• 대한전자공학회논문지TC
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• 제45권4호
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• pp.9-21
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• 2008

이 논문은 위성항법시스템의 문제점들을 해결하기 위하여 GNSS 기반의 RF 수신단과 고정밀 측위 아키텍처 그리고 고감도 측위 아키텍처를 제안하였다. GNSS 기반의 RF 수신단 모델은 기존 GPS와 향후 사용되어질 갈릴레오의 항법정보데이터를 동시에 수신할 수 있는 구조를 가져야 한다. 따라서 GPS의 L1대역인 1575.42MHz와 갈릴레오의 El대역인 1575.42MHz, E5A대역인 1207.1MHz 그리고 E5B대역인 1176.45MHz를 동시에 수신할 수 있는 다중 밴드로 구성하였다. 고정밀 측위 아키텍처는 기존 상관기 구조가 가지고 있는 Early코드, Prompt코드, Late코드를 사용하는 1/2칩 이격 구조가 아닌 Early_early코드, Early_late코드, Prompt코드, Late_early코드, Late_late 코드 구조의 상관기를 제안하였다. 이렇듯 1/4칩 이격의 상관기 구조를 제안하여, 위성항법시스템으로부터 송신되는 신호의 부정확성으로 인해 생기는 C/A코드와의 동기 문제를 해결하였다. C/A코드와의 동기 문제는 차량용 항법시스템의 동기 획득 지연 시간 문제가 발생되어, 수신기의 성능 저하를 가져온다. 다음으로 고감도 측위 아키텍처는 20개의 코럴레이터(correlator)를 사용하여 비대칭 구조로 설계하여 수신 증폭률을 최대화하고, 잡음을 최소화하여 수신율을 향상시키도록 하였다. 위성항법시스템은 동일한 C/A코드를 20번 반복하여 전송한다. 따라서 동일한 C/A코드를 모두 사용할 수 있는 구조를 제안하였고, 적응형 구조를 가지고 있어, 주변 환경에 따라 코럴레이터의 수를 제한할 수 있어, 불필요한 시스템의 동작 지연 시간을 줄일 수 있다. 이러한 구조의 사용으로 동기 획득 지연 시간을 줄일 수 있고, 동기 추적의 연속성을 보장할 수 있다. 이는 위성항법시스템의 수신기 성능을 향상시키는 결과를 가져온다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.235-237
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• 2006

In this paper, the previous 2-D gradient coil design method using loop current elements is extended to 3-D or multi-layer structures which is useful for various MRI applications including MR microscopic imaging where relatively large space may be available for the implementation of the gradient coils. Either the power consumption or the stored energy (thus, inductance), or the combination of the two can be minimized with a set of chosen target field constraints. Complete 3-D design equations for the optimization as well as inductance or resistance calculation are derived. An effective coil shape correction method for a curved current pattern is also developed. The design method can also be easily extended to the active shielding structure.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.121.1-121
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• 2002

Calculation unit and peripheral units that are used to make the position controller are embedded to one chip FPGA. $\textbullet$ Feed-forward PID controller and interpolator in the calculation unit mitigate frequent context switching. $\textbullet$ The peripheral units reduce the size of the joints position control board. $\textbullet$ Because the calculation unit is designed with pipeline structure, it has the advantages to apply to the multi joints.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.454-455
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• 2018

The impedance of an underwater acoustic transducers constituting a multi-channel array structure could be changed in real time by various transmission modes. A power amplifier for driving the transducers usually use a voltage control method, so the transducer and power amplifier may be damaged by over-power due to changeable load conditions. Therefore, the drive controller of the power amplifier should have the function of limiting the power. This paper propose the new voltage control method for limiting the driving power of transducers with variable impedance characteristics.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1995년도 추계학술대회 학술발표 논문집
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• pp.11-14
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• 1995

A Fuzzy Classifier which deals with very confusing objects is proposed. Naturally this classifier heavily relies on the nulti-feature decision-making procedure. For a simple example, this classifier is applied to the recognition of confusing handwritten numerals 4,6 and 9 The characteristic variables used in this paper are the existence of a loop and the relative location of the starting or ending points(SEP). Thus each sample of handwritten numerals 4, 6 and 9 is classified in one of the 6 groups which are divided according to the sample structure. Each group has its own classifying rules. Also the method of rule-generation using genetic algorithms in each group is proposed.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.97-104
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• 2018

This paper proposes supplementary control of conventional coordinated control of a power plant which directly affects network frequency. The supplementary control with dynamic matrix control is applied for 1000 MW power plant with ultra-supercritical (USC) once-through boiler. The supplementary control signal is added to the boiler feedforward signal in the existing coordinated control logic. Therefore, it is a very practical structure that can maintain the existing multi-loop control system. This supplementary controller uses the step response model for the power plant system, and on-line optimization is performed at every sampling step. The simulation results demonstrate the effectiveness of the proposed supplementary control in a wide operating range of a practical 1000 MW USC power plant simulator. These results can contribute the stable operation of power system frequency.

