• Title/Summary/Keyword: 지내력

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Seismic Retrofit of Existing RC Structure Using Hysteretic Dampers (이력댐퍼를 이용한 기존 RC구조물의 내진보강)

  • Choe, Seon-Yeong
    • Computational Structural Engineering
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    • v.26 no.2
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    • pp.37-42
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    • 2013
  • 준공 후 상당한 시간이 지나 내진설계가 되지 않았거나 내진상세가 이루어지지 않은 건물의 부족한 내진성능을 보완하기 위한 방법의 하나로 좌굴이 제한된 가새형 댐퍼를 적용할 수 있다. 이 방법을 적용할 경우, 기존 내진보강법의 불확실성을 줄일 수 있었음에도 불구하고, 댐퍼의 설계과정이 복잡하여 실무에 적용하기 어려웠다. 그러나 본 원고에서는 강성과 강도개념을 적용한 댐퍼의 설계법을 적용함으로써, 실무에서 쉽게 적용할 수 있도록 하였다. 준공된 지 16년이 지난 비틀림 비정형 건물에 대한 내진성능을 평가한 후, 가새형 댐퍼로 보강한 결과는 다음과 같다. (1) 일방향해석결과 나타난 골조별 하중-지붕변위의 관계를 이용하여, 연약골조의 강성을 강한 골조의 강성과 일치시키고, 이 강성비로부터 댐퍼가 부담하는 최적의 내력비율을 정하여 내진보강을 수행한 결과, 가새를 설치한 방향으로는 가새형댐퍼가 비틀림 방지와 연성증대효과를 구조물에 부여하여 성능이 획기적으로 증가하였다. 또한, 그 가새의 직각방향 하중에 대해서도 가새를 설치함으로써 비틀림 강성이 증가하고, 가새와 코어벽체가 인장과 압축으로 횡력에 저항하여 횡저항 성능이 증가하였다. (2) 내진성능이 부족한 비틀림 비정형 건물의 내진성능을 증진시키기 위해 가새형 댐퍼를 적용함에 있어, 댐퍼의 강성을 이용하여 구조체의 비틀림 거동을 최소화하고, 연성을 증진시키는 방법을 체택할 경우, 실무자들이 보다 쉽게 적용할 수 있으면서 그 효과도 상당히 클 것으로 기대된다.

A study on the Development of the Shell-type Pole Transformer Using the Zig-Zag Winding (Zig-Zag 귄선에 의한 내철형 주상변압기 개발에 관한 연구)

  • Min, Yun-Hong;Shin, Dae-Chul
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.8
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    • pp.121-128
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    • 2007
  • In this thesis, we would show how to lay out and produce the shell-type transformer using the world's first Zig-Zag winding way, instead of a general winding. Also, we omit the progress of varnish-impregnation, so that we could develop the new shell-type transformer winding which improves the short-circuit characteristics and dielectric strength. It has a copernican effect to reduce the thickness and the number of insulation papers, as compared with a general winding transformer. We would prove that it is far superior in cost reduction, loss reduction, and mechanical force of short-circuit. And eventually you must find it useful in the pole transformer for power distribution in the domestic power companies.

The Study of Improvement Effect of Ground Settlements and Bearing Capacity by Stone Columns (스톤컬럼 공법의 지내력 증진 효과에 대한 연구)

  • Park, Sang-Kook;Lee, Song
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.4
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    • pp.123-132
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    • 2008
  • Aseries of in-situ tests and ground water level measurements with stone and slug materials had been conducted to find out effect of ground settlement reduction and bearing capacity improvement by the Stone Column method. As the result of the tests, it was proved that the Stone Column method is effective for reduction of ground settlement and improvement of bearing capacity. In addition the ground water level went down without overburden load. These results show that the Stone Column method is effective for an increase in density and resistance to liquefaction. The results of estimation of ground settlement and bearing capacity by general theoretical equation, it show that the Stone Column method increases bearing capacity by 2.7~5.7 times and decreases ground settlement by 2~3.5 times.

