• Journal of Advanced Marine Engineering and Technology
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• 제12권1호
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• pp.28-36
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• 1988

Since the oil shocks of 1970s, the quality of the fuel oil for marine diesel engines has become more degarded than ever. When the poorer quality fuel is burned, carbon residues of the fuel oil cause blockage of the fuel injection valve nozzle and troubles of fuel injection system. The mis-firing of engine occurs due to the decrease of fuel quantity injected, the decrease of compression pressure in the slow speed range, the increase of fuel leaked and the high ignition temperature of degraded fuel etc. This paper is to investigate theoretically the effects of mis-firing on the crankshaft axial vibration of diesel engine. The cylinder pressure in operation is calculated by the computer aided simulation of closed cycle for a large two-stroke diesel engine and also the exciting force of axial vibration and the resonance amplitudes are calculated. And then, the condition of normal state, misfiring and one-cylinder cut-off operation are analyzed. The results of calculations show good agreements with those of the actual measurements.

• 한국생산제조학회지
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• 제18권6호
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• pp.681-689
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• 2009

Disk grinding was often applied to deburring process in order to enhance the final product quality. Inherent chamfering capability of the flexible disk grinding process in the early stage was analyzed with respect to various process parameters including workpiece length, wheel speed, depth of cut and feed. Initial chamfered edge defined as arc zone was characterized with local radius of curvature. Averaged radius and arc zone ratio was well evaluated using neural network system. Additional neural network analysis adding workpiece length showed enhance performance in predicting arc zone ratio and curvature radius with reduced error rate. A process condition design parameter was estimated using remaining input and output parameters with the prediction error rate lower than 2.0% depending on the relevant input parameter combination and neural network structure composition.

• 한국생산제조학회지
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• 제19권3호
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• pp.381-387
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• 2010

This paper presents a study of the influence of fixed pressure in turning. The effect of roundness error and diameter deformation were studied with respect to the fixed pressure applied inside the cylindrical work piece made by boring tool in CNC lathe. The boring tool used in this study is a tungsten carbide coated. The material of workpiece is SM45C and the machining method is dry cutting. Cutting conditions as cutting speed, feed rate and depth of cut are constant. Finally, the change of fixed pressure had influence on the roundness error and diameter deformation.

• Journal of Plant Biology
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• 제18권1호
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• pp.1-10
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• 1975

Development of a model system for mode of action studies of $SO_2$ was attempted with a plant tissue. Leaf disks, 1.0cm diameter, cut from the lamina of lettuce leaves, were floated on the testing medium and placed in light or dark condition to investigate the discoloration pattern with various sources of $SO_2$. Discoloration of leaf disks tended to be more serious with higher concentrations of $SO_2$ and on exposure to the light. Leaf disks were more severely discolored at lower pH with constant SO2 concentration. These discoloration patterns were highly reproducible and similar in all sources of $SO_2$. Spectrophotometric evidence suggested that light-mediated discoloration of leaf disks in the presence of $SO_2$ might occur mainly through chlorophyll ${\alpha}$ degradation.

• 한국자동차공학회논문집
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• 제1권2호
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• pp.134-143
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• 1993

The trajectory planning for the manipulator installed on "the automatic pothole repair vehicle" is discussed and the final surface of the patched pot hole is simulated in this work. The relationship between the accumulation data of the mixture with and without the movement of the manipulator is identified to utilize the latter data for the calculation of the former one. Based on this relationship, the method to calculate the accumulation of the mixture when the manipulator changes the speed and the direction is also introduced. The trajectory is determined to make the final surface smooth under the condition that the pothole is cut to hexahedron before patching and only the spacing and the shifting of the manipulator is controllable. Final surface is simulated by the computer to prove the adequacy of the determined trajectory.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.1016-1019
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• 2005

In the cutting of plate steel, the quality of the cut surfaces is strongly dependent on the cutting condition such as cutting speed, plate thickness, power, kerf width and gas pressure etc. The cutting tests of Steel Automobile Press Hot were carried out using $CO_2$ Laser cutting machine. The kerf width and surface roughness of a section are examined at various cutting conditions. This paper deals with cutting characteristics of Steel Automobile Press Hot(SAPH400) using $CO_2$ Laser Cutting Machine.

• Advances in materials Research
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• 제7권2호
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• pp.137-148
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• 2018

The present paper is a contribution in characterising end milling process of AISI 52100 ball bearing steel through statistical analyses of variance (ANOVA). The latter has been performed to identify the effect of the cutting parameters on the machined surface roughness and the cutting tool life. Wear measurements have been carried on multilayer coated carbide inserts and the respective surface roughness has been recorded. Taguchi's technique has been adapted to conduct the design experiments in terms of orthogonal arrays according to the cutting parameters (cutting speed, feed rate and depth of cut), the type of coating (TiN, TiCN, TiAlN) and lubricating condition. Regression analyses have conducted to the development of simplified empirical models that can be effectively used to predict surface roughness and tool wear in the present milling process.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.831-837
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• 2005

In this study, a computer program to predict the behavior of laterally loaded single pile and pile groups was developed by using a beam-column analysis in which the soils are modeled as nonlinear springs by a family of p-y curves for subgrade modulus. The special attention was given to the lateral displacement of a single pile and pile groups due to the soil condition and the cap rigidity. The analysis considering group effect was carried out for $2\;{\times}\;2\;and\;3\;{\times}\;3$ pile groups with the pile spacing 3.0B, 4.0B and 5.0B. Based on the results obtained, it is found that the overall distributions of deflection, slope, moment, and shear force in a single pile give a reasonable results irrespective of cap connectivity conditions. It is also found that even though there are some deviations in deflection prediction compared with the observed ones, the prediction by present analysis simulates much better the general trend observed by the centrifuge tests than the numerical solution predicted by PIGLET.

• 한국기계가공학회지
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• 제7권2호
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• pp.23-30
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• 2008

As a basic machining process, turning is a widely used machining process in which a single-point cutting tool removes material from the surface of a rotating material. A common method of evaluating machining performance is to measure the surface roughness. In a turning operation, it is important to select cutting conditions for achieving high cutting performance. As a rule, cutting conditions can be classified into feed rate, depth of cut and insert radius. While cutting process even though cutting conditions are optimized, the average roughness can be deterioration due to wear of the cutting tool edge. In this study, the aim is to maintain the average roughness even though the cutting condition is irregularly changing within the predictable range due to the working environment. First, the surface roughness model influenced by cutting conditions is constructed based on the experimental results in a turning operation, Second, applying the sliding mode control theory to the turning operation model which is composed of the surface roughness model and the motor transfer function, the surface roughness is closed to the desired value. Finally, the effectiveness of this approach is demonstrated through the computer simulation.

• 한국지반공학회논문집
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• 제29권11호
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• pp.49-60
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• 2013

걸프지역 국가의 철도연계사업과 화물철도의 건설 등으로 인해 대형 철도사업의 발주가 이어지고 있지만, 중동지역 철도 시공 시 타 지역에서는 접하지 못한 특수한 지반조건으로 인한 리스크로 인하여 국내 업체들이 입찰에 어려움을 겪고 있다. 중동지역의 특수한 지반조건에 따른 주요 공학적 문제는 사브카 지반의 지반개량, 사막지역 모래바람 저감대책, 사막모래 다짐, 대규모 쌓기 및 깎기 등과 관련되어 있다. 본 논문에서는 현장조사 및 문헌조사, 현장시험 및 실내시험 결과 등을 토대로 중동지역에서 접할 수 있는 특수한 지반특성과 시공 상 리스크를 분석하고 대책을 논의하고자 한다.