• Transactions of Materials Processing
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• v.26 no.1
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• pp.55-62
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• 2017

This paper proposes the process to develop a light-weighting automotive door assembly using high strength steel with low cost penalty. In recent years, the automotive industry is making an effort to reduce the vehicle weight. In this study, inner panels for automotive front door using thinner sheets and quenchable boron steel were designed to reduce the weight of conventional one. In order to evaluate the stiffness properties for the proposed door design, the several static tests were conducted using the finite element method. Based on the simulation results, geometry modifications of the inner panels were taken into account in terms of thickness changes and cost saving. Furthermore, a prototype based on the proposed design has been made, and then static stiffness test carried out. From the results, the proposed door is proved compatible and weight reduction of 11.8% was achieved. It could be a reference process for automotive industry to develop the similar products.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.4
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• pp.142-148
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• 2018

In recent years, Korea's aviation industry has been developing rapidly due to the emergence of low-cost airlines. In order to survive in such competition, airlines are making various efforts to save the operation cost as much as possible. Fuel costs account for more than 25% of operating costs. For airlines, reducing aircraft fuel costs is an important part of improving profitability. In this study, analyzing the difference weight between flightplan and W&B Manifest for calculated the fuel that was unnecessarily loaded. As a method to calculate the unnecessary fuel was used by Airbus company flight planning program.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.26-29
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• 2000

The conventional types of X-ray generators were bulky in physical size and heavy in weight and the control accuracies of the output voltages were not always satisfacotry. The high frequency switching inverter and converter technology on power conversion and control systems have been greatly closed up introducing power semiconducot devices. To decreasing the volume and the weight of high voltage transformer and to stabilize ripple. In this paper the newly developed x-ray generator in a low cost using duty modulation PWM inverter. This system verify improved performance by stabilize ripple of X-ray tube voltage and compared the reproducibility linearity and dose in single phase three phase and PSU.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.5
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• pp.360-366
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• 2013

For conventional electrical actuators, the materials are mainly made up of metals, which mean they are prone to corrosion and electrical sparking. Replacing these systems with polymer metal composite based materials can be solved both problems. Considering their excellent electromechanical property, low device fabrication cost, light weight, and good electrical conductivity, the actuator based on ionic polymer metal composite (IPMC) was fabricated using Nafion film, NaOH 0.1 molar solution, and Au electrode. IPMCs exhibit good electrostatic property which means they can in principle be used in making actuators based on electromechanical motions. The resistance measurements of Nafion film after soaking in NaOH and deionized water were demonstrated and compared each other. The result of sample soaked in NaOH showed better electrical conductivity than in deionized water. The fabricated IPMC actuator exhibits a large deformation of bending displacement of approximately 9 mm with applied low AC voltage 6.89 V at 2.84 Hz. The result of computer simulation was also very similar and shown as a bending displacement of 8.6085 mm.

• Korean Journal of Social Welfare
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• v.60 no.1
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• pp.233-250
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• 2008

The purpose of this study is to report a case of cost analysis for community-based social service centers for the disabled. This study analyzed 2002 accounting reports and annual business reports from 20 social service centers for the disabled. To identify weight of each service researchers surveyed each service in terms of significance, difficulty, and emphasis from managers among centers. For cost analysis, this study used TCA(Traditional cost accounting), rather than ABC(Activity-based costing) because of costs, time, and difficulty to find cost drivers. Findings indicate that average annual expenditure is about 1260 million Won. About 65.8% is for labor and another 13.2% is for programs. In addition, the cost for respite care service(1 hour basis) is 26,922 Won and job counselling with job capacity evaluation(2 hour basis) is 143,355 Won. These costs does not count on real estate costs and low labor costs. Thus, market price of those services should be higher than the above. This study analyzed the costs with service bassis rather than costing item basis. This method would provide more useful information to decision makers in relation to program expansion, reducement, and resources allocation etc.

• Korean Journal of Environmental Agriculture
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• v.20 no.2
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• pp.122-126
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• 2001

The effect of the fermented food wastes (FFW) on growth performance and feeding efficiency war investigated in growing-finishing pigs. Four treatments with different mixing rates [0% FFW (100% commercial diet: control) ; 25% FFW ; 50% FFW ; and 100% FFW] were tried. Twenty heads of cross-bred barrows ($Duroc\;{\times}\;Landrace$, average live weight : 28.5 kg) were divided into 4 treatments with 5 replicates. During entire feeding trial (10 to 27 week), average daily gain increased by 29.4% and 13.9% in 25% FFW and 50% FFW, but decreased by 38.2% in 100% FFW compared to control. Daily feed intake was the highest in 25% FFW and it greatly decreased in 50% and 100% FFW feeding. The amount of feeds required for weight gain was similar with control in 25% FFW or significantly decreased in 50% FFW, while greatly increased in 100% FFW feeding. Cost of feeds per kg weight gain was decreased by 28.6%, 49.4% and 32.6% in 25%, 50% and 100% FFW, respectively. The results showed that replacement up to 50% with fermented food wastes was advantageous with respect to feed efficiency and feed cost, but 100% FFW feeding was disadvantageous because of a very low feed efficiency.

