• Title/Summary/Keyword: Out-diffusion

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New Fabrication Method of $Ti:LiNbO_3$ Waveguide with Suppressed Out-Diffusion ($Li_2O$의 삼출이 없는 $LiNbO_3$ 광도파로의 제조방법)

  • 김상혁;김상국;조재철;최상삼
    • Korean Journal of Optics and Photonics
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    • v.2 no.3
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    • pp.149-152
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    • 1991
  • We report a new method of fabricating a Ti:LiNb03 waveguide with no out-diffusion by coating the waveguide with $SiO_2$ thin film. It was coated before diffusion process, and the $LiO_2$ out-diffusion was prevented in the diffusion process. We compare the near field patterns of the guided modes between the typical waveguide and the waveguide fabricated by new method proposed here.

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A Study on Liquid Phase Diffusion Bonding of STS304 using Cu-Mn-Si Insert alloy (Cu-Mn-Si Insert 합금을 이용한 스테인리스강의 액상확산접합에 관한 연구)

  • 임종태;안상욱
    • Journal of Welding and Joining
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    • v.15 no.4
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    • pp.136-142
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    • 1997
  • In this study, the amorphous foil filler, thickness of 20 - $20~30\mu\textrm{m}$ was made to develop Cu-7.5wt%Mn-7.5wt%Si insert alloy(melting point temperature : solidus line 1003K, liquidus line 1070K). Liquid phase diffusion bonding of 304 stainless steels (STS304), is carried out successfully by using developed Cu-7.5Mn-7.5Si insert alloy. Bonding conditions are taken from bonding pressure of 5MPa, bonding temperatures from 1073K to 1423K varied within 50K and brazing holding times of 0, 30, 60 and 240 minutes. As the results, the tensile strength in the liquid phase diffusion bonding is a little bit lower than that in the solid phase diffusion bonding. The authors find out that the liquid phase diffusion bonding needs lower bonding pressure than the others. Therefore, the liquid phase diffusion bonding had an excellent brazability in which the bonding process showed the typical mechanism of diffusion bonding. In corresponding, the new developed insert alloy of low melting pointed Cu-7.5Mn-7.5Si makes possible brazing between the STS304.

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A study on the impacts of informal networks on knowledge diffusion in knowledge management

  • Choi, Ha-Nool;Yang, Keun-Woo
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2008.10a
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    • pp.329-341
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    • 2008
  • Knowledge management has garnered attention due to its role of maintaining competitive advantage. Creating and sharing knowledge is an essential part of managing knowledge. However, the best knowledge is underutilized because employees tend to seek knowledge through their informal networks, not reach out to other sources for obtaining the best knowledge. Prior studies on informal networks pointed out a negative influence of heavy reliance on learning through informal networks but they paid little attention to a structure of informal networks and its impacts on diffusion of knowledge. The aim of our study is to show impacts of informal network on knowledge management by employing a network structure and investigating diffusion of knowledge within it. Our study found out that performance of learning becomes lower in a highly clustered network. Creating random links such as serendipitous learning can improve performance of knowledge management. When employees rely on a knowledge management system, creating random links is not necessary. Costs of adopting knowledge affect performance of knowledge management.

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Pollutant Emission Characteristics of Double-Concentric Diffusion Flame (이중 확산 연소장에서의 오염물질 배출 특성)

  • 김종현;이근오;이창언
    • Journal of the Korean Society of Safety
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    • v.17 no.3
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    • pp.43-49
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    • 2002
  • The NOx emission characteristics of double-concentric diffusion flames and normal diffusion flames fueled with CH$_4$ were studied. Experimental and numerical investigations were carried out for double-concentric diffusion flame with varying central air flow rate and normal diffusion flame. The Emission indices of NOx(EINOx) were measured by chemiluminescent method and calculated by numerical model based on detailed chemistry. From the comparison between double-concentric diffusion flames and normal diffusion flames, the results show that EINOx of double-concentric diffusion flames are lower than normal diffusion flame, because of Prompt EINOx was decreased. EINOx of double-concentric diffusion flames increase with central air flow rate increasing.

Formation of $P^+-Layer$ in GaAs Using the Open-Tube Diffusion of Zn (Open-Tube에서 Zn확산을 이용한 GaAs에의 $p^+$층 형성)

  • 심규환;강진영;민석기;한철원;최인훈
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.8
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    • pp.959-965
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    • 1988
  • Zinc diffusion characteristics and its applicabilities have been studied using an open-tube system. Thermal decomposition of arsenide(As) at gallium arsenide(GaAs) wafer surface was well inhibited by using Ga: poly-GaAs: Zn compositon as a diffusion source. Junction depth was obtained as 4.6x10**7\ulcorner exp)-1.25/kT) where activation energy of diffusion was 1.25eV. From Boltzmann-matano analysis, it could be identified that concentration dependencies of Zn diffusivity well consisted with those of kick-out model. The ideality factor of p+-n junction formed by Zn diffusion was about 1.6 and infrared light intensity was linearly varied in the range of sixty folds. It is concluded frodm these results that Zn diffuses according to kick-out model, and open-tube method is applicable to compound semiconductor devices.

