• Journal of the Korean Society for Nondestructive Testing
• /
• v.23 no.4
• /
• pp.315-321
• /
• 2003

The integrity of the turbine rotors can be assessed by measuring the material properties at service temperature. In order to evaluate the remanent life of turbine rotor steel nondestructively, a measurement system of reversible magnetic permeability using an alternating perturbing magnetic field was constructed. We present a new non-destructive method to evaluate the remanent life of 1Cr-1Mo-0.25V steel using the value of reversible magnetic permeability. This method is based on the existence of reversible magnetic permeability in the differential magnetization around the coercive field strength. We measured the first harmonics voltage induced in a coil using a lock-in amplifier tuned to an exciting frequency. The Results of reversible magnetic Permeability and Wickers hardness on the aged samples show that the peak interval of reversible magnetic permeability (PIRMP) and Vickers hardness decreases as aging time increases. A softening curve is obtained from the correlation between Vickers hardness and the PIRMP. This curve can be used as a non-destructive method to evaluate the remanent life of turbine rotor steel.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2012.11a
• /
• pp.68-68
• /
• 2012

유기 용매를 사용하여 상온에서 실리콘계 전해 도금층을 형성하였다. 도금층의 몰폴로지는 전류밀도 및 도금 시간에 크게 영향을 받았으며, 다공성 구조에서 치밀한 구조까지 다양하게 나타났다. 조성 및 구조가 잘 정의된 실리콘계 전해 도금 층을 리튬이차전지용 애노드 활물질로써 평가해 본 결과 도금층 내 실리콘은 리튬과 가역적으로 반응하였다.

• Journal of the Korean Magnetics Society
• /
• v.5 no.4
• /
• pp.251-260
• /
• 1995

It has been reported that Co-based amorphous ferromagnetic alloys annealed in a small magnetic field develop a reproducible, asymmetric hysteresis loop. If the direction of the field during annealing is regarded as +, the magnetization reversal from - to + is smooth and reversible, with its slope determined by the demagnetizing field of the sample. This phenomenon is called the asymmetric magnetization reversal (AMR). The shape of the hyster-esis loop depends sensitively on the condition during the anneal and the alloy composition. Here, we report on the effect of the annealing temperature and time on AMR in a zero magnetostrictive ferromagnetic amorphous alloy. The AMR effect develops in a very short time at a reasonably high temperature, but is stabilized by annealing for a prolonged time.

• Korean Journal of Optics and Photonics
• /
• v.15 no.2
• /
• pp.109-113
• /
• 2004

We have manufactured and characterized the fiber-to-Planar Waveguide Coupler for analysis of the photo-induced refractive index change of DM-BTE .(l,2-bis[2,5-dimethylthio-phen-3-yl]-hexafluorocyclopentene) When irradiated with ultraviolet light, the colorless diarylethene(DM-BTE)-crystal turned red while keeping the crystal shape. The red color was bleached by irradiation with visible light(λ＞450 nm). The resonant wavelength was shifted and recovered owing to the refractive index variation of the planar waveguide because of its photo-functional properties on exposure to UV and visible light. The wavelength responses of this switch by UV exposure were measured as 0.057 nm/sec with saturation time of 60 seconds. and when illuminated by visible light, resonance wavelength variations were measured as 0.028 nm/sec, with recovery time of 140 seconds.

• Journal of the Microelectronics and Packaging Society
• /
• v.6 no.2
• /
• pp.69-74
• /
• 1999

Graphite and carbonaceous materials intercalate and deintercalate Li-ion reversibly into their layered structures. These materials show an excellent capacity for using a negative electrode in Li-ion batteries, because the electrochemical potential of Li-ion intercalated carbon is almost identical with that of lithium metal. Carbon used in this study was obtained by the pyrolysis of petroleum pitch, and heat-treated at the several temperatures between $700^{\circ}C$ and $1300^{\circ}C$. XRD analysis revealed that crystallization of carbon increased with increasing the heat treatment temperature. Charge/discharge properties were studied by a constant-current step at the rate of 0.1C, and the interfacial reaction between the electrolyte and the surface of carbon electrode was studied by cyclic voltammetry. Cell capacities were investigated in terms of the heat treatment temperature and the cycle number. Reversible capacity increased with the heat treatment temperature up to $1000^{\circ}C$, thereafter decreased continuously. Also, charge capacity decreased with the cycle number, while the reversibility improved with it.

