• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1234-1243
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• 1990

Double coaxial are jets(annular and coaxial air jets) between which propane gas is fed was selected to study the structure of diffusion flames in turbulent shear flow. Schlieren and direct photographs are taken to visualize the flame structure. Mean and fluctuating temperatures and ion currents were measured to investigate the macroscopic and the instantaneous flame structure. The objective of this study is to understand the interaction between combustion and mixing process especially in the transition region of turbulent shear flow. The investigation reported in this paper focuses on the macroscopic and the instantaneous structures of three flames obtained. The increased mixing effect resulting from increase of Reynolds number of central air jet makes the flame bluish and short. When the velocity of surrounding air stream is higher than that of central air jet, the instantaneous flame structure is composed of coherent structure. It is considered that the flame structure of transitional region of mixing layer depends on the structure of mixing layer of non-reacting conditions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.40-46
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• 2007

In this paper, the effect of a Doppler Spread caused by a mobile station (MS) is analyzed for transparent mobile multi-hop relays (MMR) systems based on orthogonal frequency division multiplexing (OFDM). The exact expression of interchannel interference (ICI) power and the upper bounds of ICI power are derived for OFDM systems with cooperative MMR or non-coopeartive throughput enhancement (TE) MMR. Also, the exact signal-to-interference ratio (SIR) and its lower bound as well as ICI power and its upper bound, derived in this paper, are evaluated by computer simulation with the OFDM parameter set used for mobile WiMax (WiBro) systems.

• Nuclear Engineering and Technology
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• v.19 no.2
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• pp.99-106
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• 1987

Comparison study on the radiological effects by radionuclides from hypothetical 1,000MWe coal-fired power station and nuclear power plant is made. This paper describes the radiological effects only for gaseous effluents released in normal operation. Source terms for coal-fired Power station are quoted from foreign data and those for nuclear power plant are calculated for reference power plant. Gaussian plume model is used to assess atmospheric dispersion of radioactive effluents based on one year meteorological data of Kori site and individual doses are calculated at the maximum X/Q point. Doses from nuclear power plant are slightly more than those from coal-fred power plant. In the case of coal-fired power plant, doses by ingestion of contaminated vegetation are 73.5% of total doses.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.890-892
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• 2014

최근 스마트기기가 널리 보급되고 소셜네트워크 서비스가 확산되면서, 스마트 기기 및 소셜미디어를 활용함으로서 학습에서 상호작용을 극대화한 교육환경으로 스마트러닝이 크게 부각되고 있다. 그리고 스마트러닝 콘텐츠 및 환경의 확산으로 PC 위주에서 스마트폰 등으로 이러닝 콘텐츠의 사용환경이 확장됨에 따라 콘텐츠 저작의 경제성과 효율성 등을 고려하게 되었으며, 하나의 콘텐츠를 다양한 환경에서 활용 가능하도록 하고 있다. 그러나 기존 PC기반의 콘텐츠를 스마트기기에 적용함에 있어 여러 가지 문제가 발생하는데 이 문제들을 해결하는 방안으로 먼저 콘텐츠에 대한 표준화가 중요한 요소로 작용한다. 따라서 본 논문에서는 전자책 표준화를 활용한 효율적인 스마트러닝 기법을 제시하고자 한다.

• Korean Journal of Materials Research
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• v.9 no.10
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• pp.1025-1031
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• 1999

Alloys of TiAl with six different compositions. i. e., Ti-(42, 44)Al-2Nb-4V. Ti-(42, 44)Al-4Nb-2V and Ti -(42, 44)Al-4Nb-2Cr, were manufactured by arc-melting. and their oxidation behavior was studied. Both isothermal and cyclic oxidation tests were performed at 700, 800 and $900^{\circ}C$ in air for 50hr. The oxidation resistance increased in the order of Ti-(42, 44)Al-2Nb-4V, Ti-(42, 44)Al-4Nb-ZV and Ti-(42, 44)Al-4Nb-2Cr. It was found that V was a deleterious element, while Cr was a beneficial element in terms of oxidation resistance. During oxidation, a simultaneous interdiffusion was observed. All the constituent elements in the base alloys diffused outward. whereas oxygen from the atmosphere diffused inward, to form triple oxide layers composed of an outermost $\textrm{TiO}_2$ layer. upper ($\textrm{TiO}_2+\textrm{Al}_2\textrm{O}_3$) mixed layer, and lower $\textrm{TiO}_2$-rich layer.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.275-280
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• 2010

