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검색결과 1,974건 처리시간 0.028초

NH3 분위기에서 후속 열처리에 의한 p형 ZnO 형성 (Formation of N Doped, p-type ZnO Films by Post-annealing in NH3 Ambient)

  • 정은수;김홍승;조형균
    • 한국전기전자재료학회논문지
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    • 제19권7호
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    • pp.611-617
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    • 2006
  • We report the preparation of N doped, p-type ZnO films by post-annealing in $NH_3$ ambient. The properties were examined by XRD, Hall-effect measurement, PL, and SIMS. ZnO films showed better crystallinity and electron concentration of $10^{15}-10^{17}/cm^3$ with post-annealing in $NH_3$ ambient. These films were converted to p-type ZnO by activation thermal annealing process at $800^{\circ}C$ under $N_2$ ambient. The electrical properties of the p-type ZnO showed a hole concentration of $1.06\times10^{16}/cm^3$, a mobility of $15.8cm^2/V{\cdot}s$, and a resistivity of $40.18\Omega{\cdot}cm$. The N doped ZnO films showed a strong photoluminescence peak at 3.306 eV at 13 K, which is closely related to neutral acceptor bound excitons of the p-type ZnO:N. In the SIMS spectra, the incorporation of nitrogen was confirmed.

모발(毛髮)의 Carotinoid계(係) 색소(色素) 염색(染色)에서 Chitosan 처리순서(處理順序)가 모발(毛髮)의 염색성(染色性)과 역학적(力學的) 특성(特性)에 미치는 영향(影響)

  • 김경선;전동원;김종준;안병태
    • 패션비즈니스
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    • 제11권5호
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    • pp.79-89
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    • 2007
  • The effect of chitosan treatment on the dyeing and dye fastness, and mechanical properties of hair was investigated in this study when the carotinoid dyestuffs extracted from African Marigold(Tagetes erecta L.) were applied to the hair. The sequences of the chitosan treatment were changed in dyeing and mordanting procedures, i.e., pre-treatment, mid-treatment, and post-treatment. While the effect of chitosan application on the color shade change was not significant, the pre-treatment of the chitosan increased the dye uptake. Discoloration and fading was observed in the lightfastness test when chitosan was mid-treated. Alkali perspiration and acid perspiration fastness test results showed that chitosan post-treatment gave lower tendency. Washing fastness results showed that chitosan post-treatment and mid-treatment gave lower values, which indicates that chitosan deters the direct formation of insoluble complex among fiber-dyestuff-mordant. In the mechanical characteristics results, however, initial modulus and breaking strength increased significantly in the post-treatment and pre-treatment of chitosan.

SiC 열산화막의 Electrode형성조건에 따른 C-V특성 변화 (The variation of C-V characteristics of thermal oxide grown on SiC wafer with the electrode formation condition)

  • 강민정;방욱;송근호;김남균;김상철;서길수;김형우;김은동
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 하계학술대회 논문집
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    • pp.354-357
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    • 2002
  • Thermally grown gate oxide on 4H-SiC wafer was investigated. The oxide layers were grown at l150$^{\circ}C$ varying the carrier gas and post activation annealing conditions. Capacitance-Voltage(C-V) characteristic curves were obtained and compared using various gate electrode such as Al, Ni and poly-Si. The interface trap density can be reduced by using post oxidation annealing process in Ar atmosphere. All of the samples which were not performed a post oxidation annealing process show negative oxide effective charge. The negative oxide effective charges may come from oxygen radical. After the post oxidation annealing, the oxygen radicals fixed and the effective oxide charge become positive. The effective oxide charge is negative even in the annealed sample when we use poly silicon gate. Poly silicon layer was dope by POCl$_3$ process. The oxide layer may be affected by P ions in poly silicon layer due to the high temperature of the POCl$_3$ doping process.

