• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.11
• /
• pp.1633-1639
• /
• 2013

In a section of AC electric railway, a phase between the sections is different although voltage levels supplied from substations are the same. Therefore, section insulators have been installed to electrically divide between the sections. Two differenet types of section insulator, namely an overlap type and insulator type, are used. In Korean high-speed lines, overlap type section insulator has been adopted. And, insulator type is used in conventional line. The overlap type has the advantage of having no speed limit, but has the disadvantage of requiring long section length. However, the insulator type has the advantage of section length, but also has the disadvantage of having speed limit. In Korean conventional line, an insulator type one relies on the import and there is some problem with wear. In this study, we developed the insulator type section insulator which adopts Teflon tube insulation material. The Teflon material has advantage of the excellent electrical characteristics and wear-resistance characteristics for a longer expected life than that made of existing FRP. In order to compare wear characteristics between the materials, wear tests with reciprocal wear tester are performed. And dynamic behavior tests between the insulators and pantograph are also performed for showing its better dynamic characteristics.

• The Research Journal of the Costume Culture
• /
• v.28 no.1
• /
• pp.131-145
• /
• 2020

As the population of consumers of outdoor wear expands, there is increasing interest among consumers in trendy lifestyle outdoor. Accordingly, it is essential to develop designs that are drawn from outdoor wear. This can be limited to traditional mountaineering suits, and designs developed from men's outdoor zip-up T-shirts, which are highly utilized in everyday life, are very important. This study developed the design of a summer zip-up T-shirt for men with both functional and aesthetic qualities. Visual images of foreign brands and domestic outdoor-focused T-shirts from the spring/summer seasons of 2013-2019 were collected to analyze the following modeling elements: silhouettes, details, colors, materials, and prints. In addition, the design concept was derived by analyzing presentations from the global outdoor trade Fairs (2013-2019). To develop a sustainable eco-friendly outdoor summer T-shirt for men, the concept was derived according to three categories: eco-friendly, sportism-expressed active elements of sports, and an outro-concept of urban town wear as an outdoor lifestyle. Thus, a total of 12 styles of design were developed. High utilization of the outdoor wear T-shirts (which are also popular as lifestyle wear), is an important aspect of building a segmented lineup of the slow-growing outdoor wear market and supports expansion of the scope of theoretical research on outdoor wear design.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.8
• /
• pp.1287-1294
• /
• 2003

The wear process of end mill is so complicated process that a more reliable technique is required for the monitoring and controlling the tool life and its performance. This research presents a new tool wear monitoring method based on the sound signal generated on the machining. The experiment carried out continuous-side-milling for 4 cases using the high-speed-steel end mill under wet condition. The sound pressure was measured at 0.5m from the cutting zone by a dynamic microphone, and was analyzed at frequency domain. As the cutter impacts the workpiece surface, a situation of farced vibration arises in which the dominant forcing frequency is equal to the tooth passing frequency of the cutter. The tooth passing frequency appears as a harmonics form, and end mill flank wear is related with the first harmonic. It is possible to detect end . mill flank wear. This paper proposed the new method of the end mill wear detection.

• Tribology and Lubricants
• /
• v.33 no.1
• /
• pp.31-35
• /
• 2017

Recently, international attention has been focused on the development of non-traditional energy resources such as shale gas and oil sands, due to the steep increase in the demand for natural resources. The materials incorporated in an oil gas plant module experience extreme environments, and are prone to various problem such as fracture, corrosion and abrasion due to low-temperature brittleness. In order to improve the plant life, it is necessary to perform characteristics study and performance evaluation of the materials. In particular, this paper explains the main set of materials which are most frequently used in oil sands plant project. In order to investigate wear characteristics, the authors carried out abrasive wear tests of TP 316, stainless steel and SS 400, structural rolled steel. For the analysis of the abrasive wear resistance of an oil sands plant, the authors carried out the test according to ASTM G 105 "Standard Test Method for Conducting Wet Sand/Rubber Wheel Abrasion Test" standard guidelines. The authors have derived the results from the data associated with the loss of mass with respect to wear rate. During the test, for a given wear length for 10,000 revolutions, the rotational speed and applied force of the rubber wheel were varied.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.3
• /
• pp.43-50
• /
• 1998

