Stability Analysis of Descriptor System Using Generalized Lyapunov Equation

오도창(Do-Chang Oh),이동기(Dong-Gi Lee) 대한전자공학회 2009 電子工學會論文誌-SC (System and control) Vol.46 No.4

이 논문에서는 특별한 형태의 일반화된 연속시간 Lyapunov 방정식과 해의 존재성에 대해 다룬다. 이것은 무한대의 고유치를 가지는 descriptor 시스템에 대해 시스템의 안정성을 분석하기 위해 필요하다. 주요결과로써 먼저 지수 1과 2를 가지는 경우의 descriptor시스템에 대해 안정성을 위한 필요충분조건을 먼저 제안하고 다음으로 일반적인 경우의 descriptor 시스템에 대하여 특별한 형태의 Lyapunov 방정식을 이용하여 비슷한 안정성 조건을 제안한다. 마지막으로 제안한 방법의 타당성을 보이기 위한 예제를 살펴본다. In this paper we consider the specific types of the generalized continuous-time Lyapunov equation and the existence of solution. This is motivated to analyze the system stability in situations where descriptor system has infinite eigenvalue. As main results, firstly the necessary and sufficient condition for stability of the descriptor system with index one or two will be proposed. Secondly, for the general case of any index, the similar condition for stability of descriptor system will be proposed with the specific type of the generalized Lyapunov equation. Finally some examples are used to show the validity of proposed methods.

전해액 중 Sodium silicate의 농도에 따라 양극 산화된 AZ31B 마그네슘 합금 양극 피막의 특성 평가

이동길(Dong-Kil Lee),김용환(Yong-Hwan Kim),박현(Hyun Park),정우창(Uoo-Chang Jung),정원섭(Won-Sub Chung) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.3

Magnesium is one of the lightest metals, and magnesium alloys have excellent physical and mechanical properties such as high stiffness/weight ratios, good castability, good vibration and shock absorption. However their poor corrosion resistance, wear resistance, hardness and so on, have limited their application. To improve these defects, many techniques are developed. Micro arc oxidation(MAO) is a one of the surface treatments under anodic oxidation in which ceramic coating is directly formed on the surface of magnesium alloy. In this study, the characteristics of anodic film were examined after coating the AZ31B magnesium alloy through the MAO process. MAO was carried out in potassium hydroxide, potassium fluoride, and various concentration of sodium silicate in electrolyte. The morphology and chemical composition of the coating layer were characterized by SEM, XRD, EPMA and EDS. The hardness of anodic films was measured by micro-vickers hardness tester. As a result, the morphology and composition of anodic film were changed by concentration of sodium silicate. Thickness and Si composition of anodic film was increased with increasing concentration of sodium silicate in electrolyte. The hardness of anodic film was highly increased when the concentration of sodium silicate was above 40 g/l in electrolyte.

특이시스템의 일반적 안정화

오도창(Do-Chang Oh),이동기(Dong-Gi Lee),김종해(Jong-Hae Kim) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.6

In this paper, we propose a generalized index independent stability condition for a descriptor systemwithout any transformations of system matrices. First, the generalized Lyapunov equation with a specific right-handed matrix form is considered. Furthermore, the existence theorem and the necessary and sufficient conditions for asymptotically stable descriptor systems are presented. Finally, some suitable examples are used to show the validity of the proposed method.

은 나노입자가 분산된 Honeycomb-patterned 수지 합성에 대한 연구

이동창(Dong Chang Lee),이종집(Jong Jib Lee) 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.2

