후방 캔 압출 공정에서 표면 변형 형태에 대한 펀치 형상의 영향

노정훈(J. H. Noh),김동현(D. H. Kim),황병복(B. B. Hwang) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10

This paper is concerned with the analysis on the surface stress profiles of AISI 1015 steel in backward extrusion process. Heavy surface stress such as surface expansion appeared in backward can extrusion process usually leads to very severe tribological conditions along the interface between workpiece and punch land. In the present study, influence on the punch face angle and reduction has been investigated in terms of the surface stress profiles such as surface expansion, pressure exerted on the tool surface between tool and workpiece, respectively. The main goal of this study is to examine the influence of process conditions such as degree of reduction in area and geometries of punch face on the deformation pattern of the model material in backward extrusion, especially for surface stresses. It is well known that among various surface stresses, surface expansion and contact pressure distribution along the die-workpiece interface are closely related to the condition of lubrication at the interface for both solid and liquid lubricants, and contact pressure and sliding distance between workpiece and tool are essential parameters to evaluate the tool wear. The geometrical parameters employed in analysis include the punch face angle of the punch nose as well as reduction ratio. Extensive simulation has been conducted by applying rigid-plastic finite element method to backward can extrusion process under various geometrical conditions. The simulation results are summarized in terms of surface stresses such as surface expansion, pressure and comparison of surface loads for different process conditions, which constitute of surface stress profiles. It was found from the present study that the surface expansion is more influenced by reductions than the punch nose angle.

삼차원 표면 조도 측정기와 삼차원 레이저 공초점 현미경 적용에 따른 표면 거칠기에 대한 영향 연구

정희영,김대은 한국트라이볼로지학회 2024 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.40 No.2

Surface topography plays a decisive role in determining the performance of several precision components. In particular, the surface roughness of semiconductor devices affects the precision of the circuit. In this regard, the surface topography of a given surface needs to be appropriately assessed. Typically, the average roughness is used as one of the main indicators of surface finish quality because it is influenced by both dynamic and static parameters. Owing to the increasing demand for such accurate and reliable surface measurement systems, studies are continuously being conducted to understand the parameters of surface roughness and measure the average roughness with high reliability. However, the differences in the measurement methods of surface roughness are not clearly understood. Hence, in this study, the surface roughness of the back of a silicon wafer was measured using both contact and noncontact methods. Subsequently, a comparative analysis was conducted according to various surface roughness parameters to identify the differences in surface roughness depending on the measurement method. When using a 3D laser confocal microscope, even smaller surface asperities can be measured compared with the use of a 3D profiler. The results are expected to improve the understanding of the surface roughness characteristics of precision components and be used as a useful guideline for selecting the measurement method for surface topography assessment.

Tribological Behavior of Boundary Lubricated Sliding Surfaces Using Three Different Spacing of Surface Profiles

Oh, Se-Doo,Lee, Young-Ze The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.11

The ball-on-disk type sliding tests with boundary lubricated steels were carried out to verify the effect of initial spacing in surface profiles on wear and scuffing. Three kinds of surface spacing, which are closely related with initial surface micro-cracks on sliding surfaces, were produced on AISI 1045 steel surfaces using different grinding and polishing processes. Frictional forces and time to scuffing were measured, and the shape and amount of wear particles were analyzed to compare the with original surface profiles. From the tests, it was confirmed that the size of wear particles are related closely to the original spacing of the surface profile. The time to failure and amount of wear were sensitive to the surface spacing. The wider surface spacing shows much longer sliding life and smaller amount of wear than the others. Time to scuffing was increased with increasing surface pro(lie spacing. The size of wear particles increased while the wear and wear rate K were decreased with an increase in surface spacing. After the sliding tests, surface cracks of inner parts of the wear track formed due to scuffing were observed and compared among the specimens having the different surface spacing.

Nondestructive Inspection System Using Optical Profiles and Laser Surface Waves to Detect a Surface Crack

박승규,백성훈,Hyung-Ki Cha,정용무,강영준 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.1

An improvement of the detection efficiency for cracks is essential for a laser ultrasonic inspection system because it provides a relatively low signal-to-noise ratio when compared with conventional transducers. In this paper, a nondestructive inspection system using accumulated line profiles and multiple laser surface waves is configured to detect surface cracks. An optical line profile is used to detect a crack’s position, and multiple laser surface waves are adopted to accurately extract information on the crack’s depth. During a scanning test, multiple surface waves provide precise crack-depth information after a crack’s position is detected from an image of accumulated line profiles when a crack is positioned in the middle of multiple pulse laser beams. Multiple laser surface waves are composed of two parts, a reference part and a data part when a surface crack is positioned in the middle of these multiple pulse laser beams. Detailed crack-depth information can be extracted from the normalized multiple surface waves by referencing the reference part. The crack depth is proportional to the difference between the two peak frequencies of the reference and the data signals. With visual detection using an image of the accumulated line profiles, a nondestructive inspection system using multiple surface waves provides reliable surface-crack information.

