• 상하수도학회지
• /
• 제29권3호
• /
• pp.395-406
• /
• 2015

This research carried out an analysis on input cost and leakage reduction effect by leakage reduction method, focusing on the project for establishing an optimal water pipe network management system in the Taebaek region, which has been executed annually since 2009. Based on the result, optimal cost-benefit analysis models for water distribution network rehabilitation project were developed using DEA(data envelopment analysis) and multiple regression analysis, which have been widely utilized for efficiency analysis in public and other projects. DEA and multiple regression analysis were carried out by applying 4 analytical methods involving different ratios and costs. The result showed that the models involving the analytical methods 2 and 4 were of low significance (which therefore were excluded), and only the models involving the analytical methods 1 and 3 were suitable. From the result it was judged that the leakage management method to be executed with the highest priority for the improvement of revenue water ratio was installation of pressure reduction valve, followed by replacement of water distribution pipe, replacement of water supply pipe, and then leakage detection and repair; and that the execution of leakage management methods in this order would be most economical. In addition, replacement of water meter was also shown to be necessary in case there were a large number of defective water meters.

• 한국통신학회논문지
• /
• 제34권11A호
• /
• pp.870-881
• /
• 2009

의료 IT 기술 발전과 함께 의료 디지털 도서관, 3D PACS, 3D 의료진단기기 등의 헬스케어 정보 관리 기술이 급격히 발전되면서 이에 대한 보안 이슈가 제기되고 있다. 본 논문에서는 헬스케어 정보 관리 시스템에서 3D 의료영상 데이터의 저작권 보호, 인증, 인덱싱 및 진단 정보 은닉 등을 위한 다중 워터마킹 기법을 제안한다. 제안한 기법에서는 POCS 워터마킹 기반으로 의료진의 디지털 서명 및 정보 검색 인덱싱을 위한 강인한 워터마크를 꼭지점 정규곡률 분포에 삽입하고, 진단 정보와 인증 기준 메시지를 위한 연약한 워터마크를 꼭지점 거리 차이에 삽입한다. 이 때 강인성, 연약성 및 비가시성에 대한 각각의 볼록 집합들을 설계한 다음, 3D 의료영상 데이터들을 이들 집합으로 반복 투영함으로써 다중 워터마크를 삽입한다. 실험 결과부터 제안한 기법이 다양한 3D 기하학 및 메쉬 변형에 대한 강인성과 연약성을 모두 만족함을 확인하였다.

• 한국측량학회:학술대회논문집
• /
• 한국측량학회 2006년도 춘계학술발표회 논문집
• /
• pp.501-506
• /
• 2006

With the development of Geospatial Technology (GT), many countries and industries have been expanding their investment in constructing a cyber territory. As the critical components of this cyber territory, three-dimensional models and virtual reality contents based on these models of urban areas in particular have been considered. These models and contents can be intensively used for a city to decide the policies efficiently and to attract the interests of peoples while planning and performing large projects. In this study, we have thus constructed the 3D models and virtual reality contents of the large areas along the CheongGye stream to visualize the environment of these areas before and after the CheongGyeCheon restoration project being completed. Furthermore, we propose efficient methods to construct and visualize these large models, such as tile mapping and multiple LOD application.

• 산업경영시스템학회지
• /
• 제31권3호
• /
• pp.74-79
• /
• 2008

The reinvestment assumption of the internal rate of return(IRR) method may not be valid in an engineering economy study. This situation, coupled with the computational demands and possible multiple interest rate associated with the IRR method, has given rise to other rate of return methods, such as the external rate of return(ERR) method, that can remedy some of these weaknesses. But ERRs are not used generally. We present another rate of return including all attributes of the minimum attractive rate of return(MARR).

• 한국건설관리학회논문집
• /
• 제6권5호
• /
• pp.69-77
• /
• 2005

Change is inevitable and is a reality of construction projects. Most construction contracts include change clauses and allowing contractors an equitable adjustment to the contract price and duration caused by change. However, the actions of a contractor can cause a loss of productivity and furthermore can result in disruption of the whole project because of a cumulative or ripple effect. Because of its complicated nature, it becomes a complex issue to determine the cumulative impact (ripple effect) caused by single or multiple change orders. Furthermore, owners and contractors do not always agree on the adjusted contract price for the cumulative Impact of the changes. A number of studies have attempted to quantify the impact of change orders on project costs and schedule. Many of these attempted to develop regression models to quantify the loss. However, regression analysis has shortcomings in dealing with many qualitative or noisy input data. This study develops ANN models to classify and quantify the labor productivity losses that are caused by the cumulative impact of change orders. The results skew that ANN models give significantly improved performance compared to traditional statistical models.

