• Journal of the Korean Data and Information Science Society
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• 제26권4호
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• pp.907-914
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• 2015

저출산으로 인한 학생수의 감소는 교육 행정 정책에 있어서 매우 많은 변화들을 예고하고 있다. 본 연구는 2032년까지 정확한 학생 (인구) 수를 예측하기 위하여 연령 진급률 혹은 학년 진급률을 이용한 학생 (인구) 수를 추계하는 방법을 제시하는데 목적이 있다. 비례법을 이용한 이동평균비례법과 가중비례이동평균법이 인구추계의 방법으로 제시되었다. 제시된 방법들의 측정오차들에 대한 평균과 표준편차들을 모의실험을 통하여 구하였다. 본 연구에서 제시된 가중비례이동평균법과 이동평균비례법의 예측결과들은 낮게 추정되는 현상이 나타나고 있다. 이를 보완하여 대구 경북 지역의 고등학교 3학년 학생수를 추계하였다.

• Journal of the Korean Data and Information Science Society
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• 제21권3호
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• pp.503-511
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• 2010

본 연구의 목적은 연령진급률 혹은 학년진급률을 추정하기 위한 방법으로 비례법을 사용한 이동평균법에 의한 알고리즘을 제시하는데 있다. 학년진급률에 따른 학생 수 추계방법으로, 이동평균법과 비례이동평균법에 의한 추정방법을 제시하고, 2027년까지의 서울시의 고3학생 수를 추정하여, 한국교육개발원의 2005년, 2006년, 2007년의 로지스틱함수 추정에 의한 고3학생 수 예측결과와 비교 분석하였다. 본 연구의 결과 출생아수의 분포와 비교하여 볼 때, 본 연구에서 제시된 비례이동평균법과 이동평균법의 예측결과가 한국교육개발원의 2005년, 2006년, 2007년의 고3학생 수의 예측결과보다 더 신뢰성이 있는 것으로 나타난다.

• 소음진동
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• 제8권3호
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• pp.441-449
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• 1998

A self-tuning control scheme, incorporated with the simplified 1st-order ARMAX(Auto-Regressive Moving Average eXogenous) model, for single rod hydraulic cylinder which has varying dynamic characteristics is presented here. An adaptive controller is developed for the system that uses feedforward and optimal feedback control for simultaneous parameter identification and tracking control. Through experimental results, the performance comparison of the self-tuning controller with a fixed gain proportional controller clearly shows its superior ability in handling load changes in quiescent states.

• 천문학회보
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• 제40권1호
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• pp.50.1-50.1
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• 2015

We present a new hydrodynamic simulation based on the unstructured moving mesh scheme. The simulation utilizes the Voronoi tessellation technique that produces polygonal cells composed of, on average, 13 surfaces each in 3D. We devise the incremental expanding method (IEM) and hybrid-neighbor searching algorithm and achieve the CPU time just proportional to the number of particles, i.e., O(N). We show the results of requisite tests for hydrodynamic simulations and demonstrate superiority of our code over the conventional codes using the stationary meshes. The applications in the context of cosmological and galactic simulations are also discussed.

• Journal of Welding and Joining
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• 제15권1호
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• pp.81-91
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• 1997

In this study, a magnetic sensor to make use of eddy current was developed to detect the weld seam of butt joint in the sheet metal arc welding. This system consist of the sensor device for detecting the weld line, the servo control device for driving the weld torch movement and the control unit. A signal processing was applied to smooth the output signal of the sensor. The weld joint was determined by using a 1st order differential method. To improve tracking accuracy of the system, moving average method which has an effect of proportional and weighted integral control was applied to a series of the weld joint positions obtained above. The weld line for tracking was generated by using data regeneration algorithm. Based on these results, each servo motor was controlled by pulse generator. From experimental results, it was revealed that this system has excellent detecting ability for weld line and seam tracking ability.

• Journal of Power Electronics
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• 제11권5호
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• pp.751-758
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• 2011

This paper presents an effective robust predictive control scheme for the active power filter (APF) using a smith-predictor based current regulator, which show superior features when compared to proportional-integral (PI) controllers in terms of an enhanced closed-loop bandwidth and an improved current tracking accuracy. A moving average filter (MAF) is implemented using a field programmable gate array (FPGA) for signal pre-processing to eliminate the switching ripple contamination. An adaptive linear neural network (ADALINE) is used for individual harmonic estimation to achieve selective compensation purpose. The effectiveness and validity of the devised control algorithm are confirmed by extensive simulation and experimental results.

