• Structural Engineering and Mechanics
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• 제34권3호
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• pp.319-334
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• 2010

The dynamic response of a finite Bernoulli-Euler beam resting on a tensionless Pasternak foundation and subjected to a concentrated harmonic load is investigated in this study. This load may be applied at the center of the beam, or it may be offset from the center. Since the elastic foundation is assumed to be tensionless, the beam may lift off the foundation, resulting in contact and non-contact regions in the system. An analytical/numerical solution is obtained from the governing equations of the contact and non-contact regions to determine the coordinates of the lift-off points. Although there is no nonlinear term in the equations, the problem appears to be nonlinear since the contact regions are not known in advance. Due to that nonlinearity, the essentials of the problem (the coordinates of the lift-off points) are calculated numerically using the Newton-Raphson technique. The results, which represent the symmetric and asymmetric responses of the beam, are presented graphically in this work. They illustrate the effects of the forcing frequency and the beam length on the extent of the contact regions and displacements.

• 로봇학회논문지
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• 제8권3호
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• pp.206-216
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• 2013

We investigate the role of contact location information on the perception of local features during contour following in a virtual environment. An absolute identification experiment is conducted under force-alone and force-plus-contact-location conditions to investigate the effect of the contact location information. The results show that the participants identify the local features significantly better in terms of higher information transfer for the force-plus-contact-location condition, while no significant difference was found for measures of the efficacy of contour following between the two conditions. Further data analyses indicate that the improved identification of local features with contact location information is due to the improved identification of small surface features.

• 대한치과보철학회지
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• 제32권1호
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• pp.171-178
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• 1994

This paper reports histologic and histomorphometric results concerning bone healing around vent area of 16 titanium plasma sprayed IMZ implants in rabbit femurs. Bone contact around the implants 8 weeks after placement showed a great deal of variability from 14.32% to 65.94% and mean total bone contact was 33.96%. The mean percent amount of bone contact was 43.68% in inner surface of vent and 27.79% in outer surface. Histologic examination of horizontal sections of vent area showed direct contact with living lamellar bone and some woven bone. The implants surface area not in contact with bone was in contact with collagenous connective tissue. But there was no sign of foreign-body reaction.

• 한국정밀공학회지
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• 제24권4호
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• pp.109-114
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• 2007

The mobility (degree of freedom) of mechanisms can be regarded as independent coordinate to define its position. This concept is essential for kinematics, and for designing mechanisms in the practical point of view. Gruebler's equation has been applied to estimate the mobility using number of links and joints of a mechanism. In practical case, there are many types of mechanisms, which transfer motion by direct contact between two links. However, no exact kinematic definition has existed for the joint that the contact takes place in a mechanism. In this paper, a new concept of contact joint is defined and modified Gruebler's equation is suggested to calculate mobility of a mechanism with the joint. This concept would be useful in mechanism design because it will be possible to manage many contact mechanisms with kinematic exactness.

• 한방안이비인후피부과학회지
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• 제18권3호
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• pp.44-54
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• 2005

Background and Objectives: Allergic contact dermatitis is a common environmental health issue and seriously affect the patient's quality of life. The more our environment industrialized, the number of material that could cause the allergic contact dermatitis has been increased, consequently the prevalence of allergic contact dermatitis has been increased. In oriental medicine, clinically Chogam-Tang has been used fur the treatment of allergic dermatitis, eczema, atopic dermatitis etc. The objective of this study is to investigate the effects of Chogam-Tang on allergic contact dermatitis Meterial and Methods: Fifteen Sprague-Dawley rats were divided into three groups: normal, control, experimental group. Control and experimental group were induced allergic contact dermatitis, by DNCB. Experimental group was orally administered the Chogam-Tang. Each group was observed after 24, 48 and 72 hours. Contact hypersensitivity assay, melanin-erythema measurement, pH measurement skin moisture measurement and biopsy were performed. Results: 1. In contact hypersensitivity assay, experimental group showed decreased ear swelling compared with control group at 48hours. 2. ln melanin measurement there was no difference in three groups. 3. In erythema measurement experimental group showed reduction at 48. 72 hours. 4. In pH measurement, experimental group and control group showed increase in pH but there was no statistical significance. 5. In skin moisture measurement, experimental group showed higher skin moisture level than control group at 24 hours and showed lower skin moisture level at 72 hours, but there was no statistical significance. 6. In biopsy, experimental group showed decrement of Iymphocyte as time goes by, and regeneration of keratin layer was increased compared with normal group. Conclusions: Chogam-Tang shows anti-inflammatory effect in biopsy, improves hydration levels of skin, decreases erythema level on allergic contact dermatitis.

