• Korean Journal of Materials Research
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• v.22 no.2
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• pp.61-65
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• 2012

A $Li_2O-2SiO_2$ ($LS_2$) glass was investigated as a lithium-ion conducting oxide glass, which is applicable to a fast ionic conductor even at low temperature due to its high mechanical strength and chemical stability. The $Li_2O-2SiO_2$ glass is likely to be broken into small pieces when quenched; thus, it is difficult to fabricate a specifically sized sample. The production of properly sized glass samples is necessary for device applications. In this study, we applied spark plasma sintering (SPS) to fabricate $LS_2$ glass samples which have a particular size as well as high transparency. The sintered samples, $15mm\phi{\times}2mmT$ in size, ($LS_2$-s) were produced by SPS between $480^{\circ}C$ and $500^{\circ}C$ at 45MPa for 3~5mim, after which the thermal and dielectric properties of the $LS_2$-s samples were compared with those of quenched glass ($LS_2$-q) samples. Thermal behavior, crystalline structure, and electrical conductivity of both samples were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and an impedance/gain-phase analyzer, respectively. The results showed that the $LS_2$-s had an amorphous structure, like the $LS_2$-q sample, and that both samples took on the lithium disilicate structure after the heat treatment at $800^{\circ}C$. We observed similar dielectric peaks in both of the samples between room temperature and $700^{\circ}C$. The DC activation energies of the $LS_2$-q and $LS_2$-s samples were $0.48{\pm}0.05eV$ and $0.66{\pm}0.04eV$, while the AC activation energies were $0.48{\pm}0.05eV$ and $0.68{\pm}0.04eV$, respectively.

• Korean Journal of Veterinary Service
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• v.33 no.4
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• pp.375-385
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• 2010

An investigation was conducted to evaluate the effects of supplementing Alisma canaliculatum, Viscum album and Cornus officinalis probiotics on the growth performance and immune response in growing pigs. This experiment was conducted using 120 pigs (crossing of Landrace${\times}$Yorkshire and castrated) which were assigned to 5 treatments in 3 replications with 8 pigs per replications. The dietary treatments were NC group (without antibiotics), PC group (basal+Oxytetracycline 50ppm), AC group (basal+A. canaliculatum 0.5%), VA group (basal+V. album 0.5%) and COP group (basal+C. officinalis probiotics 0.5%). The initial body weights of pigs were 35kg on average and the experiment lasted for 9 weeks. The experimental animals were kept in the pens following a completely randomized design. They were provided the diets adequate for grower stage as recommended by NRC (ME:3,265 kcal/kg and CP:16%). COP fed pigs showed lower weight gain up to 6 weeks of age compared to NC group and other groups without significant differences (P>0.05). The carcass weights of pigs fed VA and COP were significantly higher compared to NC group (P<0.05), Back fat thicknesses groups fed three different additives were higher than NC group and lower then PC group (P<0.05). Crude fat contents in loin meat were significantly lower in groups fed three different additives while moisture contents of those three groups were higher than other groups (P<0.05). The thiobarbituric acid reaction substance (TBARS) value measured at fresh and $2^{nd}$ weeks was lower in additives fed groups but no statistical differences were observed among the treatments (P>0.05). Significantly highest PUFA (16.42g/100g) and ${\omega}$-3 fatty acids (ALA, EPA and DHA) content of meat were observed in COP fed pigs compared to NC group (P>0.05), which might mean that three additives function to enhance serum IgG in pigs. In consequence, it can be suggested that AC, VA and COP may have a potential to replace antibiotics as growth promoter and immune enhancer in the diets for growing pigs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3587-3593
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• 2009

Nowadays, the PV systems have been focused on the interconnection between the power source and the grid. The PV inverter, either single-phase or three-phase, can be considered as the core of the whole system because of an important role in the grid-interconnecting operation. An important issue in the inverter control is the load current regulation. In the literature, the Proportional+Integral (PI) controller, normally used in the current-controlled Voltage Source Inverter (VSI), cannot be a satisfactory controller for an ac system because of the steady-sate error and the poor disturbance rejection, especially in high-frequency range. By comparison with the PI controller, the Proportional+Resonant (PR) controller can introduce an infinite gain at the fundamental ac frequency; hence can achieve the zero steady-state error without requiring the complex transformation and the dq-coupling technique. In this paper, a PR controller is designed and adopted for replacing the PI controller. Based on the theoretical analyses, the PR controller based control strategy is implemented in a 32-bit fixed-point TMS320F2812 DSP and evaluated in a 3kW experimental prototype Photovoltaic (PV) power conditioning system (PCS). Simulation and experimental results are shown to verify the performance of implemented control scheme in PV PCS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2968-2974
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• 2010

