• Journal of Advanced Marine Engineering and Technology
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• v.34 no.5
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• pp.743-749
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• 2010

The primary object of this study was to develop the control algorithm and program for automatic submersible buoy which is free to move vertically within the water column by adjusting weight and buoyancy forces by air control. The experiment was performed to validate the usefulness of the program in the indoor water tank. In the experiment, the automatic submerging and surfacing of the buoy were controlled by water-pressure gauge and air control system. The buoy is raised by injecting compressed air from a compressor and then is lowered by releasing the air. The submerging and surfacing characteristics of the buoy calculated with the numerical model were similar to measurements obtained with the experiment. It was concluded that the algorithm and program could be useful in analyzing various parameters and submerging mechanisms required to design new type of automatic submersible fish cage system.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1955-1961
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• 2008

A lot of researches on a linear induction motor(LIM) have been advanced to realize a traction system with high efficiency and performance for railway transit for a long time. However, most of them are limited in design of a LIM part such as Primary and Secondary. At a LIM which is traveling, the change of an air-gap(It occurs by a construction tolerance of a secondary reaction plate) becomes the cause which decreases a smoother ride and the efficiency of railway transit system. Therefore, uniform air-gap operation of LIM is important issue to improve the system efficiency. However, the researches which control the air-gap length of the LIM with technical and high-cost problem have been not advanced a lot. Therefore, in this research, it is introduced an air-gap control system for performance test machine of a scale-downed LIM which is able to control the air-gap length of the LIM and monitor a variety of performance changes of the propulsion system, and conducted a research on feasibility of the system based on characteristic analysis.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.539-546
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• 2006

The Air Quality Sensor(AQS), located near the fresh air inlet, serves to reduce the amount of pollution entering the vehicle cabin through the HVAC(heating, ventilating, and air conditioning) system by sending a signal to close the fresh air inlet door/ventilation flap when the vehicle enters a high pollution area. The sensor module which includes two independent sensing elements for responding to diesel and gasoline exhaust gases, and temperature sensor and humidity sensor was designed for intelligent AQS in automobile. With this sensor module, AVR microcontroller was designed with back propagation neural network to a powerful gas/vapor pattern recognition when the motor vehicles pass a pollution area. Momentum back propagation algorithm was used in this study instead of normal backpropagation to reduce the teaming time of neural network. The signal from neural network was modified to control the inlet of automobile and display the result or alarm the situation in this study. One chip microcontroller, ATmega 128L(ATmega Ltd., USA) was used for the control and display. And our developed system can intelligently reduce the malfunction of AQS from the dampness of air or dense fog with the backpropagation neural network and the input sensor module with four sensing elements such as reducing gas sensing element, oxidizing gas sensing element, temperature sensing element and humidity sensing element.

• Journal of Korea Trade
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• v.27 no.3
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• pp.119-146
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• 2023

Purpose - As the severity of air pollution caused by the shipping industry is becoming evident, port authorities have started making efforts to reduce air pollutants. Considering the limitations of the currently implemented emission-control area (ECA) and vessel-speed reduction program (VSRP), which are narrow in the designation range and navigation behavior of ships, this study proposes an emission-control route (ECR) that can complement the aforementioned two environmental policies. Design/methodology - This study was conducted on Korea-China trade service routes (ports of call) of regular liners. This study employed vessel-specific data, which is from an automatic identification system (AIS), for 1,728 maritime transportations performed by 387 container vessels during one year (July 1, 2021, to June 30, 2022). Performing a scenario analysis, this study analyzed the effectiveness of reduced air-pollutant emissions. Findings - This study found that the implementation of ECRs could increase average voyage time by 12.38%-25.28% but reduced air-pollutant emissions by 29.02%-43.54%. Additionally, the increase in average voyage times reduces the anchorage time of ships outside ports, providing an incentive for ship operators to voluntarily participate in compliance with regulations, thereby contributing to the establishment of a virtuous cycle of air-environmental policies related to ships. Originality/value - This study aims to verify the policy effectiveness by designing an ECR scope for liner trade routes between Korea and China. Therefore, originality and the value of this study includes conceptualizing the ECR system, analyzing its environmental performance, and exploring new policies that can be implemented while complementing existing policies.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.328-333
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• 2007

