• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.27-35
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• 2001

For the purpose of healing the degradation part, $CO_2$ laser beam was irradiated with different irradiation condition (porer, diameter, velocity and beam type) to find out optimum irradiation condition. The test series of hardness, residual stress measurement, and fatigue were carried out after the irradiation. Experimental results show that micro-hardness values on the surface of the irradiated specimens m approximately 2.5 times higher than those of un-irradiated ones. Fatigue tests show that the fatigue life was improved by the compressive residual stress after laser beam irradiation. However, some specimens with different conditions show the shorter fatigue life. It means that laser beam irradiation with optimum irradiation condition and optimum absorb energy, Q can improve the fatigue strength.

• Korean Journal of Veterinary Service
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• v.25 no.3
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• pp.221-227
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• 2002

This study was carried out to confirm analytical method of residual macrolides in livestock products by LC/MS. 1. Macrolides were analyzed by LC/MS on XTerra C$\sub$18/ column with 0.1% TFA(trifluoroacetic acid)-methanol in a gradient mode as mobile phase, and that were identified by positive chemical ionization with selective ion monitoring at 50～1000 mass range. 2. Residual macrolides were extracted from tissue with acetonitrile, and the extract is purified with a Sep-pak C$\sub$18/ cartridge, and elute macrolides with 0.1M methanolic ammonium acetate. 3. The procedure confirms the presence of each macrolide at 50$\mu\textrm{g}$/kg in spiked sample.

• Korean journal of food and cookery science
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• v.15 no.4
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• pp.382-387
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• 1999

This study was conducted to investigate the changes of mineral contents in radish leaves, soybean sprout and chwi namul by cooking method(boiling, steaming, sauting) and cooking time(1, 3, 5 min.). The residual rate of minerals(such as Calcium, Sodium, Potassium, Iron and Magnesium) in radish leaves, soybean sprout and chwi namul by 1 minute sauting was the range of 83.2 to 99.1%. It was shown that sauting was desirable method for all three vegetables. The residual rate by the cooking method was sauting, steaming, boiling, in that order, but boiling in radish leaves and chwi namul were more desirable method than steaming for Calcium use. At the cooking method and cooking time, Potassium content in soybean sprout was reduced remarkably in 5 minutes boiling. Boiling of radish leaves and soybean sprout showed that Sodium was reduced remarkably after 5 minutes of boiling, 54.4% for radish leaves and 19.9% for soybean sprout, respectively.

• Current Optics and Photonics
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• v.5 no.6
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• pp.627-640
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• 2021

In a free-space coherent optical communication system, wavefront distortion is frequently beyond the correction range of the adaptive-optics system after the laser has propagated through the atmospheric turbulence. A method of residual wavefront correction is proposed, to improve the quality of coherent optical communication in free space. The relationship between the wavefront phase expanded by Zernike polynomials and the mixing efficiency is derived analytically. The influence of Zernike-polynomial distortion on the bit-error rate (BER) of a phase-modulation system is analyzed. From the theoretical analysis, the BER of the system changes periodically, due to the periodic extension of wavefront distortion. Experimental results show that the BER after correction is reduced from 10^-1 to 10^-4; however, when the closed-loop control algorithm with residual correction is used, the experimental results show that the BER is reduced from 10^-1 to 10^-7.

• Journal of Welding and Joining
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• v.17 no.1
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• pp.88-96
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• 1999

The effects of root gap on welding residual stress and deformation are dealt with the multi-pass weldment with three kinds(0, 6, 30mm) of root gap by F.E.M common code, and then compared with experiment data. In this analysis, an 100% ramp heat input model was used to avoid numerical convergence problem due to an instantaneous increase in temperature near the fusion zone, and the effect of a moving arc in a two dimensional plane was also included. During the analysis, a small time increment was applied in a period with instantaneous temperature fluctuation while a large time increment was used in the rest period. The residual stress is distributed as symmetric types and maximum value is also equivalent when the weldment with 0mm and 6mm root gap is welded. In the case of 30mm root gap welding, the distribution of the residual stress extends over a wide range as asymmetric types due to the built-up weld, and most of the residual stress is biased in the side of a built-up weld part. In case of 0mm gap welding and 6mm gap welding, a little angular distortion occurs, but the level of deformation is small. When the weldment with 30mm root gap is welded, the angular deformation of the asymmetric types, however, occurs larger than the other specimens. The experimental and the analytic results show good coincidence and indicate that the welding residual stress and deformation distribution of 30 mm root gap specimen may be asymmetric and the amplitude is larger than those of root gap specimen under standard.

