• Journal of the Korean Wood Science and Technology
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• 제16권1호
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• pp.45-54
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• 1988

This study was carried out to investigate the fiber length, fiber width and fiber thickness on the longitudinal direction by the parts of culm and also specific gravity in air dry, dyna.mic mechanical properties and internal frictions by the internode and the node in Phyllostachys bambusoides Phyllostachys nigra var. henonis and Phllostachys edulis which were grown in Korea. The results obtained were as follows; 1. The variations of fiber length and fiber width on the longitudinal direction had a tendency to increase slightly from the butt and then to decrease toward the top. but there was not a definite variation for fiber thickness according to the parts of culm. 2. The specific gravity in air dry of internode was increased from the butt toward the top, but the specific gravity in air dry of node was not correlations with the parts of culm. 3. Dynamic Young's modulus of internode on the longitudinal direction was increased according to the heights of culms within each species, and there were in order of P. edulis P. nigra var. henonis and P. bambusoides. 4. Correation coefficients between the specific gravity and the dynamic Young's modulus were 0.837 in P. bambusoides 0.871 in P. nigra var. henonis and 0.935 in P. edulis and there was also highly significant for dynamic Young's modulus between the specific gravities in air dry. 5. There were not correlations between the internal frictions and the parts of internode.

• 융합신호처리학회논문지
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• 제23권2호
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• pp.50-61
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• 2022

This work demonstrates the design and evaluation of Aqua-Aware, a lightweight miniaturized light emitting diode (LED) based underwater compact sensor node which is used to obtain different characteristics of the underwater environment. Two optical sensor nodes have been designed, developed, and evaluated for a short and medium link range called as Aqua-Aware short range (AASR) and Aqua-Aware medium range (AAMR), respectively. The hardware and software implementation of proposed sensor node, algorithms, and trade-offs have been discussed in this paper. The underwater environment is emulated by introducing different turbulence effects such as air bubbles, waves and turbidity in a 4-m water tank. In clear water, the Aqua-Aware achieved a data rate of 0.2 Mbps at communication link up to 2-m. The Aqua-Aware was able to achieve 0.2 Mbps in a turbid water of 64 NTU in the presence of moderate water waves and air bubbles within the communication link range of 1.7-m. We have evaluated the luminous intensity, packet success rate and bit error rate performance of the proposed system obtained by varying the various medium characteristics.

• 설비공학논문집
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• 제11권3호
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• pp.281-291
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• 1999

A computer code based on a node equation method has been developed for the analysis of pipe network. Both data structure and object-oriented programming technique are used for pipe and node modelling, in which simplification process is applied to complicated and large pipe network. The semi-direct solver, ILU-CGS, improves greatly both the accuracy and the rate of convergence. The computational result of high-pressure pipe network of city gas in Taegu shows the good agreement with the real data.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.683-688
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• 2011

The wireless sensor network (WSN) is well known for an enabling technology for the ubiquitous environment such as real-time surveillance system, habitat monitoring, home automation and healthcare applications. However, the WSN featuring wireless communication through air, a resource constraints device and irregular network topology, is threatened by malicious nodes such as eavesdropping, forgery, illegal modification or denial of services. For this reason, security in the WSN is key factor for utilizing the sensor network into the commercial way. There is a series of symmetric cryptography proposed by laboratory or industry for a long time. Among of them, recently proposed HUMMINGBIRD algorithm, motivated by the design of the well-known Enigma machine, is much more suitable to resource constrained devices, including smart card, sensor node and RFID tags in terms of computational complexity and block size. It also provides resistance to the most common attacks such as linear and differential cryptanalysis. In this paper, we implements ultra-lightweight cryptography, HUMMINGBIRD algorithm into the resource constrained device, sensor node as a perfectly customized design of sensor node.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권10호
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• pp.3439-3457
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• 2014

Clustering is an effective method for improving the performance of large scale mobile ad hoc networks. However, when the moving speed is very fast, the topology changes quickly, which leads to frequent cluster topology updates. The drastically increasing control overheads severely threaten the throughput of the network. SCBCS (Signal Characteristic Based Cluster Scheme) is proposed as a method to potentially reduce the control overheads caused by cluster formation and maintenance in aeronautical ad hoc networks. Each node periodically broadcasts Hello packets. The Hello packets can be replaced by data packets, which preserve bandwidth. The characteristics of the received packets, such as the Doppler shift and the power of two successive Hello packets, help to calculate the relative speed and direction of motion. Then, the link connection lifetime is estimated by the relative speed and direction of motion. In the clustering formation procedure, the node with the longest estimated link connection time to its one-hop neighbors is chosen as the cluster head. In the cluster maintenance procedure, re-affiliation and re-clustering schemes are designed to keep the clusters more stable. The re-clustering phenomenon is reduced by limiting the ripple effect. Simulations have shown that SCBCS prolongs the link connection lifetime and the cluster lifetime, which can reduce the topology update overheads in highly dynamic aeronautical ad hoc networks.

