Design of T-S Fuzzy Model based Adaptive Fuzzy Observer and Controller

안창환 한국조명.전기설비학회 2009 조명·전기설비학회논문지 Vol.23 No.11

This paper proposes the alternative observer and controller design scheme based on T-S fuzzy model. Nonlinear systems are represented by fuzzy models since fuzzy logic systems are universal approximators. In order to estimate the unmeasurable states of a given unknown nonlinear system, T-S fuzzy modeling method is applied to get the dynamics of an observation system. T-S fuzzy system uses the linear combination of the input state variables and the modeling applications of them to various kinds of nonlinear systems can be found. The proposed indirect adaptive fuzzy observer based on T-S fuzzy model can cope with not only unknown states but also unknown parameters. The proposed controller is based on a simple output feedback method. Therefore, it solves the singularity problem, without any additional algorithm, which occurs in the inverse dynamics based on the feedback linearization method. The adaptive fuzzy scheme estimates the parameters and the feedback gain comprising the fuzzy model representing the observation system. In the process of deriving adaptive law, the Lyapunov theory and Lipchitz condition are used. To show the performance of the proposed observer and controller, they are applied to an inverted pendulum on a cart.

엔트로피에 의한 공동주택의 급수사용량에 관한 연구

안창환,공성훈,김종영 한국주거학회 2000 한국주거학회 논문집 Vol.11 No.3

The purpose of this study was to analyze water consumption in each apartment buildings influenced by several factors that are the income level of inhabitants, life style, the area apartments and climate. The automation of sanitary machines or facilities in recently built apartments has caused largely increases in amount of water consumption. Therefore, the design for water supply is very important for the maintenance of the optimum level or pressure of water supply. This study is based on the offer of basic data for improving the quality of water supply and employing the sanitary machines or sanitary facilities by analysis of amount increased of water consumption rapidly. Amount of water consumption data, the change in quality of entropy to the supply water pipe was analyzed and presented to indicate the necessary to basic materials for the design of an optimal water pipe.

공동주택에서 엔트로피에 의한 급수량에 관한 조사연구

안창환 대한기계설비건설협회 1999 기계설비 Vol.111 No.-

Calcium homeostasis in diabetes mellitus

안창환,강지훈,정의배 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.3

Diabetes mellitus (DM) is becoming a lifestyle-related pandemic disease. Diabetic patients frequently develop electrolyte disorders, especially diabetic ketoacidosis or nonketotic hyperglycemic hyperosmolar syndrome. Such patients show characteristic potassium, magnesium, phosphate, and calcium depletion. In this review, we discuss a homeostatic mechanism that links calcium and DM. We also provide a synthesis of the evidence in favor or against this linking mechanism by presenting recent clinical indications, mainly from veterinary research. There are consistent results supporting the use of calcium and vitamin D supplementation to reduce the risk of DM. Clinical trials support a marginal reduction in circulating lipids, and some meta-analyses support an increase in insulin sensitivity, following vitamin D supplementation. This review provides an overview of the calcium and vitamin D disturbances occurring in DM and describes the underlying mechanisms. Such elucidation will help indicate potential pathophysiology-based precautionary and therapeutic approaches and contribute to lowering the incidence of DM.

초고압 전력기기의 부분방전 인공지능 인식 알고리즘 적용 연구

안창환 한국조명.전기설비학회 2019 조명·전기설비학회논문지 Vol.33 No.4

In this study, a study was conducted to improve the defect recognition rate by converting the PRPS Raw-Data acquired in the event of partial discharge of high voltage power equipment into PRPD type and using the extracted parameter as input data of artificial intelligence algorithm. As a result, it was confirmed that sufficient recognition rate was obtained to accurately recognize the type of defect compared to the conventional partial discharge recognition method using the input image. Since it is much more advantageous in terms of computational speed than image recognition method, it is reasonable to use artificial intelligence algorithm method using parameter as a way to process vast signals generated in the field. There is no authorized regulation on the recognition rate of partial discharge measurements. The only recognition rate presented by the Korea Electric Power Corporation purchase specification is 90%. Considering this, the recognition rate obtained in this study is more than 99%, which shows that the learning speed and recognition rate are improved compared to the existing method.

