• Structural Engineering and Mechanics
• /
• 제70권4호
• /
• pp.457-466
• /
• 2019

This study develops a damage detection method based on neural networks. The performance of the method is numerically and experimentally verified using a three-story shear building model. The framework is mainly composed of two hierarchical stages to identify damage location and extent using artificial neural network (ANN). The normalized damage signature index, that is a normalized ratio of the changes in the natural frequency and mode shape caused by the damage, is used to identify the damage location. The modal parameters extracted from the numerically developed structure for multiple damage scenarios are used to train the ANN. The positive alarm from the first stage of damage detection activates the second stage of ANN to assess the damage extent. The difference in mode shape vectors between the intact and damaged structures is used to determine the extent of the related damage. The entire procedure is verified using laboratory experiments. The damage is artificially modeled by replacing the column element with a narrow section, and a stochastic subspace identification method is used to identify the modal parameters. The results verify that the proposed method can accurately detect the damage location and extent.

• 국토계획
• /
• 제54권1호
• /
• pp.52-66
• /
• 2019

Travel is a factor that stimulates the vitality of the urban and is widely used as an indicator of sustainable growth of the region. In Korea, however, no studies has been made to predict changes in traffic and calculate the accessibility of the region by comprehensively considering the socio-economic conditions of the travelers. The purpose of this study is to classify commuters according to the household income and to analyse the traffic characteristics of each class. The analysis results are aggregated into two. First, the analysis of study found different transport characteristics for different income classes. This is the result that underpins the argument of a previous study that suggested that a discriminatory approach is necessary for each income in determining the accessibility of the region. Second, this study calculated utility values differently for each income class based on the transit time and cost required between each zone. Through these measures, transport characteristics were analyzed by income class using indicators that considered transportation infrastructure, and socio-economic conditions of the travelers. This study is meaningful in that it provided the basis for calculating the accessibility that could take into account the activities of the housing consumers in establishing domestic housing policies.

• 한국정보과학회논문지:정보통신
• /
• 제33권1호
• /
• pp.38-48
• /
• 2006

무선 랜의 영역 확장을 위해서 무선 랜과 유사한 2계층 프로토콜(1)을 사용하는 이동 애드 혹 네트워크의 인터네트워킹 기법을 (2)에서 제안하고 있다. 이 기법은 무선 랜 확장을 위한 UMTS (Universal Mobile Telecommunications Systems)와 무선 랜의 인터네트워킹 기법(3-4)에 비해 물리 및 논리적인 특성이 유사하기 때문에 상대적으로 낮은 오버헤드와 지연을 갖는다는 장점이 있다. 애드 흑과 무선 랜간의 인터네트워킹을 위해 (2)가 제안하고 있는 모드 변환 알고리즘은 시그널 강도만을 고려하여 핸드오프를 결정하기 때문에 상이한 시그널을 수신하는 영역에 지그재그로 이동하는 경우 빈번한 핸드오프를 야기 시킬 수 있다. 또, 무선 랜에서의 이동성 지원이 MIPv6 프로토콜을 기반으로 하고 있어서 핸드오프시 높은 지연을 갖고 시그널 메시지 교환으로 인한 오버헤드가 크다. 본 논문에서는 (2)에서 제안하는 스위칭 기법을 수정 및 보완함으로써 이동 노드가 HMIPv6를 기반으로 하고 있는 무선 랜의 범위를 벗어나 난청지역(dead-spot)에 진입했을 때 무선 랜 영역의 확장을 위해서 무선 랜과 이동 애드 혹 네트워크간의 최적화된 인터네트워킹 방안을 제안한다. (2)에서 발생할 수 있는 핸드오프 핑퐁문제를 적응적인 임계치를 반영함으로써 해결하였다. 특히, 무선 랜에서 이동성 지원을 위한 HMIPv6 프로토콜과 병립되어 사용될 수 있는 OLSR 프로토콜을 이동 애드 혹 네트워크에서 적용하였다. 총 오버헤드 시간을 구하고 실험과 시뮬레이션을 통해 제안된 스위칭 방식이 기존의 방식보다 성능이 우수함을 확인하였다.

