• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.630-634
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• 2004

A new three phase three-level Pulse Width Modulation (PWM) Switched Voltage Source (SVS) inverter with zero neutral point potential is proposed. The major advantage is that the peak value of the phase output voltage is twice as high as that of the conventional neutral-point-clamped (NPC) PWM inverter. Furthermore, three-level waveforms of the proposed inverter can be achieved without switch voltage unbalance problem. Since the average neutral point potential of the proposed inverter is zero, the common ground between input stage and output stage is possible. The proposed inverter is verified by experimental results based on a laboratory prototype.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2004년도 하계학술대회
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• pp.219-222
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• 2004

정보통신설비 접지의 기본적인 방법은 각 설비에 대한 접지계통간에 아무런 접속이 되지 않는 것이다. 이것을 독립접지라고 하는데 이렇게 할 경우에 어느 한 접지체로의 이상전류 유입에 따른 대지전위 상승에 의하여 다른 접지체에 상승유도전압(rising potential)이 걸려 해당 설비에 손상을 입힐 수 있으므로 각 접지체 간에 적절한 이격거리를 확보해 주어야 한다. 그러나 설치공간상의 제약을 받게 되므로 때로는 접지계통간에 접속시켜 등전위화를 이룸으로써 이상전류 유입에 따른 영향을 배제할 수 있다. 이것을 공통접지라고 하는데 일본의 기술 영향을 받은 우리나라는 오랜 동안 독립접지 방식이 안정된 방법으로 인식해와 공통접지에 대한 우려를 가지고 있다. 그러나 최근에는 ITU-T의 접지 관련 표준화 활동에서 중요한 역할을 수행하고 일본에게 있어서도 독립접지로서 수용할 수 없는 현실적 환경 문제의 개선을 위하여 통신센터빌딩등에 적용할 수 있는 통합적인 공통접지 시스템 기술을 개발하고 있다.

• 한국해양공학회지
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• 제16권6호
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• pp.37-43
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• 2002

The calculation of earthwork plays a major role in the plan or design phase of many civil engineering projects, such as seashore reclamation; and thus, it has become very important to improve upon its accuracy. There have been common drawbacks to earlier methods of ground profiling, such as dialing with sharp corners or the grid points of any tow straight lines. In this paper, we prepose an algorithm for finding a terrain surface using the natural boundary conditions and the both direction spline method, which interpolates the given three-dimensional data by using spline. As a result of this study, the algorithm of the proposed two methods to estimate pit excavation volume should provide a better accuracy than Spot height, Chambers, Chen, or Lin method. Also, the mathematical model mentioned offers maximum accuracy in estimating the volume of a pit excavation.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.427-439
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• 2003

A previous study evaluated the seismic response of typical multi-span simply supported (MSSS) and multi-span continuous (MSC) steel-girder bridges in the central and southeastern United States. The results showed that the bridges were vulnerable to damage resulting from impact between decks, and large ductility demands on nonductile columns. Furthermore, fixed and expansion bearings were likely to fail during strong ground motion. In this paper, several retrofit measures to improve the seismic performance of typical multi-span simply supported and multi-span continuous steel girder bridges are evaluated, including the use of elastomeric bearings, lead-rubber bearings, and restrainer cables. It is determined that lead-rubber bearings are the most effective retrofit measure for reducing the seismic vulnerability of typical bridges. While isolation provided by elastomeric bearings limits the forces into the columns, the added flexibility results in pounding between decks in the MSSS steel-girder bridge. Restrainer cables, which are becoming a common retrofit measure, are only moderately effective in reducing the seismic vulnerability of MSSS and MSC steel girder bridges.

• Journal of Plant Biology
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• 제13권1호
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• pp.47-55
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• 1970

In order to approach a reasonable method for the indirect estimation of the productivity in terrestrial plants, allometric method was studied with herbs, such as Boenmeria frutescens and Hibiscus mutabilis, and scrubs, such as Robinia pseud oacacia and Morus alba f. Hchiroe. Allometric relations between D230H, square of the stem(or shoot) diameter(D30) on 30cm height above ground multiplied by stem length(H), and the amount of the stem(Ws), orof the leaves per stem, were fitted to each material plant with linear regression. The allometric coefficient in relation of D230H to Ws was approximated between scrubs having different life form, and the allometric function in relation of DF2 to WL was common between herbs in spite of having different growth habitat. As the allometries between D230H and Ws or WL were changeable with the seasonal change it funciton should be calculated repeatedly whenever investigating the standing crop of such community. It is able to utilize an indirect value of D30 obtained from the allometry between D30 and H because direct measurement of D30 in the field is accompanied by troublesome and waste of much time.