Design of Load and Strain Measuring Equipment Using Strain Gage, Instrumental Differential Amplifier and A/D Converter in a Truss System (스트레인 게이지 계측용 차동 증폭기와 A/D 변환기를 이용한 트러스 구조물의 내력 측정 장치 설계)

  • Baek, Tae-Hyun;Lee, Byung-Hee
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.2
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    • pp.217-224
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    • 2008
  • Trusses are found in many common structures such as bridges and buildings. The truss is a fundamental design element in engineering structures and it is important for an engineer to apply the truss design to engineering structures by understanding the mechanics of truss element. In an experimental course, the experiment selves as an example of the usefulness of the Wheatstone bridge in amplifying the output of a transducer. With the apparatus described here, it is possible to obtain experimental measurements of forces in a truss member which agree within errors to predictions from elementary mechanics. The apparatus is inexpensive, easy to operate, and suitable as either a classroom demonstration or student laboratory experiment. This device is a small table-top experiment. The conventional strain measuring device is costly and complicated - it is not simple to understand its structure. Hence, strain gage and the A/D converter are assembled to come up with a load and a strain measuring device. The device was tested for measuring the strain in a loaded specimen and the results were compared to those predicted by theory of mechanics.

A Research for Computation of Bearing Capacity and Settlement of Foundation Considering Scale Effect in Weathered-granite Layer (화강풍화토에서 Scale Effect를 고려한 기초의 지지력 및 침하량 산정에 관한 연구)

  • 박용부;정형식
    • Journal of the Korean Geotechnical Society
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    • v.20 no.1
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    • pp.131-139
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    • 2004
  • When calculating bearing capacity and settlement of actual foundation from plate test result fur design and construction of shallow foundation, scale effect should be considered. But, adequate guide and test result of scale effect were not prepared yet in Korea. So, to analyze the relations of bearing capacity and settlement as the difference of loading plate sizes, model test and field loading test were performed with different loading plate on weathered-granite layer. Model tests were conducted with water content, compaction number, saturated unit weight and plate size(Dl5, 25cm) in soil-box$(2,000\times 2,000\times 1,000mm)$ formed soil layer. Field loading tests were carried out with diameters of loading plate$(D15, 25, 30, 40, 75\times 75, 140\times 210cm)$ on the same soil condition. Finally, we presented the prediction formula of bearing and settlement for computating scale offset in design of shallow foundation through result analysis of load test and numerical simulation on weathered soil and rock.

Analysis on the Dielectric Characteristics of Various Insulation Gases for Developing a Sub-cooled Liquid Nitrogen Cooling System (과냉질소 냉각시스템 가압용 기체의 절연내력특성 분석)

  • Kang, H.;Ko, T.K.
    • Progress in Superconductivity and Cryogenics
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    • v.13 no.1
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    • pp.27-30
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    • 2011
  • A sub-cooled liquid nitrogen cooling system is known as a most promising method to develop large scale superconducting apparatuses such as superconducting fault current limiters and superconducting cables [1]. Gaseous helium (GHe), gaseous nitrogen ($GN_2$) and sulfur hexafluoride ($SF_6$) are commonly used for designing an high voltage applied superconducting device as an injection gaseous medium [2, 3]. In this paper, the analysis on the dielectric characteristics of GHe, $GN_2$ and $SF_6$ are conducted by designing and manufacturing sphere-to-plane electrode systems. The AC withstand voltage experiments on the various gaseous insulation media are carried out and the results are analyzed by using finite element method (FEM) considering field utilization factors (${\xi}$). It is found that the electric field intensity at sparkover ($E_{MAX}$) of insulation media exponentially decreases according to ${\xi}$ increases. Also, the empirical expressions of the functional relations between $E_{MAX}$ and ${\xi}$ of insulation media are deduced by dielectric experiments and computational analyses. It is expected that the electrical insulation design of applied superconducting devices could be performed by using the deduced empirical formulae without dielectric experiments.

