• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1859-1863
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• 2007

A new type of a fretting wear tester has been designed and developed in order to simulate the actual vibration behavior of a nuclear fuel rod for springs/dimples in room temperature. When considering the actual contact condition between fuel rod and spring/dimple, if fretting wear progress due to the flow-induced vibration (FIV) under a specific normal load exerted on the fuel rod by the elastic deformation of the spring, the contacting force between the fuel rod and dimple that were located in the opposite side should be decreased. Consequently, the evaluation of developed spacer grids against fretting wear damage should be performed with the results of a cell unit experiments because the contacting force is one of the most important variables that influence to the fretting wear mechanism. Therefore, it is necessary to develop a new type of fretting test rig in order to simulate the actual contact condition. In this paper, the development procedure of a new fretting wear tester and its performance were discussed in detail.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.31-36
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• 2004

In this paper, fretting wear tests were conducted in air at room temperature (RT) and in water at high temperature and high pressure (HTHP) environment to analyze the wear characteristic. As for the supporting condition between the tube and spring/dimple, the gap of 0.2 mm in air at RT and the normal force of 10 N and the slip of $50\;{\mu}\;m$ in water at HTHP were applied. Four different shapes of spring/dimple specimen (type A, B, C, D) were used. Detail eaxamination of wear scar was also performed using SEM micrographs. As a result, in the case of the spring of truncated wedge, severer wear occurs than the others. Protrusion part was found and larger in air at RT. It is thought that the difference in the wear volume and the protrusion is caused by the different wear mechanism corresponding to the different environment.

• Design & Manufacturing
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• 제16권4호
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• pp.46-51
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• 2022

The piercing process of creating holes in sheet metals for mechanical fastening generates high shear force. Real-time monitoring technology could predict tool damage and product defects due to this severe condition, but there are few applications for piercing high-strength aluminum. In this study, we analyzed the load signal to predict the punch's wear level during the process with a piezoelectric sensor installed piercing tool. Experiments were conducted on Al6061 T6 with a thickness of 3.0 mm using piercing punches whose edge angle was controlled by reflecting the wear level. The piercing load increases proportionally with the level of tool wear. For example, the maximum piercing load of the wear-shaped punch with the tip angle controlled at 6 degrees increased by 14% compared to the normal-shaped punch under the typical clearance of 6.7% of the aluminum piercing tool. In addition, the tool wear level increased compression during the down-stroke, which is caused by lateral force due to the decrease in the diameter of pierced holes. Our study showed the predictability of the wear level of punches through the recognition of changes in characteristic elements of the load signal during the piercing process.

• 패션비즈니스
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• 제3권1호
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• pp.65-80
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• 1999

In this study, the researcher studied the historical background and the traditional culture about dress and ornament of Yunnan Province of China. The Results of the study are as follows. 1. In the Past, Derung's dress was very simple due to the influence of various factors, such as geography and history. Men wore shorts and covered diagonally a piece of cloth from left shoulders to right armpits and tied up the two ends on chests. Women covered crisscross two pieces of cloth from both shoulders to knee. 2. Achang people's dress and adornment has its own unique characteristic. Generally, men wear Jackets with buttons down the front and black trousers. Unmarried men like to wear white turbans, while most of married men usually wear dark blue ones. Women usually wear tight-sleeve blouses with buttons down the front and skirts. Unmarried women wear the hair in braids coil them on the top of their heads. They wear short blouses and trousers. Married women wear their hair Into buns and like to entwine black or blue cloth into high trubans. They wear short blouses and knee-length straight skirts. Achang knife enjoys high reputation and has a long history and an exquisite workmanship. All the men like to wear it. 3. The dress and adornment of the Lahu nationality has both the characteristic of farming culture and the style of nomadic culture of early times. Men usually wear short shirts with round necks and buttons down the front, loose-legged trousers, turbans or dark blue cloth caps Women's dress and adornment can be categorized into two styles. One is black cloth gown with buttons diagonally on the right front and waist-length slits on both sides. The edges of fronts and cuffs are edged with Silver ornaments and lace. They also wear trousers. The other is short blouse with round neck and short opening on th right front, straight skirt and colourful leggings with embroidered patterns. 4. The Hani people, men and women, old and young, like black colour and are fond of wearing black clothes. Men usually wear shirts with buttons down the front and trousers, entwining their heads with black or white cloth. The elderly people wear calottes. Women wear cloth blouses, skirts and trousers or shorts. Slight differences exist in the clothing and adornments according to region, branch and age 5. Blang people's dyeing technique with an exquisite method has a long history. Men wear dark blue long sleeve shirts with round necks and buttons down the front or arranged diagonally on the front and loose-legged trousers. Elderly men wear big turbans wdress and adornment varies greatly in different regions. 6. The Lisu people culture of dress and adornment has some unique characteristics. The styles and colours of their dress and adornment differ slightly from place to place. In the Nujiang area, Women wear black velvet Jackets over blouses with buttons arranged diagonally on the right front and long pleated ramie skirts. Men usually wear wraparound ramie gowns, with center vent, made of fabrics alternated with white and black cross stripes. They also wear cloth waistbands and trohile youngsters keep their hair short. Women's users. In the Lushui area, the dress and adornment is similar to that in the Nujing region, but women wear aprons and trousers instead of skirts. 7. The Nu people dress and adornment is simple but elegant Women are proficient in ramie-weaving. Men usually wear gowns With overlapping necks, knee-length trousers and leggings. They like to wear their hair long and entwine dark blue or white turbans. Women wear black and red vests over blouses with buttons arranged diagonally on the right front and ankle-length skirts. They also wear their hair long, make it into braids, and entwine dark blue or colourful cloth turbans. 8. Pumi men usually wear ramie shirts With buttons arranged diagonally on the right front, loose trousers and white sheepskin vests. Some also wear overcoats made of "pulu". Women's dress and adornment varies in different areas. In the Lanping and Weixi regions, women wear white short blouses with buttons arranged diagonally on the front and dark brown embroidered vests. They also wear trousers and blue or black cloth turbans. In the Ninglang and Yongsheng regions, women wear hemmed blouses With buttons arranged diagonally on the right front and drape sheepskin capes. They also wear white pleated skirts and use broad colourful cloth as their waistbands.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.892-897
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• 2000

