• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.1
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• pp.1-8
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• 2012

Recently, the needs of system performances such as working speed and processing accuracy in machine tools have been increased. Especially, the speed increment generates harmful heat at both moving part of the machine tools and handicrafts. The heat is a main drawback to progress accuracy of the processing. Hence, a cooler system to control temperature is inevitable for the machine tools. In general, two representative control schemes, hot-gas bypass and variable speed control of a compressor, have been adopted in the water cooler system. In this paper, comparisons of system performances according to the control schemes in a cooler for machine tools were conducted in detail. Each proportional-integral feedback controller for the two different control systems is designed. The system performances, especially the temperature control accuracy and coefficient of performance which is a criterion of energy saving, were mainly analyzed through various experiments using 1RT water cooler system with different two types of control scheme. These evaluations will provide useful information to choose suitable water cooler system for the engineers who design controllers of the cooler system for machine tools.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.278-284
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• 2006

The popularity of the diesel engine revolves around its fuel efficiency, reliability, and durability compared to the gasoline engine. However, the main disadvantage of diesel engine is the emission of particulate matter (PM) which is known as carcinogenic substance. Therefore recent progress in engine management and after-treatment systems has led to great improvement to satisfy strict emission regulations. To comply with powerful environment regulations, this study is focused on the decrease of PM(soot) as to increase significantly exhaust temperature. Therefore, HC injection is used as the method to go to the PM regeneration temperature in front of filters composed of diesel oxidation catalyst(DOC) and diesel particulate filter(DPF). And especially, LPG is used because it has good chemical reactions with exhaust. In this study, we could manufacture the test bench thought LPG injection - with which soot can be decreased-, construct 3 kinds of database(DB) according to quantity of temperature to decide the LPG injection quantity and develop DPF ECU algorithm.

• The Journal of the Korea Contents Association
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• v.20 no.10
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• pp.1-13
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• 2020

There are many factors that influence the image quality of CMOS camera images, among which the image exposure time is an important factor. If the image exposure time is long, the entire image on the screen becomes brighter. If the exposure time is shorter, the entire image becomes darker. When photographing a still image, real time is not required because the automatic exposure system is given sufficient time to obtain an appropriate exposure time. However, if the surroundings and environment change rapidly like the black box of a driving car, the exposure time should be applied in response to real time. To this end, a robust automatic exposure system for real-time performance and ambient light environment is required. An automatic exposure system that has real-time capability and is robust against the ambient light environment is required. we designed a real-time control sysem capable of parallel operation processing through the design of an embedded system using zynq's logic and ARM core, and developed a real-time CMOS automatic exposure system that is robust to noise and converges to a desired target value within 66 ms through PID control.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.98-110
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• 2015

Recently, a validation research of maneuvering and attitude control logics of a spacecraft under a ground condition is getting increase by using operating simulators with compact and precise components. For that, a cold gas propulsion system is generally used for maneuvering and attitude control of spacecraft ground simulators for its simplicity and a high reliability. In the present study, major design parameters of a cold gas propulsion system are derived to meet mission requirements based on conceptual design results of a simulator. And additionally, commercial components with proper specifications are selected for system assembly.

• Journal of IKEEE
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• v.12 no.1
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• pp.59-64
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• 2008

In this paper, a new efficient SMPS has been designed and implemented. It can replace the existing product that is widely used in industry. To investigate the performance of the conventional SMPS, the output voltage changes due to variations in the input voltage and the load conditions, and the ripple and noise voltages have been measured and analyzed. As a result, it has been confirmed that the noise in the conventional SMPS is severe due to the deficiency of patterns for current. This is because the conventional SMPS draw out all outputs using one transformer and the alarm logic exists in the output path. To solve this problem, the switching frequency is increased from 17KHz to 70KHz and the current patterns are fully guaranteed by separating the alarm circuit and PWM circuit as a sub-board from the main board. Measurement results shows that the output noise of the designed SMPS decreases below 32% of the conventional SMPS noise for various test conditions, and both the line and load regulations are improved.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.659-665
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• 2010

This paper proposes a control algorithm for quadruped robots moving on irregularly sloped uneven surfaces. Since the body balance of a quadruped robot is controlled by the forces acting on its feet during touchdown, the ground reaction force (GRF) is controlled for stable running. The desired GRF for each foot is generated on the basis of the desired galloping pattern; this GRF is then compared with the actual contact force. The difference between the two forces is used to modify the foot trajectory. The desired force is realized by considering a combination of the rate change of the angular and linear momenta at flight. Then, the amplitude of the GRF to be applied at each foot in order to achieve the desired linear and angular momenta is determined by fuzzy logic. Dynamic simulations of galloping motion were performed using RecurDyn; these simulations show that the proposed control method can be used to achieve stable galloping for a quadruped robot on irregularly sloped uneven surfaces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1555-1560
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• 2013

The Column type Motor Driven Power Steering(CMDPS) systems are generally equipped among passenger vehicles ensuring better vehicle safety and fuel economy. In general to analyze systems and to develop a controller a full vehicle model from CarSim developed by Mechanical Simulation Incorporation interacting with MDPS control algorithm from Matlab Simulink was concurrently simulated. This paper describes the development of concurrent simulation technique in detail for analyzing Matlab Simulink MDPS control system with a dynamic vehicle system because the specific method has not been revealed in detail. The steering wheel angle input was evaluated and well compared with proving ground experimental data. The comparisons from concurrent simulation show an effective way to develop and validate the control algorithm. This concurrent simulation capability will be efficiently used for CMDPS performance evaluation and logic tuning as well as for vehicle handling performance.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.125-132
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• 2005

Visual programs consist of user interfaces and process logics. Because most visual IDEs(Integrated Development Environment) are utilized by only one developer, many developers can't cooperate simultaneously in one large-scaled visual Program to promote the development efficiency. This paper suggests a co-development environment for visual programs through which developers can cooperate with each other in the type of distribution. Developers can maintain the coincidence and the confidence of cooperation through a communication window and a job controller to process the Priority of the events that developers make in co-development work. Especially in large-sealed visual Program, the suggested environment reduces the burden that developer takes about the heavy development work, and many developers can divide and take the complex and large program modules according to their ability. We hope that the suggested environment can improve the development productivity and effectivity because it can reduce the time and effort for developing user interfaces in visual programs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1317-1327
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• 2016

The baggage handling system (BHS) is one of the most complex system in the airport. A highly economical operating system is required to ensure its performance in consideration of its enormous cost on the extension. Furthermore, the inefficient operation deteriorates not only the system performance but the imbalance among the check-in counters because of a bottleneck on the conveyors downstream. The objective of this research is to improve the performance of both the BHS and the check-in area by efficiently controlling the flow in the merging area on the conveyors. Thus, we suggest a control logic of which the concept is borrowed from data networks. The simulation is used to analyze impacts of the conveyors bottleneck on the check-in area and optimize some parameters used in the suggested logic. We also discuss some observations from the simulation results into several aspects of performance measures.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.742-751
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• 2018

In this paper, we propose a time varying biased proportional navigation guidance law that controls the impact angle under Field-of-View(FOV) and the acceleration limit of the missile. The proposed law is composed of three stages in consideration of the FOV limitation. Since the bias directly affects the acceleration at each stage, the final bias value of the previous stage becomes the initial bias value of the next stage when the stage is switched. In addition, the impact angles were controlled by judging whether impact angles were reached in consideration of engagement conditions and physical constraints.