• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.241-249
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• 1999

Soot particle temperatures in co-flow diffusion flames have been measured using a two-color pyrometry at the pressure of 0.2 MPa(2 atm). The measured soot particle temperatures along with the integrated soot volume fractions are analyzed to understand soot formation characteristics. At 0.2 MPa, the addition of small amount of air into ethylene do not change the soot particle temperature in soot formation regions. This result showed that the increase of soot formation with addition of air is mostly due to the chemical effect of the added air, such as the increased role of C3 chemistry during the early stage of soot inception process. The addition of sufficient air into ethylene, however, changes soot particle temperatures and the understanding of soot formation characteristics becomes complicated. Measured soot particle temperatures also showed that there is no significant temperature effect for the synergistic effect of ethylene/propane mixture on soot formation.

• 한국해양공학회지
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• 제24권4호
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• pp.78-85
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• 2010

This study investigates reducing characteristics for the spreading of dredged soil and the diffusion of contaminant by silt protector curtain through three dimensional numerical experiment. The numerical medel is modified by combining the sediment transport characteristics for cohesive sediment into the previously developed model. Several numerical experiments have been given in order to investigate the reducing effect of silt protector using two dimensional numerical channel model under various parameters such as upstream flow velocity, depth of silt curtain and the position of dumped materials. Through the evaluation of several simulation results, we knew that the careful design has to be given in the determination of depth and position of silt protector.

• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1125-1134
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• 2017

In this paper, we present a new multilevel in space and energy diffusion (MSED) method for solving multigroup diffusion eigenvalue problems. The MSED method can be described as a PI scheme with three additional features: (1) a grey (one-group) diffusion equation used to efficiently converge the fission source and eigenvalue, (2) a space-dependent Wielandt shift technique used to reduce the number of PIs required, and (3) a multigrid-in-space linear solver for the linear solves required by each PI step. In MSED, the convergence of the solution of the multigroup diffusion eigenvalue problem is accelerated by performing work on lower-order equations with only one group and/or coarser spatial grids. Results from several Fourier analyses and a one-dimensional test code are provided to verify the efficiency of the MSED method and to justify the incorporation of the grey diffusion equation and the multigrid linear solver. These results highlight the potential efficiency of the MSED method as a solver for multidimensional multigroup diffusion eigenvalue problems, and they serve as a proof of principle for future work. Our ultimate goal is to implement the MSED method as an efficient solver for the two-dimensional/three-dimensional coarse mesh finite difference diffusion system in the Michigan parallel characteristics transport code. The work in this paper represents a necessary step towards that goal.

• 대한기계학회논문집
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• 제18권5호
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• pp.1253-1263
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• 1994

The experimental study is carried out to identify the combustion generated noise mechanism in free turbulent jet diffusion flames. Axial mean fluctuating velocities in cold and reacting flow fields were measured using hot-wire anemometer and LDv.The overall sound pressure level and their spectral distribution in far field with and without combustion were also measured in an anechoic chamber. The axial mean velocity is 10-25% faster and turbulent intensities are about 10 to 15% smaller near active reacting zone than those in nonreacting flow fields. And sound pressure level is about 10-20% higher in reacting flow fields. It is also shown that the spectra of the combustion noise has lower frequency characteristics over a broadband spectrum. These results indicate that the combustion noise characteristics in jet diffusion flames are dominated by energy containing large scale eddies and the combusting flow field itself. Scaling laws correlating the gas velocity and heat of combustion show that the acoustic power of the combustion noise is linearly proportional to the 3.8th power of the mean axial velocity rather than 8th power in nonreacting flow fields, and the SPL increases linearly with logarithmic 1/2th power of the heat of combustion.

• 한국IT서비스학회:학술대회논문집
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• 한국IT서비스학회 2008년도 추계학술대회
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• pp.127-130
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• 2008

Recently, a wide variety of research on the knowledge-based industries, which are considered a key area of social science research, has been conducted. In this light, this study examines a case of knowledge diffusion taken from the IT service field. The IT service industry has been considered difficult to diffuse due to its unique technological regimes and sophisticated market demand. In particular, the established public service systems have limited markets and encompass national characteristics, thereby making their international diffusion difficult. However, despite these limitations, the automated customs system ASYCUDA has been distributed successfully and is now operating in about 100 countries, making the case very unusual. Using various industrial innovation models, and an analysis of lead markets, with regard to ASYCUDA, this research examines patterns of technological learning activities by actors, characteristics of the lead markets, and paths of technology transfer. The findings indicate that when active technology providers attempt to streamline and standardize the technology to make it suitable for the characteristics of the initial technology application areas(lead markets), this helps to diffuse the technology to passive recipients and the surrounding nations. The findings also confirm that south-south cooperation in the acquired technologies was of considerable help in sharing knowledge among the passive technology recipients, and that the active technology providers' programmed, well-organized technology assistance was a key driving force behind technology transfer and diffusion between the surrounding nations.

