• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 추계학술대회
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• pp.54-55
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• 2011

마이크로 스트립 안테나는 최근 소형화, 경량화 및 다층 구조를 통합 집적화 과정을 통하여 통신용 소자로서 그 활용도가 높다. 또한 통신 시스템의 소형화를 통하여 저전력 및 경비 절감이 기대된다. 본 연구에서는 장거리 통신이 가능한 마이크로 스트립 안테나를 설계를 목적으로 하며, 제작된 프로토타입 안테나를 대상으로 네트워크 어낼라이저를 이용하여 그 특성을 분석하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2024년도 춘계학술발표대회
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• pp.764-767
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• 2024

웨어러블 디바이스에서는 사용자의 다양한 메타데이터를 수집할 수 있다. 그러나 이런 개인정보를 함유하고 있는 데이터를 수집하는 것은 사용자에게 개인정보침해 위협을 야기한다. 때문에 본 논문에서는 개인정보보호를 통한 웨어러블 디바이스 데이터활용방안으로 연합학습을 채택하였다. 다만 기존 연합학습에서도 해결해야할 문제점들이 있다. 우리는 그중에서도 데이터이질성(Data Heterogeneity) 문제해결을 위해 군집화(Clustering) 방법을 활용하였다. 또한 기존의 코사인유사도 기반 군집화에서 파라미터중요도가 반영되지 않는다는 문제점을 해결하고자 데이터수 기반 마하라노비스거리(Number of Samples Mahalanobis Distance) 군집화 방법을 제시하였다. 이를 통해 WESAD(Werable Stress Affect Detection)데이터에서 피실험자의 데이터 이질성이 존재하는 상황에서 기존 연합학습보다 학습 안정성 측면에서 좋음을 보여주었다.

• 한국분무공학회지
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• 제19권2호
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• pp.75-81
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• 2014

Swirl flow in the gun type burner has a decisive effect on the stabilization of the flame, improvement of the combustion efficiency, and also a reduction of NOx. This swirl flow is created by the spinner which is inside the airtube that guide the combustion air. Gun type burner has generally the inner devices composed nozzle adapter, spark gap ignitor, and spinner. These inner components change the air flow behavior passing through air tube. Meanwhile, turbulent characteristics of this air flow are important to understand the combustion phenomena in the gun type burner, because the mixture of fuel and air are depended on. However, nearly all of the studies have been analyzed the turbulent flow of simplified combustion formation without the inner devices. So, this study conducted the measurement using by hot-wire anemometer and analyzed turbulent flow characteristics of the swirl flow discharged from the air tube with inner devices. Turbulence characteristics come up in this study were turbulence intensity, kinetic energy and shear stress of the air flow with the change of the distance of axial direction from the exit of the air tube.

• 한국도로학회논문집
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• 제20권1호
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• pp.137-146
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• 2018

PURPOSES : This study aims to analyze how the installation of advanced warning devices affects individual drivers' driving behaviors with operating record data collected from 100 vehicles. METHODS : With collected data, the changes in individual drivers' driving behaviors, such as Forward Collision Warning (FCW) and Lane Departure Warning (LDW), were investigated with respect to the cumulative distance traveled and driving time. For the analysis, operating record data collected from 100 vehicles for seven months were used. RESULTS : The results showed that individual drivers' driving behaviors could be categorized into six different types. In addition, most of the drivers showed unstable warning patterns in the initial stage after installation of an advanced warning device. Approximately 40% of vehicles equipped with advanced warning systems were found to have positive effects, indicating that the frequencies of both FCW and LDW had been continuously decreasing after installation of the system. CONCLUSIONS : The warning device might be helpful for making drivers' driving behaviors safer. Driving behaviors during the initial stage of the system installation, which might be regarded as an adaptation phase, were found to be very unstable compared with normal situations, indicating that adequate education and training should be provided to all the drivers to prevent operator disruption at the initial installation of the system.

• 인간식물환경학회지
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• 제22권2호
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• pp.219-229
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• 2019

This study was carried out to verify the accuracy of fitness tracking devices in monitoring heart rate and energy consumption and to contribute to the development of a forest exercise program that can recommend the intensity and amount of forest exercises based on personal health-related data and provide monitoring and feedback on forest exercises. Among several commercially available wearable devices, Fitbit was selected for the research, as it provides Open API and data collected by Fitbit can be utilized by third parties to develop programs. Fitbit provides users with various information collected during forest exercises including exercise time and distance, heart rate, energy consumption, as well as the altitude and slope of forests collected by GPS. However, in order to verify the usability of the heart rate and energy consumption data collected by Fitbit in forest, the accuracy of heart rate and energy consumption were verified by comparing the data collected by Fitbit and reference. In this study, 13 middle-aged women were participated, and it was found that the heart rate measured by Fitbit showed a very low error rate and high correlation with that measured by the reference. The energy consumption measured by Fitbit was not significantly different from that measured in the reference, but the error rate was slightly higher. However, there was high correlation between the results measured by Fibit and the reference, therefore, it can be concluded that Fitbit can be utilized in developing actual forest exercise programs.