In the use of CNC machine tool, the unmanned production system has been growing in the manufacturing field. Thus, it is necessary to monitor adequate tool fracture during the cutting process efficiently. This experimental study is intended to investigate the development of flank wear in sysnchronous turning of differential materials(Aℓ/GC) which is used in industrial application and it is acknowledged as a machine to difficult material. In cutting process change of velocity, change of feed, and change of depth of cut were investigated on the effect of flank wear, and slenderness ratio is also investigated. The conclusions of this paper are summarized as follows; 1.Under the high cutting speed condition, the flank wear is affected by the feed and depth of cut. but the influence of feed on the flank wear is larger than the depth of cut and that is reduced when the velocity is low. 2.Under the high cutting speed, as the smaller slenderness ratio is, the shorter tool life is under the lower cutting speed, the effect of slenderness ratio on the flank wear is low. 3.Using the characteristics of cutting force, the flank wear of a tool can be detected 4. Investigating the development of flank wear, there are almost no differences between the characteristics of cutting force and feed force. Finally, these data from the differntial materials cutting process will be used in the basic field of precision and economic cutting process.

• Journal of the Korea Society of Computer and Information
• /
• v.20 no.11
• /
• pp.1-8
• /
• 2015

Flash memory has advantages in that it is fast access speed, low-power, and low-price. Therefore, they are widely used in electronics industry sectors. However, the flash memory has weak points, which are the limited number of erase operations and non-in-place update problem. To overcome the limited number of erase operations, many wear leveling techniques are studied. They use many tables storing information such as erase count of blocks, hot and cold block indicators, reference count of pages, and so on. These tables occupy some space of main memory for the wear leveling techniques. Accordingly, they are not appropriate for low-power devices limited main memory. In order to resolve it, a wear leveling technique using bit array and Bit Set Threshold (BST) for flash memory. The proposing technique reduces the used space of main memory using a bit array table, which saves the history of block erase operations. To enhance accuracy of cold block information, we use BST, which is calculated by using the number of invalid pages of the blocks in a one-to-many mode, where one bit is related to many blocks. The performance results illustrate that the proposed wear leveling technique improve life time of flash memory to about 6%, compared with previous wear leveling techniques using a bit array table in our experiment.

• Journal of Fashion Business
• /
• v.23 no.6
• /
• pp.127-138
• /
• 2019

As health and well-being become a global trend, the younger generation is focusing on the balance between work and leisure time and they are interested in sports activities as well as a cultural life. In addition, the range of sportswear is expanding, so that athleisure fashion is getting into daily lives. In particular, consumer groups in the sportswear market are beginning to change since generation Z consumers are more and more interested in sportswear and their needs are also growing of health and functional of sports wear. It's a global trend that athleisure fashion market is growing, which combines professional athletic wear with fashion. As the number of women who enjoy sports and leisure in their spare time, the consumer pattern in the sports wear market is also expanding to female customers. However, most sports functional wears were focused on male consumers, so that functional inner-wears are mostly made for both sexes, which mean the functional inner-wears are produced without considering the physical characteristics of men and women and with not enough size division ending up not suitable for professional athletes. In particular, female professional athletes need functional inner-wear that fits the characteristics of the sport because they are not only different in physical condition and they are also using different muscles for different movements. Therefore, functional inner-wear needs pattern development and size system setting considering the body shape and athletic movement of female professional athlete.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.99-104
• /
• 2003

