• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권5호
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• pp.1984-2002
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• 2020

With the appearance of wireless spectrum crisis in traditional cellular network, device-to-device (D2D) communication has been regarded as a promising solution to ease heavy traffic burden by enabling precise content delivery among mobile users. However, due to the channel sharing, the interference between D2D and cellular users can affect the transmission rate and narrow the throughput in the network. In this paper, we firstly present a weighted interference minimization cluster formation model involving both social attribute and physical closeness. The weighted-interference, which is evaluated under the susceptible-infected(SI) model, is utilized to gather user in social and physical proximity. Then, we address the cluster formation problem via spectrum clustering with iterative operation. Finally, we propose the stable matching theory algorithm in order to maximize rate oriented to accomplish the one-to-one resource allocation. Numerical results show that our proposed scheme acquires quite well clustering effect and increases the accumulative transmission rate compared with the other two advanced schemes.

• 한국안전학회지
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• 제30권6호
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• pp.117-121
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• 2015

$O_2$-deficiency related accidents occur every year and the most effective way to prevent them is to measure $O_2$ concentration in air with a properly-calibrated $O_2$ monitoring device before entering low-$O_2$ areas. An electro-chemical sensor, Texas Instrument gas platform, and iPhone are used to construct a smartphone-based $O_2$ monitoring device. The smartphone based $O_2$ measuring approach offers advantages of small size, accessibility, internet-connectivity, and programmability in comparison to conventional $O_2$ measuring devices. Multiple gas sensors can be conveniently interfaced to single smartphone, allowing for creating a network of gas sensors distributed across workplaces and remote monitoring via existing mobile communication network. To check proper function of the $O_2$ monitoring device the sensor was exposed to shallow and deep human breaths. The readings decreased immediately after being exposed to exhalation and recovered during inhalation to a calibrated level of 20.9%. When readings decreased below a preset warning value of 19.5%, a low $O_2$ warning was successfully activated on the smartphone.

• 전기학회논문지
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• 제65권3호
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• pp.487-492
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• 2016

In this paper, a device for analyzing the pressure distribution during walking was produced by using the pressure sensor on the heel. This device was limited to a frequency band by using the 1st low-pass filter. And an algorithm to analyze the value of the quantity to pressure using a analog to digital converter. It is used by using the threshold voltage of pressure sensor, it is suggested the algorithm. The algorithm is detected the peak which is exceeded the threshold voltage. and thus in accordance, it is detected the number of steps. And the calorie consumption were detected by using it. Also it used an MCU and Bluetooth. And by confirming the data at the LCD of the other MCU, it was to reduce the size of the device. According to this algorithm, it has the advantage that there is no restriction on the activity than when using an imaging device and it is inexpensive than other sensors such as an acceleration sensor or a gyro and it is easy to handle.

• 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.

• 센서학회지
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• 제27권6호
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• pp.392-396
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• 2018

Structural color has many advantages over pigment based color. In recent years, researches are being conducted to apply these advantages to applications such as wearable devices. In this study, strain sensor, a kind of wearable device, was developed using structural color. The use of structural color has the advantage of not using energy and complex measuring equipment to measure strain rate. Wrinkle structure was fabricated on the surface of Poly-dimethylsiloxane (PDMS) and used it as a sensor which color changes according to the applied strain. In addition, a transmittance-changing sensor was developed and fabricated by synthesizing additional glass nanoparticles. Furthermore, a strain sensor was developed that is largely transparent at the target strain and opaque otherwise.

• 한국정밀공학회지
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• 제12권8호
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• pp.73-85
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• 1995

The sensor system to measure the distance precisely from the center of the sensor system to the obstacle is needed to recognize the surrounding environments, and the sensor system is to be calibrated thoroughly to get the range information exactly. This study covers the calibration of the active range sensor which consists of camera and laser slit emitting device, and provides the equations to get the 3D range data. This can be possible by obtaining the extrinsic parameters of laser slit emitting device through image processing the slits measured during the constant distance intervals and the intrinsic parameters from the calibration of camera. The 3D range data equation derived from the simple geometric assumptions is proved to be applicable to the general cases using the calibration parameters. Also the exact 3D range data were obtained to the object from the real experiment.

