• Journal of Magnetics
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• v.19 no.2
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• pp.151-154
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• 2014

Recent years have seen an increasing range of planar Hall resistive (PHR) sensor applications in the field of magnetic sensing. This study describes a new application of the PHR sensor to monitor a current. Initially, thermal drift experiments of the PHR sensor are performed, to determine the accuracy of the PHR signal output. The results of the thermal drift experiments show that there is no considerable drift in the signals attained from 0.1, 0.5, 1 and 2 mA current. Consequently, the PHR sensor provides adequate accuracy of the signal output, to perform the current monitoring experiments. The performances of the PHR sensor with bilayer and trilayer structures are then tested. The minimum detectable currents of the PHR sensor using bilayer and trilayer structures are $0.51{\mu}A$ and 54 nA, respectively. Therefore, the PHR sensor having trilayer structure is the better choice to detect ultra low current of few tens nanoampere.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.5
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• pp.421-426
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• 2008

The magnetic bio-sensor used the PHR (planar hall resistance) effect generated by the free layer in spin-valve giant magnetoresistance structure of Ta/NiFe/CoFe/Cu/NiFe/IrMn/Ta. The PHR element with micrometer size was fabricated through the photolithograph and dry etching process. The PHR signal with magnetic field was measured under the conditions of with and without single magnetic bead. A single magnetic bead of diameter $2.8\;{\mu}m$ was successfully detected using the PHR sensor. Therefore, the high resolution PHR sensor can be applied to bio-sensor application utilizing the output voltage variation of the PHR signals in the presence and absence of a single magnetic bead.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1832-1853
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• 2018

The personal health record (PHR) system is a promising application that provides precise information and customized services for health care. To flexibly protect sensitive data, attribute-based encryption has been widely applied for PHR access control. However, escrow, exposure and abuse of private keys still hinder its practical application in the PHR system. In this paper, we propose a coordinated ciphertext policy attribute-based access control with user accountability (CCP-ABAC-UA) for the PHR system. Its coordinated mechanism not only effectively prevents the escrow and exposure of private keys but also accurately detects whether key abuse is taking place and identifies the traitor. We claim that CCP-ABAC-UA is a user-side lightweight scheme. Especially for PHR receivers, no bilinear pairing computation is needed to access health records, so the practical mobile PHR system can be realized. By introducing a novel provably secure construction, we prove that it is secure against selectively chosen plaintext attacks. The analysis indicates that CCP-ABAC-UA achieves better performance in terms of security and user-side computational efficiency for a PHR system.

• Journal of the Korean Magnetics Society
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• v.23 no.6
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• pp.200-204
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• 2013

In this study, we have fabricated magnetoresistive sensors of $50{\mu}m{\times}50{\mu}m$ cross type by trilayer structure of antiferromagnetic/nonmagnetic/ferromagnetic. The magnetic signal and magnetic domain of this sensor is measured. The sensor hysteresis loop is not in symmetrical at 0 Oe. This is may be due to the exchange coupling between ferromagnetic layer and anti ferromagnetic layer. This exchange bias value is 20 Oe. The sensor signal is measured at between the applied magnetic field and current. The sensor signal is measured between the applied magnetic field and current at $20^{\circ}$ and $90^{\circ}$ angles. The sensitivity of sensor signals is $20{\mu}V/Oe$ and $7{\mu}V/Oe$ at $20^{\circ}$ and $90^{\circ}$ angles, respectively. In addition, this sensor is also applied for the detection of magnetic bacteria at $20^{\circ}$ angle. From these results, we calculate the stray field of single bacteria is to be $5{\times}10^{-5}$Oe.

• Journal of the Korea Society of Computer and Information
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• v.25 no.8
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• pp.81-87
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• 2020

In this paper, proposes a health status monitoring system for socially marginalized elderly households living alone. This system is implemented by collecting various PHR biometric signals and residential environment information through IoT devices. In addition, the company aims to establish a basic infrastructure that can understand the situation of lonely deaths and implement prevention programs by strengthening the predictive ability through data analysis of the DB server based on PHR and information collected from IoT sensors. The sensor consists of an environmental information collection sensor and a noncontact and wearable sensor for biometric signal collection. A gateway is required to transmit the collected data to the server, and the prototype is presented in this paper. The paper has a discussion purpose of policy task for expanding medical welfare service. The results of this study are believed to help expand services to the socially marginalized and improve the medical environment of the people.

• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.342-348
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• 2021

For the characterization or failure analysis of electronic devices such as PCB (printed circuit boards), the most common method is the measurement of voltage waveforms with an oscilloscope. However, because there are many types of problems that cannot be detected by voltage waveform analysis, several other methods such as X-ray transmission, infrared imaging, or eddy current measurement have been applied for these analyses. However, these methods have also been limited to general analyses because they are partially useful in detecting physical defects, such as disconnections or short circuits. Fundamentally current waveform measurements during the operation of electronic devices need to be performed, however, commercially available current sensors have not yet been developed, particularly for applications in highly integrated PCB products with sub-millimeter fine pitch. In this study, we developed a highly sensitive PHR (planar hall resistance) magnetic sensor for application in highly integrated PCBs. The developed magnetic sensor exhibited sufficient features of an ultra-small size of less than 340 ㎛, magnetic field resolution of 10 nT, and current resolution of 1 mA, which can be applicable for PCB analyses. In this work, we introduce the development process of the magnetic sensing probe and its characteristic results in detail, and aim to extend this pin-type current probe to applications such as current distribution imaging of PCBs.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.308.1-308.1
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• 2007

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.603-604
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• 2020

한국사회는 전통적인 대가족제도가 급속히 해체되고 저 출산 및 고령화로 인한 고령층의 1인 가정의 수가 급속히 증가하고 있는 추세이다. 고령자 1인 가구에 대한 다양한 서비스와 고도화가 필요한 이유이다. 본 연구에서는 1인 가정을 대상으로 IoT 기기를 통한 다양한 PHR 생체 신호와 환경정보을 수집하고 수집된 정보를 바탕으로 건강상태를 모니터링하는 시스템을 제안한다. 제안하는 시스템은 의료기기에서 제공되는 개방형 PHR 데이터의 융합으로 정보 분석 및 예측능력을 강화하고 고독사 상황파악 및 방지 프로그램을 이행할 수 있는 기본 인프라을 구축하고자 한다. 또한 중장년층의 미래에 대한 불확실성을 제거하고 사회복지서비스의 확대를 위한 정책적 과제의 논의적 목적을 가지고 있다. 본 연구의 결과물은 사회 소외 계층에 대한 서비스 확대와 국민의 의료환경 개선에 도움이 될 것으로 사료된다.

• Journal of Magnetics
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• v.12 no.1
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• pp.40-44
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• 2007

The Planar Hall effect in a spin valve structure has been applied as a biosensor being capable of detecting $Dynabeads^{(R)}$ M-280. The sensor performance was tested under the application of a DC magnetic field where the output signals were obtained from a nanovoltmeter. The sensor with the pattern size of $50{\times}100{\mu}m^2$ has produced high sensitivity; especially, the real-time profiles by using that sensor revealed significant performance at external applied magnetic field of around 7.0 Oe with the resolution of 0.04 beads per $\mu m^2$. Finally, a successful array including 24 patterns with the single sensor size of $3{\times}3{\mu}m^2$ has shown the uniform and stable signals for single magnetic bead detection. The comparison of this sensor signal with the others has proved feasibility for biosensor application. This, connecting with the advantages of more stable and high signal to noise of PHR sensor's behaviors, can be used to detect the biomolecules and provide a vehicle for detection and study of other molecular interaction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.83-90
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• 2018

In this paper, we propose an algorithm for analyzing personal health log information in android environment, providing personal health log information in android environment, providing personalized exercise information and monitoring the condition of pedestrians. Personal health log data collection is performed based on raw data of user using MPU6050 sensor based on Arduino. Noise was removed and age threshold was applied to distinguish movement information. In addition, to protect personal information, safety is enhanced by providing anti-compilation prevention and encryption/decryption of APK file, and the result of movement information collection is measured according to sensor location. Experimental results showed that the MPU6050 sensor mounted one the ankle wsa measured 98.97% more accurately then the wrist. In addition, the loading time of SEED 128 bit encryption based DEX file has the average time of 0.55ms, minimizing the overhead.