• 디지털콘텐츠학회 논문지
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• 제6권1호
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• pp.7-12
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• 2005

논문은 IEEE 표준인 SCI(Scalable Coherent Interface)에 근거한 degree 2의 ICR(Interleaved Cyclic Ring) 네트워크의 신뢰도를 연구하였고 대표적인 링 네트워크들과 비교하였다. ICR 네트워크의 신뢰도 연구에 있어서 두 노드가 동시에 통신 할 수 있는 신뢰도를 계산하였다. ICR 네트워크의 신뢰도 연구에서 실패율(failure rate)의 변화에 신뢰도의 반응을 연구하였고 적은 노드에 대하여 정확한 신뢰도를 구하고 노드 수가 증가한 경우에는 최대 최소 경계를 계산하여 평균치 일반식을 구하였다. ICR 네트워크의 사이클의 변화에 따라 ICR 네트워크의 신뢰도를 다른 링 네트워크와 비교하였다.

• 한국통신학회논문지
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• 제34권4A호
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• pp.309-315
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• 2009

무선 Ad-hoc 네트워크는 이동 노드로 구성되는 동적 네트워크이다. 일반적으로 Ad-hoc 네트워크에서 노드는 랩탑, PDA, 모바일 폰 등과 같은 장치로 블루투스나 IEEE 802.11(위피) 네트워크 인터페이스의 특징을 가지고 분산방식으로 통신을 한다. 이러한 Ad-hoc 네트워크의 특성에 기인한 이동성은 라우팅 프로토콜 디자인에 중요한 특징적 요소가 된다. 본 논문에서는 토폴로지 변화에 잘 적응하는 향상된 경로 관리 기법을 제안한다. 제안된 알고리즘에 주된 특징은 경로 실패를 방지하기 위해서 링크 단절 전에 다음-홉 노드를 대체 이웃 노드에 스위칭 하는 방식이다. NS2를 이용한 무선 Ad-hoc 네트워크의 다양한 환경에서 시뮬레이션을 수행한 결과 제안된 알고리즘 성능이 기존의 AODV 프로토콜에 비교하여 향상되었음을 보인다.

• ETRI Journal
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• 제36권1호
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• pp.1-11
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• 2014

In this paper, we propose a distributed synchronization algorithm for wireless mesh networks based on orthogonal frequency division multiple access. For time and frequency synchronization, a node requests its neighbor nodes for a change of fast Fourier transform starting points, transmission times, and carrier frequencies needed for synchronization. The node also updates its own time and frequency elements through simple formulas based on request messages received from neighbor nodes using a guard interval and a cyclic prefix. This process with the cooperation of neighbor nodes leads to a gradual synchronization of all nodes in the network. Through a performance comparison with a conventional scheme, we obtain simulation results indicating that the proposed scheme outperforms the conventional scheme in random topologies and a grid topology.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.88-94
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• 1996

The dependence of the node size in the condensation heat transfer coefficient for an inclined surface is eliminated and two correlations applicable for laminar and turbulent regimes are implemented in RELAP5/MOD3.1. The newly implemented correlations are used according to their applicable ranges of the film Reynolds numbers Reps which are calculated recursively to track the condensate film thickness along the condensation length. The modified version is compared with the original one through comparison with an analytical solution and the simulation of the Secondary Condensers (SC). It turns out that the simulation results by this modified version are independent of the node size and are better agreement with the analytical solution than those by the original one.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.341-344
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• 2005

Mobile IPv6(MIPv6) allows a Mobile Node to talk directly to its peers while retaining the ability to move around and change the currently used IP address. One of the major issues regarding the basic Mobile IPv6 protocol is related to the handover management of a mobile node. This paper proposes efficient approach for adaptation of MIPv6 sing context information in roaming environments. To investigate on a efficient and secure handover procedure, proposed approach method will give us the following advantages: (l)the intention of context is to reduce latency, packet losses and avoid re-initiation of signaling to and from mobile nodes,(2) FMIPv6 aims to reduce handover latency due to IP protocol operations as small as possible in comparison to the inevitable link switching latency.

• Journal of Chest Surgery
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• 제29권1호
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• pp.52-58
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• 1996

Sixty six patients who were operated as lung cancer during the period from Mar. 1991 to Sep. 1993 at the department of Thoracic and cardiovascular surgery, were reviewed retrospectively and the accuracy of regional lymph node in preoperative CT were compared with histopathologlc report obtained from operation. The age ranged from 30 to 72 years old (mean age : 56.5), and 51 patients were male and 15 patients were female. The author analysed the true positive, true negative, false positive and false negative and sensitivity, specificity, positive predictive index, negative predictive index and accuracy of each nodes. The result is that there were differences between seven nodal groups in specificity, sensitivity, positive predictive Index, negative predictive index and accuracy. The range of each nodal group is from 81.7 to 98.3% The nodes of the most poor accuracy are aortopulmonary area and hilar area.

• Structural Engineering and Mechanics
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• 제38권4호
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• pp.417-428
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• 2011

This paper presents recovering of missing vibration data of a bridge transmitted from wireless sensors. Kalman filter algorithm is adopted to reconstruct the missing data analytically. Validity of the analytical approach is examined through a field experiment of a bridge. Observations demonstrate that, even a part of recovered acceleration responses is underestimated in comparison with those responses taken from cabled sensors, dominant frequencies taken from the reconstructed data are comparable with those from cabled sensors.

• Structural Engineering and Mechanics
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• 제4권4호
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• pp.437-450
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• 1996

A study on the behaviour of fibre reinforced concrete deep beams with and without web openings is carried out using nonlinear finite element analysis. Eight node isoparametric plane stress elements are employed to model the fibre reinforced concrete materials. Steel bars are treated using a compatible three node truss elements. The constitutive equations for fibre reinforced concrete materials take into account the softening effect of co-existing shear strains. Element stiffness at each step is formulated based on the tangent modulus at the current level of principal strains. Transformation between principal directions and global coordinate system is imposed. Comparison of analytical results with experimental values indicates reasonably good agreement. The proposed numerical model can be used to study the behaviour of this composite structures of practically any geometries.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.290-295
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• 2003

Among the thermal analysis methods for Multi-Layer Insulation(MLI), effective emittance, diffusion MLI node and arithmetic MLI node methods are compared. The methods have been applied to the aluminum panel under the low earth orbit environment. TRASYS program is used for geometrical math modeling and SINDA program for thermal math modeling and temperature calculation. Test cases are selected according to MLI area on the panel. Temperature results are calculated and compared under the ratio of absorptivity and emissivity.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.304-308
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• 2006

The focus of this study is modeling technique for a bellows in vehicle exhaust system. Bellows was developed using tile finite element model by replacing with the equivalent beam. The equivalent beam model were studied in detail. Non-structural node in the cross section of original model is given to expressing their motion. Equivalent mass matrix and stiffness matrix calculated using Guyan reduction method. Material Properties of beam was obtained from the direct comparison between equivalent model and that of Timoshenko beam model. The calculated natural frequencies and mode shape are compared with the reference results and coincided well. The results were compared with the confirmed results, which were in good agreement.