• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.12
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• pp.1013-1019
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• 2016

CFRP is the composite material manufactured by the hybrid resin on the basis of carbon fiber. As this material has the high specific strength and the light weight, it has been widely used at various fields. Particularly, the unidirectional carbon fiber can be applied with the layer angle. CFRP made with layer angle has the strength higher than with no layer angle. In this paper, the property of crack growth due to each layer angle was investigated on the crack propagation and fracture behavior of the CFRP compact tension specimen due to the change of layer angle. The value of maximum stress is shown to be decreased and the crack propagation is slowed down as the layer angle is increased. But the limit according to the layer angle is shown as the stress is increased again from the base point of the layer angle of $60^{\circ}$. This study result is thought to be utilized with the data which verify the probability of fatigue fracture when the defect inside the structure at using CFRP of mechanical structure happens.

• Journal of the Korea Convergence Society
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• v.11 no.9
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• pp.169-173
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• 2020

The structural analysis was performed at this study when the axle was loaded by using a total of three automotive support beam models, models A, B and C. Comparing with three models A, B, and C, the equivalent stress is considered to be good for its durability because model C is less than the yield stress of the material. The maximum equivalent stresses happening at models A and B are 1.8 times and 2.5 times higher than the yield stress, respectively, indicating that the material is fractured. So, it does not seem to be efficient as a support beam. Model C can be applied efficiently to the improvement design of axle support beams in terms of durability compared to models A and B. The strength of automotive support beam can be evaluated by applying this research result to the automotive part. And it is seen that this study is adequate at the efficient design and aesthetic convergence practically.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1495-1501
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• 2011

Fatigue life and vibration can be analyzed at automotive propeller shaft during driving in this study. The york part is shown with the maximum equivalent stress and displacement of $1.3177{\times}10^3$Pa and $3.6148{\times}10^{-4}$m. The possible life in use in case of 'SAE bracket' is the shortest among the fatigue loading lives of 'SAE bracket', 'SAE transmission' and Sample history. There are the most frequency as 80% in case of 'SAE bracket and the least frequency as 5% in case of Sample history'. Maximum amplitude displacement is 0.00261m at 58 Hz at forced vibration. As the result of this study is applied by the propeller shaf, the prevention on fatigue damage and the durability are predicted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.39-44
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• 2013

Seat is the part relevant to comfortableness and safety among automotive parts directly. It also should have sufficient stiffness and strength to satisfy these conditions and ensure the safety of passenger. Automotive seat is modelled with 3D and is simulated with structural analyses about three kinds of experiments by before and after gap, side gap, before and after moment strength. As analysis result, deformation angles of $0.038^{\circ}$ and $0.04^{\circ}$ are respectively shown at before and after gap test, side gap test. Through before and after the moment strength test, maximum total deformations of 0.18946mm and 3.2482mm are respectively shown at front and rear loads. By the study result of no excessive deformation and no fracture at automotive seat frame, the sufficient rigidity and strength to guarantee the safety of passenger can be verified.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.163-172
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• 2010

There are many efforts for expanding bikeway plans and increasing bike utilization. In this study the authors try to find the primary factors that affect bike users' satisfaction under limited budgets. As satisfaction is a qualitative variable, the authors developed a bike user satisfaction model by using structural equation methods. The bikeways are distinguished between bike lanes on public roads and exclusive bikeways along the Han River, as the characteristics and attributes should be different. The model shows bikeways on public road have a user satisfaction equal to 0.248*(safety)+0.405(accessibility). Bikeways along the Han River have a user satisfaction equal to 0.437*(accessibility)+0.405*(economic feasibility). In both types, accessibility affects satisfaction. Safety in more important to users on public roads, while economic feasibility affects those on the Han River bikeways.

