• 한국공작기계학회논문집
• /
• 제12권4호
• /
• pp.9-16
• /
• 2003

In this study, the decision of dressing time for diamond wheel was analyzed by observing with acoustic emission signals and surface roughness, and also obtained the machining characteristics by weibull distribution plot for the values of bending strength. From the experimental study, it was possible to predict the time of re-dressing for the diamond grinding wheel with the analysis of acoustic emission signals and surface roughness values, and following conclusions were obtained. The root-mem-square values of acoustic emission signals were obtained low as the increased of table speed for different abrasive grain size. This is caused by the lack of grinding power which is not able to get rid of all real grinding mass of depth as the table speed is increased. The values of bending strength for ground $Si_3 N_4$ specimens were decreased for gain size of #400 than that of #60, but it was found that the surface roughness values for gain size of #60 were better than that of #400. As compared the shape parameter of weibull distribution plot for the values of bending strength, it was found that the reliability of bending strength for grain size of #60 increased than that of #400.

• 한국생산제조학회지
• /
• 제22권2호
• /
• pp.223-227
• /
• 2013

Dust collecting performance of cyclone collector for oil mist was alalyzed in the study. The purposes of using cutting fluid during cutting have been colling, lubricating, chip washing and anti-corroding. However, the present manufactaring industry restricts the use of cutting fluid because cutting fluid confains poisonous substances which are harmful to the human body. Also, the optimum design oil-mist collector. The new oil mist collector was designed. In the near future, this device must be tested in the real machining center and CNC machine. Cutting using oil-mist showed better cutting characteristics than dry, air and fluid cutting with respect to by cutting force, tool wear and surface roughness. The model(A, B Type cyclone) of the set of fixture and alveolus are made by using a CAE software. Finally, we have obtained a model A Type solution by using orthogonal array. Therefore, it could be confirmed that as the model-A was increased and model-B was decreased, cut diameter was decreased.

• Tribology and Lubricants
• /
• 제29권4호
• /
• pp.213-217
• /
• 2013

As commercial atomic force microscopy (AFM) probes made of Si and $Si_3N_4$ have low stiffness, it is difficult to induce sufficient elastic deformation on the surface of a specimen in a tapping mode. Therefore, high-guality phase contrast images can not obtained. On the other hand, a tungsten AFM probe has relatively higher stiffness than a commercial AFM probe. Accordingly, it is expected to provide an enhanced phase contrast image, which is an effective tool for achieving a better understanding of the micromechanical properties of worn surfaces and wear mechanisms. In this study, on electrochemical etching method was optimized to fabricate tungsten probe tips for an AFM. Electrochemical etching was performed by applying pulse waves with a 20% duty cycle at various voltages instead of only a DC voltage, which has been commonly used.

• 대한임베디드공학회논문지
• /
• 제11권2호
• /
• pp.87-95
• /
• 2016

Nonvolatile memory (NVM) is being considered as an alternative of traditional memory devices such as SRAM and DRAM, which suffer from various limitations due to the technology scaling of modern integrated circuits. Although NVMs have advantages including nonvolatility, low leakage current, and high density, their inferior write performance in terms of energy and endurance becomes a major challenge to the successful design of NVM-based memory systems. In order to overcome the aforementioned drawback of the NVM, extensive research is required to develop energy- and endurance-aware optimization techniques for NVM-based memory systems. However, researchers have experienced difficulty in finding a suitable simulation tool to prototype and evaluate new NVM optimization schemes because existing simulation tools do not consider the feature of NVM devices. In this article, we introduce a NVM-based cache simulator to support rapid prototyping and evaluation of NVM-based caches, as well as energy- and endurance-aware NVM cache optimization schemes. We demonstrate that the proposed NVM cache simulator can easily prototype PRAM cache and PRAM+STT-RAM hybrid cache as well as evaluate various write traffic reduction schemes and wear leveling schemes.

• 한국공작기계학회논문집
• /
• 제15권2호
• /
• pp.51-58
• /
• 2006

Laser welding of dissimilar metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for SM45C and STS304 with CW Nd:YAG lasers. The bead-on-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the dissimilar welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding qualify is 1600W of the laser power, 0.85m/min of welding speed and $4{\ell}/min$ of pressure for shielding gas.