• Korean Journal of Agricultural Science
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• v.45 no.2
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• pp.283-289
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• 2018

Agricultural gear reducers are used in a variety of agricultural machinery designs such as in agricultural tractors and transport cars, and even greenhouses. For greenhouses, a gear reducer is used to control windows on the side and the roof. Gear reducers for agricultural applications are designed using the empirical method because of the lack of a standard for experimentation. Simulation is necessary for the optimal design of an agricultural gear reducer. There are many advantages to this optimization such as low-cost maintenance, reduced size, and weight. In this study, bending and contact safety factor simulation for the gear reducer of a greenhouse was conducted by decreasing the face widths of helical gear shaft 2 and shaft 3 from 30.8 and 30 mm, respectively, at an interval of 4 mm. The bending and contact safety factors were calculated using AGMA standard. Simulation results showed that bending and contact safety factors decreased rapidly when the face width of the helical gear on shaft 2 was 30 mm and the face width of helical gear on shaft 3 decreased from 30.8 mm to 26.8 mm, suggesting that it would be safe to reduce the face width of the helical gear on shaft 3 to 26.8 mm. The reduction of the face width also reduced the weight of the agricultural gear. This study suggests that the agricultural gear reducer safety factor decreases as the face width decreases.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.597-604
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• 2006

Fiber Reinforced Polymer (FRP) is a relatively new material in the bridge construction. With high strength to weight ratios, excellent durability, and low life-cycle costs of FRP, FRP bridge decks can offer a low dead load, reduced maintenance, and long service life. Due to the lightweight of FRP, if existing concrete decks can be replaced with the FRP decks, the load carrying capacity of superstructure can be increased without strengthening of girders. In this study, we have conducted an experiment on 7 cases of connection conditions with steel girder by using bolts considering a rational and economical method of connection and compared with the results of FEM analysis. From the experimental result, if the bolts are strong enough to resist shear force between the FRP bridge deck and the steel girder, it will be structurally secure to use the zigzag method.

• International Journal of Highway Engineering
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• v.20 no.1
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• pp.147-156
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• 2018

PURPOSES : The purpose of this study is to analyze the characteristics of the weight values of evaluation items by traffic safety project type. METHODS : In general, a large-scale investment in projects such as the traffic safety project requires economic analyses to be performed in advance. However, there is an argument for considering special characteristics of the traffic safety project. Therefore, this study conducted characteristic analysis of the weight values of evaluation items. The analysis consisted of two steps. The first step was hypothesis verification using analysis of variance (ANOVA). In this process, the authors examined whether the weight of evaluation items is the same regardless of the traffic safety project type. Based on the first step's results, the authors proceeded to the second step. The objective of this step was to analyze how different the weight values are by traffic safety project type using an analytic hierarchy process. RESULTS : According to the ANOVA test results, the benefit to cost ratios have different weight values based on traffic safety project type at the 0.01 significance level. The policy evaluation items, such as the plans connection, resident opinion, and regional equity, also showed the same results except that the result for the related plans connection was statistically significant at the 0.05 level. Based on the first step's result, the AHP analysis in the second step showed that the traffic safety projects for vulnerable users and pedestrians have very low weight values in economic evaluation factors compared with other safety project types. The weight values for vulnerable users and pedestrians were 0.29 and 0.26, respectively, in economic evaluation items. On the other hand, the weight values for other safety project types were around 0.6. Among the policy evaluation items, resident opinion showed a higher weight value than other factors, such as connection and regional equity items. CONCLUSIONS : The social and economic impact of a traffic safety project varies by project type and project characteristics. Although the economic approach is overarching and a reasonable methodology is applied for large-scale projects, it should be noted that the safety issue, especially for transportation of vulnerable uses, requires a non-economical approach. Based on the analysis results, this study suggests that the priority of the projects should be determined by separating them into independent assessment groups depending on their characteristics.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.4
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• pp.82-90
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• 2009

Pneumatic cylinder is one of the low cost actuation sources which have been applied in industrial and prosthetic application since it has a high power/weight ratio, a high-tension force and a long durability However, the control problems of pneumatic systems, oscillatory motion and compliance, have prevented their widespread use in advanced robotics. To overcome these shortcomings, a number of newer pneumatic actuators have been developed such as McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle (PAM) Manipulators. In this paper, one solution for position control of a robot arm, which is driven by two pneumatic artificial muscles, is presented. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external load of the robot arm. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is proposed in this paper. This estimates the external load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external working loads.