• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1384-1387
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• 2015

고령화 사회로 진입하면서 노인들은 노화과정에 의한 보행능력의 감소 및 근력 약화와 같은 신체적 변화로 인해 잦은 낙상을 경험한다. 이에 따라 낙상 사고를 감지하는 연구가 활발히 진행되고 있다. 낙상은 사전 예방도 중요하지만 사고 발생 후의 신속한 대처도 중요하다. 낙상을 감지하고 의료진에게 즉시 낙상정보를 제공하여 후속적 조치를 취하는 것은 사고 후 대처의 핵심이다. 본 논문에서는 스마트폰 환경에서 사용자의 낙상 후 방향을 판별하기 위해 두 가지 센서 데이터의 특정 값들을 추출하였으며, 이에 5 가지 기계학습 알고리즘을 적용하였다. 사용자는 스마트폰을 착용한 상태로 전후좌우 4 방향 낙상 실험을 진행하며 스마트폰 내에 내장된 3 축 가속도 센서와 3 축 자이로 센서값을 측정한다. 피험자 11 명을 대상으로 낙상 실험 결과, 5 가지의 분류기 중 k-NN에서 98.6%의 인식률을 나타내었다. 뽑아낸 특징 값과 분류 알고리즘은 낙상의 방향 검출에 유용한 것으로 판단된다.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2218-2220
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• 2004

조종사 없이 사전에 입력된 프로그램 또는 인공지능에 의해 기체 스스로 판단하여 자율비행하는 비행체를 무인 항공기라 한다.[6] 이러한 비행을 위해서는 기체의 위치, 자세, 속도 등의 정보가 필요하다. 본 논문에서는 3축 가속도센서 1개 및 1축 자이로센서 3개를 서로 수직으로 구성하는 관성항법 시스템에 자기콤파스, 고도센서, GPS등의 비관성센서를 추가로 구성하여 시스템을 설계하였으며 칼만필터를 이용하여 시스템의 오차를 추정하고 이를 되먹임 시킴으로써 오차를 정정한다.

• The Journal of the Korea Contents Association
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• v.6 no.12
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• pp.96-104
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• 2006

In this study, data transmission ratio and power consumption issues of Zigbee based sensor module and personal digital assistant(PDA) were addressed to develop ECG telemetry device. PDA processes the data transmitted through serial port using non-blocking method. The transmission rate was dependent on the packet structure. It was 300 ECG samples/sec, when each packet was composed of 2 ECG data and 3-axial acceleration vector. Using two AAA batteries in series, operating time of the wireless sensor module was above 28 hours in average. Power consumption of PDA was dependent on screen ON/OFF condition and serial port usage. In this application, operating time of PDA was 5 hours in average. In conclusion, there was no problem in the power consumption of wireless sensor module and transmission rate, when the developed device was used as 24 hour Holter device. But, PDA has the problem of power consumption, which should be solved.

• Current Research on Agriculture and Life Sciences
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• v.32 no.2
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• pp.79-84
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• 2014

The precision aerial application of agricultural unmanned helicopters has become a new paradigm for small farms with orchards, paddy, and upland fields. The needs of agricultural applications require easy and affordable control systems. Recent developments of MEMS technology based on inertial sensors and high speed DSP have enabled the fabrication of low-cost attitude system. Therefore, this study evaluates inertial MEMS sensors for estimating the attitude of an agricultural unmanned helicopter. The accuracies and errors of gyro and acceleration sensors were verified using a pendulum system. The true motion values were calculated using a theoretical estimation and absolute encoder measurement of the pendulum, and then the sensor output was compared with reference values. When comparing the sensor measurements and true values, the errors were determined to be 4.32~5.72%, 3.53~6.74%, and 3.91~4.16% for the gyro rate and x-, z- accelerations, respectively. Thus, the measurement results confirmed that the inertial sensors are effective for establishing an attitude and heading reference system (AHRES). The sensors would be constructed in gimbals for the estimating and proving attitude measurements in the following paper.

