• 센서학회지
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• 제28권5호
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• pp.323-328
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• 2019

Recently, a sound wave phase meter (SWPM) that can directly measure the pressure waveform of sound waves in free space has been reported, and the development of educational experimental equipment using this meter is in progress. One of the main advantages of using this meter is that wavelengths can be obtained directly from the crests and troughs of the measured pressure waveforms in space without expensive equipment. However, there are times when the measurement wavelength does not exactly match the actual wavelength value, and the pressure waveform differs from the actual shape. This study was conducted to identify and analyze the causes of such errors occurring in SWPM. As a result, it was found that wavelength errors occur when the propagation direction of sound waves and the measurement direction of SWPM do not coincide. It has also been found that an error in the pressure waveform is generated when the induction and sound wave signal outputs from the SWPM interfere with each other to produce a composite signal. We have shown that we can develop educational experimental equipment by suggesting ways to reduce such errors.

• Journal of Power Electronics
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• 제19권2호
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• pp.333-343
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• 2019

Dead time and the nonideal characteristics of components all lead to phase voltage distortions. In order to eliminate the harmful effects caused by distortion, numerous methods have been proposed. The efficacy of a method mainly depends on two factors, the compensation voltage amplitude and the phase current polarity. Theoretical derivations and experiments are given to explain that both of these key factors can be deduced from the compensation time, which is defined as the error time between the ideal phase voltage duration and the actual phase voltage duration in one Pulse Width Modulation (PWM) period. Based on this regularity, a novel method for compensating phase voltage has been proposed. A simple circuit is constructed to realize the real-time feedback of the phase voltage. Utilizing the actual phase voltage, the compensation time is calculated online. Then the compensation voltage is derived. Simulation and experimental results show the feasibility and effectivity of the proposed method. They also show that the error voltage is decreased and that the waveform is improved.

• 한국지진공학회논문집
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• 제23권4호
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• pp.231-238
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• 2019

A conventional lumped-mass stick model is based on the tributary area method to determine the masses lumped at each node and used in earthquake engineering due to its simplicity in the modeling of structures. However the natural frequencies of the conventional model are normally not identical to those of the actual structure. To solve this problem, recently an updated lumped-mass stick model is developed to provide the natural frequencies identical to actual structure. The present study is to investigate the seismic response accuracy of the updated lumped-mass stick model, comparing with the response results of the shaking table test. For the test, a small size four-story steel frame structure is prepared and tested on shaking table applying five earthquake ground motions. From the comparison with shaking table test results, the updated model shows an average error of 3.65% in the peak displacement response and 9.68% in the peak acceleration response. On the other hand, the conventional model shows an average error of 5.15% and 27.41% for each response.

• 한국광학회지
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• 제32권1호
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• pp.22-28
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• 2021

스마트폰 카메라의 멀티렌즈에서 발생되는 시차현상을 이용하여 실측의 3차원 공간정보를 획득할 수 있는 방법에 대해 연구를 진행하였다. 이를 위한 실험·계측법도 구상해 보았고 관련 방정식도 개발하였다. 본 연구결과를 스마트폰 카메라의 멀티렌즈에 적용하게 되면 건축이나 토목현장에서 스마트폰만으로 한 번에 전체 피사체의 3차원 공간정보를 손쉽게 획득하거나 골프장에서 핀까지의 거리가 얼마나 남았는지 편리하게 알아낼 수 있을 것이다. 멀티렌즈 스마트폰과 연계된 이 기술의 다양한 응용성을 기대해 본다.

• 시스템엔지니어링학술지
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• 제20권spc1호
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• pp.90-96
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• 2024

In this paper, we propose a technique to model high resolution seafloor topography with 1m intervals using actual water depth data near the east coast of the Korea with 1.6km distance intervals. Using a feature point extraction algorithm that harris corner based on deep learning, the location of the center of seafloor mountain was calculated and the surrounding topology was modeled. The modeled high-resolution seafloor topography based on deep learning was verified within 1.1m mean error between the actual warder dept data. And average error that result of calculating based on deep learning was reduced by 54.4% compared to the case that deep learning was not applied. The proposed algorithm is expected to generate high resolution underwater topology for the entire Korean peninsula and be used to establish a path plan for autonomous navigation of underwater vehicle.

• 한국컴퓨터정보학회논문지
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• 제29권7호
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• pp.33-40
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• 2024

가축의 생체중은 건강 및 사육 환경 관리에 중요한 정보이고 이를 통해 최적 사료량이나 출하 시기 등을 결정하게 된다. 일반적으로 가축의 무게를 측정할 때 체중계를 이용하지만, 체중계를 이용한 가축 무게를 측정하는데 상당한 인력과 시간이 필요하고 성장 단계별 측정이 어려워 사료급이량 조절 등의 효과적인 사육 방법이 적용되지 못하는 단점이 있다. 본 연구는 축산 양돈 분야에 영상 및 이미지 데이터를 수집, 분석, 학습, 예측 등을 통해 포유자돈, 이유자돈, 육성돈, 비육돈 구간별 체중 측정에 관한 연구와 함께 정확도를 높이고자 하였다. 이를 위해 파이토치(pytorch), YOLO(you only look once) 5 모델, 사이킷런(scikit learn) 라이브러리를 사용하여 학습시킨 결과, 실제치(actual)와 예측치(prediction) 그래프에서 RMSE(root mean square error) 0.4%와 MAPE(mean absolute percentage error) 0.2%로 유사한 흐름을 확인할 수 있다. 이는 양돈 분야의 포유자돈, 이유자돈, 육성돈, 비육돈 구간에서 활용할 수 있으며 다각도로 학습된 이미지 및 영상 데이터와 실제 측정된 체중 데이터를 바탕으로 지속적인 정확도 향상이 가능하고 향후 영상판독을 통해 돼지의 부유별 생산량에 대한 예측으로 효율적인 사육관리가 가능할 것으로 기대된다.

