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무선 인터넷 프록시 서버 클러스터 환경에서 호스트 부하 정보에 기반한 동적 스케줄링
박홍주(Hongjoo Park),곽후근(Hukeun Kwak),정규식(Kyusik Chung) 한국정보과학회 2005 한국정보과학회 학술발표논문집 Vol.32 No.1
무선 인터넷 프록시 서버 클러스터에서 부하 분산기는 사용자의 요청을 각 서버(호스트)로 분산시키는 역할을 한다. 리눅스 가상서버(LVS: Linux Virtual Server)는 소프트웨어적으로 사용되는 부하 분산기로서 여러 가지 스케줄링 방식들을 가지고 있다. 그러나 부하 분산시에 서버(호스트)의 유동적인 부하 정보를 반영하지 못하는 단점이 있다. 이에 개선된 방식으로 서버의 동시 연결 개수에 따라 상한계(Upper Bound)와 하한계(Lower Bound)를 설정하고, 요청을 분산하는 동적 스케줄링(Dynamic Scheduling)이 존재한다. 그러나 사용자의 요청 컨텐츠에 따라 상한계와 하한계가 바뀔 수 있음에도 불구하고 이 값들이 고정되어 있다는 단점을 가진다. 본 논문에서는 호스트 부하 정보에 기반한 스케줄링 방식을 제안한다. 제안된 방식은 호스트의 부하 정보를 바탕으로 사용자의 요청을 분산하였으며, 사용자의 요청에 따라 상한계와 하한계가 바뀔 수 있음을 고려하여 상한계와 하한계를 설정하지 않고 사용자 요청 컨텐츠에 따라 적절하게 요청이 분배되도록 하였다. 16대의 컴퓨터를 사용하여 실험을 수행하였으며, 실험 결과 사용자가 요청하는 컨텐츠가 동일한 경우에는 기존 스케줄링 방식과 13% 성능 감소를, 다른 경우에는 기존 스케줄링 방식보다 102%의 성능 향상을 보임을 확인하였다.
표면부착형 영구자석 동기전동기의 자속기반 고성능 토크 제어
박홍주(Hongjoo Park),김종인(Jongin Kim),이헌형(Heonhyeong Lee),송재석(Jaeserk Song),강병배(Byeongbae Kang),이근호(Geunho Lee) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
Recently study of eco-friendly cars has been carried out actively. Meanwhile, the established mechanism have been replaced by Eco-friendly and efficiency electric motor. Thereof, low saliency surface mounted permanent synchronous motor is selected for Electric Power Steering System(EPS) to acquire the higher steering feeling. Such these driver system are battery-powered that will lead to the DC-link voltage varied according to load current variation and regenerated status. In general, the Torque-Speed mapping is employed without taking into account the DC-link voltage variation in torque control system. Consequently, the additional mapping is indispensable for the high performance estimation of DC-link voltage variation and that is make the system more complicant and responsiveness more slowly. A new torque control system is proposed aim at these drawback with a Flux-Torque mapping to address the issues due to the variations of voltage and speed in practical application in this paper. The proposal current map performance is verified that is capable of dealing the DC-link voltage variation in the MATLAB/SIMULINK and a 500W SPMSM is used to test the feasibility of proposed strategy by a 1kW inverter equipped with Microprocessor Aurix Tricore TC 264D (Infienon.co.)
무인비행기 직렬 하이브리드 추진 시스템에서의 효율적인 배터리 공급을 위한 알고리즘 개발
박규성(Kyusung Park),이한상(Hansang Lee),박홍주(Hongjoo Park),진원준(Wonjoon Jin),이근호(Geunho Lee) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.3
Recently, the number of use of unmanned airplanes has been increased, and studies have been conducting to increase the cruising time. In the case of an unmanned airplane with a small capacity, the motor is used to drive the propeller instead of using the engine. And it uses the battery to drive the propeller motor. Instead of reducing the weight of the battery, it can be increased the cruising time by adding engines, generators and converters and performing power generation control. In this paper, we installed a current sensor between the BLDC motor drive and the battery. the algorithm that perform efficient power generation control according to the power required by the propeller is developed. And it can adjust the amount of regenerating electric power. We proposed a power generation algorithm that regenerates in response to load fluctuations, and verified it through simulations and experiments.
김도군(Dokun Kim),박홍주(Hongjoo Park),박규성(Kyusung Park),김선형(Seonhyeong Kim),이근호(Geunho Lee) 제어로봇시스템학회 2015 제어·로봇·시스템학회 논문지 Vol.21 No.2
In hybrid or electric vehicles, the hydraulic brake system must be controlled cooperatively with the traction motor for regenerative braking. Recently, a motor driven brake system with a PMSM (Permanent Magnet Synchronous Motor) has replaced conventional vacuum boosters to increase regenerative power. Unlike industry motor controls, additional source codes such as functional safety are essential in automotive applications to meet ISO26262 standards. Therefore, the control logic execution time increases, which also causes an extension of the motor current control period. The increased current control period makes precise motor current control challenging inhigh speed ranges where the motor is driven by high frequency. In this paper,a PWM update strategy and a time delay compensation method are suggested to improve current control and system performance. The proposed methods are experimentally verified.
EPS용 저전압 대전류 유도 전동기의 고효율 간접 벡터제어
고형곤(Hyeonggon Ko),박홍주(Hongjoo Park),박규성(Kyusung Park),이근호(Geunho Lee) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
The studies about an induction motor was not active. However, in recent years, as increasing the price of permanent magnet(Rare earth resources magnet), the studies of the induction motor are becoming more active than before. And advantages of the induction motor are low-priced, easy to make and strong at high speed. But the problems are poor torque response and low efficiency. When the induction motor is driven under light load with rated exciting current, the iron loss is much larger than the copper loss. This study is deal with strategy of high efficiency indirect vector control in EPS. This algorism improves the problems which are torque response and low efficiency.