• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1281-1288
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• 2009

Variation of dynamic characteristics of a low pressure turbine blade with crack length is studied in this paper via both experiments and finite element model. Since most of the turbine blades used in domestic power plants are imported from abroad, it is necessary to understand their dynamic behavior in advance. When experimentally obtained natural frequencies and mode shapes are compared with those from FEM results, they are close to each other in their magnitude. Then, it is more feasible to use finite element model for analyzing the dynamic characteristics of a blade under various operation conditions (rotation speed, temperature, etc) as well as with a crack in the blade.

• Journal of the Korean Home Economics Association
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• v.36 no.6
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• pp.13-26
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• 1998

This study investigated first, socio-economic, residential characteristics, and values for future life among low-income family wives. Second, the relationship of these characteristics to the wives' stress was examined. The subjects were 249 mothers of urban low-income families whose children attended one of 20 daycare centers located in poor residential areas. The instruments included Social Network Scale, Home Stress Scale, and Occupation Stress Scale. Data were analyzed by means, standard deviations, frequencies, paired t-tests, and the stepwise multiple regressions. We found that a majority of the mothers and their husbands had high school educational status and simple labor or sales/service work status. They lived in rental houses or apartments. Their families of origin were a major source of emotional supports. Insufficient income for non-employed wives, long work hours and lack of free time for employed wives were a major stress. Levels of the wives' home-related job-related stress were negatively related to their own and their hudsbands' work status.

• MALSORI
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• no.61
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• pp.31-48
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• 2007

This study investigated the roles of name agreement and word frequency in the English-Korean word translation task. Using the low-frequency homonyms with low name agreement as stimuli, Experiment 1 revealed that the name agreement of materials is a determinant which could modulate times to translate English words into Korean equivalents. On the contrary, Experiment 2 showed that the name agreement of materials does not play a decisive role in the translation task, using the low-frequency homonyms having high name agreement as stimuli. In Experiment 3, we identified that the frequency effects observed from previous two experiments are indeed brought about during the lexical access. Our findings suggest that the word frequencies of materials have a strong influence on English-Korean word translation times, and homonyms are represented independently each other in the lexeme level.

• Korea-Australia Rheology Journal
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• v.15 no.2
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• pp.63-73
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• 2003

An experimental technique was developed to determine the strain-rate in a tensile specimen. Then one can calculate the transient isothermal elongational viscosity. Both shear and elongational viscosities were measured to study the effect of shear and elongational fields on the flow properties. The comparison between these viscosities shows that the onset of rapid viscosity growth as crystallization solidification proceeds occurs at about the same value of time at very small deformation rates (0.0028 and 0.0047 $s^{-1}$). The comparison of these measured viscosities as functions of shear and elongational Hencky strains also reveals that the onset of rapid viscosity growths starts at critical Hencky strain values. The behaviour of steady shear viscosity as function of temperature sweep was also explored at three different low shear rates. Finally, the influence of changing oscillatory frequencies and strain rates was also investigated.

• Current Optics and Photonics
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• v.7 no.2
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• pp.176-182
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• 2023

Optical coherence tomography (OCT) is being developed to guide various ophthalmic surgical procedures. However, the high cost of the intraoperative OCT system limits its availability mostly to the largest hospitals and healthcare systems. In this paper, we present a design and evaluation of a low-cost intraoperative common-path free-hand scanning OCT system. The lensed fiber imaging probe is designed and fabricated for intraocular use and the free-hand scanning algorithm that could operate at a low scanning speed was developed. Since the system operates at low frequencies, the cost of the overall system is significantly lower than other commercial intraoperative OCT systems. The assembled system is characterized and shows that it meets the design specifications. The handheld OCT imaging probe is tested on multilayer tape phantom and ex-vivo porcine eyes. The results show that the system could be used as an intraoperative intraocular OCT imaging device.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.632-640
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• 2007

The low force estimation method of skeletal muscle was proposed by using ICA(independent component analysis) and neuro-transmission model. An EMG decomposition is the procedure by which the signal is classified into its constituent MUAP(motor unit action potential). The force index of electromyography was due to the generation of MUAP. To estimate low force, current analysis technique, such as RMS(root mean square) and MAV(mean absolute value), have not been shown to provide direct measures of the number and timing of motoneurons firing or their firing frequencies, but are used due to lack of other options. In this paper, the method based on ICA and chemical signal transmission mechanism from neuron to muscle was proposed. The force generation model consists of two linear, first-order low pass filters separated by a static non-linearity. The model takes a modulated IPI(inter pulse interval) as input and produces isometric force as output. Both the step and random train were applied to the neuro-transmission model. As a results, the ICA has shown remarkable enhancement by finding a hidden MAUP from the original superimposed EMG signal and estimating accurate IPI. And the proposed estimation technique shows good agreements with the low force measured comparing with RMS and MAV method to the input patterns.

