• 한국철도학회:학술대회논문집
• /
• 한국철도학회 1999년도 춘계학술대회 논문집
• /
• pp.398-405
• /
• 1999

Large dynamic forces are generated between wheel and rail due to rail surface irregularities at rail welded part. The effects become more and more significant in the view of the present tendency to train speed increasing. Therefore, the purpose of this paper is to derive useful guides for the effective and economical maintenance of rail welded parts through the wheel and rail interaction analyses. A typical shape for the irregularity of rail welded part is assumed to make the analysis quantitative. The effects of the irregularity depth and train speed on the train and track behaviors are investigated.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 춘계학술대회 논문집
• /
• pp.281-285
• /
• 2008

The railroad roadbed plays an important role in distributing and transferring the train loading to subgrade, preventing subgrade from bearing softened by providing appropriate stiffness for subgrade, and eventually supporting the track structures. Presently, the reinforced roadbed was widely constructed in high speed line and is proceeding a research about economical thickness and methodologies for the design of reinforced roadbed. Field test section is located at Kyungbu line which is from Suwon to Cheonan In this study, field test were measured a track irregularity with several types of reinforced roadbed materials by using Track Master. The field testing were conducted between March, 2006 and April, 2008.

• 대한공간정보학회지
• /
• 제11권1호
• /
• pp.77-82
• /
• 2003

GIS는 지금까지 여러 학계를 걸쳐서 응용단계에 접어들었으며, 특히 토목분야에서도 많은 응용을 하고 있다. GIS를 이용한 공간분석에서 지형을 정확하게 표현하는 것은 매우 중요하며 향후 3차원적 해석을 하기 위해서는 중요한 인자가 될 수도 있다. 이러한 지형을 표현하기 위해 주로 불규칙삼각망을 이용하고 있다. 따라서 본 연구에서는 불규칙삼각망에 의한 지형의 체적을 개발된 식에 의하여 산정을 하였다.

• 한국표면공학회지
• /
• 제43권1호
• /
• pp.12-16
• /
• 2010

The morphology of the passivated surface of stainless steel (SS) was quantitatively characterized based on fractal geometry. In particular, the surface irregularities of the passivated 304 and 439 SSs were comparatively analyzed in terms of their self-similar fractal dimensions. The passivated surface of 439 SS in an acid-based electrolyte proved to have a higher fractal dimension, as compared to that of 304 SS, esp. at a scale of several tens of nanometers, strongly indicating the higher irregularity of the passivated surface. It is anticipated that the fractal approach suggested herein might be effectively utilized to analyze the irregularity of the steel surface and/or the compactness of the oxide film.

• 대한산업공학회지
• /
• 제23권2호
• /
• pp.403-420
• /
• 1997

In this paper, we examine the effect of production uncertainty to production control policies. First, we examine two famous production control policies, namely, MRP and JIT from the view point of shop floor control perspective, and analyze the differences between them due to demand fluctuations and activity time variations. Second, we conduct simulation studies on MRP and JIT to draw out the effects of demand fluctuations and activity time variations. Demand fluctuations are further classified into demand lumpiness and demand irregularity. And, activity time variations are further classified into stationary time variations and non-stationary time variations. Experimental results show that, in terms of demand fluctuations, MRP is affected by demand lumpiness, but JIT by demand irregularity. And we also see that both MRP and JIT are influenced by stationary time variation with respect to activity time variations.

• Journal of Advanced Marine Engineering and Technology
• /
• 제22권4호
• /
• pp.522-528
• /
• 1998

This paper presents a fundamental fractal characteristics of the growing crack that has an irregularity producing a zigzag crack contour. This irregularity is analysed by a fractal geometry in a box counting method that is a very simple technique. First the fractal dimensions and actual fractal extensive crack length are obtained. Also a fractal fracture energy relation with a fractal dimension is found so as to get fractal crack behaviors. Thus it can be shown that the fractal dimension has a possibility as a fracture parameter in a real crack growth length meaning.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.555-564
• /
• 2001

Wheel-rail noise is normally classified into three catagories ： rolling, squeal and impact noise. In this paper, rolling noise caused by the irregularity between a wheel and rail is analysed as follows： The irregularity between the wheel and rail is assumed as combination of sinusoidal profiles. Wheel-rail contact stiffness is linearized by using Hertzian contact theory, and then contact force between the wheel and rail is calculated. Vibration of the rail and wheel is calculated theoretically by receptance method or FEM depending on the geometry of wheel or rail for the frequency range of 100-5000Hz, important for noise generation. The radiation caused by those vibration is computed by BEM. To verify this analysis tools, rolling noise is calculated by preceding analysis steps using typical roughness data and it is compared with experimental rolling noise data. This analysis tools show reasonable results and used for the prediction of KTX rolling noise.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2003년도 춘계 학술발표회논문집
• /
• pp.321-328
• /
• 2003

The objective of this study is to investigate the seismic response of high-rise RC bearing-wall structures with irregularity. For this purpose, three 1:12 scale 17-story reinforced concrete model structures were constructed according to the similitude law, in which the upper 15 stories have a bearing-wall system while the lower 2-story frames have three different layouts of the plan : The first one is a moment-resisting frame system, the second has a infilled shear wall with symmetric plan and the third has a infilled shear wall with eccentricity, Then, these models were subjected to a series of earthquake excitations. The test results show the followings: 1) the existence of shear wall reduced greatly shear deformation at the piloti frame, but has almost the negligible effect on the reduction of the overturning-moment angle, 2) the frame with shear wall resists most of overturning moment in severe earthquake, 3) the torsional behavior is almost independent of the translational, 4) the absorbed energy due to the overturning deformation has the largest portion in the total absorbed energy.

• 대한조선학회논문집
• /
• 제40권3호
• /
• pp.45-53
• /
• 2003

Ships and ocean structures are subjected to random loads caused by irregular waves. The irregularity of amplitude from random loading affects on fatigue crack growth and fatigue life. However the effects of irregularity of loading on fatigue including random loading have not been explained exactly. Therefore in this paper crack growth tests on DENT specimens under constant-amplitude loading including a single tensile overload are conducted to investigate the effect of overload on crack growth rate. The size of plastic zone and crack growth rate before and after a single tensile overloading are measured using ESPI system. Crack growth retardation model that is characterized by crack growth length and the size of plastic zone was proposed and compared with test result. From the research, the validity of proposed model is examined on crack growth retardation, and consequently fatigue life.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.474-477
• /
• 2006