• 한국통신학회논문지
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• 제39C권8호
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• pp.681-687
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• 2014

최근 몇 년 간 스마트 폰과 같은 개인 스마트 디바이스들의 확산으로 인해 인터넷 트래픽이 급증하고 있다. 이는 지상에 있는 기지국뿐만 아니라 건물, 버스, 철도, 선박 등에 설치된 AP(Access Point)나 기지국에도 심각한 과부하를 야기한다. 따라서 이를 해소하기 위해 크루즈선과 같은 선박 내부에서 효과적인 콘텐츠 분배를 위한 통신시나리오를 제안한다. 또한 제안한 시나리오 안에서 기존의 단말 간 직접통신(D2D: Device-to-Device)을 확장하여 다중 단말 간(MD2MD: Multi-Device-to-Multi-Device) 직접 통신 네트워크를 구성하고 이에 적합한 전송기법을 제시한다. 제안한 선박 내 다중 단말 간 직접통신 방식은 STBC(Space-Time Block Coding) 전송기법, SM(Spatial Multiplexing) 전송기법, 그리고 하이브리드 STBC-SM 기법을 비교분석하여 전송률(throughput) 관점에서 향상된 성능을 보인 전송기법을 채택했다. 제안한 방식은 선박 내 통신 특히 사용자의 수가 많아 트래픽이 심하여 선박 내 설치된 AP의 과부하가 심할 경우 이를 분배하고 사용자들에게 효율적으로 보다 질 높은 콘텐츠를 제공할 수 있는 기술로 기대된다.

• 전자공학회논문지
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• 제51권10호
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• pp.3-10
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• 2014

본 논문에서는 인지 기반 중첩 융합 네트워크 환경 하에서의 사용자의 위치정보를 토대로 사용자 단말기의 전력소모감소와 간섭신호의 저감효과를 극대화하기 위한 기본적인 D2D(device-to-device)시스템을 제시하고 무선 전송 환경에서의 시스템 성능을 분석하고자 한다. 단말기의 기능성이 좋아짐에 따라 스마트한 지능을 기반으로 자원의 효과적 활용에 적합한 개별 이종 네트워크의 특성분석과 특성을 반영하는 시스템 측면의 최적화가 중요하다고 할 수 있다. 본 논문에서는 사용자 이동특성에 기반하여 인접 단말기와의 직접 통신하는 절차를 구성하여 단말기 간 직접 통신에 다중안테나 기술을 적용할 경우 이에 따른 FER(frame error rate) 등의 성능특성을 살펴보고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2631-2649
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• 2021

Device-to-Device (D2D) communication is one of the enabling technologies for 5G networks that support proximity-based service (ProSe) for wireless network communications. This paper proposes a power control algorithm based on the Nash equilibrium and game theory to eliminate the interference between the cellular user device and D2D links. This leadsto reliable connectivity with minimal power consumption in wireless communication. The power control in D2D is modeled as a non-cooperative game. Each device is allowed to independently select and transmit its power to maximize (or minimize) user utility. The aim is to guide user devices to converge with the Nash equilibrium by establishing connectivity with network resources. The proposed algorithm with pricing factors is used for power consumption and reduces overall interference of D2Ds communication. The proposed algorithm is evaluated in terms of the energy efficiency of the average power consumption, the number of D2D communication, and the number of iterations. Besides, the algorithm has a relatively fast convergence with the Nash Equilibrium rate. It guarantees that the user devices can achieve their required Quality of Service (QoS) by adjusting the residual cost coefficient and residual energy factor. Simulation results show that the power control shows a significant reduction in power consumption that has been achieved by approximately 20% compared with algorithms in [11].

• 정보와 통신
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• 제30권12호
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• pp.97-104
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• 2013

최근 스마트폰, 태블릿등과 같은 모바일 인터넷 기기들이 폭증함에 따라 Bluetooth 또는 WiFi P2P와 같은 기존 단말 간 통신 기술에 비해 넓은 전송 범위와 높은 QoS (Quality of Service)를 보장할 수 있는, 새로운 근접 서비스 기반(Proximity-based service)의 단말 간 (Device-to-device: D2D) 통신 기술에 대한 필요성이 대두되고 있다. 본 논문에서는 D2D 기술을 이용한 서비스 및 해당 서비스를 위한 요구사항들과 이를 지원하기 위한 요소기술들, 그리고 IEEE와 3GPP에서 활발히 진행되고 있는 D2D 통신 기술의 표준화 동향을 살펴보고자 한다.

