• Computers and Concrete
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• 제10권3호
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• pp.219-229
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• 2012

Carbonation is a widespread degradation of concrete and may be coupled with more severe degradations. An experimental investigation was carried out to study the effect of carbonation on chloride ion diffusion of concrete. The characteristic of concrete after carbonation was measured, such as carbonation depth, strength and pore structure. Results indicated that carbonation depth has a good linear relation with square root of carbonate time, and carbonation can improve compressive strength, but lower flexural strength. Results about pore structure of concrete before and after carbonation have shown that carbonation could cause a redistribution of the pore sizes and increase the proportion of small pores. It also can decrease porosities, most probable pore size and average pore diameters. Chloride ion diffusion of concrete after carbonation was studied through natural diffusion method and steady state migration testing method respectively. It is supposed that the chloride ion concentration of carbonation region is higher than that of the sound region because of the separation of fixed salts, and chloride ion diffusion coefficient was increased due to carbonation action evidently.

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.192-198
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• 1996

We present a theoretical formulation of diffusion process on solid surface based on multidimensional transition state theory (TST). Surface diffusion of single adatom results from hopping processes on corrugated potential surface and is affected by surface vibrations of surface atoms. The rate of rare events such as hopping between lattice sites can be calculated by transition state theory. In order to include the interactions of the adatom with surface vibrations, it is assumed that the coordinates of adatom are coupled to the bath of harmonic oscillators whose frequencies are those of surface phonon modes. When nearest neighbor surface atoms are considered, we can construct Hamiltonians which contain terms for interactions of adatom with surface vibrations for the well minimum and the saddle point configurations, respectively. The escape rate constants, thus the surface diffusion parameters, are obtained by normal mode analysis of the force constant matrix based on the Hamiltonian. The analysis is applied to the diffusion coefficients of W, Ir, Pt and Ta atoms on the bcc(110) plane of W in the zero-coverage limit. The results of the calculations are encouraging considering the limitations of the model considered in the study.

• Journal of Korean Vacuum Science & Technology
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• 제1권1호
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• pp.30-37
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• 1997

Interactions of Cu films with Si substrates separated by thin layers of molybdenum and molybdenum nitride were investigated in the viewpoint of diffusion barrier to copper. the diffusion barrier behavior of the layers was studied as functions of deposition and annealing conditions by cross-sectional transmission electron microscopy and Nomarski microscopy. the layers deposited at $N_2$ gas ratios of 0.4 and 0.5 exhibited good diffusion barrier behaviors up to $700^{\circ}C$, mainly due to the phase transformation of molybdenum to $\gamma$-Mo$_2$N phase. The increase in the N gas ratio in deposition elevates the lower limit of barrier failure temperature. Futhermore, amorphous molybdenum nitride films deposited at 20$0^{\circ}C$ and 30$0^{\circ}C$ did not fail, while the crystalline $\gamma$-Mo$_2$N films deposited at 40$0^{\circ}C$ and 50$0^{\circ}C$ showed signs of interlayer interactions between Cu and Si after annealing at 75$0^{\circ}C$ for 30 minutes. Therefore, the amorphous nature of the molybdenum nitride layer enhanced its ability to reduce Cu diffusion and its stability as a diffusion barrier at elevated temperatures.

• Computers and Concrete
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• 제19권2호
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• pp.211-216
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• 2017

Crack on concrete surface allows more rapid penetration of chlorides. Crack width and depth are dominant parameters for chloride behavior, however their effects on chloride penetration are difficult to quantify. In the present work, the previous anisotropic (1-D) model on chloride diffusion in concrete with single crack is improved considering crack shape and roughness. In the previous model, parallel-piped shape was adopted for crack shape in steady-state condition. The previous model with single crack is improved considering wedge shape of crack profile and roughness. For verifying the proposed model, concrete samples for nuclear power plant are prepared and various crack widths are induced 0.0 to 1.2 mm. The chloride diffusion coefficients in steady-state condition are evaluated and compared with simulation results. The proposed model which can handle crack shape and roughness factor is evaluated to decrease chloride diffusion and can provide more reasonable results due to reduced area of crack profile. The roughness effect on diffusion is evaluated to be 10-20% of reduction in chloride diffusion.

