• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.79-89
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• 1995

Rattle noise occurs at manual transmission as idling and driving of a automotive. It can be solved by torsional characteristics of a clutch disc. A clutch disc consist of a region of pre-damper and main-damper. Rattle noise is affected by pre-damper and main-damper equipped for a torsional spring and friction washer. Pre-damper range covers noise radiating from manual transmission when engine is idling and main-damper range covers noise when engine is driving. The aim of this reserch is to clear transmission rattle noise by way of torsional characteristics of a clutch disc. The experiment is carried out as idling and driving of a automobile equipped for 1.5L MPI engine, dry single-disc type clutch and manual transmission. In this study, the results show for a vibration of manual transmission as idling and driving can be cleared by a clutch disc of Pre-damper type.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.996-1001
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• 2006

Automatic washing machines have been improved and popularized steadily since the first electric washing machine was produced in the early 1900's. Appliance industry has tried to obtain the performance of washing machine with large capacity, high energy efficiency, low vibration and low noise levels. As the installation peace of a washer becomes closer to the living space, vibration and noise problems become more important challenges. In general, a washing machine has four legs to support its body. Four legs of the washing machine should be attached on a floor. If not so, it may cause severe vibration or walking in the spin-drying process. Unfortunately, the floor of an ordinary house is bumpy in general, and the consumers will not accept bolting washing machines to a foundation; moreover, sometimes they move the location of their washing machines to utility rooms or bath rooms or kitchens and don't care for leveling the legs exactly. In this study, we devise an auto-leg system that prevents the occurrence of abnormal vibration and walking of washing machines. It is simply composed of a spring and a friction damper. Some experiments are implemented to show the dynamic characteristics of the three-dimensional auto-legged washing machine model that is located on the even or uneven ground. A spring parameter is optimized to adjust the length of the auto-leg system automatically up to 10 mm irregularity, and the friction damper is designed to decrease a resonance induced by the spring of the auto-leg system. Some numerical results show that placing the proposed auto-leg system in a washing machine makes good performance with low vibration, as well as low noise, regardless of the unevenness of the floor.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.171-179
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• 1997

The high-tension bolted joints are clamped by the axial force which approaches the yielding strength. The introduced axial force is transmitted to the connection members pass through washer. The transferred load in connections is balanced to the compressive stress of plates, axial force in bolts and the external loads. In this mechanism, the compressive stress and slip load we dominated by the effective stiffness of bolted joints and plates. In general the effective stiffness is specified to product to the effective area and elasticity modulus in connections. In this reason, the conic projection formular which is assumed that the axial force in bolts is distributed to the cone shape and that region is related to the elastic deformation mechanism in connections, was proposed. But it conclude what kind of formula is justified. Therefore in this paper, the fatigue tests are performed to the high tension bolted joints and inspected to the phase on the friction face. And using the FEM and numerical method, it is analyzed and approximated to the compressive stress distribution and its region. Moreover, it is estimated to the effective area and to the relation the friction area to the effective compressive distribution region.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.5 s.153
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• pp.753-761
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• 2006

This paper suggests the optimal conditions for the laundry to prevent from the electrostatic charge by the evaluation of the electrostatic characteristics in the full process of washing and drying. Cotton, nylon, and polyester fabrics were used as test washing specimens. Detergent and softener were used under the standard washing cycle, and then the electrostatic characteristics of laundry were measured. The results showed that the moisture regain decreased and the electrostatic charge increased with the drying time. It was observed that the specimen fabrics were already dried up before the standard drying cycle was finished. Consequently, the excessive drying caused a generation of electrostatic charge due to the removal of the trace of moisture remaining and the excessive friction. Especially, the softener played an important role to prevent from a generation of electrostatic charge, whose insertion was more effective in the drying than in the rinsing process. It was also shown that the electrostatic charge could be decreased by drying the fabrics of one kind. On the other hand, for drying the mixed kinds of fabrics, the electrostatic charge increased remarkably. Therefore we suggest that the laundry be classified according to the kinds of fiber, and then be washed and dried before excessive drying to reduce electrostatic charge And further, a proper use of softener is effective to reduce electrostatic charge.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.1027-1033
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• 2011

A VCM sheet is a metal sheet on which PET/PVC is coated for outer panels of home appliances. The purpose of this study is to obtain methods for suppressing PET tearing that occurs during the press forming of the VCM sheet. In order to identity the factors that minimize PET tearing, an FE analysis was performed. The occurrence of PET tearing cannot be predicted using the conventional forming limit diagram. PET is torn by friction between a die and sheet, which is caused by the thickening of material at a die corner. To reduce the thickening of material, the blank shape was re-designed and the thickened material at a flange was removed by a trimming process. The results of the FE-analysis involving modified process parameters showed that the thickness of the product at a die corner is distributed within the clearance of drawing and flangeforming process. A forming experiment was conducted to verify the proposed process parameters. A good final product was obtained without PET tearing of the VCM sheet.