• 대한공업교육학회지
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• v.30 no.1
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• pp.46-55
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• 2005

The purpose of this study is to contemplate the relationship between a cognitive styles(field-independence/dependence, Fl/D)and a technological problem solving(TPS) among the industrial high school students. When it comes to perception, remembrance and consideration, we all have our own individual and steady patterns. We call them cognitive styles. FI/D is one kind of cognitive styles and it is about how dependently we perceive the field which each object has. Custer(1995) presented the technological problem among problem solving existed in various types as organizing it with four conceptional frames, which are invention, design, trouble shooting and procedures. We tested 56students belong to B industrial high school in A city, Korea. We used Group Embedded Figures Test(GEFT) to experiment the FI/D cognitive styles. We also did the TPS test by using an appliance which a researcher has developed. The appliance was made according to the technological problem and its validity was justified by an expert. We came up with a correlation coefficient between the FI/D cognitive styles and TPS to figure out what kind of relationship those two variable factors have and how much they are correlated each other. The correlation coefficient turned out ".59" which means they have significant and positive correlation.To find out the TPS difference between FI group and FD group, we compared each group's TPS score. As a result of the analysis, the FI group's TPS score is significantly higher than FD group's one.

• Korean Journal of Optics and Photonics
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• v.8 no.5
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• pp.377-381
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• 1997

Poling condition in 2 mol% MgO-doped $LiNbO_3$ crystals is investigated by varying the amplitude of poling electric field from 3V/cm to 7V/cm. It is found that 5V/cm is the best value for the formation of single domain by analysing the characteristics of the second harmonic generation(SHG) as the function of temperature. The temperature dependence of the phase-matching profile of SHG for the crystal applied by a spatially modulated electric field is observed to be very different from the simple sinc function. The distorted profile can be consistently fitted with the numerical simulations. This shows that the crystal homogeneity can be tested by the SHG temperature phase-matching profile. In addition, the thermo birefringence coefficient and electro birefringence coefficient of SHG were measured from the temperature dependence of phase-matching profile and shifts of phase-matching temperature by appling electric field along c-axis.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.113-121
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• 1998

In natural convection flows, the fluid velocities are highly dependent on the thermal field and property variations can have a strong effect on both the flow and thermal fields. To examine the effect of property variations, at first, numerical analyses covering wide range of the Prandtl number under the same Rayleigh numbers have been carried out. Next, we have modeled the viscosity and thermal conductivity as parabolic functions of temperature and a comprehensive set of numerical solutions have been obtained to understand the effect. The Prandtl number dependence of Nusselt number is fairly strong even though the effect is still weak compared to the Rayleigh number dependence. When thermophysical properties are dependent on temperature, the flow field showed a fairly weak variation except near boundaries, whereas the temperature field is strongly affected, especially by the temperature dependent thermal conductivity.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.234-234
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• 2010

The PR transitions in asymmetric dot-in-double-quantum-well (DdWELL) photodetector is identified by bias-dependent spectral behaviors. Discrete n-i-n infrared photodetectors were fabricated on a 30-period asymmetric InAs-QD/[InGaAs/GaAs]/AlGaAs DdWELL wafer that was prepared by MBE technique. A 2.0-monolayer (ML) InAs QD ensemble was embedded in upper combined well of InGaAs/GaAs and each stack is separated by a 50-nm AlGaAs barrier. Each pixel has circular aperture of 300 um in diameter, and the mesa cell ($410{\times}410\;{\mu}m^2$) was defined by shallow etching. PR measurements were performed in the spectral range of $3{\sim}13\;{\mu}m$ (~ 100-400 meV) by using a Fourier-transform infrared (FTIR) spectrometer and a low-noise preamplifier. The asymmetric photodetector exhibits unique transition behaviors that near-/far-infrared (NIR/FIR) photoresponse (PR) bands are blue/red shifted by the electric field, contrasted to mid-infrared (MIR) with no dependence. In addition, the MIR-FIR dual-band spectra change into single-band feature by the polarity. A four-level energy band model is proposed for the transition scheme, and the field dependence of FIR bands numerically calculated by a simplified DdWELL structure is in good agreement with that of the PR spectra. The wavelength shift by the field strength and the spectral change by the polarity are discussed on the basis of four-level transition.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.228-233
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• 2010

