• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1141-1148
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• 2008

One of the methods to increase the efficiency of an engine is to expand pressures obtained from combustions equal to the pressure of atmosphere as much as possible and then convert thermal energy into mechanical energy also as much as possible. In this research, the Diesel cycle was thermodynamically interpreted to evaluate the possibility of high efficiency by converting Diesel engines to the Atkinson cycle, and general cycle features were analyzed after comparing these two cycles. In the case of fuel air the Diesel-Atkinson cycle considering intake and exhaust similar to real cycles, the value of thermal efficiency and average effective pressure increased, though their values were smaller than those of standard air amount cycle, when expansion compression ratio increased. When normal Diesel engines of which compression stroke and expansion stroke are all the same, was converted to the Atkinson cycle by changing the time of intake value close, combustion pressure reduced due to reduced expansion compression ratio and intake air amount due to decreased effective cycle volume.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.54-62
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• 1999

In this paper, we investigated the signal-to-noise ratio improvement in a differential detector, which is a function of the optical noise coupling ratio and the differential gain ratio. A differential detector consists of two photodiodes and a differential amplifier. The differential detector reduced the noise component and improved the signal-to-noise ratio by about 20 dB when the differential gain ratio equals to the optical noise coupling ratio. The differential detector is very effective in removing the environmental optical noise or interference from an adjacent optical channel. This method is also effective when the noise wavelength is similar to the signal.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.89-99
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• 2015

In this research, 1,032 data of precise safety inspection from 2004 to 2013 are gathered and constructed for finding effective safety inspection systems. Items are extracted from constructed data and factors for typology are decided with statistical method such as principle component analysis and cluster analysis. For factor decision, we extruded independent characteristics such as morphological and geographical characteristic, and deleted items which can be expressed by combination of independent characteristics. Four factors such as total storage, watershed ratio, levee length ratio, and spillway length ratio are extracted in this process. In cluster analysis, levee length ratio is excluded because it is not separated as cluster. Finally nine types of agricultural reservoir are extruded by total storage, watershed ratio, and spillway length ratio with frequency analysis.

• Journal of the Korean Ceramic Society
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• v.35 no.6
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• pp.603-609
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• 1998

The composites of insulating polymer filled with conducting carbon-fiber were fabricated by molding press method. To understand the fiber aspect-ratio dependence of electrical conductivity the aspect ratio was varied from 4 to 10 The percolation thresholds of transition from the insulator to the conductor de-creased as the fiber aspect ratio increased. The percolation threshold of fiber-segregated composite in this study was smaller than that of fiber-random composite shown in other study. When the electrical con-ductivity curves were fitted by general effective medium equation morphological variable(t) decreased as the fiber aspect-ratio increased.

• International Journal of Highway Engineering
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• v.3 no.1 s.7
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• pp.185-197
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• 2001

This paper dealt with modification of effective crack length model (ECM) by adding Poisson's ratio term to evaluate fracture toughness of asphalt concrete which varies its material property by temperature. The original ECM model was developed for solid materials, such as cement concrete, and Poisson's ratio of materials was not considered. However, since asphalt concrete is sensitive to temperature variation and changes its Poisson's ratio by temperature, it should be taken into consideration to know exact fracture property under various temperatures. Four binders, including 3 polymer-modified asphalt (PMA) binders, were used to make a dense-grade asphalt mixture and 3-point bending test was peformed on notched beam at low temperatures, from -5oC to 35oC. Elastic modulus, flexural strength and fracture toughness were obtained from the test. The results showed that, since Poisson's ratio was considered, the more accurate test values could be obtained using modified ECM equation than original ECM. PMA mixture showed higher stiffness and fracture toughness than normal asphalt mixture under very low temperatures.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.8
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• pp.1230-1237
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• 2018