• ETRI Journal
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• 제32권5호
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• pp.795-800
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• 2010

Embedding a large vocabulary speech recognition system in mobile devices requires a reduced acoustic model obtained by eliminating redundant model parameters. In conventional optimization methods based on the minimum description length (MDL) criterion, a binary Gaussian tree is built at each state of a hidden Markov model by iteratively finding and merging similar mixture components. An optimal subset of the tree nodes is then selected to generate a downsized acoustic model. To obtain a better binary Gaussian tree by improving the process of finding the most similar Gaussian components, this paper proposes a new distance measure that exploits the difference in likelihood values for cases before and after two components are combined. The mixture weight of Gaussian components is also introduced in the component merging step. Experimental results show that the proposed method outperforms MDL-based optimization using either a Kullback-Leibler (KL) divergence or weighted KL divergence measure. The proposed method could also reduce the acoustic model size by 50% with less than a 1.5% increase in error rate compared to a baseline system.

• 정보처리학회논문지C
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• 제11C권3호
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• pp.401-408
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• 2004

트리 구조를 기반으로 하는 블루투스 스캐터넷은 적은 링크 수와 간단한 라우팅 방법 등 여러 가지 장점을 가지고 있다. 본 논문은 블루투스 규격상의 제약조건을 만족시키면서 노드 간 평균거리가 가장 짧은 트리형태에 가까운 스캐터넷을 형성하는 알고리즘을 제시한다. 그리고 제시한 방법이 기존의 방법보다 지연시간을 더 초래하지 않고도 장치 간 평균 홉 수를 감소시킬 수 있음을 시뮬레이션을 통하여 보인다.

• 전자통신동향분석
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• 제39권1호
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• pp.48-61
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• 2024

The integration of high-capacity terrestrial networks with non-terrestrial communication using satellites has become essential to support seamless low-latency services based on artificial intelligence and big data. Tunable light sources have been instrumental in resolving the complexity of channel management in wavelength division multiplexing (WDM) systems, contributing to increased network flexibility and serving as optical sources for long-distance coherent systems. Recently, these light sources have been applied to beam-steering devices in laser communication and sensing applications across ground, aerial, and satellite transport. We examine the utilization and requirements of tunable lasers in WDM networks and describe the relevant development status. In addition, performance requirements and development directions for tunable lasers used in optical interference systems and beam-steering devices are reviewed.

• 한국IT서비스학회지
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• 제19권3호
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• pp.139-149
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• 2020

There are now many different commercial weather sensors suitable for smart farms, and various smart farm devices are being developed and distributed by companies participating in the government-led smart farm expansion project. However, most do not comply with standard specifications and are therefore limited to use in smart farms. This paper proposed the connecting structure of operating non-standard node devices in smart farms following standard specifications supporting smart greenhouse. This connecting structure was proposed as both a virtual node module method and a virtual node wrapper method. In addition, the SoftFarm2.0 system was experimentally operated to analyze the performance of the implementation of the two methods. SoftFarm2.0 system complies with the standard specifications and supports non-standard smart farm devices. According to the analysis results, both methods do not significantly affect performance in the operation of the smart farm. Therefore, it would be good to select and implement the method suitable for each non-standard smart farm device considering environmental constraints such as power, space, distance of communication between the gateway and the node of the smart farm, and software openness. This will greatly contribute to the spread of smart farms by maximizing deployment cost savings.

• Current Optics and Photonics
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• 제2권4호
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• pp.348-355
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• 2018

How to measure the creepage distance of an insulator quickly and accurately is a problem for the power industry at present, and the noticeable concern is that the high voltage insulation equipment cannot be measured online in the charged state. In view of this situation, we develop an on-line measurement system of creepage distance for high voltage insulators based on binocular stereo vision. We have proposed a method of generating linear structured light using a conical off-axis mirror. The feasibility and effect of two ways to solve the interference problem of strong sunlight have been discussed, one way is to use bandpass filters to enhance the contrast ratio of linear structured light in the images, and the other way is to process the images with adaptive threshold segmentation and feature point extraction. After the system is calibrated, we tested the measurement error of the on-line measurement system with a composite insulator sample. Experimental results show that the maximum relative error is 1.45% and the average relative error is 0.69%, which satisfies the task requirement of not more than 5% of the maximum relative error.