• Advances in materials Research
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• v.5 no.2
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• pp.67-80
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• 2016

The objective of the present work is to optimize process parameters namely, cutting speed, feed rate, and depth of cut in milling of AISI 304 stainless steel. In this work, experiments were carried out as per the Taguchi experimental design and an $L_{27}$ orthogonal array was used to study the influence of various combinations of process parameters on surface roughness (Ra) and material removal rate (MRR). As a dynamic approach, the multiple response optimization was carried out using grey relational analysis (GRA) and desirability function analysis (DFA) for simultaneous evaluation. These two methods are considered in optimization, as both are multiple criteria evaluation and not much complicated. The optimum process parameters found to be cutting speed at 63 m/min, feed rate at 600 mm/min, and depth of cut at 0.8 mm. Analysis of variance (ANOVA) was employed to classify the significant parameters affecting the responses. The results indicate that depth of cut is the most significant parameter affecting multiple response characteristics of GFRP composites followed by feed rate and cutting speed. The experimental results for the optimal setting show that there is considerable improvement in the process.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.322-331
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• 2009

In clinical SPECT, FWHM provides quality information of the images obtained under different observing conditions. Therefore, the purpose of this study was to determine the optimum cut off level with comparison of FWHM according to cut off levels in each filter - Band limited, Sheep-Logan, Hanning, Hamming, Low pass cosine, Parazen and Butterworth filter in a SPECT camera. I recorded images along the X, Y, Z-axis with 99mTcO4 point source and measured FWHM with profile curves. In conclusion, all filters showed the longest figures of FWHM with cut off level 0.4, which has the worst image resolution. The images with cut off level 0.7 showed best image resolution. The shortest average of FWHM in MS2 was $11.07\pm0.07mm$ using the Butterworth filter, in MS3 it was $8.44\pm0.19mm$ through using the Hanning filter.

• The Korean Journal of Applied Statistics
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• v.27 no.3
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• pp.501-512
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• 2014

Modified cut-off sampling is widely used for highly skewed data. A serious drawback of modified cut-off sampling is the difficulty of adjustment of non-response in take-all stratum. Therefore, solutions of the problems of non-response in take-all stratum have been studied in various ways such as substitute of samples, imputation or re-weight method. In this paper, a new cut-off point based on minimizing MSE being used in exponential and power functions is suggested and it can be reduced the number of take-all stratum. We also investigate another cut-off point determination method with underlying distributions such as truncated log-normal and truncated gamma distributions. Finally we suggest the optimal cut-off point which has a minimum of take-all stratum size among suggested methods. Simulation studies are performed and Labor Survey data and simulated data are used for the case study.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.4
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• pp.64-73
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• 1999

This study was conducted to find out the effects of hydroseeding material and seed mixture on the revegetation of rock cut-slopes by PEC4 (Polymer-Ecology-Control) Hydroseeding Measures. PEC4 hydroseeding material was applied to four cut-slopes using hydroseeding measures from April to August, 1999, and the field survey was carried out by monthly. PEC4 material consisted of bark compost and organic soil amendments. This material has high content of organic matter and high level of water holding capacity. PEC4 hydroseeding material shows low level of soil hardness, so it gives to good condition for seed germinating and plant growing in early stage. PEC4 material attached at rock cut-slopes by two types of adhesive agent was not eroded by rainfall. The plant coverage and number of plant species were affected by mixing ratio of seeds and seeding timing. From the viewpoint of plant establishment, the optimal hydroseeding timing of mixed seeds for plant growth seems to be in May. Most of the plant seeds were germinated well and they covered rock cut-slopes so quickly and effectively. Plant importance value of Silene armeria and Platycodon grandiflorum. were higher than any other seeded-native species in the competition between native species and exotic species, so they have enough possibility to be used for slope revegetation works. Thus it leads to conclusion that the revegetation method used in this experiment was a very effective method for plant establishment on rock cut-slopes.

• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.164-171
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• 2013

In urban planning, road facility is used not only for the transportation purpose but also for the utility line space purpose such as electrical, gas, tele communication, heating, water, sewer, and so on. However, since these utilities are built by many different groups, it becomes very difficult to communicate each other. Delay in one party can cause another party's schedule delay but they don't commuicate often. Also, some delay in utility work can cause frequent pavement cut. And, this will impact on construction cost, schedule delay, low quality, user complain and cost. This study developed spatiotemporal decision model to prevent prequent utility cut for mega project such as new urban development project. In addition, this study developed utility cut management system to manage utility cut schedule under pavement. Finally, developed system was applied to new urban development project and verified there effectiveness.

• The Journal of Pediatrics of Korean Medicine
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• v.24 no.2
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• pp.99-111
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• 2010

Objectives The objectives of this study were to evaluate the correlations between the indices of obesity and percentage body fat by bioelectrical impedance analysis(BIA). Also, this study was designed to define the cut off values of percentage body fat by BIA which would represent BMI and degree of obesity in order to detect overweight and obesity in preschool children. Methods The height and weight of 683 children aged four to six years old were measured. Also, percentages of body fat were measured by BIA. Results There were high correlations between the boy's body fat percentages and degree of obesity(r=790). Also, there were high correlations between the girl's body fatpercentages and BMI(r=778). The cut off values of body fat percentage, which would correspond to those of BMI percentiles, were calculated by ROC curve analysis. To classify as an overweight, the correspondent cut off values of body fat percentage were 19.55% in boys and 22.35% in girls. For obesity, the cut off values were 28.80% in boys and 27.60% in girls. The cut off values of body fat percentage, which would correspond to degree of obesity were calculated by ROC curve analysis. To classify as an overweight, the correspondent cut off values of body fat percentage were 19.75% in boys and 22.35% in girls. For obesity, the cut off values were 29.05% in boys and 28.75% in girls. Conclusions According to the BMI criteria by the Korean pediatrics society in 2007, the most appropriate cut off values of body fat percentage in for four to six years old children were follows; for boys, 19.55% considered as overweight, and 28.80% as obese while for girls, 22.35% considered as overweight and 27.60% as obese. According to suggested degree of obesity criteria, the most appropriate cut off values of body fat percentage in for four to six old children were were follows; For boys, 19.75% was considered as overweight, and 29.05% as obesity. For girls, 22.35% was considered as overweight, and 28.75% as obese.

• Horticultural Science & Technology
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• v.33 no.3
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• pp.364-374
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• 2015

This study investigated quality changes in fresh-cut burdocks treated with hot water and anti-browning agents. The combined treatment using both heat treatment and anti-browning agents delayed the browning of burdocks, especially for those dipped in hot water and a solution of green tea extract plus NaCl. This treatment reduced the respiration rate and inhibited the growth of microorganisms more than heat treatment alone. The organoleptic quality of burdocks treated with the combined method proved to be the best according to sensory evaluation. Hence, this combined treatment using heat and anti-browning agents can enhance overall quality of processed fresh-cut root vegetables by browning inhibition and shelf-life extension.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1100-1105
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• 2007

In the gas supply duct, the gas leakage caused by the impact of the construct equipment is serious problem. The identification of the impact position is an important issue and an engineering work. For the basic research of this problem, the principle studies for the acoustic wave propagation in a gas duct are proceeded in this paper. This principal work is based on the identification of the cut-off frequency associated with major modes of the gas duct theoretically and experimentally. The cut-off frequency is confirmed by STFT and cross-correlation function is used to identify the leakage position.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.8
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• pp.797-804
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• 2008

In the gas supply pipe, the gas leakage caused by the impact of the construct equipment is serious problem. The identification of the impact position is an important issue and an engineering work. For the basic research of this problem, the principle studies for the acoustic wave propagation in a gas pipe are proceeded in this paper. This principal work is based on the identification of the cut-off frequency associated with major modes of the gas pipe theoretically and experimentally The cut-off frequency is confirmed by STFT and cross-correlation function is used to identify the leakage position.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.29-34
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• 2012

This paper reports some experimental results in high speed rigid tapping of magnesium alloy(AZ91D). M3 spiral tap and high speed spindle tapping center of gantry type were used in experiments and thrust forces were measured. The experimental results indicate that the thrust forces are proportional to the spindle speed and depth of cut. The thrust forces increase as the depth of cut increases. M3 Tapping was achieved at the spindle speed of 10,000rpm, depth of cut of 1.5D and total stroke of 32mm.