB{\pm}1dB$ and the noise figure of $2.37{\sim}2.57dB$ at room temperature over $21.5{\sim}23.5GHz$. In the cryogenic temperature of $15^{\circ}K$ cooled by He gas, the measured gain was above 35 dB and flatness ${\pm}2dB$ and the noise temperatures of $28{\sim}37^{\circ}K$.

• Journal of dental hygiene science
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• v.4 no.1
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• pp.39-44
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• 2004

The primary purpose of this report is to investigate the index of dental caries experiences and the state of oral hygiene for the children with mental retardation, cerebral palsy, and autism. In order to get those things we investigated 99 students that ages from 8 to 13 in three special schools (which are the school for the children with mental retardation, physical difficulties, emotional disturbance). Then collected the statistics and examined if there were some regardful differences among each type. (1) The investigation shows that there is no regardful differences among them in statistice. However, the averages of their dental caries experience have a little gap. The average of the children with mental retardation group is the highest and the autistic children group is the lowest, as we can see the facts of 4.70 for group of children with mental retardation, 4.58 for group of children with cerebral palsy, 3.67 for group of autistic children, children with mental retardation group is severe, autistic children group is few. (2) The conclusion from research of oral hygiene among each type, statistically regardful differences were revealed (p<0.05). It shows children with cerebral palsy is on worst state, children with mental retardation is on next state, autistic children is on best state by compare for averages among each type, 32.30 for group of children with mental retardation 35.00 for group of children with cerebral palsy, 27.79 for autistic children.

• Solar Energy
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• v.12 no.3
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• pp.10-20
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• 1992

In this experiment, photochemical reaction has been applied to destroy TCE in water phase. The main target of this work is to investigate the technical feasibility of large scale of solar detoxification reactor for water treatment. The results have revealed that solar detoxification utilizing photon energy from the sun is the most attractive process to decompose organic toxins in water phase at room temperature. The detailed results from this work are as follows; (1) The highest conversion ratio of TCE was obtained by using $TiO_2$, annatase as a photocatalyst among $TiO_2$ anatase, $TiO_2$ rutile and $V_2O_5$ under the same experimental condition. The anatase crystal structure was confirmed with XRD analysis, and its surface area was 7.748 $m^2/g$ from the BET-$N_2$ measurement (2) 0.1 wt% of $TiO_2$ anatase has been adopted as optimal quantity for batch slurry reactor at this experimental conditions. (3) The effect of hydrogen peroxide on the conversion of TCE was investigated. Its optimal quantity was 0.06 vol. % under this experimental conditions. (4) The effect of oxygen on the conversion of TCE also was studied by controlling the head space in photoreactor. Results indicated that sufficient amount of oxygen should be supplied to accomplish the highest conversion rate of TCE in water phase.

• Membrane Journal
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• v.20 no.4
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• pp.304-311
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• 2010

In this study, loose RO hollow fiber membranes using CTA polymer were prepared by phase inversion method and their water purification properties were tested. 1,4-dioxane and LiCl was used as a skin layer formation agent and pore formation agent, respectively. Water flux, salt rejection, chlorine resistance, MWCO and membrane morphology were evaluated as a function of the dope composition. When the membrane prepared using the dope solution of CTA/NMP/1,4-dioxane = 18/72/10 (wt%) with air gap of 30 cm, it shows improved RO performance such as $20.5L/m^2hr$ of water flux, 60% of NaCl rejection, 10,000 ppm/hr of chlorine-resistance and around 5,000 Da of MWCO.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.163-168
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• 2015

In this paper, 433/865MHz dual band antenna is proposed by using IFA structure of a PCB antenna, the performance was improved by changing of the space between the feed point and short strip, varying the gap between the radiator and the ground plane and adding the branch line in the proposed antenna. To confirm the characteristics of the antenna parameters, HFSS from ANSYS Inc. was used for the analysis. RFID frequency band of ISO-18000-7 is 433MHz and EU-RFID frequency band of ISO-18000-6 is from 865.5 to 867.5MHz. Each of the 433/865MHz bandwidth of the proposed antenna is 5.2MHz and 18.2MHz. The maximum 433MHz antenna gain is -5.74dBi, the maximum 865MHz antenna gain is -3.36dBi. The Jig size of the proposed antenna is $60{\times}44{\times}1mm$ and the size of the antenna area $44{\times}21mm$. The results proved the possibility of the practical use on 433/865MHz by using the IFA structure that came from comparing and analyzing the measured and simulated data of the antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1059-1068
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• 2016

This paper proposes slow wave structure(SWS) utilized to increase antenna gain of printed dipole antenna(PDA) and to suppress sidelobe level simultaneously, and makes sure of electrical characteristics of the antenna according to parameter variations of components of the slow wave structure. The printed slow wave structure which is composed of a dielectric substrate and a metal rods array is located on excited direction of the PDA, affecting the radiation pattern and its intensity. Parasitic elements of the metal rods are arrayed in narrow consistent gap and have a tendency to gradually decrease in length. In this paper, array interval, element length, and taper angle are selected as the parameter of the parasitic element that effects radiation characteristics. Magnitude and phase distribution of the electrical field are observed and analyzed for each parameter variations. On the basis of these results, while the radiation pattern is analyzed, array methods of parasitic elements of the SWS for high gain characteristics are provided. The proposed antenna is designed to be operated at the Wifi band(5.15~5.85 GHz), and parameters of the parasitic element are optimized to maximize antenna gain and suppress sidelobe. Simulated and measured results of the fabricated antenna show that it has wide bandwidth, high efficiency, high gain, and low sidelobe level.

• Korean Journal of Social Welfare
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• v.56 no.1
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• pp.155-179
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• 2004

This study is about the effectiveness and activation strategies of vacational training programme for the disabled guided by the Ministry of Labour and the Korea Employment Promotion Agency for the Disabled(KEPAD). This research employed quantitative approach. The quantitative research used the samples of 853 disabled people who had finished vocational training programme during recent 3 years. In this research the effectiveness is categorized into two ; product effectiveness and employment effectiveness. Product effectiveness is influenced by the kind of train-center, train-area, train-length. The KEPAD, non-IT job area and train-period over 6 month are more effective. Employment effectiveness is significantly influenced by demo-sociological factor rather than disability factor. Especially the kind of train-center is very important to be employed for the disabled. This implicates that choice of train-center by the disabled and effective management of it by the public sector is very important in developing employment. Effective management, stated above, includes reengineering programmes and functions accountable to the need form the trainee, bridging the gap among train-centers in terms of performance, differentiation of financial support according to the product to save the public fund, encouraging one special programme in one train-center.