• Journal of Drive and Control
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• v.14 no.3
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• pp.8-17
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• 2017

With automobiles sharply increasing in numbers worldwide, we are faced with critical social issues such as traffic accidents, traffic jams, environmental pollution, and economic inefficiency. In response, research on ITS is promoted mainly by regions with advanced automotive industry such as the U.S., Europe, and Japan. While Korea is working on moving forward in the global market through developing and turning to global standards systems related to ASV (Advanced Safety Vehicle), the country is not fully prepared for such projects. The purpose of ACC (Adaptive Cruise Control) is to control a vehicle's longitudinal speed and distance and minimize driver workload. Such a system should be valuable in preventing accidents, as it reduces driver workload in the 21st-century world of telematics created by development of the automobile culture industry. In this light, the thesis presents a method to test and evaluate ACC system and a mathematical method to assess distance. For the proposed test and evaluation, theoretical values are tested with vehicle test and a database is acquired, by using vehicles equipped with an ACC system. Theoretical evaluation criteria for developing ACC system may be used and scenario-specific evaluation methods may find useful application through testing the formula proposed by comparing the database and mathematical method.

• Journal of Drive and Control
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• v.15 no.2
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• pp.22-31
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• 2018

This study deals with verifying the design feasibility, of an independently driving hydraulic system for disaster response purposes, through an analytical approach. The development target is a system in which four traveling motors are driven independently, and must be easy to operate even under conditions in which different loads are applied to the traveling motors. In order to be suitable for complex work, the hydraulic system was designed using the main control valve with a pressure compensation function. If we can develop an analytical model that reflects the specifications and functions of the parts through the analysis program, we can verify the validity of the design before we make the prototype. The purpose of this study therefore, is to verify the feasibility of designing an independent drive hydraulic system through the development of an analysis model from the viewpoint of complex work. The analysis program uses Simulation X.

• Journal of Drive and Control
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• v.15 no.2
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• pp.1-8
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• 2018

This study is a first step toward reducing surge pressure, and it has another purpose, which is to developing an analysis model which can closely analyze a hydraulic circuit and be used in design. For development of analysis model, SimulationX, a commercial program, is used. The study progress methods are as follows. By analyzing the structure and operating mechanisms of each part of the hydraulic system of the pump truck and referring its parameters, develop a single component model. Assemble the developed single component model, and make an overall analysis the model. By comparing the similarities between the developed model and the actual system's test results, validate the reliability of the analysis model.

• Journal of Drive and Control
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• v.15 no.2
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• pp.46-51
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• 2018

Many research studies have been carried out related to saving energy and environmental pollution in the field of construction machinery. The best solution for reducing the related environmental pollution is to reduce fuel consumption by upgrading the energy efficiency of machinery used in this field. An efficiency upgrade in the field of construction machinery would mean minimizing the pressure loss in hydraulic pipe lines or achieving optimal operating conditions while responding to a load. One way to achieve this is to make an equivalent circuit, like an electrohydrostatic actuator, or to improve the spool type valve using the 4/3 way method. This study deals with an electrohydraulic proportional flow control valve. SimulationX software is used as a simulation tool for analyzing the dynamic characteristics. The analysis results, including the performance and characteristics of design parameters, are discussed and the validity of the theoretical analysis is also evaluated.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.1
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• pp.8-14
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• 2015

Transmission of a tracked vehicle designed for multiple functions such as steering, gear-shifting, and braking is a core component of heavy vehicle to which the power is transferred based on combined technology of various gears, bearing, and fluid machineries. Robustness and durability of transmission, however, have been issued due to a large number of driving units and sub-components inside its body. Particularly, transmission housing is important structure which supports the transmission, and is made of aluminum alloy. Thus, structural robustness against such mechanical loading or vibration must be attained. Structural reliability evaluation through FEM analysis can save time and cost of the actual tests. In this study, structural evaluation is conducted on output housing of transmission, which is core component of tracked vehicle, using the simulation program. In addition, transmission dynamo test is performed to evaluate structural robustness of the output housing against the vibration which can be produced during the transmission operation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.300-303
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• 2010

The present study investigates the flow characteristics of simulant gel propellant(carbopol 0.5%wt) in a variety of injectors. Rheological data for gel propellant has been measured and injector flow characteristics for plain-orifice, chamfered-orifice and venturi type injector have been numerically analyzed. The apparent viscosity of plain-orifice and chamfered-orifice have tendency to increase along axial direction, whereas for venturi type injector, low viscosity has been achieved in the injector flow. This phenomenon was clearly pronounced as Reynolds number is increased.

