• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.486-487
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• 2000

• Journal of Magnetics
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• 제17권4호
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• pp.245-250
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• 2012

Ferromagnetic resonance and X-ray specular reflectivity measurements were performed on $Ni_{81}Fe_{19}/Ir_{20}Mn_{80}/Co_{90}Fe_{10}$ exchange bias trilayers, which were grown using the pulsed-DC magnetron sputtering technique on Si(100)/$SiO_2$(1000 nm) substrates, to investigate the evolution of the interface roughness and exchange bias and their dependence on the NiFe layer thickness. The interface roughness values of the samples decrease with increasing NiFe thickness. The in-plane ferromagnetic resonance measurements indicate that the exchange bias field and the peak-to-peak line widths of the resonance curves are inversely proportional to the NiFe thickness. Furthermore, both the exchange bias field and the interface roughness show almost the same dependence on the NiFe layer thickness. The out-of plane angular dependent measurements indicate that the exchange bias arises predominantly from a variation of exchange anisotropy due to changes in interfacial structure. The correlation between the exchange bias and the interface roughness is discussed.

• Journal of the Optical Society of Korea
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• 제12권2호
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• pp.112-117
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• 2008

Single-mode propagation conditions of X-ray waveguides are investigated by numerical calculations in order to understand the importance of waveguide design parameters, such as core thickness and the optical constants of waveguide materials, on the transmission and coherence properties of the waveguide. The simulation code for mode analyzing is developed based on a numerical solution of the parabolic wave equation. The initial boundary value problem is solved numerically using a finite-difference scheme based on the Crank-Nicolson scheme. The E-field intensities in a core layer are calculated at an X-ray energy of 8.0 keV for air and beryllium(Be) core waveguides with different cladding layers such as Pt, Au, W, Ni and Si to determine the dependence on waveguide materials. The highest E-field intensity radiated at the exit of the waveguide is obtained from the Pt cladded beryllium core with a thickness of 20 nm. However, the intensity from the air core waveguide with Pt cladding reaches 64% of the Be-Pt waveguide. The dependence on the core thickness, which is the major parameter used to generate a single mode in the waveguide, is investigated for the air-Pt, and Be-Pt waveguides at an X-ray energy of 8.0 keV. The mode profiles at the exit are shown for the single mode at a thickness of up to 20 nm for the air-Pt and the Be-Pt waveguides.

• 생물정신의학
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• 제24권2호
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• pp.68-74
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• 2017

Objectives It is well known that problem drinking is associated with alterations of brain structures and functions. Brain functions related to alcohol consumption can be determined by the resting state functional connectivity in various resting state networks (RSNs). This study aims to ascertain the alcohol effect on the structures forming predetermined RSNs by assessing their cortical thickness. Methods Twenty-six abstinent male patients with alcohol dependence and the same number of age-matched healthy control were recruited from an inpatient mental hospital and community. All participants underwent a 3T MRI scan. Averaged cortical thickness of areas constituting 7 RSNs were determined by using FreeSurfer with Yeo atlas derived from cortical parcellation estimated by intrinsic functional connectivity. Results There were significant group differences of mean cortical thicknesses (Cohen's d, corrected p) in ventral attention (1.01, < 0.01), dorsal attention (0.93, 0.01), somatomotor (0.90, 0.01), and visual (0.88, 0.02) networks. We could not find significant group differences in the default mode network. There were also significant group differences of gray matter volumes corrected by head size across the all networks. However, there were no group differences of surface area in each network. Conclusions There are differences in degree and pattern of structural recovery after abstinence across areas forming RSNs. Considering the previous observation that group differences of functional connectivity were significant only in networks related to task-positive networks such as dorsal attention and cognitive control networks, we can explain recovery pattern of cognition and emotion related to the default mode network and the mechanisms for craving and relapse associated with task-positive networks.

• 한국산학기술학회논문지
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• 제10권7호
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• pp.1489-1496
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• 2009

비정질 인듐-갈륨-아연 산화물 박막트랜지스터를 모델링 하여서, 능동층의 구조, 두께, 평형상태의 전자밀도에 대응하는 박막트랜지스터의 특성을 연구하였다. 단일 능동층 박막트랜지스터의 경우, 능동층이 얇을 때 높은 전계효과이동도를 보였다. 문턱전압의 절대값은 능동층의 두께가 20 nm일 때 최저치를 보였으며, 문턱전압이하 기울기는 두께에 대한 의존성을 보이지 않았다. 복층구조 능동층의 경우, 하부의 능동층이 높은 평형상태 전자밀도를 가질 때보다 우수한 스위칭 특성을 보였다. 이 경우에도 능동층의 두께가 얇을 때에 높은 전계효과 이동도를 보였다. 높은 평형상태 전자밀도의 능동층의 두께를 증가시키면 문턱전압은 음의 방향으로 이동하였다. 문턱전압이하 기울기는 능동층의 구조에 대하여 특별한 의존성을 보이지 않았다. 이상과 같은 데이터는 산화물반도체 박막트랜지스터 능동층의 구조, 두께, 도핑비율을 최적화함에 효과적으로 사용될 것으로 기대된다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.1015-1018
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• 2006

The use of passive microwave data for estimating sea-ice thickness is limited by strong dependence of emissivity on near-surface brine. However, this particular characteristic becomes a basis for an algorithm to estimate thickness of thin sea-ice if a thickness-salinity-emissivity relationship is established. This study aims at developing an algorithm to estimate sea ice thickness on the basis of this relationship. In order to establish a thickness-salinity-emissivity relationship, we have conducted multi-platform synchronous observations in the Sea of Okhotsk. We note a positive relationship between thickness and brightness temperature. From observations, we also establish an empirical relationship between salinity and emissivity, thus between thickness and brightness temperature. The derived relationship is qualitatively similar to the one based on Hoekstra and Cappillino's formulation. Our results suggest that for thin sea-ice in the winter period there is potential to develop an algorithm to estimate sea-ice thickness.

• Tribology and Lubricants
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• 제18권4호
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• pp.255-259
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• 2002

The tribological properties of eight different liquid crystals were investigated in a concentrated point contact device and a ball-on-flat contact. For comparison, the same tests were also performed with commercial greases and the corresponding base oils. Under the fully flooded conditions studied, liquid crystals in a concentrated point contact showed lower friction than commercial greases and greater film thickness dependence on rolling speed than grease base oils or greases. Test results also showed that the film thickness and friction were little influenced by the composition of the examined liquid crystals.

• Journal of Information Display
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• 제13권1호
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• pp.31-36
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• 2012

Ferroelectric liquid crystal parameters, spontaneous polarization, and transition temperature were studied as a function of cell thickness. These parameters were found to increase with increasing cell thickness, but an exception was observed for the transition temperature in the case of a thin cell. A simple Landau model is presented to interpret the theoretical and experimental observations. The anomalous behavior is attributed to the electroclinic effect and is explained using the Landau model.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.703-706
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• 2009

The external electrode fluorescent lamp(EEFL) has recently been applied to backlight of LCD TV as a new light source. The dependence of the electro-optic characteristics of the EEFL used in direct-lit backlights on the glass thickness was examined in detail, and the ultraviolet(UV)-light efficiency was estimated. It was found that the lamp efficiency became larger as the glass thickness decreased if other conditions were the same.

• 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.