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RISS 인기검색어
- 검색키워드
- 저자 : Young Kow Lee (검색결과 5 건)
- 무료
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- 유료
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Adaptive Feed-forward Automatic Gauge Control in Hot Strip Finishing Mill
Lee, Young Kow,Jang, Yu Jin,Kim, Sang Woo Iron and Steel Institute of Japan 2007 ISIJ international Vol.47 No.10
<P>The conventional roll force automatic gauge control (RFAGC) adjusts the roll gap to reduce the delivery thickness variation in the hot strip finishing mills. In this process, the information about the roll force is used to control the roll gap indirectly because the strip gauge cannot be measured owing to insufficient space in the mill and the hostile environment. Moreover, there exists an uncertainty in thickness due to roll eccentricity. Therefore, a small gain is preferable in avoiding product defects when this uncertainty is taken into account in RFAGC. However, in such a case, partially uncontrolled variation still remains on delivery thickness because of insufficient control input. To overcome this drawback, a feed-forward controller (FFAGC) was developed.<SUP>12)</SUP> This scheme adjusts the roll gap to reduce variations in the current stand by using an estimated uncontrolled delivery thickness variation of the previous stand. Although this FFAGC has an advantage over RFAGC, it still has a problem: The FFAGC cannot cope with the continuous variation of system parameters and circumstance because the existing feed-forward controller has been designed as a low pass filter with constant weights. In other words, desirable control performance in the automatic gauge control system cannot be obtained owing to a phase delay and filtering errors.To overcome the problem, it is essential to estimate the long-term thickness variation exactly in the hard environment, to select a proper gain and to synchronize the feed-forward control input under a time varying speed of the gauge control process. In this paper, an enhanced adaptive filtering structure is proposed to improve the controller performance. And the relation between the gains of RFAGC and FFAGC are discussed to select a proper gain. The proposed controller can readily be implemented on the conventional control system, improving the performance of the system without additional cost. This improvement was demonstrated by using the real coil data which are collected under the proposed control scheme in POSCO.</P>
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Online Gain Tuning Method of Roll Force AGC in Hot Strip Mills by Using Fuzzy Logic
Kow LEE, Young,Jin JANG, Yu,Woo KIM, Sang Institute of Electronics, Information and Communic 2007 IEICE transactions on fundamentals of electronics, Vol.90 No.6
<P>Gains of a roll force AGC (Automatic Gain Controller) have been calculated at the first locked-on-time by FSU (Finishing-mill Set-Up model) in hot strip mills and usually these values are not adjusted during the operating time. Consequently, this conventional scheme cannot cope with the continuous variation of system parameters and circumstance, though the gains can be changed manually with the aid of experts to prevent a serious situation such as inferior mass production. Hence, partially uncontrolled variation still remains on delivery thickness. This paper discusses an effective online algorithm which can adjust the gains of the existing control system by considering the effect of time varying variables. This algorithm improves the performance of the system without additional cost and guarantees the stability of the conventional system. Specifically, this paper reveals the major factors that cause the variation of strip and explores the relationship between AGC gains and the effects of those factors through the analysis of thickness signal which occupy different frequency bands. The proposed tuning algorithm is based on the above relationship and realized through ANFIS (Adaptive-Neuro-based Fuzzy Interface System) which is a very useful method because its fuzzy logics reflect the experiences of professionals about the uncertainty and the nonlinearity of the system. The effectiveness of the algorithm is shown by several simulations which are carried out by using the field data of POSCO corporation (South Korea).</P>
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김영화(Young Hwa Kim),김형권(Hyung kow Kim),이태석(Tae suk Lee),오성식(Sung sik Oh),유영선(Young sun Ryou) (사)한국생물환경조절학회 2020 생물환경조절학회지 Vol.29 No.1
본 연구는 일정한 풍환경하에 온실 피복재 관류전열손실을 분석하기 위하여 온실 열손실 분석용 소형 풍동을 제작하고 그 성능을 분석하였으며 모형온실을 적용하였을 때의 관류전열손실을 분석하였다. 소형 풍동은 시험부 측 공기흐름이 정상상태를 유지하고 편차를 최소화하기 위하여 풍동의 각 요소를 반영하여 구성하였으며 송풍부, 확산부, 정류부, 축소부, 시험부로 구성하였다. 소형 풍동의 형태는 개방형, 토출식으로 결정하였고, 시험부 규격은 제작하고자 하는 모형온실의 규격과 상사비율, 시험부의 단면 폐쇄율을 감안하여 결정하였다. 상사비율을 풍동실험에 적용할 모형은 농업시설 중 가장 큰 비중을 차지하고 있는 단동 비닐온실을 대상으로 하였다. 소형풍동 내 풍속을 조절함에 따라 나타나는 모형온실 피복재의 관류전열계수는 피복재 면을 크게 지붕면과 측벽면, 앞뒷면으로 나누고 각 면별 계측 데이터를 평균 내어 산출하였다. 지붕면은 풍속이 증가함에 따라 전열계수도 증가하나 증가폭이 감소하는 구간은 배치각도에 따라 1-2ms<SUP>-1</SUP>과 2-3ms<SUP>-1</SUP>으로 구분되어지는 것으로 판단되었다. 측벽면의 전열계수가 증가하는 폭이 큰 구간은 0-1ms<SUP>-1</SUP> 구간인 것으로 판단된다. The objective of this study is to analyze the heat transfer loss of covering materials in a single-span plastic greenhouse under the steady-state wind environment. To achieve this objective, the following were conducted: (1) design of a small-scaled wind tunnel (SCWT) to analyze heat losses of the greenhouse and its performance; (2) determination of the overall heat transfer coefficient (OHTC) for the covering materials using a small-scaled greenhouse model. The SCWT consists of the blowing, dispersion, steady flow, reduction and testing areas. Each part of the SCWT was customized and designed to maintain air flow at steady state and to minimize the variances in the SCWT test. In this study, the OHTCs of the covering materials were calculated by separating each with the roof, side wall, front and back of the small-scaled greenhouse model. The results of this study show that the OHTC of the roof increases as wind speed increases but the zones in which the increase rate of the OHTC decreased, were distinguished by wind tunnel wing speed of 2 ms<SUP>-1</SUP>. For the side wall, the increase rate of the OHTC was particularly higher in the 0-1 ms<SUP>-1</SUP> zone.
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