• Korean Journal of Community Nutrition
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• v.3 no.3
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• pp.454-465
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• 1998

This study was to investigate the recognition level of food contamination with residual pesticides and hazardous heavy metals from 365 male and female adults in Taejon area using questionnaires. Among the recognizing level of residual pesticides in overall foods, 69.1% were 'serious', 25.6% were 'average' and 5.3% were 'not serious'. Over 94.7% of the subjects recognized residual pesticides pollution infoods. for hazardous heavy metals in food, 47.8% responsed as 'serious', 40.5% as 'average' and 11.8 as ' not serious' . Over 88.3% of the subjects recognized contaminated pesticides seriously in fruits, 72.1% in vegetables and 51.7% in cereals, whereas 55.7% of the subjects recognized hazardous heavy metal contamination seriously in fruits, 53.4% in vegetables, 40.8% in fishes and shellfishes and 35.0% in seaweeds. The subjects recognized residual pesticides contamination more seriously in overall foods, cereal, potatoes and starches, bean, vegetables and fruits, whereas hazardous heavy metal contamination was recognized more seriously in fishes and shellfishes, and seaweeds food groups. Comparisons were shown based on individuial's occupation. Farmer, forester, iner and fisher showed the lowest recognizing level of food contamination in most food groups. The mean score of the dietary effect by mass media's information on food contamination from residual pesticides and hazardous heavy metals were 3.51±0.96 out of 5 points. By Duncan's multiple range test, sex, age, marriage, food cost per month, concerns about health and nutrition knowledge showed significant differences in the mean effect score at p<0.05. According to a pesticides contamination in several food groups were affected by food cost per month, mass media's information on food contamination, health status, and concerns about health, But a recognition level of hazardous heavy metals in food were affected by income and, food cost per month mass media's information on food contamination, health status, concern about health and nutrition knowledge. People who need to take extreme precautions of food contamination were in order of producers, government officials, homemakers, the consumer's association and consumers.

• Journal of Chest Surgery
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• v.28 no.3
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• pp.237-246
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• 1995

Between March 1989 and December 1994, one-stage repair was performed for correction of the intracardiac malformations associated with aortic coarctation in 34 patients or interrupted aortic arch in 8 patients via median sternotomy. There were 26 male and 16 female patients, and their body weight ranged from 1.8 to 8 kg [mean weight, 4.0 1.4 kg . The age at the operation ranged from 7 days to 18 months [mean age, 3.1 $\pm$ 3.8 months . The repair of aortic coarctation or interrupted aortic arch was performed using extended end-to-end anastomosis in most of the patients [86%, 36/42 , and six patients underwent ductal tissue excision and patch aortoplasty. Intracardiac defects were corrected concomitantly through the right atrium unless the anatomy dictated otherwise. Obstructive outlet septum was resected whenever necessary. There were seven early deaths [16.8 % , and three late deaths with a mean follow-up period of 25 months [range from 1 to 65 months . Three patients were reoperated upon residual subaortic stenosis, stenosis at the RPA origin, and subacute bacterial endocarditis respectively. None showed any significant residual or anastomotic stenosis postoperatively. One stage repair of the aortic coarctation and interrupted aortic arch associated with intracardiac defect leaves no native coarctation shelf tissue or residual hypoplasia in the repaired segment, has low incidence of recurrent or residual stenosis, minimizes reoperation and incisions, and manages arch hypoplasia easily. We concluded that surgical results of one-stage repair for the intracardiac malformation associated with aortic coarctation or interrupted aortic arch are reasonable.

• Journal of Ocean Engineering and Technology
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• v.16 no.3
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• pp.54-58
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• 2002

This study investigates a relationship between fracture mechanics parameters (Stress Intensity Factor Range: ΔK, Maximum Stress Intensity Factor; Kmax) and X-ray parameters (residual stress:$\sigma$r half-value breadth: B) for SG365 steel at elevated temperature up to 30$0^{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to the direction of crack length was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase at low ΔK region, to reach a maximum value at a certain value of Kmax or ΔK and then to decrease. Residual stress was independent of stress ratio by arrangement of ΔK and half value breadth were independent of the arrangement of Kmax. The equation of $\sigma$r-ΔK was established by the experimental data. therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

• Journal of the Korean Society of Safety
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• v.17 no.1
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• pp.33-38
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• 2002

SS41 material is welded automatically and is investigated some effects of the welding residual stress on the growth and propagation of fatigue crack, so as to study the fatigue behaviour in the welding residual stress field. The summarized results are as follows; 1) In case of the load amplitude is constant, as the stress ration is changing to 0.1, 0.33 and 0.5 the propagation life is constant but the initiation life decreases. And than, when maximum load or minimum load is constant, s the stress ration increases the initiation life and propagation life. 2) It was shown that the fatigue crack propagation ratio da/dn was almost constant regardless of the stress ratio change at constant load amplitude and that the larger stress ratio, the slower was the fatigue crack propagation ratio. 3) The opening ratio U is influenced by $K_{max}$ but it isn't only the function of $K_{max}$ because data range is very large. 4) The fatigue life of the specimens on tensile compressive residual stress field was decreased and increased respectably more than that of the base metal.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.256-261
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• 2007

The purpose of this study is to investigate the effect of shot peening on the fatigue strength and fatigue life of two kinds of aluminum alloys. The fatigue strength behavior of aluminum alloys were estimated by the stress ratio and shot velocities. The fatigue life and strength increased with increasing the test shot velocity. However, at the shot velocity range between 50m/s and 70m/s, the compressive residual stress phenomena were observed in test conditions of different shot velocity. The optimal shot velocity is acquired by considering the peak values of the compressive residual stress, dislocations, brittle striation, slip, and fisheye on the fracture surface of test specimen. It was observed from the SEM observation on the deformed specimen that the brittle striation, fisheye were showed in the intergranular fracture structure boundaries at the this velocities. Therefore, fatigue strength and fatigue life would be considered that shot velocity has close relationship with the compressive residual stress.