• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.4
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• pp.173-179
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• 2013

Even though a rough diamond shape is irregular and rugged, it is easy to be processed to make gem, shaped facets (table, crown, pavilion and girdle) were precisely treated because they influence on the evaluation of diamond grading. Those specifications suitable for the standard round brilliant cut diamond polishing were investigated and in 95 % statistical confidence interval, standard deviation, mean and acceptable tolerance were examined. According to these variables (size, angle, depth, and thickness) distribution, the frequency analysis of ratings and proportions were compared with each other. The correlation between each variables and the evidence of influence represented in proportion were determined by the regression analysis applying LSM (Least Square Method). In this research, it was recognized that table sizes of the diamond jewels and pavilion depth (in %) influence the rating decision and in particular, the depth of pavilion acting as the main factor of proportions, also plays an important role in optical phenomena.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.807-813
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• 1986

The orthogonal cutting method of the nodular graphite cast iron in the lathe turning, whose matrix were formulated under two kinds of annealing conditions, has been experimentally studied and the results investigated. The various characteristics of machinabilities of the nodular cast iron, depending upon its matrix, have been obtained from the results as follows. (1) As depth of cut increases, the cutting ratio and the shear angles tend to slightly increase, and as the containing quantity of ferrite matrix increases, they slightly decrease. (2) As depth of cut increases, the cutting force increases in an approximate straight line, and as the containing quantity of ferrite matrix increases, they decreases and the decreasing rate is about 20-30%. (3) As the containing quantity of ferrite matrix increases, the friction force acting on the tool face decreases and the decreasing rate is about 34-40% in case of the lower depth of cut, but in case of the higher depth of cut the decreasing rate is very small. (4) Both shearing force and vertical force show a lineal increases, and according as ferrite matrix increases there is a decrease by 25% in shearing force and a 12-25% decrease in vertical force. (5) Shearing speed and chip flow speed keep almost a constant value irrespective of matrix.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.4
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• pp.84-92
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• 1987

To investigate the influence of the cutting pressure on the laser cutting quality, an expermental facility was constructed which can measure the cutting pressure distribution for various cutting conditions. Flow visualization was performed using the Schlieren photography and the pressure acting on the workpiece surface was measured, corresponding to the important process variables such as the kind of assist gas, nozzle pressure, distance between the nozzle exit and the workpiece surface, and the presence of the secondary nozzle. The cutting pressure acting on the workpiece was largely influenced by the nozzle pressure and nozzle-workpiece distance. The secondary nozzle which is used to raise the effective working pressure had its obvious role only when the angle between it and the main nozzle was small and when the distance between the nozzle exit and the workpiece surface was large.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1166-1175
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• 1993

The objective of this study is to measure contra-retractive adhesion and lift resistance acting on the rim section of a circular wheel for analyses of their effects on the dynamic load. A circular iron wheel was used for experiments. A part of the wheel rim was cut off, and transducers which can measure normal and tangential forces were installed in this section. Experiments were conducted on a laboratory soil bin which was filled with clayey soil under wet and dry conditions. The mechanism of generating contra -retractive adhesion on a circular wheel were analyzed by the experiments and motion analyses of the wheel. Effects of lift resistance on dynamic load were analyzed by measured forces under wet soil conditions in comparison in comparison with those under dry conditions. The showed that a part of the lift resistance were transferred to the dynamic load. These results may become basic data and ideas for analyses of tractor dynamic under wet soil conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1286-1293
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• 2010

The ground anchor used in domestic area, which resists by adhesion between anchor body and the ground to the external force, seems not to be adequate for soft ground and urban area where the boundary between structures is close because the ground is disturbed and lost its strength during boring. In order to overcome such a shortcoming an expanded anchor system has been developed. The ground expansion is accomplished by means of Pulse Discharge Technology. In this technology, a high voltage of electricity is stored and discharged in milliseconds which induces high pressure acting on the ground. By making a couple of bulbs, a passive resistance as well as shaft resistance are mobilized, and therefore a higher pullout resistance comparing existing ground anchors is developed.In this study, a couple of full scale tests were conducted in order to figure out how much the resistance of an expanded anchor increases comparing to the straight. As a result, it was found that a remarkable increase in ultimate pullout capacity is observed for the soft ground and as the number of bulb increases. In addtion, as a result of applying to a cut slope reinforcement, it appeared that the length of fixed zone of anchor can be reduced effectively.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.772-785
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• 2021

