• 제목/요약/키워드: 외부평가

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A conceptual design of a conduction-cooled magnet for a superconducting property measurement system (초전도 특성평가장치용 전도냉각 마그네트의 개념설계)

  • Choi, Suk-Kin;Bae, Jun-Han;Sohn, Myung-Hwan;Sim, Ki-Deok;Kim, Woo-Seok;Lee, Ji-Kwang;Park, Chan;Lee, Sang-Jin;Choi, Kyeong-Dal
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.812-813
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    • 2008
  • 본 연구에서는 외부인가 자장을 위한 초전도 특성평가장 치용 레이스트랙형 초전도 마그네트의 개념설계를 하였다. 초전도 특성 평가장치는 외부인가 자장과 온도를 변화시켜가며 고온 초전도 선재의 특성을 측정할 수 있는 장치이다. 초전도 전력기기가 응용될 수 있는 온도범위인 $10K{\sim}77K$ 온도범위에서 초전도 선재의 특성을 평가하기 위해서 약 20cm 정도 길이의 시편이 차지하는 공간이 필요하고 이 공간에 1% 이하의 자장균일도와 최소 3T 이상을 가지는 마그네트가 필요하다. 이러한 조건을 만족시키는 초전도 마그네트는 필연적으로 레이스트랙형 마그네트를 가지는 split형이어야 한다. DI-BSCCO H type과 HT type 두 가지 선재에 대한 전자장 해석을 통하여 제한조건을 만족시키는 마그네트 설계를 하였다. 이렇게 설계된 초전도 마그네트는 초전도 특성평가장치 제작에 활용될 것이다.

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Design of SERO Note System Model Using Collective Intelligence and Just-In-Time Learning (집단지성과 적시학습을 이용한 SERO 노트 시스템 모형 설계)

  • Ha, Jin-Seok;Kim, Chang-Suk
    • Journal of the Korean Institute of Intelligent Systems
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    • v.22 no.5
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    • pp.590-596
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    • 2012
  • This paper proposes SERO note system which supports collaborative learning between teachers and learners by using the learner's internal and external environment information. The proposed system defines the learner's internal environment depending on desire for relearning assessment questions, and the learner's external environment depending on a percentage of correct answers. The purpose of educational evaluation through SERO typing of each question is reflected in collaborative learning between teachers and learners. As the results of SERO typing of each question are accumulated on DB and used, a variety of feedback chances can be offered to teachers and learners.

New Statistical Pattern Recognition Technology for Condition Assessment of Cable-stayed Bridge on Earthquake Load (지진하중을 받는 사장교의 상태평가를 위한 새로운 통계적 패턴 인식 기술)

  • Heo, Gwanghee;Kim, Chunggil
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.3
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    • pp.747-754
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    • 2014
  • In spite of its usefulness for health monitoring of structures on steady external load, the statistical pattern recognition technology (SPRT), based on Mahalanobis distance theory (MDT), is not good enough for the health monitoring of structures on large variability external load like earthquake. Damage is usually determined by the difference between the average measured value of undamaged structure and the measure value of damaged one. So when external variability gets larger, the difference gets bigger along, which is thus easily mistaken for a damage. This paper aims to overcome the problem and develop an improved Mahalanobis distance theory (IMDT), that is, a SPRT with revised MDT in order to decrease external variability so that we will be able to continue to monitor the structure on uncertain external variability. This method is experimentally tested to see if it precisely evaluates the health of a cable-stayed bridge on each general random load and earthquake load. As a result, the IMDT is found to be valid in locating structural damage made by damaged cables by means of data from undamaged cables. So it is proved to be effectively applicable to the health monitoring of bridges on external load of variability.

Development of Fracture Energy Measurement System of Asphalt Mixture Using Marshall Tester (마샬 안정도시험기를 이용한 아스팔트 혼합물의 파괴에너지 측정시스템 개발)

  • Kim, Boo-Il;Lee, Moon-Sup
    • International Journal of Highway Engineering
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    • v.11 no.1
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    • pp.135-144
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    • 2009
  • The purpose of this study is to develop a simple and rational crack evaluation system using Marshall tester. Fracture energy were used as a parameter to evaluate the crack resistance of asphalt mixtures. Marshall tester basically measures the vertical deformation obtained from the linear variable differential transformer(LVDT) attached on the specimen's exterior, which can cause a measurement error due to the local deformation near the loading head. Therefore, the validity of the measurement system of Marshall tester should be tested to use it in calculation of fracture energy. Two types of indirect tensile strength tests were performed using four types of asphalt mixtures at two temperature conditions. From the tests, it was shown that local deformation near the loading head had not occurred before a specimen was fractured, so that it did not cause the measurement error of fracture energy. And also from the statistic analysis, the coefficient of variation of vertical deformation measurements obtained on specimen's exterior is less than 15%. Thus, vertical deformation measurements obtained on the specimen's exterior can be used in crack evaluation system using Marshall tester.

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