• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.21-31
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• 2014

In this paper, we propose VLC(visible light communication) based multi-hop multimedia data transmission system. The main contributions and features of the proposed system are as follows. First, the contribution of this research is to develope the LED communication based multi-hop transmission network system which can transmit multimedia data(audio data, video data) with long distance. Second, the developed system has the following features: In transmitter, audio data and video data are transmitted via multi-hops using two channels. The relay in audio channel receives digital audio signal by using photo diode and then transmits the signal to receiver after error checking and amplifying. The receiver receives the encoded audio data via photo diode and then converts to analog audio signal by using decoding and amplifying. The relay in video channel receives video signal by using photo diode and then amplify the video signal using OP-AMP and then transmits the signal to receiver. The receiver amplifies the received signal from photo diode and then sends it to the monitor. The performance evaluation of the proposed system is conducted in the laboratory with fluorescent light source. The results of the performance evaluation confirm that the system can provide high quality multimedia data transmission from transmiter to receiver via multi-hop relays in a long distance while we can see there are differences in the transmitted multimedia(audio and video) quality according to the used LED colors.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.305-307
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• 2012

무선 센서 네트워크에서 실시간 서비스는 중요한 이슈들 중 하나이다. 일반적으로, 기존의 연구는 이를 위해 비컨 (beacon)에 의존한다. 최근, 자원 제약적인 환경의 무선 센서 네트워크에서는 비컨으로 인한 제어 오버헤드 또한 부담이므로, 이를 극복하기 위한 비컨리스 라우팅이 제안되었다. 그러므로, 비컨리스 방안을 기반으로 한 실시간 통신이 활용 된다면 적은 에너지 소모로 환경적 제약에 유리하게 작용할 것이다. 그러나 이를 위해서는 새로운 도전에 직면한다. 전통적인 실시간 통신에서는, 요구 시간 안에 데이터를 전달하기 위해 각 노드들이 단일 홉 지연 시간을 파악하고 있어야 한다. 이 지연 시간은 비컨 메시지를 통한 이웃 노드 정보에 기반하여 파악되며, 이를 바탕으로 송신자가 적합한 다음 중계 노드를 선정한다. 그러나, 수신자 기반의 비컨리스 방안에서는 수신자가 스스로 다음 중계 노드를 결정하는 방식이기 때문에 기존의 송신자를 기준으로 한 지연 시간을 그대로 사용할 수 없다. 또한 비컨리스 라우팅을 위한 경쟁 지연 시간도 단일 홉 지연 시간에 포함되어야 한다. 따라서, 지연 시간 측정 원리가 새롭게 설계되어야 한다. 본 논문에서는 수신자 기반의 실시간 라우팅 방안을 제안한다. 제안 방안에서, 우리는 새로운 지연시간 측정 방법을 제시한다. 송신자로부터 수신자로의 단일 홉 지연 시간은 수신자에 의해 계산되어, 수신자는 실시간 제약 사항을 만족하는지 스스로가 결정할 수 있다. 시뮬레이션 결과를 통해 제안 방안이 비컨없이도 우수한 성능으로 실시간 서비스를 지원할 수 있음을 보여준다.

• Korean Journal of Plant Resources
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• v.37 no.4
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• pp.431-438
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• 2024

Hops enhance beer flavor and bitterness, acting as a preservative. In recent years, the booming trend of craft beer has prompted the introduction of foreign hop varieties for cultivation and production in South Korea. This study focuses on developing efficient in vitro culture condition of the hop (Humulus lupulus L.) variety 'Cascade' for treatments of plant growth regulators, i.e. IAA and Cytokinin. Using Auxin IAA and Cytokinin 2iP, Zeatin, BAP, and TDZ on MS medium as plant growth regulators, the experiment involved removing three nodes from the shoot apex. In vitro hop culture showed the highest shoot proliferation rate when only IAA was added, with approximately 21% higher compared to the combination with Cytokinin. Notably, IAA 0.1 mg/L + BAP 1 mg/L resulted in a superior shoot proliferation rate of around 91%. IAA 0.1 mg/L + BAP 1 mg/L was advantageous for shoot elongation. Callus induction occurred with TDZ, while control or IAA-only conditions exhibited shoot and root growth. Cytokinin addition led to callus formation and increased weight. Assessing survival and soil adaptation during in vitro hop seedling acclimatization involved maintaining near 100% humidity initially, gradually reducing it over three weeks. When transferred outdoors, 9 out of 10 seedlings acclimated successfully, confirming a 90% acclimatization rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8A
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• pp.1247-1253
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• 2000