• 한국자기공명학회논문지
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• 제25권3호
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• pp.39-44
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• 2021

The CRISPR-Cas system provides adaptive immunity for bacteria and archaea against invading phages and foreign plasmids. In the Class 1 CRISPR-Cas system, multi-subunit Cas proteins assemble with crRNA to bind to DNA targets. To disarm the bacterial defense system, bacteriophages evolved anti-CRISPR (Acr) proteins that actively inhibit the host CRISPR-Cas function. Here we report the backbone resonance assignments of AcrIF7 protein that inhibits the type I-F CRISPR-Cas system of Pseudomonas aeruginosa using triple-resonance nuclear magnetic resonance spectroscopy. We employed various computational methods to predict the structure and binding interface of AcrIF7, and assessed the model with experimental data. AcrIF7 binds to Cas8f protein via flexible loop regions to inhibit target DNA binding, suggesting that conformational heterogeneity is important for the Cas-Acr interaction.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.74-78
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• 2001

In this study, a multi-step optimization technique combined with a simple genetic algorithm is introduce to the structural design optimization of a high speed machining center. In this case, the design problem is to find out the best design variables which minimize the static compliance, the dynamic compliance, and the weight of the machine structure and meet some design constraints simultaneously. Dimensional thicknesses of the thirteen structural members along the static force loop of the machine structure are adopted as design variables. The first optimization step is a static design optimization, in which the static compliance and the weight are minimized under some dimensional and safety constraints. The second step is a dynamic design optimization, where the dynamic compliance and the weight are minimized under the same constraints. After optimization, the weight of the moving body was reduced to 9.1% of the initial design respectively. Both static and dynamic compliances of the optimum design are also in the feasible range even thought they were slightly increased than before.

• 한국전자파학회논문지
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• 제21권5호
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• pp.475-485
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• 2010

본 논문에서는 여파기와 안테나 기능을 동시에 수행할 수 있는 새로운 개념의 마이크로스트립 공진기를 제안하고자 한다. 제안한 구조는 바깥쪽 링, 안쪽 링, 원형 패치, 그리고 3개의 포트로 이루어져 있다. 제안하는 구조가 여파기와 안테나로 동작하는 주파수는 각각 주로 안쪽 링과 원형 패치의 반지름에 의해 결정된다. 측정 결과를 통해 마이크로스트립 공진기가 여파기로 동작할 경우 공진 주파수는 0.69 GHz에서 3 dB 대역폭 15.1 %에 삽입 손실이 -1.4 dB의 특성을 보였다. 이 때, 통과 대역 아래 부분에 전달 영점은 0.52 GHz에, 윗부분의 전달 영점은 1.14 GHz와 2.22 GHz에 위치하였다. 위쪽 저지 대역에서 바깥쪽 링의 스터브에 의한 교차 결합(cross coupling)과 안쪽 링에 의해 각각 1개의 전달 영점이 형성된다. 원형 패치는 이중 모드(dual-mode) 특성을 형성하며, 또 다른 전달 영점을 유도한다. 제안한 구조가 안테나로 동작하는 주파수는 2.7 GHz이고, 이득은 3.8 dBi 였다. 여파기와 안테나의 공진 주파수에서 격리도 특성(isolation)이 각각 -25 dB 이하의 좋은 특성을 나타내었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.289-290
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• 2006

In general, atomic force microscope (AFM) used for metrological purpose has measuring range less than a few hundred micrometers. We design and fabricate an AFM with long measuring range of $200mm{\times}200mm$ in X and Y axes. The whole stage system is composed of surface plate, global stage, microstage. By combining global stage and microstage, the fine and long movement can be provided. We measure the position of the stage and angular motions of the stage by laser interferometer. A piezoresistive type cantilever is used for compact and long term stability and a flexure structure with PZT and capacitive sensor is used for Z axis feedback control. Since the system is composed of various actuators and sensors, a real time control program is required for the implementation of AFM. Therefore, in this work, we designed a multi-axis control program using a FPGA module, which has various functions such as interferometer signal converting, PID control and data acquisition with triggering. The control program achieves a loop rate more than 500 kHz and will be applied for the measurement of grating pitch and step height.