• Journal of Korea Water Resources Association
• /
• v.42 no.8
• /
• pp.659-671
• /
• 2009

Fuzzy c-means clustering technique is applied to improve the accuracy of G/R ratio used for rainfall estimation by radar reflectivity. G/R ratio is computed by the ground rainfall records at AWS(Automatic Weather System) sites to the radar estimated rainfall from the reflectivity of Kwangduck Mt. radar station with 100km effective range. G/R ratio is calculated by two methods: the first one uses a single G/R ratio for the entire effective range and the other two different G/R ratio for two regions that is formed by clustering analysis, and absolute relative error and root mean squared error are employed for evaluating the accuracy of radar rainfall estimation from two G/R ratios. As a result, the radar rainfall estimated by two different G/R ratio from clustering analysis is more accurate than that by a single G/R ratio for the entire range.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.15 no.4
• /
• pp.17-27
• /
• 2013

This study has the purpose to examine the effects of stone massage therapy on abdominal obesity reduction. 10 sessions for 5 weeks two times a week of stone massage therapy were offered to 43 adult females who were 40s through 70s with 27% or more of body fat and the results were analyzed. The body composition like body fat mass, fat free mass, weight and skeletal muscular mass etc and the degrees of obesity like body fat ratio abdominal fat ratio were measured and analyzed before and after stone massage therapy. The results are as follows: First, the subjects were obese body type and stone massage therapy produced positive effects with body fat mass, fat free mass, weight and BMI value slightly less than before the therapy. Second, as the average values of body fat ratio and waist hip ratio of subject were significantly different statistically before and after the therapy, stone massage therapy was found to be effective in reducing abdominal obesity. Third, as for the change of waist hip ratio, the therapy was found to be effective in reducing waist hip ratio that 40s decreased insignificantly after the therapy, and 50s and 60s significantly at p<0.05 level respectively from 0.92 to 0.90 and from 0.93 to 0.92. In conclusion, the results of this study indicated that stone massage therapy has positive effects on abdominal obesity reduction, and can contribute to healthy life and well-being culture.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.6
• /
• pp.835-842
• /
• 2009

The present thesis carried out a research on a compression pressure's reduction phenomenon and its countermeasure according to the thermal efficiency improvement method by a Miller method in 4-cycle low speed diesel engine. In case of retardation of intake valve closing time in a engine, the theoretical heat efficiency shows a remarkably reducing trend when a compression ratio is not compensated. Accordingly, the thermal efficiency showed an increasing trend in case of compensating the compression ratio. Especially, it could be understood that the theoretical heat efficiency at near ABDC $100^{\circ}$ of intake valve closing time in case of compensation of the compression ratio was improved by around 25.1%, and the mean effective pressure was also increased by around 18.6%. Also, as the retardation of intake valve closing time increases, air quantity becomes insufficient due to a backflow phenomenon of intake air and thus thermal efficiency was decreased in a high load operation domain. The solving method of this problem is possible by supercharge. Therefore, in order to improve thermal efficiency by retardation of ntake valve closing time, the thermal efficiency improvement according to low compression is possible when there are a compensation device of a compression ratio and a supercharge device. This is a problem-solving method of low compression and high expansion cycle.

• Structural Engineering and Mechanics
• /
• v.70 no.4
• /
• pp.499-511
• /
• 2019

In this study, the axial compressive behavior of novel quadruple C-channel built-up cold-formed steel columns with different slenderness ratio was investigated, using the experimental and numerical analysis. The axial compressive capacity and failure modes of the columns were obtained and analyzed. The finite element models considering the geometry, material and contact nonlinearity were developed to simulate and analyze the structural behavior of the columns further. There was a great correlation between the numerical analyses and test results, which indicated that the finite element model was reasonable and accurate. Then influence of, slenderness ratio, flange width-to-thickness ratio and screw spacing on the mechanical behavior of the columns were studied, respectively. The tests and numerical results show that due to small slenderness ratio, the failure modes of the specimens are generally local buckling and distortional buckling. The axial compressive strength and stiffness of the quadruple C-channel built-up cold-formed steel columns decrease with the increase of maximum slenderness ratio. When the screw spacing is ranging from 150mm to 450mm, the axial compressive strength and stiffness of the quadruple C-channel built-up cold-formed steel columns change little. The axial compressive capacity of quadruple C-channel built-up cold-formed steel columns increases with the decrease of flange width-thickness ratio. A modified effective length factor is proposed to quantify the axial compressive capacity of the quadruple C-channel built-up cold-formed steel columns with U-shaped track in the ends.

