• Journal of the Korean Society of Safety
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• v.19 no.1
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• pp.12-17
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• 2004

By using an experimental approach recently developed to determine the torque-tension relationship for bearing frictional characteristics of several typical bolted joints were studied. The experimental approach allows the direct determination of the bearing friction between the nut and its bearing surface. Detailed friction studies were made on the influences of the size and shape of the hole, the use of a slot in a bolted joint, contact area and position, and other factors such as turning speed, coating, and the use of wax on the bearing surface. The contact area and position of the washer have a marginal effect on the bearing friction. The organic coating on the nuts reduces the bearing friction significantly. Nuts with organic coating over a washer with zinc finish provide the smallest and the most consistent bearing friction. The results from the experimental investigation will be helpful for the better design of bolted joints bearing friction. The results from the experimental investigation Will be helpful for the better design of bolted joints.

• Journal of the Korean institute of surface engineering
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• v.36 no.6
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• pp.491-499
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• 2003

Copper-based leadframe sheets were oxidized in a hot alkaline solution to form brown-oxide layer on the surface and molded with epoxy molding compound (EMC). The brown-oxide-coated leadframe/EMC joints were machined to form sandwiched double-cantilever beam (SDCB) specimens and sandwiched Brazil-nut (SBN) specimens for the purpose of measuring the fracture toughness of leadframe/EMC interfaces. The SDCB and the SBN specimens were designed to measure the fracture toughness of the leadframe/EMC interfaces under nearly mode-I loading and mixed-mode (mode I ＋ mode II) loading conditions, respectively. Fracture surfaces were analyzed by various equipment such as glancing-angle XRD, SEM, AES, EDS and AFM to elucidate failure path. Results showed that failure occurred irregularly in the SDCB specimens, and oxidation time of 2 minutes divided the types of irregular failures into two classes. The failure in the SBN specimens was quite different from that in the SDCB specimens. The failure path in the SBN specimens was not dependent on the phase angle as well as the distance from tips of pre-cracks.

• Resources Recycling
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• v.9 no.6
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• pp.9-14
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• 2000

Comparing the adsorption characteristics of coconut shell activated carbon (CSAC) and waste paint activated carbon (WPAC), Freundlich adsorption isotherms of alkylbenzene sulfonate (ABS) obtained from the secondary treatment water of H company and effluent of D company were estimated q=23.12 $C^{0.42}$ , q=18.32 $C^{0.38}$ with WPAC and $q=36.76C^{1.37}$ /, q=26.67 $C^{0.42}$ with CSAC respectively. In the case of H company, breakthrough time of the ABS using CSAC by continuous experiment was estimated 680 minute md that of WPAC was 610 minute. In the case of D company effluent, CSAC was estimated 720 minute, and that of WPAC was estimated 640 minute to reach the breakthrough. From the above results, it is possible to replace the coco-nut shell activated carbon with wasted paint activated carbon.

• Elastomers and Composites
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• v.54 no.2
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• pp.135-141
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• 2019

Polyphenylene sulfide (PPS) was filled with glass fiber (GF), aramid fiber (AF), and solid lubricants to improve the mechanical properties and wear resistance. The addition of GF effectively enhanced the tensile strength, flexural modulus, and impact strength of PPS, while solid lubricants such as polytetrafluoroethylene (PTFE), molybdenum disulfide ($MoS_2$), and tungsten disulfide ($WS_2$) lowered the friction coefficients of the composites to below 0.3. The ball nut and motor pulley of the electric power steering (EPS) were manufactured using the PPS composites, and feasibility was ascertained thereafter by conducting the durability test. The composites filled with GF and AF showed high mechanical strength, but slip occurred at the interface between the pulley and belt while testing above $50^{\circ}C$. When small amounts of lubricants were added, the slip was no longer detected because of the suppression of friction heat. It is realized that the low friction as well as high mechanical properties is important to ensure the reliability of plastic pulleys.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.961-968
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• 2022

Hydrogen embrittlement leads to the damages in bolts, nut, especially, high pressure valves, in the semiconductor facilities, hydrogen vehicles, hydrogen stations and so on. Monel material has higher strength than SUS material. Therefore, even though Monel material with special alloy is usually used to prevent the hydrogen embrittlement, it needs powerful drawing system to manufacture the rectangular or hexagonal bar using circular bar. The purpose of this study is to investigate the characteristics of plastic deformation of Monel material and 2 rollers of rolling unit in plastic limit through numerical analysis. As the results, it was predicted that, based on mean stress, as the rolling step was increased, the rolling force of rolling unit was decreased. In addition, the heat treatment for Monel material was needed because of residual stress due to plastic deformation. As for rollers, the roller was safe about 1.86 times compared with that of ultimate strength. In this study, as the roller 2 showed larger stress than roller 1, thus, roller 2 should be designed carefully to guarantee the safety. Further it was confirmed that the reaction force of roller could be helpful in bearing design.