Poly(N-vinylcarbazole) (PVK)-cellulose triacetate (CTA) 복합체를 합성하고, 필름에 기공을 형성시킨 뒤, 화학적 환원법을 통해 은 나노입자를 부착하는 것을 연구하였다. PVK-CTA 복합체는 CTA-chloroform 용액에서 iron(III) chloride를 산화제로 사용하여 N-vinylcarbazole을 중합시켜 복합체를 합성하였고, 얻어진 복합체를 습한 환경에서 휘발성용매로 적셔 수증기를 적용하여 macropore가 균일하게 형성된 구조인 Honeycomb-pattern을 형성시켰다. 이후 환원제로 Tetrathiafulvalene (TTF)와 분산제로 polyvinylpyrrolidone (PVP)를 사용하여 화학적 환원법을 이용해 은 나노입자를 Honeycomb-pattern이 형성된 복합체 표면에 부착시켰다. FT-IR과 UV-Vis spectrometer을 이용하여 복합체의 형성여부를 확인하였고, N-vinylcarbazole의 함량을 달리하여 중합한 뒤 복합체의 열 분해도를 측정하였다. Scanning electron microscope (SEM)을 통해 복합체 표면에 형성된 기공의 균일도와 부착된 은 나노입자들의 분산성을 분석하였으며, 환원제, 분산제, 전구체 용액의 농도를 달리하여 은나노입자의 분산성을 확인하였다. Silver nanoparticles were attached by chemical reduction after synthesizing a porous PVK-CTA complex. The PVK-CTA complex was synthesized by polymerizing N-vinylcarbazole in a CTA-chloroform solution using iron(III) chloride as an oxidizing agent and a honeycomb-pattern with uniformly formed macropores was formed by applying steam to the complex surface soaked with a volatile solvent under humid conditions. Using TTF as a reducing agent and PVP as a dispersant, silver nanoparticles were attached on the Honeycomb-pattern complex surface through chemical reduction. The formation of the complex was confirmed by FT-IR and UV-Vis spectrometry, and the degree of thermal decomposition of the complexes was analyzed after N-vinylcarbazole was polymerized by varying its concentration. The uniformity of the pores on the composite surface and the dispersibility of the attached silver nanoparticles were investigated by SEM. The dispersibility of the silver nanoparticles was also analyzed by varying the concentrations of reducing agent and dispersant and precursor.

동일 비료 장기시용시 벼 뿌리 특성 변화

전원태 ( Weon Tai Jeon ),박창영 ( Chang Young Park ),박기도 ( Ki Do Park ),조영손 ( Young Son Cho ),강위금 ( Ui Gum Kang ),이동창 ( Dong Chang Lee ),최진룡 ( Zhin Ryong Choe ) 한국토양비료학회 2002 한국토양비료학회 학술발표회 Vol.2002 No.1

평점 법에 의한 뇌졸중 예 후의 조기 판정기준에 관한 임상적 연구

장고창 ( Ko Chang Chang ),이동후 ( Dong Hoo Lee ),함준수 ( Joon Soo Hahm ) 대한내과학회 1978 대한내과학회지 Vol.21 No.2

야자각계 입상 활성탄의 Acid Black 1 염료 흡착에 대한 평형, 동역학 및 열역학 파라미터의 연구

이동창 ( Dong-chang Lee ),이종집 ( Jong-jib Lee ) 한국공업화학회 2016 공업화학 Vol.27 No.6

본 연구는 흡착제로 야자각계 수증기 활성화 입상 활성탄을 사용하여 Acid Black 1 수용액에서의 흡착 거동과 동역학적, 열역학적 파라미터에 대해 회분식 반응을 통해 조사하였다. 흡착변수로는 pH, 초기농도, 접촉시간, 온도를 사용하였다. pH에 대한 영향을 조사하기 위해 pHpzc 값을 분석한 뒤 pH 3-11 범위에서 제거율을 조사하였다. 흡착평형자료로부터 Langmuir, Freundlich, Temkin, Dubinin-Radushkevich 등온 흡착식에 대한 적합성을 평가하였다. 흡착공정에 대한 동역학적 해석을 통해 유사 1차반응식과 유사 2차반응식에 대한 흡착반응의 일치도를 평가하였다. 열역학적 해석을 통해 엔탈피 변화 값과 활성화에너지 값을 조사하여 이를 통해 흡착공정이 흡열반응인지를 확인하였으며, 엔트로피변화 값과 자유에너지 값을 통해 흡착공정의 자발성을 확인하였다. In this study, the adsorption behavior from aqueous solution as well as kinetic and thermodynamic parameters of Acid Black 1 were investigated through batch reaction using coconut shell based granular steam activated carbon. The effects of various adsorption parameters such as pH, initial concentration, contact time, temperature were studied. To confirm the effect of pH, pHpzc measurements were analyzed followed by measuring removal efficiencies of Acid Black 1 at the pH range from 3 to 11. Experimental equilibrium adsorption data were fitted using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich adsorption isotherm. The conformity of adsorption reaction for pseudo first and second order model were evaluated through kinetic analysis. Values of enthalpy change and activation energy were also investigated through thermodynamic analysis and it was confirmed that the adsorption process was endothermic. The spontaneity of adsorption process was evaluated using the values of entropy and Gibbs free energy changes.

