• Journal of the Korea Fashion and Costume Design Association
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• v.10 no.1
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• pp.99-116
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• 2008

This study reviewed pertinent literature and examined relics of manggon(a headband worn to hold a man's topknot hair in place), donggot(a topknot pin), and chigwan(a topknot cover). Before the modernized short hair style, wearing a gat was an important custom. Therefore, manggon, which was used to hold a man's hair in place under the gat, was considered an essential part of the man's official dress code. Donggot is a pin that held the topknot hair in place. It was a must have for a married man, like the binyeo, a lod-like hairpin, for a married woman. Unlike gwanja, it had nothing to do with official rank, but materials were of a variety of materials, including jade and gold. The structure of the donggot was studied in three parts-head, neck and body. Major forms for the head include the mushroom, bean and ball. Bullet and half-cut bullet forms were also found. Forms for the neck include straight-neck and curved-neck. A neck with a belt around a double chin was also found. Forms for the body include the tetrahedron, octahedron and cylinder. The most popular form for silver and white bronze donggot heads was the mushroom, followed by bean and pile forms. Chigwan is also called chipogwan, chichoal, choalgyesogwan, noingwan and sangtugwan. In poetry it was called chichoal, and it used to be called taegogwan in the past as well. Chigwan was so small that it managed to hold a topknot. According to confucian custom in the Joseon period, by wearing chigwan, men didn't display their bare topknot even when they didn't dress up. When they went out, they wore another official hat over the chigwan.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.4 s.109
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• pp.319-328
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• 2006

This paper presents a method for analysis of the mechanical behavior of a crankshaft in a four-cylinder internal combustion engine. The purpose of the analysis was to study the characteristics of the shaft in which the pin and arm parts were assumed to have a uniform section in order to simplify the modal analysis. The results of natural frequency transfer function and mode shape were compared with those obtained by experimental work. The results obtained from the comparison showed a good agreement with each other and consequently verified the analysis model. Furthermore, a prediction of crankshaft characteristics under the firing condition, by using the model, was performed. This study describes a new method for analyzing the dynamic behavior of crankshaft vibrations in the frequency domain based on the initial firing stages. The new method used RMS values to calculate the energy at each bearing journal and counter weight shape modification under the operating conditions.

• Tribology and Lubricants
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• v.34 no.3
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• pp.93-107
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• 2018

The purpose of Part I of this study is to find the potential region of wear scarring on engine journal bearings operating at a constant angular crank shaft velocity under firing conditions. To do this, we calculate the applied loads and eccentricities of a big-end journal bearing installed on a four-stroke and four-cylinder engine at every crank angle. Then, we find potential wear regions, such as a minimum oil film thickness, at every crank angle below most oil film thickness scarring wear (MOFTSW) obtained based on the concept of the centerline average surface roughness. Thus, the wear region is defined as a set of each film thickness below the MOFTSW at every crank angle. In this region, the wear volume changes according to the wear depth and wear angle, depending on the minimum oil film thickness at every crank angle. The total wear volume is the summation during one cycle. Graphical views of the region in the two-dimensional coordinates show the crank angle and bearing angle along the journal center path, indicating the position of the minimum oil film thickness. The results of wear analysis show that the possible wear region is located at a few tens of angles behind the upper center of a big-end bearing at maximum power rpm.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1993.04a
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• pp.39-53
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• 1993

The minimum oil film thickness(MOFT) in the connecting-rod bering of a 1.5 liter, L-4, gasoline engine is measured up to 5500 rpm and calculated to study the dynamically loaded engine bearing. Short bearing approximation and Mobility method are used for theoretical analysis of oil film charactrtistics. And cylinder pressure, crank-pin surface temperature and bearing tenp ture are measured as the input data of theoretical analysis. The MOFT are measured by the total capacitance method(TCM). To improve the reliability of the test results, a reasonable detmuuination method of bearing clearance is introduced and used, and the effects of cavitation and aeration on the test results are neglected. The crankshaft is grounded by means of a slip ring. A scissor type linkage system was developed to measure the MOFT and bearing temperature. The effects of engine speed, load and oil viscosity on the measured and calculated minimum oil film thicknesses are investigated at 1500 to 5500 rpm. From the comparison between the measured and calculated MOFT, it is found that a qualitative similarity exists between them, but in all cases, the measured MOFT are smaller than those calculated.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.355-361
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• 2004

Ceramic femoral heads in the total hip replacement have been developed to reduce the polyethylene liner wear, Alumina and zirconia (3Y-TZP) having the excellent tribological properties are coupled against acetabular cups of polyethylene and are used in clinical application worldwide. However, alumina has a risk of catastrophic failure, and zirconia has the low temperature degradation in spite of enhanced fracture toughness. Recently, novel zirconia/alumina composite is very attractive due to the low temperature degradation (LTD)-free character and high fracture toughness. In the present study, we focus on the wear of ceramic on ceramic, which are able to be used as femoral heads and acetabular cups. Therefore, LTD-free zirconia/alumina composites with three compositions are made in a form of disk and cylinder, and the wear of the composites is performed on pin-on-disk type wear tester. The wear is conducted with or without lubricant. All the composites fabricated with the different composition show the good wear resistance.

