• 전자통신동향분석
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• 제34권6호
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• pp.61-70
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• 2019

Recently, research and development for next-generation mobile communication and short-range wireless communication has begun worldwide along with the provision of commercial services of 5G mobile communication technology. In response to this trend, the THz band has attracted considerable attention as a frequency band for transmitting 100 Gbps of large-capacity wireless data. For communication in the THz band, research and development of approaches based on photonics and electronics is being actively performed; the configurations, characteristics, and performances of these two methods for THz transmission have been seriously examined. Among them, we reviewed the technical issues in implementing THz wireless transmission technology using photonics technology. We also introduced the Electronic and Telecommunications Research Institute's (ETRI) development of photonics-based THz short-range transmission technology starting from 2019 and including some initial results. In the near future, 100 Gbps high-capacity wireless data transmission technology utilizing photonics technology is expected to be commercially available and applied to various applications, such as 3D hologram transmission, uncompressed large capacity medical data transmission, and multiple augmented reality/virtual reality (AR/VR).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1652-1654
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• 1994

The Extra-high voltage XLPE cable is characterized by low transmission loss, large capacity, and high reliability. Conventionally, for XLPE cables of l54kV and above, aluminium sheath was used to be moisture barrier (thus preventing water tree deterioration of the insulation) and to protect cable core from physical stresses. However, as transmission capacity of the cable increases, so does the cable diameter and the corresponding aluminium sheath outer diameter and thickness. As a result, eddy-current loss in the sheath is increased, limiting the maximum current capacity of the cable itself. As an alternative to aluminium sheath, we have adopted stainless steel sheath with non-magnetic properties and a large resistivity, The new XLPE cable with stainless-steel sheath (CSZV cable) has drastically reduced eddy-current loss in the sheath.

• 전기전자학회논문지
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• 제21권3호
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• pp.195-201
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• 2017

대용량 무선 전력 전송 시스템은 ESS, 배터리 장치 등의 발전을 위한 핵심 기술이다. 무선 전력 전송 장치는 현재 자기유도 및 자기공진 기술들이 주를 이루고 있으며 유선 전력 전송에 비해 전력 전송 용량이 낮고 효율이 낮은 단점이 있다. 이 논문에서는 자기 결합을 갖는 가변속 모터 시스템을 기반으로 하는 대용량 무선 전력 전송 시스템을 제안하고자 한다. 제안된 방식은 대용량 전력 전송이 가능하며, 고효율과 낮은 고장 가능성의 장점을 가지고 있으며 시뮬레이션과 실험을 통해 제안된 기법의 성능을 검증하였다.

• Structural Engineering and Mechanics
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• 제89권3호
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• pp.309-321
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• 2024

In this paper, the effect of semi-rigid connections on the stability bearing capacity of cross-bracings in steel tubular transmission towers is investigated. Herein, a prediction method based on the hybrid model which is a combination of particle swarm optimization (PSO) and backpropagation neural network (BPNN) is proposed to accurately predict the stability bearing capacity of cross-bracings with semi-rigid connections and to efficiently conduct its probabilistic assessment. Firstly, the establishment of the finite element (FE) model of cross-bracings with semi-rigid connections is developed on the basis of the development of the mechanical model. Then, a dataset of 7425 samples generated by the FE model is used to train and test the PSO-BPNN model, and the accuracy of the proposed method is evaluated. Finally, the probabilistic assessment for the stability bearing capacity of cross-bracings with semi-rigid connections is conducted based on the proposed method and the Monte Carlo simulation, in which the geometric and material properties including the outer diameter and thickness of cross-sections and the yield strength of steel are considered as random variables. The results indicate that the proposed method based on the PSO-BPNN model has high accuracy in predicting the stability bearing capacity of cross-bracings with semi-rigid connections. Meanwhile, the semi-rigid connections could enhance the stability bearing capacity of cross-bracings and the reliability of cross-bracings would significantly increase after considering semi-rigid connections.

• Journal of electromagnetic engineering and science
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• 제7권1호
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• pp.1-6
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• 2007

Recently, Mc(Multi-code) modulation/demodulation(modem) technique has been explored for high speed data transmission in wireless environment. The conventional Mc modem generates some side effects such as allocating Walsh codes, which motivates to propose a novel Mc modem method with sub-code. Our proposed system should expanded the size of sub-code to provide high-rate data transmission, which also affect adversely to the performance of the system with high PAPR(Peak to Average Power Ratio). Thus, in this paper, we propose a novel pre-coded Multi-Dimensional HCOC(High Capacity Orthogonal Code) Mc modem technique to reduce the high PAPR, which enables the performance improvement. This proposed system can be easily designed by concatenating HCOC Mc modem with the generic Mc modem. The pre-coding technique that is used in this paper is CAC(Constant Amplitude Coding), that helps the system maintain the constant transmission power and reduce the maximum transmission power.

