• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.12B
• /
• pp.800-808
• /
• 2007

With the development of wireless data communication technology, all IP-based network will become compositions of wired and wireless networks. TCP is a connection-oriented, reliable transport protocol and has been used as de facto standard in most wired networks. Because TCP's congestion control algorithm could not distinguish congestion from BER, link failure and frequent route changes, TCP shows a poor performance over mobile ad-hoc networks. In this paper, the theoretical feature of TCP was studied and the performance of TCP over mobile ad-hoc networks was analyzed with ns2.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.2
• /
• pp.267-277
• /
• 1993

A finite element method(FEM) is presented and applied to the two-dimensional bottom turbulent boundary layer. The time-dependent incompressible motion of a viscous fluid is formulated by using the well-known Navier-Stokes equations and vorticity equation in terms of the velocity and pressure fields. The general numerical formulation is based on Galerkin method and solved by introducing the mixing length theory of Prandtl for eddy kinematic viscosity of a turbulent flow field. Numerical computations of the transport of sediment on an arbitrary sea-bed due to wave motion in the turbulent boundary layer are carried out. The results obtained by the FEM made clear the difference in characteristic features between the boundary layer due to oscillatory flow and the boundary layer due to wave motion.

• Annual Conference on Human and Language Technology
• /
• 2001.10d
• /
• pp.146-154
• /
• 2001

본 논문에서는 개념망 구축을 위해 사전 뜻풀이말에서 추출 가능한 의미속성의 분포 정보를 기반으로 어휘 연관도를 측정하고자 한다. 먼저 112,000여 개의 사전 뜻풀이말을 대상으로 품사 태그와 의미 태그가 부여된 코퍼스에서 의미속성을 추출한다. 추출 가능한 의미속성은 체언류, 부사류, 용언류 등이 있는데 본 논문에서는 일차적으로 명사류와 수식 관계에 있는 용언류 중 관형형 전성어미('ㄴ/은/는')가 부착된 것을 대상으로 한다. 추출된 공기쌍 45,000여 개를 대상으로 정제 작업을 거쳐 정보이론의 상호 정보량(MI)을 이용하여 명사류와 용언류의 연관도를 측정한다. 한편, 자료의 희귀성을 완화하기 위해 수식 관계의 명사류와 용언류는 기초어휘를 중심으로 유사어 집합으로 묶어서 작업을 하였다. 이러한 의미속성의 분포 정보를 통해 측정된 어휘 연관도는 의미속성의 공유 정도를 계산하여 개념들간에 계층구조를 구축하는 데 이용할 수 있다.

• Korean journal of communication and information
• /
• v.48
• /
• pp.306-325
• /
• 2009

This Study aims to thesis the purpose and educational methodology of media education for senior citizens. As background research, current situation and agendas regarding the media education for senior citizens were investigated. In further, quantative focal interview method was deployed to analyze recognition of teaches and education participants in media education for senior citizens. Focal interviews basis on the purpose, problems of education environment, preferred education method and suggestions of media education. The focal interview lead to in-depth opinion relying on experience of teachers and education participants. This study is expected to present the basis data for future theoretical systemization of neglected classes and for seeking educational utilization methods.

• Journal of KIISE:Computer Systems and Theory
• /
• v.37 no.3
• /
• pp.161-171
• /
• 2010

As embedded systems adopt monolithic kernels, NAND flash memory is used for swap space of virtual memory systems. While flash memory has the advantages of low-power consumption, shock-resistance and non-volatility, it requires garbage collections due to its erase-before-write characteristic. The efficiency of garbage collection scheme largely affects the performance of flash memory. This paper proposes a novel garbage collection technique which exploits data redundancy between the main memory and flash memory in flash memory-based virtual memory systems. The proposed scheme takes the locality of data into consideration to minimize the garbage collection overhead. Experimental results demonstrate that the proposed garbage collection scheme improves performance by 37% on average compared to previous schemes.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2005.11a
• /
• pp.191-194
• /
• 2005

