• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.4
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• pp.69-75
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• 1999

This study was performed to investigated the application of mixed resins for corrugated container board. The corrugated container board yields a sandwich structure in which a linerboard material is glued to a corrugated medium . Now, manufacturing corrugated container boards don't provide sufficient strength, and result in box failure during shipping . Therefore improvement of box strength is necessary . In this study, we intend to improve box strength by improving corrugated medium strength with mixed resins and to find the optimum treatment condition of this resins. First, we tried to mixed resins as Starch+CMC, Starch_Irea, CMC+Urea, Second, investigated to applicability of this resins for corrugated medium , and the third, measured tensile index, burst index, and edgewise compression index on liner, medium paper, and single faced corrugated container board. In this test results, we obtained that the improvement ratios of tensile index in liner and medium paper were approximately 80-185%, 60-118% , respectively. The respecting improvement ratios of edgewise compression index of single faced corrugated container board was approximately 91-124%, relatively. In addition, we concluded that optimum condition in mixing ratio was 1 :3 with CMC + Urea and the ap[plication amounts was 9% on materials. Fro manufacture of corrugated container board, optimum condition in mixing ratio was 1 : 3 with 5% CMC +Urea , because of considering to improvement of strength on cost.

• Journal of the Korean Society of Safety
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• v.16 no.1
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• pp.53-58
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• 2001

Constructions on the soft clay layer of low strength and high compression bring out many problems. Recent studies show that strength of the soft clay layer could be substantially improved by mixing quicklime. For the purpose, a series of uniaxial compression tests were performed, using quicklime, in order to analyze strength characteristics. The major test results are summarized following : When water content is 90%, the strength is observed to precipitously increase between 3～14 days, then, the extent slowly increase in relative terms. When water content is 130%, the strength is observed to precipitously increase up to 28 days. When the strength of water content 90% is compared to that of water content 130%, the initial strength of the former is higher than that of the latter. The analyses show that the improvement of soft clay layers can be realized by the mixture of both quicklime and sand, and by the mixture of quicklime only.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11b
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• pp.186-191
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• 1999

Results are shown on the preparation and characterization of homopolymer of 2-methacryloyloxyethyl isocyanate(MOI) ad copolymers of MOI with styrene synthesized by radical polymerization. The significant effectiveness of the polymers as additives for paper dry and wet strength was found. Dry strength can be increased by 75% and wet strength retention of sheets can reach 30% based on the increased dry strength and about 50% based on the dry strength of untreated sheet. Based on isocyanate group consumption, copolymers containing less isocyanate can give better effect than homopolymer in sheet wet strength improvement. Furthermore, the base paper containing a small amount of polyallylamine hydrochloride was used for polymer treatment and got higher wet strength improvement.

• Journal of Biosystems Engineering
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• v.41 no.1
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• pp.1-11
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• 2016

Purpose: The gear strength of a new mechanical transmission designed to increase the loading weight of small 4.8 kW tracked agricultural transporters was analyzed. Design improvements to increase the gear strength and reduce the gear weight were proposed after examining the parameters. Methods: Sixteen operators from three regions were surveyed to obtain the usage profile of small 4.8 kW transporters. Gear strength was evaluated by calculating contact stress and tooth root stress using commercial software following ISO 6336. Results: From the strength calculation for each gear pair, contact stress smaller than tooth root stresses were produced in all gear pairs. The safety factors in most cases exceeded 1.0, except in the case of gear pair II in group II. The design life of the transporter using gear pair II in group II was 42% under harsh conditions-thus, this design life needs improvement. A robust design was proposed by examining the relevant parameters (face width and profile shift coefficient) to increase the design life of the transporter. In addition, a lightweight design for gear pair I in group II that was considered overdesigned was proposed by examining the face width to reduce the weight of the drive gear by 42% and that of the driven gear by 30%. Conclusions: The Safety factor for the design life was examined through a gear strength analysis. After examining the relevant parameters, conditions for strength improvement were proposed to increase design life or adjust overdesigned gear. However, load conditions differ depending on the working conditions or user's preferences; therefore, it is necessary to conduct further studies in various regions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.135-141
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• 2013

In this study, to improve the early-age compressive strength of mortar, the compressive strength tests of mortar mixed smart BFS powder added powder of rapid setting additives milled by processing, using functional grinding aid, the power-typed rapid setting cement clinker developed by sintering industrial waste and by-products with much CaO-$SiO_2-Al_2O_3$ to cement were performed. From the tests, the followings are found that (1) for BFS early-age strength improvement test (Series I): early-age strength improvement of BFS mixed rapid setting additive milled after adding functional grinding aid, when the clinker is milled, is superior and (2) for OPC early-age strength improvement test (Series II): case of additive mixed rapid setting powder typed activator milled after adding functional grinding aid to Clinker-C showed the higher compressive strength.

