• E2M - 전기 전자와 첨단 소재
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• 제10권2호
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• pp.105-112
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• 1997

Undoped and Co$^{2+}$-doped Zn$_{4}$GeSe$_{6}$ single crystals were grown by the Chemical Transport Reaction method using iodine as a transporting agent. The crystal structure of these compounds determined by X-ray diffraction analysis was monoclinic structure. The direct energy gaps of these compounds were measured and the temperature dependence of the optical energy gap were closely investigated over the temperature range 10-290K. The temperature dependence of the optical energy gap is well presented by the Varshni equation. Also the optical absorption peaks of Zn$_{4}$GeSe$_{6}$ :Co$^{2+}$ single crystal observed, centered at 5437, 6079, 7142, 12950, 13462, 14786 and 15735 $cm^{-1}$ /, can be explained in terms of the electronic transitions of Co$^{2+}$ ions located at Td symmetry of the host materials. According to the crystal-field theory, the crystal-field, Racah and spin-orbit coupling parameters obtained from the absorption bands are given by Dq = 361$cm^{-1}$ /, B = 655$cm^{-1}$ / and .lambda. = 284$cm^{-1}$ / respectively.ively.

• 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.

• 한국광학회:학술대회논문집
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• 한국광학회 1999년도 제16회 광학 및 양자전자 학술발표회Proceedings of 16th Optics and Quantum Electronics Conference, 1999
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• pp.222-223
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• 1999

The structural dependence of harmonic and intermodulation distortion characteristics in 1.55${\mu}{\textrm}{m}$ DFB-LCD were investigated. The linearity of 1.55${\mu}{\textrm}{m}$ DFB-LD was greatly improved by employing a partially corrugated structure.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1994년도 춘계공동학술대회논문집; 창원대학교; 08월 09일 Apr. 1994
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• pp.742-748
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• 1994

Scientific involvement in complex decision-making systems, characterized by multicriteria phenomena and fuzziness inherent in the structure of information, requires suitable methods. Especially, when powerful dependent criteria are introduced, the systems are become more complex. This paper presents a fuzzy dependence relation model for this kind of multicriteria decision-making. The model we propose is based on fuzzy relation in fuzzy system theory. For the application of the model a numerical example is quoted.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.501-504
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• 2014

Si nanowire는 트랜지스터, 배터리 등 광범위한 응용이 가능한 물질로서 이의 효율적 활용을 위해서는 그 다양한 구조에 대한 물성 변화의 연구가 중요하다. 이 연구에서는 [110] 방향의 $4{\times}3$, $6{\times}4$, $8{\times}5$ Si nanowire에 대하여 DFT 기반 제일원리적 계산을 수행함으로써, $6{\sim}14{\AA}$ 범위에서 nanowire 지름의 변화에 따른 전자구조 의존성에 대하여 연구하였다. 그 결과, bulk와 비교하여 Si nanowire의 경우 bandwidth 감소 및 bandgap의 증가가 나타나며, 이러한 경향은 nanowire 지름이 커질수록 점진적으로 약화됨을 알 수 있었다.

• ETRI Journal
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• 제24권3호
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• pp.221-225
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• 2002

We performed nonlinear transmission measurements and quantum-chemical calculations on dithienothiophene(DTT)-based molecules to gain insight into the effect of acceptor and donor groups on two-photon absorption(TPA) properties. The TPA intensity showed dispersion characteristics of the single-photon absorption spectrum. When the molecules included an asymmetric donor-acceptor pair, the single- and two-photon absorption maximum wavelengths were red-shifted more than when the molecules had a symmetric donor-donor structure. We interpreted this result as indicating that the $S_2$ state plays the dominating role in the absorption process of molecules with a symmetric structure. The experimental TPA ${\delta}$ values at the absorption peak wavelength showed a dependence on the structural variations. We found the self-consistent force-field theory and Hartree-Fock Hamiltonian with single configuration interaction formalism to be valid for evaluating TPA ${\delta}$. Although the quantum-chemical calculations slightly underestimated the experimental ${\delta}$ values obtained from nonlinear trans -mission measurements, they reasonably predicted the dependence of the ${\delta}$ value on the structural variations. We confirmed the role of molecular symmetry by observing that donor-donor substituted structure gave the highest experimental and theoretical TPA ${\delta}$ values and that the donor-acceptor substituted structure showed a greater red-shift in the TPA absorption maximum wavelength. Overall, the theoretical ${\delta}$ values of DTT-based molecules were in the order of $10^{-46}\;cm^4{\cdot}s{\cdot}photon^{-1}$ and are higher than that of AF-50 by nearly two orders of magnitude.

• 응용통계연구
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• 제11권1호
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• pp.177-184
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• 1998

일반적인 판별분류분석은 자료점들간의 독립성 가정을 기본 전제로 한다. 본 연구에서는 자료점 간의 종속구조를 반영하는 판별분류기준을 제안하였으며 이를 위하여 조건부 자기 로지스틱(conditional autologistic) 모형을 이용하였다. 또한 모의실험을 통해 제시된 기준을 기존의 방법과 비교하였다.

• Communications for Statistical Applications and Methods
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• 제9권2호
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• pp.533-542
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• 2002

In this paper, a covariate adjusted logrank test is considered for censored paired data under the Cox proportional hazard model. The proposed score test resembles the adjusted logrank test of Tsiatis, Rosner and Tritchler (1985), which is derived from the partial likelihood. The dependence structure for paired data is accommodated into the test statistic by using' sum of square type' variance estimators. Several weight functions are also considered, which produce a class of covariate adjusted weighted logrank tests. Asymptotic normality of the proposed test is established and simulation studies with moderate sample size show the proposed test works well, particularly when there are dependence structure between treatment and covariates.

• Journal of the Korean Statistical Society
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• 제29권2호
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• pp.201-217
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• 2000

The method of generalized estimating equations (GEE) has become very popular for the analysis of longitudinal data. We extend this work to the use of M-estimators; the resultant regression estimates are robust to heavy tailed errors and to outliers. The proposed method does not require correct specification of the dependence structure between observation, and allows for heterogeneity of the error. However, an estimate of the dependence structure may be incorporated, and if it is correct this guarantees a higher efficiency for the regression estimators. A goodness-of-fit test for checking the adequacy of the assumed M-estimation regression model is also provided. Simulation studies are conducted to show the finite-sample performance of the new methods. The proposed methods are applied to a real-life data set.

• 대한전기학회논문지
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• 제33권4호
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• pp.157-163
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• 1984

The object of this paper is to investigte the gate controlled diode structure for ionic concentration measurement. It includes device fabrication, characterization, device physics and modeling of the gate controlled diode structure. The differences of turn on voltages and surface generation currents in the (100) and (111) silicon crystallographic orientation of the sample device were observed. Therefore the dependence of these two factors of the silicon crystallographic orientation was investigated. It was observed that drifts arose after extended immersion of the sample device in acid or base solutions. The surface generation-recombination velocity of both (100) and (111) increased. The increase in the interfacial traps for both surface, determined by the turn on voltage was directly proportional to the surface generation-recombination velocity increase.