Objective: The present study was undertaken to determine an optimal balance between the amount of physically effective neutral detergent fiber (peNDF) to metabolizable glucose (MG) on rumen fermentation, blood metabolites and growth performance of 8 to 10-month-old heifers. Methods: A total of 15 healthy Holstein heifers weighing an average of 256 kg (8 month of age) were randomly assigned to three groups of five. Treatment diets consisted of the following three $peNDF_{8.0}/MG$ levels: 1.46 (Treatment A), 1.74 (Treatment B), and 2.08 (Treatment C). Results: The results showed that the ratio of $peNDF_{8.0}/MG$ affected rumen fermentation, blood metabolites and growth performance of heifers. The average daily gain of heifers tended to decrease as the ratio of $peNDF_{8.0}/MG$ increased (p = 0.07). The concentrations of blood urea nitrogen, triglyceride, and cholesterol increased significantly (p<0.05), while the high-density lipoprotein concentration decreased (p<0.05). After feeding 2 h and 4 h, insulin concentration in Treatment A was greater than Treatment C (p<0.05). Propionate concentration had decreasing trend (p = 0.07); acetate to propionate ratio and non-glucogenic to glucogenic volatile fatty acid (NGR) increased significantly (p<0.05). In addition, the digestibility of dry matter, crude protein, neutral detergent fiber, and acid detergent fiber decreased significantly (p<0.05). Conclusion: The present investigation indicated that dietary $peNDF_{8.0}/MG$ ratio can affect the growth and development, blood metabolites, rumen fermentation and apparent digestibility of heifers, and the optimal dietary $peNDF_{8.0}/MG$ ratio for 8 to 10-month-old heifers in the present study was 1.46.

• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.131-139
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• 1992

The understanding and appllication of fatigue crack propagation mechanism in variable amplitude loading is very important for life prediction of the air travel structures. Particularly, the retardation and arrest behavior of fatigue crack propagation by single tension overloading is essential to the understanding and appllication of fatigue crack propagation mechanism in variable amplitude loading. Numerous studies of the retardation behavior have been performed, however investigations of the arrest behavior have not been enough yet. As for the arrest behavior, Willenborg had reported that the overload shut-off ratio $[R_{so}=(K_{OL})/K_{max})_{crack arrest}]$ had been the material constant, but recently several investigators have reported that the overload shut-off ratio depends upon the stress ratio. In this study, authors have investigated the effect of stress ratio on the threshold overload shut-off ratio to generate arrest of fatigue crack growth in high tensile aluminum alloy 7075-T735 which have used in material for air travel structures, It has been $-0.4\leqqR\leqq0.4$ till now, the region of stress ratio investigated. The threshold overload shut-off ratio has decreased as stress ratio has increased in overall region of -$-0.4\leqqR\leqq0.4$ and the linearity has been seen in this material. Moreover, the experimental equation between $R_{so}$ and R has been made; The relation has been $R_{so}=-R+2.6$.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.16 no.1
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• pp.141-153
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• 2003