본 논문에서는 방송 영상에서 조명효과와 크기변화 등에 강인한 얼굴패턴 검출기법을 제시한다. 제안된 얼굴검출 모델은 영상 전처리 과정과 얼굴패턴 검출 과정으로 이루어진다. 전처리 과정은 조명변화에 대한 보정기능과 다중필터에 의한 후보영역 선별기능으로 구분된다. 얼굴패턴 검출과정은 다단계의 특징지도 생성과정과 패턴분류 과정으로 이루어진다. 특징지도를 생성하기 위하여 가보(Gabor) 필터계층을 포함하는 CNN(Convolutional Neural Networks)모델을 도입하였다. 다양한 배경을 고려한 효과적인 학습을 위하여 본 논문에서는 억제성의 뉴런(Inhibitory neuron)을 포함하는 구조의 CNN모델을 적용한다. CNN으로부터 추출되는 특징집합은 최종 단계에서 WFMM(Weighted Fuzzy Min Max) 모델을 사용하여 분류된다. 이때 사용되는 특징집합의 크기는 분류기의 규모 및 계산량의 결정적인 역할을 준다. 이에 본 연구에서는 최종 분류 과정에 사용되는 특징의 수를 효과적으로 줄이기 위해 FMM모델을 사용하는 적응적인 특징 선별 기법을 제안한다. 또한 실제 영상을 통한 실험결과로부터 제안된 이론의 타당성을 고찰한다.

• Korean Journal of Social Welfare
• /
• v.64 no.4
• /
• pp.285-310
• /
• 2012

This study examined the causal relationship of between stressors and depression using the wave 1~4 of Korean Welfare Panel Study by social stress theory. According to the result, the level of depression and depressed group was decreased in the course of time. As a panel regression analysis, Factors affecting the reduction of depression was upward of the income hierarchy, increase the satisfaction of family and social relationships, and residential satisfaction. Based on the results, the author suggested that social work policies and intervention direction should decrease social stress factors with causality to depression of the men in baby boom generation.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.9
• /
• pp.349-357
• /
• 2003

Because of capacity of the electric power equipment grew larger and the electric power system was complicated, it was required a protocol to process data without the errors in order to supply the high quality and stable electric power. However, HDLC and TCP/IP communication protocol using between Seoul EMS and Kwangju RCC (or between RCC and SCC) is decreasing reliability by the delay of speed and the occurrence of errors. In this paper, we applied ICCP(Inter-Control Center Communication Protocol) communication protocol in order to improve them and implemented an electric power communication system for remote control of the electric power equipment. Also, we modified program for error correction and implemented the system using the most suitable BLT. The errors were more decreased in case of ICCP protocol than HDLC protocol and TCP/IP protocol applied to the electric power communication system.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2004.11a
• /
• pp.101-104
• /
• 2004

Business Intelligence 나 DSS 구축과 운영을 위한 근간은 기업의 통합 데이터 인프라로서의 Data Warehouse 구축이 중심을 이룬다. Data Warehouse 는 통합적, 시계열적, 비휘발적, 주제중심적 Data로 구성된다. 이러한 특성이 이론적으로 정교함에도 불구하고 현실적인 프로젝트를 진행함에 있어서 많은 어려움을 발생시킨다. 이러한 문제의 가장 핵심적인 원인이라면 운영시스템의 변화에 따른 운영상의 리스크와 함께 Subject Area 의 요소적 변경에서 그 원인을 찾을 수 있다. 초기에 Data Warehouse 가 아무리 Business User 의 요구사항을 제대로 충족시킬 수 있다 하더라도 시간의 경과에 따라 운영시스템의 변화와 Subject Area 의 요소적 변경은 피할 수 없는 사실인데 이러한 환경에 유연하게 대처할 수 있는 Data Warehouse 가 구축되지 못한다면 결국 Data Warehouse 프로젝트는 현업의 Business 적 문제와는 거리가 먼 고비용을 투자하고 아무런 수익적 가치도 내지 못하는 거추장스러운 시스템에 지나지 않을 것이다. 본 논문에서는 Dimension 관리의 핵심이라고 할 수 있는Changing Dimension 관리 기법과 함께 EDW(Enterprise Data Warehouse)방식의 아키텍처를 중심으로 한 통합데이터모델과 함께 OLAP 메타데이터에 기반한 복합적이면서도 현실적인 Data Warehouse 설계를 제시하고자 한다

• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.7_8
• /
• pp.331-340
• /
• 2003

Low-cost commodity SMP(Symmetric Multiprocessor) is widely used as a node of cluster system. In this paper, we implement and evaluate the performance of SDSM system for SMP clusters. Our SDSM system provides HLRC(Home-based Lazy Release Consistency) memory consistency model. Our protocol utilize shared memory within same SMP node, so that page fetch and message passing through network can be reduced. It is implemented on 8 node of 2-way Pentium-III SMP interconnected with 100Mbps Fast Ethernet, and uses TCP/IP for transport/network layer protocol. The experiment with eight applications shows that our SMP protocol achieves maximum 33% speedup improvement and 13%-52% reduction of page fetch compared with uniprocessor protocol.