• 기술혁신연구
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• 제13권1호
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• pp.113-139
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• 2005

The purpose of this study is to analyse the diffusion process of personal computer (PC) in Korea during the 1990's. To achieve the goal, five research steps have been done such as the literature survey of diffusion theory, set-up of theoretic equilibrium model of supply and demand, derivation of an equilibrium path using Hamiltonian, and empirical analysis. The empirical analysis has been performed based on that equilibrium path. The results can be summarized as follows : First, technological attribute of diffusing product influences the diffusion speed of Product. It has been proven that the size of the network has a significant effect on the diffusion of PC in empirical study Second, supply factors have an important role in the diffusion process. According to the empirical analysis, decreasing cost of production as a result of technological advance promotes the speed of diffusion. This point seems to be manifest theoretically, but existing empirical models have not included supply factors explicitly, Third, it has been found out that expectation of decreasing cost would influence the speed of diffusion negatively as expected ex ante. Theoretically this result is supported by arbitrage condition of purchasing timing.

• Asia pacific journal of information systems
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• 제7권3호
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• pp.89-108
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• 1997

This study, drawing upon research in innovation theory and Information systems, investigates the relationship among the organizational and innovation characteristics and the extent of internal and external diffusion of EDI in Korean firms. The data for this study were collected from 131 firms that have implemented EDI. The results of the correlation and the multiple regression analysis show that elapsed time and organizational compatibility are the major predictors of EDI diffusion. Specifically, the extent of communication, elapsed time and organizational compatibility are the major predictors of internal diffusion, while centralization, organizational compatibility and elapsed time are closely related to external diffusion of EDI. The results of this study imply that to facilitate the use of EDI widely within and beyond organizations, EDI system should be compatibile with the organizational tasks, values systems and existing information systems.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.124-127
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• 1995

Due to the self-diffusion of nuclear spins, the edge of phantoms is enhanced in the magnetic resonance imaging (MRI), especially in the case of microscopy [1]. According to several published works, theory has been established that the edge enhancement is caused by the motion narrowing around bounded regions due to diffusions of nuclear spins during data acquisition. It is found, however, that the signal decreases due to the diffusion attenuation and image is distorted as edge of the image is sharpened. In this paper, we wilt investigate this signal loss during data acquisition and its effects on image, i.e., image edge enhancement due to the diffusion phenomenon. This result is new and different from the previously discussed edge enhancement due to the diffusion, namely, by motion narrowing effect or spin bouncing effect at the boundary.

• 한국표면공학회지
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• 제36권1호
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• pp.99-107
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• 2003

The diffusion coefficient of Xe-133 was obtained from an annealing test. The specimens were made from a UO$_2$ single crystal powder with natural enrichment. Weight and grain size were 300mg and ($23\mu\textrm{m}$, respectively. Oxygen potentials were obtained from an oxygen sensor. Released fractions were obtained from both results of gamma scans and quantitative analysis with MCNP code, The annealing test was performed at three temperatures at once. Diffusion coefficients of Xe-133 were calculated using slope of Booth theory in each O/M ratios. Activation energy and the pre-exponential factor of the diffusion coefficient were obtained. The activation energy of near stoichiomeric $UO_2$ is 310 kJ/mol. The measured values of near stoichiometric $UO_2$ are very close to other data available. Diffusion coefficients increase with hyper-stoichiometry, due to higher concentration of cation vacancies.

• 한국분말재료학회지
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• 제7권3호
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• pp.137-142
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• 2000

In order to analyze the densification behaviour of stainless steel powder compacts during hot isostatic pressing (HIP) at elevated temperatures, a power-law creep constitutive model based on the plastic deformation theory for porous materials was applied to the densification. Various densification mechanisms including interparticle boundary diffusion, grain boundary diffusion and lattice diffusion mechanisms were incorporated in the constitutive model, as well. The power-law creep model in conjunction with various diffusion models was applied to the HIP process of 316L stainless steel powder compacts under 50 and 100 MPa at $1125^{\circ}C$. The results of the calculations were verified using literature data. It could be found that the contribution of the diffusional mechanisms is not significant under the current process conditions.

• 품질경영학회지
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• 제43권3호
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• pp.421-438
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• 2015

Purpose: The purpose of this study was to grasp the level of effects innovative features and quality of the appliance system on organizational performance and ultimately analyze the willingness of the IT staff to adopt an appliance system. Methods: The survey was conducted on 350 vendors' clients and partners who currently use an appliance system from March to May 2014. A total of 331 effective questionnaires were collected and analyzed using PASW18 and SmartPLS. Results: The results show that relative advantage, facilitating condition and trialability and quality factors all had an effect on organizational performance expectations. Further, when an appliance system is adopted, it was shown that cost and reliability emphasized by a vendor did not produce any significant effects on organizational performance expectations. Conclusion: This study is significant as it is the first to combine such models as Innovation Diffusion Theory, Information Systems Success Model, and Unified Theory of Acceptance and Use of Technology with a new external variable. In addition, it illustrated how variables affect the adoption of an appliance system such as a new innovation system.

