• Journal of Institute of Control, Robotics and Systems
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• v.3 no.4
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• pp.422-434
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• 1997

In this paper, a two-stage kinematic optimal design for a 3 degree of-freedom (DOF) excavator subsystem, which consists of boom, arm and bucket, is performed. The objective of the first stage is to find the optimal parameters of the joint-actuating mechanisms which maximize the force-torque transmission ratio between the hydraulic actuator and the rotating joint. The objective of the second stage is to find the optimal link parameters which maximize the isotropic characteristic of the excavator subsystem throughout the workspace. It is illustrated that kinematic/dynamic performances of the kinematically optimized excavator subsystem have improved compared to those of original HE280 excavator, with respect to three performance indices such as maximum load handling capacity, maximum velocity capability, and acceleration capability.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.71-78
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• 2004

The loader of this study is an agriculture machine for a stock farmer. We has much researched about power train and steering system in order to develop a new stock machine. So, the loader developed in this study has a 4 wheel driving system and a 4-type wheel steering system. Though the technological region is some large and general, these technologies are very important and their technical life may be very long. The power train of the loader is consisted of many units as follows, engine, clutch, transmission, and axles. And, the 4-type wheel steering system is consisted of oil tank, oil pump, steering valve, solenold valve, electronic controller, hydraulic cylinders, and touch sensors. This study shows construction logics of power train and steering system. We could know from many working tests that the developed loader with 4-type steeling system has many advantages when driving in a narrow corral.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.835-840
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• 2000

The objective of the present study is to investigate the characteristics of pressure wave propagation of viscous fluid flow in a circular pipe line. The goal of this study is to select the best frequency of each control factor of a circular pipe. We intend to approach a formalized mathematical model by a very exact and reasonable polynomial for fluid transmission lines. and we computed this mathematical model by computer. The results show that the oil viscosity decreased as the length of the circular pipe increases. and The energy of pressure wave propagation decreased as the pipe diameter decreases. The factor is that density of oil was changed resonant frequency. It has been found the viscosity characteristics is changed largely by length of hydraulic pipe and volume of cavity tank.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.617-622
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• 1994

In this paper, we perform a two-stage, kinematic optimal design for 3 degree-of-freedom excavator system which consists of boom, arm, and bucket. The objective of the first stage is to find the optimal joint parameters which maximize the force-torque transmission ratio between the hydraulic actuator and the rotating joint. The objective of the first stage is to find the optimal link parameters which maximize the isotropic characteristic throughout the workspace. It is illustrated that performances of the optimized excavator are improved compared to those of HE280 excavator, with respect to the described performace index and maximum load handling capacity.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.66-71
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• 2002

파워시프트는 동력전달의 단속 없이 변속할 수 있는 변속 방식이다. 기어는 동기 물림식으로 되어 있으며, 유압 클러치를 통하여 주행 중에도 동력의 흐름을 제어할 수 있다. 주요 구성 요소는 동력 흐름을 제어할 수 있는 유압 클러치와 동력을 전달하는 기어 조합이며, 유압 클러치는 피스톤, 리턴 스프링, 디스크, 플레이트 등으로 구성되어 있다. 접속 시에는 유압 피스톤이 리턴 스프링을 압축하며 전진하여 플레이트와 디스크에 수직력을 가하고 이를 결합시켜 동력을 전달한다. 해제 시에는 리턴 스프링에 의하여 피스톤이 후퇴하고 동력이 차단된다. 이때 유압 제어 시스템은 최대 견인 부하에서도 변속을 원활하게 하기 위하여, 클러치 압력을 이용해 변속 중 작동 클러치의 토크를 정교하게 제어한다. (중략)

• Water for future
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• v.12 no.2
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• pp.49-55
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• 1979

The purpose of this study is to develope the computer program to compute the unsteady, transient flow conditions in a hydraulic system. The unstready flow condition may be brought about due to power failure to pump motors, pump start-up or modulation of control valve. The program was written specially for analyzing the water-hammer in the pumping system. The pumping system which can be simulated by the program can contain pipelines, tunnel, surge tanks, branched lines, reservoirs, dead end pipes and valve controls. The use of a computer program to analyze haydranlic transients is of great benifit to the designers of transmission main and distribution systems. Advantages include time savings, the ability to analyze complex piping systems, and increased accuracy. The author outlines a pogram developed for the above system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.284-294
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• 1996

In this paper, dynamic characteristics of an AT clutch system were investigated considering the dynamics of check ball and hydraulic control valves. Dynamic model of a pressure control solenoid valve (PCSV) was obtained by Bondgraph and permeance method. Also, the clutch piston and check ball dynamics were modeled by considering the effect of centrifugal force of the oil entrapped in the clutch chamber. In order to validate the dynamic models obtained, plunger displacement of PCSV and pressure response of the clutch supply lines were compared with the available experimental data, which were in good accordance with the numerical results. Using the dynamic model of the clutch system, simulations were performed to investigate the effect of the rotational speed on the response of clutch cylinder pressure, clutch piston and check ball displacement, and oil flow rate into the cylinder and flow rate out of the check valve.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.113-118
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• 2002

Wave overtopping is one of the most important hydraulic responses of breakwater because it significantly affects its functional efficiency, the safety of transit and mooring on the rear side, wave transmission in the sheltered area, rear side armor stones and to some extent, the structural safety itself. The hydrodynamic characteristics of low crest breakwater by the overtopping rate can be summarized as follows: 1. It is better to use maximum overtopping rate than to use mean overtopping rate for design of coastal structures. 2. Maximum overtopping rate was increase with wave steepness (between 0.01 and 0.02). 3. Overtopping rate is decreased when relation length of berm was over wave length.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.8
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• pp.917-923
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• 1999

This paper proposes an efficient method of hydro-thermal scheduling in coordination with head variation and hydraulically coupled plants using Evolutionary Programing(EP). Based on the EP technique, the proposed algorithm is capable of determining the global optimal solutions. The constraints such a power balance condition, water available condition and transmission losses are embedded and satisfied throughout the proposed EP approach. The effectiveness of the proposed approach is demonstrated on the test systems and compared to those of other method. The results show that the new approach obtains a more highly optimal solutions than the conventional other methods such as newton-raphson method, Dynamic Programming(DP), LU factorization.

• Water for future
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• v.29 no.1
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• pp.249-263
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• 1996

Presented herein are the results of a laboratory study on structural loads (icing weight and wind loads) associated with icing formation on rigidly fixed, circular power-transmission cables and cylinders. The experiments were carried out using movable wind tunnel under two different conditions: refrigerated and non-refrigerated conditions. Temporal evolution of icing loads were determined in the refrigerated laboratory and wind loads for icings at several stages of icing formation were measured in the non-refrigerated laboratory.