• 대한치과보철학회지
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• 제35권4호
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• pp.627-646
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• 1997

In order to find the degree of osseointegration at bone-implant interface of clinically successful implants, models including the 3.75mm wide, 10mm long screw type $Br{\aa}nemark$ implant as a standard and cylinder, 15mm long, 5.0mm wide, two splinted implants, and implants installed in various cancellous bone density were designed. Also, the amount of load and material of prostheses were changed. The stress and minimum contact fraction were analyzed on each model using three-dimensional finite element method(I-DEAS and ABAQUS version 5.5). The results of this study were as follows. 1. 10mm long, 3.75mm diameter-screw type implant had $36.5{\sim}43.7%$ of minimum contact fraction. 2. Cylinder type implant showed inferior stress distribution and higher minimum contact fraction than screw type. 3. As implant length was increased, minimum contact fraction was increased a little, however, maximum principal stress was decreased. 4. Implants with a large diameter had lower stress value with slightly higher minimum contact fraction than standard screw type. 5. Two splinted implants showed no change of minimum contact fraction. 6. The higher bone density, the lower stress value. 7. The material of occlusal surface had no effect on the stress of the bone-implant interface.

• 한국초전도ㆍ저온공학회논문지
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• 제24권4호
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• pp.40-45
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• 2022

The electrical/thermal stabilities and magnetic field controllability of a no-insulation (NI) high-temperature superconducting magnet are characterized by contact resistance between turn-to-turn layers, and the contact resistance characteristics are determined by properties of conductor surface and winding tension. In order to accurately predict the electromagnetic characteristics of the NI coil in a design stage, it is necessary to control the contact resistance characteristics within the design target parameters. In this paper, the contact resistance and critical current characteristics of a rare-earth barium copper oxide (REBCO) conductor were measured to analyze the effects of surface treatment conditions (roughness and oxidation level) of the copper stabilizer layer in REBCO conductor. The test samples with different surface roughness and oxidation levels were fabricated and conductor surface analysis was performed using scanning electron microscope, alpha step surface profiler and energy dispersive X-ray spectroscopy. Moreover, the contact resistance and critical current characteristics of the samples were measured using the four-terminal method in a liquid nitrogen impregnated cooling environment. Compared with as-received REBCO conductor sample, the contact resistance values of the REBCO conductors, which were post-treated by the scratch and oxidation of the surface of the copper stabilizer layer, tended to increase, and the critical current values were decreased under certain roughness and oxidation conditions.

• 대한치과보철학회지
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• 제36권4호
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• pp.598-614
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• 1998

This study was performed to investigate the influence of lateral guidance pattern and chewing pattern on masticatory muscle activity and occlusal contact pattern. Twenty-five patients with temporomandibular disorders and thirty students without temporomandibular disorders were selected for this study. Electromyographic examination and occlusal contact examination were performed simultaneously with Bio-Pak System (Bioresearch Inc.,U.S.A.) and T-Scan System(Tekscan Co., USA). The obtained results were as follows : 1. The EMG activity of masseter and anterior temporal muscle in patient group with canine guidance was higher than with non-canine guidance. but there was no significant difference (p>0.05). 2. The EMG activity of anterior temporal muscle in normal group with non-canine guidance was higher at preferred chewing side than at opposite side (p<0.05). 3. The EMG activity of masseter muscle was higher in normal group than in patient group (p<0.05). 4. The number of occlusal contact in patient group with canine guidance was higher than with non-canine guidance, but there was no significant difference (p>0.05). 5. The occlusal contact force at preferred chewing side was higher in patient group than in normal group(p<0.05).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.833-836
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• 2007

Load/Unload technology has more benefits than the conventional CSS technology. However, it remains unsolved technical problem on the unloading process. While the slider climbs up the ramp at the outer edge of the disk, the possibility of the slider-disk contact by lift-off force and rebound of the slider increases. This paper focuses on no slider-disk contact. To prevent the slider-disk contact, we apply the disk bump on disk outer edge proceeding unload. Firstly, in the simulation, the bump dimension is determined by changing bump design parameters. Secondly, dynamic stability of slider have to be checked on disk bump before unload analysis, and unload analysis is performed by applying stable bump shapes to unload simulation. Thirdly, we select optimal bump shape to improve unload performance by unload analysis. Finally, in the experiment, the disk bump is mechanically manufactured by pressing disk surface using diamond tip. That is variously processed by changing pressing pressure. After confirming bump shape by nano-scanner, proper bump shape is applied to real experimental unload process. Through this investigation, we propose the optimal bump design to prevent the slider-disk contact, and then we can realize improved unloading performance.

• 대한치과보철학회지
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• 제28권2호
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• pp.175-182
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• 1990

This study was performed to investigate the influence of occlusal change on the masticatory muscle activity. 8 students without any symptom of T.M.J. dysfunction, any history of prosthodontic or orthodontic treatment on dental college of WonKwang Univ. were participated in this study. The activity of masseter and anterior temporal muscles were measured by bioelectric processor(EM2, Myotronics, Inc., U.S.A.) during voluntary maximal clenching on natural teeth, by splint with bilateral posterior surface contact, by splint with unilateral posterior surface contact, and by splint without unilateral posterior teeth contact. The obtained results were as follows ; 1. The loss of posterior contact on noe side resulted in change of the activity of anterior temporal and masseter muscle during clenching on ipsilateral side, but there was no change of muscle activity on contralateral side. 2. The activity of anterior temporal and masseter muscle during clenching were not affected by the pattern of occlusal contact. 3. There were no difference between the activity of anterior temporal and masseter miuscle during clenching by natural teeth and by occlusal splint.