• 전기학회논문지P
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• 제60권1호
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• pp.32-36
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• 2011

In this study, authors have proposed the autonomous state estimation which has been composed with IEC61850, GPS time synchronization and objective model design concept. The proposed method is able to supervise/correct measurement and communication error from SCADA. The major advantages of the proposed autonomous state estimation are that it is possible to evaluate integrity of data measured and transferred from SCADA, to reduce human intervention and to expense national-size applications such as EMS (Energy Management System), WAMS (Wide Area Monitoring System) or WAPS (Wide Area Protection System). This study addresses the issues related to the operation of the smart grid and proposes a new automated approach to achieve this goal. Through applying the proposed system to IEEE 14-bus test electric system, we prove the possibility of the proposed idea.

• 한국소음진동공학회논문집
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• 제13권2호
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• pp.92-98
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• 2003

A rate gyroscope has been used popularly to measure the angular motion of a given vehicle using a symmetric rotor spinning rapidly about its symmetry axis. Since the rapid rotation is required in this type of gyroscope, the motor has been used to make the rotor spin, so that it results in a heavy configuration. The toning-fork gyroscope has been developed to avoid this problem, which utilizes a Coriolis coupling term and vibration about one axis. Due to the Coriolis effect, the vibration of one axis is transferred to other axis when the angular motion along the vibrating axis is given to the system. The concept of a tuning-fork gyroscope was recently realized using MEMS techniques. However, the dynamic characteristics of the tuning-fork gyroscope has not been discussed in detail. In this study. we derived the equations of motion for the tuning-fork type gyroscope using the energy approach and investigated the dynamic characteristics by means of numerical analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.247-252
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• 2002

A rate gyroscope has been used popularly to measure the angular motion of a given vehicle using a symmetric rotor spinning rapidly about its symmetry axis. Since the rapid rotation is required in this type of gyroscope, the motor has been used to make the rotor spin, so that it results in a heavy configuration. The tuning-fork gyroscope has been developed to avoid this problem, which utilizes a coriolis coupling term and vibration about one axis. Because of the coriolis effect, the vibration of one axis is transferred to other axis when the angular motion along the vibrating axis is given to the system. The concept of a tuning-fork gyroscope was recently realized using MEMS techniques. However, the dynamic characteristics of the tuning-fork gyroscope has not been discussed in detail. In this study, we derived the equations of motion for the tuning-fork type gyroscope using the energy approach and investigated the dynamic characteristics by means of numerical analysis.

• 한국소음진동공학회논문집
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• 제16권5호
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• pp.521-528
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• 2006

The vibration fatigue is suitable case of fatigue problem that system is exposed to the random or other irregular sources. Even some kinds of effort using power spectral density (PSD) and statistical concept was presented to cope with the intangible force signal, it is still lack of providing a reasonable solution when its exciting frequency is near or beyond of first eigenvalue. In this paper, energy approach method is presented to calculate a vibration induced fatigue damage in frequency domain. Since the corresponding damage become much larger than nominal case when the vibration is coupled with a mode shape of given structure, the new technique compensate the characteristics of structure with a measured frequency response function (FRF) between forcing acceleration and responding stress.

• 전산구조공학
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• 제5권2호
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• pp.119-127
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• 1992

변형영화(strain-softening)현상을 보이는 철근 콘크리트 구조물의 실제 파괴 발생시까지의 거동을 해석하기 위하여 변위제어법을 사용하고, 해석결과의 신뢰도가 떨어지지 않으면서도 해석 수행시간을 줄이기 위하여 기존의 층상화 방법과 비층상화 방법의 장점을 조합한 새로운 기법에 의하여 구조물의 해석을 실시하였다. 또한 선택된 요소의 크기에 따라 해석결과가 다르게 나타나는 현상을 보정해 주기 위한 방법으로 파괴 에너지의 개념을 도입하여 단면의 변형도 분포를 바꾸어 주는 방식을 제안하였으며, 이에 의한 해석을 실시하여 실험치와 비교하였다.

