• Journal of Advanced Marine Engineering and Technology
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• v.17 no.1
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• pp.26-32
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• 1993

The loads exerted on electro-hydraulic servo system are classified into inertial, viscous, and spring load. The additional load called disturbances is also exerted on system but is generally not modeled. To deal with these kinds of loads, it is necessary to maintain the continuous signal transfer, so we can construct compensator to satisfy control specifications using feedback signal such as displacement, velocity, acceleration and pressure known as state variables. In case of controlling the speed of hydraulic motor, we must keep up robust performance for the various loads and disturbances acted on the system. However, the load flow rate in the valve is characterized by nonlinearity so that traditional theory of linear control could not be expected to give the desired performance. In this paper, it is shown that speed controller of hydraulic motor gives a good command following and disturbance rejection performance by applying sliding mode theory as a way of robust control to the nonlinearity, variation of loads and disturbances.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.2
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• pp.87-92
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• 1986

The differential equation, which can determine the dynamic critical loads for low parabcoic arches, is derived in this study. The dynamic critical loads of the parabolic arches subjected to a concentrated step load are nummerically analyzed for the changes of load positions. In cases of arches with different end conditions (both hinged, fixed hinged, both fixed), the effect of end conditions and that of the rises are investigated in detail. The summary of the results are the following: 1)The snapthrough does not occur when the rise of arch is very low, and the bifurcation appears clearly as the rise of arch increases. 2)The regions in which the dynamic critical loads are not defined for the both ends fixed are broader than that for the both ends hinged. 3)For all case, the load positions of minimum dynamic critical loads exsit at the near position from the end hinged. Thus, the results obtained in present study show that the magnitude of dynamic critical loads, the load positions of minimum dynamic critical loads and the regions in which the dynamic critical loads are not defined depend on end conditions of arches.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.796-805
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• 1995

For the purpose of improving performances of a turbocharged diesel engine at low speed, this study investigates the effects of the injected air for the performances and flow characteristics in the intake and exhaust pipes by using the computer simulation with test bed. In the theoretical analysis, the whole flow system, including engine cylinders and intake and exhaust pipes, is calculated numerically by the method of filling and emptying. From the results of this study, the following conclusions may be summarized. Increasing injected air pressure into the pipe of compressor exit brings about the improvement in a performance and flow characteristics of intake and exhaust pipes under full load operating conditions at 1000 rpm of the engine speed, but shows trends of the inferior performances under no load operating conditions at 2000 rpm of the engine speed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.375-380
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• 2007

The goal of this paper is to develop a rational static method which consider efficiently the dynamic effect of the gravity load following sudden removal of element. For this goal this paper introduce the equivalent load for element stiffness which is a preceding research result and will develop equivalent static analysis which will be able to predict the maximum behavior considering dynamic effect. Some examples are provided to verify it. Equivalent static analysis is compared with the analysis method which is recommended by the GSA2003 guidelines and the time-history analysis which is the most accurate for dynamic behavior.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3051-3053
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• 1999

In recent years, it becomes a worldwide trend that the power utilities focus their attention to Demand Side Management. Increasing Electric power consumption, they adopt a direct load management to accomplish low cost and stability of electric supply. Following this trend, KEPCO is researching a Direct Load Control System for Air Conditioner. This Paper presents the development results of the Direct Load Control System to Control electric power consumption of Conditioner in summer period this year.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.1
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• pp.93-100
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• 2000

The purpose of this study is to investigate the shear behavior of reinforced concrete beams according to small shear span-depth ratio between a/d=1.5, 2.8, 3.6. In general, shear strength of reinforced concrete beams is dependent on the compressive strength of concrete the longitudinal steel ratio, the shear span-depth ratio and shear reinforcement. The static test was carried out to measure the ultimate load, the initial load of flexural and diagonal cracking, crack patterns, fracture modes. The load versus strain and load versus deflection relations were obtained from the static test. The test results on shear strength were compared with results obtained by the formulas of ACI code 318-95. The shear strength of reinforced concrete beams exceeded those predicted following present ACI code 318-95(11-6).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.133-142
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• 1992

A kineamatic nonlinear multivariable laundher is modeled of which the azimoth and elevation axes are drived simultaneously and SISO and MIMO LQG/LTR controllers are designed and evaluated for this system. Also, the suitable command input function is suggested for the desired command following performance and the LQG/LTR control system with disturbances and load variation is evaluated for the entire operating range by computer simulation. It is found that the linear SISO LQG/LTR controller can be used for the kinematic nonlinear multivariable launder in the entire operating range and is effective for disturbance rejection and load variation.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.2
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• pp.111-118
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• 2006

In this thesis, we analyze the efficiency of the algorithm to distribute the load in the clustered system, by comparing with the existed algorithm. PWLC algorithm detects each server's load in the system at weighted period, and following the detection of the loads, a set of weights is given to each server. The system allocates new loads to each server according to its weight. PWLC algorithm is compared with DWRR algorithm in terms of variance, waiting time by varying weighted Period. When the weighted period is too short, the system bears a heavy load for detecting load over time. On the other hand, when the weighted period is too long, the load balancing control of the system becomes ineffective. The analysis shows PWLC algorithm is more efficient than DWRR algorithm for the variance and waiting time.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.414-420
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• 2003

The domestic needs for larger capability of power sources are increasing to cope with the expanding power load which results from the industrial developments & the progressed life style. In summer, the peak load is mainly due to the non-industrial reasons such as air-conditioners and other cooling equipments. To cover the concentrated peak load in stable, the power transmission lines should be more constructed and efficiently operated. The ampacity design of the underground cable system is generally following international standards such as IEC287, IEC60853 and JCS168 which regards the shape of 100% daily full power loads. It is not so efficient to neglect the real shapes of load curves generally below 60~70% of full load. The dynamic (real time) rating system tends to be used with the measured thermal parameters which make it possible to calculate the maximum ampacity within required periods. In this paper, the CTM(Conductor Temperature Monitoring) which is the base of dynamic rating systems for tunnel environment is proposed by a design of lumped thermal network ($\pi$-type thermal model) and distribution temperature sensor attached configuration, including the estimation results of its performances by load cycle test on 345kV single phase XLPE cable.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.146-155
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• 2011

Sustainable building is getting more and more important topic in 21C. Following this trend, building energy saving standard has been reinforced in Korea. Especially, insulation standards are revised continuously after1979. This study aims to evaluate the correlation between the revised insulation standards and heating and cooling loads of a residential building. This study shows that the standard of insulation is more related with heating load than cooling load, and cooling load is more related with other sources such as glass types and solar incidence through windows. In case of highly-insulated building such Passive Houses or Zero Energy Houses, the cooling load should also be considered as important as heating load when revising the building energy saving regulations in the future.