감정노동의 사람 중심적 접근

양경욱(Kyunguk Yang),윤세준(Se Joon Yoon),채연주(Yeon Joo Chae) 대한경영학회 2016 大韓經營學會誌 Vol.29 No.9

Evaluation of the Applicability of Surface Wave Method on the Sloping Surface

Jong Tae Kim,Heon Joon Park,Dong Soo Kim,Sung Woo Kim 한국지반공학회 2011 international journal of geo-engineering Vol.3 No.4

Surface wave method has a great potential for rapid determination of shear wave velocity (Vs) profile of the ground. However, it has an inherent limitation in the interpretation of test results due to the assumption that the ground is layered horizontally. Numerical simulation using finite element method has been used to assess the effects of the sloping surface on wave propagation and dispersion characteristics. Finite element model was optimized for surface wave method to satisfy both accuracy and efficiency in the computation, and the applicability of finite element model for the surface wave test was verified by comparison of the dispersion curve with the theoretical solution. The effects of slope angle, stiffness contrast, and the testing direction on the dispersion curve were studied. The propagating shape of wave fronts in the sloping surface was also visualized. From the results of the numerical simulation, it was concluded that the Vs profile of material beneath the slope could be derived reasonably using a source and receiver aligned normally to the sloping surface. Field applications were performed to estimate the reliability of surface wave method on sloping ground. Through field applications and comparison with other test results, the accuracy and applicability of surface wave test on the sloping surface were verified.

Effects of a stylus on the surface roughness determination in a contact method for paper and paperboard

Jeong, Hyun Seok,Ko, Young Chan,Kim, Hyoung-Jin De Gruyter Oldenbourg 2019 NORDIC PULP AND PAPER RESEARCH JOURNAL Vol.34 No.4

<P><B>Abstract</B></P><P>Surface characterization is important and has many applications in the paper industry. It includes both surface roughness and surface friction. In determining the surface roughness of paper and paperboard, non-contact methods such as air-leak methods In characterizing the surface roughness of paper and paperboard, it has been a common practice that the average roughness with the coefficient of variation (COV) has been conventionally determined. This practice, however, this runs the risk of drawing wrong conclusions since two different surfaces having the same average roughness and COV can exhibit totally different properties. To avoid such mistake, a stylus-type contact method has been developed to determine surface roughness of paper and paperboard such as printing & writing (P&W), kraft and liners. In this method, surface roughness profile has been generated to determine its variability which has been defined as the mean deviation from the roughness average, referred to as MDRA. In determining the MDRA, it is noted that thickness measurement is not required. In this method, stylus shape and size, contact force of the stylus to the surface, scan speed and resolution have been identified as the key parameters of generating stable surface roughness profiles. It has been further identified that the optimal conditions on these parameters should depend on paper grade. It is suggested that a stylus-type contact method should be used to determine surface roughness of paper and paperboard to help determine their practical applications such as printing, coating and embossing.</P>

Profile-based Roughness Discrimination with Pen-type Texture Sensor

Ye, Xianming,Choi, Bynng-June,Kang, Sung-Chul,Choi, Hyouk-Ryeol 제어로봇시스템학회 2010 Transaction on control, automation and systems eng Vol. No.

Tactile discriminations of surface roughness using artificial sensors have been challenging. The modeling methods and parameters that have been using to describe the mechanical properties of rough surface are insufficient for haptic roughness. This paper proposes a method to characterize surface roughness based on the profiles of the surface. A compact handheld pen-type texture sensor with a right probe is developed for the measurement of surface profiles. Based on the contact force and the motion of the senor, profiles in the paths of scanning are estimated. The height variations of a profile are converted to a series of tactile stimuli to represent the contact stimulations in haptic explorations. The mean and the standard deviation of the amplitudes of stimuli are identified as haptic features that indicate the required tangential force to slide on the rough surface and how rough the surface is, respectively. Experiments show that the roughness on four kinds of sandpapers can he clearly distinguished by the proposed discrimination method.

Profile-based Roughness Discrimination with Pen-type Texture Sensor

최혁렬,최병준,강성철,Xianming Ye 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.4

Tactile discriminations of surface roughness using artificial sensors have been challenging. The modeling methods and parameters that have been using to describe the mechanical properties of rough surface are insufficient for haptic roughness. This paper proposes a method to characterize sur-face roughness based on the profiles of the surface. A compact handheld pen-type texture sensor with a right probe is developed for the measurement of surface profiles. Based on the contact force and the motion of the senor, profiles in the paths of scanning are estimated. The height variations of a profile are converted to a series of tactile stimuli to represent the contact stimulations in haptic explorations. The mean and the standard deviation of the amplitudes of stimuli are identified as haptic features that indicate the required tangential force to slide on the rough surface and how rough the surface is, respectively. Experiments show that the roughness on four kinds of sandpapers can be clearly distin-guished by the proposed discrimination method.

Evaluation of Predicted Pavement Fatigue Life Based on Surface Profiles and Asphalt Mixture Types

박대욱 대한토목학회 2010 KSCE JOURNAL OF CIVIL ENGINEERING Vol.14 No.2

The objective of this study is to evaluate pavement fatigue of both the 12.5 mm+PG58-22 and 12.5 mm+PG64-22 asphalt mixtures by evaluation of the pavement damage index, which is calculated based on the simulated dynamic load and the fracture parameter. The pavement damage index is the change in the pavement fatigue life between a target profile and an as-built profile. To achieve the objective, the dynamic load was simulated based on the pavement surface profile, vehicle speed, and vehicle suspension. The dynamic load increases when the surface profile is rougher, while the incensement of the dynamic load on rougher pavements is accentuated when the speed is higher. For the two asphalt mixtures, the coefficient of variance of the simulated dynamic load and the fracture parameter, which is calculated from the slope of the linear portion of the creep compliance, are used to calculate the pavement damage index. The pavement damage index increases as both the variance of the dynamic load and the confidence level increase. At lower temperatures, the value of n increases. This result indicates that, as the temperature decreases, a larger reduction in the fatigue life of the pavement is expected for the same pavement surface profiles. The 12.5 mm+PG64-22 asphalt mixture has a larger reduction in the pavement fatigue life than the 12.5 mm+PG58-22 asphalt mixture.