• 한국정보통신학회논문지
• /
• 제17권9호
• /
• pp.2174-2182
• /
• 2013

본 논문에서는 LED 기반 VLC 통신시스템의 기술동향 및 국제표준인 IEEE 802.15.7의 PHY 기술을 분석하였다. 또한, PHY I mode의 세부기술을 분석하고 RS 부호 및 블록 인터리버를 설계함으로써 시스템의 복잡도 분석 및 가시광 무선채널 환경에서의 수신 성능을 분석하였다. 결과에 의하면, Single mode로 운영되는 PHY I의 경우, 짧은 메시지 전송이라는 환경에 비해 시스템 설계의 복잡도가 크다는 것을 확인할 수 있었고, 다중경로 가시광 채널환경에서는 1.5dB의 수신 SNR이 추가적으로 요구됨을 확인할 수 있었다.

• Journal of Electrical Engineering and Technology
• /
• 제10권4호
• /
• pp.1752-1758
• /
• 2015

This paper presents partial discharge localization in stator winding of generators using multi-conductor transmission line (MTL) and RLC ladder network models. The high-voltage (HV) winding of a 6kV/250kW generator has been modeled by MATLAB software. The simulation results of the MTL and the RLC ladder network models have been evaluated with the measurements results in the frequency domain by applying of the Pearson’s correlation coefficients. Two PD generated calibrator signals in kHz and MHz frequency range were injected into different points of generator winding and the signals simulated/measured at the both ends of the winding. For partial discharge localization in stator winding of generators is necessary to calculate the frequency spectrum of the PD current signals and then estimate the poles of the system from the calculated frequency spectrum. Finally, the location of PD can be estimated. This theory applied for the above generator and the simulation/measured results show the good correlation for PD Location for RLC ladder network and MTL models in the frequency range of kHz (10kHz<f<1MHz) and MHz (1MHz<f<5MHz) respectively.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
• /
• pp.189-191
• /
• 2005

In the past, dramatic economical development of Korea could be achieved by well-organized 154kV power system network. Electric power Is a key Industry for the nation and industrial development. Nowadays we operates 345kV Power system with based transmission network and also we are operating 765kV power system to supply to the capital region. Currently developing countries in Southeast Asia are requiring the electric power technology to Korea so that they can acquire the source of the development-power system network. Therefore, it Is important to design transmission line and substation with appropriate methods. In this paper, a calculation and calculating process of shielding range using shield wires in Myanmar 500kV substation are reviewed according to the Myanmar 500kV power system project performed by the overseas projects section of the Korea Electric Power Corporation.

• 한국통신학회논문지
• /
• 제25권1B호
• /
• pp.175-182
• /
• 2000

적외선을 이용한 수/발광 다이오드에 집적소자를 혼합한 Hybrid형 단거리 광무선 통신용 원칩모듈을 개발하였다. 발광다이오드는 850nm 의 적외선파장을 30$^{\circ}$지향각을 갖는 AlGaAs계 고속신호용으로서 전파지연이 60 ns 이며, PIN 포토다이오드는 Si계 반도체 수광소자로써 450-1050nm의 파장대에서 수광 흡수율이 양호하고 필터겸용 블록 에포시렌즈를 750nm 파장 저역대를 여과시켰다. 데이터 전송속도는 115.2 kbps이며 IrDA1.0 SIR 표준조건에서 동작이 양호함을 확인하였다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2005년도 추계학술대회 논문집
• /
• pp.193-197
• /
• 2005

Influences of microstructure on high-cycle fatigue (HCF) limit of high carbon $(>0.7wt.\;\%)$ steel filaments used for tires have been investigated. A series of the fatigue tests was carried out depending on carbon content by using Hunter-type tester at a frequency of 60 Hz at a tension/compression stress of 900 to 1500 MPa. Microstructural changes of the filaments were identified in the lateral direction by using transmission electron microscopy (TEM). It was found that the mechanical properties, such as fatigue limit and tensile strength, were improved with increasing carbon content, which was mainly attributed to decreased lamellar spacing and cementite thickness. However, the fatigue ratio, which is defined as the ratio of the fatigue limit to the tensile strength, was reduced in a higher carbon range of 0.8 to $0.9\;wt.\%$, while the fatigue ratio was nearly constant in a lower carbon range of 0.7 to $0.8\;wt.\%$. Overall mechanical properties of the filaments, depending on carbon content, have been discussed in terms of the microstructural parameter change of lamellar spacing and cementite thickness. In addition, the variation of cementite morphology on the fatigue crack propagation of high carbon $(0.9wt.\;\%)$ filaments will be discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제13권10호
• /
• pp.5035-5057
• /
• 2019

Advancements in nanotechnology and novel nano materials in the past decade have provided a set of tools that can be used to design and manufacture integrated nano devices, which are capable of performing sensing, computing, data storing and actuation. In this paper, we have proposed cooperative nano communication using Power Switching Relay (PSR) Wireless Power Transfer (WPT) protocol and Time Switching Relay (TSR) WPT protocol over independent identically distributed (i.i.d.) Rayleigh fading channels in the Terahertz (THz) Gap frequency band to increase the range of transmission. Outage Probability (OP) performances for the proposed cooperative nano communication networks have been evaluated for the following scenarios: A) A single decode-and-forward (DF) relay for PSR protocol and TSR protocol, B) DF multi-relay network with best relay selection (BRS) for PSR protocol and TSR protocol, and C) DF multi-relay network with multiple DF hops with BRS for PSR protocol and TSR protocol. The results have shown that the transmission distance can be improved significantly by employing DF relays with WPT. They have also shown that by increasing the number of hops in a relay the OP performance is only marginally degraded. The analytical results have been verified by Monte-Carlo simulations.