• The Korean Journal of Food And Nutrition
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• v.36 no.1
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• pp.69-85
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• 2023

Sustainable and healthy diet is a challenge in recent world. Despite the global depletion of water resources, Korea has no system for controlling its water footprint. This study established the water footprint tables of Korean food using the Water Footprint Network databases, and applied them into two meal plans for 19~64 year-old adults recommended in the Dietary Reference Intakes for Koreans 2020. Nut, oil, and meat's water footprints were higher and those of fruit and vegetable were lower. Sesame oil had the highest water footprint of 21,793 L/kg and pineapple had the lowest domestic water footprint of 102 L/kg. Water footprint of one serving size of beef was 925 L, that of chicken was 260 L, and those of soybean were 43 L in global and 81 L in domestic. The water footprint of the recommended 2,400 kcal meal plan was 2,882 L, and that of 1,900 kcal meal plan was 1,915 L. The water resources can be saved by choosing food with lower water footprint. The results of this study can be used in the further researches for more sustainable and healthier Korean diet.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.3
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• pp.250-255
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• 1983

Newly manufactured compound fertilizers for chestnut trees developed by Chosun Fertilizer Inc. were tested to evaluate their effectiveness. An experiment was carried out in chestnut farm with 4 years old Eungi Var. from 1981 to 1982. The results obtained are as follows: 1. The growth of chestnut trees was generally good in plots of compound fertilizer contained boron (B C F). 2. The number of ripened strobiles was significantly increased by reducing the ratio of dropped strobiles in plot of B C F. 3. The yield of chestnut by B C F was markedly increased, 6 times more than that of compound fertilizer without boron. 4. Boron content in soil and plant by application of B C F was relatively high, resulting in high production of chestnut. 5. B C F was effective in chestnut orchard to increase nut production markedly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.1
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• pp.41-51
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• 2016

Friction generated from balls and grooves incurs temperature rise in the ballscrew system. Thermal deformation due to the heat degrades positioning accuracy of the feed drive system. To compensate for the thermal error, accurate prediction of the temperature distribution is required first. In this paper, to predict the temperature distribution according to the rotational speed, solid and hollow cylinders are applied for analysis of the ballscrew shaft and nut, respectively. Boundary conditions such as the convective heat transfer coefficient, friction torque, and thermal contact conductance (TCC) between balls and grooves are formulated according to operating and fabrication conditions of the ballscrew. Explicit FDM (finite difference method) is studied for development of a temperature prediction simulator. Its effectiveness is verified through numerical analysis.

• Journal of Korean Society of Forest Science
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• v.74 no.1
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• pp.82-87
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• 1986

Noticed that large number of the Korean white pine (Pinus koraiensis S. et Z.) has lost its typical excurrent tree from by removal of apical shoot in the process of cone harvesting, the investigation and analysis for the species were made on the basis of the relationship among DBH, total height, merchantable height, and merchantable volume, compared with normally grown Japanese larch (Larix leptolepis Gordon). One hundred sample trees for each species were selected in the same aged stands for the study. Results have indicated that the pine has shown abnormal height growth pattern mainly by the disturbance of external artificial force. The pine's forked and/or crooked stems by the reason lave led the result of less merchantable volume in the same DBH classes. Consequently, the pine would have undesirable tree form in terms of timber production, unless free from apical shoot disturbances. Considered to the merit of the Korean white pine that can produce timber and pine nuts, management alternatives for the pine stand were suggested to achieve maximum rate of return for the silvicultural investment.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4725-4732
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• 2012

Aim: The incidence of stomach cancer in Mizoram is highest in India. We have conducted a population based matched case-control study to identify environmental and genetic risk factors in this geographical area. Methods: A total of 102 histologically confirmed stomach cancer cases and 204 matched healthy population controls were recruited. GSTM1 and GSTT1 genotypes were determined by PCR and H. pylori infections were determined by ELISA. Results: Tobacco-smoking was found to be an important risk factor for high incidence of stomach cancer in Mizoram. Meiziol (local cigarette) smoking was a more important risk factor than other tobacco related habits. Cigarette, tuibur (tobacco smoke infused water) and betel nut consumption synergistically increased the risk of stomach cancer. Polymorphisms of GSTM1 and GSTT1 genes were not found to be directly associated with stomach cancer in Mizoram. However, they appeared to be effect modifiers. Persons habituated with tobacco smoking and/or tuibur habit had increased risk of stomach cancer if they carried the GSTM1 null genotype and GSTT1 non-null genotype. Conclusion: Tobacco smoking, especially meiziol is the important risk factor for stomach cancer in Mizoram. GSTM1 and GSTT1 genes modify the effect of tobacco habits. This study is a first step in understanding the epidemiology of stomach cancer in Mizoram, India.