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Thermo-mechanical postbuckling of symmetric S-FGM plates resting on Pasternak elastic foundations using hyperbolic shear deformation theory

  • Chikh, Abdelbaki;Bakora, Ahmed;Heireche, Houari;Houari, Mohammed Sid Ahmed;Tounsi, Abdelouahed;Bedia, E.A. Adda
    • Structural Engineering and Mechanics
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    • 제57권4호
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    • pp.617-639
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    • 2016
  • In this work, an analytical formulation based on both hyperbolic shear deformation theory and stress function, is presented to study the nonlinear post-buckling response of symmetric functionally graded plates supported by elastic foundations and subjected to in-plane compressive, thermal and thermo-mechanical loads. Elastic properties of material are based on sigmoid power law and varying across the thickness of the plate (S-FGM). In the present formulation, Von Karman nonlinearity and initial geometrical imperfection of plate are also taken into account. By utilizing Galerkin procedure, closed-form expressions of buckling loads and post-buckling equilibrium paths for simply supported plates are obtained. The effects of different parameters such as material and geometrical characteristics, temperature, boundary conditions, foundation stiffness and imperfection on the mechanical and thermal buckling and post-buckling loading capacity of the S-FGM plates are investigated.

SNS 사용자들의 사회적 라포 현상 연구 (A Study on Social Rapport Phenomenon of Social Network Services Users)

  • 안창민;권순재;정현희
    • 지식경영연구
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    • 제19권1호
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    • pp.41-57
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    • 2018
  • While there are lots of studies on examining the effects of social rapport in many research areas, however, there is a little work in examining the effect of the social rapport in social network service (SNS) contexts. Thus, this study attempts to examine the effect of social rapport in SNS settings. To address the research questions, this study has presented its hypotheses and conducted three experimental approaches by collecting 180 data from student subjects who have prior experiences on using SNSs to verify the hypotheses. This study has examined three experiments the effects of characteristics of Facebook(i.e. the number of mutual friends, the number of post likes, and the post personalities) on the social rapport and user responses. This study has conducted two-way ANOVA to verity its proposed research hypotheses. Based on three experiments, this study found that both the effects of the number of post likes and the number of post likes on the social rapport were not significant. Based upon empirical findings, this study has demonstrated how the effects of social rapports in SNSs were different from those of previous studies, and brought more attentions to the relevant literature.

횡하중을 받는 말뚝의 Beam-Column 해석 (A Beam-Column Analysis of Laterally Loaded Piles)

  • 백원진;이강일;이진수;김주현;송병관
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2008년도 추계 학술발표회
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    • pp.1212-1217
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    • 2008
  • In this study, in order to clarify the effect of the direction of cyclic shear on the post-earthquake settlement the multi-directional shear tests were carried out for Toyoura Japan standard sand, Genkai natural sand and the Granulated Blast Furnace Slag (GBFS). In a series of tests, number of strain cycles was changed as n=5-200 and the shear strain amplitude varied from 0.1% to 1.0%. The relative density was also changed as Dr=50, 60 and 70%. From the test results for Toyoura sand and GBFS, it is clarified that the post cyclic settlement is relatively large at the small relative density and becomes large with the shear strain amplitude. When the influence of the direction of cyclic shear is decreases, the post cyclic settlement strain for Toyoura sand is converged to a constant value, but the GBFS is increased with the number of strain cycles.

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HoMnO3 박막의 강유전 특성의 결정상 의존성 (Dependence of Ferroelectric Properties on the Crystalline Phases of HoMnO3 Thin Film)

  • 김응수;강동호
    • 한국재료학회지
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    • 제16권6호
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    • pp.394-399
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    • 2006
  • Ferroelectric $HoMnO_3$ thin films were deposited on the Si(100) substrate at $700^{\circ}C$ for 2 hrs by metalorganic chemical vapor deposition (MOCVD) and post-annealed at 850oC by rapid thermal process (RTP). Electrical properties and crystalline phases of $HoMnO_3$ thin films were investigated as a function of postannealing time. Single phase of hexagonal symmetry with c-axis preferred orientation was obtained from $HoMnO_3$ thin films post-annealed at $850^{\circ}C$ for 5 min, while the c-axis preferred orientation was decreased with the increase of post-annealing time, and the thin films post-annealed at $850^{\circ}C$ for 15 min showed the mixture phases of hexagonal and orthorhombic symmetry. P-E (Polarization-Electric field) hysteresis loop of ferroelectric $HoMnO_3$ thin films was observed only for the single phase of hexagonal symmetry, but that was not observed for the mixture phases of the hexagonal and orthorhombic symmetry, which was discussed with the bond valence of Mn ion of crystalline phase. Leakage current density was dependent on the microstructure of thin films as well as the change of valence of Mn ion.

