• 한국정보통신학회논문지
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• 제25권12호
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• pp.1846-1852
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• 2021

현대 사회는 4차 산업혁명과 IoT 기술의 발전으로 폭넓은 분야에 다양한 디지털 기기들이 보급되고 있다. 하지만 영상을 획득하거나 전송하는 과정 등에서 잡음이 발생하여 정보를 훼손할 뿐 아니라, 시스템에 영향을 끼쳐 오류와 잘못된 동작을 일으킨다. 영상 잡음 중 대표적인 잡음으로 AWGN이 있다. 잡음을 제거하기 위한 방법으로 선행연구가 진행되어져 왔고 그 중 대표적인 방법으로 AF, A-TMF, MF 등이 있다. 기존의 필터들은 영상의 특성을 고려하기 어려워 고주파 성분이 많은 영역에서는 스무딩 현상이 발생한다는 단점이 있다. 따라서 제안한 알고리즘은 고주파영역에서도 효과적으로 잡음을 제거하기 위해 표준편차 분포도를 구한 후, 커브 피팅 방식을 이용한 라플라스 분포의 확률밀도함수 가중치를 적용하여 최종 출력을 구한다.

• Advances in Energy Research
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• 제5권1호
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• pp.31-55
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• 2017

In the present study, PV/T collector was modeled via analysis of governing equations and physics of the problem. Specifications of solar radiation were computed based on geographical characteristics of the location and the corresponding time. Temperature of the collector plate was calculated as a function of time using the energy equations and temperature behavior of the photovoltaic cell was incorporated in the model with the aid of curve fitting. Subsequently, operational range for reaching to maximal efficiency was studied using Genetic Algorithm (GA) technique. Optimization was performed by defining an objective function based on equivalent value of electrical and thermal energies. Optimal values for equipment components were determined. The optimal value of water flow rate was approximately 1 gallon per minute (gpm). The collector angle was around 50 degrees, respectively. By selecting the optimal values of parameters, efficiency of photovoltaic collector was improved about 17% at initial moments of collector operation. Efficiency increase was around 5% at steady condition. It was demonstrated that utilization of photovoltaic collector can improve efficiency of solar energy-based systems.

• Smart Structures and Systems
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• 제22권3호
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• pp.359-368
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• 2018

A method is proposed for the identification of instantaneous frequencies (IFs) in time-varying structures. The proposed method combines a maximum gradient algorithm and a smoothing operation. The maximum gradient algorithm is designed to extract the wavelet ridges of response signals. The smoothing operation, based on a polynomial curve fitting algorithm and a threshold method, is employed to reduce the effects of random noises. To verify the effectiveness and accuracy of the proposed method, a numerical example of a signal with two frequency modulated components is investigated and an experimental test on a steel cable with time-varying tensions is also conducted. The results demonstrate that the proposed method can extract IFs from the noisy multi-component signals and practical response signals successfully. In addition, the proposed method can provide a better IF identification results than the standard synchrosqueezing wavelet transform.

• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.149-156
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• 2011

This paper reveals a distance estimation algorithm based on multi-code ultrasonic and wireless sensor network. For measuring the distances among the sensor nodes, each ultrasonic transmitter transmits multi-code ultrasonic signal simultaneously. Receivers use cross correlation method to separate the coded signals. The information of measured distances is broadcasted to each sensor node by wireless sensor network. The wireless sensor network measures the distance among the sensor nodes using the received signal strength of the broadcasting. The multi-code ultrasonic have a limitation of measurable distance. And the received signal strength is affected from an environment. This paper measures a distance using ultrasonic and a received signal strength in short range. These measured data are applied to the least square estimation algorithm. By the expansion of the fitting curve, a distance measurement in long range using the received signal strength is compensated. The coupled system reduce the error to an acceptable level.

