• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.5
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• pp.377-384
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• 2004

An Amplitude Proportional Friction Damper (APFD), in which the friction force is proportional to the system displacement, has been introduced and mathematically modeled. To understand the damping characteristics of APFD, analytical solutions for the impulse response has been derivedand compared to the viscous damper. It is found that APFD system has very similar damping characteristics to viscous damper even though it is a friction damper. APFD may be used as a cost-effective substitution for the viscous damper and could also be used to improve the simple friction or Coulomb dampersince APFD works with no stick-slip and always returns to original position when external disturbance is disappeared.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.450-455
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• 1997

In recent years the research and development about the new material proceeds rapidly and actively in building industry. We are concerned with high-strength concrete as a new material. As the building structure becomes bigger, higher and more specialized, so does the demand of material and member with high strength for building expands greatly. In the future, we will quite need to research repair and rehabilitation to make high strength concrete structural building for our safe. So, I did an study on carbon fiber sheet rehabilitation(CFSR) of reinforced high strength concrete beams. The carbon fiber reinforced plastic(CFRP) bonding method is widely used for reinforcing the existing concrete structure among the various methods. The test results indicate that CFS is very effective for strengthening the damaged beams and controlling deflections of the repaired beams. When carbon fiber sheet rehabilitation of reinforced high strength concrete beams happened diagonal crack, the increase in the number of CFS layer didn't effect the increase in strength of beams. Also, by changing the CFS stick position gave diversified ultimate load in CFSR beams.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.720-723
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• 2005

We studied the quantitativity of the image sticking which is occured by the resicual DC in the fringe-electric field switching (FFS) mode. Actually, in the FFS mode driven by the strong fringe electric field, the asymmetric residual DC was formed in the bottom substrate. It made the impurity ion stick to the alignment layer such as polyimde layer. Thus, the differnece of the luminance existes after the stress check pattern is applied to the panel so that we can see the image sticking. This image sticking decreases as the residual DC value between specific patterns decreases. Therefore, it is necessary to control the residual DC for the FFS mode with the high image quality. It is possible to eliminate the image stiking when the extra pixel voltage is applied through the circuit tunning for reducing the difference of residual DC accroding to the panel position.

• Journal of Mechanical Science and Technology
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• v.18 no.10
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• pp.1755-1762
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• 2004

Friction phenomenon can be described as two parts, which are the pre-sliding and sliding regions. In the motion of the sliding region, the friction force depends on the velocity of the system and consists of the Coulomb, stick-slip, Streibeck effect and viscous frictions. The friction force in the pre-sliding region, which occurs before the breakaway, depends on the position of the system. In the case of the motion of the friction in the sliding region, the LuGre model describes well the friction phenomenon and is used widely to identify the friction model, but the motion of the friction in the pre-sliding such as hysteresis phenomenon cannot be expressed well. In this paper, a modified friction model for the motion of the friction in the pre-sliding region is suggested which can consider the hysteresis phenomenon as the Preisach model. In order to show the effectiveness of the proposed friction model, the sliding mode controller (SMC) with hysteresis friction compensator is synthesized for a ball-screw servo system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.492-497
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• 2013

In this study, a parametric study is performed to investigate the squeal noise of an automobile water pump. The squeal noise studied in this paper is generated by the self-excited torsional resonance of the rotating shaft, and this noise is related to the stick-slip phenomenon of the mechanical seal in the water pump. The mechanical seal friction has the characteristics of the negative velocity-gradient. The equations of motion of multiple-degree-of-freedom torsional vibration model is constructed by the Holzer's method and then the equation is transformed to an equivalent single-degree-of-freedom torsional resonance simulation model. A squeal noise criteria is determined by the simulation model to perform the parametric study. The design parameters(the mass moment of inertia of the pulley, the mass moment of inertia of the impeller, the length of the shafts, the radius of the shafts, spinning speed of the shafts, the position of the mechanical seal, radius of the mechanical seal, and normal load of the mechanical seal) are investigated to confirm the stability for the squeal noise.

• Journal of Power System Engineering
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• v.3 no.1
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• pp.16-22
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• 1999

The purpose of this study is to prevent the stick, scuffing, scratch between piston and cylinder, is to contribute the piston design such as piston profile, clearance by calculating reaction force by over-lap of piston skirt, as measuring the temperature distributions of cylinder wall. The experiment has been peformed to obtain data during actual engine operation. Temperature gradient in peripheral and axial distributions of cylinder wall according to torque and speed of engine were measured by use of an 800cc class gasoline engine. The results obtained are summarized as follows ; 1) The temperature of cylinder wall at TDC was about $50{\sim}75^{\circ}C$ higher than temperature of cooling water. 2) The rear side temperature of top dead center was $141^{\circ}C$(1/4 load) in axial distribution, whereas the rear side of midway position temperature was $98^{\circ}C$. 3) The temperature of cylinder wall increased in according to rising temperature of cooling water. 4) The thrust side temperature of cylinder wall was about $15^{\circ}C$ in all load test. 5) The rear side temperature of top dead center was $159^{\circ}C$ (1/2 load) in peripheral distribution, it was about $39^{\circ}C$ higher than thrust side temperature.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.7
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• pp.624-630
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• 2013

