• International Journal of Advanced Culture Technology
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• 제5권2호
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• pp.54-62
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• 2017

Currently, falling to industrial field workers is causing serious injuries. Therefore, many researchers are actively studying the fall by using acceleration sensor, gyro sensor, pressure sensor and image information.Also, as the spread of smartphones becomes common, techniques for determining the fall by using an acceleration sensor built in a smartphone are being studied. The proposed method has complexity due to fusion of various sensor data and it is still insufficient to develop practical application. Therefore, in this paper, we use acceleration sensor module built in smartphone to collect acceleration data, propose a simple falling algorithm based on accelerometer sensor data after normalization and preprocessing, and implement an Android based app.

• 대한안전경영과학회지
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• 제20권2호
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• pp.37-44
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• 2018

The Location Based Service is growing rapidly nowadays due to the universalization of the use for smartphone, and therefore the location determination technology has been placed in a very important position. This study suggests an algorithm that can provide the estimate of users' location by using smartphone sensors. And in doing so we will propose a methodology for the creation and update of indoor map through the more accurate position estimation using smartphone sensors such as acceleration sensor, gyroscope sensor, geomagnetic sensor and rotation sensor.

• International journal of advanced smart convergence
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• 제10권3호
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• pp.10-16
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• 2021

In this paper, we devise a Shapley-value-based covert channel in smartphones. More specifically, unlike ordinary use of Shapley value in cooperative game, we make use of a series of Shapley values, which are computed from sensor data collected from smartphones, in order to create a covert channel between encoding smartphone and decoding smartphone. To the best of our knowledge, we are the first to contrive covert channel based on Shapley values. We evaluate the encoding process of our proposed covert channel through simulation and present our evaluation results.

• 한국멀티미디어학회논문지
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• 제20권8호
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• pp.1200-1207
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• 2017

Sensors in a smartphone can be used to measure various physical quantities. In this paper, we propose an object localization scheme in a three dimenstional using a smart phone. The proposed scheme estimates the location of an object by observing it from several different points. The direction to the target object and the locations of the observation points are collected at each observation point using the location sensor and the orientation sensor in the smartphone. Based on these observations, the proposed scheme derives three dimensional line of sight vectors and estimates the location of the target object that minimizes the estimation error. We implemented the proposed scheme on an Android smartphone and tested its performance by estimating the height of a building and characteristics of 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.

• 한국지능시스템학회논문지
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• 제25권1호
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• pp.48-56
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• 2015

본 논문에서는 지자기센서와 스마트폰을 사용하여 개인이동시스템(PMS)을 구현한다. 지자기센서를 사용한 PMS 제어 시스템은 탑승자가 원하는 방향으로 스마트폰을 향하게 하면 PMS는 탑승자가 원하는 방향으로 이동한다. 본 논문에서 제안한 스마트폰 제어 PMS는 지자기센서를 사용함으로써 버튼 조작에 의한 제어보다 더 직관적으로 PMS를 제어하므로 사용자에게 더욱 편리한 인터페이스를 제공한다. 그리고, PMS에 장착된 모터의 기계적 특성을 보정하기 위하여 지자기센서가 사용되었다. 또한, 본 논문은 지자기센서 기반의 PMS의 제어방법으로 절대방향과 상대방향 제어방법을 제안한다. 실험 결과로서 제안된 두 가지 방법으로 지자기센서 기반의 PMS가 편리하고 효과적으로 제어되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권12호
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• pp.5805-5825
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• 2019

Smartphones are important platforms because of their sophisticated computation, communication, and sensing capabilities, which enable a variety of applications in the Internet of Things (IoT) systems. Moreover, advancements in hardware have enabled sensors on smartphones such as environmental and chemical sensors that make sensor data collection readily accessible for a wide range of applications. However, dynamic, opportunistic, and heterogeneous mobility patterns of smartphone users that vary throughout the day, which greatly affects the efficacy of sensor data collection. Therefore, it is necessary to consider phone users mobility patterns to design data collection schedules that can reduce the loss of sensor data. In this paper, we propose a mobility-based weighted adaptive opportunistic scheduling framework that can adaptively adjust to the dynamic, opportunistic, and heterogeneous mobility patterns of smartphone users and provide prioritized scheduling based on various application scenarios, such as velocity, region of interest, and sensor type. The performance of the proposed framework is compared with other scheduling frameworks in various heterogeneous smartphone user mobility scenarios. Simulation results show that the proposed scheduling improves the transmission rate by 8 percent and can also improve the collection of higher-priority sensor data compared with other scheduling approaches.

• 정보보호학회논문지
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• 제25권6호
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• pp.1477-1484
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• 2015

스마트폰 기반 금융 산업의 발달로 스마트폰을 이용한 인증 기법에 관심이 높아지고 있다. 다양한 생체 기반 사용자 인증 방식이 존재하지만 아직까지 스마트폰 기반 사용자의 걸음 패턴(gait) 인증 방식은 뚜렷한 발전을 보이고 있지 않다. 본 논문에서는 스마트폰에 기본적으로 탑재된 가속도 센서를 이용해 사용자를 인증하는 방법을 제안한다. 구체적으로, 스마트폰에서 수집한 데이터를 3D 변환하여 자세를 교정하고, 변환된 데이터에서 특징을 추출한 뒤 주성분 분석, 가우시안 혼합 모델링 과정을 거쳐 데이터를 학습 시킨다. 다음으로, 신뢰구간 검증 방식을 사용해 사용자 데이터를 검증했다. 그 결과, 통제 요인과 한계점이 많았던 선행 가속도 연구들과 달리 최소한의 통제 요인과 높은 정확도(약 96%)로 사용자 인증이 가능함을 입증했다.

• 한국멀티미디어학회논문지
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• 제17권12호
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• pp.1437-1445
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• 2014

A smartphone has very limited input methods regardless of its various functions. In this respect, it is one alternative that sensor motion recognition can make intuitive and various user interface. In this paper, we recognize user's motion using acceleration sensor, magnetic field sensor, and gyro sensor in smartphone. We try to reduce sensing error by gradient descent algorithm because in single sensor it is hard to obtain correct data. And we apply vector quantization by conversion of rotation displacement to spherical coordinate system for elevated recognition rate and recognition of small motion. After vector quantization process, we recognize motion using HMM(Hidden Markov Model).

• 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.