• 스마트미디어저널
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• 제9권3호
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• pp.71-79
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• 2020

이동통신망은 통화, 메시지, 데이터 전송 등의 서비스를 위하여 많은 사용자들이 전 세계적으로 사용하고 있는 네트워크이다. 이동통신망은 긴급재난망으로도 사용되고 있는 국가적으로 중요한 공공자산이며 이동통신망에서 사이버 공격이나 통신 방해를 이용한 서비스거부공격이 발생할 경우 다양한 피해를 초래할 수 있다. 그러므로 이러한 이동통신망에 대한 안전성 검증이 필수적이나 정해진 몇몇 이동통신사업자들이 망을 구축하여 폐쇄적으로 서비스하고 있고 망의 안전성 검증을 위한 테스트 망이 따로 존재하지 않아 실제로 이동통신망의 코어네트워크를 분석하기는 쉽지 않다. 따라서 본 논문에서는 3GPP 표준을 기반으로 구현하여 오픈소스로 제공되는 OpenAirInterface를 이용하여 가상의 이동통신망을 구축하고 이를 기반으로 코어네트워크 구조와 프로토콜을 분석한다. 특히 단말기에서 전송되는 메시지가 코어네트워크에 미치는 영향을 분석하기 위하여 기지국인 eNodeB와 단말기를 관리하는 MME 사이의 인터페이스인 S1-MME에서의 S1AP 프로토콜 메시지를 분석하여 보안 위협의 실현 가능성을 확인한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권8호
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• pp.3862-3888
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• 2017

In high diversity node situation, single-channel MAC protocols suffer from many collisions. To solve this problem, the research of multichannel MAC protocol has become a hotspot. And the cyclic quorum-based multichannel (CQM) MAC protocol outperformed others owing to its high frequency utilization. In addition, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQM MAC protocol, a Markov chain model, which combines the channel hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The metrics (throughput and average packet transmission delay) are calculated in performance analysis, with respect to node number, packet rate, channel slot length and channel number. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm (BSA). Finally, the Markov chain model and saturation bound are verified by Qualnet platform. And the simulation results show that the analytic and simulation results match very well.

• Transactions on Electrical and Electronic Materials
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• 제12권4호
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• pp.131-134
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• 2011

Back-end-of-line using ultra low-k (ULK; k < 2.5) has been required to reduce resistive capacitance beyond 45 nmtechnologies, because micro-processing units need higher speed and density. There are two strategies to manufacture ULK inter-layer dielectric (ILD) materials using an air-gap (k = 1). The former ULK and calcinations of ILD degrade the mechanical strength and induce a high cost due to the complication of following process, such as chemical mechanical polishing and deposition of the barrier metal. In contrast, the air-gap based low-k ILD with a relatively higher density has been researched on the trench-type with activity, but it has limited application to high density devices due to its high air-gap into the next metal layer. The height of air-gap into the next metal layer was reduced by changing to the via-typed air-gap, up to about 50% compared to that of the trench-typed air-gap. The controllable ULK was easily fabricated using the via-typed air-gap. It is thought that the via-type air-gap made the better design margin like via-patterning in the area with the dense and narrow lines.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.627-628
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• 2008

This paper proposes an indoor air Quality monitoring system for measuring various indoor air qualities using IEEE 802.15.4 based wireless sensor network. For indoor air quality monitoring, sensor nodes include carbon monoxide sensor and dust sensor were used. The wireless network by deployed sensor nodes has limited energy, computing, communication capabilities and memory sizes. In this paper, the query process in indoor air quality monitoring was designed to improve the limited sensor node resources such as battery consumption and networking.

• 대한안전경영과학회지
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• 제8권6호
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• pp.91-108
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• 2006

RFID/USN is important infrastructure of the ubiquitous society. And so, It is various and practical research is attempted. These two base technology have physical characteristic and complement relationship. Like this relationship is applied Following example that is system research which manages warehouse stocks and conditions. First, We adhere RFID Tag at the Pallet of the warehouse and do identification goods. And then, It grasps the environment state information of stocks with sensor module which has Zigbee wireless communication function. From like this process RFID Tag information and jop-control command of sensor node also it is exposed to air. Therefore, We control sensor node in USN/RFID environment through the mobile device. And system design for the security Apply of the process is main purpose of this paper's. We propose the condition and function of the mobile device to the secondary. And We define the relation of the sensor node with RFID to be arranged to a warehouse. Finally, This paper is designed to find a trade-off of the following viewpoints. First, We offer suitable sensor-control information to a actual manager. Second, We offer RFID tag security approach to control the action of the sensor. Third, It increases the survivability of sensor node form.