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주기적 확률외란을 갖는 DC 전동기의 적응형 상태궤한 제어시스템
鄭相鐵(Sang-Chul Jeong),金俊洙(Jun-Su Kim),曺賢哲(Hyun-Cheol Cho),李炯基(Hyung-Ki Lee) 대한전기학회 2008 전기학회논문지 Vol.57 No.6
Periodic disturbance is practically occurred in several engineering applications, especially in data storage systems. However, recently addressed controls for such problem were mostly dealt with its deterministic nature, which is rarely practical in real-time implementation. We present an adaptive control approach for DC motor systems with periodic stochastic disturbance whose frequency and magnitude are both random variables. We establish adaptive state feedback control which is linearly composed of nominal and corrective control parameter matrices. The former is derived from a nominal system model voiding disturbance and the latter is constructed from a disturbed system model by using Lyapunov stability theory. We carry out computer simulation to evaluate the proposed control methodology and compare to the recently addressed control method to demonstrate its superiority.
불확실성 요소를 갖는 3D 크레인 시스템의 강인적응제어
鄭相鐵(Sang Chul Jeong),金東源(Dong Won Kim),曺賢哲(Hyun Cheol Cho),李炯基(Hyung Ki Lee) 대한전기학회 2008 전기학회논문지 Vol.57 No.1
This paper presents robust and adaptive control method for complicated three dimensional crane systems with uncertain effect. We consider an overhead crane system in which a trolly located on its top is moved to x- and y-axis independently. We first approximate the complicated crane model through linearization approach to simply construct a PD control and then design an adaptive control system for compensating modeling error and control deviation which is feasibly occurred due to system perturbation in practice. An adaptive control scheme is analytically derived using Lyapunov stability theory for a given bound of system perturbation. We accomplish numerical simulation for evaluation of the proposed control system and demonstrate its superiority comparing with the traditional control strategy.
염화철(Ⅲ)처리 활성탄을 이용한 수중의 질산성질소 제거
유찬서 ( Chan-seo You ),정승광 ( Seung-gwang Jeong ),정정조 ( Cheong-jo Cheong ),정상철 ( Sang-chul Jung ),이경동 ( Gyeog-dong Lee ),라덕관 ( Deog-gwan Ra ) 한국환경기술학회 2009 한국환경기술학회지 Vol.10 No.3
염화철(Ⅲ)처리 입상 활성탄을 제조하여 수중에 존재하는 질산성질소의 제거 방안에 대하여 검토하였다. 염화철처리 활성탄은 일반 활성탄에 비하여 표면에 피흡착질을 축적할 수 있는 수많은 세공들이 관찰되었다. 질산성질소 제거율은 염화철처리 활성탄 첨가량 20g/L에서 96.2%로 가장 높았고, pH변화에 따른 질산성질소 제거율은 큰 차이가 질산성질소 나타나지 않았다. 온도가 증가할수록 질산성질소의 제거율은 감소하는 경향을 나타냄으로써 반응이 발열반응임을 확인할 수 있었다. 제거를 위한 적정 온도는 10℃이었으며, 그때 제거율은 96.2%를 나타냈다. 흡착등온식은 Freundlich식이나 Langmuir식으로 표현이 가능하였다. In order to remove the resolved nitrate in natural water, this study was carried out to investigate the nitrate removal efficiency by using an Iron chloride(Ⅲ) treated activated carbon. The treated activated carbon could be observed a lot of porosity better than conventional activated carbon that showed an elevated capacity of pollutant accumulation on its surface. The highest nitrate removal efficiency was recorded to 96.2 % by adopting of 20 g/L the treated activated carbon. Though the removal efficiency was not affected by pH variation, it showed a tendency in inverse proportion to water temperature. So this process was known to be an exothermic reaction, and optimum temperature in order to get 96.2 % nitrate removal efficiency was concluded to be 10℃. Additionally, the nitrate adsorption reaction between nitrate and Iron chloride(Ⅲ) treated activated carbon was well able to followed to Langmuir and Freundlich adsorption isotherm.
정상철,조현철,이형기,Jeong, Sang-Chul,Cho, Hyun-Cheol,Lee, Hyung-Ki 한국융합신호처리학회 2008 융합신호처리학회 논문지 (JISPS) Vol.9 No.1
전동기의 카오스 현상은 실시간 구현에 있어 바람직하지 않은 동특성으로서, 일반적으로 정상상태에서 전동기 속도가 진동을 한다든지 토크가 랜덤하게 변하는 특징이 있다. 본 논문은 카오스 현상을 갖는 영구자석형 동기 전동기의 적응제어기법을 제안한다. 전동기의 계수(parameter)는 어느 범위 안에서 랜덤하게 변화하는 시변특성을 갖는다. 제어기 설계는 우선, 전동기의 비선형 시스템 모델을 공칭 선형시스템 이론을 적용하여 선형화한다. 또한 실시간에서 시스템 계수의 변화로 인해 발생하는 제어오차를 보상하기 위한 보조제어기법을 제안하며 리아푸노브 안정성 이론을 적용하여 그 제어규칙을 산출한다. 컴퓨터 시뮬레이션을 통하여 제안한 제어기법의 타당성 및 신뢰성을 검증하며 기존의 제어기법과 비교 분석하여 성능의 우수성을 입증하였다. 또한 PSoC(Programmable System-on-Chip)기반 구동 드라이브를 포함하는 실시간 전동기의 제어시스템 실험을 통해 실제 적용가능성을 검증한다. Chaotic behavior in motor systems is undesired dynamics in real-time implementation since the speed is oscillated in a wide range and the torque is changed by a random manner. We present an adaptive control approach for time-varying permanent-magnet synchronous motors (PMSM) with chaotic phenomenon. We consider that its parameters are changed randomly within certain bounds. First, a nonlinear system model of a PMSM is transformed to derive a nominal linear control strategy. Then, an auxiliary control for compensating real-time control error occurred by system perturbation due to parameter change is designed by using Lyapunov stability theory. Numerical simulation is accomplished for evaluating its efficiency and reliability comparing with the traditional control method. Additionally, we test our control method in real-time motor experiment including a PSoC based drive system to demonstrate its practical applicability.
