• Journal of Institute of Control, Robotics and Systems
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• v.21 no.5
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• pp.427-433
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• 2015

Hot forging industry workers are prone to encounter several health risks due to lack of automation and poor working environment conditions. These workers particularly suffer from muscle fatigue owing to the constant handling of heavy products during the forging process. Thus we developed an assistant robot for workers who carry out hot forging tasks. The purpose of a robot is to compensate gravity-loads for heavy products. To verify the functionality of a robot, we performed a muscle fatigue analysis using Electromyography (EMG) signals. Four muscles of the upper extremity were chosen to measure muscle activity. And experiment conditions were setup to imitate the hot forging process. Post experimental analysis of the captured muscle activity revealed a reduction in the median frequency of the EMG signals, which means clear fatigue reduction due to a robot's assistance. The developed assist robot with compact and economical components can be efficiently utilized at forging work sites to create better working conditions for operators.

• Women's Health Nursing
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• v.16 no.2
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• pp.204-214
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• 2010

Purpose: This study was done to determine the level of awareness and self-efficacy and their relationships to osteoporosis among young women. Methods: The participants were 309 young women living in Seoul. The data were collected using questionnaires from July to September 2009. The Osteoporosis Awareness Scale consists of five areas with a total of 31 questions and the Self-efficacy Scale consists of 18 questions. Data were analyzed using descriptive analysis, t-test, ANOVA, Scheffe' test and Pearson's correlation coefficients. Results: The average level for osteoporosis awareness was 2.22, of a possible 4.00 and significant difference were related to participants' previous encounter with any information about osteoporosis, behavior to prevent osteoporosis, experience of weight control, and frequency of vegetable and calcium-rich foods intake. The average level of self-efficacy for osteoporosis was 2.81, of a possible 4.00 and significant difference related to participants' educational level, occupation, behavior to prevent osteoporosis, smoking, method of weight control, regular exercise, and frequency of vegetable and calcium-rich foods intake. There were significant positive correlations among awareness and self-efficacy about osteoporosis. Conclusion: This study suggests that health care professionals need to provide effective interventions for young women to enhance their osteoporosis awareness and self-efficacy for preventing osteoporosis.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.82-98
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• 1994

A mathematical model for the hydrodynamic forces acting on the ship manoeuvring in waves is formulated and a numerical method for the problem is developed. The motion of a ship, which manoeuvres in waves, may be thought to have two components; one is a high frequency component due to encounter waves, and the other is a low frequency component due to manoeuvring motion. So the method of two time scale expansion is used to divide linear boundary value problem. For the effects of waves on the manoeuvring motion of a ship, only the second order drift forces are considered. The integral equation for the velocity potential is solved by 3 dimensional panel method and hydrodynamic forces are calculated by direct integral method.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.381-386
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• 2006

In dielectric waveguide analysis and synthesis, we often encounter an awkward task of solving the eigenvalue equation to find the value of propagation constant. Since the dispersion equation is an irrational equation, we cannot solve it directly. Taking advantage of approximated calculation, we attempt here to solve this irrational dispersion equation. A new type of eigenvalue equation, in which guide index is expressed as a function of frequency, has been developed. In practical optical waveguide designing and in calculating the propagation mode, this equation will be used more conveniently than the previous one. To expedite the design of the waveguide, we then solve the eigenvalue equation of a slab waveguide, which is sufficiently accurate for practical purpose.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.193-196
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• 2002

The relativistic theory has not been properly taken up by the marine hydrodynamicists. To take on a relativistic view, we confine ourselves to a simple vector case of a wave train in spacetime, to be shown to represent a sound wave or a surface wave, and bring in an observer who is travelling on another platform. We are interested in relative position of each event on these two worldlines. It, then, will be shown that the velocity, the acceleration, the encounter frequency, the group velocity, and the time and the space distance between the wave and the observer on the worldlines should all be derivable in principle. This is interpreted to mean that we really have the relativistic events taking place with different values of time dilation in the sense of 'spacetime', and that the well-known ${\lceil}special Theory of Relativity{\rfloor}$ applies just as well in hydrodynamic waves.

• Journal of Agricultural Extension & Community Development
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• v.18 no.3
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• pp.631-664
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• 2011

As agricultural companies encounter number of risks in their business, it is very important to control the risks for their stable management. So we examine the agricultural business risks and propose the risk management strategies for the agricultural companies. For these purpose, we analyze the agricultural business risks with which agricultural companies are confronted, and propose the agricultural companies' the risk management strategies. The results of this study are as follows : First, Changing the risk environment of agricultural business, we have to realize the importance of the agricultural risks and risk management in it. Second, When we choose the risk management strategies which are risk retention, risk avoidance, risk control, risk transfer and insurance, etc., we should always consider the frequency of loss and the severity of loss. Third, If we don't control the agricultural risks, we will be in a position to very difficult situation. So, Agricultural companies should lead to stronger effort to manage the risks for their stable business.