To fully utilize the capabilities of a SONET/ADM network, traffic grooming is needed to multiplex a number of lower-rate traffic streams into a higher-rate stream, and vice versa. Although the capacity of a SONET ring network can be upgraded by operating it over multiple wavelengths, the corresponding network design may be costly if it employs a large number of ADMs. A cost-effective design attempts to minimize the total number of ADMs used in the network while carrying the offered traffic. We introduce and evaluate the performance characteristics of a new traffic-grooming approach for WDM ring networks, called multihop. The multihop implementation places an ADM at each node based on the requested traffic in the traffic-demand matrix then, it tries to groom the wavelengths which can be groomed. We select one of the nodes to be the "hub" node which has an ADM for each wavelength. The hub node, therefore, can "bridge" traffic between all of the wavelengths. The algorithm is specified and illustrated by a simple example. Our results demonstrate that it is beneficial to use a single-hop approach, but for a large grooming ratio and node number, we advocate the use of the multihop approach.e multihop approach.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.452-458
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• 2014

In Wireless Sensor Networks the Medium access control (MAC) protocol has many challenges to solve such as reducing energy consumption, supporting QoS(quality of service) fairness, and reducing delivery delay. This paper proposed a low-delay supporting MAC protocol in multi-hop Wireless Sensor Networks. The proposed protocol uses the RB(rapid beacon) frame for reducing delivery delay. The RB frame is a modified IEEE 802.15.4 beacon frame. For sender adaptive-wakeup, the RB frame includes a seed number for determining of a receiver wakeup time. And for next hop receiver adaptive-wakeup, the RB frame includes the length of remaining data packet information. Results showed that our LD-MAC protocol outperformed other protocol in terms of data packet delivery delay.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.180-187
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• 2013

In this paper, we propose a LED communication based multi-hop audio data transmission network system. The main contribution and features of the proposed system are as follows. First, the contribution of this research is to develope the LED communication based multi-hop transmission network system which can transmit audio data signal with long distance via multi-hops. Second, the developed system has the following features: In transmitter, audio data is transmitted after encoding with S/PDIF format via a general LED. The relay receives digital audio signal by using photo diode and then transmits the signal to receiver after error checking and amplifying. The receiver receives the encoded audio data via photo diode and then converts to analog audio signal by using decoding and amplifying. The performance evaluation of the proposed system is conducted in the laboratory with fluorescent light source. The results of the performance evaluation confirm that the system can provide high quality audio transmission from transmiter to receiver via multi-hop relays in a long distance while we can see there are differences in the transmitted audio quality according to the used LED colors.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.88-90
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• 2003

라우터의 If 주소검색은 라우터에 도착한 If 패킷의 목적지 주소를 이용하여 적절한 다음-홉 주소를 검색하고 결정하는 것이다. IP 주소검색은 라우터 성능의 병목지정으로써 고속 백본망에 필요한 초고속 라우터 개발에 필수적인 부분이다. 현대적인 고속 라우터는 초당 수백 안개 이상의 IP 패킷을 처리할 수 있는 능력이 필요하다. 본 논문은 보통의 Pentium CPU에서 OC-48 링크 수준의 IP 주소검색을 실시할 수 있는 빠른 검색방법을 소개한다. 본 논문에서는 데이터 압축기법으로 사용되는 RLC(Run Length Coding)와 유사한 방법을 사용하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.37-42
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• 2012

LED is just a semiconductor which can produce light. Currently, there are active research works on LED lighting technologies according to the growth of energy-saving environmental industry. Especially, LED communication is one of the active research works in these fields. In this paper, we design a LED communication-based multi-hop transmission wireless network system. The designed system consists of a transmission circuit system(transmitter) using LED and a receiving circuit system(receiver) using PD(photo detector) and OP-Amp, and relay system which can support multi-hop wireless network service with PD, OP-Amp, and LED, respectively. The experiments for the designed system are performed as follows. One computer is connected at the end of transmitter and receiver, respectively. There are two relays between transmitter and receiver, and text files are transmitted continuously by using text transmission programming. In this experiment, we test the performance with various baud rates, transmission ranges.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.853-866
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• 2008

In this paper, a multi-hop relaying transmission scheme is analyzed regarding its feasibility and potentiality in the IEEE 802.22-based cognitive radio (CR) environment. Shortly, basic design issues are addressed such as relay station (RS) deployment and a frame structure of physical channel to escape inter-hop interference. This paper mainly develops a radio resource management scheme based on spectrum sensing results aggregated from CR secondary nodes and improves the opportunistic spectrum sharing efficiency. In particular, a decision rule about a channel availability is made using a distributed sensing method. Subsequently, spectrum allocation and routing path decision procedures are proposed to establish a link from source to destination with a hop-by-hop manner. Simulation results show that the proposed multi-hop relaying scheme is substantially profitable in CR environments if the number of hops and RS deployment are designed in such a way that the spectrum sharing gain is larger than spectrum division loss which is inherently induced in multi-hop relaying systems.

• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.296-305
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• 2007

The HiLow, a hierarchical routing protocol for 6LoWPAN, needs smaller memory allocation and energy than other routing protocols. However, the HiLow has a weak point that does not provide the optimized routing path. In this paper, we propose the algorithm that can find the optimum next hop using neighboring nodes around the source node as well as hierarchical routing path information. We evaluate the performance of proposed algorithm using the computer simulation, and we can acquire results that decreases a number of hop count and transmitted message.