• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.27-35
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• 2016

A Low jitter dual output frequency synthesizer for smart audio devices is described in this paper. It has been fabricated in a 1.8 V Dongbu $0.18-{\mu}m$ CMOS process. Output frequency is controlled by 3 rd order Sigma-Delta Modulation and digital divider. The frequency synthesizer has a size of $0.6mm^2$, frequency range of 0.6-200 MHz, loop bandwidth of 350 kHz, and rms jitter of 11.4 ps-21.6 ps.

• The Journal of Society for e-Business Studies
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• v.21 no.4
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• pp.15-28
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• 2016

As the industry of Mobile Internet has been gradually developed, the major device for accessing the web is predicted to shift from PC to Mobile devices in the near future. This drastic increase of demand in Mobile devices has drawn a more convenient standard of living by transcending time and space in our lives, however, it triggered various side effects such as a digital divide. This study was conducted to analyze how people utilize the contents via Mobile devices and their active attitude toward Mobile Internet by dividing individual characteristics into generations, education level and income level, and also identify whether Mobile contents utilization has an effect on the active attitude. The research results could be used for establishing a policy to narrow the gap in Mobile contents use and active attitude by individual characteristics.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.1-11
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• 2017

Recently that require digital signatures handwritten for personal use customer information and agree to the Terms of Service agreement or a general sign up. Signature system including an existing handwritten signature are a problem, which may be a platform-dependent, as well as the environment in which to perform the signature vary according to device Status of presence because it is being utilized is implemented on the service platform itself within each company. In this paper, we designed and implemented an integrated system handwritten signature as possible using a cross-browser way to store the handwritten two-dimensional coordinates based on the jQuery it is interspecific directly integrated browser environment. iOS, Android, was tested in an integrated web browser in heterogeneous environments, including PC, it was confirmed that all handwritten signature function is working properly.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.103-110
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• 2006

Turbo code, a kind of error correction coding technique, has been used in the field of digital mobile communication system. As the number of iterations increases, it can achieves remarkable BER performance over AWGN channel environment. However, if the number of iterations Is increases in the several channel environments, any further iteration results in very little improvement, and requires much delay and computation in proportion to the number of iterations. To solve this problems, it is necessary to device an efficient criterion to stop the iteration process and prevent unnecessary delay and computation. In this paper, it proposes an efficient and simple criterion for stopping the iteration process in turbo decoding. By using variance values of noise derived from mean values of LLR in turbo decoder, the proposed algorithm can largely reduce the computation and average number of iterations without BER performance degradation. As a result of simulations, the computation of the proposed algorithm is reduced by about $66{\sim}80%$ compared to conventional algorithm. The average number of iterations is reduced by about $13.99%{\sim}15.74%$ compared to CE algorithm and about $17.88%{\sim}18.59%$ compared to SCR algorithm.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.73-81
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• 2011

The WBAN(Wireless Body Area Network) technology is a short distance wireless network which provides each device's interactive communication by connecting devices inside and outside of body located within 3 meters. Standardization on the physical layer, data link layer, network layer and application layer is in progress by IEEE 802.15.6 TG BAN. The The WBAN servides consists of both medical and non-medical applications. The medical application service uses the sensor that transfer the periodic traffic and have different data rates. It uses GTS method to guarantee QoS. In this paper, a new method is proposed, which are suitable design for MAC Protocol. Firstly, MAC frame structure and a primitive based on the WBAN are proposed. Secondly, we proposed the GTS algorithm improved the channel utilization based on the WFQ(Weighted Fair Queuing). The proposed scheduling method is improved channel utilization compared with i-Game(Round Robin scheduling method).

• Journal of Sensor Science and Technology
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• v.20 no.3
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• pp.172-177
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• 2011

Finger patients can't use their hands because of the paralysis their fingers. Their fingers are recovered by rehabilitating training, and the rehabilitating extent can be judged by measuring the pressing force to be contacted with two fingers(thumb and first finger, thumb and middle finger, thumb and ring finger, thumb and little finger). At present, most hospitals have used a thin plastic-plate for measuring the two-finger grasping force, and we can only judge that they can grasp the plate with their two-finger through it, because the plate can't measure the two-finger grasping force. But, recently, the force measuring system for measuring two-finger grasping force was developed using three-axis force sensor, but it is very expensive, because it has a three-axis force sensor. In this paper, two-finger force measuring system with a one-axis force sensor which can measure two-finger grasping force was developed. The one-axis force sensor was designed and fabricated, and the force measuring device was designed and manufactured using DSP(Digital Signal Processing). Also, the grasping force test of men was performed using the developed two-finger force measuring system, it was confirmed that the grasping forces of men were different according to grasping methods, and the system can be used for measuring two-finger grasping force.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.13-19
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• 2016

