• Toxicological Research
• /
• v.13 no.4
• /
• pp.393-400
• /
• 1997

The effects of superoxide dismutase(SOD) and catalase on the toxicity of paraquat(PQ) were studied using diethyldithiocarbamate(DDC), 3-amino-1,2,4-triazole(AT) which are inhibitors of Cu, Zn-SOD and catalase in rats. Sprague Dawley rats were divide into 6 groups: control, DDC, PQ, AT, DDC+PQ, and AT+PQ group. The PQ (50 mg/kg body weight(BW); about half dose of $LD_{50}$) was administered with orally, otherwise AT(1.0g/kg BW) and DDC(1.0g/kg BW) were administered by intrperitoneal(iP) injection. The survival rate of rats in PQ+AT group was significantly decreased compared with PQ group while the difference of survival rate between DDC group and DDC+PQ group was not significant. The SOD activity after administration of DDC was decreased in liver, lung and kidney, but catalase activity was not changed. The catalase activity in liver, lung and kidney of AT treated rats was decreased, while SOD activity was not changed in this group. The effects of DDC and AT to the PQ toxicity was also observed in primary cultured rat Skin fibroblasts. The viable cells that was measured with MTT method, was decreased in AT+PQ treated group compared to PQ treated group, but the difference of cell viability between DDC treat group and DDC+PQ treated group was not observed. This result, AT potentlate PQ toxicity while DDC were not affect, suggested that the decreased catalase activity lead to elevation of hydrogen peroxide levels and PQ toxicity may be correlate with the hydrogen peroxide rather than the superoxides.

• Korean Journal of Optics and Photonics
• /
• v.19 no.1
• /
• pp.48-53
• /
• 2008

We propose an optical configuration to compensate dispersion characteristics in the dark state of normally black twisted nematic (NB-TN) liquid crystal display (LCD). We employed a half-wave plate (HWP) and a +A plate to achieve the superior dark state. By using the parameter space diagram (PSD) method, we could obtain the optimum values of parameters and the high contrast-ratio over 500 : 1 could be obtained. Furthermore, excellent dispersion characteristics were also obtained in the bright state. We could confirm the performance of the proposed structure using both the numerical calculations and the experiments.

• Proceedings of the IEEK Conference
• /
• summer
• /
• pp.199-203
• /
• 2004

In this paper, we only describe the digital block of two-channel 18-bit analog-to-digital (A/D) converter employing sigma-delta method and xl28 decimation. The device contains two fourth comb filters with 1-bit input from sigma­delta modulator. each followed by a digital half band FIR(Finite Impulse Response) filters. The external analog sigma-delta modulators are sampled at 6.144MHz and the digital words are output at 48kHz. The fourth-order comb filter has designed 3 types of ways for optimal power consumption and signal-to-noise ratio. The following 3 digital filters are designed with 12tap, 22tap and 116tap to meet the specification. These filters eliminate images of the base band audio signal that exist at multiples of the input sample rate. We also designed these filters with 8bit and 16bit filter coefficient to analysis signal-to-noise ratio and hardware complexity. It also included digital output interface block for I2S serial data protocol, test circuit and internal input vector generator. It is fabricated with 0.35um HYNIX standard CMOS cell library with 3.3V supply voltage and the chip size is 2000um by 2000um. The function and the performance have been verified using Verilog XL logic simulator and Matlab tool.

• Journal of Electrochemical Science and Technology
• /
• v.2 no.4
• /
• pp.204-210
• /
• 2011

Thin film electrodes have been intensively studied for active materials and current collectors to enhance the electrochemical performance. Here, porous structures of nickel-based oxide films, consisting of nickel oxide and copper (II) oxide, which was derived from the copper substrate during the annealing process, were deposited on metallic copper foils. The half-cell tests revealed excellent capacity retention after $80^{th}$ charge/discharge cycles. Some films showed an excess of the theoretical capacity of nickel oxides, which mainly originate from partially oxidized copper substrates during annealing. These results exhibit that both a preparation method of an active materials and partially oxidized current collectors could be important roles to apply thin film electrodes.

