• Magazine of the Korea Concrete Institute
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• v.9 no.6
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• pp.147-156
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• 1997

지금까지 국내에서는 콘크리트의 크리프에 관한 실험적 연구가 많이 진행되지 못하여 해당 구조물의 설계기술 도입국의 규준에 따라 크리프를 예측해왔다. 그러나 예측된 크리프 모델이 국내 콘크리트 재료의 특성에 적합한지에 대한 실험적 검증은 제대로 이루어지지 않고 있는 실정이다. 본 연구에서는 국내에서 프리스트레스 콘크리트 구조물에 적용하는 실용 고강도 콘크리트의 크리프 값을 예측하기 위해 동일한 설계기준강도를 갖는 세 가지 배합에 대하여 재령별로 크리프 시험을 수행하고 이 실험결과를 ACI, CEB/FIB, KSCE, JSCE규준들의 크리프 예측식과 비교 분석하였다.시험결과와 이들규준들에 대한 비교분석에 의하면 CEB/FIB-90 크리프 예측식은 비교적 과대 평가되고 ACI 209-92와 JSCE-96의 경우는 과소 평가되었으나 콘크리트 표준시방서 KSCE -96 크리프 예측식은 비교적 시험결과에 근접하는 것으로 평가되었다. 그러나 구성재료의 양적 변동에 '따른 배합별 시험결과의 차이를 반영할 수 있는 점이 보완되어야 할 것으로 보며 향후 많은 실험결과를 바탕으로 국내에서 생산되는 콘크리트에 대하여 보다 정확히 크리프를 예측할 수 있는 연구가 필요하다.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2011-2013
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• 2004

본 논문은 그루빙(grooving),타이닝(tinning),텍스쳐(texture) 등의 포장 도로의 표면 상태를 고성능의 레이저 변위센서를 사용하여 정밀하게 측정하고, 측정한 표면 상태를 객관적으로 평가하는 장비 개발에 관한 논문이다. 본 논문에서는 실제 평가 장비 차량을 만들기에 앞서 전체 시스템을 설계하고, 실내에서 차량과 도로의 모사 장비를 만들어 실험하였다. 본 실험에서는 오실로스코프와 DAQ (Data Aquisition) 보드를 사용하였다. LabView로 선호처리 프로그래밍을 하여 컴퓨터 화면에 GUI 형태로 나타내었다. 측정 데이터는 컴퓨터의 저장 공간에 저장하여 후처리를 가능하게 하였다. 또한, 실제 평가 장비 차량에 장착하게 될, GPS(Global Positioning System) 시스템으로 부터 실시간으로 평가 장비 차량의 이동거리 데이터를 얻었다. 실험 결과 차량이 80km/h로 주행할 때 도로 표면 타이닝의 폭과 깊이가 평균 9.67% 오차를 보였으며, 이동거리는 0.03% 이내의 오차를 보여 만족할 만한 결과를 얻었다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.57-58
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• 2012

위성항법중앙사무소는 다수의 DGNSS 기준국을 운영하고 있으며, 이 중 일부 기준국은 타 기준국에 비해 TEQC 품질평가 결과가 저조하다. 이에 이 연구는 TEQC 품질평가가 상대적으로 불량한 충주기준국을 대상으로 비교실험을 수행한다. 이전에 다른 관측장비를 이용하여 수행한 동시 관측에서는 TEQC 품질평가가 다른 기준국과 유사한 수준으로 나타나 지형이나 전파방해 등과 같은 주변 환경적인 요인은 아닌 것으로 확인하였다. 이번 충주비교실험은 기존 설치된 관측장비의 이상유무를 고려하여 크게 세 부분으로 나누어 진행한다. 안테나 이상판단은 기존 관측기기에 다른 기종의 안테나로 교체하여 확인하고, 수신기 이상 유무는 분배기를 이용하여 두 수신기에 동시 관측값을 기록하여 판단한다. 마지막으로 케이블의 경우, 상위 두 실험을 통해 수집된 관측자료의 품질평가를 통해 확인 가능하다. 이 연구를 통하여 TEQC 품질평가 저하요인을 확인하고 개선방안을 제시하여 양질의 DGNSS 정보를 제공할 수 있을 것으로 판단된다.

• The Journal of the Korea Contents Association
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• v.2 no.1
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• pp.59-67
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• 2002

This study pre-processed the characters, performed the feature extraction for the beauty evaluation, and then defined the similarity function. It suggested the definition of the similarity function, and the extraction of the features of character elements. it experimented how much the various input character patterns were similar with the standard character patterns, found their results were almost similar with the expected ones and the results of beauty evaluation on general people through the questionaire with the results of the methods suggested here.

• Journal of The Korean Association For Science Education
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• v.40 no.5
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• pp.515-529
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• 2020

