• Smart Structures and Systems
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• 제1권1호
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• pp.1-12
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• 2005

This paper describes the area of intelligent systems research as funded by the Civil and Mechanical Systems (CMS) Division of the National Science Foundation (NSF). With developments in computer science, information technology, sensing and control the design of typical machines and structures by civil and mechanical engineers is evolving toward intelligent systems that can sense, decide and act. This trend toward electro-mechanical design is well-established in modern machines (e.g. vehicles, robots, disk drives) and often referred to as mechatronics. More recently intelligent systems design is becoming an important aspect of structures, such as buildings and bridges. We briefly review recent developments in structural control, including the role that NSF has played in their development, and discuss on-going CMS activities in this area. In particular, we highlight the interdisciplinary initiative on Sensors and Sensor Networks and the Network for Earthquake Engineering Simulation (NEES). NEES is a distributed cyberinfrastructure to support earthquake engineering research, and provides the pioneering NEES grid computing environment for simulation, teleoperation, data collection and archiving, etc.

• Smart Structures and Systems
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• 제16권6호
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• pp.1107-1132
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• 2015

A damage detection algorithm based on neuro fuzzy hybrid system is presented in this study for location and severity predictions of cracks in beam-like structures. A combination of eigenfrequencies and rotation deviation curves are utilized as input to the soft computing technique. Both single and multiple damage cases are considered. Theoretical expressions leading to modal properties of damaged beam elements are provided. The beam formulation is based on Euler-Bernoulli theory. The cracked section of beam is simulated employing discrete spring model whose compliance is computed from stress intensity factors of fracture mechanics. A hybrid neuro fuzzy technique is utilized to solve the inverse problem of crack identification. Two different neuro fuzzy systems including grid partitioning (GP) and subtractive clustering (SC) are investigated for the highlighted problem. Several error metrics are utilized for evaluating the accuracy of the hybrid algorithms. The study is the first in terms of 1) using the two models of neuro fuzzy systems in crack detection and 2) considering multiple damages in beam elements employing the fused neuro fuzzy procedures. At the end of the study, the developed hybrid models are tested by utilizing the noise-contaminated data. Considering the robustness of the models, they can be employed as damage identification algorithms in health monitoring of beam-like structures.

• World Technopolis Review
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• 제8권1호
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• pp.59-70
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• 2019

Where is a better place to live? In the coming era, this should be more than simply a livable place. It should be an adaptable place that has a flexible system adaptable to any new situation in terms of diversity. Customization and real-time operation are needed in order to realize this technologically. We expect a smart city to have a flexible system that applies technologies of self-monitoring and self-response, thereby being a promising city model towards being a better place to live. Energy demand and supply is a crucial issue concerning our expectations for the flexible system of a smart city because it is indispensable to comfortable living, especially city living. Although it may seem that energy diversification, such as the energy mix of a country, is a matter of overriding concern, the central point is the scale of place to build grids for realizing sustainable urban energy systems. A traditional hard energy path supported by huge centralized energy systems based on fossil and nuclear fuels on a national scale has already faced difficult problems, particularly in terms of energy flexibility/resilience. On the other hand, an alternative soft energy path consisting of small diversified energy systems based on renewable energy sources on a local scale has limitations regarding stability, variability, and supply potential despite the relatively light economic/technological burden that must be assumed to realize it. As another alternative, we can adopt a holonic path incorporating an alternative soft energy path with a traditional hard energy path complimentarily based on load management. This has a high affinity with the flexible system of a smart city. At a system level, the purpose of all of the paths mentioned above is not energy itself but the service it provides. If the expected energy service is fixed, the conclusive factor in choosing a more appropriate system is accessibility to the energy service. Accessibility refers to reliability and affordability; the former encompasses the level of energy self-sufficiency, and the latter encompasses the extent of energy saving. From this point of view, it seems that the small diversified energy systems of a soft energy path have a clear advantage over the huge centralized energy systems of a hard energy path. However, some insuperable limitations still remain, so it is reasonable to consider both energy systems continuing to coexist in a multiplexing energy system employing a holonic path to create and maintain reliable and affordable access to energy services that cover households'/enterprises' basic energy needs. If this is embodied in a smart city concept, this is nothing else but smart energy inclusion. In Japan, following the Fukushima nuclear accident in 2011, a trend towards small diversified energy systems of a soft energy path intensified in order to realize a nuclear-free society. As a result, the Government of Japan proclaimed in its Fifth Strategic Energy Plan that renewable energy must be the main source of power in Japan by 2050. Accordingly, Sony vowed that all the energy it uses would come from renewable sources by 2040. In this situation, it is expected that smart energy inclusion will be achieved by the Japanese version of a smart grid based on the concept of a minimum cost scheme and demand response.

