• Tribology and Lubricants
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• v.39 no.6
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• pp.250-255
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• 2023

This study applies various surface patterns to minimize material loss in construction equipment that is subject to severe wear due to sand, such as the wear-resistant steel plates of dump trucks or the teeth of excavators. The relationship between surface morphology and wear behavior is investigated using PLA+ polymer to observe the effect of the surface pattern. Five types of samples - smooth, concave, convex, wavy concave, and wavy convex designs - are created using a 3D printer. A wear experiment is conducted for a duration of 3 h using 6.5 kg of abrasive particles. The mass loss of the samples after the experiment is measured to assess the extent of wear. Additionally, the surface morphology of the samples before and after the experiment is analyzed using SEM and confocal microscopy. The study results reveal that the smooth design exhibits the highest wear loss, whereas the concave and wavy concave designs show relatively lower wear loss. The convex and wavy convex designs exhibit varying contact areas with the abrasive particles depending on the surface pattern, resulting in different levels of wear. Furthermore, a comparison between the experimental results and DEM simulations confirms the observed wear trends. This study reveals the relationship between wear damage according to surface pattern shape and is expected to be of substantial help in the analysis of wear and tear on agricultural and heavy equipment.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1132-1133
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• 2006

Metal-bonded diamond impregnated tools are being increasingly used in the processing of stone and ceramics, road repair, petroleum exploration, etc. Although the main tool wear mechanisms have been identified, the scientific background is inadequate and fundamental research has to be carried out to better understand the tool field behaviour. This work addresses the complex issues of modelling abrasive wear of the metallic matrix under laboratory conditions. The generated data indicates that the matrix wear resistance can be assessed in a simple manner; whereas tests carried out on diamond impregnated specimens may aid prediction of the tool life in abrasive applications.

• Journal of Veterinary Clinics
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• v.10 no.2
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• pp.203-214
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• 1993

With the use of a rat surgical model, the ability of carboxymethylcellulose and ibuprofen in the reduction of abdominal adhesion was examined. Seventy seven female rats were randomly divided into 7 groups : (1) control, (2) 2% CMC, (3) 3% CMC, (4) ibuprofen 25mg, (5) ibuprofen 50mg, (6) combination of ibuprofen 25mg and 2% CMC and(7) combination of ibuprofen 50mg and 3%, CMC. Following induction of abrasion injuries on ileum, colon and both uterine horns with a surgical blads, the rats in groups (2), (6) were infused with 2% CMC solution singly or in combined Infection of 25 mg/kg of ibuprofen for three consecutive days, the rats In groups (3), (7) were infused with 3% CMC solution singly or In combined Injection of 50mg/kg of ibuprofen for three consecutive days. The rats in groups (4), (5) were injected only with 25 mg or 50 mg/kg of ibuprofen for three consecutive days. After 10 days the abdominal cavities were opened and the appearance of formed adhesion were graded. The changes of body weight, CBC and blood chemicals were also evaluated at 3, 6 and 10 days after operation. In ileum, the rats in the groups (2), (6) and (7) showed less adhesion formation. In colon, there were significant differences(p<0.05) in adhesion formation in all treated groups as compared to control. In both uterine horns, there were significant decrease(p<0.05) of adhesion formation in groups(2), (6) and (7) in comparison with other groups. The increasing rate of body weight was evident in group (3) and fibrinogen concentrations at 6 and 10 days revealed significant decrease (p<0.01) in group (7), whereas there was no consistent change in CBC and blood chemicals. Therefore, it can be sugested that the infusion of 2% CMC solution with or without the injection of 25 mg/kg of ibuprofen and 3% CMC solution with the injection of 50 mg/kg of ibuprofen are effective and safe following abdominal surgery,

• Journal of Preventive Medicine and Public Health
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• v.28 no.3 s.51
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• pp.551-562
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• 1995

To assess the status of safety accidents, authors reviewed and analysed the records of safety accidents of a welding material manufacturing factory at Pohang city from January 1989 to December 1993. The results are; 1. The total incidence of safety accidents was 295 spells for five years. 2. Average age of workers with accident was 35.7 years. Average duration of employment was 6.2 years and the duration of employment increased as the year increased. 3. There was no statistical significance on season, month, weekday and time by year in the incidence of safety accidents. The most frequent part of body injured was upper extremities and the most frequent type of injury was abrasion. 4. Mean admission rate of safety accidents was 12.6% and the ratio of treated spells as occupational injury was 7.8%. 5. The most frequent cause of injury was worker's mistake and the most frequent action for the prevention of further accidents was safety education. 6. The incidence rate of safety accidents on 1993 was 116.2 spells per 1,000 persons. Above results suggest that to prevent safety accidents, safety education should be done continuously, the environmental and human factors were controlled and more exact reporting system of safety accidents was needed.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.180-191
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• 2013

