• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.191-198
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• 2014

A semi-pilot hybrid system composed of a photocatalytic reactor and a biofilter was operated under various operating conditions in order to treat malodorous waste air containing both hydrogen sulfide and ammonia which are major air pollutants emitted from composting factories and many publicly owned treatment works (POTW). When both hydrogen sulfide and ammonia contained in malodorous waste air were treated simultaneously by a biofilter system, its performance of ammonia removal was much more poor than that by a biofilter system treating waste air containing only ammonia, unlike its performance of hydrogen sulfide removal. For semi-pilot hybrid system, the removal efficiencies of hydrogen sulfide and ammonia turned out to be ca. 83 and 65%, respectively. Therefore, for semi-pilot hybrid system, the removal efficiencies of hydrogen sulfide and ammonia was increased by ca. 4 and 30%, respectively, compared to those of semi-pilot biofilter system (control). In addition, the maximum elimination capacities of hydrogen sulfide and ammonia for semi-pilot hybrid system turned out to be ca. 60 and $37g/m^3/h$, respectively. These maximum elimination capacities of hydrogen sulfide and ammonia were estimated to be ca. 9.1% and ca. 23.3% greater than those for semi-pilot biofilter system (control), respectively. Therefore, the semi-pilot hybrid system contributed the enhancement of removal efficiency and the maximum elimination capacity of ammonia in a higher degree than that of hydrogen sulfide, compared to the semi-pilot biofilter system.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.7
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• pp.704-713
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• 2011

For many years, many pilots lost their lives and aircrafts due to GLOC(Gravity-induced Loss Of Consciousness). Due to the emergence of high-gravity maneuvering aircraft such as the F-16, F-15 and T-50, the automatic GLOC detection and recovery systems are necessary to increase the aircraft safeties even when the pilot loses his consciousness due to high-G maneuvering. This paper addresses the design of GLOC detection, warning and recovery algorithm based on a model of supersonic jet trainer. The system is solely controlled by the pilot's control input (i.e., control stick force) and aircraft status such as attitude, airspeed, altitude and so forth. And, moreover, it does not depend upon any pilot physiological condition. The test evaluation results show that the developed system supports the recovery of an aircraft from the unusual aircraft attitude and improves the aircraft safeties even when the pilot loses his consciousness due to high-G maneuvering.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.102-108
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• 2010

In this study, the authors investigate the basic characteristics of a two stage directional control valve with pilot spool assembled in main spool coaxially. The step response characteristics and effects of major design parameters' values on valve performances arc clarified through numerical simulations. In addition, the authors examined the possibility of applying the object valve for this study as a proportional control valve. Based on the numerical simulation results, new design values for the reformed design as a proportional control valve were suggested.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.949-957
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• 2005

In this paper, the performances of a single-user DS-UWB system applying two simple proposed channel estimation schemes are introduced, according to the newly updated DS-UWB PHY Layer standard from IEEE P802.15.3a. The performances of error control coding, different combining schemes in selective Rake receiver for DS-UWB system are analyzed. Both of the two channel estimation schemes using data-independent structure work well in DS-UWB system with few pilot bits. For the purpose of channel estimation and reduces the number of pilot bits, we apply a pilot symbol spreaded with $2{^8}-1\;or\;2{^9}-1$ periods of m-sequence for different channel estimation schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.3
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• pp.571-579
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• 1997

There are some transmission types on the reverse link of wideband DS-CDMA cellular system. The configurations of logical channels on the reverse link may be different dependent upon the transmission methods of reverse pilot or control signaling. In this paper, we present three transmission types on the wideband DS-CDMA reverse link; no-pilot system, pilot-channel aided system and pilot-symbol aided system. And we compare the performance of three systems in terms of capacity and cell coverage. The pilot-symbol aided system is shown to have the better performance than the pilot-channel aided system in both capacity and cell coverage.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.367-371
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• 2004

This paper describes development of automatic flight control system for an unmanned target drone which is operated by Korean army as for anti-air gun shooting training. Current target drone is operated by pilot control of on-board servo motor via remote control system. Automatic flight control system for the target drone greatly reduces work load of ground pilot and can increase application area of the drone. Most UAVs being operated now days use high-priced sensors as AHRS and IMU to measure the attitude, but those are costly. This paper introduces the development of low-cost automatic flight control system with low-cost sensors. The integrated automatic flight control system has been developed by integrating combining power module, switching module, monitoring module and RC receiver as an one module. The performance of automatic flight control system is verified by flight test.