• 한국재료학회지
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• 제5권2호
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• pp.169-177
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• 1995

Cu와 Si사이의 확산방지막으로 1000$\AA$ 두께의 TiN의 특성에 대하여 면저항 측정, 식각패임자국 관찰, X선 회절, AES, TEM 등을 이용하여 조사하였다. TiN 확산방지막은 $550^{\circ}C$, 1시간의 열처리 후에 Cu의 안쪽 확산으로 인해 Si(111)면을 따라 결정결함(전위)을 형성하고, 전위 주위에 Cu 실리사이드로 보이는 석출물들을 형성함으로써 파괴되었다. Al의 경우와는 달리 Si 패임자국이 형성되지 안흔 것으로부터 TiN확산방지막의 파괴는 Cu의 안쪽 확산에 의해서만 일어나는 것을 알 수 있었다. 또한, Al의 경우에는 우수한 확산방지막 특성을 보여주었던 충진처리된 TiN가 Cu의 경우에는 거의 효과가 없는 것을 알 수 있었다. 이것은 Al의 경우에는 TiN의 결정립계에 존재하는 $TiO_{2}$가 Al과 반응하여 $Al_{2}O_{3}$를 형성함으로써 Al의 확산을 방해하는 화학적 효과가 매우 크지만, Cu의 경우에는 CuO 또는 $Cu_{2}O$와 같은 Cu 산화물은$TiO_{2}$에 비해서 열역학적으로 불안정하기 때문에 이러한 화학적 효과를 기대할 수 없으며, 따라서 충진처리 효과가 거의 없는 것으로 이해된다.

• 한국철도학회논문집
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• 제19권4호
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• pp.539-546
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• 2016

본 연구에서는 개통 12년을 맞는 한국고속철도(KTX, Korea Train eXpress)를 대상으로 여객수요 증가 에 대해 새로운 시각에서 검증하고 이에 바탕하여 장래 KTX의 지속가능 운영방안을 고찰하고자 한다. 지속적으로 증가되고 있는 KTX 여객수요의 영향요인으로는 노선의 확대와 녹색성장을 통한 대중교통의 인식 전환 등이 될 수 있겠으나, 현재까지 KTX 관련연구는 이러한 점을 고려하지 못한 채 주로 여객수요 예측에 집중되어 왔다. 본 연구에서는 통행시간 감소로 인한 이용객의 사회적, 심리적 영향에 초점을 맞춘 요인을 고찰하였으며 이를 위해 확산이론 개념을 적용하여 여객수요 증가현상을 설명하였다. 소비자가 가지고 있는 정보가 다양한 네트워크를 통해 전파되는 현상인 확산효과는 제품선택과 구매태도에 영향을 미치는 마케팅학적 개념으로 이 영향이 KTX 이용에도 적용되어 여객수요 확산을 촉진시켰다는 가설을 설정하고 분석을 진행하였다. KTX 경부선을 대상으로 여객수요 증가에 기인하는 이용자의 사회적, 심리적 영향을 Bass의 확산모형(Diffusion Model)을 통해 분석하고 그 결과를 토대로 장래 KTX의 지속가능한 운영에 있어서 여객수요 향상을 위한 교통서비스의 마케팅적 정책추진이 가능하다는 시사점에 대해 고찰해본다.

