• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.683-686
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• 2007

This paper investigates acoustical characteristics of open-type ceilings using 1:25 scale model. The field survey in the existing 15 halls was carried out to figure out the ceiling structure. The components of the open-type ceiling were mainly steel truss structures, duct, catwalk and finishing surfaces. In order to investigate the absorption characteristics of the equipped ceiling, the absorption coefficient measurements were made using 1:25 reverberation chamber based on ISO 354. Results showed that the absorption coefficient of the empty ceiling structure (6m-height) with 50%-perforated covering plate was 0.2-0.3 at above 500 Hz. When steel structure was added inside the empty ceiling, absorption coefficient increased by 0.16 at 250-1kHz. Adding catwalk did not increase the absorption, but adding duct increased the absorption at 1-2kHz. NRC of the equipped ceiling was 0.39, and the absorption characteristics were mainly found at high frequencies. In addition, the opening size of the covering plate did not change the absorption coefficient of the equipped ceiling meaningfully.

• 한국콘텐츠학회논문지
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• 제16권10호
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• pp.382-392
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• 2016

본 연구는 복합적 구조의 자기주도학습 과정을 구성하고, 이를 토대로 대학생들을 위한 복합적 구조의 자기주도학습 측정 도구를 개발하는 것을 목적으로 하였다. 연구 목적을 달성하기 위해 문헌 분석 및 선행 연구 검토를 통해서 동기와 학습실행 행동(학습목표 설정, 학습 계획 수립, 학습 활동, 학습결과 평가 행동)과 학습관리 행동(자기관찰, 자기검토, 자기수정)이 복합적으로 구성된 자기주도학습 모형을 구성하였다. 이를 토대로 19개의 하위요인을 구성하였고, 114개 측정 문항을 개발하였다. 먼저 예비 척도를 개발하여 수도권의 D대학 학생 128명을 대상으로 신뢰도 검증을 수행하였다. 그 결과 모든 하위 요인의 신뢰도가 양호한 것으로 나타나 제외된 문항 없이 본 척도를 개발하였다. 본 척도의 타당성을 검증하기 위해 수도권의 D대학 학생 674명을 대상으로 신뢰도와 구인타당도를 검증하였다. 신뢰도는 목표행동 (.834), 목표관찰(.809), 목표검토(.839), 목표수정(.773), 계획행동(.765), 계획관찰(.861), 계획검토(.890), 계획수정(.810), 학습전략(.784), 학습관리(.775), 학습유지(.809), 자원획득(.828), 학습관찰(.846), 학습검토(.827), 학습수정(.830), 평가행동(.892), 평가관찰(.866), 평가검토(.891), 평가수정(.868)로서 모든 하위 요인이 양호한 것으로 나타났다. 구인타당도 검증을 위해 확인적 요인분석을 실시한 결과 최초 모형은 적합한 것으로 나타나지 않았다. 이에 모형 수정지수를 고려하여 1차 수정한 결과 ${\chi}^2$(563.254), CFI=.963, NFI=.951, RMSEA=.064로 나타나 모형이 타당한 것으로 검증되었다.

• 콘크리트학회지
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• 제8권2호
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• pp.139-150
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• 1996

본 연구의 목적은 프리캐스트 콘크리트(PC) 대형판 구조물의 축소모델 제작 및 실험기법에 관한 정보을 제공하는 것이다. 적용된 축소율은 1/5이며, 4가지의 실험이 수행되었다. : 모델 콘크리트와 모델 철근의 재료실험, 수평접합부의 압축실험, 수직접합부의 전단실험, 2층 부분구조물의 정적 주기 실험, 이들 실험결과를 기초로 다음의 결론을 도출하였다. : (1)모델 콘크리트는 일반적으로 예상보다 압축강도가 크게 나타났다. (2)모델 철근은 진공관을 사용하지 않고 열처리를 할 경우 연성의 저하를 보인다. (3)수평접합부와 수직접합부의 파괴모드는 실물크기와 모델이 거의 유사하였으나. 모델의 강도는 상사법칙에 의한 요구강도보다 크게 나타났다. (4) 실물크기와 유사하게 모델철근의 연성과 모델 콘크리트의 압축강도를 확보할 수 있다면, 1/5모델 부분구조물의 이력거동은 실물크리와 매우 근접되게 나타낼 수 있다.

• Journal of Preventive Medicine and Public Health
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• 제57권3호
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• pp.279-287
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• 2024

Objectives: This study validated the Vietnamese version of the Disaster Adaptation and Resilience Scale (DARS) for use in vulnerable communities in Vietnam. Methods: This was a cross-sectional study involving 595 adults from 2 identified communities. The original DARS assessment tool was translated, and the validity and reliability of the Vietnamese version of DARS (V-DARS) were assessed. The internal consistency of the overall scale and its subscales was evaluated using Cronbach's alpha and McDonald's omega reliability coefficients. Confirmatory factor analysis (CFA) was employed to evaluate its construct validity, building upon the factor structure identified in exploratory factor analysis (EFA). Construct validity was assessed based on convergent and discriminant validity. Results: Following the established criteria for EFA, 8 items were removed, resulting in a refined V-DARS structure comprising 35 items distributed across 5 distinct factors. Both alpha and omega reliability coefficients indicated strong internal consistency for the overall scale (α=0.963, ω=0.963) and for each of the 5 sub-scales (all>0.80). The CFA model also retained the 5-factor structure with 35 items. The model fit indices showed acceptable values (RMSEA: 0.072; CFI: 0.912; TLI: 0.904; chi-square test: <0.01). Additionally, the convergent and discriminant validity of the V-DARS were deemed appropriate and satisfactory for explaining the measurement structure. Conclusions: Our findings suggest that the V-DARS is a valid and reliable scale for use within vulnerable communities in Vietnam to assess adaptive responses to natural disasters. It may also be considered for use in other populations.