• 전기학회논문지
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• 제64권11호
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• pp.1611-1617
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• 2015

This paper presents an effective approach for establishing countermeasures against voltage sags based on the concept of area of severity. In order to apply preventive measures against faults such as lightning arrester, overhead earth wires and so on, it is important to find optimal points for installing the preventive measures. The optimal points can be determined by the calculation of the area of severity(AOS) to voltage sags and the expected sag frequency per unit length of line. In this paper, an effective method to find optimal points to apply countermeasures against voltage sags is addressed with case studies.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.46-63
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• 2012

The concept of an "intelligent building" received significant attention from academic, industry and standard development organizations when technically termed a building management system (BMS). Wireless sensor networks (WSNs) and their recent development enhanced monitoring and control applications for the building's areas. This paper surveys and analyzes advantages of the main current and emerging approaches that may be fit for BMS. Specifically, we discuss challenges including interoperability, integration, overhead, and bandwidth limitation of WSNs in BMS. Based on analyses, we highlight the advantages of an IP-based and RESTful architecture approach as the most suitable solution for BMS using WSNs (BMS-WSN). The paper also describes our future direction and design for BMS-WSN based on these advantages. The purpose is to enable interaction of users with BMS-WSN in the same way as with any website while ensuring energy efficiency. A test-bed implementation and evaluation of a BMS application is also introduced in this paper to demonstrate the feasibility and benefits of IP-based and RESTful architecture for BMS.

• 대한건축학회논문집:구조계
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• 제34권6호
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• pp.11-18
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• 2018

Isogeometric concept is introduced to find out the optimum layout of plane structure under free vibration. Eigenvalue problem is formulated and numerically solved in order to obtain natural frequencies and mode shapes of plane structures. For the exact geometric expression of the structure, the Non-Uniform Rational B-spline Surface (NURBS) basis functions is employed and it is also used to define the material density functions. A node-wise design variables is adopted to deal with the updating of material density in topology optimization (TO). The definition of modal strain energy is employed to achieve the maximization of fundamental frequency through its minimization. The verification of the proposed TO technique is performed by a series of benchmark test for plane structures.

• 한국수소및신에너지학회논문집
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• 제26권3호
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• pp.294-299
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• 2015

Free piston linear engine (FPLE) is a promising concept being explored in the mid-20th century. On the other hand, Arficial neural networks (ANNs) are non-linear computer algorithms and can model the behavior of complicated non-linear processes. Some researchers already studied this method to predict internal combustion engine characteristics. However, no investigation to predict the performance of a FPLE using ANN approach appears to have been published in the literature to date. In this study, the ability of an artificial neural network model, using a back propagation learning algorithm has been used to predict the in-cylinder pressure, frequency, maximum stroke length of a free piston linear engine. It is advised that, well-trained neural network models can provide fast and consistent results, making it an easy-to-use tool in preliminary studies for such thermal engineering problems.

• 한국조경학회지
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• 제27권3호
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• pp.69-79
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• 1999

Recently, new concept and paradigm of 'Environmentally-Friendless' is taking a growing interest in environmental planning and design. This study is to develop the new approach of sustainable development, and to establish the indicators for environmentally-friendliness of "Tourism Farms" in rural areas. A questionnaire survey was conducted for deputy manager group and expert group. The environmentally-friendliness of tourism farms is composed of three categories, conservation of global environment(Low Impact), friendliness to surrounding nature(High Contact), and environmental health and amenities (Health '||'&'||' Amenity). Four indicators, such as saving of energy and water resource, reduction and reuse of garbage, natural purification of sewage disposal, and utilization of natural energy, were affecting the first category, i.e., conservation of global environment(Low Impact). And, friendliness to surrounding nature (High Contact) is affected by 3 indicators, such as contact to nature and diverse green areas, water intimate '||'&'||' contact areas, and natural ecology observation by biotope. Finally, the dimension of environmental health and amenity is affected by 3 indicators, such as nature affinity by farming experience, environmental-friendliness of soil '||'&'||' crops by organic farming, campaign and education programs of environmentally-friendliness. From the result of Importance-Performance Analysis(IPA) for 10 indicators, environmentally-friendliness was recommended as 'Concentrate Here'. And, the content validity of 10 indicators for 3 categories was examined by factor analysis. The result showed as the same as hypothetical model, which proved the validity of hypothetical model.