Numerical analysis of thermal post-buckling strength of laminated skew sandwich composite shell panel structure including stretching effect

  • Katariya, Pankaj V.;Panda, Subrata Kumar
    • Steel and Composite Structures
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    • 제34권2호
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    • pp.279-288
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    • 2020
  • The computational post-buckling strength of the tilted sandwich composite shell structure is evaluated in this article. The computational responses are obtained using a mathematical model derived using the higher-order type of polynomial kinematic in association with the through-thickness stretching effect. Also, the sandwich deformation behaviour of the flexible soft-core sandwich structural model is expressed mathematically with the help of a generic nonlinear strain theory i.e. Green-Lagrange type strain-displacement relations. Subsequently, the model includes all of the nonlinear strain terms to account the actual deformation and discretized via displacement type of finite element. Further, the computer code is prepared (MATLAB environment) using the derived higher-order formulation in association with the direct iterative technique for the computation of temperature carrying capacity of the soft-core sandwich within the post-buckled regime. Further, the nonlinear finite element model has been tested to show its accuracy by solving a few numerical experimentations as same as the published example including the consistency behaviour. Lastly, the derived model is utilized to find the temperature load-carrying capacity under the influences of variable factors affecting the soft-core type sandwich structural design in the small (finite) strain and large deformation regime including the effect of tilt angle.

MODIFICATION OF INITIALLY GROWN BN LAYERS BY POST-N$^{+}$ IMPLANTATION

  • Byon, E-S.;Lee, S-H.;Lee, S-R.;Lee, K-H.;Tian, J.;Youn, J-H.;Sung, C.
    • 한국표면공학회지
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    • 제32권3호
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    • pp.351-355
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    • 1999
  • BN films with a high content of cubic phase has been deposited by a variety of techniques. It is well known that c-BN films grow with a unique microstructure consisting of $sp^2$ and $sp^{3-}$ bonded layers. Because of existence of the initially grown $sp^{2-}$ /bonded layer, BN films are not adhesive to the substrates. In this study, post-N$^{+ }$ / implantation was applied to improve the adhesion of the films. A Monte Carlo program TAMIX was used to simulate this modification process. The simulation showed nitrogen concentration profile at $1200\AA$ in depth in case of 50keV -implantation energy. FTIR spectra of the $N^{+}$ implanted specimens demonstrated a strong change of absorption band at 1380 cm$^{ -1 }$The films were also investigated by HRTEM. From these results, it is concluded that the post ion implantation could be an effective technique which improves the adhesion between BN film and substrate.

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Outcomes of Gastrectomy for Gastric Cancer in Patients Aged >80 Years: A Systematic Literature Review and Meta-Analysis

  • Zelalem Chimdesa Merga ;Ji Sung Lee ;Chung-Sik Gong
    • Journal of Gastric Cancer
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    • 제23권3호
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    • pp.428-450
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    • 2023
  • This meta-analysis examined the surgical management of older patients (>80 years) with gastric cancer, who were often excluded from randomized controlled trials. We analyzed 23 retrospective cohort studies involving 18,372 patients and found that older patients had a higher in-hospital mortality rate (relative risk [RR], 3.23; 95% confidence interval [CI], 1.46-7.17; P<0.01) and more post-operative complications (RR, 1.36; 95% CI, 1.19-1.56; P<0.01) than did younger patients. However, the surgical complications were similar between the two groups. Older patients were more likely to undergo less extensive lymph node dissection and longer hospital stays. Although older patients had statistically significant post-operative medical complications, they were not deprived of surgery for gastric cancer. The comorbidities and potential risks of post-operative complications should be carefully evaluated in older patients, highlighting the importance of careful patient selection. Overall, this meta-analysis provides recommendations for the surgical management of older patients with gastric cancer. Careful patient selection and evaluation of comorbidities should be performed to minimize the risk of post-operative complications in older patients, while recognizing that they should not be deprived of surgery for gastric cancer.