• Journal of the Korea Convergence Society
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• v.10 no.6
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• pp.179-184
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• 2019

Recently, various problems have arisen due to the popularization and aging of urban railway transit, which is the key transportation of large cities. In this study, the vibrational accelerations for the Daegu Metropolitan City Urban Railway(Line 1) were measured and evaluated using the smartphone built-in acceleration sensor and the approved application. For this purpose, the three axes running accelerations were measured according to the domestic standard (KS R 9160), and the acceleration data along the 32 stations (3 directions) were analyzed and compared. In addition, the increasing of acceleration values caused by the change of vibrational environment was monitored along the main stations between the time in 1997 and 2017. It was found that there are considerable increase of lateral and vertical directional accelerations due to the aging of railway facility environment for the last 20 years. The results of this study have valuable means for evaluating the ride quality of urban railway and the vibration influence on surrounding structures.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.516-518
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• 2022

In this paper, we introduce a dependence of number of nodes of hidden-layer in fall detection system using Long Short-Term Memory that can detect falls. Its training is carried out using the parameter theta(θ), which indicates the angle formed by the x, y, and z-axis data for the direction of gravity using a 3-axis acceleration sensor. In its learning, validation is performed and divided into training data and test data in a ratio of 8:2, and training is performed by changing the number of nodes in the hidden layer to increase efficiency. When the number of nodes is 128, the best accuracy is shown with Accuracy = 99.82%, Specificity = 99.58%, and Sensitivity = 100%.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.3
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• pp.216-220
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• 2009

In this paper we propose a motion recognition method for handheld controller 3-D acceleration signals, generated by 3 axis accelerometer in the controller, are transmitted to the computer by Bluetooth communication. We extract motion segments from continuous acceleration signals and apply to each motion model, which is trained in training phase. Hidden Markov Model was used to model each motion. We applied proposed method to three motion sets, the recognition result was good enough to practical use.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.184-188
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• 2008

Performance degradation of concrete structures is generally caused by structural deteriorations, such as cracks. It may result in serious defects of concrete structures. Methods of damage detection are used a visual angle of human or non-destructive test, and they are using various sensors. Problems of crack damage detection are occurred to directions of cracks by using 1 axial type of accelerometer in concrete element. In addition, these sensors are not used to occurring fire in RC building. Thermocouple sensors are able to using measurement of temperature in fire, and then deformations of main element and structures are not used. In this study, fundamental studies for development of multiple function sensor using 3 axial type of accelerometer and electric resistance property of thermocouple sensors are discussed estimation to stability of structures when happened form active load or fire, and so on.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.257-260
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• 2007

인간의 행위에는 외부환경으로부터 감각정보가 입력되어 반응되는 무의식적인 행동과 뇌에 의한 추론과 인지에 의한 행동으로 분류할 수 있다. 동일한 환경 조건하에서의 인간 행위분류의 통해 활용 적합한 응용프로그램을 개발하여 적용하여 본다. 본 논문에서는 인간의 몸에 부착하여 움직임을 데이터로 분석할 수 있도록 행동인식 시스템을 개발하였다. 인간행동의 인식패턴을 분류하기 위해 Soft-Computing Algorithm을 행위 추출센서에 적용시킨 단독 시스템을 개발하여 센서모듈로부터 인간의 행동 패턴을 분류할 수 있도록 한다. 이러한 센서모듈은 3축 각속도 및 가속도 센서를 부착시킨 모듈로 Micro-Processor를 사용하여 모듈을 구성하였으며, 구축된 모듈은 인간의 몸에 착용하여 인간의 움직임을 디지털 데이터로 변환된다. 변환된 데이터를 무선통신을 통해 워크스테이션에 전달되어 인간행위에 대한 패턴분류 알고리즘 처리가 가능하며, 추출된 데이터를 기반으로 인간의 행동분석과 교정이 이루어 질 수 있도록 한다. 본 논문에서의 최종 시나리오는 운전자의 행동패턴을 이용한 행동 감지 및 서비스 시스템을 구성하는 데에 목적을 둔다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.81-82
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• 2009

본 논문에서는 시각장애인 길 안내 시스템과 같은 다수의 센서를 제어하는 시스템에서 효율적인 디바이스 제어를 위한 쓰레드 구조를 제안한다. 시각장애인의 길안내를 위해 초음파, 적외선 센서, 카메라, GPS, 지자기 센서, 3축 가속도 센서가 사용되며, 이를 효율적으로 제어하기 위해서 각 디바이스마다 각각 쓰레드를 별도로 두며, 뮤텍스 세마포어를 활용해서, 하나의 Zigbee 채널을 공유하기 위한 쓰레드 동기화 기법이 적용된다.