• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.31-34
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• 2003

To trace the working point of pressure-fed rocket propulsion system, direct analogy model was suggested, by which propellant mass flow rate and combustion chamber pressure were calculated from propellant tank pressures, levels and flight acceleration. In this paper, the analysis of KSR-III flight test results was taken by example, and it can be described that working point transition tendency of pressure-fed rocket propulsion system can be calculated by this direct analogy model.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.810-815
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• 2003

This research is concerned with the development of an Internet-based robot system, which is insensitive to the unpredictable Internet time delay. For that purpose, a simple mobile robot system that moves in response to the user' direct control on the Internet has been built. The time delay in data transmission is a big problem for the construction of this kind of system. Therefore, the PPS (Position Prediction Simulator) is suggested and implemented to compensate for the time delay problem of the Internet. The simulation and experimental result show that the distance error can be reduced using the developed PPS.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1173-1177
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• 1990

Cerebellar Model Linear Associator Net(CMLAN), a kind of neuro-net based adaptive control function generator, was applied to the problem of direct inverse calibration of three and six d.o.f. POMA 560 robot. Since CMLAN autonomously maps and generalizes a desired system function via learning on the sampled input/output pair nodes, CMLAN allows no knowledge in system modeling and other error sources. The CMLAN based direct inverse calibration avoids the complex procedure of identifying various system parameters such as geometric(kinematic) or nongeometric(dynamic) ones and generates the corresponding desired compensated joint commands directly to each joint for given target commands in the world coordinate. The generated net outputs automatically handles the effect of unknown system parameters and dynamic error sources. On-line sequential learning on the prespecified sampled nodes requires only the measurement of the corresponding tool tip locations for three d.o.f. manipulator but location and orientation for six d.o.f. manipulator. The proposed calibration procedure can be applied to any robot.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.409-412
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• 2001

Identification of systems operating in closed loop has long been of prime interest in industrial applications. The fundamental problem with closed-loop data is the correlation between the unmeasurable noise and the input. This is the reason why several methods that work in open loop fail when applied to closed-loop data. The prediction error based approaches to the closed-loop system are divided to direct method and indirect method. Both of direct and indirect methods are known to be applied to the closed-loop data without critical modification. But the direct method induces the bias error in the experimental frequency response function and this bias error may deteriorates the parameter estimation performance

• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.3
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• pp.14-19
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• 2004

The Direct Drive Valve used in this study contains a pressure-feedback-loop in itself, then it can eliminate nonlinearity such as the square-root-term in flow rate calculation and the change of bulk modulus of hydraulic oil. In this study, assuming that the dynamic characteristic of the DDV is modelled as a first order lag system, an parameter identification method using the input data and the output data is applied to obtain DDV's mathematical model. Then, a state feedback controller was designed to implement the force control of hydraulic system, and the control performance was evaluated.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2006.06a
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• pp.123-128
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• 2006

We constructed a micro-patterning system that build patterns on a photoresist coated wafer using laser direct writing system. Confocal microscope system was adapted for real-time auto-focusing of the laser writing lens to generate lines of uniform width.

• Journal of Magnetics
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• v.16 no.4
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• pp.379-385
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• 2011

This paper presents an optimal design of a direct-drive permanent magnet synchronous generator for a small-scale wind energy conversion system. An analytical model of a small-scale grid-connected wind energy conversion system is presented, and the effects of generator design parameters on the payback period of the system are investigated. An optimization procedure based on genetic algorithm method is then employed to optimize four design parameters of the generator for use in a region with relatively low wind-speed. The aim of optimization is minimizing the payback period of the initial investment on wind energy conversion systems for residential applications. This makes the use of these systems more economical and appealing. Finite element method is employed to evaluate the performance of the optimized generator. The results obtained from finite element analysis are close to those achieved by analytical model.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.106-110
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• 2017

Due to the plasma applied from the outside, which acts as an etchant during the etching process, considerable heat is transferred to the wafer and a separate cooling process is performed to effectively remove the heat after the process. In this case, a direct cooling method using a refrigerant is suitable for cooling through effective heat exchange. The direct cooling method using the refrigerant using the latent heat exchange is superior to the cooling method using the sensible heat exchange. Therefore, in this paper, AMESim is used to design a direct refrigerant cooling system using latent heat exchange simulator was built.The constructed simulator is reliable compared with the actual experimental results. It is expected that this simulator will help to design and search for optimal process conditions.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.11
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• pp.171-180
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• 2019

This research proposed the Direct Construction System for construction corporations as a strategy intended to perform cause analysis of construction technician shortage matter and solve resulting problems, and in view of the outcomes from the application of this system to the projects and workshops, it was verified that unsteady employment, lack of career prospect, and conditions of work environment can be resolved. In addition, from corporations' perspective, it is considered that by clarifying the abovementioned three problems, fundamental complications of construction administration, quality control, safety supervision, and cost management were settled, concluding forthcoming advancement of domestic construction business quality fell far behind developed counties.

• Journal of ILASS-Korea
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• v.27 no.4
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• pp.211-218
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• 2022

Recent vehicle regulations have become increasingly stringent in order to reduce greenhouse gases. Then not only movement to replace internal combustion engine vehicles with hybrid vehicles, but also studies of replacing internal combustion engine fuels with low-pollution fuels are increasing. In this study, the characteristics of a vehicle with LPG fuel engine and mild hybrid system is investigated. To avoid shortage of maximum power on LPG engine, a direct injection system of LPG is applied. In addition, P0 mild hybrid system is adopted to enhence the efficiency of the vehicle. The vehicle model is developed in order to predict fuel economy and CO2 emission of LPDi MHEV.