• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.116.1-116
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• 2002

When the teleoperated system has a signal transmission time delay between slave and control system , the system stability as well as the position tracking and the force reflecting performances are likely to be deteriorated. This paper proposed a bilateral control scheme and a controller design method for the teleoperated control systems with a signal transmission time delay. The proposed controller is a modified type of smith predictor for the time delay in each input and output stage of an open loop unstable plant. The proposed controller not only satisfies the system internal stability but also improves the position tracking performance with disturbance rejection capability. The simulation...

• Structural Engineering and Mechanics
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• v.22 no.6
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• pp.741-759
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• 2006

A general theory which describes the elastic response of a curved anisotropic plate subjected to stretching and bending will be developed by considering the nonlinear effect that reflecting the non-flat geometry of the structure. By applying a newly derived $6{\times}6$ matrix constitutive relation between force resultants, moment resultants, mid-plane strains and deformed curvatures, the governing differential equations for a curved anisotropic plate is developed in the usual manner, namely, by consideration of the constitutive relation and equilibrium equations. Solutions are obtained for simply-supported boundary conditions and compared to corresponding solutions that neglecting the nonlinear effect in the analysis. The comparisons indicate that the nonlinear terms in the equations that caused by the curvature of the structure is crucial for the curved plate analysis. Under certain curved plate geometries the unreasonable results will be induced by neglecting the nonlinear effect in the analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.78-83
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• 2007

The paper focuses on the establishment of optimized bucket path planning and trajectory control designated for force-reflecting backhoe reacting to excavation environment, such as potential obstacles and ground characteristics. The developed path planning method can be used for precise bucket control, and more importantly for obstacle avoidance which is directly related to safety issues. The platform of this research was based on conventional papers regarding the kinematic model of excavator. Jacobian matrix was constructed to find optimal joint angles and rotation angles of bucket from position and orientation data of excavator. By applying Newton-Raphson method optimal joint angles and bucket orientation were derived simultaneously in the way of minimizing positional errors of excavator. The model presented in this paper was intended to function as a cornerstone to build complete and advanced path planning of excavator by implementing soil mechanics and further study of excavator dynamics together.

• Nuclear Engineering and Technology
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• v.35 no.3
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• pp.214-225
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• 2003

A teleoperated manipulator system has been developed for remote handling of the spent fuel bundles. A heavy-duty power manipulator with high reduction ratio joints is used for the slave manipulator in the developed system since the handling tasks of the spent fuel bundles need power. Also, the universal type master manipulator, which has force reflecting capability, is used for precise remote manipulation. The power manipulators so frequently occur the control input saturation that the precise control performances are not achieved due to the windup phenomenon. An advanced bilateral control scheme compensating for the saturation is applied to the teleoperated manipulator system. The validity of the developed system is verified by the grid cutting and fuel transportation tasks from the mockup spent fuel bundle.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.7
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• pp.578-585
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• 2000

This paper presents a robust and systematic bilateral controller design method for a teleoperation of an underwater manipulator. Disturbance observer is used as a local controller of the master and underwater slave manipulator to set up the teleoperation system as a nominal model by compensating coupled nonlinear terms model uncertainties and external disturbances in the water. Using the linearized master/slave model a $H_{\infty}$ optimal control scheme is applied to systematically construct a force reflecting bilateral controller.

• Advances in concrete construction
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• v.13 no.6
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• pp.423-431
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• 2022

Although the influence of moisture content on the mechanical properties of concrete has been studied for a long time, research related to its influence on the damping and energy dissipation property of concrete structure is still very limited. In this paper, the relationship between damping property and moisture content of concrete using cyclic uniaxial compression is firstly presented, and the mechanism of the influence of moisture content on concrete damping and energy dissipation capacity is analyzed. Based on the experimental research, moisture-related damping and energy dissipation model is proposed. Results show that the dissipated energy of concrete and loss factor increase as the moisture content increasing. The energy dissipation coefficient reflecting the influence of stress level of concrete under cyclic load, decreases first and then increases as the moisture content increasing. The mechanism of moisture-related energy dissipation behavior can be divided into the reactive force of water, the development of the internal micro cracks and the pore water pressure. Finally, the proposed moisture-related damping and energy dissipation model are verified.

• Fashion & Textile Research Journal
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• v.9 no.1
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• pp.15-23
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• 2007

In the Middle Ages it was customary to cover up the hair, but the Renaissance brought uncovered coiffures with the revival of humanism. In those days, silk and linen veil, ribbon, string of pearl used for covering, wrapping round with the hair. During the Baroque period, the style of hair was to pursue the beauty of imbalance in form, reflecting the atmosphere of the time. Hurluberlu and Fontanges hairstyles were in fashion. Then in the Rococo period, huge, resplendent coiffures of exquisite beauty were invented as a symbol of power, and these modes of hairdo were a dominant force in the culture of personal adornment of that time. Pouf and enfant hairstyles were in fashion. As a reaction against the extravagance of the proceding modes, late 18th and early 19th centuries brought revival of simpler hairstyles of ancient Greece and Rome by the influence of neoclassicism. The latter half of the 1820's onwards saw he reappearance of voluminous coiffures as well as an enormous variation of knots with combinations of false knots and chignons. Late 19th through early 20th centuries was the period of beautifully waved hair, the style of which was an integration of Marcel waves and Art Nouveau. The 20th century saw the epoch-making invention of permanent waves using electricity. Concurrently, with an increasing participation of women in social affairs since pre-and post-World War I periods, as well as with Art Deco in full flourish, bobbed hair was created in pursuit of lightness and nimbleness, quickly showing the change of women's modes of life. Hair fashions thoroughly embody the aesthetic sense of each period, reflecting the landscape of contemporary society.

