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안창욱,허훈,조용관,한상욱 대한위암학회 2013 Journal of gastric cancer Vol.13 No.1
Purpose: The intracorporeal reconstruction after laparoscopic gastrectomy can minimize postoperative pain, and give better cosmetic effect,while it may have technical difficulties and require the learning curve. This study aimed to analyze the surgical outcome of intracorporeal reconstruction according to the surgeon’s experience comparing with extracorporeal procedure. Materials and Methods: From January 2009 to September 2011, intracorporeal reconstruction in laparoscopic surgery for gastric cancer was performed for 71 patients (Intra group). During same period, 231 patients underwent laparoscopy-assisted gastrectomy (Extra group). These patients were classified into initial (1st to 20th case of intra group), intermediate (21th to 46th case), and experienced (after 47th case) phases. Results: Intracorporeal procedures included 35 cases of Billroth-I, 30 Billroth-II and 6 Roux en Y reconstructions. In the initial phase,operation time (P=0.022) were significantly longer for the patients of intra group than them of extra group. Although the difference was not significant, the length of hospital stay was longer and complication rate was higher in the intra group. In intermediate and experienced phases, there was no difference between two groups in operation time and hospital stay. In these phases, complication rate was lower in the intra group than the extra group (3.9% versus 9.7%). The pain scale was significantly lower post operation day 5 in the intra group. Conclusions: Intracorporeal reconstruction after laparoscopic distal gastrectomy was feasible and safe, and the technique was stabilized after 20th case if the surgeon has sufficient experiences when we compared it with extracorporeal reconstruction.
이동 Ad-hoc 네트워크를 위한 가상 클러스터 방식의 경로 설정 프로토콜
안창욱,강충구 한국통신학회 2002 韓國通信學會論文誌 Vol.27 No.c6
본 논문에서는 이동 ad-hoc 네트워크(Mobile Ad-hoc Networks)에서 인접 단말(node)간에만 경로 설정 정보를 교환하는 협의의 네트워크인 가상 클러스터(Virtual Cluster)를 정의하고, 이를 기반으로 하는 새로운 형태의 혼합 방식 경로 설정 프로토콜(Virtual Cluster-based Routing Protocol. VCRP)을 제안한다. 이는 단말이 전체 네트워크의 구성 및 비용 정보를 알고 즉시 경로를 설정할 수 있는 Proactive Routing Protocol (PRP)이 갖는 짧은 전송 지연시간의 장점과 모든 단말이 자신을 제외한 어떠한 단말과도 정보를 교환하지 않고 단지 경로탐색 패킷(Route Query Packet)에 의존하여 동작하는 Reactive Routing Protocol (RRP)이 갖는 우수한 오버헤드 효율성의 장점을 동시에 만족하도록 설계된 방식이다. 이는 경로탐색 패킷이 가상 클러스터가 갖는 장점을 이용하여 적은 오버헤드로 신속하게 네트워크 토폴로지 정보의 수집이 가능한 형태로 수정된 전파(flooding) 기법에 기인한 것이다. 또한, 제안 방식은 수집된 정보를 기반으로 최적 경로뿐만 아니라 부수적으로 백업 경로를 동시에 파악할 수 있기 때문에 이를 이용하는 프로토콜(Virtual Cluster-based Routing Protocol with Backup Route: VCBRP)도 고려하였다. VCRP와 VCBRP 방식은 네트워크 토폴로지 변화에 대해 강인한 특성을 지니며, 동시에 패킷 전송 지연(Packet Transfer Delay), 링크 단절률(Link Failure Ratio), 그리고 무선 자원 수율(Throughput) 및 오버헤드 효율성의 성능이 기존의 경로 설정 프로토콜들에 비해 우수함을 모의 실험을 통해 검증했다. In this paper, we propose a new hybrid type of the routing protocol (Virtual Cluster-based Routing Protocol: VCRP) for mobile ad-hoc networks, based on a virtual cluster, which is defined as a narrow-sense network to exchange the basic information related to the routing among the adjacent nodes. This particular approach combines advantage of proactive routing protocol (PRP), which immediately provides the route collecting the network-wide topological and metric information, with that of reactive routing protocol, which relies on the route query packet to collect the route information on its way to the destination without exchanging any information between nodes. Furthermore, it also provides the back-up route as a byproduct, along with the optimal route, which leads to the VCBRP (Virtual Cluster-based Routing Protocol with Backup Route) establishing the alternative route immediately after a network topology is changed due to degradation of link quality and terminal mobility, Our simulation studies have shown that the proposed routing protocols are robust against dynamics of network topology while improving the performances of packet transfer delay, link failure ratio, and throughput over those of the existing routing protocols without much compromising the control overhead efficiency.