• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.228-236
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• 2002

In this study, the carbon steels, SM20C were machined with the tungsten carbide tipped circular saw to clarify the cutting-off characteristics in terms of tool wear. The results show that an improved performance in view of both the tool wear and the cutting efficiency was obtained by using oil base cutting fluid at the cutting speed of 100m/min with the feed of 0.06mm/tooth. The rake angle of 10$^{\circ}$ , clearance angle of 8$^{\circ}$ , nose radius of R0.1mm, and end cutting edge champer of 0.1mm$\times$25$^{\circ}$ are believed as the best tool geometries. The tool wear decreases due to using the saw of the disk of STS5 and the tool material of P30.

• Tribology and Lubricants
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• v.12 no.3
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• pp.6-11
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• 1996

There has been a growing concern for the use of mineral oil based lubricants because of the worldwide interest in environmental issues. This has prompted the use of vegetable oils as more environmentally acceptable base fluids. In view of this, four-ball wear test was carried out to investigate the tribological behavior of selected vegetable oils blended with ZDDP, TCP and DBP under high speed and temperate conditions. Of the additive evaluated, the new additive, DBP has provided antiwear performance superior to the two other additives more commonly used. This superior performance by DBP is probably caused by different wear mechanism. This wear mechanism has been evidenced by the surface analysis of worn balls conducted using optical microscope and EDAX.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.135-142
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• 2000

This Paper describes a characteristics of wheel wear of high speed train running on the conventional line. Conventional line has many curved tracks that cause severe wheel flange wear. The influences of lubrication, cant deficiency, owe radius on wheel wear are also described considering the operation performance of the highspeed trainset. A method of calculation using contact patch work model is presented far determination of the evolution by wear of railway wheels.

• Journal of the Korean Home Economics Association
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• v.34 no.3
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• pp.259-269
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• 1996

The purpose of this study was to investigate on wear performance of four type of stocking: support, mono, panty, bane stocking. Major results are as follows; 1)The most subjects tended to be unsatisfied on wear performance of stocking. 2)Generally, the subjects tend to more satisfied support stocking than mono, and panty stocking than band. 3)It showed that ideal sensory sensation on wearing of stocking were d dry, softness, fittness. 4)It showed that ideal visible sensationon on wearing of stocking were thinness, refresh feeling, attractiveness, commonness

• Journal of the Korean Society of Costume
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• v.60 no.5
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• pp.88-105
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• 2010

The purpose of this study is to grasp the actual wearing conditions, inconvenience and problems with cycle wear. To attain this purpose, a questionnaire was completed by direct observation and by interviewing bicyclists. The questionnaire was given to 273 bicyclists. The questionnaire consisted of items that are related to concerns with dressing appropriately and enhancement of physical performance through dress. Following are the results of this study. According to the survey, many of them purchased imported cycle wear rather than national cycle wear, and the satisfaction according with purchase rate was low. Bicyclists were uneasy with finding right size cycle wear especially for women. It turned out that the area of the knee and elbow are mostly the areas that they get hurt while riding. Even though the knee and elbow are the mostly hurt area, bicyclists do not prefer to wear appropriate protector for the knee and elbow to excel in their performance in cycling. In material related questions, lower dissatisfaction was indicated for the lints caused by fraction. Average satisfaction was indicated for the distortion after washing, changes in color, touch of the fabric, matters with static and sweat. With regard to the areas where the bicyclists felt discomfort was highly indicated with lower-body clothing. Discomfort was highly indicated with crotch area when riding long period of time. Also when riding a cycle, discomfort was indicated with the leggings cuffs when it comes upward with riding motion. Most of the bicyclists felt the tight fitting leggings were embarrassing.

