• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.158-158
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• 2009

기계적 에너지를 전기적 에너지로 변환하는 에너지 변환소자인 압전 세라믹스는 액추에이터, 변압기, 초음파모터 및 각종 센서로 응용되고 있으며, 그 응용분야는 크게 증가하고 있다. 최근에는 이러한 압전 소자를 앞으로 도래하는 ubiquitous, 무선 모바일 시대의 휴대용 전자제품, robotics 등의 분야에 적용하기 위하여 소형화 및 경량화를 구현하고자 다양한 연구가 진행되고 있다. 본 연구에서는 압전 특성이 우수한 PNN-PMN-PZT 삼원계 세라믹을 이용하여 압전 트랜스포머를 제작하고 전기적 특성을 평가하였다. 압전트랜스포머는 전왜-압전효과를 이용한 소전력용 고전압발생소자로서 종래의 권선형 트랜스포머에 비교해서 소형, 경량이면서 승압비가 높고 구조가 간단하므로 직류 고전압전원에 응용되고 있다. 압전트랜스의 이론적인 고찰은 Rosen 이후로 많은 연구자들에 의해서 보고되었다. 그런데 압전세라믹트랜스는 공진 시 강력한 에너지변환을 하기 때문에 재료의 물리적 특성이 매우 중요함에도 불구하고, 이러한 물리적 특성에 관한 연구는 거의 없었다. 따라서 본 연구에서는 물리적 특성과 전기적 특성의 상호 연관성을 고찰하고자 하였다. 압전트랜스용 재료는 전기기계결합계수($k_p$)와 기계적품질계수(Qm)가 높아야 한다. 전기기계결합계수를 높이기 위해서는 상경계 조성의 Pb(Zr,Ti)$O_3$[PZT]계 세라믹스가 가장 우수하다. 본 연구에서는 기계적 품질계수를 향상시키기 위해서 $Pb(Nn_{1/3}Nb_{2/3})_{0.06+x}(Mn_{1/3}Nb_{2/3})_{0.065-x}(Zr_{0.48}Ti_{0.52})_{0.875}0_3$계의 조성을 설계하여 압전특성을 평가하고 미세구조를 분석하였다. 또한 압전트랜스를 제작하여 입출력의 승압비 및 주파수 특성 등도 평가하였다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.1
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• pp.14-20
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• 1978

To find out the influence of mineral nutritions and phosphorus concentration to ferrous absorption of rice and barley plants were studied in the culture solution which has various levels of ferrous and phosphorus with deficiency of mineral nuritiont. The ferrous absorption of rice and barley plants were greatly affected by phosphorus and potassium in the culture solution among mineral nutritions. The ferrous absorption was decreased with the increasing of phosphorus concentration. The rate of ferrous translocation was higher in barley plant than that of rice plant. And also, the symptoms of ferrous toxicity occurred easily in the barley plant. From these results, it was concluded that the ferrous was more influential upon the growth of barley than that of rice.

• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.944-951
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• 2004

The influences of inoculum size, pH, and medium composition on mycelial growth and exopolysaccharides (EPS) production were investigated in shake flasks and in a bioreactor. The optimum inoculum size for both mycelial growth and EPS production was identified to be 10% (v/v) in shake flask cultures. The optimal initial pH for mycelial growth and EPS production in shake flask cultures were found to be 5.0 and 7.0, respectively. However, the optimal pH was 5.0 for both mycelial growth and EPS production in bioreactor cultures where the pH was regulated. The optimal mass ratio of the two major carbon sources, glucose to dextrin, was 1:4. The optimal mass ratio of the two major nitrogen sources, yeast extract to soy tone peptone, was 2:1. When 500 mg $1^{-1}$ of $MnSO_4-5H_2O$ was added to the bioreactor culture, both mycelial growth and EPS production were enhanced by approximately 10%. Under the optimized conditions, a mycelial biomass of 9.85 g $1^{-1}$ and an EPS concentration of 4.92 g $1^{-1}$ were obtained in 4 days.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.744-752
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• 1992

