• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 춘계학술대회
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• pp.606-608
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• 2015

IoT 환경에서 디바이스간의 관계를 맺기 위해서는 디바이스를 탐색하는 작업이 선행되어야 한다. 주변의 디바이스를 탐색하기 위해 새로운 디바이스는 탐색 신호를 송신하고 이를 수신하는 디바이스는 신호의 세기를 판별하여 송신한 디바이스와의 거리 정보를 파악한다. 기존에 사용되고 있는 M2M(Machine to Machine) 방식은 하나의 디바이스에서 주변의 모든 디바이스에게 탐색 신호를 보내고, 주변의 디바이스들이 증가할수록 탐색 시간이 길어지고, 원거리의 디바이스일수록 정보의 손실이 발생하는 문제점이 존재하였다. 본 논문에서는 기존의 디바이스 탐색 방식의 문제점을 보완할 방법으로 새로운 디바이스가 주변의 디바이스를 탐색할 때의 탐색 시간을 단축하고, 근거리의 디바이스와의 탐색 신호를 주고받을 때의 정보 손실을 줄이기 위해 SNR(Signal to Noise Ratio)의 세기를 높일 수 있는 알고리즘을 제안한다.

• 대한전자공학회논문지TC
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• 제47권7호
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• pp.72-79
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• 2010

셀룰러 네트워크 내에서 cellular 링크와 무선 자원을 공유하는 device-to-device(D2D) 링크는 자신이 속한 셀룰러 네트워크에 심각한 간섭을 줄 가능성이 높기 때문에 그것을 방지하기 위해서는 무선 자원 할당의 최적화가 중요하다. 본 논문에서는 D2D 링크가 자신의 간섭을 최소화하면서 효율적으로 cellular 링크와 공존하기 위해서 subset reuse 방법을 기반으로 하는 자원 할당 기법에 대해 제안한다. Cellular 링크와 D2D 링크 주파수 자원 할당의 효율성을 높이기 위하여 셀 상황에 따라 가변적인 subset 크기를 가지는 group-wise subset reuse 방법을 제안한다. 또한, cellular 링크가 같은 주파수 대역을 사용하는 D2D 전송에 의해 간섭을 받는 경우, D2D 링크의 power를 최적화하여 cellular 링크로의 간섭을 최소화하게 된다. 컴퓨터 시뮬레이션 결과를 통하여 link SINR에서 성능 이득을 가지며, local traffic이 증가할수록 전체 cell throughput이 높아짐을 보였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.112-112
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• 2012

Graphene has been considered as one of the potential post Si-materials due to its high mobility. [1] However, since graphene is semi-conductor with zero band gap, it is difficult to achieve high Ion/Ioff ratio, one of the most important requirements for commercial devices. There have been many attempts to open its band gap for high Ion/Ioff ratio, but most of them end up lowering the mobility. [2-5] Thus, we proposed and demonstrated a new device structure for graphene transistor based on one of the unique properties of graphene for high Ion/Ioff: using this approach, we were able to achieve the ratio over $10^5$. [6] Our device has several major advantages over previously proposed graphene based electronic devices. Since our device does not alter the given properties of graphene, such as opening the band gap, it has no fundamental issues on mobility degradations. In addition, our device is fully compatible with current Si technology and we were able to fabricate the devices with 6 inch wafer scale with CVD (Chemical Vapor Deposition) grown graphene. In this presentation, we will discuss about the details of our graphene device including the device structure and the detailed understanding of working mechanism. We will present device characteristics including I-V curves with $10^5$ on/off ratio. We will also present the performance of an inverter based on our devices. Finally, we will discuss the current issues and their potential solutions.

• 품질경영학회지
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• 제46권3호
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• pp.411-424
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• 2018

Purpose: The purpose of this study is to improve submarine TACM launcher system safety device performance. Methods: In this study, EPLD(Electrically Programmable Logic Device) control and time sharing method to the safety device actuator motor and discrete signal processor in launch control panel were used to resolve unusual performance of safety system. Results: The result of this study are as follows; First, sporadic stopping of safety device actuator motor due to insufficient In-Rush current was resolved. Second, repeat of safety device condition as lock & release due to chattering for motor activating was resolved. Third, simultaneous release function for safety device actuator was available. Conclusion: The unusual performance of function for submarine TACM launcher system was overcame by applying EPLD control and time sharing method. The suggestions were proved by performance test in the pressure chamber. The results of this study enhanced survivability of ${\bigcirc}{\bigcirc}{\bigcirc}$ class submarine from enemy torpedo.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.548-553
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• 2011

알루알루미늄 분말과 물의 연소 특성을 연구하기 위한 장치를 고안하였다. 알루미늄 분말의 점화를 포함한 연소특성은 초기온도, 압력, 당량비등에 의존하게 되므로 이러한 인자를 변화시켜 연소환경을 적응시킬 수 있는 장치를 설계하였다. 연소 시험 장치는 메탄 연소기, 물공급장치, 알루미늄 분말 정량 공급장치, 선형 형태의 연소기 및 제어장치로 구성되어 있다. 각각의 장치들은 필요한 물질을 정량적으로 공급할 수 있는 기능을 가지고 있으며, 정해진 시험 과정에 따라 자동으로 제어될 수 있도록 설계되었다. 제작된 장치를 시운전하여 각 구성품이 정상작동하였을 때, 알루미늄 분말이 연소되는 것을 확인할 수 있었다.