• Journal of Electrochemical Science and Technology
• /
• v.1 no.2
• /
• pp.97-101
• /
• 2010

In order to apply hybrid capacitor, $Li_2Mn_3O_7$ was synthesized by combustion method using $LiNO_3$, $Li(CH_3COO){\cdot}2H_2O$ and $Mn(CH_3COO){\cdot}4H_2O$. Spinel pattern was identified the samples calcined over $400^{\circ}C$ in XRD. Intensity of $Mn_2O_3$ peak increased as the calcination temperature increased. To decide n/p ratio and to investigate electrochemical properties, charge-discharge tests of Li/$Li_2Mn_3O_7$ and Li/AC half-cell were carried out. Applying to AC/$Li_2Mn_3O_7$ hybrid capacitor, it had high discharge capacitance of 32.8 F/cc at 100 mA/g.

• Magazine of the Korea Concrete Institute
• /
• v.9 no.6
• /
• pp.175-183
• /
• 1997

경제성장에 따른 항만구조물의 건설 및 유지관리에 관한 관심이 급격히 고조되고 있다. 이러한 항만구조물은 해양환경에 노출되어 콘크리트에 매입된 철근의 부식을 야기시키는 요인에 접해있다. 한편, 콘크리트 내부의 염분침투는 매입철근의 부식을 가속화시켜 콘크리트 구조물의 내구성에 상당히 큰 피해를 입힐 수 있다. 본 연구의 목적은 여러 가지 방식제를 사용함과 동시에 물/시멘트을 달리한 실험변수를 이용한 시험체에 대한 부식평가 및 매입철근의 적절한 부식방지 기법의 개발에 있다. 해양환경 조건을 simulation한 해수 및 담수 순환장치를 이용한 실내 시험체의 철근 부시도 평가 및 항만현장에 직접 거치된 시험체 등 다양한 조건하의 2년간의 실험이 현재 진행 중에 있다. 40주에 걸쳐 간헐 침투되는 해수조건에서 60개의 콘크리트 시험체의 철근 부시도 평가결과를 기초하여 180여개의 콘크리트 시험체를 새로이 제작하여 Half-Cell Test를 통한 Instant-Off Potential, Current Method를 통한 Corrosion current, Chloride Content 및 시험 종료후 시험체를 파쇄하여 부식된 철근의 무게측정등을 통하여 거동 및 부식을 예측.평가하고 이를 통한 부식방지기법을 개발하고자 한다.

• Journal of Electrochemical Science and Technology
• /
• v.10 no.1
• /
• pp.89-97
• /
• 2019

As a promising candidate for anode materials in lithium ion battery (LIB), tungsten trioxide ($WO_3$) and tungsten disulfide ($WS_2$) nanocrystals were synthesized, and their electrochemical properties were comprehensibly studied using a half cell. One-dimensional $WO_3$ nanowires with uniform diameter of 10 nm were synthesized by hydrothermal method, and two-dimensional (2D) $WS_2$ nanosheets by unique gas phase sulfurization of $WO_3$ using $H_2S$. $WS_2$ nanosheets exhibits uniformly 10 nm thickness. The $WO_3$ nanowires and $WS_2$ nanosheets showed maximum capacities of 552 and $633mA\;h\;g^{-1}$, respectively, after 100 cycles. Especially, the capacity of $WS_2$ is significantly larger than the theoretical capacity ($433mA\;h\;g^{-1}$). We also examined the cycling performance using a larger size $WO_3$ and $WS_2$ nanocrystals, showing that the smaller size plays an important role in enhancing the capacity of LIBs. The larger capacity of $WS_2$ nanosheets than the theoretical value is ascribed to the lower charge transfer resistance of 2D nanostructures.