• Geotechnical Engineering
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• v.12 no.2
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• pp.115-132
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• 1996

Several soil improvement methods are applied to stabilize soft ground. But, their improvement effects are known to be reduced in view of strength and durability under poor conditions such as marine clay and the ground with the flow of groundwater. The soil improvement method is generally classified as mixing(high pressure) type and injection type, and in this study, for successflll'applications of gelling methods, first in case that mixing method with cement is applied to marine clay, the causes of strength inferiority of treated soil are analyzed, and the effectiveness of improvement is studied, second in case that injection method with water-glass chemical grouts is applied to the ground with the flow of groundwater, soil improvement effects and durability of grouted soil are studied.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.263-270
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• 1999

In country, for 2002 World-cup the peak is to construct soccer playground. the stabilizing method by additives is mainly applied of permanent improvement for bearing capacity of structure foundation and for strength, durability and transformation of road pavement layer except for construction machine's trafficability and bearing capacity. This study is on soft ground improvement of $\bigcirc$$\bigcirc$ world-cup stadium field. construction field constitutes of very various layers and after construction the lawn grass should be planted on the surface of the earth and in addition, chemical effects should be limited from improved ground layer. Mixing soft clay in field with three domestic representative additives, it evaluated the unconfined compression strength. In the results, after curing during 28 days the objective strength has been obtained on about 5% combination ratio.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.263-264
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• 2012

The purpose of present study is to examine the long-term strength improvement of hardener-free epoxy-modified mortars with steam curing. As a result, strength improvement of hardener-free epoxy-modified mortars is markedly improved with increasing of air-dry curing period. This is improved by markedly increase the degree of hardening of the hardener-free epoxy resin in the epoxy-modified mortars with additional air-dry curing period.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.4
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• pp.14-20
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• 2007

The effects of blending starches with different gelatinization temperatures on the development of ply-bond strength were systematically investigated using a three component mixture design technique. Oxidized corn starches with different gelatinization temperatures were blended with natural corn starch and sprayed for plybonding. Optimum blend ratio for maximizing plybond strength improvement for the starch blends was 40% of natural starch, 27% of oxidized starch with low gelatinization temperature and 33% of oxidized starch with high gelatinization temperature. Starch granules with the lowest gelatinization temperature gelatinizes at the lowest temperature, while the natural corn starch gelatinizes at later stage of drying. The improvement of plybond strength with starch blends were verified on machine trial as well. Plybond strength improvement obtained from the machine trial was lower than that achievable with handsheets, which was attributed to the lower internal bond strength of the linerboards made from recycled fibers.

• Journal of Life Science
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• v.19 no.12
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• pp.1821-1828
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• 2009

The purpose of this research was to investigate how the plyometric training and weight training program, applied in the field for exercise performance of throwing players, influenced improvement of athletic abilities, including agility, maximum muscular power, and strength. After implementing plyometric training and weight training to 21 high school throwing players for 10 weeks, we designed the next step. The 21 subjects were divided into two groups - women's group and men's group. All subjects were tested to determine agility using sidestep, burpee test, reaction time, lower body power and strength using standing long jump, standing jump, 30 m running, squats and leg presses. Additionally, isokinetic strength was measured using Cybex isokinetic dynamometer. The results showed that both groups demonstrated improvement in the standing long jump, standing jump and 30 m running after training. Particularly, the women's group indicated better improvement. Second, women's groups showed higher improvement in the sidestep and burpee test. However, in the reaction time test, the men's group indicated better improvement. Third, both groups showed better improvement in squats and leg presses after training. Particularly, the women's group indicated better improvement. Fourth, in the left and right side extension torque and flexion torque at a velocity of $60^{\circ}$/sec, both groups showed better improvement after training. In the left side extension peak torque, the men's group showed higher improvement, but the women's group showed higher improvement in the left side flexion and extension peak torque. Fifth, both groups showed better improvement in bench pressing and back strength after training. Particularly, the women's group indicated higher improvement.