• 한국전자파학회논문지
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• 제23권10호
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• pp.1212-1215
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• 2012

레이다 간섭계에서 표적의 공간 도달 각도를 추정하는 방법 중에서 위상 비교 모노 펄스 알고리즘의 추정 각도 정확도를 향상시키기 위한 위상평균법 및 시간 지연 보상 방안을 제안하였다. 실시간 신호처리 시스템에 적용할 경우, 저역 통과 필터의 특성을 갖는 위상평균법을 적용하면 필연적으로 시간 지연이 발생한다. 이 문제점을 보완하기 위해 곡선 맞춤법을 이용하여 추정된 각도의 변화율을 계산하고 보상하여 실시간 신호처리 시스템에 적용 가능하도록 하였다. 제안 방법의 효용성을 입증하기 위해 실제 레이다 간섭계를 이용하여 획득된 데이터에 적용하여 추정된 각도의 정확도를 비교하였다.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.171-180
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• 2001

Collision accident reconstruction algorithm are developed based on the deformation shape and severity of a car body. At first, the body stiffness equation representing the force-deformation relationship is derived using finite element analysis for head on collision of two cars. The database of deformation shapes and energies is constructed for five different collision configurations; each configuration contains three velocity conditions. Deformation shapes are obtained using a curve fitting method and result in cubic polynomials. Deformation energies are calculated using a stiffness equation and deformation data. Three algorithms are developed to reconstruct collision configuration compared with constructed database. The developed algorithms show reasonably good performance to find collisions conditions for some test problems.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.19-20
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• 2017

본 논문에서는 자성체 및 비자성체 용기 판별이 가능하고 워킹코일 온도 변화가 고려된 All Metal IH(Induction Heating) 제어 알고리즘을 설계한다. 용기 재질과 위치에 따른 파라미터를 분석하여 전력 Curve-fitting 모델링을 통해 용기 판별을 수행하고 비자성체 가열 시 급상하는 워킹코일 온도를 반영하여 변화하는 전력 제어 알고리즘을 보상한다. 설계된 All Metal IH 제어 알고리즘은 실험을 통해 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.22-24
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• 2002

This paper introduces the real-time soil thermal property analyzer and temperature measuring system which is combined with radio telecommunication technique. To measure the thermal parameters in real-time, the radio telecommunication technique are used the personal communication service (PCS) which is in the world-wide serviced commercially firstly by CDMA. The thermal property analyzer has an ability of measuring thermal resistivity, thermal diffusivity and thermal stability. To estimate the soil thermal properties, the curve fitting algorithm by means of the least square method are used. TCP/IP protocol and MTM are used to install the real-time soil thermal property and temperature measurement system at multiple locations along routes of the underground power cables and to reduce the cost of telecommunication.

• 대한기계학회논문집A
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• 제25권4호
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• pp.748-755
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• 2001

This paper concerns rotor vibration reduction using magnetic damper system. The fuzzy control logic is utilized to fulfill desired motion. The fuzzy system structure and membership function were first determined by simulation results. The researched control logic contains two fuzzy controller : reference position variation according to the rotor whirling status and error compensation algorithm to minimize the rotor vibration due to unbalance and unstable fluid film force. The Sugeno type output membership function was utilized by several trials and optimized membership function constants were selected from experiments. The experimental results show that the proposed method effectively control and reduce the rotor vibration with fluid film bearings.

• 반도체디스플레이기술학회지
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• 제2권2호
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• pp.9-15
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• 2003

This paper proposes a thickness measurement method of silicon-oxide and poly-silicon film deposited on 12" silicon wafer for spin etcher. Halogen lamp is used as a light source for generating a wide-band spectrum, which is guided and focused on the wafer surface through a optical fiber cable. Interference signal from the film is detected by optical sensor to determine the thickness of the film using spectrum analysis and several signal processing techniques including curve-fitting and adaptive filtering. Test wafers with three kinds of priori-known films, polysilicon(300 nm), silicon-oxide(500 nm) and silicon-oxide(600 nm), are measured while the wafer is spinning at 20 Hz and DI water flowing on the wafer surface. From experiment results the algorithm presented in the paper is proved to be effective with accuracy of maximum 0.8% error.rror.