• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.345-357
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• 2006

By employing the concept of equivalent linkage, this paper presents an analytical method for analyzing the mechanical errors of disk cam mechanisms with a flat-faced follower. The resulting error equations do not really involve the location of the curvature center of the cam profile, and locating the curvature center of the cam profile is not essential. The resulting errors are significantly affected by the pressure angle, and the smaller pressure angle will result in the smaller mechanical error. In the worst case, owing to the joined effects of various design parameters, the accuracy of the follower motion may degrade considerably. For the oscillating follower case, all acceleration error functions have a sudden change at every beginning and at every end of the motion even though the theoretical follower displacement is cycloidal motion.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.121-128
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• 1999

In this study, a numerical procedure to analyze 3-dimensional unsteady elastohydrodynamic lubrication was developed. The procedure was applied to the actual cam and roller follower of the valve mechanism for a marine diesel engine. The pressure distribution between the cam and roller follower was calculated for the several cam rotating angles. The pressure spike is shown near the roller edge and it is getting higher as the external load is increased. The roller profile for reducing the pressure spike was suggested by the Hertzian contact analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.4
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• pp.184-192
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• 2001

Cam/tappet wear is one of the critical concerns in valve train deign. Maximum contact stress and minimum oil film thickness between the cam and tappet are usually checked for the estimation of wear characteristics. If the two extreme cases arise simultaneously, there is a strong possibility of cam/tappet wear. In this paper, effects of valve train layout on the wear characteristics were studied. Especially for swinging arm type valve trains, initial geometric layout must be very carefully defined to avoid wear problems. The study was performed fur an end pivot type OHC valve train, which had severe wear problems. Analysis results show that some geometric parameter affect very sensitively on the wear characteristics. Experiments were also performed for the original and modified valve trains, which strongly support the analysis results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.417-420
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• 2009

The hot forming process of a CAM for vessel engine was designed by finite element (FE) simulation and experimental analysis. An aim of process design was to achieve the near-net shaped CAM forgings by hot forging process. Based on the compression test results of the low alloy steel, deformation processing map was generated using the superposition approach between the dynamic materials model (DMM) and flow stability and/or instability criteria. From the processing map, the initial heating temperature was determined as $1200^{\circ}C$. FE analysis was simulated to predict the formation of rolling defects and deformed shape with different forging designs. Optimum process design suggested in this work was made by comparing with the CAM for vessel engine manufactured by actual forging process.

• Journal of Technologic Dentistry
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• v.42 no.1
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• pp.45-53
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• 2020

Purpose: The purpose of this study was to investigate the current status and satisfaction of dental CAD/CAM system. Methods: A survey of dental technicians was conducted and a total of 353 responses were used for analysis. The satisfaction difference according to career was analyzed by ANOVA and tukey HSD (α = .05). Results: Satisfaction with the design program was 3.64 ± .86, the highest among all items. On the other hand, the satisfaction with price was 2.75 ± 1.02, which was the lowest. The difference according to career was statistically significant in the following items. Frequent breakdown, single crown margin, bridge crown margin, retentivity, price, A/S, equipment training (p<.05). Conclusion: As the materials applied to dental CAD/CAM are expanding and the types of prostheses are diversified, the use rate of CAD/CAM is continuously increasing. The dental CAD/CAM system will need to be improved in a way that will satisfy all patients, dentists and dental technicians.

• Journal of Technologic Dentistry
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• v.37 no.4
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• pp.271-284
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• 2015