The purpose of this study is modelling of system air-conditioner for TRNSYS. System air-conditioner is operated by a variable capacity compressor and accommodated by multiple evaporators. By reason of these feature, realizing performance of system air-conditioner for TRNSYS was incomplete. In this study performance data of system air-conditioner and control logics are used to make system air-conditioner module for TRNSYS. Performance data contains total capacity, power input and capacity index of system air-conditioner. The simulation was carried out in a mode of temperature level control using TRNSYS 16. The simulation shows that the system air-conditioner model operate variable capacity and can compute capacity index and power input of system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.4
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• pp.187-194
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• 2015

This paper describes the PI controller design based on a practical transfer function model for centrifugal water chillers. The rotational speed of a compressor and the opening angle of an electronic expansion valve were simultaneously regulated as manipulated variables to maintain temperature reference and to ensure high efficiency of the chiller. The COP according to the change in each variable was investigated by performing some static experiments, and it was reflected in the PI controller design to accomplish the high efficiency control. Especially, the practical transfer function model of the chiller was built based on the dynamic experimental data considering the strong inherent non-linearity and complexity of the chiller system. The validity of the designed PI controller was proven by some experimental results using the test facility and the results were also compared to the conventional evaporating pressure control results.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.49-58
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• 2006

In the respect of the environmental protection viewpoint, $CO_2$ may be one of the most attractive alternative refrigerants for an automotive air-conditioning system. For the development of control algorithm of a $CO_2$ automotive air-conditioning system, characteristics of a $CO_2$ refrigerant should be considered. The high-side pressure of a $CO_2$ system should be controlled in order to improve the system efficiency. In this study, dynamic physical models of a $CO_2$ system were developed and dynamic behaviors of the system were predicted by using these models. Control algorithms of a $CO_2$ system were also developed and the effectiveness of these algorithm was verified by using dynamic models.

• 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 Aerospace System Engineering
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• v.18 no.1
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• pp.29-36
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• 2024

Recently, the concept of Urban Air Mobility (UAM) has expanded to Advanced Air Mobility (AAM). A tilt rotor type of vertical take-off and landing aircraft has been actively studied and developed. A tilt-rotor aircraft can perform a transition flight between vertical and horizontal flights. A blade pitch angle control system can be used for flight stability during transition flight time. In addition, Individual Blade Control (IBC) can reduce noise and vibration generated in transition flight. This paper proposed Disturbance Observer Based Control (DOBC) and Time Delay Control (TDC) for individual blade control of an Electro-Mechanical Actuator (EMA) based blade pitch angle control system. To compare and analyze proposed controllers, numerical simulations were conducted with DOBC and TDC.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_1
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• pp.149-159
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• 2022

Biomass is material that is comprehensive of carbonaceous materials from plants, crops, animals, and algae. It has been used as one of heating fuel since the beginning the emergence of human beings. Since biomass is regarded as carbon-neutral energy source, it has recently been attracting attention as an energy source that can replace fossil fuels. The most widely applied field is distributed power generation, and a method of generating electric power by driving an internal combustion engine with syngas produced by gasifier is chosen. While the composition of the syngas produced in gasifiers changes depending on the air flowing into the reactor, commercialized gasifiers so far do not control the air flowing into the reactor. When the inner pressure in reactor increases, the air sucked into the reactor is reduced. That change of amount of air makes the composition of syngas varied. Those variations of composition of syngas cause the incomplete combustion hence the power output of engine drops, which is a critical weakness of the gasification technology. In this paper, to produce the uniformly composed syngas, PID control is applied. The result was shown when the amount of air into the reactor is supplied with the constant amount using PID control, the standard deviation of caloric values of syngas is around 2[%] of its average value. Meanwhile the gasifier without PID control has the standard deviation of caloric values is around 7[%]. Therefore, Adopting PID control to supply constant air to the gasifier is highly desirable.