• 한국정보과학회논문지:시스템및이론
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• 제26권10호
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• pp.1225-1236
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• 1999

기존의 오류 제어 방법들은 실시간 특성과 신축적인 신뢰성을 가지는 멀티미디어 통신 응용의 특징을 충분히 반영하지 못하고 있다. 본 연구는 기존의 재전송을 기반으로 하는 방법에 두 가지 기법을 추가하여 이 문제에 접근하였다. 첫째, 실시간 데이타의 마감 시간을 고려하여 미리 재전송을 실시하는 사전 재전송과 시간적으로 불가능하다고 판단될 때 복구를 포기하는 재전송 포기를 통한 적시 재전송 기법이다. 둘째, 요구되는 신뢰성에 근접하도록 오류가 많이 발생하였을 때만 재전송을 하는 선택적 오류 제어 기법이다. 본 연구는 두 기법을 적용한 오류 제어 프로토콜을 구현하고 네트워크 환경을 바꾸어 가며 성능을 검사하였다. 실험 결과, 제안된 오류 제어 방법은 전체적인 오류 제어 부하는 감소시키면서 오류 복구율을 높인다는 점을 확인하였다.Abstract The current error control schemes do not fit well to the characteristics of multimedia communications: real-time transmission and flexible reliability requirements. This research proposes a new error control scheme, which extends the retransmission-based error control with the following two mechanisms. First, error recovery is performed in two timely fashions: one is retransmission in advance where a retransmission is performed early enough for the deadline if an error is suspected, and the other is retransmission abort where a retransmission is given up if its recovery within the deadline seems to be impossible. Second, error control is selectively performed only when an actual error rate approaches to the threshold on a given reliability requirement. The proposed scheme has been implemented and experimented in various network environments. The performance results show that it has lower control overhead and higher error recovery than the existing schemes.

• 한국경영과학회지
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• 제33권3호
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• pp.59-76
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• 2008

Studies of recommender systems have focused on improving their performance in terms of error rates between the actual and predicted preference values. Also, many studies have been conducted to investigate the relationships between customer information processing and the characteristics of recommender systems via surveys and web-based experiments. However, the actual impact of recommendation on product pages for customer browsing behavior and decision-making in the commercial environment has not, to the best of our knowledge, been investigated with actual clickstream data. The principal objective of this research is to assess the effects of product recommendation on customer behavior in e-Commerce, using actual clickstream data. For this purpose, we utilized an online bookstore's clickstream data prior to and after the web site renovation of the store. We compared the recommendation effects on customer behavior with the data. From these comparisons, we determined that the relevant recommendations in product pages have positive relationships with the acquisition of customer attention and elaboration. Additionally, the placing of recommended items in shopping cart is positively related to suggesting the relevant recommendations. However, the frequencies at which the recommended items were purchased did not differ prior to and after the renovation of the site.

• 한국경영정보학회:학술대회논문집
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• 한국경영정보학회 2008년도 춘계학술대회
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• pp.135-140
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• 2008

Studies of recommender systems have focused on improving their performance in terms of error rates between the actual and predicted preference values. Also, many studies have been conducted to investigate the relationships between customer information processing and the characteristics of recommender systems via surveys and web-based experiments. However, the actual impact of recommendation on product pages for customer browsing behavior and decision-making in the commercial environment has not, to the best of our knowledge, been investigated with actual clickstream data. The principal objective of this research is to assess the effects of product recommendation on customer behavior in e-Commerce, using actual clickstream data. For this purpose, we utilized an online bookstore's clickstream data prior to and after the web site renovation of the store. We compared the recommendation effects on customer behavior with the data. From these comparisons, we determined that the relevant recommendations in product pages have positive relationships with the acquisition of customer attention and elaboration. Additionally, the placing of recommended items in shopping cart is positively related to suggesting the relevant recommendations. However, the frequencies at which the recommended items were purchased did not differ prior to and after the renovation of the site.

• 조명전기설비학회논문지
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• 제25권4호
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• pp.45-56
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• 2011

This paper is proposed artificial neural network(ANN) rotor resistance estimation of induction motor drive controlled by multi-adaptive fuzzy learning controller(AFLC). A simple double layer feedforward ANN trained by the back-propagation technique is employed in the rotor resistance identification. In this estimator, double models of the state variable estimations are used; one provides the actual induction motor output states and the other gives the ANN model output states. The total error between the desired and actual state variables is then back propagated to adjust the weights of the ANN model, so that the output of this model tracks the actual output. When the training is completed, the weights of the ANN correspond to the parameters in the actual motor. The estimation and control performance of ANN and multi-AFLC is evaluated by analysis for various operating conditions. Also, this paper is proposed the analysis results to verify the effectiveness of this controller.