• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.234-242
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• 2002

In this research, a transmission control unit was developed for a wheel loader on the basis of 16-bit microcontroller system. The TCU has the basic functions which include shifting control algorithm, actuation of six proportional solenoid valves, signal conditioning for four speed sensors, remote data monitoring capability with RF-module and duty cycle identification system which could identify the duty cycles from PWM signals. In order to design the control system, the overall transmission structure of the wheel loader was investigated and its characteristics of shifting were analyzed in advance. For the purpose of identifying the existing control algorithm and acquire some information about the shifting performance, the shifting experiments were performed for various shifting conditions with the conventional TCU. From the previous work on the conventional TCU, the shifting scheme was designed with the open-loop control which is based on the experimental data only to verify the feasibility of the developing TCU's shilling capability. The experimental results show comparable shifting characteristics to that of conventional TCU though the tests were performed at restricted shilling conditions. Hence, we could have the confidence for the development of the wheel loader automatic transmission TCU and its shifting quality could be improved with the adoption of appropriate feedback control scheme.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1225-1228
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• 2011

This paper presents an advanced energy saving algorithm in building. It is important to aggregate a various demand side resource which is controllable on demand response environment. Previous demand side algorithm for building is restricted on peak power. In this paper, we suggest duty cycle algorithm for AHU on demand response to reduce the quantity of building power consumption. The test results show that the proposed algorithm is very effective.

• Journal of Communications and Networks
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• v.14 no.1
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• pp.40-50
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• 2012

The Berkeley-medium access control (B-MAC) is a lightweight, configurable and asynchronous duty cycle medium access control (MAC) protocol in wireless sensor networks. This article presents an analytic modelling of single-hop B-MAC protocol under a Poisson traffic assumption.Our model considers important B-MAC parameters such as the sleep cycle, the two stage backoff mechanism, and the extended preamble. The service delay of an arriving packet and the energy consumption are calculated by an iterative method. The simulation results verify that the proposed analytic model can accurately estimate the performance of single-hop B-MAC with different operating environments.

• Korean Journal of Agricultural Science
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• v.37 no.1
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• pp.123-130
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• 2010

A steering control system based on CAN(Controller Area Network) for autonomous tractor was developed to reduce duty of a central processing computer and to improve performance of steering control in terms of reduced control interval and error. The steering control system consisted of a SCU (Steering Control Unit), an EHPS system, and a potentiometer. The SCU consisted of an MCU (Micro Controller unit), an A/D converter, and a DC-DC converter, and a PID controller was used to control steering angle. The steering control system was communicated with the computer by CAN-bus. Each actuator and implement was connected to a multi-function board interfacing with the computer through a USB cable. Without CAN, control interval of the autonomous tractor was 1.5 seconds. When the CAN-based steering control system was combined with the autonomous tractor, however, control interval of the integrated system was reduced to those less than 0.05 seconds. When the autonomous tractor was operated with 1.5-s and 0.05-s control cycles at a 0.63-m/s travelling speed, the trajectories were close to straight lines for both of the control cycles. For a 1.34-m/s traveling speed, tractor trajectory was close to sine wave with a 1.5-s control cycle, but was straight line with a 0.05-s control cycle.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.161-169
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• 2009

The development of Wireless Multimedia Sensor Networks(WMSNs) is getting realized in accordance with the increased demands to provide multimedia data transmission service such as CCTV movie, image chapter information, audio information based on wireless sensor network. It is very important to provide the differentiated quality assurance of service. In this paper, we propose a sensor medium access control protocol based on DSMAC, which provides differentiated Quality of Service(QoS) for delay. A proposed protocol is able to reduce the delay without increasing the energy consumption by adaptively changing the duty cycle according to the buffer occupancy. Simulation results show that the new MAC protocol performs better in terms of latency than S-MAC and DSMAC.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.4
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• pp.491-497
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• 2015

In this paper a method of design and Implementation of RFID based control system for reducing standby power consumption at the power outlet is described. The system is composed of a RF controlled power outlet having relay and an active RFID tag communicating with the RF reader module controlling the relay. When the tag carried by human approaches to the RF reader the reader recognizes the tag and switch off the relay based on the RSSI level measurement. A low power packet prediction algorithm has been used to decrease the DC power consumption at both the tag and the RF reader. The result of experiment shows that successful operation of the relay control has been obtained while low power operation of the tag and the reader is achieved using above algorithm. Also setting the distance between the reader and the tag by controlling transmission power of the tag and adjusting the duty cycle of the packet waiting time when the reader is in idle state allows us to reduce DC power consumption at both the reader and the tag.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.2
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• pp.61-68
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• 2014

Function of battery bank stores energy for DC load in general, and DC power system of the nuclear power plant is used to supply DC loads for safety- featured instrumentation and control such as inverter, class 1E power system control and indication, and station annunciation. Class 1E DC power system must provide a power for the design basis accident conditions, and adequate capacity must be available during loss of AC power and subsequent safe shutdown of the plant. In present, batteries of Class 1E DC power system of the nuclear power plant uses lead-acid batteries. Class 1E batteries of nuclear power plants in Korea are summarized in terms of specification, such as capacity, discharge rate, bank configuration and discharge end voltage, etc. This paper summarizes standards of determining battery size for the nuclear power plant, and analyzes duty cycle for the class 1E DC power system of nuclear power plant. Then, battery cell size is calculated as 2613Ah according to the standard. In addition, this paper analyzes performance test results during past 13 years and shows performance degradation in the battery bank. Performance tests in 2001 and 2005 represent that entire battery cells do not reach the discharge-end voltage. Howeyer, the discharge-end voltage is reached in 14.7% of channel A (17 EA), 13.8% of channel B (16 EA), 5.2% of channel C (6 EA) and 16.4% of channel D (19 EA) at 2011 performance test. Based on the performance test results analysis and size calculation, battery capacity and degradation by age in Korearn nuclear power plant is discussed and would be used for new design.

• Journal of Power System Engineering
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• v.5 no.2
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• pp.13-21
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• 2001

Diesel emission control is being addressed worldwide to help preserve the global environment. This paper mainly deals with the effects of oxidation catalysts to reduce emissions from the automotive heavy-duty diesel engine. Two types of the oxidation catalyst with different kinds of precious material were used. An 11 litter displacement diesel engine with turbocharger was operated to evaluate DOC with various engine speed, load conditions under D-13 mode cycle. We could propose the detail emission data of an automotive heavy-duty diesel engine and the characteristics of the conversion efficiency of the DOC under the D-13 mode. It was found that the mean conversion efficiencies of CO and THC were 49.7% and 61% under the D-13 mode test, respectively.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.435-436
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• 2016

본 논문에서는 3상 Quasi Z-소스 AC/AC 전력변환기를 제안한다. 제안된 전력변환기는 3대의 단상 Quasi Z-소스 AC/AC 컨버터로 구성되어 있으며, 간단한 듀티 비 제어만으로도 동상 및 역상의 벅-부스트 출력 전압의 발생이 가능하다. 제안된 방식은 PSIM 시뮬레이션을 통하여 타당성을 확인하였다.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.85-88
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• 1996

New power factor correction(PFC) technique based on the averaged model of boost converter is proposed. Without measurement of input current, power factor correction scheme derived from the averaged model is presented. With the measurements of input voltage and output voltage, the control signal is generated to make the shape of the line current same as the input voltage. The characteristics of input line current distortion is analyzed by considering the generation of duty cycle.