• 인터넷정보학회논문지
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• 제11권5호
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• pp.37-58
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• 2010

본 논문은 IPTV 서비스의 수용과 확산을 위한 바람직한 정부의 정책 프레임워크를 분석하여 제시하고 있다. 지금까지 대부분의 연구들은 소비자 측면에서 개인적인 IPTV 서비스 수용과 확산에 국한되어져 있었기 때문에 조직관리적인 측면에서의 분석이 미흡한 실정이다. IPTV 서비스가 활성화되기 위해서는 다양한 정부의 지원정책 등이 필요하기 때문에, 본 연구에서는 개인 상황에서의 혁신 속성 이론과 조직 상황에서의 실행 프로세스 이론을 적용하였다. 즉 개인의 혁신성이 높은 경우에는 혁신의 속성들이 IPTV 서비스 수용에 더 큰 영향을 미치며, 혁신 관리 측면에서는 정책적 기대가 높은 상황에서 IPTV 관리 속성들이 수용에 더 큰 영향을 미칠 것으로 판단하였다. 본 연구의 결과 개인의 혁신성이 높을수록, 그리고 이와 함께 정부 정책에 대한 기대가 클수록 혁신의 속성 및 IPTV 관리 속성 모두가 IPTV 수용의도에 미치는 영향력이 높아지기 때문에, 정부 정책은 개인의 혁신성을 자극하면서 정책기대를 높이는 방안이 바람직한 것으로 분석되었다.

• 전자공학회논문지D
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• 제35D권1호
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• pp.84-93
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• 1998

Planar graded index optical waveguides have been formed by Ag$^{+}$ ion exchange in the BK7 optical glass. The experimental results of diffusion and modal characteristics of Ag$^{+}$-Na$^{+}$ exchanged BK7 glass waveguides are presented. Measurements of the mode indices have been measured. We found the relations between the process and device parameters such as the diffusion depth and the square root of the diffusion time, diffusion coefficient and diffusion temperature, and diffusion ion concentration and surface index change. A theoretical gaussian function refractive index profile matched best with the measured data for all the guided modes. The empirical relations between the process and the device parameters are derived and subsequently used to formulate a systematic procedure for fabricating singlemode and multimode waveguides.uides.

• 대한기계학회논문집B
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• 제23권11호
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• pp.1355-1362
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• 1999

An experimental study on a double-concentric diffusion flame(DDF) has been carried on in order to Investigate the characteristics of soot formation compared to a normal coflow diffusion flame(NDF). Laser extinction technique has been used for an ethylene($C_2H_4$) and air flame with various flow rates. Soot formation In the double-concentric diffusion flame was enhanced by the inner inverse diffusion flame due to the increase in flame temperature and also suppressed due to the nitrogen-dilution from the inner air. Soot concentration at the flame axis of DDF was higher than that of the NDF, mainly because of the increase of temperature by inner flame. However, the maximum soot volume fraction of DDF was lower than NDF at the outer side of the flame, mainly due to the effect of nitrogen-dilution from the inner air.

• 한국정보시스템학회지:정보시스템연구
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• 제10권1호
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• pp.97-126
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• 2001

Object-orientation has been proposed as a promising software process innovation to improve software productivity and quality. It has not been understood clearly, however, what factors influences the diffusion of object-oriented technology in organizations. A research model was formulated and hypotheses were generated based on the literature of information technology implementation and software process innovation. To test the research hypotheses, a questionnaire survey was conducted. The results based on 121 responses from Korean companies revealed that project characteristics, use of external experts, and number of development projects are significantly related to the diffusion of object-oriented analysis and design and object-oriented programming. Innovation champion is positively related to the diffusion of object-oriented analysis and design, whereas it is not related to the diffusion of object-oriented programming language. Only project complexity was significantly related to the diffusion of visual programming language. On the other hand, organizational size was not significantly related to any object-oriented technology in this study.

• 한국자기학회지
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• 제15권2호
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• pp.133-136
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• 2005

In the case of contacts between semiconductor and metal in semiconductor devices, they tend to be unstable because of thermal budget. To prevent these problems we deposited W-C-N diffusion barrier for preventing the interdiffusion between metal and semiconductor. The thickness of the barrier is $1,000{\AA}$ and the pressure is 3 mTorr during the deposition. In this work we coated LSMO (CMR material) on W-C-N diffusion barrier and then we studied the interface effects between LSMO layer and W-C-N diffusion barrier. We got results that the magnetic characteristics of LSMO thin film are still maintained after annealing at $800^{\circ}C$ for 3 hr because W-C-N thin diffusion barrier was prevented the diffusion of oxygen between LSMO and Si substrate.