• Journal of the Institute of Convergence Signal Processing
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• v.14 no.1
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• pp.45-50
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• 2013

Sensors have limited resources in sensor networks, so efficient use of energy is important. Representative clustering methods, LEACH, LEACHC, TEEN generally use direct transmission methods from cluster headers to a sink node to pass collected data. If clusters are located at a long distance from the sink node, the cluster headers exhaust a lot of energy in order to transfer the data. As a consequence, the life of sensors is shorten and re-clustering is needed. In the process of clustering, sensor nodes consume some energy and the energy depletion of the cluster headers meet another energy exhaustion. A method of transferring data from cluster headers to the sink using neighbor clusters is needed for saving energy. In this paper, we propose a novel routing method using a multi-hop transmission method in cluster sensor networks. This method uses the topology matrix which presents cluster topology. One-hop routing and two-hop routing are proposed in order to increase the energy efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.578-583
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• 2017

This paper presents a 3D touch pad technology that uses force touch sensors as a next-generation method for mobile applications. 3D touch technology requires detecting the location and pressure of touches simultaneously, as well as multi-touch function. We used metal foil strain gauges for the touch recognition sensor and detected the weak touch signals using Wheatstone bridge circuit at each strain gauge sensor. We also developed a touch recognition system that amplifies touch signals, converts them to digital data through a microprocessor, and displays the data on a screen. In software, we designed a touch recognition algorithm with C code, which is capable of recognizing two-point touch and differentiating touch pressures. We carried out a successful experiment to display two touch signals on a screen with different forces and locations.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.143-148
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• 2019

In modern society, developing and utilizing safety service and system environments is a very important and great interest. In particular, the provision of safety services to socially vulnerable groups such as children, the elderly, women, the disabled and foreigners has become a social issue. However, since most safety services and systems are applied to the general public, it is necessary to develop systems for socially vulnerable groups. Therefore, in this paper, we developed a system module that processes and transmits data to recognize the situation in real time and respond quickly. To this end, various sensors for real-time situation recognition were designed as integrated modules, and a safety system module was developed to analyze the collected data and transmit the processing results.

• Journal of information and communication convergence engineering
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• v.8 no.2
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• pp.223-227
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• 2010

In this paper, we present a QoS-aware MAC protocol (QA-MAC) for cluster based wireless sensor networks (WSNs). QA-MAC is a TDMA-based scheduling protocol that minimizes the energy consumption in multi-hop WSNs and provides Quality of Service (QoS). A dynamic scheduling algorithm according to the number of member nodes, node traffics, and traffic priorities is suggested. The selected cluster head allocates time slots for all member nodes in the first TDMA schedule period of each round. During the second schedule period in each round, the cluster head makes a schedule for all data transmission. The proposed QA-MAC (QoS-Aware MAC) could save energy, reduce transmission delay, and support QoS.

• Smart Structures and Systems
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• v.24 no.6
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• pp.693-707
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• 2019

This paper proposes an integrated safety assessment method that can take multiple sources data into consideration based on a data fusion approach. Data cleaning using the Kalman filter method (KF) was conducted first for monitoring data from each sensor. The inclination data from the four tilt sensors of the same monitoring section have been associated to synchronize in time. Secondly, the finite element method (FEM) model was established to physically correlate the external forces with various structural responses of the shield tunnel, including the measured inclination. Response surface method (RSM) was adopted to express the relationship between external forces and the structural responses. Then, the external forces were updated based on the in situ monitoring data from tilt sensors using the extended Kalman filter method (EKF). Finally, mechanics parameters of the tunnel lining were estimated based on the updated data to make an integrated safety assessment. An application example of the proposed method was presented for an urban tunnel during a nearby deep excavation with multiple source monitoring plans. The change of tunnel convergence, bolt stress and segment internal forces can also be calculated based on the real time deformation monitoring of the shield tunnel. The proposed method was verified by predicting the data using the other three sensors in the same section. The correlation among different monitoring data has been discussed before the conclusion was drawn.