The purpose of this research was to find an optimal quarrying for marble by analyzing the applicability and the work efficiency of a chain saw machine newly introduced in the underground Baekwoon mine. From the test results of the physical properties of Baekwoon marble, which affects the efficiency of rock cutting, it was found to have similar physical characteristics as the ones which are now being produced in the other areas in Korea. And especially it shows isotropic property, which can be thought to be advantageous as a dimensional stone. To check the long-term quality of the marble as a stone material, several tests such as corrosion resistance test and abrasion test were carried out. It was found to be vulnerable to acid rain with decrease of weight and seismic wave velocity after applying artificial rain at pH 5.6 for 50 times. The percentage of wear from abrasion test was 22.67%. The working time and cutting speed of the chain saw machine were recorded and analyzed during the test-run at the quarry. The overall work cycle was assorted into 9 unit operations and the operating time per each unit was drawn. The operating times for the two cutting patterns, which could be possibly applicable to the work site, were compared. The results indicated that the pattern B, that the cutting sequence was set to minimize the movement of the machine, showed 6% less working hours than the pattern A, which first cuts the outer boundary. With cutting pattern analysis, the ore body in the Baekwoon mine was 3 dimensionally modeled and a quarrying plan considering the existing conditions of the marble was suggested.

• Journal of Veterinary Clinics
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• v.13 no.2
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• pp.144-148
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• 1996

The effectiveness of sodium carboxymethylcellulose (SCMC) and deztran in the prevention of adhesion formation on the uterus and embryo collection in rabbits was elucidated. Following induction of adhesion on uterus and uterine horns by abrasion and retrograde flushing of embryos in gonadotropins primed rabbits, the solutions of saline (for control), 1% SCMC, 10% dextran and a synthetic solution of 1% SCNC and 10% dextran in saline were infused in the abdominal cavity at the dose of 5 ml/kg of body weight. The average percentage of adhesion was 11.1, 28.6, 41.7 and 73.3% in the rabbits infused with the synthetic, 1% SCMC, 10% dextran and saline solutions, respectively. The synthetic solution was more effective than other solutions in the rabbits. The average number and recovery rate of embryos were significantly (P<0.01) higher in the synthetic solution group than 1% SCMC, 10% dextran or saline solution groups. Among the collected embryos in the groups, the distribution of the normal embryos was higher in the synthetic solution group (99%) and the 10% dextran solution group (95.7%) than the 1% SCMC solution group (78.4%) and saline (66.2%). Theretore, a synthetic solution which is combined with 1% SCMC and 10% deztran in saline can be effectively used for the prevention of adhesion formation after uterine surgery and embryo collection.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.144-151
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• 2014

Recently, according to the advances of vehicle manufacturing technology and the fuel-efficient vehicles, the weight of the vehicle body has been reduced and quietness of the vehicle has been increased. So that, as the emotional qualities of cars, such as NVH, are emphasized in recent years. Also required to be established of the effective measure for brake Judder. The Judder was caused by the increase in DTV by the uneven thermo metamorphosis of brake disc and the partial abrasion of disc. In this study, the disc aggression by friction materials was confirmed and the improving methods of friction materials in connection with the abrasive characteristics reviewed of $ZrSiO_4$ each particle size(under $3{\mu}m$, $5{\sim}10{\mu}m$ and over $15{\mu}m$). In addition, the study is institute make use of limit for $ZrSiO_4$ raw-material particle size and vol% in friction materials. At the result, the optimum size of $ZrSiO_4$ particles was confirmed about 5 to $10{\mu}m$.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.170-187
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• 2020