• 한국산업정보학회논문지
• /
• 제22권1호
• /
• pp.1-9
• /
• 2017

무선 네트워크 기술과 무선 전송 기술의 발전으로 인해 무선 전달망(Wireless Transit Network) 구성 기술로서 무선 메시 네트워크(WMN)가 관심을 받고 있다. 오랜 기간 다양한 영역에서 WMN에 대한 연구가 진행되었지만 아직 해결되지 않은 문제들이 많이 남아있다. 그 중 하나가 무선 링크로 구성된 다중 홉 네트워크에서 최적 경로를 찾는 라우팅 문제이다. WMN의 3가지 구성유형 중 하나인 하이브리드 WMN에서 최적 경로 선택을 위해서는 우수한 성능의 메트릭 연구와 함께 효과적으로 인프라스트럭처 메시를 전달망으로 사용하기 위한 경로 검색 프로토콜 연구가 필요하다. 따라서 본 논문에서는 하이브리드 WMN을 위한 듀얼모드-AODV(Ad hoc On-demand Distance Vector)를 제안한다. 본 논문에서 제안된 듀얼모드-AODV를 하이브리드 WMN에 적용하는 경우 AODV에 비하여 경로 검색 지연시간이 52% 감소하는 것을 시뮬레이션을 통해 확인하였다.

• Asian Journal for Public Opinion Research
• /
• 제9권4호
• /
• pp.331-351
• /
• 2021

The unprecedented situation of COVID-19 caused the government of India to instruct educational institutions to switch to an online mode to mitigate the losses for students due to the pandemic. The present study attempts to explore the impact of online learning introduced as a stop-gap arrangement during the pandemic in India. A survey was conducted (N=289), via Facebook and WhatsApp, June 1-15, 2020 to understand the accessibility and effectiveness of online learning and constraints that students of higher education across the country faced during the peak times of the pandemic. The analysis and interpretation of the data revealed that the students acclimatized in a short span of time to online learning, with only 33.21% saying they were not satisfied with the online learning mode. However, the sudden shift to online education has presented more challenges for the socially and economically marginalized groups, including Scheduled Caste (SC), Scheduled Tribes (ST), Other Backward Class (OBC), females, and students in rural areas, due to factors like the price of high-speed Internet (78.20% identified it as a barrier to online learning), insufficient infrastructure (23.52% needed to share their device frequently or very frequently), poor Internet connectivity, etc. According to 76.47% of respondents, the future of learning will be in "blended mode." A total of 88.92% of the respondents suggested that the government should provide high-quality video conferencing facilities free to students to mitigate the division created by online education in an already divided society.

• 한국프랜차이즈경영연구
• /
• 제2권2호
• /
• pp.134-149
• /
• 2011

최근 들어 기업의 사회적 책임(CSR)에 관한 기업과 학자들의 관심이 갈수록 증대하고 있다. 기업의 사회적 책임의 속성 중 일반적으로 기업의 역할론을 집중적으로 조명하고 있다. 더욱이 국제표준화기구(ISO)가 기업의 실제적 규범으로ISO900, ISO1400을 지정한 후, 2010년 11월 ISO가 ISO26000을 기업의 사회적 책임의 새로운 가이드라인으로 선언하면서 그 중요성이 훨씬 증대되었다. 경제전환시대에 이르러, 중국에서도 기업의 사회적 책임에 관한 중요성이 날로 증가하고 있다. 2011년 중국사회과학원의 '중국기업의 사회책임에 관한 보고'에 의하면, 중국기업의 사회책임수준은 초기단계로서, 아직까지 낮은 수준에 머무르고 있다. 특히 베이징은 중국의 수도로서 정치, 문화, 국제, 중국내 교류 중심지로서, 중국에서 가장 큰 소매시장이 형성되었고, 세계 10대 소비도시로 소매기업이 꾸준히 발전하고 있다. 그러나 아직까지 베이징 소매기업에 대한 기업의 사회적 책임에 관한 관리모형에 대한 연구가 부족한 현실이다. 본 논문은 중국 및 베이징의 소매기업의 사회적책임에 관한 관리현황을 파악하였다. 그리고 정부주도하의 베이징의 소매기업의 사회적 책임 관리모형을 4개 측면에서 수립하였다. 또한 기업이 계속적인 경쟁력을 유지하기 위해 소매기업의 사회적 책임을 수행할 수 있도록 5가지 시행방안을 제안하였다.

