• Journal of Power Electronics
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• 제17권5호
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• pp.1308-1316
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• 2017

The distributed maximum power point tracking (DMPPT) concept is widely adopted in photovoltaic systems to avoid mismatch loss. However, the high cost and complexity of DMPPT hinder its further promotion in practice. Based on the concept of DMPPT, this paper presents an integrated submodule level half-bridge stack structure along with an optimal current point tracking (OCPT) control algorithm. In this full power processing integrated solution, the number of power switches and passive components is greatly reduced. On the other hand, only one current sensor and its related AD unit are needed to perform the ideal maximum power generation for all of the PV submodules in any irradiance case. The proposal can totally eliminate different small-scaled mismatch effects in real-word condition and the true maximum power point of each PV submodule can be achieved. As a result, the ideal maximum power output of the whole PV system can be achieved. Compared with current solutions, the proposal further develops the integration level of submodule DMPPT solutions with a lower cost and a smaller size. Moreover, the individual MPPT tracking for all of the submodules are guaranteed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1938-1943
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• 2005

Network human-robot interface is an important research topic. In home application, users access the robotic system directly via voice, gestures or through the network. Users explore a system by using the services provided by this system and to some extend users are enable to participate in a service as partners. A service may be provided by a robot, a group of robots or robots and other network connected systems (distributed sensors, information systems, etc). All these services are done in the network environment, where uncertainty such as the unstable network connection, the availability of the partners in a service, exists. Moreover, these services are controlled by several users, accessing at different time by different methods. Our research aimed at solving this problem to provide a high available level, flexible coordination system. In this paper, a multi-agent framework is proposed. This framework is validated by using our new concept of slave agents, a responsive multi-agent environment, a virtual directory facilitator (VDF), and a task allocation system using contract net protocol. Our system uses a mixed model between distributed and centralized model. It uses a centralized agent management system (AMS) to control the overall system. However, the partners and users may be distributed agents connected to the center through agent communication or centralized at the AMS container using the slave agents to represent the physical agents. The system is able to determine the task allocation for a group of robot working as a team to provide a service. A number of experiments have been conducted successfully in our lab environment using Issac robot, a PDA for user agent and a wireless network system, operated under our multi agent framework control. The experiments show that this framework works well and provides some advantages to existing systems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.177-180
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• 1999

Nowadays, one of the major technical issues in manufacturing is to create an environment to promote collaboration among diverse engineering activities. Collaborative engineering is an innovative approach integrating widely distributed engineering activities through promoting information sharing and actual collaboration. It requires close interactions among developers, suppliers and customers, and consideration of entire product life cycle from concept to disposal. A carefully-designed operating system is crucial for successful collaboration of many different activities in a Networked Virtual Manufacturing System(NVMS). High extensibility, flexibility and efficiency ale the key characteristics requested of an operating system to handle the complexity of the NVMSs. In this paper, we propose a model of the operating system for collaborative engineering using concurrent quasi-procedural method(QPM). QPM is a goal-driven data management technique for distributed and parallel computing environments. It is to be applied to the evaluation of activities to be executed, validities of input data, execution path of activities for a needed output, and expected to greatly improve the productivity of operations by preventing redundant evaluations. Collaboration among many different engineering activities in NVMSs is to be performed by the network of agents that encapsulate the capabilities of both users and their tools.

• 한국안전학회지
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• 제38권1호
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• pp.18-24
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• 2023

Severe natural disasters and man-made attacks such as terrorism are causing unprecedented disruptions in power systems. Due to rapid climate change and the aging of energy infrastructure, both the frequency of failure and the level of damage are expected to increase. Resilience is a concept proposed to respond to extreme disaster events that have a low probability of occurrence but cause enormous damage and is defined as the ability of a system to recover to its original function after a disaster. Resilience is a comprehensive indicator that can include system performance before and after a disaster and focuses on preparing for all possible disaster scenarios and having quick and efficient recovery actions after an incident. Various studies have been conducted to evaluate resilience, but studies on economic damage considering the duration of a power outage are scarce. In this study, we propose an optimal algorithm that can identify failures after an extreme disaster and restore the load on the distribution system through emergency distributed power generation input and system reconfiguration. After that, the cost of power outage damage is analyzed by applying VoLL and CDF according to each restoration strategy.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.463-466
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• 2005

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This new generation technology is linked to a large number of factors like economics and performance, safety and reliability, market regulations, environmental issues, or grid connection constrains. KEPOD (Korea Electric Power Corporation) is performing the project to develope the Distributed Micro Gas Turbine (MGT) technologies by using Swine BID-ENERGY. This paper describes the plans and strategies for the renewable energy of MGT on actual grid-connection under Korean situations. KEPOD also, has a research plan on bio-gas pretreatment system applicable to our domestic swine renewable resources and is performing concept design of pilot plant to test grid operation. In addition, this testing will be conducted in order to respond to a wide variety of needs for application and economic evaluation in the field of On-site generation.