• Steel and Composite Structures
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• v.20 no.1
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• pp.205-225
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• 2016

In this study the finite element method is utilized to predict the deflection and vibration characteristics of rectangular plates made of saturated porous functionally graded materials (PFGM) within the framework of the third order shear deformation plate theory. Material properties of PFGM plate are supposed to vary continuously along the thickness direction according to the power-law form and the porous plate is assumed of the form where pores are saturated with fluid. Various edge conditions of the plate are analyzed. The governing equations of motion are derived through energy method, using calculus of variations while the finite element model is derived based on the constitutive equation of the porous material. According to the numerical results, it is revealed that the proposed modeling and finite element approach can provide accurate deflection and frequency results of the PFGM plates as compared to the previously published results in literature. The detailed mathematical derivations are presented and numerical investigations are performed while the emphasis is placed on investigating the effect of the several parameters such as porosity volume fraction, material distribution profile, mode number and boundary conditions on the natural frequencies and deflection of the PFGM plates in detail. It is explicitly shown that the deflection and vibration behaviour of porous FGM plates are significantly influenced by these effects. Numerical results are presented to serve as benchmarks for future analyses of FGM plates with porosity phases.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.446-453
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• 2000

The closed cycle diesel system is operated in closed circuit system where there is non air breathing with working fluid consisted of the combination of oxygen, argon and recycled exhaust gas for obtaining underwater or underground power sources. this study has been carried out to analysis the performance of closed cycle system by means of investigation on the combustion characteristics of diesel engine MTU8V183TE52 operating in open, semi-closed, and closed cycle modes. The combustion in closed mode starts a little bit earlier than in open cycle mode. The oxygen concentration and fuel consumption at 240kW closed cycle running are 21∼24% by volume and 77∼79kg/h, respectively. The maximum cylinder pressure and ignition delay time are investigated 110bar and 8.9degree. Also, The combustion simulation program has been studied to predict whether or not combustion. The results from numerical prediction for the basic, cylinder averaged quantities such as the cylinder pressure and the heat release showed excellent with the experimental data.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.363-367
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• 2015

In this study, a high performance Bubble Jet Loop Heat Pipe (BJLHP) was developed using the enhanced nucleate boiling surfaces in an evaporating section. A sintered tube and GEWA-T(Wieland) tube were used enhance nucleate boiling. The thermal performance of these BJLHP was compared with the conventional smooth tube BJLHP with an effective thermal conductivity. This experiment was conducted under the following conditions : working fluid, charging ratio and input power of R-141b, 50%vol., 75W and 100W, respectively. As a result, the effective thermal conductivity of BJLHP with a sintered tube in the evaporating section was 300% higher than the smooth tube BJLHP.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.161-166
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• 2012

Intravenous (IV) injection is widely used to supply Ringer solution directly into a vein in hospital. Generally, a passive injection method has been used, which causes the inconsistent flow rate of fluid and inappropriate control of injection time by a patient. It leads to an unnecessary nurse's overwork and decrement of IV injection's effect. To solve these problems, flow control infusion pumps have been developed. But because of relatively heavy weight and high price, its usage has been limited. In the present study, a new automatic IV injection system is developed. It is installed with a small pressing mechanism driven by a small electric motor to regulate the flow rate by pressing tube. Proportional integral derivative (PID) feedback control algorithm is applied to control the electric motor. The system is smaller in size and uses lower power than the existing commercial product. The newly developed system is also installed with networking capability, which enables monitoring the status of several automatic IV injection system at the same time.