Polymer bonded metalloporphyrins are synthesized by reaction between Fe(III) protoporphyrin or Mn(II) tetrakis(4-N-carboxyphenyl)porphyrin with polystyrene divinylbenzene copolymer. The spectroscopic properties of synthetic polymer bonded metalloporphyrins are investigated by using resonance Raman spectrometer. By synthetic polymer bonded metalloporphyrins as catalyst, which are model of cytochrome P-450 and peroxidases, epoxidation of olefins and oxidation of alkanes are achieved with H2O2 as oxidant. The catalytic efficiencies with polymer bonded metalloporphyrins are improved on that with corresponding nonpolymer bonded metalloporphyrins. Especially those can be reused because of stability against oxidant. Electron donating imidazole derivatives, which are attached in 5th position of central metal of metalloporphyrins, enhance the catalytic efficiencies.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.11
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• pp.1509-1517
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• 2004

A study was conducted to determine the safety of feeding processed broiler litter (BL) to beef cattle. The litter was processed by deepstacking, ensiling and composting. The health issues addressed relevant to the safety of feeding litter included pathogenic bacteria, mycotoxins, heavy metals, medicinal drugs and pesticide residues. Exp. 1 evaluated the feed hygiene of processed rice hulls-bedded BL. The presence of pathogenic bacteria in BL was determined before and after deepstacking. A total of 21 BL samples were collected over a 3-year period of commercial and experimental production of BL for beef cattle. Exp. 2 evaluated the safety of meat of cattle fed deepstacked BL. In Exp. 1, there were no pathogenic bacteria, such as coliform, E. coli, E. coli O157:H7, Salmonella, Listeria and Proteus, in deepstacked BL. Levels of heavy metals (Cu, Fe, Mn and Zn) and toxic heavy metals (As, Pb, Cd and Hg) were lower than the commercial feed tolerances. Aflatoxin, medicinal drug and pesticide residues were detected at extremely low levels. In Exp. 2, the meat of the BL-fed animals exhibited few differences in all analyzed items from that of the control group, showing safety from pathogenic microorganisms and heavy metals. When BL was withdrawn for 14 days prior to slaughtering the BLfed cattle, no medicinal drug residues were detected in the meat. Pesticides in the tissues of either group of animals were much lower than the tolerances. In conclusion, processed rice hulls-bedded BL and the meat of cattle fed BL were safe from the potential hazards of pathogenic bacteria, heavy metals, aflatoxin, medicinal drugs and pesticide residues.

• Journal of Electrochemical Science and Technology
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• v.1 no.1
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• pp.39-44
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• 2010

1.5 V and 3.0 V-class film-type primary batteries were designed for radio frequency identification (RFID) tag. Efficient fabrication processes such as screen-printings of conducting layer ($25{\mu}m$), active material layer ($40{\mu}m$ for anode and $80{\mu}m$ for cathode), and electrolyte/separator/electrolyte layer ($100{\mu}m$), were adopted to give better performances of the 1.5 V-class film-type Leclanch$\acute{e}$ primary battery for battery-assisted passive (BAP) RFID tag. Lithium (Li) metal is used as an anode material in a 3.0 V-class film-type $MnO_2||$Li primary battery to increase the operating voltage and discharge capacity for application to active sensor tags of a radio frequency identification system. The fabricated 3.0 V-class film-type Li primary battery passes several safety tests and achieves a discharge capacity of more than 9 mAh $cm^{-2}$.

• Journal of Microbiology
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• v.41 no.1
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• pp.28-33
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• 2003

Pycnogenol (PYC) is believed to have potential as a therapeutic agent against free radical-mediated oxidative stress. It is important, therefore, to understand the interactions between PYC and cellular defenses against oxidative stress. Toward this end, we analyzed the survival rates on the gene expression responses of E. coli sod katG mutants to PYC after pre-treatment of PQ or H$_2$O$_2$-mediated stress under aerobic conditions. We identified SOD induced by PYC, but not HP1 in sod hate mutants. A striking result was the PYC induction of SOD with antioxidant property in single katG mutant cells, particularly MnSOD and CuZnSOD. These inductions were further increased with oxidative stress, while HP1 was not induced in these conditions. The effects of pycnogenol treatment on these cells depend in part on its concentration on the stress response. Protective effects of PYC exposure which affected gene expression in cells were consistent with cell survival rates. Our results demonstrate that pycnogenol may alter the stress response gene expression in a specific manner such as SOXRS because PYC induction of single mutant only worked under increased PQ stress. All together our data indicate that SOD activity is essential for the cellular defense against PQ-mediated oxidative stress, suggesting that PYC may not be effective as an antioxidant in only oxidative stress conditions. On the other hand, it was expected that PYC may play a role as a pro-oxidant and if it is available for use, it should be evaluated carefully.

