• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.3
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• pp.20-26
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• 2010

In ultrashort-pulse reflectometry (USPR), a chirped waveform transformed from the USPR source impulse signal via waveguide makes it possible to employ millimeter-wave mixers for the frequency up-conversion process. Consequently, the frequency bandwidth of the USPR system is sufficiently wide to cover a large portion of the electron density profile of the plasma. Some physical aspects of the chirped waveform, such as maximum amplitude and length, are critical factors to determine the performance of the system. In this paper, the propagation of the USPR impulse signal through a rectangular waveguide is numerically studied to derive the chirped waveform using the impulse response of the waveguide. The results of numerical computation show that the chirped waveform significantly depends on the waveguide cutoff frequency as well as the waveguide length.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.12
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• pp.1947-1956
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• 2010

This study is to understand fashion product aesthetics by exploring the antecedents of aesthetic experiences and the influence of aesthetic experiences on impulse buying behavior. A total of 520 usable questionnaires were obtained through an internet survey. A structural equation model using a correlation matrix with maximum likelihood was estimated by using AMOS 18.0 to examine the relationships among aesthetic value, aesthetic acumen, affective experience, cognitive experience, and impulse buying behavior. The results showed that aesthetic value and acumen had a significant effect on the cognition of aesthetic experiences and that aesthetic experiences had a significant effect on impulse buying behavior. These results highlight the powerful motivational force behind fashion product aesthetics. The key implications for research and management are discussed further.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.491-492
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• 2008

This paper describes the series-gap characteristics of transmission line arrester with switching and lightning impulse flashover test. The transmission line arrester exhibited external gap because it is must not flashover with switching impulse on the other hand it is must flashover with lightning impulse. In accordance, minimum and maximum length of series-gap was determinated with these tests. As gap length is increased flashover voltage was increased in the range of 315.4 kV~496.3 kV and negative polarity exhibited a high voltage. As a result, It was thought tat the series-gap length of transmission line arrester exhibited in the range of 580 mm~1100 mm.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.30-34
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• 2012

A safety helmet is a personal protective equipment to protect the head from falling and flying objects. A safety helmet has the maximum delivered impact force as shock absorption performance, the lower delivered impact force the better performance, which was not a controlled variety during manufacturing safety helmet. Accordingly there were some difficulties in establishing the standard for improved performance as there was not a clear controllable impact force for improved performance. In this study the shock absorption performance was intended to be found as coefficient of restitution related to impulse. As a research method, a coefficient of restitution during the absorption of shock was calculated using the impulse transferred to pharynx utilizing the safety helmet shock absorption performance testing device based on the theory of momentum and impulse. The estimated impulsive force curve was derived assuming that shock was not absorbed using the measured data. The sample was selected as tested goods of ABS material for safety certification available mainly in the market. As a result of study, the maximum delivered impact force of safety helmet made by a domestic safety certified a company was 735 N, and its coefficient of restitution proved to be 0.64. The smaller coefficient of restitution is, the lower maximum delivered impact force and the higher shock absorption performance. The coefficient of restitution can be used as a performance index of safety helmet.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.294-299
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• 2004

An assessment of a novel laser-electric hybrid propulsion system was conducted, in which a laser-induced plasma was induced through laser beam irradiation onto a solid target and accelerated by electrical means instead of direct acceleration only by using a laser beam. A fundamental study of newly developed rectangular laser-assisted pulsed-plasma thruster (PPT) was conducted. On discharge characteristics and thrust performances with increased peak current compared to our previous study to increase effects of electromagnetic forces on plasma acceleration. Maximum peak current increased for our early study by increasing electromagnetic effects in a laser assisted PPT. At 8.65 J discharge energy, the maximum current reached about 8000 A. Plasma behaviors emitted from a thruster in various cases were observed with an ICCD camera. It was shown that the plasma behaviors were almost identical between low and high voltage cases in initial several hundred nanoseconds, however, plasma emission with longer duration was observed in higher voltage cases. Canted current sheet structures were also observed in the higher voltage cases using a larger capacitor. With a newly developed torsion-balance type thrust stand, thrust performances of laser assisted PPT could be estimated. The impulse bit and specific impulse linearly increased. On the other hand, coupling coefficient and the thrust efficiency did not increase linearly. The coupling coefficient decreased with energy showing maximum value (20.8 ？Nsec/J) at 0 J, or in a pure laser ablation cases. Thrust efficiency first decreased with energy from 0 to 1.4 J and then increased linearly with energy from 1.4 J to 8.6 J. At 8.65 J operation, impulse bit of 38.1 ？Nsec, specific impulse of 3791 sec, thrust efficiency of 8 %, and coupling coefficient of 4.3 ？Nsec/J were obtained.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3518-3523
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• 2007

