• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.5
• /
• pp.282-288
• /
• 2010

Experiment on the surface characteristics of polymer films treated by atmospheric pressure plasma has been conducted. We chose the process parameters as frequency, gas flow, treatment time, and scrutinized the effects of the process parameters on the surface characteristics of polymer materials by measuring the contact angle and examining SEM. As the result, the surface characteristics highly depends on frequency, reaction gas and treatment time. In the case of PC substrate, the contact angle was changed from $83.5^{\circ}$ (before plasma treatment) to $30^{\circ}$ (after plasma treatment) at 30 kHz, CDA 0.6%, and number of repeat 7. In the case of PET substrate, the contact angle change was found from $59^{\circ}$ to $23.5^{\circ}$ at 20 kHz, CDA 0.6%, and number of repeat 7. In the case of EVA substrate, it shows from $84^{\circ}$ to $44.2^{\circ}$ at 30 kHz, CDA 0.6%, and number of repeat 7.

• Tribology and Lubricants
• /
• v.10 no.2
• /
• pp.51-55
• /
• 1994

Rolling friction test was carried out to investigate the effect of the wear amount on rolling contact fatigue process in lubrication oil. The methods of this process were conducted at two Hertzian contact pressure and three slide ratio in each case by employing normalized and annealed carbon steel. During process of the rolling contact fatigue, the number of rotation until surface damage was occurred, the wear amount of rolling contact surface, and residual stress and half-value breadth using X-ray reflection on rolling contact surface were investigated. The result of this study shows that rolling contact fatigue process was directly influenced by wear trend and was confirmed by change of residual stress and half-value breadth on rolling contact surface.

• Tribology and Lubricants
• /
• v.10 no.3
• /
• pp.71-77
• /
• 1994

Rolling friction test was carried out to investigate the effect of the wear amount on rolling contact fatigue process in lubrication oil. The methods of this process were conducted at two Hertzian contact pressure and three slide ratio in each case by employing normalized and annealed carbon steel. During process of the rolling contact fatigue, the number of rotation until surface damage was occurred, the wear amount of rolling contact surface, and residual stress and half-value breadth using X-ray reflection on rolling contact surface were investigated. The result of this study shows that rolling contact fatigue process was directly influenced by wear trend and was confirmed by change of residual stress and half-value breadth on rolling contact surface.

• Journal of Information Technology Services
• /
• v.8 no.1
• /
• pp.29-45
• /
• 2009

In this research, a model to measure the correlation between the performance of customer contact center and the business performance is developed using the well-known model, the market damage model of TARP. Three hypotheses are suggested and verified using real customer profit data and customer access data of the Industrial bank of Korea. As a result of this research, we know that there is a positive relation between increase of business profit and contact experience of customers to customer contact center. Also, customer satisfaction level for customer contact center contact experience is positively correlated with increase of business profit of the company. However, we could not find a meaningful correlation result between number of contacts to customer contact center and the business profit. Although this study is based on a particular one company data, the analyzation framework can be applicable to other banking companies for showing relations between performance of customer contact center and business profit of the company.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1994.10a
• /
• pp.837-842
• /
• 1994

The boundary element method was used for studying singularities of an interface crack with contact zones. Because the contact zone size was extremely small in a tention field, a large number of Gaussian points were is used for numerical integration of the Kernels. In order to estimate the contact zone size, iteration method was used. The interface crack tips with contact zones showed no oscillatory behavior and J-integral values across the interface were conserved.

• The Journal of Korean Academy of Prosthodontics
• /
• v.28 no.2
• /
• pp.77-90
• /
• 1990

The purpose of this study was to compare the amount of the vertical pin opening of $33^{\circ}$ resin and $0^{\circ}$ resin teeth during processing and to determine whether the changes in tooth contacts by using articulation ribbon and T-Scan system follow any identifiable pattern, and to determine if there is any correlation between the changes in tooth contacts and the amount of the vertical pin opening after processing. Through statistical analyses on the data from this study, the following conclusions were obtained. 1. The amounts of the vertical pin opening were 0.78m, 0.87mm for $0^{\circ}$ teeth and $33^{\circ}$ teeth, respectively. But there was no significant difference between them. 2. The total number of contact points recorded by articulating ribbon after processing was decreased to 442.5% of that before processing. 3. The mean values for the number of contact points per tooth recorded by articulating ribbon after processing were 4.3 for the second molar, 3.8 for the first molar, 1.3 for the second premolar, 0.8 for the first premolar. The reduction of contact points per tooth became greater moving in an anterior direction. 4. The correlation between the reduction of contact points and the amount of the pin opening after processing was not significant. 5. The mean values for the numbers of contact points per tooth recorded by T-Scan system after processing were 2.2, 2.5, 1.0, and 0.5 at the second molar, the first molar, the second premolar, and the first premolar, respectively. 6. The correlation between the number of contact points by using articulating ribbon and TScan system after processing was not significant.

