• Journal of Korea Multimedia Society
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• v.18 no.12
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• pp.1468-1474
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• 2015

Efficient spectrum sharing is an important issue in Device-to-Device (D2D) communications underlaying cellular networks as it can mitigate the interference to cellular users and improve the performance of the systems. In this paper, we formulate the radio resource allocation in D2D communications as a mixed nonlinear integer programing. We show the formulated problem is NP-hard and thus a polynomial time algorithm to solve is not possible. Since such a problem is very hard to obtain the optimal solution within a short running time, we instead propose a fast heuristic suboptimal algorithm to mitigate the interference caused to cellular users and improve the performance of the systems. Simulation results are provided to evaluate the performance of the proposed algorithm.

• Journal of Information Display
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• v.10 no.4
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• pp.184-187
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• 2009

A liquid crystal device with switchable dynamic and memory modes was investigated and developed. The proposed device reveals the splay, $\pi$-twist, and bend states via selective switching among them. In the dynamic mode, the device is operated in the bend state, which exhibits a wide viewing-angle and a fast-response-time due to its self-compensated bend structure and flow-accelerated fast response time, respectively. In the memory mode, the permanent memory characteristics in the splay and $\pi$-twist sates are obtained, respectively. The switching mechanisms of the tristate device are also proposed.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.600-603
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• 2009

The liquid crystal device with switchable dynamic mode and memory mode has been investigated and developed. The proposed device reveals splay, ${\pi}$ twist and bend states by selective switching among them. In the dynamic mode, this device is operated in the bend state which exhibits the wide view angle and fast response time properties due to the self-compensated bend structure and flow accelerated fast response time. In the memory mode, the permanent memory characteristics in the splay and ${\pi}$ twist sates are obtained, respectively. The switching mechanisms of the tristate device are also proposed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.61-66
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• 2010

Pay off reel is the device to release in the form of coil. Every time the device becomes a hassle to exchange, each diameter of two forms has been applied to the coil reel. There is the change of reel diameter of the sleeve portion to be the part of segment geometry. This unit is conducting on 3-dimensional modeling design. The basic strength and deformation of the device could be checked in advance by the basis of 3-d modeling data to perform simulations. The production of each part can be completed and assembled. Conducted for the final product which is tested and measured, all items are satisfied within the limits of targets. Due to the development of this device, the efficiency on operations can be increased and the production time becomes shortened.

• Journal of the Semiconductor & Display Technology
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• v.12 no.2
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• pp.73-78
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• 2013

This paper proposes a portable electrocardiograph and smart device-based heart health monitoring and risk notification system. The proposed system consists of a portable electrocardiograph and a smart device for a system user, and a web-based monitoring system for observers. This system can improve the convenience and efficiency of measurement by using a light-weight portable electrocardiograph and a smart device. In addition, any authorized person such as caregiver or family member who is not related to medical institution can monitor users'heart health in real-time using the web-based monitoring system. Therefore, a user and authorized remote observers can efficiently monitor and manage user's heart health in daily-life even without any medical institution's help, and can preemptively deal with any possible dangerous situations, such as degeneration of a cardiac disorder and sudden cardiac death.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.501-504
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• 2013

Smart Device의 성능은 기존 Embedded System과는 비교가 무의미할 만큼 성장하였다. 하지만 실시간으로 외부의 다양한 데이터를 처리하기 위해서는 아직 Smart Device의 자원이 충분하지 않다. 이를 해소하기 위한 방안으로 신호의 처리와 관리는 풍부한 자원을 가진 서버에서 수행하고 스마트 기기는 신호 전달 및 처리 결과 수신의 제한적인 역할을 수행할 수 있는 Cloud System이 필요하며 덧붙여, 시스템을 다양한 계측 분야에서 유연하게 활용하기 위해 여러 종류의 신호들을 다양하게 처리해 줄 수 있는 Cloud Cluster와 이를 관리해줄 Platform의 구축이 이뤄져야한다. 본 연구는 그 중에서도 실시간성을 요하는 모델을 고려하여 Real Time Cloud System Platform의 구축을 위한 기반연구로서, Smart Device와 Senser 간의 Interoperability에 초점을 두고 Proto Type의 구현과 몇몇 세부 쟁점에 대한 실험 및 연구 분석 결과를 포함한다.