• Journal of Biosystems Engineering
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• v.27 no.3
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• pp.203-210
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• 2002

In this study, the leveling control system for a tractor has been developed. The experimental model showed that the implementation of the proposed hydraulic control system fur the prototype design of a slope land tractor was feasible. The front axle was designed as a center pin type and the rear axle was designed as a trailing arm type. The leveling control of the body on the slope land was accomplished by controlling the height of the right and left trailing arms using the electronic controlled hydraulic cylinder. The maximum leveling control angles were ${\pm}$15$^{\circ}$ for roll angle and 7$^{\circ}$far pitch angle. The front and rear wheel drives were transmitted by gears from the main shaft to the final drive. The adaptability of the hydraulic control system was tested and investigated by analyzing the system response in time and frequency domain. The hydraulic control system on a step input showed a linearly increasing trend without any overshoot state. The hydraulic control system on a frequency input showed a little phase differences and gain drops within the range of 0.3Hz.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.6
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• pp.22-27
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• 1997

In general, the load which acts on the structure is almost independent of time in many locations. In this case. It is difficult to estimate the life with the service load history, because the structure is on the multi- axial and multi-point loading states. In this study, the service load of the excavator which is widely used in industry field was calculated using measured cylinder pressures and displacements. The fatigue life was estimated using the multi-axial and multi-point load counting method. Service load history of 4 pin joint which act independently each other is yielded by mult-axial and multi-point load counting method. The stress spectrum is yielded by superposition of the results of FEM stress analysis applied unit load. Palm- gren-Miner's cumulative Damage is 0.000804 for Von Mises equivalent stress sequence by one side fillet weld S-N curve. This result agress with Bench test results. As a result of this study, the fatigue life esti- mation using the multi-axial and multi-axial and multi-point load counting method is useful.

• KSTLE International Journal
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• v.3 no.1
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• pp.1-6
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• 2002

The purpose of this paper is to investigate the effects of design parameters on the friction loss in piston skirt. An analytical model to describe the friction characteristics of piston skirt has been presented, which is based on the secondary motion of piston and mixed lubrication theory, It could be shown that the skirt friction closely depends on the side force acted on the piston pin. The side force is inf1uenced by cylinder pressure at low engine speed, but by inertia force at high engine speed. The usage of extensive skirt area and low weight piston is effective to reduce the friction loss at high speed. The low viscosity oil considerably decreases viscous friction as engine speed increases, but it increases boundary friction at low engine speed. From the parametric study, it is found that the skirt axial profile is the most important design parameter related to the reduction of skirt friction.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.160-165
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• 2005

The proceeding bearings of marine diesel engine are affected by dynamic loads from the cylinder gas pressure and the inertia force from the crank mechanism. Oil film must support the load of the shaft and it also must protect the proceeding and the bearings from damage. This study uses Goenka's new curve fit to carry out the theoretical analysis of oil film in proceeding bearings for MAN B&W 12K90MC-C and Hyundai Heavy Industry Co., Ltd HiMSEN H21/32 Engine. The applied engine's analysis results show the behavior of the proceedings in main and crank pin bearings. The results of this study will be the proper criteria for the proceeding bearings design and be available for development of the new technology in the proceeding bearing and for the high strength lining coating.

• Tribology and Lubricants
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• v.10 no.1
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• pp.14-26
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• 1994

The minimum oil film thickness(MOFT) in the connecting-rod bearing of a 1.5 liter, L-4, gasoline engine is measured up to 5500 rpm and calculated to study the dynamically loaded engine bearing. Short bearing approximation and Mobility method are used for theoretical analysis of oil film characteristics. And cylinder pressure, crank-pin surface temperature and bearing temperature are measured as the input data of theoretical analysis. The MOFT are measured by the total capacitance method(TCM). To improve the reliability of the test results, a reasonable determination method of bearing clearance is introduced and used, and the effects of cavitation and aeration on the test results are neglected. The crankshaft is grounded by means of a slip ring. A scissor type linkage system was developed to measure the MOFT and bearing temperature. The effects of engine speed, load and oil viscosity on the measured and calculated minimum oil film thicknesses are investigated at 1500 to 5500 rpm. From the comparison between the measured and calculated MOFT, it is found that a qualitative similarity exists between them, but in all cases, the measured MOFT are smaller than those calculated.