• Physical Therapy Rehabilitation Science
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• 제10권3호
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• pp.374-378
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• 2021

Objective: Bilateral movement training is an effective method for upper extremity rehabilitation of stroke. An approach to induce bilateral movement through functional electrical stimulation is attempted. The purpose of this study is to develop an EMG-triggered functional electrical stimulation device for upper extremity bilateral movement training in stroke patients and test its feasibility. Design: Feasibility and Pilot study design. Methods: We assessed muscle activation and kinematic data of the affected and unaffected upper extremities of a stroke patient during wrist flexion and extension with and without the device. Wireless EMG was used to evaluate muscle activity, and 12 3D infrared cameras were used to evaluate kinematic data. Results: We developed an EMG-triggered functional electrical stimulation device to enable bilateral arm training in stroke patients. A system for controlling functional electrical stimulation with signals received through a 2-channel EMG sensor was developed. The device consists of an EMG sensing unit, a functional electrical stimulation unit, and a control unit. There was asymmetry of movement between the two sides during wrist flexion and extension. With the device, the asymmetry was lowest at 60% of the threshold of the unaffected side. Conclusions: In this study, we developed an EMG-triggered FES device, and the pilot study result showed that the device reduces asymmetry.

• 한국통신학회논문지
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• 제41권11호
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• pp.1619-1629
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• 2016

본 논문은 기지국 협력이 가능한 Device-to-Device 통신 모델에서의 효율적인 전송 프로토콜에 대해 연구하였다. 두 개의 직접통신 송수신단 쌍이 기지국의 상향링크, 하향링크 통신채널을 활용하여 독립적인 메시지를 전송하는 모델에 대해 고려하였다. 제안기법의 경우, 첫 번째 단계에서 송신단은 메시지를 전송하고 기지국과 수신단은 이를 수신하게 된다. 두 번째 단계에서 기지국은 메시지의 XOR를 수신단에게 전송하여 최종적으로 수신단은 첫 번째 단계에서 수신한 신호와 두 번째 단계에서 수신한 신호를 통하여 자신의 메시지를 복원하게 된다. 기존의 직접 통신의 경우, 자신의 메시지 디코팅에 실패하면 아웃티지가 발생하지만, 제안기법의 경우 첫 번째 단계에서 두 메시지 중 하나만 디코딩이 가능하면 두 번째 단계에서 수신한 메시지의 XOR를 통해 자신의 메시지를 복원 가능하다. 본 논문은 제안기법의 아웃티지 기반 전송율을 분석하고 또한 모의실험을 통하여 제안기법이 기존 기법 대비 아웃티지 성능을 향상시킬 수 있음을 보였다.

• Journal of Korean Neurosurgical Society
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• 제43권1호
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• pp.26-30
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• 2008

Objective : The authors developed a stereotactic device for irradiation of small animals with Leksell Gamma Knife Model C. Development and verification procedures were described in this article. Methods : The device was designed to satisfy three requirements. The mechanical accuracy in positioning was to be managed within 0.5 mm. The strength of the device and structure were to be compromised to provide enough strength to hold a small animal during irradiation and to interfere the gamma ray beam as little as possible. The device was to be used in combination with the Leksell G-$frame^{(R)}$ and $KOPF^{(R)}$ rat adaptor. The irradiation point was determined by separate imaging sequences such as plain X-ray images. Results : The absolute dose rate with the device in a Leksell Gamma Knife was 3.7% less than the value calculated from Leksell Gamma $Plan^{(R)}$. The dose distributions measured with $GAFCHROMIC^{(R)}$ MD-55 film corresponded to those of Leksell Gamma $Plan^{(R)}$ within acceptable range. The device was used in a series of rat experiments with a 4 mm helmet of Leksell Gamma Knife. Conclusion : A stereotactic device for irradiation of small animals with Leksell Gamma Knife Model C has been developed so that it fulfilled above requirements. Absorbed dose and dose distribution at the center of a Gamma Knife helmet are in acceptable ranges. The device provides enough accuracy for stereotactic irradiation with acceptable practicality.

• 대한조선학회 특별논문집
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• 대한조선학회 2015년도 특별논문집
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• pp.50-55
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• 2015

Application of newly conceptualized Anti-Splash Devices designed for COT vent pipes were studied on a P/V valve located on the upper deck of an oil carrier vessel. Anti-Splash devices are used in the shipbuilding industry in order to avoid oil overflow and spray accidents caused by excess pressure and vacuum condition in the cargo oil tanks. These conditions are caused by the transverse and longitudinal sloshing forces that arise from ship motion during sea voyages. The main issue with existing Anti-Splash device model is flux at the outlet of the Anti-Splash Device, and so, new conceptual models for the Anti-Splash device were developed and compared to existing Anti-Splash device model using CFD analysis. Transient analysis was used to capture the flow and velocity of each model and a comparative analysis was performed between old and new-concept models. This data was used to determine the optimal design parameters in order to develop an optimized Anti-Splash Device. A Factory acceptance test was performed on the new-concept models in order to verify the performance and efficiency against their design requirements and other criterion. The final step performed was to apply the optimized Anti-Splash Device models for COT vent pipes to an actual vessel and verify performance through a seawater cargo operation during a sea voyage as per the ship owner's request. The patent for the aforementioned device was obtained by the Korean Intellectual property Office dated Dec. 18th,2014.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2844-2851
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• 2011

The purpose of this study is to set up an acoustic prediction technique and to perform the IL test of scale down noise reducing device for the development of the noise reducing device as the development of 400km/h class high speed train. First of all, the IL prediction of noise reducing device was performed with the 2D BEM method. And the noise test of scale down noise reducing device in anechoic chamber was performed for the verification of acoustic prediction technique and IL performance evaluation. As the results, the acoustic prediction technique for the development of noise reducing device was verified because the averaged IL difference between prediction and test is in 2dB(A). And the measured IL value of noise reducing device is less than 2dB(A), and additional IL with polyester absorption material is increased about 0.5dB(A).