In this study, tap wear was analyzed not only to predict the tap life time but also to propose an improved tap design. Because rake angle and thread relief of tap are the significant factors in geometry of tap, these two factors were picked as the experiment variables. The experiment was conducted with six types of tap which have 6$^{\circ}$ , 8$^{\circ}$ and 12$^{\circ}$ of rake angles with 0,08mm and 0.14 mm of thread relief. From the measured cutting force, it could be known that cutting torque was low at the large the rake thread relief and tool life was long as rake angle became large. Eventually, tool life is longest when rake angle is 12$^{\circ}$ and the with 0.08mm thread relief. Aand the width of crater wear and that of flank wear were measured when a tapping torque was 20 [$kg_f$-mm] . Most of the measured values were above the width of tool wear[$V_B$=O.O3m], which means that tool life is over.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.241-244
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• 2004

In this paper wear ratio, hardness and microstructure were experimented for study of friction wear characteristic of automotive disk brake considering running distance. In this work.4 specimens were employed for test of the friction&wear tester as a function running distance. Despite the fact that brakes must operate under a variety of environmental conditions. most research has worked in laboratory with ideal condition.

• Tribology and Lubricants
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• 제17권3호
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• pp.221-227
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• 2001

The effect of silver particles on the sliding behavior of bearing steels was studied experimentally by using a ball-on-disk tribometer. Tests were performed in ambient air, dry air and vacuum. Disks of AISI 52100 were silver-coated by a thermal evaporation method, and the effects of silver particle transfer on friction were analyzed. In order to understand further the mechanism of silver particle transfer and its effect on friction and wear, pre-compressed silver particles were artificially introduced into the friction interface and the results were compared to those of silver-coated specimens. Results showed that the introduced silver particles produced transfer layers and resulted in low friction. It also showed that this low friction is closely related to the characteristic behavior of transfer layers. Shakedown occurred at the friction interface affected the friction and wear.

• 한국기계가공학회지
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• 제8권4호
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• pp.122-128
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• 2009

The purpose of this study is to show the friction and wear characteristics on the vapor deposited coating layers on the SCM415 steel. In this research, frictional wear characteristic of coating materials such as CrN, AlCrN, WC/C was investigated under room temperature, normal air pressure and nothing lubricating condition. Therefore this study carried out research on the friction coefficient, micro hardness(Hv), roughness, EPMA on the vapor deposited coating layers on the SCM415 steel.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.59-66
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• 2000

An experimental study on the effect of silver particles on the sliding behavior of bearing steels was performed by using a ball-on-disk tribometer. Tests were carried out in ambient air, dry and vacuum. Disks of AISI 52100 were silver-coaled by a thermal evaporation method, and the effects of silver particle transfer on friction were firstly analyzed. In order to understand further the mechanism of silver particles transfer and its effect on friction and wear, pre-compressed silver particles were artificially introduced into the friction interface and the results were compared to those of silver-coated specimens. Results showed that the introduced silver particles produced transfer layers and resulted in low friction. It also showed that this low friction is closely related to the characteristic behavior of transfer layers. Shakedown and rachetting occurred at the friction interface and affected the friction and wear.

• 한국의상디자인학회지
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• 제17권1호
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• pp.93-104
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• 2015

As interest grows in nursing-wear in accordance with dissemination of breast-feeding, a study on opening of nursing-wear is needed to enhance convenience of breast-feeding regardless of location. In this study, the items on nursing-wear were classified and each characteristic was analyzed. The types and characteristics of opening on nursing-wear were identified and the characteristics of nursing brassier closely related to the nursing-wear were also identified. Top 5 companies for the nursing-wear and nursing-brassier were selected by ranking top 5 in NAVER with the search word 'nursing-wear' and 'nursing-brassier'. 732 one-piece and top (t-shirt and blouse) which have the highest portion in the nursing-wear were selected as the subject. Based on the photo, product explanation on the internet and in-depth interview of designer, the types and characteristics of openings for each item were identified. 732 nursing-brassier were selected to study the types and openings in breast-feeding. The result is as follows. Firstly, the item of nursing-wear can be classified into top, one-piece, package of top and the bottom, and sleeveless. Top and one-piece have the highest production rate. Secondly, the types of the openings are either covering or opening types. There are vertical-slit and horizontal-slit in covering type, and vertical-zipper, horizontal-zipper, and button types in opening type, and overlap and pocket type for the rest. Thirdly, the commercially available nursing-brassier according to the opening manner can be classified into upper-opening, middle-opening, and overlap types. Most largely produced product is upper-opening type as it minimizes the exposure of the breast in breast-feeding. When producing the nursing-brassier, the measurement of the lower breast and cup size are considered.