Purpose: The purpose of this study was to examine the usage of CAD/CAM, which is one of dental technologist duties, in an effort to look for any possible changes in the usage of CAD/CAM. It's specifically meant to compare the results of this study with those of Lee Jong-do, Park Kwang-Sig(2011)'s study in March, 2011, to determine if there were any changes over the past four years. The selected variables that were investigated were the ownership of CAD/CAM, awareness of it, the route of acquiring the first information on it, the merits and demerits of its usage, usage experience and educational experience about it. Methods: An online survey was conducted on the dental technologists who worked in urban communities including metropolitan cities to find out the usage of CAD/CAM in 2015 from July 15 to 31, 2015, after existing questionnaire items were modified. The collected data were analyzed by IBM SPSS statistics 22.0, and statistical data on frequency, percentage, mean and standard deviation for each item were obtained. To figure out the characteristics of the subjects and the relationship between their occupational characteristics and the usage of CAD/CAM, crosstabs, independent-samples t-test and one-way ANOVA were utilized. As for the usage of CAD/CAM in 2011, the results of Lee Jong-do, Park Kwang-Sig(2011)'s study were selected, and then a comparative analysis was made. The level of significance was all set at .05. Total 250 questionnaires were distributed to them, and 190(76.0%) were returned. After excluding 23 whose answers were uncertain or seemed to lack reliability, total 167(66.8%) were used in final analysis. Results: As a result of analyzing the usage of CAD/CAM that was one of dental technologist duties, there was a great increase in the ownership of CAD/CAM in their workplaces from 2.4 percent in 2011 to 71.7 percent in 2015, and there was an improvement in awareness about it and the necessity of its usage as well. In 2011, the Internet and mass media were the most common route that they got to know about it. They had a strong tendency to acquire related knowledge through education in 2015, and there were some changes in the products that they used or preferred. In both years, the great merit of CAD/CAM was the simplified manufacturing process of restoration, and it had another great advantages in 2015 such as the improved quality of restoration or improved environments for dental technology. Concerning disadvantages, high price was a big problem in 2011. In 2015, not only price but the burden of material costs, frequent breakdown, poor demand among dental clinics and a lack of CAD/CAM professionals were pointed out a lot. In the future, this researcher intends to make research to seek ways of improving CAD/CAM professionals. Conclusion: There was more awareness of CAD/CAM in 2015 than in 2011 when the changes in awareness of it were analyzed, and the finding suggest the necessity of sustained education and concern.

• Korean Journal of Adult Nursing
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• v.19 no.3
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• pp.447-458
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• 2007

Purpose: This exploratory study was to identify the use of complementary and alternative medicine(CAM) in women with breast cancer and to analyze which factor influence CAM use. Methods: 114 patients with breast cancer were identified and approached. The instrument used to gather data were the common types, main reasons and effects as well as stress, mood states and fatigue. Results: 42.7% of all participants reported the use of CAM. The most common types of CAM used were Phellinus linteus, elm tree, and vitamin C. The main reasons for CAM use were to boost the immune system and to prevent recurrence. Prayer, massage, Shitake mushroom, and Ganoderma lucidum were, identified as being more effective than others. 93.6% of the respondents informed their physicians of their use of CAM. Logistic regression analysis determined that stress, mood states, and duration after diagnosis were factors significantly associated with CAM use. Conclusion: CAM use is increasing among patients with breast cancer. Health care professionals are in the main position to identify what treatments patients are using and implement CAM therapies that can be helpful to relieve patient symptoms related to treatment and psychological distress.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1299-1302
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• 2005

Current mechanical devices are trending toward being a small size, high speedy, automation. For performing these functions, machinery elements organizing a machine should be designed exactly. Cams have high confidence and economics in ablility to transmit a motion. Accordingly, A cam mechanism is very important for processing the machine automatically. This paper introduce an inverse cam mechanism. A square shaped cam which cannot be commonly analyzed is designed and manufactured by using the NURBS interpolation algorithm. The objective of this paper is to develop a computer-aided design program. In this paper, a displacement curve of oscillating motion inverse cam mechanism with square shaped follower is analyzed. The data is redistibuted by the NURBS algorithm. A cam shape is designed by the instant velocity center method, and simulated to verify the validity of the operation state.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.525-526
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• 2008

• Tribology and Lubricants
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• v.16 no.3
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• pp.201-207
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• 2000

The numerical procedure to analyze a non-steady 3-dimensional elastohydrodynamic lubrication on the cyclically loaded contact has been newly developed. The procedure was applied on the cam-roller contact of the valve mechanism for the marine diesel engine. Both the pressure distribution and the film thickness between the cam and roller follower were calculated for each time step of the whole cycle. The pressure spike is shown at the outlet of the roller edge and it is getting higher as the external load is increased. The film thicknesses in the result of the non-steady analysis have a tendency to increase compared to those in the result of the analysis with the assumption of steady state. Therefore, the surface roughness of the non-steady contact need not be limited below that of the steady contact of the equivalent operating conditions.