• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.12
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• pp.1890-1897
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• 2022

In this paper, we design a navigation filter for an underwater glider. Underwater gliders are low-cost, reusable, and can be used for a long time. Two types of filters are designed considering characteristics such as small size, low cost, and low power. The navigation filter estimates the reference velocity of the underwater glider's body frame based on the minimum sensor output. The sensor configuration of the first filter consists of an accelerometer, a magnetometer, and a depth sensor. the second filter include extra a gyroscope in the same configuration. The estimated velocity is fused with the attitude, converted into the velocity of the navigation frame and finally the position is estimated. To analyze the performance of the proposed filter, analysis was performed using Monte Carlo numerical analysis method, and the results were analyzed with standard deviation (1σ). Standard deviations of each filter's position error are 334.34m, 125.91m.

• Journal of Sensor Science and Technology
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• v.24 no.4
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• pp.247-251
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• 2015

In this study, electroglottographic spectral tilt (EST) was investigated for characterization of vocal cords vibration. EST was analyzed from the power spectrum of electroglottographic signals by dividing frequency analysis range as full range (0~4 octave), low range (0~2 octave), and high range (2~4 octave). EST of all ranges in female were greater than those in male. In female and male groups, EST of high range was higher than that of low range. This result suggests that EST has at least two components and dividing frequency range in analysis of EST is effective for investigating characteristics of vocal cords vibration.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.203-204
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• 2014

본 연구의 목적은 고연령자를 대상으로 신체 활력 징후의 실시간 정보를 사용자가 스스로 파악 할 수 있는 '자가 헬스케어 제품'을 제안하는 것이다. 신체 활력 징후의 실시간 정보 표출을 위한 제품들의 사례 분석을 통해 기술적 요인과 표현 방법을 추출하고, '장착형 헬스 케어 제품'으로 모듈하기 위해 활용센서와 LED 표출방식에 대한 방법을 도출하였다. Vital Sign(활력 증후) 중 맥박의 실시간 정보는 맥박센서를 통해 추출 되며, 추출 된 정보는 Arduino로 작성 된 알고리즘을 통해 LED 불빛으로 전환 표출된다.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.161-161
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• 2017

• Proceedings of the Korea Contents Association Conference
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• 2010.05a
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• pp.396-398
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• 2010

밀폐된 공간으로 이루어진 작업장은 여러 가지 유해가스가 많이 발생된다. 이로 인해 환기가 불충분한 작업공간에서는 산소결핍 및 유해가스로 인한 건강장해와 인화성 물질에 의한 화재, 폭발 등의 위험이 존재한다. 따라서 유해가스 정보를 작업장 내의 센서를 통해서 실시간으로 모니터링하고, 위험으로부터 작업자의 안전을 보장할 수 있는 모니터링 시스템이 필요하다. 특히, 상황에 맞는 의사결정이 가능하도록 하기 위해 상황인식 시스템의 도입이 필요하다. 이 논문에서는 작업장의 유해가스 정보를 모니터링하기 위한 추론 규칙을 JESS를 기반으로 설계한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.100-100
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• 2004

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.3-16
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• 2008

A Wireless Sensor Network (WSN for short) is a wireless network consisting of distributed small devices which are called sensor nodes or motes. Recently, there has been an extensive research on WSN and also on its security. For secure storage and secure transmission of the sensed information, sensor nodes should be equipped with cryptographic algorithms. Moreover, these algorithms should be efficiently implemented since sensor nodes are highly resource-constrained devices. There are already some existing algorithms applicable to sensor nodes, including public key ciphers such as TinyECC and standard block ciphers such as AES. Stream ciphers, however, are still to be analyzed, since they were only recently standardized in the eSTREAM project. In this paper, we implement over the MicaZ platform nine software-based stream ciphers out of the ten in the second and final phases of the eSTREAM project, and we evaluate their performance. Especially, we apply several optimization techniques to six ciphers including SOSEMANUK, Salsa20 and Rabbit, which have survived after the final phase of the eSTREAM project. We also present the implementation results of hardware-oriented stream ciphers and AES-CFB fur reference. According to our experiment, the encryption speeds of these software-based stream ciphers are in the range of 31-406Kbps, thus most of these ciphers are fairly acceptable fur sensor nodes. In particular, the survivors, SOSEMANUK, Salsa20 and Rabbit, show the throughputs of 406Kbps, 176Kbps and 121Kbps using 70KB, 14KB and 22KB of ROM and 2811B, 799B and 755B of RAM, respectively. From the viewpoint of encryption speed, the performances of these ciphers are much better than that of the software-based AES, which shows the speed of 106Kbps.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.5
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• pp.471-485
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• 2014

The monitoring method of geotechnical structures using acoustic emission(AE) and microseismicity(MS) is to detect the microscopic deformation and fracture behavior in the inner structures by measuring induced acoustics and vibrations. It can identify a pre-indication of failure by taking advantage of the characteristics that the amount and occurrence rates of AE and MS increase rapidly prior to large scale destruction of the target structures. The monitoring system consisting of high-quality sensors, high-speed data acquisition device and the operation program is required for the practical application of this method. Recently, the AE and MS monitoring systems have been localized. In particular, the developed operation software which can analyze and interpret the measured signals was demonstrated through a number of applications to domestic fields. This report introduces the configuration and features of developed monitoring system, then the challenges and future direction of AE monitoring in geotechnical structures are discussed.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.1041-1050
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• 2014

A design and analysis for new foot sensor that measures pressure distribution while walking or running in daily life is introduced. In the process of the sensor design, the shape, mechanism composing of the sensor, and variables that dominate sensor's sensitivity are investigated. Through these variables analysis, an optimal shape and dimension were determined. The effects of variables on sensor's sensitivity and the relationship between each variable are proved by analyses and experiments.

• Journal of Sensor Science and Technology
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• v.23 no.3
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• pp.173-177
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• 2014

A Rhodamine-based fiber-optic sensor has been developed to detect mercury ions in aqueous environments. The fiber-optic sensor was composed of a mercury-sensing thin film, plastic optical fibers, and a spectrometer. The mercury-sensing thin film with the synthesized Rhodamine derivatives was fabricated with Sol-Gel process. A light emitted by a light source is guided by plastic optical fibers into the thin film in an aqueous solution and a reflected light is analyzed with the spectrometer. The experiment exhibits that an absorbance in the thin film is increased as mercury concentration is increased in the solution and the absorbance by mercury is higher than that by other heavy metals. The fiber-optic sensor exhibits high chromogenic phenomenon of mercury ions among various heavy metals and the correlation between absorbance and mercury concentration in the aqueous environments.