• Journal of information and communication convergence engineering
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• v.7 no.2
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• pp.176-181
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• 2009

This study is part of a project to develop and improve mooring systems for oceanographic use that include an electro-optical sensor, 1MHz Nortek Aquadopp Doppler Profiler and AIRMAR multipurpose Sensor. The adaption of Doppler current profilers to measure directional wave spectra has provided a new instrumentation approach to coastal and nearshore oceanographic studies. The HEIOB is developed are light weight and of a compact design, and can be easily installed in marine environment. Since there are no base station and gateways in marine environments, we selected CDMA and Orbcomm to send the data information. Therefore, the data can be sent by either e-mail service or Short Message Service (SMS). This paper will present some of scientific sensor results regarding real-time oceanographic and meteorological parameters such as wind spend, wind direction, wave direction, and etc. The modeling and test results highlight the engineering challenges associated with designing these systems for long lifetimes. It can also be used in future application to build wave observation buoy network in real-time using multiple ubiquitous buoys that share wave data and allow analysis of multipoint, multi-layer wave profiler.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.1
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• pp.20-29
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• 2021

This study developed a smartwatch and a wind speed system in accordance with the necessity of a device that provides the information required in marine leisure. Based on a marine leisure smartwatch with a multi-sensor, a gyro box, and a wind speed system, external data such as GPS, motion, humidity, temperature, air pressure, and heart rate can be collected. In addition, the collected external environment data can be managed through an application on a smartphone, which is an Android-based mobile device. The developed smartwatch and wind speed system are expected to contribute to increasing accessibility and revitalization of the marine leisure industry. In addition, in terms of safety and education, the need for a device that provides marine information is large, so it is expected to increase the possibility of entering the high value-added market and improve the product localization rate.

• The Journal of the Convergence on Culture Technology
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• v.4 no.4
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• pp.419-427
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• 2018

This paper designs and develops auto-tuning temperature controller with multi-channel, which controller with multi-channel could control a number of control system simultaneously. This controller has multi-channel input and output. And a number of control algorithms run in this controller simultaneously and independently. Firstly we present design method of controller with multi-channel. Secondly we design electrical circuit of sensor input, controller output and power control for temperature control board. And finally we design data protocol for serial communication to monitor control state and present verification of temperature controller with muiti-channel through field experiment.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.135-138
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• 2020

무선 센서 네트워크에서 모바일 싱크의 도입은 기존의 고정된 위치의 싱크를 사용하는 WSN에서 발생하는, 싱크 주변 노드들과 외곽 노드들 간의 에너지 불균형 문제(에너지 핫스팟 문제)를 어느 정도 해결할 수 있게 하였다. 그러나 모바일 싱크의 에너지 제약으로 인해 싱크가 모든 노드를 방문하여 데이터를 수집할 수 없기 때문에, 앵커(또는 헤드)라고 불리는 특정 노드에서 데이터를 모으고, 모바일 싱크는 이러한 앵커 노드들만을 방문하는 방법이 널리 사용되고 있다. 최근 연구에서는 모바일 싱크가 보다 효율적으로 에너지 불균형 문제를 해결하기 위하여 모바일 싱크 이동 경로 및 앵커 노드 선정 최적화 방법이 활발히 연구되고 있다. 본 연구에서는 태양 에너지 기반 센서 네트워크를 위한 영역 기반 앵커 선정 기법 및 모바일 싱크 이동 경로 선택 기법을 제안한다. 제안 기법은 각 노드가 수집하는 태양 에너지의 활용을 최대화하고, 에너지 핫스팟 문제를 완화하기 위해 두 개의 라인(영역)을 설정하고 이 라인을 따라 앵커 노드가 선정된다. 모바일 싱크는 데이터 수집을 위해 이 두 라인을 왕복 이동 경로로 택하여 라인 내의 앵커 노드를 방문한다. 실험을 통해 제안 기법이 기존 기법보다 에너지 불균형 문제가 완화되어 노드의 정전 시간이 줄어들고, 이에 따라 모바일 싱크에서 수집되는 데이터의 양이 증가하는 것을 확인하였다.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.884-887
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• 2023

Recently, research has been actively conducted to overcome the limitations of high-priced single sensors and reduce costs through the convergence of low-cost multi-variable sensors. This paper estimates state variables through asynchronous Kalman filters constructed using CVXPY and uses Cvxpylayers to compare and learn state variables estimated from CVXPY with true value data to estimate filter parameters of low-cost sensors fusion.