• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3124-3126
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• 2000

The application of IR(Infrared) communication is very wide and IR receiver has become a standard of home entertainment. A preamplifier with single 5V supply was designed for IR receiver IC. To operate at long distance, receiver IC should have high gain and low noise characteristic. To provide constant output signal magnitude, independent of transciever distance, gain limiting stage is needed. And to cut-off DC noise component effectively, large resistance and capacitance are required. Transimpedance type preamplifier, and diode limiting amplifier, and current limiting amplifier were designed. It is another function of current limiting amplifier that transforms single input signal to differential output signal. Using AMS BiCMOS model, both BJT version and MOS version was designed. Total power consumption is O.lmW, and IC size is $0.3mm^2$

• Computers and Concrete
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• 제15권1호
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• pp.127-140
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• 2015

The process of chloride ingress in saturated concrete was presented by a previous study that used a mathematical model for the same as that concrete. This model is to be studied chloride ion diffusion which is considered as a chemical phenomenon and is to be represented the chloride diffusion process to be a nonlinear partial differential equation (PDE). In this paper, this nonlinear PDE is solved by the Kirchhoff transformation to render into a linear PDE. This linear PDE associated with initial and boundary conditions is also solved by the Laplace transformation to obtain an analytical solution. To verify the serviceability and reliability of this proposed method, the practical application should be supplied. The input parameters were cited from the previous study. The free chloride concentration profiles obtained by the analytical solution of mathematical model for saturated concretes after 24 and 120 hrs of exposure were compared with the previous study. The predicted results obtained from proposed method have a tendency with experimental results obtained by the previous study and trend toward numerical results approximated by finite difference technique.

• Structural Engineering and Mechanics
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• 제36권5호
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• pp.561-573
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• 2010

The potential of the liquid column vibration absorber (LCVA) as a seismic vibration control device for structures has been explored in this paper. In this work, the structure has been modeled as a linear, viscously damped single-degree-of-freedom (SDOF) system. The governing differential equations of motion for the damper liquid and for the coupled structure-LCVA system have been derived from dynamic equilibrium. The nonlinear orifice damping in the LCVA has been linearized by a stochastic equivalent linearization technique. A transfer function formulation for the structure-LCVA system has been presented. The design parameters of the LCVA have been identified and by applying the transfer function formulation the optimum combination of these parameters has been determined to obtain the most efficient control performance of the LCVA in terms of the reduction in the root-mean-square (r.m.s.) displacement response of the structure. The study has been carried out for an example structure subjected to base input characterized by a white noise power spectral density function (PSDF). The sensitivity of the performance of the LCVA to the coefficient of head loss and to the tuning ratio have also been examined and compared with that of the liquid column damper (LCD). Finally, a simulation study has been carried out with a recorded accelerogram, to demonstrate the effectiveness of the LCVA.

• 한국전자통신학회논문지
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• 제8권10호
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• pp.1477-1483
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• 2013

연속시간 전류모드 기저대역 채널선택 필터 설계를 위하여 전류이득과 단위이득 주파수를 개선시킨 저전압 선형 캐스코드 전류모드 적분기를 제안하였다. 제안된 전류모드 적분기는 CMOS 상보형 회로로 구성된 완전 차동 형태의 입 출력단으로 구성하였으며, 여기에 캐스코드 트랜지스터를 추가시킴으로써 바이어스 단을 구성하여 선형영역에서 동작시켜 저전압 구조에 적합하도록 설계하였다. 이 때 바이어스 전압을 선택적으로 제어하여 주파수 대역이 가변될 수 있도록 설계하였다. 시뮬레이션 결과를 통해 설계한 선형 캐스코드 전류모드 적분기가 저전압 동작, 전류 이득 및 단위이득 주파수 등 모두 만족할 만한 특성을 가지고 있음을 확인하였다.

• 대한전기학회논문지:전력기술부문A
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• 제55권3호
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• pp.116-122
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• 2006

The underground transmission lines is continuously expanded in power systems. Therefore the fault of underground transmission lines are increased every year because of the complication of systems. However the studies dealing with fault location in the case of the underground transmission lines are rarely reported except for few papers using traveling wave method and calculating underground cable impedance. This paper describes the algorithm using fuzzy system and travelling wave method in the underground transmission line. Fuzzy inference is used for fault discrimination. To organize fuzzy algorithm, it is important to select target data reflecting various underground transmission line transient states. These data are made of voltage and average of RMS value on zero sequence current within one cycle after fault occurrence. Travelling wave based on wavelet transform is used for fault location. In this paper, a variety of underground transmission line transient states are simulated by EMTP/ATPDraw and Matlab. The input which is used to fault location algorithm are Detail 1(D1) coefficients of differential current. D1 coefficients are obtained by wavelet transform. As a result of applying the fuzzy inference and travelling wave based on wavelet transform, fault discrimination is correctly distinguished within 1/2 cycle after fault occurrence and fault location is comparatively correct.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.227-230
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• 1993

Recently, the development of novel control methodology enables us to improve the performance of AC-machine drives by using pulse width modulation (PWM) technique. Usually, the dynamic characteristic of induction motor (IM) has been represented by the 5-th order nonlinear differential equation. This dynamics, however, can be reduced to 3-rd order dynamics by applying direct control of IM input current. This methodology concludes that it is much easier to control IM by means of the field-oriented methods employing the current controller. Therefore a precise current control is crucial to achieve a high control performance both in dynamic and steady state operations. This paper presents an adaptive fuzzy current controller with artificial neural network (ANN) for field-oriented controlled IM. This new control structure is able to adaptively minimize a current ripple while maintaining constant switching frequency. Especially the proposed controller employs neuro-computing philosophy as well as adaptive learning pattern recognizing principles with respect to variations of the system parameters. The proposed approach is applied to the IM drive system, and its performance is tested through various simulations. Simulation results show that the proposed system, compared among several known classical methods, has a superb performance.

