• The Journal of the Acoustical Society of Korea
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• v.38 no.2
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• pp.193-199
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• 2019

In this paper, the results of underwater vibration experiment are analyzed to verify platform vibration-induced noise isolation characteristics of a hull-mounted acoustic sensor. The experimental condition causing platform vibration-induced noise is generated using the mock-up hull, where the acoustic sensor is installed, with shaker in an acoustic water tank. The performance indices of ATF (Acceleration Transfer Function), AVS (Acceleration Voltage Sensitivity), and IL (Insertion Loss) for the acoustic sensor are calculated from the output of the standard accelerometers, which are installed on the mock-up hull and the acoustic sensor, and the output signal of the acoustic sensor. The frequency-dependent noise isolation characteristics of the acoustic sensor are analyzed based on the calculated performance indices and an effectiveness of the experiment is examined.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.60-65
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• 2017

This paper describes the low noise and low power IC using the opamp sharing technique for the capacitive micro-sensor sensing platform. The proposed IC reduces noise using correlated double sampling (CDS) and reduces power consumption using the opamp sharing technique. The IC is designed to be fully programmable, and can be digitally controlled by serial peripheral interface (SPI). The power consumption and the integrated input referred noise are 1.02 mW from a 3.3 V supply voltage and $0.164aF_{RMS}$ with a bandwidth of 400 Hz. The capacitive sensitivity, the input-output linearity and the figure of merits (FoM) are 2.5 mV/fF, 2.46 %FSO, and 8.4, respectively.

• Journal of Information Processing Systems
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• v.11 no.2
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• pp.205-228
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• 2015

In this paper, we present a virtual laboratory platform (VLP) baptized Mercury allowing students to make practical work (PW) on different aspects of mobile wireless sensor networks (WSNs). Our choice of WSNs is motivated mainly by the use of real experiments needed in most courses about WSNs. These experiments require an expensive investment and a lot of nodes in the classroom. To illustrate our study, we propose a course related to energy efficient and safe weighted clustering algorithm. This algorithm which is coupled with suitable routing protocols, aims to maintain stable clustering structure, to prevent most routing attacks on sensor networks, to guaranty energy saving in order to extend the lifespan of the network. It also offers a better performance in terms of the number of re-affiliations. The platform presented here aims at showing the feasibility, the flexibility and the reduced cost of such a realization. We demonstrate the performance of the proposed algorithms that contribute to the familiarization of the learners in the field of WSNs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.1015-1022
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• 2010

USN(Ubiquitous Sensor Network) environment that provides the service measured from sensors in real-time the information is delivered to application service. However, domestic service, application service provider environment between providers and users, most of the research are on the service platform architecture, and process the information detected by sensors between the providers of standard services platform architecture, which is a very weak level. In this paper, we proposed new service architecture though analysis of the OGC SWE(Sensor Web Enablement) with standards and research analysis of domestic standards. And we designed and implemented to each component of provider side.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.155-162
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• 2016

TASS(Towed Array Sonar System) is a sonar system which tows the sensor array behind a platform. Array shape is generally assumed to be a straight line. But the array shape is often distorted by oceanic current or platform maneuvering which causes the performance loss of signal processing method like beamforming. So array shape estimation methods are needed. Typically the method based on Kalman filter using heading sensor is used. In practice, the measurement is corrupted by biases which are caused by rotation of the tow cable, varying magnetic fields and slowly varying stresses in the mechanical construction. Although they can't be calibrated but can be estimated. In this paper, we suggest the array shape estimation method based on Kalman filter compensating the sensor biases.

• The Journal of Information Technology
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• v.12 no.3
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• pp.1-6
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• 2009

This paper has focused on the development of an educational sensor network (ESN) based on wireless sensor networks(WSN) and pervasive monitoring systems for students' activity during scientific experiments. A number of WSN systems have been proposed with integrated wireless transmission, mounted sensor boards and local processing. However, there is no trail to employ WSN on the educational field. In this paper, to facilitate research and development using wireless sensor network and multi-sensor data fusion, the educational sensor network (ESN) hardware development platform is presented. The ESN project is conducted over one semester time period (Spring Semesters). It involves approximately twenty middle school students who enrolled a gifted program in Kongju National University. Though under prepared, these students are in general highly motivated to learning specially when presented with the ESN project. An ESN project such as this is expected to provide an excellent means for teaching and learning scientific and mathematical principles.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.525-543
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• 2010

Testing and validation processes are critical tasks in developing a new hardware platform based on a new technology. This paper describes a series of experiments to evaluate the performance of a newly developed MEMS-based wireless sensor node as part of a wireless sensor network (WSN). The sensor node consists of a sensor board with four accelerometers, a thermometer and filtering and digitization units, and a MICAz mote for control, local computation and communication. The experiments include calibration and linearity tests for all sensor channels on the sensor boards, dynamic range tests to evaluate their performance when subjected to varying excitation, noise characteristic tests to quantify the noise floor of the sensor board, and temperature tests to study the behavior of the sensors under changing temperature profiles. The paper also describes a large-scale deployment of the WSN on a long-span suspension bridge, which lasted over three months and continuously collected ambient vibration and temperature data on the bridge. Statistical modal properties of a bridge tower are presented and compared with similar estimates from a previous deployment of sensors on the bridge and finite element models.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.654-659
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• 2009

As web based software has developed recently, service via web has increased gradually. For this, many research organizations and reports call web is the platform of software. While web based technologies have developed, middleware of WSN and its application service has been developed from desktop based operation system. So WSN's technology reached uppermost limit of desktop application. There's difficulty in integrating, distributing and maintaining & repairing for WSN due to a tightly-coupled structure which's related closely to the hardware of sensor nod. Unlike this, web has a loosely-coupled structure and an opened system, so web service or Rich internet application (RIA) is helpful to solve the above limits. Especially, RIA is web application but can be the platform of WSN' application because it gives us various methods to communicate with user interface similar to desktop application. In this study, I suggest Message System for WSN Using RIA, expanding WSN's interconnectedness and accessibility to internet.

• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.56-61
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• 2015

In this paper, the 3D positioning of IoT sensors with the Unity engine of android platform based home-hub was proposde for IoT(Internet of Things) users. Especially, the monitoring of IoT sensor and battery status was designed with the clustering of IoT sensor's position. The 3D positioning of RSSI(received signal strength indicator) and angle for new IoT sensor according to clustering method was described with the cooperation of beacon and received arrival signal time. This unity engine based smart hub platform can monitor the working situation of IoT sensors, and apply 3D video with texture for the life-cycling of many IoT sensors simultaneously. rs was described with RSSI(received signal strength indicator) and received angle.

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.83-91
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• 2001

This paper proposes the Focused beamforming to estimate the location of target residing near to the observation platform in the underwater environment. The Focused beamforming technique provides the location of target by the coherent summation of a series of incident spherical waveforms considering distinct propagation delay times at the sensor array. But due to the movement of the observation platform and the variation of the underwater environment, the shape of the sensor array is no longer to be linear but it becomes distorted as the platform moves. Thus the Focused beamforming should be peformed regarding to the geometric shape variation at each time. To estimate the target location, the artificial image plane comprised of cells is constructed, and the delays are calculated from each cell where the target could be proximity to sensors for the coherent summation. After the coherent combining, the beam pattern can be obtained through the Focused beamforming on the image plane. Futhermore to compensate the variation of the shape of the sensor array, the paper utilizes the Nth-order polynomial approximation to estimate the shape of the sensor array obeying the water pulley modeling. Simulation results show the performance of the Focused beamforming for different frequency bands of the radiated signal.