Dolmens bearing the burial layout and stone coffin tombs of the late Bronze Age were excavated from Samdeok-ri, Goseong, Gyeonsangnsamdo, and grave items such as red-burnished pottery, arrowheads, and stone swords were also discovered. In the case of the red-burnished pottery that was found, it retains a pigment layer with a thickness of about 50 to 160㎛, but with most of the other items, exfoliation and peeling-off of pigment layers can be observed on the surface. The raw materials of the red-burnished pottery contained moderately sorted minerals such as quartz, feldspar, and hornblende, and partly opaque iron oxide minerals were also identified. In particular, the raw materials of the red-burnished pottery from stone coffin tomb #6 were different from those of the other pottery, containing large amounts of hornblende and feldspar. The pottery's red pigment was identified as hematite and showed similar mineral content of raw materials such as fine grained quartz, feldspar, and hornblende. The firing temperature is estimated to have been approximately 900℃, based on their mineral phase. The possibility exists that the raw materials had been collected from the Samdeok-ri area, because diorite and granite diorite with dominant feldspar and hornblende have been identified within 3km of that area. During the pottery manufacturing process, it is estimated that the pigment was painted on the entire surface of the red-burnished pottery after it had been molded and then finished using the abrasion technique. In other words, the red-burnished pottery was made by the process of vessel forming - semi drying - coloring - polishing. The surface and cross-section of the pottery appears differently depending on the concentration of the pigment and the coloring method used after vessels were formed. Most of the excavated pottery features a distinct boundary between pigment and body fabric. However, in the case of pottery in which fine-grained pigments penetrate the body fabric so that layers cannot be distinguished, there is the possibility that the fine-grained pigment layer was applied at a low concentration or immediately after vessel forming. Many cracks can be seen on the surface pigments in thickly painted pottery items, and in many cases, only a small portion of the pigment layers remain due to surface exfoliation and abrasion in the burial environment. It is reported that pottery items may be more easily damaged by abrasion if coated with pigment and polished, so it is believed that the red-burnished pottery of the Samdeok-ri site suffered from weathering in the burial environment. This damage was more extensive in the potsherds that were scattered outside the tomb.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.120-132
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• 1998

This stusy was to investigate the marginal fitness of porcelain-fused-to- metal crown after succesive firing cycle. Main variables were the degree of marginal curvature of labiocervical margin and the type of alloy. The exaggerated marginal curvature(EMC) was created by additional reduction at the faciocervical wall of the normallized marginal curvature (NMC)-typed ivorine tooth by using milling machine. The difference in the shape was the mid facial margin was placed 2mm apical to cemento- enamel junction in labial surface. Three types of alloy were high noble, noble, and base metal alloy. Test specimens were divided into 8 groups and each group had 8 specimens. Sixty four ceramometal crowns were made totally. Measurement stages were following degassing, opaquing. body porcelain firing, and glazing, and measuring sites were 4. (midmesial, midfacial, middistal, and midlingual). Digital, travelling measuring microscope (0.5 um precision, Olympus. Japan) was used under ${\times}250$ magnification. Within the limitation of this investigation, it was concluded as belows: 1. The pattern of marginal distortion was varied. Degassing stage was not a specific, causative stage that induce most of total marginal distortion during whole procedure fabricating a ceramometal crown. Body firing stage induced discrepancy relatively more than other firing stages. 2. The specimens that were Ni-based alloy and had EMC were distorted persistently following successive fabricating procedures. But marginal openings were decreased after glazing. 3. The release of metal grinding-induced stress was presumed as a cause that induce marginal distortion. 4. The amount of discrepancies of the labial and lingual margins were greater than that of the mesial and distal margin in the specimen that had EMC. 5. Silver-plated die was not enough to resist abrasion during repeated seating of metal copings on the die-holding device.

• Journal of Fashion Business
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• v.16 no.6
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• pp.21-35
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• 2012

In consideration of the injuries and deaths occurring at manufacturing sites due to the use of inappropriate work clothes or safety devices, this study aims to categorize manufacturing work processes to develop functional work clothes for heavy industries including the automobile, machine and shipbuilding industries in South Korea. Defining the features of the work environments and work postures of these industries provided for a categorization of the work processes which would enable the development of suitable work clothes for each work process' category. The results of the study based on a questionnaire survey are as follows: Work process category 1, including steel panel pressing and auto body assembly, final inspection (in automobile) and inspection (in machine), requires work clothes with upper body and arm mobility and performance to protect from the toxic fume factor. Work process category 2, consisting of welding (in automobile), cutting-and-forming (in machine) and attachment-and-construction (in shipbuilding), requires clothing elasticity, durability and heat and fire resistance. Work process category 3 comprising welding and grinding in the machine and shipbuilding industries, requires work clothes' tear resistance and elasticity, particularly for lateral bending mobility, and work clothes' sleeves' and pants' hemlines with sealed designs to defend against iron filing penetration, as well as incombustible and heat-resistant material performance. Finally, work process category 4, including painting in machine and shipbuilding, requires work clothes with waterproofing, air permeability, thermal performance, elasticity, durability and abrasion resistance.