• 전기학회논문지P
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• 제65권1호
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• pp.1-6
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• 2016

Recently, proportion of the induction motor load is gradually increased. When a contingency in the power systems, it has been discovered phenomenon that the voltage is delayed recover caused mechanical characteristics of the induction motor load. It can be a serious impact on the voltage stability of the power system considering induction motor load. The scheme to mitigate this phenomenon tripping off the motors to prevent voltage drop and delayed voltage recovery on the load demand side. Fault induced delayed voltage recovery phenomenon is caused by stalling of small induction motor load in transmission level contingencies. In this paper, fault induced delayed voltage recovery phenomenon mitigation method implementation under voltage load shedding on the korean power system considering induction motor load.

• 상하수도학회지
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• 제30권6호
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• pp.653-662
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• 2016

Recently, advanced metering infrastructure (AMI) has been recognized as a core technology of smart water grid, and the relevant market is growing constantly. In this study, we developed all-in-one smart water meter of the AMI system, which was installed on the test-bed to verify both effectiveness and field applicability in office building water usage. Developed 15 mm-diameter smart water meter is a magneto-resistive digital meter, and measures flow rate and water quality parameters (temperature, conductivity) simultaneously. As a result of the water usage analysis by installing six smart water meters on various purposes in office building water usage, the water usage in shower room showed the highest values as the 1,870 L/day and 26.6 liter per capita day (LPCD). But, the water usage in laboratory was irregular, depending on the many variables. From the analysis of the water usage based on day of the week, the water usage on Monday showed the highest value, and tended to decrease toward the weekend. According to the PCA results and multivariate statistical approaches, the shower room (Group 3) and 2 floor man's restroom sink (Group 1-3) have been classified as a separate group, and the others did not show a significant difference in both water use and water quality aspects. From the analysis of water usage measured in this study, the leak or water quality accident did not occur. Consequently, all-in-one smart water meter developed in this study can measure flow rate and water quality parameters (temperature, conductivity) simultaneously with effective field applicability in office building water usage.

• 전기학회논문지
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• 제60권6호
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• pp.1261-1267
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• 2011

Electricity meters using in Korea are about 1.8 million units. From among these, electronic meters for high voltage, about 170 thousand units were installed to the digital type meter and ones for low voltage installed hundreds of thou-sands of meters through a model project. Recently, low voltage meter are expected to complete the installation within several years. Domestic power metering technology is being beyond a simple framework with an electronic type and is rapidly evolving to intelligent smart metering systems in conjunction with promotion of a national smart grid project. Accordingly, it is important to ensure an immunity of meter for electromagnetic field and environmental noise at the installation site. In this paper, we are going to check the validity of international standard that focusing on RF electromagnetic field immunity of meter to secure the quality and improve the reliability in field operation of meter. And we will verify the validity of test specification focused on actual installation environment and are going to offer the improvement plan of test standard.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1961-1971
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• 2006

A soft recovery system (SRS) is a device that stops a high speed projectile without damaging the projectile. The SRS is necessary to verify the shock resistant requirements of microelectronics and electro-optic sensors in smart munitions, where the projectiles experience over 20,000 g acceleration inside the barrel. In this study, a computer code for the performance evaluation of a SRS based on ballistic compression decelerator concept has been developed. It consists of a time accurate compressible one-dimensional Euler code with use of deforming grid and a projectile motion analysis code. The Euler code employs Roe's approximate Riemann solver with a total variation diminishing (TVD) method. A fully implicit dual time stepping method is used to advance the solution in time. In addition, the geometric conservation law (GCL) is applied to predict the solutions accurately on the deforming mesh. The equation of motion for the projectile is solved with the four-stage Runge-Kutta time integration method. A small scale SRS to catch a 20 mm bullet fired at 500 m/s within 1,600 g-limit has been designed with the proposed method.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2012년도 제46차 하계학술발표논문집 20권2호
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• pp.47-50
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• 2012