• Corrosion Science and Technology
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• 제3권3호
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• pp.87-97
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• 2004

This paper presents a new approach with meso scale structure models to express mechanical property, such as stress - strain relationships, of concrete. This approach is successful to represent both uniaxial tension and uniaxial compression stress - strain relationship, which is in macro scale. The meso scale approach is also applied to predict degraded mechanical properties of frost-damaged concrete. The degradation of mechanical properties with frost-damaged concrete was carefully observed. Strength and stiffness in both tension and compression decrease with freezing and thawing cycles (FTC), while stress-free crack opening in tension softening increases. First attempt shows that the numerical simulation can express the experimentally observed degradation by introducing changes in the meso scale structure in concrete, which are assumed based on observed damages in the concrete subjected to FTC. At the end applicability of the meso scale approach to prediction of the degradation by combined effects of salt attack and FTC is discussed. It is shown that clarification of effects of frost damage in concrete on corrosion progress and on crack development in the damaged cover concrete due to corrosion is one of the issues for which the meso scale approach is useful.

• 한국해안해양공학회지
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• 제12권2호
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• pp.96-106
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• 2000

최근에까지 대형구조물이 해양공간이용의 목적으로 외해공항 및 해양터미날로 건설되어 왔다 그러나 때로는 이와같은 큰 규모의 구조물은 파량에 대해 현저한 벽으로 작용하게 되고 해안에 심각한 침식현상을 야기하게 된다 본 연구는 해안선으로부터 각기 다른 거리에 외해구조물을 건설할 때에 해저지형변화를 다룬 것으로 일련의 3차원 이동상실험으로 상세히 조사하였다 또한 해빈류와 외해구조물 배후의 국소침식과의 관계를 분명하게 하기 위하여 수리모델실험과 같은 규격으로 Boussinesq방정식 모델로 해빈류를 계산하고 비교하였다.

• 대한교통학회지
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• 제19권6호
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• pp.131-142
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• 2001

Previous OD matrix estimation methods from link traffic counts have focused on the formulation of mathematical model and its solution algorithm. Thereby those methods have assumed that true or real OD is similar to the target OD and paid little attention to the properties of the change of OD structure. Although it is general situation that each OD pair increases or decreases due to significant land use and to large time variation between target OD with real OD, those methods have set unrealistic assumptions that target OD increases or decreases uniformly and that the OD structure does not change. Therefore those methods have showed poor performance of OD estimation in general situation. To cope with the problem. this paper suggests a new concept of OD matrix structure and shows the shortcomings of previous method′s dependancy on target OD matrix. We divide "OD trips" into "OD scale" and "OD structure". Where OD scale is a quantitative magnitude of OD trips and "OD structure" is ordinal OD scale. This paper use the same solution algorithm developed by Baek et al. (2000) for analysing the OD structure. Results of numerical examples show that the performance of the method is better than that of previous methods, while the previous methods have better performance in estimation only when OD trips increase or decrease. In addition to, if OD structure does not change, the results show that the error of estimation is low relatively regardless of the large difference of trips between target OD and real OD. This paper also shows that the model performance on OD structure and on OD trips is low as the number of origins that OD structure is changed increase. From the results we suggest that the change of OD structure can be more important information than the difference between target OD and real OD in OD estimation steps.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.163-173
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• 1997

This article presents an application of a large-scale structural mixing model (Broadwell et al. 1984) to the blowout of turbulent reacting jets discharging perpendicularly into an unconfined cross air-flow. In an analysis of a common stability curve, a plausible explanation can be made that the phenomenon of blowout is related only to the mixing time scale of the two flows. The most notable observation is that the blowout distance is traced at fixed positions at all times according to the velocity ratio R. Measurements of the lower blowout limits in the liftable flame agree qualitatively with the blowout parameter ${\varepsilon}$, proposed by Broadwell et al. Good agreement between the results calculated by a modified blowout parameter ${\varepsilon}^'$ and experimental results confirms the important effect of a large-scale structure in specifying the stabilization feature of blowouts.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.195-200
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• 2007

System identification of real-scale structure is performed using forced vibration test. There exist various techniques available for identifying the dynamic characteristis of structures using dynamic and static measurements. In this study, The finite element(FE) model of the structure is analytically constructed using ANSYS and the model was updated using the results experimentally measured by the forced vibration test. forced vibration tests showed that Hybrid Mass Damper induced floor responses coincided with the earthquake induced ones which was numerically calculated based on the updated FE model.

• Structural Engineering and Mechanics
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• 제61권2호
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• pp.267-274
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• 2017

In this study was investigated of possibility using the recorded micro tremor data on ground level as ambient vibration input excitation data for investigation and application Operational Modal Analysis (OMA) on the bench-scale earthquake simulator (The Quanser Shake Table) for model steel structures. As known OMA methods (such as EFDD, SSI and so on) are supposed to deal with the ambient responses. For this purpose, analytical and experimental modal analysis of a model steel structure for dynamic characteristics was evaluated. 3D Finite element model of the building was evaluated for the model steel structure based on the design drawing. Ambient excitation was provided by shake table from the recorded micro tremor ambient vibration data on ground level. Enhanced Frequency Domain Decomposition is used for the output only modal identification. From this study, best correlation is found between mode shapes. Natural frequencies and analytical frequencies in average (only) 2.8% are differences.