• Tribology and Lubricants
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• v.17 no.2
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• pp.109-115
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• 2001

The lubricating performance of 23 kinds of polyol ester base oils 〔POEs〕 having different branch shapes was investigated by using a four ball tribometer under boundary lubrication condition. All the polyol ester base oils used in this study were made up of polyhydric alcohols of two-four valence and normal or branched fatty acids of different carbon number. The wear characteristics of polyol ester base oils are different from those of mineral oil, strongly affected by the branch shapes of fatty acids in their molecles. In particular, the polyol ester base oils having normal fatty acids such as n-octanoic acid, n-nonanoic acid etc. show much better wear performance than POEs having branched fatty acids such as 2-ethylhexanoic acid, 3,5,5-trimethyl hexanoic acid, etc. As the carbon chain length of normal fatty acids, in case of POEs of normal fatty acids, is increased, their wear rate is decreased and, in case of POEs of branched fatty acids, as the degree of branch of branched fatty acids is decreased, their wear rate is decreased. All the wear results of polyol ester base oils could be reasonably explained by comparing cohesive ability among fatty acid molecules in adsorption film by fatty acids obtained as POEs were decomposed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.3-8
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• 1996

To enhance the cutting performance of the tool, single or multilayer coating is applied on the substrate of the tool. Coating material reduces cutting force and heat generation in tool-chip contact zone and enhances resistance against abrasive wear. This paper presents that the effect of different coatings on abrasive wear resistance varies with work material and the flank wear rate is different with depth of cut. Crater wear rate is also found to decrease with higher thermal diffusivity of coating material. It is verified that the estimated thermal diffusivity of multilayer coating has consistent effect on the crater wear.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.182-189
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• 2001

TiCN based submicron cermet and similar ISO grad of the conventional cermets with TiCN of different particle size were produced by PM process, and their microstructure, mechanical properties and cutting performance were compared. The microstructure of submicron cermet was more homogeneous and showed much finer microstructure, resulting in better hardness and fracture toughness. The submicron cermet tools achieved excellent cutting performance such as wear resistance and toughness in comparison with two grades of the conventional cermets in millimg test. The relationship between microstrucure, mechanical properties and cutting performance of these cermet tools was discussed. The submicron cermet tools revealed for their potential to wide application range and interrupt cutting because of their superior wear resistance and toughness combinations.

• Journal of the Korea Society of Computer and Information
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• v.20 no.12
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• pp.1-8
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• 2015

Wear leveling techniques have been studied to prolong the lifetime of NAND flash memory. Most of studies have used Program/Erase(P/E) cycles as wear index for wear leveling. Unfortunately, P/E cycles could not predict the real lifetime of NAND flash blocks. Therefore, these algorithms have the limited performance from prolonging the lifetime when applied to the SSD. In order to apply the real lifetime, wear leveling algorithms, which use raw Bit Error Rate(rBER) as wear index, have been studied in recent years. In this paper, we propose CrEWL(Cold data identification using raw Bit error rate in Wear Leveling), which uses rBER as wear index to apply to the real lifetime. The proposed wear leveling reduces an overhead of garbage collections by using HBSQ(Hot Block Sequence Queue) which identifies hot data. In order to reduce overhead of wear leveling, CrEWL does not perform wear leveling until rBER of the some blocks reaches a threshold value. We evaluate CrEWL in comparison with the previous studies under the traces having the different Hot/Cold rate, and the experimental results show that our wear leveling technique can reduce the overhead up to 41% and prolong the lifetime up to 72% compared with previous wear leveling techniques.

• Journal of Powder Materials
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• v.15 no.5
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• pp.359-364
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• 2008

To satisfy the demand of higher cutting performance, mechanical properties with tungsten carbide (WC-Co) tool materials were investigated. Hardness and transverse rupture strength with WC grain size, Co content and density were measured. Compared to H, K, and S manufacture maker as tungsten carbide (WC-Co) tool materials were used for high-speed machining of end-milling operation. The three tungsten carbide (WC-Co) tool materials were evaluated by cutting of STD 11 cold-worked die steel (HRC25) under high-speed cutting condition. Also, tool life was obtained from measuring flank wear by CCD wear measuring system. Tool dynamometer was used to measure cutting force. The cutting force and tool wear are discussed along with tool material characteristics. Consequently, the end-mill of K, H manufacture maker showed higher wear-resistance due to its higher hardness, while the S maker endmill tool showed better performance for high metal removal.