• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1196-1201
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• 1993

Test of Caterpillar Challenger 65 tractor which has rubber tracks, and articulated four wheel drive tractor with dual wheels and a mechanical front wheel drive tractor were conducted on an unplowed and plouwed wheat stubble field. The following parameters were analyzed : tractive efficiency (ηv), net tractive coefficient ($\phi$n), slip ($\sigma$) , drawbar pull(Fv), drawbar power (Pv) and forward velocity(v). The maximum net tractive coefficient was established at the tractive efficiency of 0.60 on the unplowed wheat stubble field : for the Challenger 65 tractor 0.855 ; 4WD 0.624 and MFWD 0.534 and on the plowed wheat stubble field with the tractive efficiency of 0.40 for the Challenger 65 tractor 0.82 : 4WD 0.57 and for tractor MFWD 0.48.

• Elastomers and Composites
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• v.45 no.4
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• pp.280-285
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• 2010

The CIIR blends with SBR, NBR and BR were prepared with various mixing ratios. The mechanical and physical properties of these blends, such as frictional coefficient, abrasion resistance, compression set, and specific gravity, were measured. In the permanent compression set measurement, the blends at the composition of 75 wt% CIIR showed the highest value, which means the lowest resistance to deformation. As SBR, NBR and BR blends with CIIR, the coefficient of friction of the mixtures showed a tendency to decrease in arithmetic average. In the case of blending CIIR with BR in order to increase the friction force, the negative effect due to reduction in abrasion resistance was greater than the positive effect of the improvement of the traction force caused by increasing friction coefficient.

• Korean Journal of Acupuncture
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• v.29 no.3
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• pp.385-395
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• 2012

Objectives : Meridian sinew theory was introduced in Miraculous Pivot, Huangdi's Internal Classic, to explain in relation with locations of meridian sinews, causes, mechanisms, and treatment of diseases. The meridian sinews are understood to include muscles, tendons and ligaments, or muscles in the superficial body made up with muscles, ligaments, tendons, fascia etc. This theory shows the similarity or organic relationship between the meridian sinews and muscles. From the Hippocrates(460-385 BC) ages, traction therapy was used as a treatment method on muscular diseases such as low back pain, scoliosis, etc in western medicine. The effects of traction therapy, however, were unclear so that this study was purposed to illustrate the effectiveness of continuous traction therapy and to develop meridian sinews treatment. Methods : We made 2 hypotheses to explain the cause of scoliosis occurrence, muscles contraction and relaxation. As the hypothesis, we made the spinal model having 3 joints with wood and rubber bands. Each of the three joints in the spinal model represents the case of normal(NT; control), contraction(AT 1)and relaxation(AT 2) condition, and distance between the vertebrae joints was measured. Results : Under normal circumstance models, the normal type 1(NT 1; muscle relax state) and normal type 2(NT 2; muscle contract state) all joints were being towed equally. But in an unusual contracted situation, regardless of the relationship of joint area, contracted part of joint was not released. And in a relaxed situation, regardless of joint areas, released parts of joint were further released. These observation results mean that the effects of traction might be different from the purpose of traction therapy of Hippocrates. Conclusions : To explain the effect of traction therapy for scoliosis, the spinal cord model and scoliosis model were made. After vertebral bodies were pulled with different tensile forces, we compared the observed length of the each joints pulled. The results suggested that there were no effects of traction in objected parts with traction method from Hippocrates' design, continuous traction method. Moreover, it may worsen the symptom in worst case. Of course, our results are just the result of experimental models and clinical results may be different. More careful studies, therefore, are required.

• Elastomers and Composites
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• v.37 no.4
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• pp.217-223
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• 2002

Silica-filled rubber compounds show poor filler dispersion and slow cure characteristics compared to carbon black-filled ones. In general, a silica-filled rubber compound contains silane coupling agent (bis-(3-(triethoxysilyl)-propyl)-tetrasulfide, TESPT) and diphenylguanidine (DPG) to improve the filler dispersion and to make fast cure characteristics. Acrylonitrile-butadiene rubber (NBR) improves the filler dispersion in silica-filled styrene-butadiene rubber (SBR) compounds. In this study, effect of NBR on the properties of silica-filled SBR compounds was investigated. Properties of the compounds which contain NBR without DPG or with small amount of TESPT (Compound A) were compared with those of the compounds which contain TESPT and DPG without NBR (Compound B). Scorch time of Compound A is faster than those of Compound B. Modulus and tensile strength of Comound A are slightly lower than those of Compound B. Traction property of the Comound A is better than that of the Compound B. Addition of NBR leads to reduction of the used amount of TESPT and DPG.