Nowadays, the PV systems have been focused on the grid connection between the power source and the grid. The PV inverter can be considered as the core of the whole system because of an important role in the grid-interfacing operation. An important issue in the inverter control is the load current regulation. In the literature, Proportional Integral (PI) controller, which is normally used in the current-controlled Voltage Source Inverter (VSI), cannot be a satisfactory controller for an AC system because of the steady-sate error and the poor disturbance rejection, especially in high-frequency range. Compared with conventional PI controller, Proportional Resonant (PR) controller can introduce an infinite gain at the fundamental frequency of the AC source; hence it can achieve the zero steady-state error without requiring the complex transformation and the de-coupling technique. Theoretical analyses of both PI and PR controller are presented and verified by simulation and experiment. Both controller are implemented in a 32-bit fixed-point TMS320F2812 DSP processor and evaluated on a 3kW experimental prototype PV Power Conditioning System (PCS). Simulation and experimental results are shown to verify the controller performances.

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.197-202
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• 2001

M $g_{1-x}$ Z $n_{x}$O thin films with various composition x of ZnO were fabricated by a RF magnetron sputtering method, which is expected to improve the electro-optical properties of the conventional MgO protective layer for AC-PDP. Test panels with the $Mg_{1-x}$Z $n_{x}$O protective layer have been fabricated in order to investigate the effects of ZnO doping on the electrical characteristics of devices such as the discharge voltages and the memory gain. Experimental results revealed that test panels with the $Mg_{1-x}$Z $n_{x}$O(x=0.5at%) protective layer show lower firing and sustain voltages than those seen in panels with MgO protective layer by 20V. resulting in an increasement of the memory coefficient. In addition, it was found that test panels with the $Mg_{1-x}$Z $n_{x}$O protective layer show higher discharge intensity, i. e., higher plasma density, compared with panels with MgO protective layer.ve layer.layer.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.3
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• pp.213-221
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• 2004

In recent years, since more and more diode rectifiers with smoothing dc capacitor are used in electronic equipments, household appliances and ac drives, harmonics generated by these loads have become a major issue. In addition, 3-phase 4-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. This systems show excessive currents in the neutral. These neutral currents are fundamentally third harmonic, and their presence is tied to wiring failure, elevating of neutral potentials, transformer overheating, etc. In response to the concerns, this paper proposes a series active power filter scheme based on direct compensating voltage extraction method and the advantage of this control algorithm is direct extraction of compensation voltage reference without multiplying gain. Therefore, the calculation of the compensation voltage reference will becom much simpler than other control algorithm. To verify the effectiveness of the proposed algorithm, a prototype active power filter is built and some experiments are carried out.

• Korean Journal of Materials Research
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• v.12 no.6
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• pp.470-475
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• 2002

The effects of the conditions of the collector formation on electrical characteristics of the packaged SiGe hetero-junction bipolar transistors (HBT) were investigated. While the DC characteristics of SiGe HBTs such as IV characteristic, forward current gain, Early voltage, and breakdown voltage were hardly changed after packaging, the AC characteristics such as $f_{\tau}\; and\; f_{max}$ were degraded severely. With the rise of the collector concentration, the break-down voltage decreased but the $f_{\tau}$ increased. Additionally, $\beta$ and $f_{\tau}$ values were kept high in the range of elevated collector current due to the increase of the critical current density for the onset of the Kirk effect. The devices As implanted before the collector deposition showed lower breakdown voltage and higher $f_{\tau}$ than the others, which seems to be originated from the As up-diffusion resulting in the thinner collector.

