• 대한공업교육학회지
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• 제30권1호
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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.

• 한국광학회지
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• 제8권5호
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• pp.377-381
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• 1997

MgO가 2 mole% 첨가된 LiNbO$_{3}$ 결정을 3 V/cm, 5 V/cm, 7 V/cm의 전기장에서 poling하여, 5 V/cm의 전기장이 최적의 조건임을 제2고조파발생의 온도의존도특성을 관찰하여 알 수 있었다. 결정에 공간적으로 변조된 전기장을 인가하여 온도 위상 정합 모양이 찌그러짐을 관찰하였으며, 이 결과와 잘 일치하는 계산값을 정량적으로 구할 수 있었다. 이것으로부터 제2고조파의 온도위상정합모양을 이용하여 결정의 균일성을 판단할 수 있음을 증명하였다. 5 V/cm로 poling된 단결정의 온도 위상 정합 모양으로부터 온도에 따른 복굴절의 변화율, c-축으로 전기장을 인가하여 변화된 위상 정합 온도로부터 전기장에 따른 복굴절의 변화율을 계산하였다.

• 에너지공학
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• 제7권1호
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• pp.113-121
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• 1998

자연대류열전달에 있어서 유체의 속도는 온도장에 의해 크게 영향을 받는다. 따라서 유체의 물성치의 변화는 유동장 및 온도장에 크게 영향을 미칠 수 있다. 본 연구에서는 물성치에 의한 영향을 분석하기 위하여 동일한 레이레이수(Rayleigh number)하에서 물성치의 대표적인 무차원수인 프란틀수(Prandtl number)가 넓은 범위에서 변하는 경우에 대한 연구를 수행하였다. 그리고 유체의 점성계수 및 열전도도를 온도에 따른 2차원 다항식 함수로 모델링하여 전산해석을 시도하여 그 영향을 분석하고자 시도하였다. 열전달량의 척도인 누셀트수(Nusselt number)의 프란틀수 의존도는 레이레이수 의존도에 비하면 약한 편이지만 비교적 강한 것으로 나타났다. 물성치가 온도의 함수로 주어지는 경우, 유동장은 경계면을 제외하고는 비교적 강한 것으로 나타났다. 물성치가 온도의 함수로 주어지는 경우, 유동장은 경계면을 제외하고는 비교적 약한 영향을 받지만 온도장은 강한 영향을 받는 것으로 나타났으며, 특히 열전도도가 온도의 함수로 주어지는 경우에 온도장에 미치는 영향은 상당히 강한 것으로 관찰되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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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.

• 한국자기학회지
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• 제20권6호
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• pp.228-233
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• 2010

본 연구에서는 비정질 CoFeHfO 박막 재료의 두께 변화에 따른 고주파 손실 특성을 분석하기 위하여 57~1368 nm 두께의 CoFeHfO 박막 재료에 대해 마이크로파 투자율 특성을 분석하였다. 두께가 405 nm이하에서 허수부 투자율은 2.95 GHz에서 하나의 공진주파수를 보이지만, 405 nm 이상에서는 2.97 GHz와 547 MHz에서 두 개의 공진주파수를 보인다. 저자장하에서 측정한 토오크 곡선 결과로부터 547 MHz에서 발생되는 공진주파수는 CoFeHfO 재료의 자화 용이축들의 각도 분포에 기인하는 것으로 자기장의 세기에 따라서 급격하게 감소하는 특성을 보인다. 따라서 두께가 400 nm 이상의 CoFeHfO 박막 재료를 2 GHz 대역에서 작동하는 초소형 마이크로파 부품에 적용하기 위해서는 자화 용이축의 분포각도를 최소화시켜야 한다.

• 한국자기학회지
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• 제11권3호
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• pp.97-103
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• 2001

Water-based 졸겔 증착법을 이용하여 디결정체 La$_{2}$3/Sr$_{1}$3/MnO$_3$(LSMO) 박막을 2000$\AA$ 두께의 열 산화층을 갖는 Si(100) 기판상에 제조하여 상온에서 LSMO박막의 두께변화 따른 저 자장영역(120 Oe)에서의 터널형 자기저항 변화를 연구하였다. XRD 회절분석 결과 단일상의 페롭스카이트 결정구조임을 알 수 있었으며 RBS 스펙트럼 분석결과 박막의 조성비 La:Sr:Mn:O는 0.67:0.33:1.0:3.0임을 알 수 있었다. LSMO 박막의 자성특성 측정결과 두께 증가에 따라 포화자화는 750$\AA$까지 급격한 증가현상을 보이다 150$\AA$을 기점으로 점차 감소하는 경향을 나타내고 있으며, 보자력은 800 $\AA$ 까지 급격한 증가를 보이다 일정해지는 경향을 볼 수 있었다. 저 자장영역에서의 터널형 자기저항 변화비는 약 1500 $\AA$의 두께 영역에서 최대값을 나타냄을 알 수 있었다. 이러한 저 자장 영역에서 LSMO 박막의 터널형 자기저항 변화비의 두께 의존성은 LSMO 박막과 Si 기판의 계면에 존재하는 상호확산 현상에 의한 dead layer의 존재 및 LSMO 박막의 열처리시 발생되는 열 격자 변형 효과로 설명하였다.

• 대한약침학회지
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• 제21권4호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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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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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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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.

• 한국전기전자재료학회논문지
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• 제26권2호
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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.