• 한국IT서비스학회지
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• 제22권2호
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• pp.41-56
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• 2023

Metaverse is a three-dimensional virtual space where virtual and reality interact and co-evolutionize, and social, cultural, and economic activities are carried out in it to create value. Among the types of metaverse, the virtual world metaverse is expected to bring innovation beyond time and space in all areas of industry and society following the Internet. This study empirically analyzed factors affecting consumer's intention to use the virtual world metaverse by an innovation diffusion perspective. It was analyzed as an expanded technology acceptance model by setting relative advantages, ease of use, and visibility among the attributes of the innovation diffusion, and social presence, telepresence, and interactivity among the characteristics of the virtual worlds as factors. The proposed research model and hypothesis were verified through a PLS structural equation analysis based on a survey of 216 people. Studies have shown that relative advantage, telepresence, and interactivity have a significant effect on perceived usefulness and perceived enjoyment, but visibility does not have a significant effect on perceived usefulness and perceived enjoyment. It was found that ease of use had a positive effect on perceived enjoyment, social presence had a positive effect on perceived usefulness, and perceived usefulness and perceived enjoyment had a positive effect on the intention to use, respectively. This study is meaningful in that it empirically analyzed the factors affecting the intention to use the virtual world metaverse by dividing the psychological characteristics that induce consumer behavior into perceived usefulness which is an extrinsic motivation and perceived enjoyment which is an intrinsic motivation.

• 한국레이저가공학회지
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• 제4권3호
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• pp.40-44
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• 2001

Microbump formation during CO$_2$ laser texturing of glass substrates is examined in this paper. Experimental results show that different bump shapes (dome-shaped, with a central dimple, and with a peripheral rim) are generated depending on the laser fluence. A theoretical model for the process is suggested based on thermoelastic behavior but limited only to the dome-shaped bump. The dimensions (maximum height and base area) of the bump shows a logarithmic dependence on laser fluence as expected from the theory. Numerical computation reveals that the effect of thermal diffusion is not negligible for relatively long laser pulses.

• 한국건축시공학회지
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• 제9권6호
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• pp.71-78
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• 2009

하중을 고려한 염분침투성의 평가가 대단히 중요한 것으로 확인되었다. 본 연구에서는 압축응력하에서 Plain콘크리트에서는 47%정도, BFS콘크리트에서는 89%정도 증가 하는 것으로 나타났다. 무하중 상태에서 BFS를 혼입한 콘크리트의 확산계수가 BFS 무혼입 콘크리트에 비해 적은 것이 확인되었다. 이러한 영향은 압축응력이 발생하는 환경하에서도 같은 경향을 나타내었다. 압축응력이 작용하는 환경 하에서 BFS콘크리트는 Plain콘크리트와 같이 하중의 증가와 함께 확산계수가 증가하는 것으로 확인 되었다. 또한, Plain콘크리트에 비해 압축하중의 영향을 크게 받는 것으로 확인 되었다. BFS의 비표면적이 높을수록 확산 계수가 작은 것으로 확인되었고, 이러한 경향은 고응력 환경에서 현저히 나타나는 것이 확인되었다. BFS의 치환율이 증가할수록 확산계수가 작은 것이 확인되었다. 또한, 압축응력이 작용하는 환경 하에서 BFS의 치환에 의한 염분침투성의 억제 효과가 더욱 더 현저히 나타나는 것으로 확인되었다.

• 지식경영연구
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• 제12권1호
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• pp.53-76
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• 2011

This study aims to examine the effects of on premium convergence products buying behavior. This paper analyzed the positive attitude formation using the basic and extended TAM and also revealed how the positive premium convergence product attitude relate to relationship purchasing intention and word of mouth intention. The samples of 562 consumer indicate that the antecedents are consist of four dimension(perceived usefulness, perceived ease of use, social value) and attitude is developed into buying intention and word of mouth intention. We have reached the following conclusion about the antecedents and outcomes factors of customer attitude for the launch of premium convergence product. First, perceived usefulness, perceived delight, and social value had a positive effect on customer attitude but perceived ease of use did not. Second, we found that customer attitude had a positive effect on purchase intention and word-of mouth intention. Finally, interaction effect of perceived usefulness/perceived delight and social value had a positive effect on customer attitude. Our findings suggested that adoptian and diffusion of premium convergence product is influenced by several behavior factors. Managerially, our result emphasize that premium convergence products must satisfy not only the perceived usefulness/delight but also social value that consumers are seeking in order to be successful in the market. The theoretical and practical implications of these findings are discussed as well.