• Journal of Navigation and Port Research
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• v.33 no.9
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• pp.645-651
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• 2009

In this study, a series of laboratory experiments were carried out to investigate the weak reflection of regular and random water waves over a train of protruded permeable shore structures. A cylindrical slit type breakwater and the alternatives are employed and compared for reflecting and transmitting capabilities of incident waves including wave forces. A series of random waves were generated by using the Bretschneider-Mitsuyasu frequency and directional spectrum. Measured spectrum of irregular waves without breakwaters is verified by comparing with those of the input waves generated. Weak reflection is occurred at the breakwater center of the peak frequency. If the row of breakwaters is fixed at three layers and the relative height of breakwater is fixed at 0.6, around 45% of incident wave energy is reflected to offshore. It is also found that the transmission of directional random waves increases as the maximum frequency parameter increases. A very good agreement is observed. Reflection coefficients of permeable submerged breakwaters are less than those of impermeable breakwaters. The upside-down L shape is recommended for a small fishery harbor mooring in terms of reflecting capability and of practical application. The final design was applied to the wharf of a small beach of Seolly, near Namhae at the southeast coast of Korea.

• Korea journal of population studies
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• v.21 no.2
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• pp.5-36
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• 1998

This study examines the change of female labor market structure during the last several decades, focusing the effects of demographic factors such as declining fertility and increasing educational attainment of women. Women of the recent cohort tend to postpone their first marriages, to attain higher levels of education, and to have smaller number of children than women of the old cohort. This demographic trend results in the change of the population compositions in a way that population subgroups with high labor force participation have been increased. In addition, women of each population subgroup supply their labor in the market with higher rate than their old cohort counterparts. The labor force participation rate of highly educated women, and of married women has been increased faster than that of women with low education and of unmarried women. Although childbirth is still one of the most critical barrier for the women's participation, more and more women with young children tend to work for pay than ever before. In spite of the demographic change which is supportive to the increasing labor force participation, the Korean labor market have lost its female participants for the last year of the economic restructuring, reflecting demand-side factors as well as demographic factors are essential to determine the labor force participation of women.

• Korea journal of population studies
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• v.9 no.1
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• pp.41-53
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• 1986

The purpose of this paper is two-fold. One is to investigate the determinants of the demand supply of labor, and another is to project long-term demand and supply of labor. The paper consists of three parts. In the first part, theoretical models and important hypotheses are discussed: for the case of a labor supply model, issues regarding discouraged worker model, permanent wage hypothesis, and relative wage hypothesis are examined and for the case of a demand model, issues regarding estimating an employment demand equation within the framework of an inverted short-run produc- tion function are inspected. Particularly, a theoretical justification for introducing a demographic cohort variable in a labor supply equation is also investigated. In the second part, empirical results of the estimated supply and demand equations are analyzed. Supply equations are specified differently between primary and secondary labor force. That is, for the case of primary labor force groups including males aged 25 and over, attempts are made to explain the variations in participation behavior within the framework of a neo-classical economics oriented permanent wage hypothesis. On the other hand, for the case of females and young male labor force, variations in participation rates are explained in terms of a relative wage hypothesis. In other words, the participation behavior of primary labor force is related to short-rum business fluctuations, while that of secondary labor force is associated with intermediate swings of business cycles and demographic changes in the age structure of population. Some major findings arc summarized as follows. (1) For the case of males aged 14~19 and 2O~24 groups and females aged 14∼19, the effect of schhool enrollment rate is dominant and thus it plays a key role in explaining the recent declining trend of participation rates of these groups. (2) Except for females aged 20∼24, a demographic cohort variable, which captures the impact of changes in the age structure on participation behavior, turns out to show positive and significant coefficients for secondary labor force groups. (3) A cyclical variable produce significant coefficients for prime-age males and females reflecting that as compared to other groups the labor supply behavior of these groups is more closely related to short-run cyclical variations (4) The wage variable, which represents a labor-leisure trade-off turns out to yield significant coefficients only for older age groups (6O and over) for both males and females. This result reveals that unlike the experiences of other higer-income nations, the participation decision of the labor force of our nation is not highly sensitive with respect to wage changes. (5)The estimated result of the employment demand equation displays that given that the level of GNP remains constant the ability of the economy to absord labor force has been declining;that is, the elasticity of GNP with respect to labor absorption decreasre over time. In the third part, the results of long-term projections (for the period of 1986 and 1995) for age-sex specific participation rates are discussed. The participation rate of total males is anticipated to increase slightly, which is contrary to the recent trend of declining participation rates of this group. For the groups aged 25 and below, the participation rates are forecast to decline although the magnitude of decrease is likely to shrink. On the other hand, the participation rate of prime- age males (25 to 59 years old) is predicted to increase slightly during 1985 and 1990. For the case of females, except for 20∼24 and 25∼34 age groups, the participation rates are projected to decrease: the participation rates of 25∼34 age group is likely to remain at its current level, while the participation rate of 20∼24 age group is expected to increase considerably in the future (specifi- cally, from 55% in 1985 to 61% in 1990 and to 69% in 1995). In conclusion, while the number of an excess supply of labor will increase in absolute magnitude, its size as a ratio of total labor force is not likely to increase. However, the age composition of labor force is predicted to change; that is, the proportion of prime-age male and female labor force is projected to increase.