• 대한기계학회논문집
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• 제18권2호
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• pp.432-445
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• 1994

From a theoretical analysis point of view, the 2-stage precipitator is decomposed into two units: charging cell and collecting cell. Collection efficiency predictions of the two-stage parallel-plate electrostatic precipitator have been performed theoretically incorporating with the charging and the collecting cells. Particle trajectorise passing the charging cell have been modeled as a simple one. Particle charge distribution at the outlet of the charging cell is calculated through integration of the present unipolar combined charging rate along the entire particle trajectory, and average charge of particles at the outlet of the charging cell is obtained from the particle charge distribution. As for the collecting cell, the diminution of particle concentration along the longitudinal direction of the collecting cell is investigated considering the conventional Deutsch's theory and the laminar theory. One should note that the collection efficiency formula derived is based on monodisperse aerosols. It has been confirmed through the analysis that predictions of particle charge by applying White's unipolar diffusion charging theory overpredict actual cases in the continuum regime, while predictions by Fuch's unipolar diffusion charging theory indicate the reasonable result in the same regime. Theoretical predictions of collection efficiency are also compared with the available experimental results. Comparisons show that the experimental results are consistently located in the collection efficiency region bounded by the two limits, the Deutsch and the laminar collection efficiencies. Finally design parameters of the 2-stage electrostatic precipitator have been investigated systematically through the one-variable-at-a-time method in terms of collection efficiency. Applied voltages on the corona wire of the charging cell and the plate of the collecting cell, and the average air velocity have been selected as the design parameters.

• 한국전자거래학회지
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• 제20권3호
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• pp.11-28
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• 2015

스마트폰의 일상화로 모바일 중심의 라이프 스타일이 확산되면서, 모바일을 기반으로 하는 모바일 뱅킹, 쇼핑 등의 이용이 증가하고 있다. 또한 최근 금융과 IT기술이 결합된 신조어인 Fintech(Financial + Technology)의 등장과 함께, IT기반의 금융시장은 더 확대될 것으로 보인다. 이러한 추세에 따라서, 지급결제 수단으로서의 모바일 신용카드에 대한 기업 및 국가적 차원의 관심 및 투자가 증가하고 있으나, 소비자의 실제적인 확산 및 이용은 낮은 수준에 있다. 이러한 점을 고려하여 본 연구에서는 모바일 신용카드 이용 및 확산을 위한 요인이 무엇인지를 파악하기 위하여 확산이론(Innovation Diffusion Theory)과 후기수용모형(Post Acceptance Model)을 바탕으로 연구모형을 구성하였다. 설문조사를 통해 분석 자료를 수집하고, 연구모형을 분석한 결과, 인지된 용이성, 이미지, 적합성, 촉진의 4가지 요인이 사용자 만족에 유의한 영향을 미치는 것이 확인되었다. 또한, 모바일 신용카드에 대한 사용자 만족은 모바일 신용카드 지속사용의도에 유의한 영향을 미치는 것으로 나타났다. 또한 집단 간 비교연구에서는 플라스틱 신용카드보다 모바일 신용카드 이용금액이 많은 집단에서 촉진이 사용자 만족에 더 큰 영향을 미치는 것으로 나타났으며, 상대적으로 모바일카드 이용금액이 적은 집단에서는 인지된 용이성과 이미지가 사용자 만족에 더 큰 영향을 미치는 것으로 나타났다. 본 연구결과는 모바일 신용카드 활성화를 위한 정부 및 기업의 마케팅에 있어서의 전략적 가이드라인을 제공할 것으로 기대하며, 또한 상대적으로 부족한 모바일 신용카드 연구에 초기 단계 연구로서의 가치를 지닐 것으로 기대한다.

• 한국경영과학회지
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• 제38권1호
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• pp.201-216
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• 2013

Diffusion is a basic mathematical tool for modern financial engineering. The theory of the estimation methods for diffusion models is an important topic of the financial engineering. Many researches have been tried to apply the likelihood estimation method for estimating diffusion models. However, the likelihood estimation method for diffusion is complicated and needs much amount of computing. In this paper we develop the estimation methods which are simple enough to be compared to the Euler approximation method, and efficient enough statistically to be compared to the likelihood estimation method. We devise pseudo-likelihood and propose the maximum pseudo-likelihood estimation methods. The pseudo-likelihoods are obtained by approximating the transition density with normal distributions. The means and the variances of the distributions are obtained from the delta expansion suggested by Lee, Song and Lee (2012). We compare the newly suggested estimators with other existing estimators by simulation study. From the simulation study we find the maximum pseudo-likelihood estimator has very similar properties with the maximum likelihood estimator. Also the maximum pseudo-likelihood estimator is easy to apply to general diffusion models, and can be obtained by simple numerical steps.

• Bulletin of the Korean Chemical Society
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• 제8권3호
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• pp.196-200
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• 1987

A nonlinear theory presented previously is applied to the Oregonator, which is a model for the Belousov-Zhabotinskii reaction, to study instability near the critical point driven by diffusions. The result shows that the theory may be applied to an actual system.