The microwave permeability was measured in order to analyze the thickness dependence of loss properties in CoFeHfO thin films with varying thickness of t = 57~1368 nm. A single resonance peak (P1) at 2.95 GHz was appeared in the samples with thickness less than 405 nm, while second resonance peak (P2) at 547MHz was additionally appeared in the samples with thickness greater than 405 nm. The P2 was originated by the angle distribution of the easy axis, which was confirmed from the measured results of the change of imaginary permeability with applied magnetic field in the sample of 1368 nm thickness and low field torque curves. If the second peaks can be reduced by minimizing the angle distribution of the easy axis, the CoFeHfO thin films with thickness greater than 400 nm can be used for the compact microwave devices operated at up to 2 GHz ranges.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.97-103
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• 2001

Polycrystalline thin films of La$_{2}$3/Sr$_{1}$3/MnO$_3$(LSMO) were prepared by water-based sol-gel processing on thermally oxidized Si(100) substrate. The thickness dependence of the low-field tunnel-type magnetoresistance properties at room temperature was studied. Tunnel-type magnetoresistance at low-field is found to be strongly dependent on film thickness. Maximum value of tunnel-type magnetoresistance of LSMO thin films was appeared at the film thickness of ~1500 $\AA$. This behavior can be explained in terms of dead layer between LSMO thin film and Si(100) substrate and thermal lattice strain effect in the LSMO thin films.

• Journal of Pharmacopuncture
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• v.21 no.4
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• pp.277-283
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• 2018

Objectives: Ethanol withdrawal following its chronic use is a serious outcome and challenging to treatment. The chronic use of ethanol induces a progressive neuroplasticity in different reigns of brain. In this study we evaluated the effects of aqueous extract of Crocus sativus L. (saffron) and its active compound, crocin, on the withdrawal behavior induced after repeated administration of ethanol, in two regimens of prophylactic (administration of drugs concomitant with the induction of dependence) and treatment (administration of drugs during the period of ethanol withdrawal) in mice which received ethanol. Methods: Ethanol dependence was induced by oral administration of 10% v/v ethanol (2 g/kg) for 7 days. The aqueous extracts of saffron (40, 80 and 160) and crocin (10, 20 and 40 mg/kg) were administered to mice in two regimens of prophylactic (along with ethanol) and treatment (during withdrawal period). Diazepam (1 mg/kg) was used as a positive control. Six hours after discontinuation of the ethanol, seizure was evaluated by the sub-convulsive dose of pentyleneltetrazole (PTZ) (30 mg/kg). The open field test and Rota rod test were used for evaluation of locomotor activity and motor incoordination, respectively. Results: Both extracts and crocin increased the number of crossed lined in the open field test. PTZ kindling seizure was inhibited in animals received extract (80 and 160 mg/kg) in both regimens. Motor incoordination was only improved following administration of crocin. Conclusion: The aqueous extract of saffron and crocin can be considered as safe agents and reliable alternative to diazepam in management of ethanol withdrawal syndrome.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.93-96
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• 1990

The characteristics of an inverted staggered-type hydrogenated amorphous silicon thin film transistor has been analyzed by employing numerical simulation. The field effect mobility and threshold voltage are characterized as a function of density of deep and tail states and lattice temperature. It has been found that the density of deep states plays an important role of determining the threshold voltage, while the field effect mobility are very sensitive to the slope of band tail states. Also, the numerically temperature dependence of field effect mobility and threshold voltage has been in good agreements with the experimental results.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.218-221
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• 1999

Magnetization measurements have been carried out on grain aligned Hg-1223 with the applied field parallel to the c-axis. The temperature dependence of the lower critical field H$_{cl}$(T) was determined by considering the effect of the surface barrier on the magnetization. H$_{cl}$(T) have been determined .from magnetic hysteresis loops within the framework of the modified Kim-Anderson critical-state model, where the surface barrier and the lower critical field are explicitly considered. At high temperature, H$_{cl}$(T) is identified as H$_p$(T). This results are agreed with the theory of Bean-Livinston surface barriers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.87-91
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• 2013

Carbon-nanotube field-effect transistors (CNFETs) have drawn wide attention as one of the potential substitutes for metal-oxide-semiconductor field-effect transistors (MOSFETs) in the sub-10-nm era. Output characteristics of coaxially gated CNFETs were simulated using FETToy simulator to reveal the dependence of drain current on the nanotube diameter and gate oxide thickness. Nanotube diameter and gate oxide thickness employed in the simulation were 1.5, 3, and 6 nm. Simulation results show that drain current becomes large as the diameter of nanotube increases or insulator thickness decreases, and nanotube diameter affects the drain current more than the insulator thickness. An equation relating drain saturation current with nanotube diameter and insulator thickness is also proposed.