'Scientific inquiry experiments', which was newly created subjects in the 2015 revised curriculum, was expected in the aspect of learning science and developing core competences through science practices. Based on changed view of evaluation, assessments of a practice-centered subject 'Scientific inquiry experiments' should be try to conducted in various ways, but many challenges were reported. In this study, through analysis of current status of assessment of the subject, we intended to find the way of conducting and supporting 'Scientific inquiry experiments'. We collected assessment materials and explanatory description about them from 25 teachers who taught 'Scientific inquiry experiments' in 2018 and 2019. And we analyzed the cases with framework which were consisted with three main categories: elements, standards, methods of assessments. Also, we investigated how the results of assessment were utilized. For the validity, we requested verification of the results of our data analysis to experts of science education and science teachers. From them, we also collected their opinions about our analysis. As a result of the study, teachers assessed some elements of inquiry skills such as 'analysis and interpreting the data', 'conducting inquiry' more than others which were closely related to what subject-matter the teachers used to organized inquiry program with. In the aspect of domain of assessments, though cognitive domain and affective domain as well as skills were evaluated, we also found that the assessment of those domains had some limitation. In terms of standard of assessment, the goals of assessment were presented in most cases, but there were relatively few cases which had the specific criteria and the stepwise statements of expected performance of students. The time and subject of the assessment were mainly post-class and teachers, and others such as in-class assessments, peer-assessments were used only in specific contexts. In all cases, the results of assessments used for calculating students' grade, but in some cases, we could observe that the results used for improving teaching and feedback for students. Based on these results, we discussed how to support the assessments of 'Scientific inquiry experiments'.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.579-588
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• 2015

The data model for structural experiment information formally organizes the information involved in the structural experiments before the data repository using the data model is implemented. The data model is particularly required for the data repositories for the large-scale structural experiment information and the general information for various types of experiments, such as the NEEShub Project Warehouse developed by NEES. This paper proposes criteria for evaluating the organization and the use of design model for structural experiment information. The term of AVE(attribute value existence) indicates the ratio of attributes who values exist in objects, and then used for defining the Attribute AVE for the use of an attribute, the Class AVE for a class, the Class Level AVE for a class including its lower-level classes, the Project AVE for a project including all classes at class levels, and the Data Model AVE for a data model including projects. These criteria are applied to the projects in the NEES data model, and it is successively possible to numerically describe the evaluation of the use of classes and attributes in the data model.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.6
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• pp.33-43
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• 2010

This paper deals with the hybrid structural test technique which has been introduced and studied currently in Korea. In this study, a Mini-MOST system which was developed as a part of NEES research was modified and improved to reduce the total simulation time to half of the original system. Using the proposed system together with the 2 dimensional small steel frame specimen, the validity and efficiency of the hybrid test technique is investigated. Even though the hybrid test has been developed as an alternative to the shaking table test and has been studied and applied for a long time in several countries, no attempt has been made to compare it directly with the shaking table test. Therefore, in this study, the hybrid test results are compared with those of the shaking table test as well as with a numerical simulation for the verification of hybrid test. From the comparison and analysis of the test results, it is concluded that the hybrid test can simulate the actual seismic behavior of structural systems very accurately and it can be a good alternative to the shaking table test.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1D
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• pp.33-39
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• 2012

More and more pavements are suffering from damage these days due to the below-zero winter temperatures and frequent snowfalls. From this research, the freeze-thawing mechanisms of pavements will be observed, and the freeze-thawing resistance of porous asphalt concrete mixture is to be evaluated according to various assessment methods. The investigation was conducted through applying rigid and flexible pavements to freeze-thawing resistance experiments, which include various experiments such as deformation rate measurements, Lottman tests, repeated cyclic freeze-thawing experiments, stripping resistance tests and so on. Test results revealed that the porous asphalt concrete had less deformations according to temperatures compared to dense-graded asphalt concrete due to the 20% void gap. In addition, according to the freeze-thawing repetition experiments which are effected by moisture, the porous asphalt concrete mixture showed superior resistance to repeated cyclic freeze-thawing compared to other asphalt concrete mixtures due to the drainage and the voids within the specimen.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.310-316
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• 2020

In this study, the stability and EMP shielding performance of metal-based industrial by-products aggregates with excellent conductivity and easy procurement to be used as concrete aggregates for EMP shielding are evaluated. The industrial by-products are electronic-arc-furnace oxidizing slag, copper smelting slag, and ferro-moldibdenum. The composition analysis of aggregates and aggregate stability are evaluated. As a result of the experiment, ferro-moldibdenum is shown to have l ow stability as an aggregate due to its high Free-CaO. The remaining aggregates are evaluated to be safe to use as aggregates for concrete. In addition, industrial by-products aggreagate-specimens excluding ferro-moldibdenum are shown higher compressive strength than the plain specimen. The recycle aggregates, electronic-arc-furnace oxidizing slag and copper smelting slag, are shown excellent EMP shielding performance, the EMP shielding performance is expected to increase if the average particle diameter of the aggregate is small or evenly distributed.

• Journal of Korean Society of Steel Construction
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• v.20 no.4
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• pp.483-491
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• 2008

There has been much focus on the strong axis steel moment connections after the Northridge earthquake in 1994. However, research studieson the seismic behavior of weak axis moment connections could be hardly found despite the fact that these connection details have been frequently used as seismic details of MRF in Korea. Therefore, the objective of this research is to provide better knowledge on the seismic behavior of weak-axis steel moment connections, which can be widely applicable to many structures with similar characteristics. For this purpose, an experimental program was designed and performed with twotypes of weak-axis steel moment connections, namely the bracket type and WUF-B type, based on the survey of existing field data and literatures. Using the experimental results obtained from the quasi-static cyclic testing of these specimens, structural performances of the joints such as hysteretic curves, maximum strength capacities and the strain of reinforced bars were investigated. From the test results, the bracket-type connection was shown to have more than a 5% story drift capacity, compared with the WUF-B type connection's 4%. These specimens were also shown to have higher strength capacities than the nominal design strength. The bracket-type connection showed a slow strength degradation after maximum strength was researched. However,the WUF-B type connection showed a rapid strength degradation that caused brittle behavior.