Experimental Study on Temporary Overvoltage Characteristics of MOV Based Surge Protective Devices (MOV 기반 서지보호기의 일시과전압 특성에 대한 실험적 연구)

  • Shim, Hae-Sup;Jeon, Tae-Hyun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.1
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    • pp.71-77
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    • 2010
  • Protection against lightning surge is an essential part of almost any electrical and electronic equipment today. Metal Oxide Varistor(MOV) is the single most important component in the overwhelming majority of the Surge Protective Devices(SPD) designated to provide such protection. In this paperr various types of MOV based SPD are inspected and experiments are carried out on the side effects of the low Measured Limiting Voltage(MLV) characteristics. Experiment results show that a lower MLV could cause a higher Temporary Overvoltage(TOV)-induced SPD failure rate in the field, and SPD are more likely to be victims rather than protectors in a TOV scenario. This means that from a safety perspective, the SPD should be specified with higher TOV withstand capability(UT) and faster SPD disconnector.

Breakdown Characteristics of a Model Power Line in the Presence of Combustion Flame (연소화염 존재 시 모델 전력선의 절연파괴 특성)

  • Kim, In-Sik
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.10
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    • pp.164-171
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    • 2006
  • The results of an experimental investigation into the breakdown characteristics of a model power line in the presence of oil flame are reported under the application of 60[Hz] ac and dc high-voltages. It is appeared that flame can reduce by more than half, 80[%] in maximum, the breakdown voltage with the case of h=0 under ac and dc applications. Taking a horizontal model line with a k=0.5 of flame position, it can be seen from the results that the reduction of flashover levels, in comparison with the no-flame case, are 78.6[%] for h=0[cm], 59.7[%] for h=3[cm], 46.9[%] for h=6[cm], 41.5[%] for h=9[cm] and 35.4[%] for h=12[cm] when ac voltage is applied.

Permanent Basement Wall Convergence Method Using a PHC Pile (PHC 파일을 이용한 영구벽체 융합 공법)

  • Ryu, Soo-Hyun
    • Journal of the Korea Convergence Society
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    • v.6 no.6
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    • pp.163-169
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    • 2015
  • This study was intended to suggest a new-concept construction method of permanent basement wall combined with earth retaining wall by using PHC piles to overcome the disadvantages of conventional CIP methods or the like which have been used just for earth retaining walls during field construction, and to determine its applicability. PHC piles are characterized by the reliable quality attributed to prefabrication (shop fabrication) as well as superior concrete strength and prestressing steel strength to that of CIP in the aspect of materials, and also higher bending moment than that of CIP in the aspect of structure.

Thermal Conductivity and Dielectric Strength Measurement of the Impregnating Materials for the Next Generation Winding Type Superconducting Fault Current Limiter (차세대권선형한류기를 위한 함침용 재료의 열전도도 및 절연 내력 측정)

  • Yang Seong Eun;Bae Duck Kweon;Ahn Min Cheol;Kang Hyoung Ku;Seok Bok Yeol;Chang Ho Myung;Kim Sang Hyun;Ko Tae Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.7 no.1
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    • pp.42-46
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    • 2005
  • The resistive type high temperature superconducting fault current limiter (HTSFCL) limits the fault current using the resistance generated by fault current. The generated resistance by fault current makes large pulse power which makes the operation of HTSFCL unstable. So, the cryogenic cooling system of the resistive type HTSFCL must diffuse and eliminate the pulse energy very quickly. Although the best way is to make wide direct contact area between HTS winding and coolant as much as possible, HTS winding also needs the impregnation layer which fixes and protects it from electromagnetic force. This paper deals with the thermal conductivity and dielectric strength of some epoxy compounds for the impregnation of high temperature superconducting (HTS) winding in liquid nitrogen. The measured data can be used in the optimal design of impregnation for HTS winding. Aluminar filling increased the thermal conductivity of epoxy compounds. Hardener also affected the thermal and electric characteristic of epoxy compounds.