• The Korean Journal of Applied Statistics
• /
• v.19 no.2
• /
• pp.305-317
• /
• 2006

Outliers adversely affect model identification, parameter estimation, and forecast in time series data. In particular, when outliers consist of a patch of additive outliers, the current outlier detection procedures suffer from the masking and swamping effects which make them inefficient. In this paper, we propose new outlier detection procedure based on high breakdown estimators, called as the dual robust filtering. Empirical and simulation studies in the autoregressive model with orders p show that the proposed procedure is effective.

• Journal of the Korean Chemical Society
• /
• v.48 no.2
• /
• pp.151-155
• /
• 2004

The self-assembled mololayers(SAMs)were prepared with cysteine(cys) and subsequently coupled with dopamine(dopa) containing quinone functionality on the gold modified electrodes. The SAMs annealed in ethanol for 6 hours gave a better shaped cyclic voltammogram which had a 0.28 V of formal potential and same redox potential in 0.1M phosphate buffer(pH=7.10). The electrodes were employed to determine concentration of HADH with the result that calibration curve exhibited an excellent correlation(${\geq}$ 0.993) for the concentrations ranging up to 5.0${\times}10^{-4}$ M.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.244-244
• /
• 2011

핵융합장치 내부의 플라즈마 대면재료는 고온의 플라즈마와 직접 대면하므로 수 십 MW/$m^2$에 이르는 큰 열부하에 따른 재료의 물성변화, 즉 고온환경에 따른 재료의 팽윤, 크리프(creep) 변형 그리고 금속이 가역성이나 연성을 잃는 취화현상 등이 중요한 연구주제이다. 고열부하의 인가를 통한 핵융합대면재료의 물성실험은 현재 국내에서는 탄소히터, 열플라즈마 등을 이용하여 이루어지고 있으며 국외에서는 짧은 시간에 큰 열부하를 인가할 수 있는 고출력 전자빔장치가 주요한 열부하실험장치로 활용되고 있다. 본 연구에서는 기초적인 실험이 가능한 고열부하용 전자빔조사장치를 제작하여 대표적인 플라즈마 대면재료인 텅스텐에 60 keV, 30 mA의 전자빔을 조사한 후 고열부하에 따른 텅스텐의 물성변화를 측정하였다.

• Applied Chemistry for Engineering
• /
• v.9 no.5
• /
• pp.786-790
• /
• 1998

K-GIC of the new carbon electrode to improve performance of carbon negative electrode in lithium ion secondary battery was prepated and its electrical characteristics were studied. Form this study, intercalated K quantity was increased in order of $2>3>1mole/{\ell}$ of KCl solution. And, for KCl solution of 1mole, the mole ratio of carbon and potassium was 156~388 carbon/potassium. The proper condition of K-GIC preparation was KCl solution of $1mole/{\ell}$, reaction temperature of $700^{\circ}C$, reaction time of 1 hour. From this condition, the intercalation and deintercalation behavior of lithium was very excellent. Also the reversibility was excellent.

• Journal of Yeungnam Medical Science
• /
• v.16 no.2
• /
• pp.326-332
• /
• 1999

Background: In korea the agricultural community widely uses organophosphorous, and organophosphorous poisonings are increasing every year. We compared change in activity of acetylcholinesterase and pseudocholinesterase by organophosphorous and by the interaction of ethanol and organophosphorous. We also compared the effect of reversible anticholinesterase drugs, physostigmine and neostigmine The object of this study is to investigate the effects of several anticholinesterase drugs and on how ethanol influences the activity of cholinesterase. Materials and Methods: Fifteen male university students were randomly selected, and blood samples were taken from the antecubital vein. The acetylcholinesterase in the RBC and the pseudocholinesterase in the serum were extracted and separated. The enzyme activity change was measured by the electrometric method. After adding acetylcholine, the pH change was measured with a pH meter. Results and Conclusion: Our results indicated that reversible anticholinesterase drugs decreased the cholinesterase activity more efficiently than organophosphorous. The acetyl cholinesterase and pseudocholinosterase activity were decreased by ethanol. When ethanol was added, oxime a cholinesterase activator, increased acetylcholinesterase activity but does not increased pseudocholinesterase activity.