• 전자공학회논문지D
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• 제34D권12호
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• pp.89-100
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• 1997

This paper investigated a new type of low voltage threshold switch (LVTS). As distinguished from the many other types of electronic threshold switches, the LvTS is ; voltage controlled, occurs at low voltages ($V_{2}$ $O_{5}$lV devices. The average low threshold voltage < $V_{LVT}$>=218 mV (standard deviation =24mV~kT/q, where T=300K), and was independent of the device area (x100) and amorphous oxide occurred in an ~22.angs. thick interphase of the V/amorphous- $V_{2}$ $O_{5}$ contacts. At $V_{LVT}$ there was a transition from an initially low conductance (OFF) state into a succession of quantized states of higher conductance (ON). The OFF state was spatically homogeneous and dominated by tunneling into the interphase. The ON state conductances were consistent with the quantized conductances of ballistic transport through a one dimensional, quantum point contact. The temeprature dependence of $V_{LVT}$, and fit of the material parameters (dielectric function, barrier energy, conductivity) to the data, showed that transport in the OFF and ON states occurred in an interphase with the characteristics of, respectively, semiconducting and metallic V $O_{2}$. The experimental results suggest that the LVTS is likely to be observed in interphases produced by a critical event associated with an inelastic transfer of energy.rgy.y.rgy.

• Asian Pacific Journal of Cancer Prevention
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• 제14권5호
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• pp.3299-3304
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• 2013

Background: The Global Adult Tobacco Survey has 15 key indicators, cigarettes smoked per day (CPD) among daily smokers being one of them. The first wave of GATS in 14 countries indicated that mean CPD use is higher in women than men in India only, which is contrary to the current understanding of tobacco use globally. This study was undertaken to understand the unusual findings for mean CPD use in the GATS-India survey. Materials and Methods: Items B06a and B06b of the GATS India survey questionnaire that collected information on daily consumption of manufactured and rolled cigarettes were analyzed using SPSS software. Exclusive users were identified from these items after excluding the concurrent users of other tobacco products. Cigarette type, exclusive use and gender stratified analyses were made. Consumption of different types of cigarettes among the mixed users of manufactured and rolled cigarettes were correlated. Results: Higher mean number of CPD use among male daily-smokers was observed than their female counterparts in product specific analysis. Mean CPD as per GATS cigarette definition was higher in males than females for exclusive users but a reverse trend was observed in case of non-exclusive users. Use of manufactured cigarettes increased with increase in use of rolled cigarette among the mixed users and around half of these users reported equal CPD frequency for the both types of cigarettes. Conclusions: The anomaly in mean CPD estimate in GATS-India data was due to inclusion of two heterogeneous products to define cigarettes, variation in cigarette product specific user proportions contributing to the average and non-exclusive concurrent use of other tobacco products. The consumption pattern of cigarettes among the mixed users highlights bias in CPD reporting. Definition, analysis and interpretation of 'cigarettes per day' in the GATS India survey need to be improved by redefining cigarettes and making product specific analyses.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.85-91
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• 2010

본 논문에서는 원형편파 변환에 적합한 정사각형 마이크로스트립 안테나를 제안하였다. 제안한 안테나는 접지면의 비대칭 U자형 슬롯의 구조적 특징으로 인하여, 90도의 위상 차이를 갖는 직교전계가 형성되어 원형편파 특성을 형성한다. 또한 비대칭 U자형 슬롯의 대칭축에 따라 원형편파의 방향을 쉽게 조절할 수 있는 장점을 가지고 있다. 비대칭 U자형 슬롯의 대칭축은 두 개의 스위칭 다이오드를 이용하여, 전압조건의 상태에 따라 좌회전편파와 우회전 편파를 각각 실험적으로 구현하였다. 측정된 원형편파의 축비는 2.46 GHz 동작주파수에서 편파방향에 상관없이 약 1.5 dB의 높은 축비특성을 보여주며, 29 MHz (약 1.2 %) 축비 대역폭을 가짐을 실험적으로 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.392-392
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• 2011