엔트로피에 의한 수평급수관로 해석에 관한 연구

안창환,공성훈 대한건축학회 1999 대한건축학회논문집 Vol.15 No.3

Water is very useful to human life, and the importance of water supply system has been increased due to the environmental pollution This study defines the entropy as one of variable water flow rates on the horizontal water supply piping system in oiler to provide the satisfactory water supply system. Furthermore, in this study, theoretical interpretation and an experiment were carried out in order to calculate the optimum water pressure and diameter. A horizontal supply water piping system was equipped at the inside of a laboratory for the with a laboratory for the purpose of this experiment. Water flow rates, pressure, and velocity were measured with respect to the operation of faucets. From the measured data, the qualitative variation of entropy m the horizontal supply water piping system was analyzed and also it was suggested to the basic data for the optimum design of water piping system

토양의 유전율 특성을 고려한 정보통신설비용 수평접지전극의 임피던스 계산

안창환 대한전자공학회 2013 전자공학회논문지 Vol.50 No.11

An impedance of ground electrode for information and communication facilities has a significant relationship with the electrical characteristics of soil where the ground electrode is buried. Especially, the impedance of ground electrode is directly affected by the characteristics of permittivity and conductivity in soil as a function of a frequency of an applied electric field. The program based on the electromagnetic field model was developed in MATLAB. Because both permittivity and conductivity can not be modified in commercial programs. The permittivity of soil was applied with the Debye equation which is a model of dielectric relaxation. And the empirical equation of the conductivity in soil was quoted in other paper. In order to confirm the reliability of proposed program, the impedance measurement of ground electrode was carried out, which were compared with the results of simulation in commercial program. In result, it was confirmed that the impedance and phase different simulated by appling the characteristics of permittivity and conductivity in soil are in good agreement with the measured values than results of NEC. 정보통신설비용 접지전극의 임피던스는 접지전극이 매설되어 있는 토양의 전기적 특성과 밀접한 관계가 있다. 특히 인가된 전계의 주파수에 따른 토양의 유전율과 도전율 특성이 접지전극의 임피던스에 직접적으로 영향을 준다. 접지전극의 임피던스를 계산할 수 있는 상용프로그램은 유전율과 도전율을 수정하여 시뮬레이션하는 것이 불가능하기 때문에 전자계 이론을 적용한 프로그램을 MATLAB으로 구현하였다. 토양의 유전율은 유전완화 모델인 디바이(Debye)식을 적용하였으며, 도전율은 실험에서 얻어진 수식을 다른 논문에서 인용하였다. 시뮬레이션 결과의 신뢰성을 확인하기 위해서 실험계를 구성하여 접지전극의 임피던스를 측정하고, 시뮬레이션 결과와 서로 비교하였다. 그 결과, 토양의 유전율과 도전율 특성을 고려한 본 논문 결과가 고려하지 않은 상용프로그램(NEC) 결과 보다 측정값과 더욱 잘 일치하는 것을 확인하였다.

π-공액계 분자의 삼중항 여기 상태에 대한 Density Functional Theory (DFT)에 기반한 계산 방법들의 비교: 시간-의존 DFT (TD-DFT), Tamm-Dancoff 근사법을 적용한 DFT (TDA-DFT), 스핀-비제한 DFT (UDFT)

안창환,김동욱 대한화학회 2019 대한화학회지 Vol.63 No.2

We compared methodologies based on the density functional theory (DFT), e.g., time-dependent DFT (TD-DFT), TD-DFT within Tamm-Dancoff approximation (TDA-DFT), and spin-unrestricted DFT (UDFT), that are usually employed to optimize the geometries of π-conjugated molecules in their lowest lying triplet excited (T1) state. As a model system for π-conjugated molecules, we employed 1,2,3,4,5-pentacyano-6-phenyl-benzene. In conjunction with 6-31G(d) basis sets, we made use of gap-tuned range-separated ωB97X functional which is often employed recently in the calculations of molecular excited states. Near the equilibrium geometries, we found that the important difference between the geometries derived at UDFT level and those at TD-DFT or TDA-DFT methods: more stable ground-state energies but higher triplet excitation energies for UDFT derived geometries. In the studies, we discuss such differences in more detail. π-공액계 분자에 대해, density functional theory (DFT) 방법에 기반한 일반적인 삼중항 구조 최적화 방법들, 즉, 시간 의 존적 DFT (TD-DFT), Tamm-Dancoff 근사법에 기반한 TD-DFT (TDA-DFT), 그리고 스핀-비제한 DFT (UDFT)에 대한 점검을 수 행하였다. 모델 분자로서 1,2,3,4,5-pentacyano-6-phenyl-benzene가 이용되었고, 6-31G(d) 기저 함수와 더불어 여기 상태 계산에 최 근 자주 사용되는 에너지 차 조정 영역 분리 functional인 ωB97X functional이 사용되었다. 계산 결과 평형 구조 근처에서, UDFT 최적화된 구조는 TD-DFT 및 TDA-DFT 계산 구조와는 다른 차이점을 보인다. 즉, 보다 안정한 바닥 상태 에너지와 보다 높은 삼 중항 여기 에너지가 UDFT 최적화 구조에서 보인다. 본 논문에서는 이러한 차이에 대해 보다 자세히 토의된다.

