• 대한두경부종양학회지
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• 제26권1호
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• pp.3-8
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• 2010

Background : Though papillary microcarcinoma(PMC) of thyroid gland is known to have very favorable long-term prognosis, the recurrence in the neck and distant metastasis have been often reported. The predictive factors of node metastasis and tumor recurrence in clinical course were investigated to define surgical decision or guidelines in surgery of papillary microcarcinoma. Methods : The authors conducted a retrospective analysis of 216 patients of PMC treated with surgery at Department of Surgery, Busan Paik Hospital for the period from 1997 to 2007. Of these patients, 58 cases showing cervical lymph node metastasis at initial surgery were studied. Results : In overall 216 patients, the sex ratio of male to female was 1 : 9.3(male 21, female 195 cases), the mean age at the time of diagnosis was 44.7 years and the median tumor size was 6.61mm. Neck lymph node metastasis was found in 58 patients(26.9%), thyroid capsular invasion was 56 cases(25.9%), multifocality and bilaterality were found in 32(14.8%) and 29 cases(13.4%), respectively. Through statistical analysis, sex, capsular invasion, ETE, and tumor size(>5mm) were considered to be predictive factors of cervical lymph nodes metastasis. Of them, capsular invasion was the most predictive indicator of cervical lymph node metastasis on multivariate analysis. Nodal recurrence was observed in 6 of 58 patients of node positive at initial surgery. Conclusion : The cervical lymph node metastasis is known to be a risk factor of prognosis in PMC of thyroid gland. The results of this study showed four statistically significant independent predictive factors of cervical lymph node metastasis in PMC : capsular invasion, tumor size(>5mm), ETE, and sex. On multivariate analysis, capsular invasion was a great influencing factor in prediction of lymph node metastasis. Basically, patients who has predictive factors of cervical lymph node metastasis should have a thorough investigation, and close surveillance for nodal status is required in follow-up.

• 한국지능시스템학회논문지
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• 제8권4호
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• pp.1-7
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• 1998

This paper describes a meshless of element-free method based on fuzzy knowledge processing. To efficiently simulate complicated physical phenomena with dynmics and non-linear ploblem using computational mechanics, special method is required such as parallel processing or adaptive analysis techniques. However, the conventional finite element method is too complicated to be employed in the above cases. In order to reduce the above complexity of the conventional finite element analysis systms, the so called meshles finite elements as an input information have been stuided. Node is generated if its distance form existing node points is similar to the node spacing fuction at the point. The node spacing function is well controlled by the fuzzy knowledge processing Practical performances of the present system are demonstrated through several three-dimensional(3D) problems.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.487-494
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• 2003

Recently it is used seismic analysis like single mode spectrum analysis, multi mode spectrum analysis and time history analysis in Korea. Because bridges are not special form of them but regular and simple form of them in our country, we must develope seismic analysis program of bridge based on single nude spectrum analysis. The program developed by this study reduces a Quantity and a time of calculation compared to SAP90 and gives accurate answers without errors. In the case of commercial program if we look for seismic load(P/sub e/(x)), we must increase the number of node and the larger the number of node the more a quantity and a time of calculation. But this program is exactly solved with basic node compared to commercial program.

• 농촌계획
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• 제23권1호
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• pp.1-10
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• 2017

네트워크를 분석하는 방법인 stochastic 기반의 community bridge node finder는 네트워크 구조의 일부 정보만을 이용하여 중심지 및 확산 경로의 유추가 가능하다. 그러나, heterogeneity 네트워크에 적용하기 어려운 단점을 보유하고 있어, 본 연구에서는 이를 개선하고자 하였다. heterogeneity 네트워크에 적용할 수 있는 community bridge node finder 방법을 개발하기 위해 네트워크의 modularity를 계측하는 방법을 적용하였으며, 개선된 방법을 통해 community bridge node를 정량적으로 평가할 수 있어 heterogeneity 네트워크의 분석이 가능하였다. 농촌계획분야 정보의 경우, 대부분 자료의 불확실성이 존재하며 무결성이 떨어지는 특성을 가지고 있는 바 본 연구에서 적용한 전염병 확산 예측 뿐만 아니라 개선된 방법을 활용할 경우 주산지 정비 거점 분석 등 다양한 형태로 이용될 수 있을 것으로 기대된다.

• 대한임베디드공학회논문지
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• 제1권2호
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• pp.37-42
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• 2006

In this paper, we study a problem of providing reliable data transmission in wireless sensor network(WSN). A system with forward error correction9FEC) can provide an objective reliability while using less transmission power than a system without FEC. We propose the use of LDPC codes of various code rate (0.53, 0.81, 0.91) of FEC for WSN. Node-node-node interference is considered in the simulation in addition to AWGN in the channel. It is shown that the rate of 0.91 LDPC coded system obtained 7dB gain in signal to noise ratio over a system without FEC.