• Journal of Institute of Convergence Technology
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• v.4 no.2
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• pp.17-21
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• 2014

This paper presents the effects of the time delay on the stability of the haptic system that includes a virtual wall and a first-order-hold method. The model of a haptic system includes a haptic device model with a mass and a damper, a virtual wall model, a first-order-hold model and a time delay model. In this paper, the time delay is considered as the computational time delay that is assumed to be as much as the sampling time. As the time delay increases, the maximal available stiffness of a virtual wall model is reduced reversely. The relation among the time delay and the maximum available stiffness, the mass and the damper of the haptic device are analyzed using the MATLAB simulation.

• Journal of Korean Neurosurgical Society
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• v.41 no.2
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• pp.77-81
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• 2007

Objective : In a variety of thoracolumbar diseases, corpectomy followed by interbody bone graft and anterior instrumentation has allowed direct neural decompression and reconstruction of the weight-bearing column by short segments fusion. In this study, we compared spinal stability of the two different anterior thoracolumbar instruments : Z-plate and Kaneda device representing plate and two-rods type, respectively. Methods : A retrospective review was performed for all the patients with thoracolumbar diseases or traumas treated with anterior corpectomy, autologous iliac bone graft, and fixation with instruments from 1996 to 2000. For the anterior instrumentation, Z-plate or Kaneda device was used for 24 [M:F=5:9, average age=37] and 12 [M:F=9:3, average age=41] patients, respectively. The plain AP and lateral flexion-extension films were taken immediately after surgery and at each follow-up. The sagittal and coronal Cobb's angles at the operation segments were used to observe the change of initial fixation status. The surgical time length and bleeding amount of the two groups were compared. Intra-operative and post-operative instrument associated complications were evaluated. Student t-test was used for statistical analysis and p-value less than 0.05 was considered to be significant. Results : Mean follow-up durations for Z-plate and Kaneda device were 24 and 21 months, respectively. The fusion rate was 91% for Z-plate and 100% for Kaneda device. Two cases of Z-plate group showed instrumentation failure during the follow up period, in which additional surgery was necessary. The mean differences of sagittal Cobb's angles among the AP images immediate after surgery and at follow-up were 7 and 2 degrees for Z-plate and Kaneda device, respectively [p<0.05]. The mean differences of coronal Cobb's angles were 5 and 2 degrees for Z-plate and Kaneda device, respectively [p<0.05]. No Intra-operative complication has occurred in both groups. There was no difference in surgery time and bleeding amount between two groups. Conclusion : We think that Kaneda device [rod type] is stronger than Z-plate [plate type] to keep the spinal stability after anterior thoracolumbar surgery.

• Journal of the Ergonomics Society of Korea
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• v.30 no.6
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• pp.765-773
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• 2011

Objective: This study aims towards exploring a model of the HCI evaluation methods to improve the usability of mobile device, based on a case of a Mobile PDA system in a Museum context. Background: Mobile PDA systems in a Museum context is widely utilized for the educational purposes, but it is criticized for low usability that the device only play a role in textbooks on legs without any interactive educational activities. Therefore, the usability improvements on the mobile PDA system should be considered. Method 1: This model was developed with a combination of the expert review and the user testing, and with a combination of the qualitative and quantitative studies. In more details, first of all, a qualitative study was conducted as a combination of three different methods: 1) expert review with heuristics, 2) interviews with persons working in a museum, and 3) contextual enquiry. Results 1: The experts review provided with critical usability issues, and the semi-constructive interview helped to understand the background of the mobile device. Lastly, the contextual enquiry showed user experience problems and directions of improving the device from user's perspective. Method 2: Based on the results of the qualitative study, a questionnaire was designed. Results 2: The analysis of the quantitative study was conducted to generalize the problems, and prioritize the direction of improving the device within the limitation of the cost and time in a museum. Conclusion: This study has implications in developing an example of a HCI evaluation model to improve the user experience of the mobile device as well as finding problems and directions of how to improve the mobile PDA systems in the museum. Application: In fact, most of the studies related to the evaluation of the mobile device have been conducted in a laboratory context due to the cost and time. This paper, however, attempted to apply to various HCI research techniques from different constituents in real context.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2206-2208
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• 2002

In this paper, using the communication port between PC(Personal Computer) and DC/STEP MOTOR DEVICE that movement and measurement of motor. Communication port used serial port and movement order transmits by communication port. Consequence of motor device movement displays to tile DC/STEP MOTOR DEVICE APPLICATION. This connection is using the serial port instead of parallel port faster than response time And this application is easier than existing application.