• Korean Journal of Environmental Agriculture
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• v.2 no.2
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• pp.83-89
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• 1983

To obtain basic information for the safe use of pesticides, the aquatic environment of 5 major rivers was surveyed in April and August 1982 for organochlorine and organophosphorus pesticide residues. Regardless of sampling times and sites, pesticide residue levels were very low. Of the organophosphorus pesticides surveyed, only IBP and diazinon were detected in water samples while fenthion, fenitrothion, chlorpyriphos, chlorpyriphos-methyl, chlorfenvinphos, phenthoate, and edifenphos were not detected in any water samples. Residue levels and detection frequencies of IBP or diazinon were much higher in water samples collected in August than those collected in April. Detection frequencies of organochlorine pesticides, on the other hand, were high, but their actual residue levels were very low. BHC was detected nearly in all water samples while aldrin was not found in any samples. Detection frequencies of heptachlor, endosulfan, and o.p`-DDT were considerably high but dieldrin and p.p`-DDT were detected in a few water samples and their residue levels were also very low.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.3
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• pp.373-384
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• 1999

The purposes of this study were 1) to test the differences between two groups who have high and low purchase of apparel in low-price retailing concerning consumers' beliefs and attitude toward low-prce retailing 2) to identify differences between these two groups in type of information search and use of information sources and 3) to investigate differences between department store and low-price retailing in consumers' satisfaction toward products and purchase frequencies of apparel items and differences between two groups in demographic variables. The data were collected via a self-administeered questionnaire from 474 femail adults in Seoul Korea and analyzed by factor analysis t-test and paired t-test. The results of this study were as follows : First based on a series of t-test and paired t-test. the results showed that those who had a high purchase of apparel in low-price retailing had significantly higher belief scores on all of the five store attributes and a more favorable attitude toward low-price retailing than did those who had low purchase. Second those who had high purchase of apparel in low-price retailing had significantly higher scores on ongoing and prepurchase information search and on use of mass media information and interpersonal information source than did those who had low purchase. Third in case of high purchase consumers of apparel in low-price retailing there were not found significant differences between department store and low-price retailing there were not found significant differences between department store and low-price retailing in purchase frequency on man's and women's casual wear of department stores than low-price retailing. However low purchase consumers of apparel in low-price retailing revealed significantly higher purchase frequency on all of seven apparel items of department stores than low-price retailing. Finally there were significant differences between two groups in demographic variables. The papers discussed theoretical implications as well as manageral implications.

• Journal of IKEEE
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• v.18 no.1
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• pp.37-44
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• 2014

In this paper we present an LDO based on an error amplifier. The designed error amplifier has a gain of 89.93dB at low frequencies. This amplifier's Bandwidth is 50.8MHz and its phase margin is $59.2^{\circ}C$. Also we proposed a BGR. This BGR has a low output variation with temperature and its PSRR at 1 KHz is -71.5dB. For a temperature variation from $-40^{\circ}C$ to $125^{\circ}C$ we have just 9.4mV variation in 3.3V LDO output. Also it is stable for a wide range of output load currents [0-200mA] and a $1{\mu}F$ output capacitor and its line regulation and especially load regulation is very small comparing other papers. The PSRR of proposed LDO is -61.16dB at 1 KHz. Also we designed it for several output voltages by using a ladder of resistors, transmission gates and a decoder. Low power consumption is the other superiority of this LDO which is just 1.55mW in full load. The circuit was designed in $0.35{\mu}m$ CMOS process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.606-611
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• 2000

It has been noted that the low frequency absorption coefficient of a porous sample placed in a standing wave tube is affected by the nature of the sample's edge constraint. The edge constraint has the effect of stiffening the solid phase of the sample, which itself can be strongly coupled to the material's fluid phase, and hence the incident sound field, by viscous means at low frequencies. In recent work it has also been shown that such a circumferential constraint causes the low frequency transmission loss of a layer of fibrous material to approach a finite low frequency limit that is proportional to the flow resistance of the layer and which is substantially higher than that of an unconstrained sample of the same material. However, it was also found that the benefit of the circumferential edge constraint was reduced in a transitional frequency range by a shearing resonance of the sample. Here it will be shown that the effect of that resonance can be mitigated or eliminated by adding additional axial and radial constraints running through the sample. It will also be shown that the constraint effect can be modeled closely by using a finite element procedure based on the Biot poroelastic theory. Implications for low frequency barrier design are also discussed.