The PSK (Pre-shared Secret Key) based method is appropriate for the IoT environment consisting of lightweight devices since this method requires less computing time and energy than the method to configure the session key based on the public key algorithm. A fundamental prerequisite for the PSK based method is that PSK should have been configured between the communication entities safely in advance. However, in case of a small sensor or actuator, no input and output interface such as keyboard and monitor required for configuration exists, so it is more difficult to configure PSK for such lightweight devices safely in the IoT environment than the previous Internet devices. Especially, normal users lack expertise in security so they face difficulty in configuration. Therefore, the default value configured at the time of manufacturing at factories is used or the device installer configures PSK in most cases. In such case, it is a matter for consideration whether all installers and manufacturers can be trusted or not. In order to solve such problem, this paper proposes a secure bootstrapping scheme, which utilizes the NFC (Near Field Communication) as an OOB (Out-Of-Band) channel, for lightweight devices with limited resources.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.7
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• pp.61-67
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• 2009

This paper reports an Integer-N phase locked loop (PLL) frequency synthesizer which was implemented in a 250nm standard digital CMOS process for a UHF RFID wireless communication system. The main blocks of PLL have been designed including voltage controlled oscillator, phase frequency detector, and charge pump. The LC VCO has been used for a better noise property and low-power design. The source and drain juntions of PMOS transistors are used as the varactor diodes. The ADF4111 of Analog Device has been used for the external pre-scaler and N-divider to divide VCO frequency and a third order RC filter is designed for the loop filter. The measured results show that the RF output power is -13dBm with 50$\Omega$ load, the phase noise is -91.33dBc/Hz at 100KHz offset frequency, and the maximum lock-in time is less than 600us from 930MHz to 970MHz.

• 한국HCI학회:학술대회논문집
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• 2006.02b
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• pp.290-295
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• 2006

지금까지 디지털 기기의 진화 과정을 볼 때 오직 기능적 발전만이 추구되고 그것을 사용하는 사용방식에 대한 진지한 고민은 부재하였다. 때문에 디지털 기기가 갖고 있는 버튼 위주의 획일적 사용방식은 사용자보다는 기기 중심의 디자인이 우선시되는 사회적 병리현상을 야기하고 있다. 반면 오랜 기간 인간이 다루어 온 전통적인 아날로그 도구들은 작업의 특성과 작업자의 상황에 맞도록 다양한 사용성을 고려하며 진화되어 왔다. 따라서 본 연구에서는 사용자들에게 익숙한 아날로그적 경험을 디지털 기기의 인터랙션 디자인에 적용시켜 보다 인간 중심적인 디지털 도구를 제안 하고자 한다. 연구의 목표는 다양한 기능이 복합된 대표적 디지털 기기인 휴대폰에 아날로그 경험을 접목시킴으로써 전통적인 도구들과 같이 디지털 기기의 자연스러운 인터랙션 스타일을 디자인하는 것이다. 이를 위하여 한정된 디바이스로 다양한 기능들을 조작해야 하는 모바일 기기에 적합한 아날로그 경험들에 대한 연구가 진행되었고, 기호와 조합으로 이루어진 카드놀이 메타포에서 그 단서를 발견할 수 있었다. 따라서 본 연구는 메타포로 제시한 카드놀이를 하며 일어나는 행위와 경험을 멀티미디어 휴대폰에 접목시켜 새로운 사용 방식을 제안하는 것이다. 예를 들어, 메뉴 선택의 경우 카드를 펼쳐 원하는 카드를 뽑으면 되는데 아래로 펼치면 그 카드의 수직 메뉴가, 옆으로 펼치면 그 카드의 수평 메뉴가 나타난다. 또 메뉴 안의 내용을 찾을 때는 카드를 뒤로 넘겨서 보게 되고 자신만의 개인적인 내용을 보고자 할 때는 카드를 은밀히 보는 듯한 행위를 취하면 된다. 즉 멀티미디어 폰 안의 내용뿐 아니라 사용하는 행위 자체도 하나의 즐거움이 되도록 카드놀이 경험을 새로운 인터랙션 스타일로 개발하여 그 가능성을 연구하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1744-1749
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• 2013

Acoustic feedback is perceived as whistling or howling, which is a major complaint of hearing-aids users. Acoustic feedback cancellation is important in hearing-aids because acoustic feedback degrades performance of the hearing aid device by reducing maximum insertion gain. Adaptive systems for estimate acoustic feedback path and feedback suppression algorithms have been proposed in order to solve this problem. A typical feedback cancellation algorithm is LMS(least mean squares) because of its computational efficiency. However it has problem of convergence performance in high correlated input signal. In this paper, we propose a new variable step-size normalized LMS(least mean squares) algorithm using VAD(voice activity detection) to overcome the limitation of the LMS algorithm. The VAD algorithm is GSAP(global speech absence probability) and the feedback cancellation algorithm is normalized LMS. The proposed algorithm applies different step-size between voice and non-voice using VAD, for high stability, fast convergence speed and low misalignment when correlated inputs, such as speech. The result of simulation with white noise mixed speech signal, the proposed algorithm shows high performance then traditional algorithm in terms of stability, convergence speed and misalignment.