• Journal of Construction Engineering and Project Management
• /
• 제6권2호
• /
• pp.16-23
• /
• 2016

The use of inappropriate procurement methods to deliver construction projects has long been acknowledged as a major source of poor project performance and is particularly problematic for the Libyan Construction Industry. Poor procurement method selection has been recognised as a major contributory factor to frequent time and cost overruns. This paper offers a way of selecting specific procurement methods to maximize successful project performance. The methodology involves an intensive review of relevant literature, followed by a semi-structured questionnaire survey. The key findings of the study reveal that 11 out of its 12 common selection criteria exhibit a significant contribution to one or more project performance criteria (time, cost and quality). Project clients should therefore prioritise these criteria when selecting a design-bid-build method. Knowledge of the criteria that contribute positively to project performance will also enable clients to work out, prior to and during construction, the best measures and provisions for successful project outcomes.

• 한국CDE학회논문집
• /
• 제17권3호
• /
• pp.164-174
• /
• 2012

The recent introduction of BIM technology has raised the interest on the BIM quality assurance and management more than ever. This study aims to consider the ways of BIM quality improvement by analyzing the most frequent issues rising from multiple BIM projects. For this purpose, the 12 test models from BIM education program hosted by buildingSMART Korea are investigated based on the requirements in the public BIM guidelines. All the BIM issues generated are categorized by the criteria applied and analyzed for each kind of building element. The results showed that more than half of the issued at least could be cleared out by improving modeling habits and technical guides.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
• /
• pp.101-104
• /
• 2007

Efficient Query processing and optimization are critical for reducing network traffic and decreasing latency of query when accessing and manipulating sensor data of large-scale sensor networks. Currently it has been studied in sensor database projects. These works have mainly focused on in-network query processing for sensor networks and assumes homogeneous sensor networks, where each sensor network has same hardware and software configuration. In this paper, we present a framework for efficient query processing over heterogeneous sensor networks. Our proposed framework introduces query processing paradigm considering two heterogeneous characteristics of sensor networks: (1) data dissemination approach such as push, pull, and hybrid; (2) query processing capability of sensor networks if they may support in-network aggregation, spatial, periodic and conditional operators. Additionally, we propose multi-query optimization strategies supporting cross-translation between data acquisition query and data stream query to minimize total cost of multiple queries. It has been implemented in WSN middleware, COSMOS, developed by ETRI.

• 환경영향평가
• /
• 제15권1호
• /
• pp.13-22
• /
• 2006

The Korean government adopted the integrated stream water management policy recently with growing perception that natural disasters and pollution in Korea have been due not only to such human factors as urbanization and industrialization, but also to the policy of functionally separated management of irrigation, flood control and ecological management. Contrary to its good intention, research result shows that it is not realistic to expect that this new integrated policy in Korea will work well. In order to be an effective policy and program evaluation, this paper suggests that evaluation indicator on related programs and projects should be made through bottom-up process. For example, environmental benefit should be taken into account rather than just economic benefit, and cultural and social characteristics in the project region should be also considered seriously.

• 공학교육연구
• /
• 제13권2호
• /
• pp.74-77
• /
• 2010

This article proposes to examine how the study of failure differs from other technical subjects, and how to turn failure experiences to one's advantage. The authors surveyed the properties of failures in PBL (Project Based Learning) and also examined students' interest and understanding of failure, after introducing failure examples. To investigate how students communicate failure experiences to third parties, reports of the failure experience in PBL were evaluated. From above mentioned surveys, we get the following results. The typical causes of failure in educational institutions are lack of skill in manufacturing and inadequate planning, which conversely are minor causes of failure in the industry. A knowledge database on failure, employed commonly in industry, is not effective in PBL, because projects in educational institutes are usually changed every year. Case studies in failure can be approached from many points of view including causes, processes, effects and safety measures. While teachers should emphasize the notable points in the failure examples in introducing examples of specific topics in machine design, teachers should explain the multiple aspects in the failure examples to educate students about the complexity of actual accidents.