• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.487-490
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• 2002

In this paper, we report a novel way to evaluate the anticlinic interlayer coupling coefficient U between smectic layers of an antiferroelectric liquid crystal, by utilizing a small field-induced perturbation of the molecular orientation. U was found to exhibit an unusual "S-shaped" dependence on temperature, with values ranging between $0.4{\times}10^4$ and $0.4{\times}10^{-1}$ erg $cm^{-3}$ over a 10$^{\circ}C$ temperature range below smectic A-smectic $C_A$ phase transition temperature. The results are good agreement with estimates for U based upon the threshold field for the onset of solitary waves, and provide strong supporting the low-field regime for the single Fourier component model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.723-730
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• 2003

The CN(carbon nitrogen) nanofibers were formed by HIP(high isostatic pressure) process. From the field emission measurement, CN nanofibers shows an excellent characteristics of emitter, better than CNTs and carbon nanofibers. The structures obtained can be divided into three groups : bamboo-like fibers, corrugated structures and bead necklace-like fib res. Emission properties of CN nanofibers were investigated for spacing, between anode and cathode, variation. Turn-on fields was 1.4 v/$\mu\textrm{m}$. The time reliability and light emission test were carried out for about 100 hours. We suggest that CN nanofibers can be possibly applied to the high brightness flat lamp because of low turn-on field and time reliability

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.353-356
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• 1996

Early this year the construction of new high voltage power lines have been forced to stop due to the demonstration of residents in Kwa-chun. According to mutual agreement between the residents and Korea Electric Power Corporation, electromagnetic field(EMF) from present power lines was measured and EMF after completion of new power lines was estimated. The results show that EMF near power lines Is relatively low, and EMFnear electric substation is quite high due to the short distance between the power lines and ground. For 4 conduction 345kV line, magnetic field decreases to 3mG at the distance of 50m from the power line.

• KIEAE Journal
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• v.11 no.6
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• pp.53-62
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• 2011

This study aimed at suggesting improvement of lighting environment of the coffee house using study place. To this end, a series of field investigation was conducted in four possible target coffee houses around university. The field measurement included measurement of general illuminance and tabletop illuminance, observing illumination condition, and status of artificial lighting. Also, on-site questionnaire survey was administrated to 80 users of field measurement targets about using characteristics of coffee house and user's subjective response on light environment. The results are summarized as follows: (1) According to questionnaire survey, most of users checked 'learning (study and reading)' in 'purpose of coffee house using', and 'slightly dark' was checked most in each subjective response (brightness on general space and on tabletop at daytime/night); (2) as results of measurements on general illuminance and on tabletop illuminance during daytime, only one coffee house was suitable for standard; (3) as results of measurements on illuminance during night, all target coffee houses were not met the standard; (4) as results of uniformity ratios, almost uniformities of general illuminance were not met the standard except one case. The common problems of lighting environment of coffee house were analyzed as lack of daylight illumination e.g. having low amount of sunshine from skylight, un-uniformity of insolation by floor plan and absence of window blind, and un-uniformity of artificial luminous intensity e.g. lack of the number or brightness of artificial lighting, using the indirect lighting, using only local lighting, and non-uniform arrangement of artificial lighting.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.685-691
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• 2011

The aim of this study is to point out the uniqueness of Doppler optical coherence tomography (DOCT) for use in a probe station for (in vivo) visualization of microscale flow and structure and to maximize the effectiveness of DOCT by overcoming its limitations. Conventional DOCT produces images of only one of the velocity components that is parallel to the incident light. In this study, a multi-angle DOCT to quantify a velocity vector field is proposed; this is an extension from a velocity scalar field to a vector field. Quantifying an instantaneous three-dimensional velocity field in a pulsating flow is another challenge because of its limited frame rate. The in-vivo pulsating blood flow is measured by using an electrocardiogram-gated multi-angle DOCT in a hamster cheek pouch model. It is shown that the aliasing problem caused by a relatively low frame rate is resolved by using this method of measurement.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.11
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• pp.3003-3013
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• 1995

The characteristics of the flow field in the tangentially fired furnace are presented. Experiments are conducted in the simplified cold type isothermal flow model. In the measurement of flow field, a hot wire anemometer is used. The hot wire was calibrated by lookup table method. The mean velocity field and turbulence characteristics are showed with changing the nozzle angle. In the center of the model, the low speed, unstable flow region is formed. The size and position of these regions are varied with changing the nozzle angle. It can be used as fundamental data in the design of the large furnace. From the experimental results, various turbulent characteristics of swirling flow field is obtained. And the entrainment mechanism of the jet flow field is described from the distribution of the skewness and the flatness. It can be used the raw data of approximate calculation and turbulent modelling.

• Water Engineering Research
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• v.3 no.2
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• pp.135-142
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• 2002

This study investigates the effects of sediment on the flow characteristics such as velocity distribution, friction velocity, turbulent intensities, Reynolds stress, etc. Particle tracking velocimetry (PTY) is used to measure the vertical flow field. Results show that flow over the high bed-load concentration region has larger values of mean velocity and friction velocity and smaller values of turbulence intensities, compared to those for flow over the low bed-load concentration region.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.04a
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• pp.172-173
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• 2002

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.431-437
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• 2000

The aim of the work described in this paper is to develope a pavement method for farm road. To this ends, a series of material test are conducted on in-situ soil which was mixed additives-coarse aggregate, polypropylene fiber, excellent soil compound etc. With the laboratory test results, in-situ pavement test was conducted during two years. The serious problem of the pavement is not appeared up to this time. And the measurement of field data is continued presently. The majority merits of this pavement method is low cost and using environmental materials.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.127-127
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• 2017