Carbon nanotubes (CNT) emitter has widely become an attractive mechanism that draws growing interests for cold cathode field emission.$^{1,2}$ CNT yarns have demonstrated its potential as excellent field emitters.$^3$ Extensive simulations were carried out in designing a CNT yarn-based cathode assembly. The focal spot size dependence on the anode surface of the geometric parameters such as axial distance of the electrostatic focus lens from the cathode and the applied bias voltages at the cathode, grid mesh and electrostatic focus lens were studied. The detailed computer simulations using Opera 3D electromagnetic software$^4$ had revealed that a remarkable size of focal spot under a focusing lens triode type set-up design was achieved. The result of this optimization simulation would then be applied for the construction of the CNT yarn based micro-focus x-ray tube with its field emission characteristics evaluated.

• 한국자기학회지
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• 제16권3호
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• pp.186-191
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• 2006

자기터널접합 기반의 MRAM(magnetic random access memory)은 자기저항효과를 응용하는 메모리소자로서 비휘발성과 고속 정보처리가 가능할 뿐만 아니라 고집적화 할 수 있는 차세대 통합형 비휘발성 메모리이다. 그러나 기존의 메모리 소자들에 비해 스위칭 산포가 크고, 기록마진(writing margin)이 확보되지 않아 아직까지는 고집적화가 어려운 실정이다. 최근 포화자화가 낮은 NiFeSiB 및 CoFeSiB과 같은 비정질 강자성체를 자기터널접합의 자유층 재료로 사용하여 스위칭 자기장의 거대화를 크게 감소시켜 MRAM의 기록마진을 높이는 연구결과에 관해 정리하여 보았다. 그리고 이러한 물질을 이용하여 자기터널접합의 재생마진(reading margin)과 관련된 터널자기저항비의 인가전압의존성을 저감시킬 수 있었다. 본고에서는 나노자기소자 기술의 중요한 분야인 MRAM의 기술발전 방향과 연구사례를 소개하고자 한다.

• 대한전자공학회논문지SD
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• 제37권12호
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• pp.1-9
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• 2000

미세구조 N-채널 MOSFET의 게이트-소스 전압에 의존하는 유효 채널 캐리어 이동도와 소스 및 드레인 기생저항의 정확한 분리 추출을 위해서 새로운 ERM-방법을 제안하였다. ERM-방법은 선형영역에서 동작하는 게이트 길이가 다른 두개의 소자($W_m/L_m=30{\mu}m/0.6{\mu}m, 30{\mu}m/1{mu}m$)에 적용되었고 유효 채널 캐리어 이동도를 모델링하고 추출하는 과정에서 게이트-소스 전압에 의존하는 소스 및 드레인 기생저항의 영향을 고려하였다. ERM-방법으로 추출된 특성변수들을 사용한 해석적 모델식과 소자의 측정데이터를 비교해본 결과 오차가 거의 없이 일치하는 것을 확인하였다. 따라서, ERM-방법을 사용하면 대칭구조 및 비대칭구조 소자의 유효 채널 캐리어 이동도, 소스 및 드레인 기생저항과 다른 특성변수들을 정확하고 효율적으로 추출할 수 있을 것으로 기대된다.

• 한국재료학회지
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• 제10권11호
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• pp.732-737
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• 2000

$TEMAT/H_2$플라즈마를 이용하여 $TiO_{2\pm}{\delta}$를 증착하였다. Power를 300W에서 500W로 증가시켜 고 밀도 플라즈마를 형성시킨 경우에는 Ti 함유량이 크게 증가하였고, 무시할 정도의 C, N이 함유되었다. 기판에 bias를 가한 경우에도 Ti 양이 증가되면서, 증착률이 크게 증가되었다. 또한 매우 적은 양의 $H_2O(~10^{-4}Torr)$는 TEAMT[tetrakis (ethylmethylamido) titanium] 분해를 효율적으로 이루어 주어 C, N의 양을 크게 감소시키면서 $TiO_2$에 요구되는 충분한 O을 제공하였다. 결과적으로 플라즈마 반응에 의하여 생성된 Ti 양이온이 TiOx 박막형성에 주요한 기여를 하고 있으며, 고 밀도 플라즈마의 사용은 Ti 양이온 생성을 크게 증가시켜 주고, 분위기 중에 존재하는 미량의 수분이 TEMAT 분해 효율성을 크게 하여 $TiO_2$박막증착을 이루고 있다.