• (The)Study of the Eastern Classic
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• no.73
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• pp.219-248
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• 2018

Confucius said, "I do not murmur against Heaven. I do not grumble against men. My studies lie low, and my penetration rises high. But there is Heaven;-- that knows me!" and said, "Does Heaven speak? The four seasons pursue their courses, and all things are continually being produced, but does Heaven say anything?" The only key Jen仁-concept of confucianism is based on Tien(天). This articles intend to articulate Dasan's commentary of Tien(天)-concept in Confucian analects("論語"). Dasan was to contrast Chu-Hsi's a commentary in assembled commentary of Confucian analects("論語集註") with 2) old commentary of Confucian analects("論語注疏"), and reestablished Tien(天))-concept on old & contemporary commentary of Confucian analects("論語古今註"). He analyzed, deconstructed, and re-interpretations Tien(天)-paragraph of in Confucian analects. Dasan collected, complied, and re-interpretation dispersed original meaning of Tien(天)-paragraph of Confucian analects. Cheong Yagyong tried to recover the original meaning of Tien(天)-concept in Confucian analects.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.297-302
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• 2019

A-pillar is closely related to safety for the purpose of protecting the bodies of passengers by mitigating the impact that may be caused by the vehicle being overturned while driving. Therefore, the A-pillar should protect these parts from a variety of dynamic loads. This study result is thought to contribute for the strength and durability of A-pillar by designing two types of parts before making this product and analyzing the product which thickness is adjusted for the light weight of vehicle. If this study result is practically applied to the parts of A-pillar in a car, it is considered that the damage can be protected by the durability verification of design. By utilizing the data of analysis and design on the strength and durability of automotive A-pillar in this study, the esthetic sense can be given by being grafted onto the real automotive part.

• Journal of the Korea Convergence Society
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• v.10 no.10
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• pp.123-128
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• 2019

The structural analysis for light weight on the brake pedal of the racing spec installed with the balance bars of the four models were performed in this study. By utilizing two materials of steels and aluminum alloys, four shapes were analyzed. It is generally assumed that the magnitude of force a person may incur when riding in a car is 1000 N. The fixed points are designated as the parts at which the bolts and pedals are fixed and the mounting part of the balance bar applied by the stress transmitted through the rod when the pressure of the master cylinder rises and the operation stops. Through this analysis study, it is thought that the vulnerability of each brake pedal model can be investigated and the transmission efficiency of the brake pedal can be increased by light weight. As the design data with the durability of brake pedal obtained on the basis of this study result are utilized, the esthetic sense can be shown by being grafted onto the part of car at real life.

• Journal of the Korean Data and Information Science Society
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• v.23 no.5
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• pp.895-904
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• 2012

This study aims to examine the effects of a 12-week compound exercise program (aerobic exercise+weight training) on obese middle school girls' leptin and insulin before and after the exercise. This is achieved by dividing obese middle school girls whose body fat percentage is over 30% into a compound exercise group (n=20) and a control group (n=20) and conducting comparative analysis on them.After the Shapiro-Wilk normality test of the variables, a two-sample t-test was performed to see if the variables have the same mean between the compound exercise and control groups. A paired t-test was also performed to see if the changes in the variables before and after the compound exercise program were statistically significant. For all the statistical analysis, the significance level was set at ${\alpha}=0.05$. The results of this study showed the leptin and insulin levels in the combined exercise group had been significantly decreased. The regular 12 weeks of combined exercise is considered to have a positive impact on leptin and insulin levels in obese schoolgirls.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.4
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• pp.283-287
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• 2014

This experiment was conducted to determine methane production and emission factors for a range of roughage diets fed to Hanwoo cows at a level of maintenance energy requirement. Seven cows were fed mixed hay only, 12 cows were fed mixed hay containing 30~50% rice straw and 6 cows were fed a mixed hay diet supplemented with 1.0 kg of wheat bran. Each cow was placed in a metabolic crate for 10 consecutive days, including last 7 days for sampling of feces and urine. At the end of the sampling period, the cows were transferred to an open-circuit respiration chamber for 24 consecutive hours. Methane conversion rate (5.5~6.2%, mean value = 5.8%) and emission factor (33.6~38.6 kg/head/year, mean value = 35.2) were not significantly affected by the diets although the mixed hay only diet resulted in 11 and 15% higher respective rates than the other two. However, in light of the many assumptions that forage with good quality might reduce methane production, additional experiments should be required for participation in the greenhouse gas emission trading system.