Recently, This paper suggests that LED-ID technique applying positioning method for LED light. also, Authors in this paper has launched this investigation earnestly. However, there are various interferences such as MPI(Multi Path Interference) by reflected waves of the surface and interfere factors by their correlation properties of the ID in LED-ID wireless channel. Therefore, in this paper, we propose a novel OOK(On-Off Keying)-CDMA(Code Division Multiple Access) system using unipolar ZCD(Zero Correlation Duration) spreading code and verify the availability of the proposed system via the evaluation performance simulation.

• Korean Journal of Optics and Photonics
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• v.20 no.3
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• pp.182-188
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• 2009

The surface plasmon resonance ellipsometer (SPRE), using a multiple air injection system with an extraction of air system, has been proposed and developed to minimize measurement error of signals due to diffusion of reagent into running buffer. Since the diffusion of reagent into running buffer affects the refractive index of the running buffer by changing the concentration, characteristics of binding between various bio-molecules don't appear clearly in measurement results. The diffusion between running buffer and reagent can be blocked by using an air bubble injection system. An extraction of air system is used to remove the noise signal due to unnecessary air bubbles flowing in a channel. Reliability of measurement results has been improved by using the valve system.

• Journal of The Korean Association For Science Education
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• v.20 no.2
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• pp.329-343
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• 2000

The purpose of this study is to develop the middle school science curriculum to enhance creative problem-solving abilities. The reconstructed curriculum consisted of three big components, that is, scientific knowledge, process skills, and creative thinking skills. Five themes have been selected to incorporate with four areas of the middle school science curriculum, namely, physics, chemistry, biology, earth science. The five themes are structure, change, interaction, energy, and stability. Based upon these five themes, the individual or separated scientific knowledges of learners can be put into the unified knowledges. The process skills were observing, measuring, classifying, communicating, inferring, predicting, variable differentiating controling, data gathering analysis, establishing hypotheses, experiment design, and experimenting. Creative thinking skills include divergent and critical thinking. The finally developed curriculum is presented in the form of matrix.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.279-285
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• 1993

It is important to understand the interrelationship between adsorption, equilibrium and mass transport in efficient design and operation of the granular activated carbon(GAC) adsorption systems. In this study, the micro-diameter-depth adsorption system(MIDDAS) technique was developed to estimate equilibrium and mass transport parameters, which were utilized to simulate adsorption and mass transport phenomena dynamically and mathematically. The homogeneous surface diffusion model(HSDM) utilizing the estimated equilibrium and mass transport parameters including the film transfer coefficients and surface diffusivities from the MIDDAS technique, successfully predicted competitive adsorption, desorption and chromatographic displacement effects. In the binary solute system of p-chlorophenol(PCP) and p-nitrophenol(PNP), PCP was displaced by PNP and the HSDM could predict successfully. While the HSDM described the desorption breakthrough curves for PCP, PNP and PTS well when complete reversible adsorption was assumed, the desorption breakthrough curves for DBS could be predicted after subsequent incorporation of the degree of irreversibility into the model simulations.

• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1090-1098
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• 1998

$RuO_2$ thin films were deposited on Si and Ru/Si substrates by rf magnetron reactive sputtering and annealed in oxygen atmosphere(1atm) to investigate their thermal stability and diffusion barrier property. $RuO_2$ thin films were thermally stable up to 700\ulcorner for 10min. in oxygen atmosphere and showed excellent barrier property against the interdiffusion of silicon and oxygen. After annealing at $750^{\circ}C$ , however, volatilization to higher oxide occurred at the surface and inside of $RuO_2$ thin film and diffusion barrier property was also deteriorated. When annealed at $800^{\circ}C$, $RuO_2$thin film showed a different microstructure from that of $RuO_2$ thin film annealed at 75$0^{\circ}C$. It is likely that surface defect structure of $RuO_2$, $RuO_3$, and excess oxygen had an influence on the mode of volatilization with increasing annealing temperature.