• Journal of the Korean Society of Costume
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• v.29
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• pp.143-158
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• 1996

It was the year of 1903 when avantgarde artists in Vienna gave a birth to the Wiener Werkstaette under the influence of Aesthetic Movement and Guild of Handicraft from England. This study is on the backgrounds of the birth of the Wiener Werkstaette its artis-tic motto and world-wide echo it provoked. This thesis goes back to the time when the decadent Wiener Secession shaped up refiewing the Reform Movement It also covers characteristics works of major members of the Wiener Werkstaette which were produced on the basis of the concept of Gesmtkunstwerk, The conclusion of this study is that : 1. Without losing its own specifc features various fields of formative arts were combinded together coherently and succeeded to realize the idealistic art that is the com-posite are 2. The Wiener Werkstaette was strongly opposed to the ready-made clothes which be-came popular as the society was Industrialized and commercialized. unlike those ready-to-wear clathes those members of the Wiener Werkstaette preferred to make each clothes with different mateirals and printed their own unique pattern designs. 3.As a results of close relationships between the Wiener Werkstaette and paul poiret 'Stu-dio Martine' was established in paris and new pattern deslhns were introduced by Raoul Dufy. 4. After the break-out of World War One cultural exchanges with other foreign countries were vuirtually cut off and the Wiener Werkstaette was disconnected from the influence of Parisl That was the motive for Wiener Werkstaette to start building up its unique artistic style with peculiar materials techniques and methods of productionl Those brisk and creative activities of the Wiener Werkstaette brought forth "the Golden perlod of 1920s" 5. Its historic design and ornamental pattern were assessed as a prelude to the Post-mod-ernism Since the late 1970s with the redis-covery of the culture of vienna in 1900s. the Art to wear which was created by the 'Wiener Werkstaette' but unfortunately tucked away by the Greate Depression and nationalism has been revaluated and studied. In Korea it was since 1985 when 'the art to wear' began to gain attention widely. It is urged that the theory of the 'Gesamtkunstwerk' should be also ac-cepted and shared earnestly.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.662-672
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• 2009

Obesity has increased dramatically increased in recent days. It has resulted in obesity-associated diseases and metabolic syndromes including hyperlipidemia, diabetes and cardiovascular diseases. Our study was investigated to determine the antiobese effects of mixed 2 medicinal herbs (AR+AC) in rats fed high-fat diet with an abundance of carbohydrates. Two groups of male Sprague-Dawley rats were fed different diets during 8 weeks: normal diet containing 5% corn oil (w/w), high-fat diet containing 10% (w/w) lard plus 5% (w/w) corn oil (HF). And High-fat diet group was treated with saline or 100 mg/kg ARAC or 300 mg/kg ARAC (PO). Antiobese effect was evaluated by measuring the changes of body weight, adipose tissues weight. Also we examined levels of leptin, adiponectin and lipid profiles in serum. Finally we compared morphological change in adipocytes and hepatocytes between HF and ARAC group. Mixed combination of 2 medicinal herbs, but not alone, caused significant decrease in body weight, organ weight (liver, epididymal fat, and BAT) compared with control HF group. The ARAC group had markedly lower serum levels of adiponectin when compared with HF group. Also the epididymal white adipocyte size of ARAC group were diminished comparing to the HF group. These results suggest that the possibility of ARAC combination, as an antiobese formula, by suppression of body weight gain and increased lipid profiles.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.6
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• pp.383-389
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• 2001

We report on the design, fabrication, and characterization of 0.35${\mu}{\textrm}{m}$-gate AIGaAs/InGaAs PHEMTs for millimeter-wane applications. The epi-wafer structures were designed using ATLAS for optimum DC and AC characteristics, 0.351m-gate AIGaAs/rnGaAs PHEMTs having different gate widths and number of fingers were fabricated using electron beam lithography Dependence of RF characteristics of PHEMT on gate finger with and number of gate fingers have been investigated. PHEMT haying two 0.35$\times$60${\mu}{\textrm}{m}$$^2$ gate fingers showed the knee voltage, pinch-off voltage, drain saturation current density, and maximum transconductance of 1.2V, -1.5V, 275㎃/mm, and 260.17㎳/mm, respectively. The PHEMT showed fT(equation omitted)(current gain cut-off frequency) of 45㎓ and fmax(maximum oscillation frequency) of 100㎓. S$_{21}$ and MAG of the PHEMT were 3.6dB and 11.15dB, respectively, at 35㎓