• 대한방사선기술학회지:방사선기술과학
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• 제46권2호
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• pp.151-157
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• 2023

The purpose of this study was to develop an assist device that could correct and support patient position during biopsy on computed tomography (CT) using 3D printing technology. The development method was conducted in the order of 3D design, 3D output, intermediate evaluation for product, final assist device evaluation. The 3D design method was conducted in the order of prior research data survey, measurement, primary modeling, 3D printing, output evaluation, and supplementary modeling. The 3D output was the 3D printer (3DWOX 2X, Sindoh, Korea) with additive manufacturing technology and the polylactic acid (PLA) materials. At this time, the optimal strength was evaluated to infill degree of product as the 3D printing factors into 20%, 40%, 60%, and 80%. The intermediate evaluation and supplementation was measured noise in the region of interest (ROI) around the beam hardening artifact on the CT images. We used 128-channel MDCT (Discovery 75 HD, GE, USA) to scan with a slice thickness of 100 kVp, 150 mA, and 2.5 mm on the 3D printing product. We compared the surrounding noise of the final 3D printing product with the beginning of it. and then the strength of it according to the degree of infill was evaluated. As a result, the surrounding noise of the final and the early devices were measured at an average of 3.3 ± 0.5 HU and 7.1 ± 0.1 HU, respectively, which significantly reduced the noise of the final 3D printing product (p<0.001). We found that the percentage of infill according to the optimal strength was found to be 60%. Finally, development of assist devices for CT biopsy will be able to minimize artifacts and provide convenience to medical staff and patients.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.4662-4677
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• 2018

The dynamic opportunistic device-to-device (DO-D2D) network will frequently emerge in the fifth generation (5G) wireless communication due to high-density and fast-moving mobile devices. In order to improve the Quality of Experience (QoE) of users with different computing capacity devices in the DO-D2D network, in this paper, we focus on the study of how to reduce the packets retransmission delay and satisfy heterogeneous devices. To select as many devices as possible to transmit simultaneously without interference, the concurrent transmitters-selecting algorithm is firstly put forward. It jointly considers the number of packets successfully received by each device and the device's connectivity. Then, to satisfy different devices' demands while primarily ensuring the base-layer packets successfully received by all the devices, the layer-cooperation instantly decodable network coding is presented, which is used to select transmission packets combination for each transmitter. Simulation results illustrate that there is an appreciable retransmission delay gain especially in the poor channel quality network compared to the traditional base-station (BS) retransmission algorithm. In addition, our proposed algorithms perform well to satisfy the different demands of users with heterogeneous devices.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권5호
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• pp.229-235
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• 2006

High speed PC-based DIO(Digital I/O) system that consists of a master device and slave I/O devices is developed. The PCI interfaced master device controls all of serial communications, reducing the load on the CPU to a minimum. The slave device is connected from the master device and another slave device is connected to the slave device, it can repeated to maximum 64 slave devices. The slave device has 3 types I/O mode, such as 16 bits input-only, 16 bits output-only, and 8bits input-output. The master device has 2 rings which can take 64 slaves each. Therefore, total I/O points covered by the master is 2048 points. The slave features 3 types of input/output function interchangeability by DIP switch settings. Library, application, and device driver software for the DIO system that have a secure and a convenient functionality are developed.

• 한국IT서비스학회지
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• 제11권2호
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• pp.339-353
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• 2012

Mobile communication technology is advancing forward to deliver more connected devices and richer content and applications. The number of subscriptions continues to grow along with an explosive increase in the mobile data traffic demand. Thereby, it creates a significant network capacity shortage concerns for mobile network operators. In order to address this problem, it is essential to increase the network capacity at a low additional cost. The device-to-device (D2D) communication based proximity service is believed to have a promising future mobile communication technology that is capable to create new mobile service opportunities and offload traffic to the eNB. In addition, it is also required to develop new mobile communication services and its business models not only to accommodate the increasing mobile traffic demand but also to foster profitability of mobile business service providers such as the network providers, contents providers and platform providers. In this article, we first analyze current mobile business eco-system in the context of CPNT based value chain. Then, propose service development framework and business model creation methodologies for the device-to-device communication based services in the beyond LTE/LTE-Advanced systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2258-2276
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• 2019

Resource sharing is one of the main goals achieved by network virtualization technology to enhance network resource utilization and enable resource customization. Though resource sharing can improve network efficiency by accommodating various users in a network, limited infrastructure capacity is still a challenge to ultra-low latency service operators. In this paper, we propose an inter-slice resource borrowing schema based on the device-to-device (D2D) potentiality especially for ultra-low latency transmission in cellular networks. An extended and modified Kuhn-Munkres bipartite matching algorithm is developed to optimally achieve inter-slice resource borrowing. Simulation results show that, proper D2D user matching can be achieved, satisfying ultra-low latency (ULL) users' quality of service (QoS) requirements and resource utilization in various scenarios.

• 한국컴퓨터정보학회논문지
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• 제19권4호
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• pp.35-41
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• 2014

본 논문은 소프트웨어 기반의 2D BitBLT 엔진을 pSOS 운영체제에서 구현하는 것을 제안하였으며, 제안된 BitBLT엔진을 환자감시장치에서 동작을 검증하였다. 본 논문에서 제안한 방법의 검증을 위해, 환자감시장치 보드를 기반으로 하는 별도의 프로토 타입 PCB 보드를 제작하고, 동작을 검증하였다. 메인 보드는 ARM9 기반의 CPU로 설계하였으며, 하드웨어 기반의 BitBLT 모듈을 소프트웨어 기반의 모듈로 동작하면서 가중되는 CPU의 부하문제의 해결을 위해 200Mhz 프로세서 대신 400Mhz 프로세서로 변경하였다. 본 논문에서는 환자감시장치에서 GUI를 구현하는데 있어 그래픽 콘트롤러의 핵심요소 중의 하나인 2D BitBLT 모듈을 커널의 디바이스 드라이버로 구현하였다.