• Smart Structures and Systems
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• 제3권2호
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• pp.147-172
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• 2007

The present paper is concerned with the design of distributed sensors and actuators. Strain type sensors and actuators are considered with their intensity continuously distributed throughout a continuous structure. The sensors measure a weighted average of the strain tensor. As a starting point for their design we introduce the concept of collocated sensors and actuators as well as the so-called natural output. Then we utilize the principle of virtual work for an auxiliary quasi-static problem to assign a mechanical interpretation to the natural output of the sensors to be designed. Therefore, we take the virtual displacements in the principle of virtual work as that part of the displacement in the original problem, which characterizes the deviation from a desired one. We introduce different kinds of distributed sensors, each of them with a mechanical interpretation other than a weighted average of the strain tensor. Additionally, we assign a mechanical interpretation to the collocated actuators as well; for that purpose we use an extended body force analogy. The sensors and actuators are applied to solve the displacement tracking problem for continuous structures; i.e., the problem of enforcing a desired displacement field. We discuss feed forward and feed back control. In the case of feed back control we show that a PD controller can stabilize the continuous system. Finally, a numerical example is presented. A desired deflection of a clamped-clamped beam is tracked by means of feed forward control, feed back control and a combination of the two.

• 한국정밀공학회지
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• 제15권9호
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• pp.82-92
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• 1998

An international standard for the product model data, STEP, and a standard for the distributed object technology, CORBA, will play a very important role in the future manufacturing environment. These two technologies provide background for the sharing of product data and the integration of applications on the network. This paper describes a prototype CAD/CAE environment that is integrated on the network by STEP and CORBA. Several application servers and client software were developed to verify the proposed concept. The present CAD/CAE environments are composed of several individual software components which are not tightly integrated. They also do not utilize the rapidly expanding network and object technologies for the collaboration in the product design process. In the design process in a large organization, sharing of application resources, design data and analysis data through the network will greatly enhance the productivity. The integration between applications can be supported by two key technologies, CORBA(Common Object Request Broker Architecture) and STEP(Standard for the Exchange of Product Model Bata). The CORBA provides interoperability between applications on different machines in heterogeneous distributed environments and seamlessly interconnects distributed object systems. Moreover, if all the data in the CAD/CAE environment are based on the STEP, then we can exclude all the data conversion problems between the application systems.

• 한국군사과학기술학회지
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• 제14권6호
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• pp.1031-1036
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• 2011

In this paper, we have proposed a methodology which can test and evaluate on system level in development phase of command guided missile system. Test and evaluation play a significant role in the development of weapon system, providing the means for determining to what extent the weapon system satisfies its requirements, whether it functions normally in the operational environment. In case of command guided missile having seeker, the missile communications link provides data to allow the missile to fly an efficient trajectory toward target. Therefore, it is very important to test and evaluate for data link between missile and radar on whole system aspect. we introduce the concept and devices for system level test and evaluation of command guided missile system.

• 융합보안논문지
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• 제18권5_2호
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• pp.35-41
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• 2018

육군은 합동개념과 연계하여 지상전장개념을 발전시키고 있으며 이를 지원하기 위해 기반통신체계로서 TICN을 도입하였다. TICN을 이용하여 전송속도의 향상 및 통달거리를 확대하였으며, 이를 통해 감시체계로부터 타격체계까지 실시간 혹은 근실시간으로 정보 유통이 가능하도록 네트워크 중심 작전환경 조성에 힘쓰고 있다. 그러나 TICN은 전장상황에서의 여러 가지 우발상황으로 인해 발생할 수 있는 네트워크 측면에서의 제한사항을 극복하기에는 미흡한 부분이 있다. 이에 본 논문에서는 전장상황에서 발생 가능한 상황에 따른 통신 제한에 대해 파악하고 이를 극복하기 위한 고려사항에 대해 연구하였다.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1995년도 추계학술대회논문집
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• pp.46-55
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• 1995

The multimedia documents becomes the most natural user interface for CSCW(Conputer Supported Cooperative Work) in distributed environment. The objective of this study is to propose a multimedia document architecture and to develop a system that can manage it well. The new architecture is for revisable documents and is the basic layer for hypermedia documents. A good document architecture for CSCW must support pointing, marking, and editing over a part of documents. The user views, version control, and full- content search are also desirable features. In this paper, we discuss the basic concept of a new document architecture for CSCW. We also present the user interfaces for spatio-temporal compositions of multimedia documents.