• Journal of Drive and Control
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• v.15 no.4
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• pp.11-16
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• 2018

Pilot operated control valve for $CO_2$ refrigerant is a valve that can perform various functions according to the user's intention by replacing pilot units, widely used for flow rate, pressure, and temperature control of refrigeration and air conditioning systems. In addition, $CO_2$ refrigerant, that requires high pressure and low critical temperature, can be installed and used in all positions of the refrigeration system, regardless of high or low pressure. In this paper, response characteristics are modeled and analyzed based on behavior of the main piston of the pilot-operated control valve. Although various factors influence operation of the main piston, this paper analyzes the effect of equilibrium pressure depending on valve installation position and application, and inlet and outlet orifice size of the load pressure feedback chamber to determine feedback characteristics of the main piston. As a result, it was possible to quantitatively analyze the effect of change in equilibrium and load pressure feedback chamber flow path size on the change in main piston dynamic and static characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.76-82
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• 2007

This paper described the effect of the multiple injections on the stability of combustion and emission characteristics in a direct injection diesel engine at various operating conditions. In order to investigate the influence of multiple injections in a diesel engine, the fuel injection timing was varied one main injection and two pilot injections at various conditions. The experimental apparatus consisted of DI diesel engine with four cylinders, EC dynamometer, multi-stage injection control system, and exhaust emissions analyzer. The combustion and emission characteristics were analyzed for the main, pilot-main injection, pilot-pilot-main injection strategies. It is revealed that the combustion pressure was smoothly near the top dead center and the coefficient of variations is reduced due to the effect of pilot injection. Also, $NO_x$ emissions are dramatically decreased with pilot injection because the decrease of rate of heat release. However, the soot is increased at early pilot injection and main injection.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.3
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• pp.40-47
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• 2018

Reducing aircraft speed is the important task in the Rejected Takeoff and/or landing process. It is known that the effect of the Speedbrake is most important factor during the rejected takeoff maneuver in particular near V1 on the critical field length runway. The B747 designer created Automatic Speedbrake Control System to relieve pilot workload, improves brake operation and ensures proper Speedbrake operation for rejected take off. However, those who make the Rejected Takeoff procedure ignored the Automatic function and made it does all manual operations. This lets procedures difficult, complicated, and a cause of confusion and pilot error. This study was conducted to commentary the mechanism and function of the Automatic Speedbrake Control System of B747-8 and to propose appropriate B747-8 Rejected Take off procedures for its function to reduce the workload of pilots and contribute to reduce the possibility of pilot error during Rejected Takeoff.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.2
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• pp.1-11
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• 2020

This study was carried out to verify how much instructor's communication skill affects the student pilot's study motivation and satisfaction. The instructor's communication styles are classified into 3 groups by pre-analysis. Three types are cooperative type, control type and professional type. Intellectual cause, performance proficiency cause, social cause and stimulation avoidance cause are extracted and analyzed for the cause of study motivation. Cooperative and control type affected all of 4 factors of student's study motivation by influence analysis. Intellectual cause affected control and cooperative type positively, especially more to cooperative type. Performance proficiency cause also had positive influence to control and cooperative type. Stimulation avoidance cause didn't appear to affect all sub-classified 4 factors of instructor's communication type. Influence analysis of student's study satisfaction from instructor's communication style showed that independent variable affected all sub factors positively. Degree of positive influence affected the control type the most, cooperative type was the 2nd, and professional type was the 3rd.