• KIEE International Transactions on Electrophysics and Applications
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• 제11C권3호
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• pp.70-74
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• 2001

Admittance or impedance spectroscopy is one of the powerful tools to study dielectric relaxation and loss processes in organic and inorganic materials. In this study, the frequency dependent properties of an indium tin oxide/tris(8-hydroxyquinoline) aluminum($Alq_3$)/aluminum structure have been studied. The conductance of the $Alq_3$ film increases with the DC applied voltage up to 4V and decreases above 4V in the low frequency region. This indicates that the resistance of the device decreases with the applied bias due to the carrier injection enhancement, thereafter the injected carriers form the space charge and the additional injection of carriers is prevented. The Cole-Cole plot of the admittance takes a one-semicircle shape, which means that the device can be modeled as a parallel resistor-capacitor network. The resistance and capacitance were estimated as 8.62k${\Omega}$ and 2.7nF, respectively, at 3V in the low frequency region. The dielectric constant ( ${\epsilon}'$ ) of the $Alq_3$ film is independent of the frequency in the low frequency region below 100kHz, while the frequency dependency was observed at above 100kHz. The dielectric loss factor ( ${\epsilon}"$ ) of the $Alq_3$ film shows the dielectric dispersion below 100kHz and dielectric absorption in higher frequency domain. The dispersion is thought to be related to the hopping process of the carriers. The ${\epsilon}"$ is proportional to the reciprocal of the frequency. The dielectric relaxation time was extracted to about 0.318${\mu}s$ from the dielectric absorption spectrum.

• 한국식품영양과학회지
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• 제42권5호
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• pp.832-836
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• 2013

어묵의 유통기한을 예측하기 위해서 어묵을 30, 35, $40^{\circ}C$에서 각각 저장하면서 저장기간 중 총 호기성균 수를 측정하였다. Gompertz model을 이용하여 최대성장속도와 유도기를 구하였고, 각 parameter의 온도 의존성에 대한 식을 통해 유통기한에 관한 예측모델 식을 얻었다. 예측모델 식으로부터 계산된 유통기한은 0, 4, $10^{\circ}C$에서 각각 6.9, 5.5, 3.8일이었다. 이렇게 얻어진 예측모델 식의 적합성 평가를 위해 $A_f$와 $B_f$ 값을 산출한 결과, 각각 1.008, 1.003으로 나타나 예측모델식의 적합성이 뛰어났다. 이러한 결과로부터 본 연구에서 얻어진 유통기한예측 모델 식은 어묵의 유통기한 설정의 기초연구로써 활용될 수 있다고 판단된다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.535-540
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• 2006

The relationship between the observable noise model and the satellite elevation angle can be modeled quite well by an exponential function.[Jin, 1996] Noise size and dependence on the elevation angle are, however, different for each observation and receiver type. Therefore, the coefficient determination of this model is an issue, and various methods including PR-CP, single difference, and time difference have been suggested. The limitations of them are difficulty to model the carrier phase noise and to eliminate bias. To overcome these disadvantages for using Jin's model, we suggest zero baseline double difference (DD) and noise sorting algorithm. Data DD technique in zero baseline is useful to eliminate all the troublesome GPS biases, and the remaining error is the sum of GPS measurement noises from two satellites. These DD residuals for hours should be sorted by the combination of satellite elevation angles, and then variance value of the residual for each combination can be estimated. Using these values, we construct an over-determined linear equation whose solution is a set of noise variance for each satellite elevation angle. With 24hr Trimble 4000ssi data, we easily worked out the coefficients of the noise model not only for pseudorange but also for carrier phase. We estimated the standard deviation of the measurement DD using our model, and plotted 1 and 3 sigma lines for every epoch to verify the representation of the residual error. 63.3% of pseudorange residual and 65.9% of phase error did not exceed the 1 sigma lines. Additionally, 99.2% and 99.5% of them lied within 3sigma line. These figures prove that the Gaussian property of measurement noise, and that the suggested model by our algorithm corresponds to the observable noise information.