• 한국컴퓨터정보학회논문지
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• 제25권12호
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• pp.35-44
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• 2020

본 연구에서는 주가 결정 방법이 주가 경향 예측에 미치는 영향을 확인하기 위한 분석을 수행한다. 주식시장에서 성공적인 투자를 위해서는 주가의 상승과 하락을 정확하게 예측하는 것이 큰 도움이 되므로 주가 경향 예측에 관해 많은 연구가 진행되고 있다. 예를 들어 근래에는 SNS나 뉴스의 내용을 텍스트 마이닝을 이용하여 분석하고, 이를 이용한 주가 등락의 예측 방법이 제안되었으며 다양한 기계학습 기법들이 활용되고 있다. 그러나 주가의 경향을 '상승' 또는 '하락'으로 결정하는 방법은 제대로 분석된 적 없으며 일반적으로 쓰던 방법을 답습하고 있다. 이에 본 논문에서는 주가 경향 결정 방법을 이동평균을 이용해 일반화하고 주가 경향 결정 방법이 예측 정확도에 미치는 영향을 분석한다. 분석 결과, 다음 날의 주가 경향을 예측하는 경우, 주가 경향 결정방법에 따라 예측 정확도가 47%까지 차이가 남을 발견하였다. 또한 경향 결정에 사용되는 기준값 윈도우의 크기와 예측의 정확도는 비례 관계이며, 대상값 윈도우의 크기와 정확도는 반비례 관례임을 알 수 있었다.

• Journal of Forest and Environmental Science
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• 제38권4호
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• pp.239-248
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• 2022

Forestry crane work in a forest harvester or forwarder is regarded as one of most hard work requiring a very high level of operation skill. The operator must handle two or more multi-axes joysticks simultaneously to control the multiple manipulators for maneuvering the crane-tip to its intended location. This study has been carried out to develop a crane-tip controller which can intuitively maneuver the crane-tip, resulting in improving the productivity by decreasing the technical difficulty of control as well as reducing the workload. The crane-tip controller consists of a single 2-axis joystick and a control algorithm run on microcontroller. Lab-scale forestry crane was constructed using electric cylinders. The crane-tip control algorithm has the crane-tip follow the waypoints generated on the given path considering the dead band region using LBO (Lateral Boundary Offset). A speed control gain to change the speed of relevant cylinders relatively is applied as well. By the P (Proportional) control within the control interval of 20 msec, the average error of crane-tip control on the predefined straight path turned out to be 14.5 mm in all directions. When the joystick is used the waypoints are generated in real time by the direction signal from the joystick. In this case, the average error of path control was 12.4 mm for straight up, straight forward and straight down movements successively at a certain constant speed setting. In the slant movement of crane-tip by controlling two axes of joystick simultaneously, the movement of crane-tip was controlled in the average error of 15.9 mm when the crane-tip is moved up and down while moving toward forward direction. It concluded that the crane-tip control was possible using the control algorithm developed in this study.

• 한국정밀공학회지
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• 제30권8호
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• pp.831-838
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• 2013

This paper focused on the design of an efficient temperature controller for a plant with a wide range of operating temperatures. The greater the temperature difference a plant has, the larger the nonlinearity it is exposed to in terms of heat transfer. For this reason, we divided the temperature range into five sections, and each was modeled using ARMAX(auto regressive moving average exogenous). The movement of the dominant poles of the sliced system was analyzed and, based on the variation in the system parameters with temperature, optimal control parameters were obtained through simulation and experiments. From the configurations for each section of the temperature range, a temperature-based gain-scheduled controller (TBGSC) was designed for parameter variation of the plant. Experiments showed that the TBGSC resulted in improved performance compared with an existing proportional integral derivative (PID) controller.

• 한국미생물·생명공학회지
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• 제21권4호
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• pp.354-365
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• 1993

A novel control method with automatic tuning of PID controller parameters has been developed for efficient regulation of dissolved oxygen concentration in fed-batch fermentations of Escherichia coli. Agitation speed and oxygen partial pressure in the inlet gas stream were chosen to be the manipulated variables. A heuristic reasoning allowed improved tuning decisions from the supervision of control performance indices and it coule obviate the needs for process assumptions or disturbance patterns. The control input consisted of feedback and feedforword parts. The feedback part was determined by PID control and the feedforward part is determined from the feed rate. The proportional gain was updated on-line by a set of heuristics rules based on the supervision of three performance indices. These indices were output error covariance, the average value of output error, and input covariance, which were calculated on-line using a moving window. The integral and derivative time constants were determined from the period of output response. The specific growth rate was maintained at a low level to avoid acetic acid accumulation and thus to achieve a high cell density. The specific growthe rate was estimated from the carbon dioxide evolution rate. In fed-batch fermentation, the simutaneous control of dissolved oxygen concentration (at 0.2; fraction of saturated value) and specific growth rate (at 0.25$hr^{-1}$) was satisfactory for the entire culture period in spite of the changes in the feed rate and the switching of control input.