An analysis program of specific impulse has been developed for a gas generator cycle rocket engine. The program has been verified by comparing the published performance data of the same cycle engine with RP-1 as fuel. A model for pressure drop of regenerative cooling and film cooling mass flow rate has been suggested to satisfy the necessary cooling condition with Jet-A1 as fuel. The engine mixture ratio is defined by the film cooling mass flow rate and the core mixture ratio. The optimal condition of the combustor pressure and engine mixture ratio has been found for maximum specific impulse.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2286-2288
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• 2005

This paper describes impulse grounding impedance and touch voltage when impulse current is injected to grounding systems for distribution concrete pole. Impulse grounding impedance is a significant factor in analyzing transient grounding impedance. The touch voltage is measured in four directions. The maximum touch voltage was 520V and the minimum touch voltage was 47.3V when the input current was 100A.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.1
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• pp.87-96
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• 2014

E-shopping is traditional method to purchase products in a modern society. Fashion products are one of the most popular product categories sold and impulsively bought online. This study examined the causal relationship of shopping value, positive emotion, urge to buy impulsively, and e-impulse buying in the context of shopping for apparel products. A self-administered questionnaire developed from the literature was administered in class to 501 female college students in Busan. AMOS 21.0 estimated the structural equation model of e-impulse buying using a correlation matrix with a maximum likelihood. The analysis of the data supported most of the predictions. The results suggested that consumer shopping values (hedonic shopping value and utilitarian shopping value) had a positive effect on positive emotion; in addition, positive emotion urge to buy impulsively directly affected the e-impulse buying of apparel products. In the structural model, e-impulse buying of consumers can be predicted by the attitudinal component (e.g., shopping values), emotional factors (e.g., enthusiastic or proud), and the urge to buy impulsively felt by young consumers. There are implications that both positive emotion and impulsive buying are important predictors for the e-impulse buying of apparel products by consumers. Moreover, the urge to buy impulsively was an important mediator to determine the e-impulse buying of apparel products. This study provides insight to retailers and researchers to understand the structural relationship of consumer characteristics and the e-impulse buying of apparel products.

• Korean Journal of Food Science and Technology
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• v.23 no.1
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• pp.37-43
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• 1991

The nerve impulse pattern of Chorda tympani(CT) of cat was tested with Monosodium glutamate(MSG) solutions as well as some basic taste substances applied on the tongue of cat. The effect of MSG applied in the tongue prior to the stimulation of other taste substances was also investigated. The response impulse frequency of CT of cat was changed by the kind and concentration of taste substances. The response to citric acid was the highest among the tested substances, NaCl, KCl and MSG showed similar responses. When different concentrations of MSG were applied on the tongue prior to other substances, the response to NaCl increased with the maximum response at the MSG concentration of 0.02 M. The response to sucrose tended to be reduced, but the response to citric acid was distinctly supressed by the previous MSG stimulation. These results were well consistent with the sensory evaluation on the effect of MSG to some basic taste substances. previously reported by the authors.

• Journal of Biosystems Engineering
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• v.33 no.4
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• pp.239-247
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• 2008

Firmness is very important factor to evaluate the freshness and ripeness among the various factors, in concerning about the melon quality. This study was carried out to develop the technique using impact signal to measure the melon firmness nondestructively. Results of analyzing impulse signals of melons having different firmness levels showed that the firmness of melon affected various impulse responses including amplitude, transmitted time, maximum peak frequency, firmness index 1 ($f^2m$), and firmness index 2 ($f^2m^{2/3}$). Impulse signal amplitude was the best indicator to predict the firmness of melon because of a strong corelation ($R^2\;=\;0.9071$). Firmness index 1, firmness index 2, maximum peak frequency, and normalized transmitted time were also possible indicators with acceptable correlation values.