• 한국통신학회논문지
• /
• 제21권2호
• /
• pp.326-332
• /
• 1996

본 논문은 음량정격의 평가척도를 적용하여 디지털 음성통신 서비스 단말기인 디지털 전화기의 통화품질을 연구한 것으로서 디지털 전화기의 송화음량정격을 설계하는 방법을 제시하고 바람직한 전송특성의 범위를 제시하였다. 송화음량정격을 설계하기 위해서 디지털 전화기의 코덱 입력레벨을 최적으로 규정하기 위한 주관평가 실험이 수행되었다. 실험 결과로 부터 70dBspl의 청취레벨에서 -12dB~-18dB 사이의 코덱 입력레벨이 코덱의 양자화 잡음이나 왜곡을 유발하지 않는 것으로 나타났으며, 최적의 코덱 입력레벨은 -15dB임을 알 수 있었다. 이 결과를 디지털 전화기의 송화감도에 적용하여 디지털 전화기의 바람직한 통화품질을 설정하기 위한 송화음량정격의 범위는 6.2dB 이상으로 설계되어야 함을 확인하였다.

• Journal of Plant Biology
• /
• 제6권2호
• /
• pp.9-21
• /
• 1963

A mosaic diseased radish collected from the suburb of Seoul, in November, 1961 was used for studing the host range, physical properteis, purificaitiion, insect transmission, and electron microscopy. A Japanese strain of radish mosaic(RPV) was also used with Korean strain of radish mosaic (KRMV) for a comparative study. The two viruses, KRMA and RPV, were identified by the difference in host range, insect transmission and electron microscopy. The KRMA was severely infective on tobacco and Nicotiana glutinosa, while on Gomphrena globsa was immune to the virus. RPV produces necrotic local lesions on Gomphrena globosa but did not infect tobacco and N. glutinosa. Among varieties of radish, Seoul, Akamaroo, Akanagea, Koong-Joong showed more severe symptoms than Simoo, Minong, Paek-soo, which appeared to be fainly resistant. In a number of tests, it was found that the virus KRMA retained its infectivity until to a dilution of 1:2,000, heating at $58^{\circ}$ for 10 minutes, adn aging in vitro for 7 days at room temperature. The RPV was not inactivated until it was diluted to 1:2,000, heated to $56^{\circ}$, and aged for 6 days. The KRMV was readily transmitted by the aphid(Myzus persicae Sulz). The virus RPV was not transmitted by the aphid in a number of tests. Partialy purified viruses using ammonium acetate buffer, salting-out by ammonium sulfate and centrifugation of high and low speed were highly infective. Electron micrographs showed that the KRMV paticles are of spherical particles whereas the RPV particles are rod-shaped.

• Journal of Plant Biology
• /
• 제6권2호
• /
• pp.7-7
• /
• 1963

A mosaic diseased radish collected from the suburb of Seoul, in November, 1961 was used for studing the host range, physical properteis, purificaitiion, insect transmission, and electron microscopy. A Japanese strain of radish mosaic(RPV) was also used with Korean strain of radish mosaic (KRMV) for a comparative study. The two viruses, KRMA and RPV, were identified by the difference in host range, insect transmission and electron microscopy. The KRMA was severely infective on tobacco and Nicotiana glutinosa, while on Gomphrena globsa was immune to the virus. RPV produces necrotic local lesions on Gomphrena globosa but did not infect tobacco and N. glutinosa. Among varieties of radish, Seoul, Akamaroo, Akanagea, Koong-Joong showed more severe symptoms than Simoo, Minong, Paek-soo, which appeared to be fainly resistant. In a number of tests, it was found that the virus KRMA retained its infectivity until to a dilution of 1:2,000, heating at $58^{\circ}$ for 10 minutes, adn aging in vitro for 7 days at room temperature. The RPV was not inactivated until it was diluted to 1:2,000, heated to $56^{\circ}$, and aged for 6 days. The KRMV was readily transmitted by the aphid(Myzus persicae Sulz). The virus RPV was not transmitted by the aphid in a number of tests. Partialy purified viruses using ammonium acetate buffer, salting-out by ammonium sulfate and centrifugation of high and low speed were highly infective. Electron micrographs showed that the KRMV paticles are of spherical particles whereas the RPV particles are rod-shaped.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집B
• /
• pp.618-623
• /
• 2001

In a practical vibration isolation system, vibration is transmitted from the source to the receiver through several paths such as more than one inter-connected point and multi-degree of freedom at each connection point. Therefore, the major path investigation for vibration transmission among them is often required in a point of view of isolation. For the path analysis of multi-dimensional vibration isolation system, it is useful to employ the concept of vibration power in high frequency range where radiation of noise from the receiver structure is concerned. The idea is simple to understand and formulate but rather complicated to apply in practice. For an accurate estimation of power flow especially over a high frequency range, it is well known in theory that rotational motions should be taken into consideration together with translational motions at inter-connected points. In reality, however, power transmissions related to rotational terms are often neglected mainly due to difficulties in the instrumentation. In this paper, necessary formula and measurable mechanical quantities for vibration power analysis will be reviewed and experimental results with rotational terms included for compressor system in a commercial air conditioner will be shown.