• Journal of Korean Institute of Industrial Engineers
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• v.18 no.1
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• pp.37-45
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• 1992

Common assumption we frequently encounter in early models of software reliability is that no new faults are introduced during the fault removal process. In real life, however, there are situations in which new faults are introducted as a result of imperfect debugging. This study alleviating this assumption by introducting the probability of perfect error-correction is an extension of Littlewood's work. In this model, the system reliability, failure rates, mean time to failure and average failure frequency are obtained. Here, when the probability of perfect error-correction is one, the results appear identical with those of the previous studies. In the respect that the results of previous studies are special cases of this model, the model developed can be considered as a generalized one.

• Journal of Biosystems Engineering
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• v.27 no.5
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• pp.391-398
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• 2002

During handling unitized products, they are subjected to a variety of environmental hazards. Shock and vibration hazards are generally considered the most damaging of the environmental hazards on a product and it may encounter while passing through the distribution environment. A major cause of shock damage to products is drops during manual handling. The increasing use of unitization of pallets has been resulted in a reduction of the shock hazards. This has caused an increasing interest in research focused on vibration caused dam age. Damage to the product by the vibration most often occurs when a product or a product component has a natural frequency that falls within the range of the forcing frequencies of the particular mode of transportation being used. Transportation vibration is also a major cause of fruit and vegetable quality loss due to mechanical damage. This study was conducted to determine the vibration characteristics of the corrugated fiberboard bones for packages of pears, and to investigate the degree of vibration injury of the pears in the boxes during the simulated transportation environment. The vibration tests were performed on an electrohydraulic vibration exciter. The input acceleration to exciter was fixed at 0.25 G for a single container resonance test and 0.5 G for the vertical stacked container over the frequency range from 3 to 100 Hz. Function generator (HP-33120A) was connected by wire to the vibration exciter for controlling the input acceleration at a continuous logarithmic sweep rate of 1.0 octave per min. The peak frequency and acceleration on the single box test were 22.02 Hz, 1.5425 G respectively, and these values on the vertical stacked boxes were observed from the bottom box 19.02, 18.14, 16.62 and 15.40 Hz and 2.2987, 3.7654. 5.6087, and 7.9582 G, respectively. The pear in the bottom box had a slightly higher damage level than the fruit packed in the other stacked boxes. It is desirable that the package and transportation system has to be so designed that 15∼20 Hz frequency will not occur during the transportation environment.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.1
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• pp.83-95
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• 1998

Interest in weekend farming has been increasing recently among city-dwellers although it is still only in the beginning stages. Weekend farming has been increasing recently among city-dwellers although it is still only in the beginning stages. Weekend farms provide people with new activities and also help to preserve green areas within the city. It is necessary to understand what weekend farm users think and what problems they encounter in order to increase the use of these farms. For this reason, we studied 16 weekend farms in Seoul managed by the Rural Guidance Office and the Agricultural Cooperative. We distributed 24 questionnaires by hand and these were later returned by mail. The questionnaire asked weekend farmers about their motivation for using the farms, about their motivation for using the farms, frequency of use, level of satisfaction, current state of housing and the sort of plants they cultivated, among other things. We found that most of them live in apartments and have little access to green areas,. Weekend farm users were generally satisfied. However, they had a lack of gardening knowledge and reported that facilities such as toilets and water service were unsatisfactory. Political support is needed from the government in order to improve weekend farms. There needs to be a wider range of farm sizes and an increase in the uses of the farms. If these improvements occur, investment in and the development of weekend farming will increase and weekend farms will take root in Korea.

• Journal of Advanced Research in Ocean Engineering
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• v.1 no.4
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• pp.252-267
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• 2015

Offshore structures might encounter several environmental and operating conditions during their lifetime of several decades. In order to predict the dynamic behavior of offshore structures, several simulation cases should be considered to deal with all the combinations of ocean environments and operating conditions. Because a sophisticated time-domain coupled dynamic analysis requires an extremely large amount of computational time to handle all the possible cases, an efficient preliminary process to prescreen the probability of severe environmental conditions can be helpful in downsizing the number of simulation cases and computational effort. In this study, a prescreening procedure to reduce the number of environmental conditions for dynamic analyses of offshore structures is proposed. For the efficiency of the procedure, frequency-domain theories were adopted to estimate the platform offset, using quasi-static analyses in line tension prediction. The results were validated by comparing with those of dynamic analysis coupled between platform and mooring lines, and reasonable agreement was observed. In addition, the characteristics of environmental conditions classified to be severe to the system were investigated through the application of the developed prescreening scheme to several actual environmental conditions.