• Journal of Gastric Cancer
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• 제2권1호
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• pp.5-11
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• 2002

Purpose: The purpose of this study is to identify immunohistochemical evidence of lymph-node micrometastasis in histologic node-negative gastric cancer patients and to evaluate the prognostic significance of lymph-node micrometastasis.Materials and Methods: A retrospective study of 50 gastric cancer patients who underwent curative resections from October 1990 to November 1994 was performed. Two consecutive sections were prepared: one for ordinary hematoxylin and eosin staining, and the other for immunohistochemical staining with Pan cytokeratin antibody (Novocastra, UK). In the univariate analysis, the survival rate was calculated using the Life Table Method, and the multivariate analysis was determined using a Cox Proportional HazardsModel. The statistical analyses of the relationships between the clinicopathologic factors and micrometastases were performed by using a Chi-square test. Results: Of 2522 harvested lymph nodes, 81 ($4.1\%$) nodes and 19 ($38\%$) of 50 patients were identified as having lymphnode micrometastases by using immunohistochemical staining for cytokeratin. The incidence of lymph-node micrometastases was significantly higher in diffuse type carcinomas ($54\%$, P=0.024) and in patients with serosal invasion ($52.2\%$, P=0.05). For patients with lymph-node micrometastases (n=19), the 5-year survival rate was significantly decreased ($73.7\%$, P=0.015). The Lauren's classirication (P=0.021) and the depth of invasion (P=0.035) were shown by multivariate analysis to have a significant relationship with the presence of micrometastases. Multivariate analysis revealed that lymph-node micrometastasis was independently correlated with survival in histologic node-negative gastic cancer patients. Conclusion: The presence of cytokeratin detected lymphnode micrometastases correlates with the worse prognosis for patients with histologic node-negative gastric cancer.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.608-619
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• 2018

As distributed generation (DG) is connected to grid, there is new node-type occurring in distribution network. An efficient algorithm is proposed in this paper to calculate power flow for weakly meshed distribution network with DGs in different load models. The algorithm respectively establishes mathematical models focusing on the wind power, photovoltaic cell, fuel cell, and gas turbine, wherein the different DGs are respectively equivalent to PQ, PI, PQ (V) and PV node-type. When dealing with PV node, the algorithm adopts reactive power compensation device to correct power, and the reactive power allocation principle is proposed to determine reactive power initial value to improve convergence of the algorithm. In addition, when dealing with the weakly meshed network, the proposed algorithm, which builds path matrix based on loop-analysis and establishes incident matrix of node voltage and injection current, possesses good convergence and strong ability to process the loops. The simulation results in IEEE33 and PG&G69 node distribution networks show that with increase of the number of loops, the algorithm's iteration times will decrease, and its convergence performance is stronger. Clearly, it can be effectively used to solve the problem of power flow calculation for weakly meshed distribution network containing different DGs.

• 대한전자공학회논문지TC
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• 제37권2호
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• pp.7-16
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• 2000

본 논문에서는 p-persistent CSMA 방식의 IEEE 802.11 MAC 계층 프로토콜을 모델링 하였다. 그리고 renewal 이론을 적용하여 수학적으로 분석한 Basic CSMA/CA 프로토콜, CTS/RTS 프로토콜 그리고 은닉 노드를 고려한 Basic CSMA/CA 등의 성능분석모델을 제안하였다. 제안한 분석 모델을 이용하여 throughput을 구한 결과, active 노드 수가 적거나 패킷의 길이가 짧을 때는 Basic CSMA/CA 프로토콜 방식이, active 노드 수가 많거나 패킷의 길이가 길 때는 CTS/RTS 프로토콜 방식이 우수하였다. 또한 active 노드 수가 적은 경우가 많은 경우 보다 은닉 노드의 영향을 적게 받았다.

• Journal of Communications and Networks
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• 제5권3호
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• pp.249-257
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• 2003

Ring networks are very commonly exploited among local area and metropolitan area networks (LAN/MAN), whereas cells or small fixed-size packets are widely used in synchronized ring networks. In this paper, we present an analytical method for evaluating the delay-throughput performance of a MAC protocol with multiple self-tokens in a slotted ring network under uniform traffic. In our analysis, we introduce the stationary probability, which indicates the number of packets in a node. Also, it is assumed that each node has a sufficiently large amount of self-tokens, and a slotted ring has the symmetry. The analytical results with respect to delay-throughput performance have similar values to computer simulated ones. Furthermore, in order to achieve fair access under non-uniform traffic, we propose an adaptive MAC protocol, where the number of self-tokens in a node dynamically varies, based on the number of packets transmitted within a specified period. In the proposed protocol, when the number of packets transmitted by a node within a specified period is larger than a specified threshold, the node decreases the number of self-tokens in a per-node distributed method. That results in creating free slots in the ring, thus all nodes can obtain an equal opportunity to transmit into the ring. Performance results obtained by computer simulation show that our proposed protocol can maintain throughput fairness under non-uniform traffic.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.733-736
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• 2013

유비쿼터스 컴퓨팅의 핵심 기술인 센서 네트워크 기술이 각광을 받으면서 다양한 종류의 센서 노드로 구성된 센서 네트워크에 대한 연구가 활발히 진행되고 있다. 센서 네트워크 어플리케이션들의 주요 트래픽 패턴은 몇몇의 센서 노드들로부터 싱크 노드로 패킷을 전송하는 타입의 단일 방향성 데이터 수집형태로 구성되어있으며 소스 노드, 중간 노드, 싱크 노드에 이르기 까지 각각 자신의 상위 노드를 곧 바로 깨움으로써 지연의 감소와 에너지 효율성을 이끌어냈다. 본 논문에서는 센서 노드의 지연 감소를 위해 2계층 클러스터 구조를 제시하고 이에 기존에 사용한 라우팅 프로토콜을 네트워크 시뮬레이션을 통해 비교 분석하였다.