• 대한전자공학회논문지TC
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• 제47권10호
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• pp.27-35
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• 2010

무선 패킷 망에서 무선 자원과 무선 단말의 전력을 얼마나 효율적으로 사용할 수 있는가 하는 것은 무선 패킷 망 보급을 위한 기본 해결 과제이다. 이에 단말의 전력 소모를 줄이면서 무선 망 용량 (capacity)을 증가시키는 기법으로 전송 파워 조절 기법이 주목받고 있다. 무선 패킷 망에 전송 파워 조절 기법을 적용할 때 전송 파워의 세기에 따라 공평한 전송성능을 보장하지 못하고 기아상태에 이르는 전송 불공평성 문제가 지금까지 깊이 연구되지 않고 있다. 이에 본 연구에서는 전송 파워의 세기에 따른 성능 불공평성을 경쟁자 수의 차이에 의한 불공평한 매체 접근 기회에 있음을 분석을 통해 보이고 불공평성을 해결하기 위한 간단한 물리-맥 (PHY-MAC) 계층 간 접근법을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권8호
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• pp.2923-2943
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• 2021

The double helix structure of DNA makes it diverse, stable and can store information with high density, and these characteristics are consistent with the requirements of molecular communication for transport carriers. In this paper, a specific structure of molecular communication system based on DNA length coding is proposed. Transmitter (Tx) adopts the multi-layer golden foil design to control the release of DNA molecules of different lengths accurately, and receiver (Rx) adopts an effective and sensitive design of nanopore, and the biological information can be converted to the electric signal at Rx. The effect of some key factors, e.g., the length of time slot, transmission distance, the number of releasing molecules, the priori probability, on channel capacity is demonstrated exhaustively. Moreover, we also compare the transmission capacity of DNA-based molecular communication (DNA-MC) system and concentration-based molecular communication (MC) system under the same parameter setting, and the peak value of capacity of DNA-MC system can achieve 0.08 bps, while the capacity of MC system remains 0.025 bps. The simulation results show that DNA-MC system has obvious advantages over MC system in saving molecular resources and improving transmission stability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1626-1628
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• 1998

In reccent years the large capacity underground power transmission systems have been required gradually with the increasing demand of electric power, the increasing electric power system and the environmental limitations of an overhead transmission line in the city. But it is difficult to get the space for the underground power transmission lines because of complicated distributions of underground public facilities. But as the superconducting power cables have the large power transmission capacity, the high power transmission density, and low loss characteristics in comparison with a conventional cable, the necessity for their development are increasing. In this paper, the results of the conceptual design of HTS power cable is described.

• Earthquakes and Structures
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• 제12권6호
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• pp.665-672
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• 2017

Cold-formed steel is widely used in steel structures, especially in transmission towers, because of advantages such as low weight, high strength, excellent mechanical properties, etc. However, there is not a special design code for cold-formed steel use in transmission towers in China. For this study, a total of 105 compression members were tested statically to investigate the bearing capacity of cold-formed steel members under different boundary conditions in transmission towers. The test results were compared to the results predicted by the current design codes. For deeper insight, additional coupled members were simulated using finite element analysis. An improved design method was developed based on the experimental and analytical results.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권10호
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• pp.766-770
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• 2009

인터넷 망은 대역폭이 일정치 않기 때문에 대용량 콘텐츠의 전송 QoS를 보장하기 어렵다. 현재 QoS를 보장하기 위해 사용되는 보편적인 방법은 콘텐츠 전송 네트워크인 CDN(Content Delivery Network)을 사용하는 방법이다. 본 논문에서는 기존 CDN에 적용할 수 있는 메타데이터를 이용한 콘텐츠 배포 및 관리(CDM: Content Distribution and Management using Metadata) 시스템을 제안한다. CDM 시스템은 전송률을 높이기 위하여 파일 단위로 전송되는 기존 방법 대신 병렬 전송이 가능한 세그먼트 단위 전송 방법을 지원한다. 또한, 사용자가 요구하는 내용의 콘텐츠를 우선 배포하기 위한 내용 기반 검색을 통한 배포방법을 지원한다.