TiN coated films show a good mechanical properties, high thermal properties and wear, erosion and corrosion resistance and are widely used as a coating materials in tools, ornaments, parts and semiconductors. In spite of these good properties, the fracture of TiN coated films occur during use. The fracture of TiN thin films is related to their microstructure. Especially, the life of TiN coated layer is related to the texture of the TiN films. One researcher suggested that the corrosion and erosion resistance of the TiN thin films is related to a uniform and dense structure of films. In this study, we studied the relationships between textures and friction coefficient, erosion and corrosion in TiN coated films. The flatness of (115) texture surface of TiN thin films is flatter than that of (111) texture surface. The friction coefficient of (115) texture surface of TiN thin films is similar with that of (111) texture surface. The wear resistance of (115) texture surface of TiN thin films is better than that of (111) texture surface. The erosion and corrosion resistance of (115) texture surface of TiN thin films is better than that of (111) torture surface. As well as texture, the wear, erosion and corrosion of TiN thin films has to consider defects such as pinholes, cracks, surface roughness and open columnar structure. The life of TiN coated products is influenced by the properties of wear, erosion, and corrosion resistance of TiN thin films and is related to texture of TiN coated films, density of pinholes and cracks, density of structure, and surface flatness.

• Tribology and Lubricants
• /
• v.16 no.2
• /
• pp.121-125
• /
• 2000

Silicon nitride ceramic has been verified as an excellent rolling bearing material because of its high strength and outstanding rolling fatigue life properties. However under some corrosive circumstances it showed drawbacks such as hardness reduction and severe wear caused by corrosion. In this work, the variations of the rolling wear and hardness of three kinds of ceramics were studied for the specimen aged 15 days in alkali water (90 $\pm$ 2$\^{C}$,25 wt% NaOH ). All of the specimens, ① Si$_3$N$_4$, ② 3Y-TZP and ③ 3Y-TZP alloyed with 5 wt% CeO$_2$, were sintered and post-HIPed, and then polished up to 0.02 $\mu$mRa of surface roughness. Rolling wear tests were conducted by MJ type rolling fatigue life tester under the initial theoretical maximum contact stress of 3.16 GPa and the spindle speed of 1,000 rpm. Spindle oil was used as a lubricant. The specimens were not worn before aging. For the specimen aged in alkali water, Si$_3$N$_4$ and 3Y-TZP were worn by rolling wear tests, and hardness was decreased. While aging the specimens, the phase was transformed from tetragonal to monoclinic in 3Y-TZP and the microstructure change occurred in Si$_2$N$_4$. 3Y-TZP specimens alloyed with 5 wt% CeO$_2$ were not worn after aging and no phase transformation occurred while aging.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1999.11a
• /
• pp.154-159
• /
• 1999

Silicon nitride ceramic has been verified as an excellent rolling bearing material because of its high strength and outstanding rolling fatigue life properties. However under some corrosive circumstances it showed drawbacks such as hardness reduction and severe wear caused by corrosion. In this work, the variations of the rolling wear and hardness of three kinds of ceramics were studied for the specimen aged 15 days in alkali water (90$\pm$2$^{\circ}C$, 25 wt% NaOH). All of the specimens, \circled1Si$_3$N$_4$, \circled23Y-TZP and \circled33Y-TZP alloyed with 5 wt% CeO$_2$, were sintered and post-Hipped, and then polished up to 0.02 ${\mu}{\textrm}{m}$Ra of surface roughness. Rolling wear tests were conducted by MJ type rolling fatigue life tester under the initial theoretical maximum contact stress or 3.76 Gra and the spindle speed of 1,000 rpm. Spindle oil was used as a lubricant. The specimens were not worn before aging. For the specimen aged in alkali water, Si$_3$N$_4$and 3Y-TZP were worn by rolling wear tests, and hardness was decreased. While aging the specimens, the phase was transformed from tetragonal to monoclinic in 3Y-TZP and the microstructure change occurred in Si$_3$N$_4$. 3Y-TZP alloyed with 5 wt% CeO$_2$specimens were not worn after aging and no phase transformation occurred while aging.