• Journal of information and communication convergence engineering
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• 제8권3호
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• pp.273-276
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• 2010

Opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. The proposed protocol's simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

• Journal of information and communication convergence engineering
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• 제8권1호
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• pp.116-121
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• 2010

New teaching and studying methods using educational contents are gradually widespread with the advancement of information and communication technology. As educational contents, in this paper, we design and implement linguistic contents for studying essential expressions applied to various situations of real life. In detail, the linguistic contents are run on web environments, and have suitable animations for learning essential expressions based on several foreign languages in contextual dialogues. Also, useful functions are included in contents to reinforce what users have learned.

• Journal of Communications and Networks
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• 제8권4호
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• pp.475-479
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• 2006

In Korea, we witness vivid evidences of changing trend in communication that insist the emergence of new networking architecture. To accommodate the changing trend and to hold current strong position in global IT industry, Korea have launched broadband convergence network (BcN) initiative. BcN vision for Korea is to be the first in the world to realize converged network infrastructure and ubiquitous service environment. In this paper, we have introduced the concept and the vision of BcN with a viewpoint of a new paradigm to prepare future-proof communication environment. And then, we have disclosed BcN research and development (R&D) activities including R&D philosophy, R&D phases, and key technologies required. Also, we have discussed current development issues in three technology branches including service and control technology, unified transport technology, and next-generation access technology.

• 한국정보기술학회 영문논문지
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• 제9권1호
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• pp.11-24
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• 2019

This paper investigates the performance comparison of a Terahertz (THz) communications for a single-carrier and a multi-carrier single antenna point-to-point communication system. The multi-carrier system and single carrier system consider the orthogonal frequency division multiplexing (OFDM) and the minimum mean square error linear equalizer (MMSE-LE), respectively. We compare the frame-error-rate (FER) and throughput performance of both the systems for a THz communication environment with the carrier frequency of 300GHz and the tapped delay line (TDL) channel models described in 3GPP. It is observed from the simulation results that the OFDM systems outperform the MMSE-LE for various configurations.

• 융합정보논문지
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• 제7권3호
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• pp.117-125
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• 2017

본 연구에서는 서울시 내에 소재하고 있는 화장품 브랜드샵에 종사하고 있는 판매원들을 대상으로 하여 의사소통과 사회적 지원이 조직몰입에 미치는 영향을 실증적으로 분석하였다. 조직몰입에 미치는 영향요인으로 의사소통과 사회적 지원을 독립변수로 설정하였다. 하위변수로 의사소통 요인은 공식적인 의사소통, 상사와 의사소통, 동료와 의사소통으로 설정하였고, 사회적 지원 요인의 하위 변수는 상사의 지원과 동료의 지원으로 설정하였다. 분석 결과 공식적인 의사소통, 상사와 의사소통, 동료와 의사소통으로 설정된 의사소통 요인은 판매원들의 조직몰입에 유의한 영향요인으로 분석되었고, 상사의 지원, 동료의 지원으로 설정된 사회적 지원은 상사의 지원 요인만이 판매원들의 조직몰입에 유의한 영향요인으로 분석되었다. 그러나 동료의 지원은 판매원들의 조직몰입에 유의하지 않은 영향요인으로 분석되었다.

• 한국정보전자통신기술학회논문지
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• 제8권1호
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• pp.45-50
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• 2015

본 논문은 능동 소음 제어를 위한 적응 알고리즘들의 성능을 비교함으로써 효과적인 적응 알고리즘을 보인다. 일반적인 적응 알고리즘으로는 normalized least mean square (NLMS) 알고리즘이 있다. NLMS는 구조가 간단하고 수렴 속도가 빠르다는 장점이 있어서 널리 사용되고 있다. 하지만 상관도가 높은 신호에 대해서는 수렴 성능이 떨어지는 문제가 발생한다. 이에 수렴 성능을 개선하기 위해 affine projection (AP) 알고리즘을 사용하고 있다. 하지만 연산량의 문제로 AP 알고리즘의 사용이 제한적이다. 이러한 사실을 바탕으로 협대역 소음 제어를 위한 능동 소음 제어 시스템에서 NLMS와 AP 알고리즘을 연산량과 수렴 성능을 비교함으로써 효과적인 알고리즘을 도출하였다. 실험을 통해 NLMS와 AP 알고리즘의 소음 제어 성능이 차이가 크게 발생하지 않는 것을 확인함으로써 NLMS가 AP 알고리즘에 비해 소음 제어에 효과적임을 확인하였다.