• Journal of the Korean institute of surface engineering
• /
• v.54 no.4
• /
• pp.164-170
• /
• 2021

Vanadium redox flow batteries (VRFB) have emerged as large-scale energy storage systems (ESS) due to their advantages such as low cross-contamination, long life, and flexible design. However, Hydrogen evolution reaction (HER) in the negative half-cell causes a harmful influence on the performance of the VRFB by consuming current. Moreover, HER hinders V²⁺/V³⁺ redox reaction between electrode and electrolyte by forming a bubble. To address the HER problem, carbon nanotube/graphite felt electrode (CNT/GF) with oxygen functional groups was synthesized through the hydrothermal method in the H₂SO₄ + HNO₃ (3:1) mixed acid solution. These oxygen functional groups on the CNT/GF succeed in suppressing the HER and improving charge transfer for V²⁺/V³⁺ redox reaction. As a result, the oxygen functional group applied electrode exhibited a low overpotential of 0.395 V for V²⁺/V³⁺ redox reaction. Hence, this work could offer a new strategy to design and synthesize effective electrodes for HER suppression and improving the energy density of VRFB.

• Journal of Chest Surgery
• /
• v.35 no.9
• /
• pp.659-663
• /
• 2002

The objective of this study was to assess the usefulness of bone scans in routine preoperative examinations of patients with newly diagnosed non-small cell lung carcinoma. Material and Method: We reviewed the medical records of 258 patients who were newly diagnosed with non-small cell lung cancer in our hospital between January 2000 and December 2000. More than half of the patients (132) were deemed to be inoperable due to their advanced stage based on the CT scans. The remaining 126 patients were considered potentially operable. For these patients, clinical evaluation including the presence of bone pain, serum alkaline phosphatase, and calcium levels was used as clinical predictors of bone metastasis. All patients received bone scans. Bone X-rays, MRI or bone biopsy were performed to confirm the presence of bone metastasis. The usefulness of the bone scan was evaluated by comparing its power of predicting bone metastasis to that of the clinical information. Result: In all patients, the positive and negative predictive values of bone scans for the bone metastasis were 44%, and 99%, respectively. Those of the clinical information were 38% , and 94%. However, in potentially operable patients, the negative predictive value of the clinical information was as high as 99%. Conclusion: If newly diagnosed non-small cell lung cancer patients are presented as potentially operable on the basis of CT scan with no clinical evidence of distant metastases, curative resection could be considered without performing routine bone scans because of the low probability of bone metastasis. However, if there are positive clinical findings, further evaluations, including bone scan should be followed as metastasis will be documented in more than 30% of patients.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.3
• /
• pp.507-513
• /
• 2017

Bacillus subtilis spores can be used for protein display to engineer protein properties. This method overcomes viability and protein-folding concerns associated with traditional protein display methods. Spores remain viable under extreme conditions and the genotype/phenotype connection remains intact. In addition, the natural sporulation process eliminates protein-folding concerns that are coupled to the target protein traveling through cell membranes. Furthermore, ATP-dependent chaperones are present to assist in protein folding. CotA was optimized as a whole-cell biocatalyst immobilized in an inert matrix of the spore. In general, proteins that are immobilized have advantages in biocatalysis. For example, the protein can be easily removed from the reaction and it is more stable. The aim is to improve the pH stability using spore display. The maximum activity of CotA is between pH 4 and 5 for the substrate ABTS (ABTS = diammonium 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate). However, the activity dramatically decreases at pH 4. The activity is not significantly altered at pH 5. A library of approximately 3,000 clones was screened. A E498G variant was identified to have a half-life of inactivation ($t_{1/2}$) at pH 4 that was 24.8 times greater compared with wt-CotA. In a previous investigation, a CotA library was screened for organic solvent resistance and a T480A mutant was found. Consequently, T480A/E498G-CotA was constructed and the $t_{1/2}$ was 62.1 times greater than wt-CotA. Finally, E498G-CotA and T480A/E498G-CotA yielded 3.7- and 5.3-fold more product than did wt-CotA after recycling the biocatalyst seven times over 42 h.