골프장에서 등얼룩풍뎅이(Blitopertha orientalis)의 계절 및 지리적 발생

이동운,김재호,신종창,염주립,전재찬,신홍균,추호렬,Lee, Dong-Woon,Kim, Jae-Ho,Shin, Jong-Chang,Yeom, Ju-Rip,Jeon, Jae-Chan,Shin, Hong-Kun,Choo, Ho-Yul 한국잔디학회 2008 한국잔디학회지 Vol.22 No.1

Seasonal and regional occurrence of oriental beetle, Blitopertha (=Exomala) orientalis was investigated using pheromone traps and soil sampling at three golf clubs in Busan, Gunpo, and Gimpo from 2004 to 2007. Adults of Blitopertha orientalis were found from early June to late August, but peak times were different depending on the location and year. Peak day of adult occurrence of B. orientalis was 25 June,2006 and 22 June 2007 in Busan, but 30 June,2006 and 29 June,2007 in Gunpo. Mean numbers of B. orientalis adults attracted to pheromone trap varied with locations. Larval development was faster in Busan than in Gunpo. The 2nd instars of B. orientalis was found on 27 August, 2004 in Gunpo whereas 3rd instars were found in Busan in the same period. In Busan, overwintered 3rd instars pupated from early May to mid-June and emerged from early June. Eggs laid at this time were hatched from late June Most 3rd instars were found at middle August and started to overwinter. The peak time of mating was 20:00 to 22:00 hour of the day. 골프장 잔디의 주요 해충의 하나인 등얼룩풍뎅이의 발생상창을 알아보기 위하여 부산과 군포, 김포 지역의 골프장에서 토양 내에서의 발육경과와 페로몬트랩을 이용한 성충의 발생경과를 2004년부터 2007년까지 조사하였다. 등얼룩풍뎅이 성충의 발생은 6월 초순에서 8월 하순까지였는데, 성충의 발생 peak는 조사지역과 년도에 따라 차이가 있었다. 부산지역에서는 2006년 6월 25일에 발생 peak를 보였고, 2007년에는 6월 22일에 발생 peak를 보였는데 군포지역에서는 각각 6월 30일과 29일에 peak를 보였다. 페로몬트랩에 유인된 등 얼룩풍뎅이의 개체수는 조사 골프장별로 차이를 보였다. 등얼룩풍뎅이 유충의 발육경과도 부산지역이 군포지역에 비하여 빨랐는데 군포에서는 2004년 8월 27일 조사에서 2령충만 발견된데 비하여 부산지역에서는 같은 해 8월 26일에 조사한 것에서 2령충과 3령충이 함께 발견되었다. 부산지역에서 등얼룩풍뎅이의 발생경과는 월동한 3령 유충이 5월 초순에서 6월 중순까지 용화하였고, 6월 초순부터 우화하였다. 그리고 6월 하순부터 부화하였다. 8월 중순부터는 3령충이 되어 월동에 들어갔다. 등얼룩풍뎅이 성충의 교미 peak 시간은 20:00부터 22:00였다.

반도체 라인의 효율적 이상 감지를 위한 멀티에이전트 기반 시뮬레이터 도구의 개발

이동창(Dong-Chang Lee),조성배(Sung-Bae Cho) 한국정보과학회 2017 한국정보과학회 학술발표논문집 Vol.2017 No.06

회전형 초음파모터의 소형 위상차 제어기 개발

이동창(Dong Chang Yi),이선표(Sun Pyo Lee),이명훈(Myoung Hoon Lee),이의학(Euhark Lee) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.8

In this paper, a uniform speed controller for an ultrasonic rotary motor is developed using the phase-difference method. The phase difference method uses traveling waves to drive the ultrasonic motor. The traveling waves are obtained by adding two standing waves that have a different phase to each other. A compact phase-difference driver system is designed and integrated by combining VCO(Voltage Controlled Oscillator) and phase shifter. Theoretically the relationship between the phase difference in time and the rotational speed of the ultrasonic motor is sine function, which is verified by experiments. Then a series of experiments under various loading conditions are conducted to characterize the motor's performance that is the relationship between the speed and torque. Proportional-integral control is adopted for the uniform speed control. The proportional control unit calculates the compensating phase-difference using the rotating speed which is measured by an encoder and fed back. Integral control is used to eliminate steady-state errors. Differential control for reducing overshoot is not used since the response of ultrasonic motor is prompt due to its low inertia and friction-driving characteristics. The developed controller demonstrates reasonable performance overcoming disturbing torque and the changes in material properties due to continuous usage.