• Journal of information and communication convergence engineering
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• 제8권4호
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• pp.387-392
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• 2010

This study focuses on improving MIMO-OFDM systems by combining a wireless communication architecture known as vertical BLAST(bell laboratories layered space-time) or V-BLAST and STTC(space time trellis coding). In this paper, the combination is done by introducing STTC in each V-BLAST layer. Moreover, this architecture uses multiple antennas that are grouped into small number of antennas which makes it less complex to decode by decoding every group. Whereas, in traditional V-BLAST, all the antennas form one group and they are decoded together at the receiver, therefore, this increases the complexity as the number of antennas is getting high. We compare the bit error rate performance of this system with MIMO-OFDM that uses convolutional coding instead of STTC. Under the same spectral efficiency, the simulation results prove that joining V-BLAST with STTC improves MIMO-OFDM systems performance.

• Current Photovoltaic Research
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• 제7권3호
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• pp.76-84
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• 2019

Silicon heterojunction solar cells (SHJ) have dominated the photovoltaic market up till now but their conversion performance is practically limited to around 26% compared with the theoretical efficiency limit of 29.4%. A silicon based multi-junction devices are expected to overcome this limitation. In this report, we briefly review the state-of-art characteristic of wide-gap materials which has played a role as top sub-cells in silicon based multi-junction solar cells. In addition, we indicate significantly practical challenges and key issues of these multi-junction combination. Finally, we focus to some characteristics of III-V/c-Si tandem configuration which are reaching highly record performance in multi-junction silicon solar cells.

• Journal of information and communication convergence engineering
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• 제8권5호
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• pp.586-590
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• 2010

Medical technology is gradually being developed by applying information technologies. Especially, RFID technology is being used for precise disease history information of patients [4]. And in case the patient is far away, the patient can be treated using network communication of the internet [5][6]. The internet makes us to treat or operate the patient without being restricted to time or space. If the above technologies are made as a system, the patient can be treated or operated without being restricted to time or space. In this paper, we present a patient treatment system has been implemented with a system using RFID and network communication of the internet [1][2][3][4]. The system is driven as follows. First, the information of patient can be checked from a remote PC, if the tag that a patient has been read through a reader. And a remote treatment is performed by controlling robot's arm with a joystick using internet network [19][20][21]. The RFID system was implemented in frequency of 125 KHz [1]. The information of patient can be checked with PDA, PC and C-LCD using Bluetooth and WLAN [7][8][9][10]. For the treatment and operation of the patient, the robot's arm has been formed using AX-12 motor, joystick and two buttons [11][12][13][14][15] [17][18].

• 한국정보전자통신기술학회논문지
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• 제15권1호
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• pp.69-75
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• 2022

지금까지 발전 설비 터빈 블레이드의 이상 탐지는 사람에 의해 진행되어왔다. 하지만 발전 설비 노후화로 인한 이상 탐지 수요 증가와 터빈 블레이드의 이상을 검사하는 검사자 간의 기량 차로 인해 발생하는 검출 결과의 상이성으로 인해, 이러한 터빈 블레이드 이상 탐지 수요 증가와 인적 요소로 인해 발생하는 오류를 줄이고 높은 신뢰성의 터빈 블레이드 이상 검출성능을 안정적으로 제공할 수 있는 기법 개발의 필요성이 지속해서 제기되어 왔다. 이번 논문에서는 최근 다양한 분야에서 인상적인 성능 향상을 달성한 깊은 신경망을 이용한 발전 설비 터빈 블레이드의 이상 탐지 기술을 제안한다. 실험 결과는 제안된 기술이 인적 요소의 개입을 최소화함과 동시에 안정적인 이상 검출성능을 달성함을 증명한다.