엔트로피에 의한 수직급수관로 해석에 관한 연구

안창환,공성훈 대한건축학회 1999 대한건축학회논문집 Vol.15 No.6

The water supply system supplies very necessary water to human Iife. The reason is that recently the importance of water supply system has increased due to environmental pollution. This thesis interpreters entropy as water flow to supply water pipes for maintenance of optimal supply to the water environment. Furthermore, in this study, theoretical interpretation and an experiment were carried out in order to calculate the optimum water pressure and diameter. A vertical supply water piping system was equipped at the inside of a laboratory for the with a laboratory far the purpose of this experiment Water flow rates, pressure, and velocity were measured with respect to the operation of faucets. From the measured data, the qualitative variation of entropy in the vertical supply water piping system was analyzed and also it was suggested to the basic data for the optimum design of water piping system.

군사용 레이더 시스템 보호를 위한 낙뢰서지 방호장치의 설계

안창환 대한전자공학회 2023 전자공학회논문지 Vol.60 No.10

본 논문은 군사용 레이더 시스템에 적용되는 인버터의 출력단에 설치되어 낙뢰로 부터 인버터와 레이더 시스템을 보호하기 위한 새로운 서지 방호장치를 제안한다. 일반적으로 저압 배전계통에 사용되는 인버터는 입력측에 서지방호장치가 설치되어 있으나, 군사용 레이더 시스템에서는 인버터와 전동기가 물리적으로 떨어져 있기 때문에 구조물에 뇌격이 침입하면 인버터와 전동기에 연결된 케이블이 낙뢰전류의 유도 영향을 받게 된다. 따라서 이러한 구조적인 특성으로 인해 출력단에도 서지 방호장치가 필요하다. 또한, 저압 배전계통의 전원 주파수는 60Hz이지만, 인버터의 출력주파수는 PWM(Pulse Width Modulation) 제어를 통해 수 kHz로 출력된다. 따라서 인버터의 출력주파수는 서지 방호장치를 설계하고 적용하는데 반드시 고려해야 할 중요한 요소 중 하나이다. 본 연구에서는 이러한 고주파 환경에서 효과적으로 동작할 수 있는 새로운 서지 방호장치를 설계하고 잔류전압과 누설전류에 대한 동작 특성을 분석하였다. 본 연구의 결과는 유사한 조건에서 서지 방호장치를 설계하거나 선택할 때 유용한 정보를 제공할 것으로 기대된다. This paper proposes a new surge protective device that is installed at the output side of an inverter applied to military radar systems to protect the inverter and radar system from lightning strikes. Generally, inverters used in low-voltage distribution systems is installed surge protective devices on the input side, but military radar systems, the inverter and motor are physically separated. When a lightning strike invades the structure, the cables connected to the inverter and motor are influenced by the induced effects of lightning currents. Consequently, due to these structural characteristics, surge protective devices are also required at the output side. Additionally, while the power frequency of low-voltage distribution systems is 60Hz, the output frequency of the inverter is in the range of several kHz due to Pulse Width Modulation (PWM) control. Thus, the output frequency of the inverter is one of the crucial factors to consider when designing and implementing surge protective devices. In this study, we designed new surge protective devices capable of effectively operating under such high-frequency environment and analyzed their operational characteristics such as residual voltage and leakage current. The results of this study are expected to provide valuable information for designing and selecting surge protective devices under similar conditions.