Introduction : The causes of sudden sensorineural hearing loss have not been detemined with precision until recently, but viral infections and vascular insufficiencies, such as vascular spasm, occlusion of sludging of erythrocytes were considered as major factors. The treatment has not been determined with precision until recently. It is similar to dizziness(眩暈). sudden dcafncss(暴聾) and congestion-fire deafness(痰火聾) in Oriental Medicine. It is very rare that someone has sudden hearing loss and visit Oriental Medicine Clinic right that time. But we expect if they take a Oriental treatment on thc right time. more effective for their symptom. Subjects : Following conclusions were reached by measuring results of oricntal medical treatments for 40 patients who visited the clinic between January of 2000 and December of 2002, and received treatments continuously for more than 1 months of time. Methods : Among the selected 40 patients. 30 patients belong to Group Ⅰ, which consisted of patients who had already visited a general hospital prior to visiting this clinic, achieved no recovery at all from sudden deafness despite going through more than 5 days of hospitalized treatments of steroidal medications. Group Ⅱ was consisted of 10 patients of sudden deafness who did not experience any steroidal treatments from other hospital prior to the oriental medical treatment. Results and conclusion : According to differentiation of syndrome. among 30 patients of the Group Ⅰ. 21 were categorized as excess syndrome patients and remaining 9 as deficiency syndrome paticnts. Among 10 patients of For Group Ⅱ, 5 were excess syndrome patients and remaining 5 were deficiency syndrome patients. Among Group Ⅰ, recovery ratio of excess syndrome patients was 47.7$\%$ and deficiency syndrome patients was 44.4$\%$ adding up recovery ratio of the group to be 46.1$\%$. Among Group Ⅱ, recovery ratio of excess syndrome patients was 80$\%$ and deficiency syndrome patients was 100$\%$ adding up recovery ratio of the group to be 90$\%$. Oriental medical treatments are generally more effective(90$\%$ recovery ratio) for Sudden Deafness than steroidal treatments. Oriental medical treatments are almost equally effective for both excess syndrome patients and deficiency syndrome patients. However, steroidal treatments for excess syndrom patients(45$\%$ recovery ratio) is much less effective than deficiency syndrome patients(73$\%$ recovery ratio). This indicates that steroidal treatments should be applied selectively to deficiency syndrome patients if applied at all. Even for patients with sudden deafness which hospitalized steroidal treatments did not result in any recovery at all, oriental medical treatments were able to achieve 46.1$\%$ recovery ratio.

• Journal of Radiation Protection and Research
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• v.47 no.2
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• pp.77-85
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• 2022

Background: After the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, a model was developed to estimate the external exposure doses for residents who were expected to return to their homes after evacuation orders were lifted. However, the model's accuracy and uncertainties in parameters used to estimate external doses have not been evaluated. Materials and Methods: The model estimates effective doses based on the integrated ambient dose equivalent (H^*(10)) and life patterns, considering a dose reduction factor to estimate the indoor H^*(10) and a conversion factor from H^*(10) to the effective dose. Because personal dose equivalent (H_p(10)) has been reported to agree well with the effective dose after the FDNPS accident, this study validates the model's accuracy by comparing the estimated effective doses with H_p(10). The H_p(10) and life pattern data were collected for 36 adult participants who lived or worked near the FDNPS in 2019. Results and Discussion: The estimated effective doses correlated significantly with H_p(10); however, the estimated effective doses were lower than H_p(10) for indoor sites. A comparison with the measured indoor H^*(10) showed that the estimated indoor H^*(10) was not underestimated. However, the H_p(10) to H^*(10) ratio indoors, which corresponds to the practical conversion factor from H^*(10) to the effective dose, was significantly larger than the same ratio outdoors, meaning that the conversion factor of 0.6 is not appropriate for indoors due to the changes in irradiation geometry and gamma spectra. This could have led to a lower effective dose than H_p(10). Conclusion: The estimated effective doses correlated significantly with H_p(10), demonstrating the model's applicability for effective dose estimation. However, the lower value of the effective dose indoors could be because the conversion factor did not reflect the actual environment.

• Journal of the Korean Geotechnical Society
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• v.27 no.9
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• pp.13-24
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• 2011

The renowned Terzaghi's one-dimensional consolidation theory is not applicable to quantification of time-rate settlement for highly deformable soft clays such as dredged soil deposits. To deal with this special condition, a non-linear finite strain consolidation theory should be adopted to predict the settlement of dredged soil deposits including self-weight and surcharge-induced consolidation. It is of importance to determine the zero effective stress void ratio ($e_{00}$), which is the void ratio at effective stress equal to zero, and the relationships of void ratio-effective stress and of void ratio-hydraulic conductivity for characterizing non-linear finite strain consolidation behavior for deformable dredged soil deposits. The zero effective stress void ratio means a transitional status from sedimentation to self-weight consolidation of dredged soils. In this paper, laboratory procedures and equipments are introduced to measure such key parameters in the non-linear finite strain consolidation analysis. In addition, the non-linear finite strain consolidation parameters of the Incheon clay and kaolinite are evaluated with the aid of the proposed methods in this paper, which will be used as input parameters for the non-linear finite strain consolidation analyses being performed in the companion paper.