• Tribology and Lubricants
• /
• 제11권5호
• /
• pp.99-107
• /
• 1995

This paper reported research results to develop an algorithm of on-lin evaluation of surface profiles and roughness generated by turning. The developed module consisted of computer simulation of surface profiles using mechanism of cutting mark formation and cutting vibrations, and online measurement of cutting vibrations. The relative cutting vibrations between tool and worpkiece were measured through an inductance pickup at the rate of one sample per rotation of the workpiece. The sampling process was monitored using an encoder to avoid conceling out the phase lag between waves. The digital cutting signals from the Analog-to-Digital converter were transferred to the simulation module of surface profile where the surface profiles were generated. The developed algorithm or surface generation in a hard turning was analyzed through computer simulations to consider the stochastic and dynamic nature of cutting process. Cutting tests were performed using AISI 304 Stainless Steel and carbide inserts in practical range of cutting conditions. Experimental results showed good correlation between the surface profiles and roughness obtained using the developed algorithm and the surface texture measured using a surface profilemeter. The research provided the feasibility to monitor surface characteristics during tribelogical tests considering wear effect on surface texture in machining.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
• /
• pp.349-354
• /
• 2000

A use of Titanium alloy as a structural material is increasing lately. Among those titanium alloys, Ti-6A1-4V alloy is the most popular one with taking 2/3 of it's market. Also, Ti-6A1-4V alloy can get the stability of organization and product measure, and the evaluation of the cutting ability and the mechanical characteristics. The point in titanium alloy work is on how treat the heat generated during grinding. Because the heat conductivity of titanium alloy is unnegligibly low, the grinding heat is accumulated in workpiece, and it cause the increasing of grinding grits' wear and the rough grinding surface. So, these characteristics in grinding of titanium alloy will change the mechanical characteristics of the titanium alloy. From this study, the mechanical characteristics of annealed Ti-6A1-4V alloy after grinding was concerned with checking out the bending strength values, and the factor of the change and the difference was analyzed after analyzing the surface roughness and the image from SEM.

• 한국레이저가공학회지
• /
• 제12권4호
• /
• pp.12-16
• /
• 2009

The engineering ceramic is one of the materials advantageous in various conditions with high strength, endurance at high temperature, abrasion resistance and corrosion resistance, etc. However, due to high strength and high brittleness, ceramic incurs high costs and long time on finishing process required after sintering. So a process for obtaining wanted measurements of them has been studied using the high temperature which makes ceramics softened and heat affected recently. This study makes an estimate of laser-assisted machining (LAM) if an economically practical process for manufacturing precision silicon nitride ceramic parts using laser beam. In this study, mechanical properties of silicon nitride at high temperature were observed. And during the LAM, it was observed that cutting force and tool wear were reduced and oxidation of machined surface was increased according to a increase of laser power.

• 한국의류산업학회지
• /
• 제4권1호
• /
• pp.47-55
• /
• 2002

This paper is to study pertinent consumer evaluations and preferences of fashion depending upon human sensibility. Focus is placed on quantifying consumer's sensibility through the sensibility analysis of men's fashion. The subject are 227 male and female university students of who take the course of "Modern Life and Fashion" and "Understanding of Colors" in the OCU Cyber University. Data has been collected by survey method and subsequently analyzed and interpreted. To measure consumer's consuming sensibility, G-Sensibility tool developed by 'Fuji Central Institute' has been employed. The results of the analysis of ANOVA and MANOVA show significant differences among the following 5 styles: Active style G2, Open-minded style of G-3, Mania style of G4, Sensitive and emotional style of G5. According to ${\chi}^2$ test, the results show that the distinction of sex and their interests in fashion are significant different. The evaluation of men's fashion, according to Multi-dimensional test, shows a variety of differences according gender and G sensibility styles. These varied distinctions are illustrated statistical in Picture 1, Picture 2, Picture 3, Picture 4, Picture 8, and picture 10. Based art the results, a follow-up study to develop the case study and the apply it's results are recommended to produce products placed in the market.

• 한국레이저가공학회지
• /
• 제12권1호
• /
• pp.25-33
• /
• 2009

In laser-assisted machining (LAM), laser beam is used to locally increase the temperature of a workpiece and thus to enhance the machinability. In order to set the temperature of the material removal area of a workpiece at an optimal value, process parameters, such as laser power, feed rate, and rotational velocity, have to be carefully controlled. In this work, the effects of laser power and feed rate on the temperature distribution of a silicon nitride rotating at a constant velocity were experimentally investigated. Using a pyrometer, temperatures at various locations of the silicon nitride were measured both in circumferential and axial directions. The measured temperatures were fitted to a quadratic equation to approximate the temperature at the cutting location. The machining results showed that cutting force and tool wear were decreased when the temperature at the cutting location was increased.