• 한국정보통신학회논문지
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• 제20권6호
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• pp.1136-1141
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• 2016

사물인터넷 기술은 지능형 정보처리를 필요로 하는 여러 융합 서비스의 주요 핵심 기술로 이용되고 있으며 그 중요성 또한 크게 부각되고 있다. 그리고 사물인터넷 인터랙션 디바이스를 통한 내부 네트워크 구축은 사물인터넷 디바이스를 효율적으로 연결 및 관리하며, 개방형 플랫폼과의 연동을 통해 다양한 서비스를 제공할 수 있게 한다. 특히, 저 전력 블루투스 기반 무선통신 장치인 비콘이 사물인터넷의 주요 핵심 기술로 주목받고 있다. 비콘 기술은 다양한 산업 분야에서 널리 활용되고 있으며, 최근에는 기본 기능을 넘어 특정 환경과 조건에서 사용하고자 하는 수요가 많이 늘어나고 있다. 본 논문에서는 이러한 비콘 기술과 관련하여 가속도 센서와 홀 센서를 활용한 비콘 디바이스를 제안한다. 제안한 비콘 디바이스는 센서를 통한 이동 감지를 통해 특정 상황에서의 제어가 가능하다. 아울러, 탈부착 형태의 편리한 설치, 센서를 연동한 최적화 관리 등 다양한 공장 환경에 적용이 가능할 수 있을 것으로 기대한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권6호
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• pp.597-611
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• 2009

With the advent of ubiquitous computing society, many advanced technologies have enabled wireless sensor networks which consist of small sensor nodes. However, the sensor nodes have limited computing resources such as small size memory, low battery life, short transmission range, and low computational capabilities. Thus, decreasing energy consumption is one of the most significant issues in wireless sensor networks. In addition, numerous applications for wireless sensor networks are recently spreading to various fields (health-care, surveillance, location tracking, unmanned monitoring, nuclear reactor control, crop harvesting control, u-city, building automation etc.). For many of them, supporting security functionalities is an indispensable feature. Especially in case wireless sensor networks should provide a sufficient variety of security functions, sensor nodes are required to have more powerful performance and more energy demanding features. In other words, simultaneously providing security features and saving energy faces a trade-off problem. This paper presents a novel energy-efficient security architecture in an IEEE 802.15.4-based wireless sensor network called the Hybrid Adaptive Security (HAS) framework in order to resolve the trade off issue between security and energy. Moreover, we present a performance analysis based on the experimental results and a real implementation model in order to verify the proposed approach.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제5권2호
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• pp.27-32
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• 2016

개인의 건강 및 상태 정보를 모니터링하기 위한 다양한 센서 기기들이 개발되고 있으며, 스마트폰 상에서 동작하는 응용과 연동을 통해 개인화된 정보를 시각화하여 보여주는 서비스들이 등장하고 있다. 이러한 응용들은 유사한 정보를 사용자에게 제공하면서도 표준화되지 않은 패킷 구조로 인해 센서 기기마다 별도의 응용을 설치해야 하는 문제가 있다. 본 논문에서는 비표준화된 개인용 센서 기기들이 스마트폰과 동적으로 연동될 수 있는 센서 기기 식별 기법을 제안한다. 제안 기법은 센서 기기에 대한 패킷 정보를 서버에 저장하기 때문에 사용하는 센서가 변동되더라도 스마트폰 상에서 동작하는 클라이언트의 변경 없이 응용을 동작할 수 있는 장점이 있다.

• 센서학회지
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• 제4권1호
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• pp.15-20
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• 1995

본 논문은 시변전장을 측정할 수 있는 평판형 센서에 대하여 기술하였다. 광대역의 전장측정계를 구현하기 한 평판형 센서가 제안되었다. 측정계의 이론적인 원리와 설계방법에 대하여 제시하였으며, 교정실험 및 적용실험을 수행하였다. 교정실험을 통하여 전장측정계의 주파수대역과 감도는 $160\;[Hz]\;{\sim}\;25\;[MHz]$, 1.2 [mV/V/m] 이었다. 적용실험으로 고전압 실험실에서 임펄스전압과 진동성 과도전압에 의해 발생되는 전장을 제안된 측정장치로 측정하였으며, 측정결과는 우수하였다.