TiO<sub>2</sub> 광촉매 볼을 이용한 OrangeⅡ의 광촉매 분해
채정석 ( Jeong-seok Chae ),정상철 ( Sang-chul Jung ) 한국환경기술학회 2008 한국환경기술학회지 Vol.9 No.2
화학기상증착법으로 TiO<sub>2</sub> 광촉매 볼을 제조하였고, 광반응기를 이용하여 Orange II 수용액의 분해 실험을 통하여 광촉매활성을 평가하였다. 알루미나 볼 위에 TiO<sub>2</sub> 막을 코팅시켜 광촉매 볼을 제조 하였고, XRD, FT-IR, EDX, SEM 분석을 통하여 TiO<sub>2</sub> 광촉매 막의 특성을 검토하였다. Orange II의 광촉매 분해 실험에서 순환유속이 증가 할수록 분해속도가 증가하였고, 자외선램프의 파장이 클수록 그리고 pH의 값이 클수록 분해속도가 감소하는 경향을 나타내었다. 주입시킨 가스에 의한 Orange II의 분해속도는 산소 > 공기 > 무 첨가 > 질소 순으로 증가하였다. TiO2 photocatalyst ball was prepared by Chemical Vapor Deposition method, and photocatalytic activities were evaluated by decomposition rate of Orange II in aqueous solution using a photo-reactor. Photocatalysts balls were prepared by depositing TiO2 film on alumina balls, and the TiO2 films were characterized by a XRD, FT-IR, EDX, SEM. From the result of photocatalytic degradation of Orange II, decomposition rate were shown gradually increased according to the increase of circulating fluid velocity. However the decomposition rate of Orange II were decreased according to the increase of UV light wave length and pH value. The decomposition rate of Orange II by change of injection gases were indicated as O <sub>2</sub> > Air > No addtion > N <sub>2</sub>.
GHP 난방 모드 운전시 실시간 부하 추정방법에 관한 연구
서정아(Jeong A Seo),신영기(Younggy Shin),오세제(Se-Je Oh),정상덕(Sang-Duck Jeong),지경철(Kyoung-Chul Ji),정진희(Jin Hee Jeong) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.1
The present study has been conducted to propose an algorithm regarding real-time load estimation of a gas engine-driven heat pump. In the study, thermal load of an indoor unit is estimated in terms of air-side and refrigerant-side. The air-side estimation is based on a typical heat exchanger model and is found to be in good agreement with experimental data. When it comes to the refrigerant-side load, a pressure difference across a valve must be estimated. For the estimation, it is assumed to be proportional to a bigger pressure difference that is available either by measurement or by estimation. Relative good agreement between the air- and refrigerant- sides suggests that the assumption may be plausible for the load estimation. The summed flow rate of all of indoor units is in good agreement with the throughput of the compressor which are calculated from the manufacturer’s software. Accordingly, estimated thermal loads are also in good agreement. The proposed algorithm may be further developed for improved control algorithm and fault diagnosis.
Production of Liquiritigenin with Cell-based Biotransformation and Its Anti-Aging Activity
황혜진,정상철,박종필,Hwang, Hye Jin,Jeong, Sang Chul,Park, Jong Pil The Korean Society for Biotechnology and Bioengine 2015 KSBB Journal Vol.11 No.5
In this study, an efficient whole cell-based biotransformation for the production of liquiritigenin was developed using Laetiporus sulphureus CS0218 as biocatalyst and aqueous extracts of Glycyrrhiza uralensis as co-substrate, respectively. In order to determine the efficacy of this method, the optimal bioconversion conditions including mycelial growth, three important enzyme activities (${\beta}$-glucosidase, ${\alpha}$-rhamnosidase and ${\beta}$-xylosidase), and apparent viscosity of culture broth were monitored. After optimization, aqueous extracts of G. uralensis were added to the culture medium to directly produce algycone liquiritigenin. By applying this strategy, 67.5% of liquiritin was converted to liquiritigenin at pH 3.0 after 9 days of incubation and finally liquiritigenin was purified from the reaction mixture. And then, their biological activities including anti-oxidant and superoxide dismutase were observed. In fact, purified liquiritigenin was capable of bi-directional functions (i.e., either up-regulation or down-regulation of SIRT1 which is associated with aging). The results indicate that this strategy would be beneficial to produce biologically active liquiritigenin and could be used in pharmaceutical, cosmetic and food applications.