• Asian Journal for Public Opinion Research
• /
• 제3권1호
• /
• pp.22-39
• /
• 2015

This research is a qualitative based study by using data gleaned from documentary analysis and in-depth interviews of 10 potential stakeholders were involved in the proposed high-speed train project in Thailand. Many perspectives from key informants revealed that this project would bring Thailand sustainable development in the future due to the fact that it is supposed to be an environmentally friendly mode of transportation and timesaving for passengers. Key informants who tend to have negative opinions towards the project feel apprehension due to the huge monetary investment during a time of monetary crisis. However, there was one complaint that the high-speed train is harmful to the environment surrounding the proposed area of this project. Several key informants agreed that ticket fares must be in between the cost of a bus ticket and airfare.

• Structural Engineering and Mechanics
• /
• 제75권3호
• /
• pp.311-325
• /
• 2020

In applying the spectral stochastic finite element methods to the frequency response analysis, the conventional methods are known to give unstable and inaccurate results near the natural frequencies. To address this issue, a new sensitivity based stabilized formulation for stochastic frequency response analysis is proposed in this paper. The main difference over the conventional spectral methods is that the polynomials of random variables are applied to both numerator and denominator in approximating the harmonic response solution. In order to reflect the resonance behavior of the structure, the denominator polynomials is constructed by utilizing the natural frequency sensitivity and the random mode superposition. The numerator is approximated by applying a polynomial chaos expansion, and its coefficients are obtained through the Galerkin or the spectral projection method. Through various numerical studies, it is seen that the proposed method improves accuracy, especially in the vicinities of structural natural frequencies compared to conventional spectral methods.

• 한국해양공학회지
• /
• 제17권6호
• /
• pp.96-100
• /
• 2003

For moving cargo between the North Pacific region and Northern European ports, the Northern Sea Route, along Russia's coastline, is 35-60％ shorter than the traditionally used routes through the Suez or Panama Canals. in addition to its shorter distance, there exist extensive ports und shipping infrastructure, and the potential for developing new markets in Russia and other northern countries including Korea and Japan. These incentives attracted considerable attention from the international shipping and shipbuilding industries and have formed a cooperative international research program, called as the International Northern Sea Route Programme (INSROP) This paper is a general compilation of the historical usage, recent trade developments, the physical environment, and the practical considerations that may shape future operational mode of shipping in the NSR based on results from INSROP reports. This study focuses mainly on an operation of commercial icebreaking cargo vessels that may be utilized along the NSR.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회 2007년도 추계학술대회 및 정기총회
• /
• pp.377-382
• /
• 2007

Mobile ad hoc network(MANET) is a kind of wireless network which has no infrastructure. Each component node of MANET can move freely and communicate based on wireless peer to peer mode. Because of its vulnerable routing protocols, MANET is exposed to many kinds of attacks. A sinkhole attack is one of the representative attacks in MANET caused by attempts to draw all network traffic to a sinkhole node. This paper focuses on the sinkhole problem on Dynamic Source Routing(DSR) protocol in MANET. To detect the sinkhole node, we extract several useful sinkhole indicators through analyzing the sinkhole problem, then propose an efficient detection method based on an incremental learning algorithm. The simulation results show that the proposed method is effective and reliable for detecting sinkhole intrusion.