• Journal of Korean Ophthalmic Optics Society
• /
• v.21 no.3
• /
• pp.215-225
• /
• 2016

Purpose: The aim of this study was to figure out how the characteristics of soft contact lens materials and pigmentation affect the adherence of C. albicans on soft contact lenses pre-deposited with tear constituents. Methods: The adherent number of C. albicans on clear soft contact lenses (hereinafter clear lenses) and circle soft contact lenses (hereinafter circle lenses) made of etafilcon A, hilaiflcon B and nelfilcon A, respectively, was measured before and after the deposition of artificial tear. Also, bacteria adherence on lenses were observed by a scanning electron microscope. Results: Adherence of C. albicans was significantly different according to lens materials. The amount of adsorption was not different between clear lenses and circle lenses made of etafilcon A however, the number of bacteria absorption was bigger in hilafilcon B and nelfilcon A lenses. More absorption of C. albicans was found in the non-pigmented central area compared the pigmented area, and non-pigmented peripheral area has more bacterial absorption than non-pigmented central area. The number of C. albicans decreased in the case that tear protein was pre-deposited. The maintenance of antibacterial activity against C. albicans was different according to lens materials thus, etafilcon A has the longest period of its maintenance. Conclusions: It was revealed that the number of C. albicans was different according to the characteristics of lens materials, pigmentation or non-pigmentation, the pigmented area of soft contact lenses. Thus, it is suggested that the management method should be different according to the adsorption characteristics of C. albicans.

• Journal of Oral Medicine and Pain
• /
• v.32 no.1
• /
• pp.105-111
• /
• 2007

Correlation between occlusal contact pattern and TMD have been hypothesized and partially investigated but results are controversial and not conclusive. The purposes of this study were to compare right-to-left difference of occlusal contact pattern, through contact points, contact force and occlusal balance, in the patients with unilateral TMD and also to evaluate its change related with TMD treatment. 36 patients with unilateral TMD from Department of Oral Medicine in Dankook University Dental Hospital were selected in this study (M:F=7:29, mean age of $29.2{\pm}14.8$ years). A computerized T-Scan II system (Tekscan, INC., USA) was employed for occlusal analysis and the simultaneity and occlusal balance through the number of tooth contact and magnitude of contact force were determined before and after TMD treatment. The number of contact points and contact force was more on the unaffected side than the affected side before treatment (p=0.056 and p=0.060, respectively) while significant difference between both sides was not found after treatment. The number of contact points and contact force on the affected sides significantly increased after treatment (p=0.038 and p=0.052), but the unaffected sides exhibited no significant difference between before and after treatment. In addition, sides difference in relative contact force decreased from about 27% to about 12% after TMD treatment (p=0.001). According to the results of this study, it is likely that unilateral TMD impairs right-to-left occlusal balance and that conservative TMD treatment alleviates the imbalance, subsequently leading to more symmetrical occlusal condition with increased contact points and force.

• Journal of Wind Energy
• /
• v.14 no.4
• /
• pp.21-28
• /
• 2023

This study focuses on the analysis of slewing ball bearings in wind turbines. Slewing bearings have an outer diameter of several meters, and hundreds of balls are in contact with the raceway. Due to the large number of balls and raceway contact conditions, it is difficult to accurately analyze contact stresses using general analysis techniques. To analyze the contact stress of a slewing ball bearing, the sub-modeling method is applied, which is a technique that first analyzes the displacement of the entire model and then analyzes the local stress at the point of maximum displacement. In order to reduce the displacement analysis time of the entire ball bearing, the technique of replacing the ball with a nonlinear spring is adopted. The analytical agreement of the simplified model was evaluated by comparing it with a solid mesh model of the ball for three models with different spring attachment methods. It was found that for the condition where a large turnover moment is applied to the bearing, increasing the number of spring elements gives the closest results to modeling the ball with a solid mesh.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.4 s.193
• /
• pp.109-114
• /
• 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.