• 대한치과의사협회지
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• 제55권10호
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• pp.733-737
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• 2017

Successful osseo-integration of dental implants that Dr. Bronemak reported in 1965 had been ground-breaking research in the restorative dentistry for the missing dentition. Clinical application of dental implants in the restorative dentistry has begun with the role of retention and support for the complete denture, beyond the functional recovery in partially missing area, and succeeds in the cosmetic recovery for anterior missing area. Recently, immediate implantation and loading after the extraction have been preferred by many excellent clinicians especially on maxillary anterior missing area, because they want to prevent from the absorption of residual alveolar bone. But it is hard to decide immediate loading for common clinicians also, because it is difficult for them to convict proper osseo-integration. In this article, immediate implantation and delayed loading case on maxillay anterior region have been introduced and predictable prosthetic procedure for the esthetic result has suggested.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.278-282
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• 2003

The rapid growth of wireless and mobile communications has stimulated the development of multilayer filter technology. In this paper, one type of aperture-coupled microstrip interdigital-loop resonators in a multilayer structure are proposed and investigated for the applications to the design of a new class of compact microstrip bandpass filter. The new filter configuration consists of two arrays of microstrip interdigital-loop resonators that can be coupled through the apertures on the common ground plane. Depending on the arrangement of the apertures, different filtering characteristics can easily be realized. The results of measurement are almost similar to those of simulation.

• Earthquakes and Structures
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• 제4권5호
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• pp.527-555
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• 2013

This paper proposes probabilistic models for estimating the seismic demands on reinforced concrete (RC) bridges with base isolation. The models consider the shear and deformation demands on the bridge columns and the deformation demand on the isolation devices. An experimental design is used to generate a population of bridges based on the AASHTO LRFD Bridge Design Specifications (AASHTO 2007) and the Caltrans' Seismic Design Criteria (Caltrans 1999). Ground motion records are used for time history analysis of each bridge to develop probabilistic models that are practical and are able to account for the uncertainties and biases in the current, common deterministic model. As application of the developed probabilistic models, a simple method is provided to determine the fragility of bridges. This work facilitates the reliability-based design for this type of bridges and contributes to the transition from limit state design to performance-based design.

• Structural Engineering and Mechanics
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• 제75권2호
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• pp.145-155
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• 2020

This paper investigates the influence of spatial varations of accidental mass eccentricities on the torsional response of inelastic multistorey reinforced concrete buildings. It complements recent studies on the elastic response of structural buildings and extends the investigation into the inelastic range, with the aim of providing guidelines for minimising the torsional response of structural buildings. Four spatial mass eccentricity configurations of common nine story buildings, along with their reversed mass eccentricities subjected to the Erzincan-1992 and Kobe-1995 ground motions were investigated, and the results are discussed in the context of the structural response of the no eccentricity models. It is demonstrated that when the initial linear response is practically translational, it is maintained into the inelastic phase of deformation as long as the strength assignment of the lateral resisting bents is based on a planar static analysis where the applied lateral loads simulate the first mode of vibration of the uncoupled structure.

• 한국환경생물학회:학술대회논문집
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• 한국환경생물학회 2002년도 학술대회
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• pp.119-122
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• 2002

Soil contaminants are common in industrialized sites, They can affect directly soil and indirectly ground water and food. Soil mutagens and carcinogens are of great interest due to their potentially hazardous effects on human health. The aim of this study was to monitor the genotoxicity of contaminated soils, Soil leachates were collected from two polluted sites and one control site in Cheongju. Tradescantia BNL 4430 clone was used as experimental matierials. Chromosomal damages induced by soil leachates were detected by the Tradescantia-micronucleus assay. It is known from the result that Tradescantia-micronucleus assay is an excellent botanical tool for detection of biological risk due to environmental toxicants.