In this study, a parametric study is performed to investigate the squeal noise of an automobile water pump. The squeal noise studied in this paper is generated by the self-excited torsional resonance of the rotating shaft, and this noise is related to the stick-slip phenomenon of the mechanical seal in the water pump. The mechanical seal friction has the characteristics of the negative velocity-gradient. The equations of motion of multiple-degree-of-freedom torsional vibration model is constructed by the Holzer's method and then the equation is transformed to an equivalent single-degree-of-freedom torsional resonance simulation model. A squeal noise criteria is determined by the simulation model to perform the parametric study. The design parameters(the mass moment of inertia of the pulley, the mass moment of inertia of the impeller, the length of the shafts, the radius of the shafts, spinning speed of the shafts, the position of the mechanical seal, radius of the mechanical seal, and normal load of the mechanical seal) are investigated to confirm the stability for the squeal noise.

• Journal of Information Technology Applications and Management
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• v.25 no.4
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• pp.23-39
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• 2018

The purpose of this study was to investigate empirically whether the expected effects of smart work in organizations were different between job types and positions. The development of information technology is demanding innovation of working style within the enterprise. There is a tendency to prefer the face-to-face working style in traditional organizations in the case of some positions or job types. However, many companies are carrying out smart work such as teleworking or telecommuting, flexible working time. But many companies still stick to their existing working methods. There is also the causal relationship between accepting attitudes toward smart work and expectation effects, depending on the position and the job types, even within the same organization. As a result of research, causal relationship analysis showed that the significant factors affecting productivity were teleworking and increasing work efficiency. The national social cost savings were influenced by the improvement of quality of life and flexible working hours. In order to activate communication within the organization, there was a positive effect on the increase of work efficiency. Only flexible working hours between the general manager and subordinates showed a significant difference.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.1
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• pp.51-62
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• 1994

The sagittal split osteotomy of the mandibular ramus is a common procedure which has been used in the correction of mandibular deformities for a few decades. Although the technical improvements have increased the reliability and stability of SSRO procedure, the postoperative relapse is imperative and clinically more significant than any other complication. One of the major causes of the relapse is due to the displacement of the proximal segment during SSRO procedure, which is well documented in the literature. Therefore it is important to preserve the original position of the proximal segment during SSRO proced and maxillofacial fixation period. In the case of mandibular asymmetry, if one side of mandible is advanced and the other side of mandible is setback during SSRO procedure, the proximal segment in the advancement site will rotate laterally and the proximal segment in the setback site will rotate medially. For the prevention of the lateral rotation or flaring of the proximal segment in the advancment site. we deliberately fracture the posterior protion of the distal segment in green-stick fashion during SSRO procedure, and there is no need to fix the fractured lingual segment. We fix the two osteotomized bony segments in the buccal cortex area rigidly with adjustable monocortical plates and screws. During SSRO procedure the lingual fracture technique was applied to nine patients with severe mandibular asymmetry who underwent orthognathic surgery in our hospital since march, 1992. These clinical experiencies enable us to find the lingual fracture technique has the following advantages. 1. The proximal segment is displaced minimally. 2. The osteotomized bony segments are contacted intimately. 3. The postoperative relapse and the healing period are decreased.

• Journal of Korean Medical classics
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• v.33 no.1
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• pp.61-80
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• 2020

Objectives : To clarify the construction, changes, and contents of the diagrams of spleen through comparison of 30 different diagrams originated from Mingtangzangfutu. Methods : The diagrams were analyzed in whole shape, ratio between width and height, shape of the lower part, and concavo-convex of the middle part, then matched to the characteristics of the section diagram. The contents of the diagram of the spleen were newly interpreted with comparison to the classical texts. Results : The whole shape is described to be a long sword, long stick, bottle gourd, western pear, sole of feet. The height to width ratio was mostly above 4.0:1, but those listed in the 『Bianquemaishunaning』 and 『Hehensancaituhui』 were 1.9:1~1.0:1, most similar to the numbers described in the 『Nanjing』. The shape of the lower part was narrow and sharp, narrow and flat or wide and flat. To analyze through affiliation characteristic, properties of other affiliations could be found. In comparison to classical texts, the diagrams could be found to be affected by 『Nanjing』 and Wangbing's annotations. The diagrams of the spleen should be composed of the spleen, the cord of spleen, and Sangao(散膏); but those which distinguish the spleen and the cord of spleen are twelve. The description of its shape as being similar to sword or sickle seems to come from Lichan's misunderstanding of the diagram in 『Zhenjiujuying』. Those that mention Sangao are merely two and their opinion on the position are different from each other; both did not identify it with the pancreas. Conclusions : In the process of the diagrams differentiating into 30 they were affected by the classical texts. The various changes seem to come from difference in understanding of the content composition of the diagram of the spleen.