• Smart Structures and Systems
• /
• v.29 no.3
• /
• pp.387-393
• /
• 2022

This paper presents the vibration analysis of cracked ceramic-reinforced aluminum composite beams by using a method based on changes in modal strain energy. The crack is considered to be straight. The effective properties of composite materials of the beams are estimated through Mori-Tanaka micromechanical model. Comparison study and numerical simulations with various parameters; ceramic volume fraction, reinforcement aspect ratio, ratio of the reinforcement Young's modulus to the matrix Young's modulus and ratio of the reinforcement density to the matrix density are taken into investigation. Results demonstrate the pronounced effects of these parameters on intact and cracked ceramic aluminum beams.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.37 no.5
• /
• pp.73-80
• /
• 1995

The uses of stage-storage curve function are diverse in irrigation reservoirs. The curve functions would be used to determine the optimal size of spillway length and the inundation area above full water level based on the flood routing in reservoirs. In addition, the curve function would he used to transform the stage to the storage for the reservoir water management, in which the storage is the supply water. Besides those, the curve is necessary for the planning of dredging, the estimation of the effective and the dead storage, the drought management by reservoir, etc. The curve function data, however, are almost unavailable for these purposes. According to the statistics, about 74% of the 2, 900 resevoirs which are maintained by Farm Land Improvement Association have no more effective data. Therefore, the simulation of the curve function could be better alternative. The curve functions were simulated derivating the regression equations based on the basin relief ratio and the effective depth. The results of the verification show the enough reliability of the application to generate the curve function in some reservoirs which do not have the surveyed stage-storage data. Also, even though the averaged curve function would be applicated without the basin relief ratio data, the result shows that the simulated curve is closer to the real one than the linear function by only the existing effective storage data.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.22 no.5
• /
• pp.403-410
• /
• 2009

In this paper, damping coefficients and effective masses of tuned liquid-type column dampers were quantitatively evaluated based on experimental results by using system identification technique. First, shaking table tests were performed for two types of tuned liquid-type column dampers. Then, the dynamic characteristics of dampers used in this study were experimentally grasped from harmonic wave excitation testing results of the dampers with various water level. Finally, damping ratios and effective masses of the dampers with varying water level were quantitatively evaluated from minimizing the errors between numerical and experimental results. It was confirmed from system identification results that damping ratio and effective mass are decreased as the water level of dampers is increased.

• Journal of the Korean Society of Costume
• /
• v.42
• /
• pp.223-230
• /
• 1999

Dressmaking which is defined as the process of changing two-dimensional cloth into three-dime-nsional clothes needs a lot of joining parts. Particularly sleeve needs a more curved surface than other joining parts owing to shape of the top of arms. Easing is used to control the fullness along the seam-line to create the fullness curved shape of the sleeves and it plays an important role in increasing three-dimensional constru-ction power. unfortunately sufficient data regarding effective easing conditions to increase three-dimensional construction power of sleeve are not available. Therefore the author tried to investigate the effective easing conditions to increase three-dimensional construction power of sleeve by cap height. Easing construction power of sleeve by cap height. Easing contraction made by different angles on the sleeve cap curve line previous work were examined and the effective easing conditions according to the variation of angles were determined. This study contains the following objectives. Firstly to obtain the easing contraction ratio in sleeve according to the above easing conditions. Secondly to investigate the three-dimensional construction power or sleeve by the factors of easing contraction. Thirdly to determine for each sleeve the effective easing conditions on the basis of the calcuative easing contraction ratio in the sleeve patterns by cap heights.

• Geomechanics and Engineering
• /
• v.11 no.6
• /
• pp.805-820
• /
• 2016

A fully coupled non-linear effective stress response finite difference (FD) model is built to survey the counter-intuitive recent findings on the reliance of pore water pressure ratio on foundation contact pressure. Two alternative design scenarios for a benchmark problem are explored and contrasted in the light of construction emission rates using the EFFC-DFI methodology. A strain-hardening effective stress plasticity model is adopted to simulate the dynamic loading. A combination of input motions, contact pressure, initial vertical total pressure and distance to foundation centreline are employed, as model variables, to further investigate the control of permanent and variable actions on the residual pore pressure ratio. The model is verified against the Ghosh and Madabhushi high acceleration field test database. The outputs of this work are aimed to improve the current computer-aided seismic foundation design that relies on ground's packing state and consistency. The results confirm that on seismic excitation of shallow foundations, the likelihood of effective stress loss is greater in deeper depths and across free field. For the benchmark problem, adopting a shallow foundation system instead of piled foundation benefitted in a 75% less emission rate, a marked proportion of which is owed to reduced materials and haulage carbon cost.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.8
• /
• pp.1100-1106
• /
• 2009

Recently, there are quite a lot of attention is drown on the researches related to of Miller method applied high expansion cycle. For this study, high expansion cycles are formed and analyzed with the base view point of thermodynamics, and the features of each factors are also investigated. As a result of analysis, the expansion-compression ratio is expected with a decrease of effective compression ratio as intake valve closing time retarded, however, the decrease of mean effective pressure and its output is accompanied with the counterflow of intake air. Accordingly, as the consequence of such failure, it is expected that an alternative is needed for the realization of high expansion cycles, and the improvement over thermal efficiency. To materialize such cycle, the control system to delay the closing time of intake valve was designed and VVT, the 3 S/B low speed diesel engine, is applied to evaluate the efficiency. The result of the trial shows that there was no significant errors.