• 한국정보통신학회논문지
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• 제11권6호
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• pp.1176-1181
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• 2007

본 연구에서는 플랜트의 잡음, 부하, 및 변경된 파라미터를 제어하는 퍼지 PI+퍼지 D제어기 즉, 일종의 강인한 제어 시스템을 고려하고자 한다. 차분 방정식에 대하여 PI+D제어기를 적용하였으며 PI+D제어기의 PID 파라미터에 대응 입력에 대한 퍼지 제어기를 계획하고 따라서 파라미터 변화에 따른 환경 변화에 강인한 제어 시스템을 설계하였다. 퍼지제어는 편리한 4가지 규칙과 멥버쉽 함수를 가지고 있다. 본 연구에서는 3상의 유도 모터 제어에 대하여 퍼지 PI+퍼지 D제어기를 설계하고 그 성능을 검증하였다.

• 한국유기농업학회지
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• 제30권4호
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• pp.485-497
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• 2022

Agricultural environmental policies to reduce negative externalities and expand positive externalities became common around the world. However, literature regarding the efficient and effective implementation of agricultural environmental policies, such as optional direct payment, is limited. This study, thus, analyzes the relative importance for target selecting-criteria in order to enhance the cost-effectiveness of the Agricultural Environment Conservation Program in Korea. In this context, we conducted survey to 15 experts who are related in agricultural environment policies and analyzed survey results based on ANP method which can consider correlation between selecting criteria. The results show that, in the case field, "soil", "water", and "ecology" field have relative high importance than the other fields. Also, the relative importance for 'improving rural landscape', 'giving nutrient input moderately', and 'conserving agricultural heritage' activities is higher than the other activities. Furthermore, the relative importance among fields and activities of ANP is different from those of AHP. This result implies that it is necessary to consider the correlation between selecting criteria in order to design effectively. Finally, we suggest that in order to enhance the effectiveness of the program, it would be appropriate to assign differential points according to the importance of each activity when identifying appropriate farms.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.100-108
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• 2023

In this study, a neural network model inspired by a one-dimensional convolution U-net is developed to automatically accelerate edge localized mode (ELM) detection from big diagnostic data of fusion devices and increase the detection accuracy regardless of the hyperparameter setting. This model recognizes the input signal patterns and overcomes the problems of existing detection algorithms, such as the prominence algorithm and those of differential methods with high sensitivity for the threshold and signal intensity. To train the model, 10 sets of discharge radiation data from the KSTAR are used and sliced into 11091 inputs of length 12 ms, of which 20% are used for validation. According to the receiver operating characteristic curves, our model shows a positive prediction rate and a true prediction rate of approximately 90% each, which is comparable to the best detection performance afforded by other algorithms using their optimized hyperparameters. The accurate and automatic ELM-burst detection methodology used in our model can be beneficial for determining plasma properties, such as the ELM frequency from big data measured in multiple experiments using machines from the KSTAR device and ITER. Additionally, it is applicable to feature detection in the time-series data of other engineering fields.

• 한국콘텐츠학회논문지
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• 제11권9호
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• pp.238-245
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• 2011

지방자치제도의 도입은 지역주민의 요구에 따른 공공서비스의 효율적 공급을 가능하게 하였다. 특히, 자치단체는 지역주민의 복지증진을 위한 다양한 정책과 많은 예산을 편성하는 등의 노력을 하고 있으나, 사회복지 재정의 효율적 사용과 운영에는 상대적으로 관심을 적게 가지고 있다. 이러한 문제점에 따라 본 연구는 전국 16개 광역 자치단체의 사회복지시설 운영의 효율성을 측정하기 위해 자료포락분석(DEA)을 실시하였다. 투입변수는 1인당지역내총생산, 일반회계중복지예산비율, 재정자립도, 만명당사회복지전담공무원수, 산출변수로는 유아천명당보육시설수, 10만명당사회복지시설수, 천명당공원면적으로 하였다. 분석 결과는 다음과 같다. 첫째, 자치단체별 사회복지시설의 효율성에 격차가 있었다. 7개 자치단체가 비효율적이었으며, 부산과 충남이 상대적으로 효율성이 낮게 나타났다. 둘째, 규모수익불변인 DMU는 9개 자치단체이며, 인천, 광주, 강원은 투입요소의 규모를 늘려 각 자치단체의 효율성을 증가시켜야 하며, 부산, 충남, 경남, 경북은 투입요소의 효율성 향상방안을 수립하여야 하는 것으로 나타났다.