Container ships has a transverse section in the form of an open profile, making it very sensitive to torsion phenomena. To minimize this effect, a structure known as a torsion box exists, which is subject to high stresses influenced by the fatigue phenomenon and the existence of cut-outs, for the passage of the longitudinal stiffeners, acting as stress concentrators. The aim of this study is to propose a two-stage design methodology to aid designers in satisfying the structural requirements and contribute with to a better understanding of the considered structure. The transverse webs of a torsional box structure are examined by comparing different cut-out geometries from numerical models with different regular load conditions to obtain the variables of the fatigue safety factor through linear regression models. The most appropriate geometry of the torsion box is established in terms of minimum weight, from nonlinear multivariable optimization models.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.23-33
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• 2015

The earth pressure acting on underground structure was measured by application of the instrumentation system in the subway construction site constructed by the method of cut-and-cover tunnel. The measured earth pressure was compared with the earth pressure obtained from the existed theoretical equation, and the actual earth pressure diagram acting on the underground structure was investigated. As a result of investigation, the vertical earth pressure is mainly affected by the embankment height, and the lateral earth pressure is significantly affected by whether the existence of earth retaining structures or not. The measured vertical earth pressure is very similar to the theoretical earth pressure proposed by Bierbaumer. The measured lateral earth pressure is closed to the active earth pressure proposed by Rankine rather than the earth pressure at rest. The coefficient of earth pressure in soil deposit layer is about 0.35, and the coefficient in soft rock deposit layer is about 0.21. For design and construction the underground structures, therefore, it is reasonable estimation that the lateral earth pressure acting on structures installed in soil deposit layers is an average value between active earth pressure and earth pressure at rest. In rock deposit layers, the lateral earth pressure acting on structure is an active earth pressure only.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.2123-2130
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• 2000

Radial immersion ratio is an important factor to determine the threshold in face milling and should be estimated in process for automatic force regulation. In this paper, presented is a method of on-line estimation of the radial immersion ratio using cutting force. When a tooth finishes sweeping, sudden drop of cutting forces occurs. This force drop is equal to the cutting force that acts on a single tooth at the swept angle of cut and can be obtained from cutting force signal in feed and cross-feed direction. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the swept angle of cut is a function of the swept angle of cut and the ratio of radial to tangential cutting force. In the research, it is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial to tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions. Using the measured cutting force and predetermined ratio, the radial immersion ratio is estimated. Various experiments show that the radial immersion ratio and instantaneous ratio of the radial to tangential direction cutting force can be estimated very well by the proposed method.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.241-243
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• 1996

This papar presents an analysing method of radial force densities acting on each stator tooth of an induction motor with skewed slots. Two-dimensional finite element method is used for electromagnetic Held analysis of an induction motor, and skew effects are considered by coupling several disks cut by planes perpendicular to the shaft. Radial force densities as a source of vibration are calculated along the surface elements of each stator tooth and its time harmonics are examined by discrete Fourier decomposition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.614-623
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• 2005

This study aims to perform the characteristic evaluation of surface grinding for the STD11 material with experimental and analytic techniques based on the response surface model. The grinding force acting on the workpiece and the ground surface roughness were measured according to the change of grain size, table speed and depth of cut. The effect of spark-out on the grinding force and the surface roughness was also characterized. The frictional coefficient between workpiece and grinding wheel could be determined by the analysis of spark-out effect. From the experimental data, the second-order response surface models were developed to predict the grinding force and the surface roughness. Validation of the developed model was examined.