• Herbal Formula Science
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• v.29 no.1
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• pp.1-8
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• 2021

Objectives : The purpose of this study was to investigate the antioxidant activity of water extract of Ojayeonjonghwan (OYH) in GC-1 germ cell lines. Methods : DPPH radical scavenging activity and cell viability assays in GC-1 germ cell lines were performed. In addition, the protective effects of OYH against hydrogen peroxide-induced oxidative stress in GC-1 germ cell lines were examined by measuring cell viability after H2O2 treatmet. The formation of ROS and the antioxidant enzymes activity such as SOD and catalase were measured in the same condition. Results : OYH scavenged DPPH radical dose-dependent manner and the IC50 was 63.79 ㎍/ml. OYH showed no cytotoxicity at concentration of 1, 10, 100 ㎍/ml. The hydrogen peroxide-induced cytotoxicity of GC-1 germ cell lines was protected to 53.66% by OYH at concentration of 10 ㎍/ml. OYH effectively inhibited ROS production in GC-1 germ cell lines. Mn SOD and catalase protein expression were significantly increased in GC-1 germ cell lines, but Cu/Zn SOD protein expression was not significantly changed. Conclusions : In conclusion, OYH has antioxidant activities against hydrogen peroxide-induced oxidative stress in GC-1 germ cell lines.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.508-512
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• 1998

The NTC thermistors were sintered by using microwave hybrid heating method at $1100^{\circ}C$~$1300^{\circ}C$ and those electrical properties were investigated. The obtained $B_{25^{\circ}C/85^{\circ}C}$ values from temperature dependence of electrical resisitivity were around 3100~3200 K which were almost the same values as conventionally sintered ones. Compared with conventional sintering process, this process could complete whole sintering process within 20 minutes. This the processing time and energy consumption could be reduced through this rapid heating by using microwave hybrid heating.t there were showed only two peaks, glycolide melting peak and lower molecular weight melting peak without lauryl alcohol. Conversion increased slowly with the reaction time up to 50 minutes, and then gave a sudden increase above that. The reaction time to disappear in glycolide melting peak during polymerization was shortened with the increase of lauryl alcohol content. Zero-shear viscosity of polyglycolic acid decreased with the increase of free acid content in glycolide.ssional energy and bending hysteresis increased. \circled3 Surface characteristics such as friction coefficient and thickness variation of highly shrinkage fabrics became relatively roughened state. \circled4 Since stiffened and roughened characteristics of highly shrinkage fabrics, drapabilities of them were significantly lowered. Additionally thermal insulation property of high shrinkage fabric was higher than that of low shrinkage fabric due to bulky and thickened feature. From the results, it is considered that the silk fabrics with high filling shrinkage have the good bulkiness and heat keeping properties and thus they have the suitable characteristics for high quality men's and women's formal garments.

• Journal of Animal Science and Technology
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• v.52 no.4
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• pp.319-328
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• 2010

This work was carried out to investigate the quantity of excreta and its composition in crossbred pigs (Yorkshire ${\times}$ Landrace ${\times}$ Duroc) at different stages of growth. Twelve young piglets (average BW weight of $19.0{\pm}0.33kg$) were used in this study. Pigs were divided into four phases during growing time and two phases during finishing time. The average excreta production for growing pig was 3.46 kg/head/day (feces: 1.07 kg, urine: 2.39 kg). The average moisture contents of feces and urine were 70.54% and 97.39%, respectively. Contents of Calcium, Magnesium, Copper, Plumbum, and Arsenic were 1.00%, 0.26%, 10.47 mg/kg, 2.43 mg/kg, and 1.02 mg/kg, respectively. The concentration of the water pollutants like Biochemical Oxygen Demand ($BOD_5$), Chemical Oxygen Demand (COD), Suspended Solid (SS), Total Nitrogen (TN) and Total Phosphorus (TP), excreted from pig were 96335, 61073, 207466, 8104 and 4209 mg/L in feces and 7364, 7149, 2715, 10110 and 613 mg/L in urine at the end of test, respectively. The daily loading amount of water pollutants ($BOD_5$, COD, SS, TN, and TP, respectively) in pig excreta were 102.1, 61.8, 221.6, 8.7, and 3.9 g/head/day in feces, and 19.3, 16.7, 8.0, 22.2, and 1.3 g/head/day in urine, respectively. The Nitrogen, $P_2O_5$, and $K_2O$ contents in the excreta of pigs were 0.96, 0.83 and 0.42% in feces, and 0.80, 0.09 and 0.53% in urine, respectively. Finally, this work was suggested to give basic information to swine farms.