• Elastomers and Composites
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• v.33 no.3
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• pp.201-209
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• 1998

Alumina powders used as a filler in rubber compounding was extracted from kaolin in $H_2SO_4$ solution employing conventional thermal and microwave energy resources. Maximum degrees of alumina extraction from kaolin were 72.8% at $80^{\circ}C$, 1M $H_2SO_4$, and 180min in the conventional thermal extraction process and were 99.0% at $90^{\circ}C$, 1M $H_2SO_4$,, and 60min in the microwave extraction one, respectively. The samples synthesized in both processes were analyzed by means of TG/DTA, XRD, SEM, Atomic Emission Spectroscopy, and BET method. Studies are presently under way to unravel the basic interaction mechanisms between microwave and alumina power for high rates of alumina extraction from kaolin in the microwave ex-traction process.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.135-140
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• 2003

Recently Light Rail Transit(LRT) systems, especially full automatic systems are strongly issued by many provinces and major cities due to it's own characteristic for economical, environmental and sufficient transportation capacity. But LRT design criteria should be modified according to Rolling Stock's properties. -size, arrangement of bogie and wheel, power of traction motor etc, This thesis suggest for basic standard design criteria of Rubber Tired Light Rail Transit system.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.310-316
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• 2020

Terpene-modified phenolic resins were used to improve the tires wet traction related to the driving safety and also rolling resistance related to fuel efficiency. In this work, alpha-pinene, beta pinene, and delta limonene resins, which constitute different basic structures of terpene-modified phenolic resins, were individually added to the tread compounds of tires and their physical properties were compared with those of the alkyl phenol resin compounds. Alkyl phenolic resins showed no significant difference in tangent delta from terpene-modified phenolic resins at 0 ℃, which is related to wet traction, but showed higher tangent delta at 80 ℃, which is related to rolling resistance, indicating smaller fuel efficiency improvement effects. Among the terpene-modified phenolic resins, beta pinene one showed improved wet traction and fuel efficiency compared to those of other resins. Delta limonene resin showed the best wet traction improvement effect, and alkyl phenolic resins showed relatively high tensile strength and abrasion property. All terpene-modified resins exhibited better rolling resistance than those of alkyl phenolic ones so that they can be said to have better fuel efficiency improvement effects and also to improve other properties compared to those of blanks. Terpene-modified phenolic resins could be used when mixing tire compounds referring to the properties of the phenolic resins revealed in this work, which could result in preparing compounds with improved wet traction and rolling resistance.

• Journal of Korean Society of Forest Science
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• v.84 no.2
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• pp.218-225
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• 1995

In this paper, a mechanical analysis model for steep-slope log-skidding operations of a rubber-tired tractor is discussed and the applicability of the model is investigated. The model largely consists of mathematical analysis models for log drag, dynamic vehicle weight distributions and soil-vehicle traction. For the case study, a theoretical data set for log skidding operations is used in investigating the effect of the factors influencing the results of mechanical analysis or the productivity of skidding operations. The analyses include 1) the effect of log choking methods on tangential log-skidding force, 2) the effects of the change in travel speed and log load on the required input power to the wheels and 3) the log skidding performance of a two-wheel drive compared with that of a four-wheel drive.

• Composites Research
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• v.36 no.3
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• pp.141-153
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• 2023

This review paper presents an introduction of contact mechanics and rubber friction theory for sliding friction of elastomer composites in contact with rough surfaces. Particularly, Klüppel & Heinrich theory considers the self-affine (or fractal) characteristic for rough surfaces to predict adhesion and hysteresis frictions of elastomers based on the contact mechanics of Greenwood & Williamson. Due to dynamic excitation process of elastomer composites while sliding in contact with multiscale surface roughness (or asperity), viscoelastic properties in a wide frequency range becomes major contributor to friction behaviors. A brief description and examples are provided to construct a viscoelastic master curve considering nonlinear viscoelasticity of elastomer composites. Finally, application of rubber friction theory to tire tread compounds in traction with road surfaces is discussed with several experimental and theoretical results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.266-269
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• 2006

Tire is in charge of a lot of function, which is supporting vehicle load, transferring traction and. brake, absorbing impact by road etc. As the silence of vehicle increase more important, the importance of tire noise is more raised. In recent, the study on reduction of tire noise is generally processed. Tire noise is divided in structure home noise and all borne noise. Tire tread properties have a lot of multiplicity. Rubber properties are caused by changing or tread hardness. That change Elastic Modulus and Loss Modulus, which is related by tire noise. In the study, we found that road noise is affected by tread hardness