본 연구에서는 수용가에서 에너지 절감과 최대수요전력 제어를 위하여 마이크로프로세서를 이용한 고효율 자동 전압 조정기의 제어 방법에 대하여 제안한다. 제안한 고효율 자동 전압 조정기는 트로이달 코아에 1개의 직렬 권선과 분리된 4개의 분로 권선으로 구성되어 있는 단권 변압기를 사용한다. 변압기의 전압 조정은 직렬 권선과 분로 권선의 연결 방법에 따라 감압/승압이 가능하다. 스위치는 릴레이와 트라이악을 병행하여 사용한다. 스위치의 조작 시 발생하는 권선의 여자돌입전류를 제어하기 위하여 트라이악을 이용 연결 상태를 변경하고 연결 상태 유지 시에는 릴레이를 이용함으로써 스위치 소비 전력을 최소화 한다. 제어신호는 여자 돌입 전류를 줄이기 위하여 전압 파형에 동기화 하여 제어되며 이를 위하여 소프트웨어 PLL을 사용한다. 소프트웨어 PLL은 전압 파형의 zero-cross, 전압 최고점 등의 시간을 생성한다. 권선 스위치의 제어, 소프트웨어 PLL등 자동 전압 조정기의 제어는 마이크로프로세서에 의해서 이루어진다.

• 정보와 통신
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• 제31권6호
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• pp.64-68
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• 2014

본고에서는 수자원관리의 새로운 패러다임인 스마트워터그리드에 대한 간략한 소개와 연구단에서 개발되는 기술의 확산을 위한 추진 전략을 알아본다. 스마트워터그리드 연구단은 51개의 참여기업과 303명의 참여 연구원이 크게 3개의 세부로 나뉘어 연구를 진행한다. 1세부는 신도시 수자원 연계활용을 위한 지능형 수자원 확보 기술 개발을, 2세부는 수자원 최적 활용을 위한 지능형 유역물관리 플랫폼 개발을, 3세부에서는 Smart Water Grid 맞춤형 ICT기반물정보 관리 기술 개발을 목표로 하고 있다. 이렇게 개발되는 기술의 확산을 위해 크게 5가지의 전략을 펼치고 있다. 기술실증화 전략인 Pilot-Plant와 Demo-Plant 설계 및 운영, 표준분류체계, 국제표준화 ITU-T FG-SWM, 제7차 세계물포럼, 국제기술협력을 위한 국제컨퍼런스 개최가 연구단의 전략이다. 특히, 스마트워터그리드라는 새로운 패러다임을 국제적인 이슈로 상정하기 위하여 국제표준화 기구인 UN-ITU에 SWM(Smart Water Management) 주제로 FG(Focus Group)을 신설하였다. ITU-T는 전기 통신 분야의 국제기구로서 신기술이 개발될 때부터 기술표준화를 제시하고, 제품의 수출입에 영향력을 미치기에 많은 전기전자통신 업계의 주요 관심분야이기도 하다. SWG연구단에서도 SWM차원에서 SWG기술이 향후 세계시장에서 선진기술들과 비교경쟁력을 갖출 수 있도록 국제표준화를 위한 노력을 기울이고 있다. 또한, 2015년에 개최될 세계 제 7차 물포럼에서 SWG기술을 시연하고, 홍보하는 활동을 통해 대한민국의 우수한 IT기술이 물산업의 중심에서 돋보일 것이라 전망된다.

• 한국정보통신학회논문지
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• 제17권4호
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• pp.815-821
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• 2013

본 논문에서는 스마트미터의 북미 국제표준인 ANSI C12.22에서 정의하는 C12.22 노드의 응용계층 프로토콜을 구현하였다. ANSI C12.22에서는 OSI 7 계층 중에서 응용계층만을 정의하고 있다. 정보전송에 필수 요소인 1~4 계층은 기존에 사용되고 있는 프로토콜을 사용할 것을 권고하고 있으며, 이에 따라 본 논문에서는 통상적으로 사용되고 있는 TCP/IP 프로토콜을 전송계층 및 네트워크계층 프로토콜로 사용하였다. ANSI C12.19에서는 전력량계에 사용되는 파라미터들을 규정하고 있으며, C12.22 응용계층은 이 전력량계 파라미터들을 네트워킹하기 위한 최소한의 네트워크 서비스와 데이터 구조들을 정의하고 있다. 이러한 서비스와 데이터 구조들은 네트워킹된 전력량계를 설정, 프로그래밍, 모니터링하거나 전력량계의 정보를 수집할 목적으로 사용된다. 본 논문에서는 C12.22 응용계층을 소프트웨어로 구현하기 위해 임베디드 보드를 사용하였고, 기능 테스트를 위해서 AMI 응용서버 역할을 하는 테스트 프로그램을 동시에 개발하였다.