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Characteristics of Proton-Diffused $LiNbO_3$ Optical Waveguides with Self-Aligned $SiO_2$-Cladding (자기정렬된 $SiO_2$ 클래딩 구조를 갖는 양자확산 $LiNbO_3$ 광도파로의 특성)

  • Son, Yung-Sung;Lee, Hyung-Jae;Shin, Sang-Yung
    • Proceedings of the KIEE Conference
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    • 1989.07a
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    • pp.655-658
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    • 1989
  • The characteristics of proton-diffused $LiNbO_3$ optical waveguides with self-aligned $SiO_2$-cladding are reported. When the proton diffusion occurs, the $SiO_2$-cladding limits the lateral diffusion of protons by out-diffusion of protons in unclad region. Proton indiffusion in depth direction is promoted by inhibition of out-diffusion in clad region. Consequently, the mode profile in depth direction can be nealy symmetric. The extent of the proton exchange was observed by measuring the infrared absorption peak at about $3500cm^{-1}$. It is confirmed that proton diffusion with $SiO_2$-cladding has structural excellency.

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Computer Simulation on the Thermal Environment by the Diffusion temperature and Diffusion Angle of Ceiling Type Air Conditioner in Classroom (교실에서의 천장형 냉난방기의 취출온도 및 취출각도에 따른 열환경 시뮬레이션)

  • Park, Hyo-Soon;Park, Seung-Ik;Lee, Sang-Hyeok;Lee, Kam-Gyu
    • The Journal of Sustainable Design and Educational Environment Research
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    • v.4 no.4
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    • pp.1-18
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    • 2004
  • Research has been carried out to study thermal environment in a classroom under three kinds of air diffusion temperature and six kinds of air diffusion direction for ceiling type air conditioner. The velocity and temperature distributions of air in the room calculated by 3-dimensional numerical method(PHOENICS), This present study was also conducted to calculate the Air Diffusion Performance Index(ADPI) for cooling conditions and Predicted Percentage of Dissatisfied(PPD) for heating conditions. This analysis shows that the optimum angle of ceiling type air conditioner's diffusion is $15{\sim}30^{\circ}$ for cooling mode and about $15{\sim}45^{\circ}$ for heating mode in these calculating conditions. And also analysis has been carried out to evaluate thermal comfort of vertical and horizontal cross section of classroom.

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Impurity Diffusion Enhancement of Interdiffusion in GalnAsP Heterostructures Lattice Matched to GaAs and InP (GaAs와 InP에 격자정합된 GaINAsP 이중조직에서 불순물 확산에 의한 상호확산 촉진)

  • Park, Hyo-Hun;Lee, Gyeong-Ho;Nam, Eun-Su;Lee, Yong-Tak
    • ETRI Journal
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    • v.11 no.4
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    • pp.84-97
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    • 1989
  • The influence of Zn, Si and Te diffusion on the interdiffusion in $GaAs-Ga_1_-xIN_xAs_1__yP_y$and InP$Ga_1__xIn_xAs_1__yP_y$ heterostructures was studied. The heterostructures were grown by liquid phase epitaxy, and the impurity diffusion into the heterostructures was carried out using metal compound or element sources. The extent of interdiffusion for both group III and V atoms was observed by depth profiling of matrix elements with secondary ion mass spectrometry and Auger electron spectroscopy. Selective enhancement of cation interdiffusion was observed by the concurrent Zn diffusion in both the GaAs based-and InP based-crystals. In contrast to the Zn diffusion, the Si diffusion in the GaAs based-crystal and the Te diffusion in the InP based-crystal enhanced both cation and anion interdiffusion to the same extent. A kick-out mechanism is proposed to explain the selective enhancement of the cation interdiffusion due to Zn, and a single vacancy mechanism is proposed for the interdiffusion due to Si and Te.

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Accelerated Chloride Diffusion Properties of Portland Cement Concrete (포틀랜드계 시멘트 콘크리트의 촉진 염화물 확산 특성)

  • 김진철;이찬영;이용은
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.775-778
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    • 1999
  • Accelerated chloride diffusion tests were carried out to estimate the chloride diffusion coefficient of concrete using ordinary portland cement, low heat belite-rich portland cement, and sulphate resistant portland cement. Concrete using low heat belite-rich portland cement showed a high diffusion coefficient due to delayed hydration of low heat belite rich portland cement, while the diffusion coefficients of concrete using sulphate resistant portland cement and ordinary portland cement were low.

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Two Dimensional Chloride Ion Diffusion in Reinforced Concrete Structures for Railway

  • Kang, Bo-Soon;Shim, Hyung-Seop
    • International Journal of Railway
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    • v.4 no.4
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    • pp.86-92
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    • 2011
  • Chloride ion diffusion at the corner of rectangular-shaped concrete structures is presented. At the corner of rectangular-shaped concrete, chloride ion diffusion is in two-dimensional process. Chloride ions accumulate from two orthogonal directions, so that corrosion-free life of concrete structures is significantly reduced. A numerical procedure based on finite element method is used to solve the two-dimensional diffusion process. Orthotropic property of diffusion coefficient of concrete is considered and chloride ion profile obtained from numerical analysis is used to produce transformed diffusion coefficient. Comparisons of experimental data are also carried out to show the reliability of proposed numerical analysis. As a result of two-dimensional chloride diffusion, corrosion-free life of concrete structure for railway is estimated using probability of corrosion initiation. In addition, monographs that produces transformed diffusion coefficient and corrosion-free life of concrete structure are made for maintenance purpose.

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