• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.826-829
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• 2004

Structural Dynamics Modification is very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material property, changing shape of structure. In this research, using the surface grooving technique, shape of base structure was changed to improve its first natural frequency. Utilizing the result of frequency variation analysis, groove shape was formed gathering the many small embossing elements. For this process, Criterion Factor was introduced. To reduce its amount of calculation, the range of target area was restricted to their neighboring area and initial grooving point was selected using high-strain energy. This surface grooving technique was successfully applied to the HDD cover model.

• Earthquakes and Structures
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• 제16권1호
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• pp.29-39
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• 2019

A three-step screening process is presented in this article for selection of consistent earthquake records in which number of suitable ground motions is quickly screened and reduced to a handful number. Records that remain at the end of this screening process considerably reduce the dispersion of structural responses. Then, an effective method is presented for spectral matching and modification of the selected records. Dispersion of structural responses is explored using different statistical measures for each scaling procedure. It is shown that the Uniform Design Method, presented in this study for scaling of earthquake records, results in most cases in the least dispersion measure.

• Earthquakes and Structures
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• 제7권5호
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• pp.891-906
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• 2014

The purpose of this study is to propose a modification factor to reflect the lateral stiffness modification when a step is located in flat plates. Reinforced concrete slabs with steps have different structural characteristics that are demonstrated by a series of structural experiment and nonlinear analyses. The corner at the step is weak and flexible, and the associated rotational stiffness degradation at the corner of the step is identified through analyses of 6 types of models using a nonlinear finite element program. Then a systematic analysis of stiffness changes is performed using a linear finite element procedure along with rotational springs. The lateral stiffness of reinforced concrete flat plates with steps is mainly affected by the step length, location, thickness and height. Therefore, a single modification factor for each of these variables is obtained, while other variables are constrained. When multiple variables are considered, each single modification factor is multiplied by the other. Such a method is verified by a comparative analysis. Finally, a complex modification factor can be applied to the existing effective slab width.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.100-105
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• 1996

This paper proposes the method of experimental structural dynamic modification of fixture for environmental vibration test control. This method can predict the responses at any points on fixture utilizing the experimental data, and structural dynamic modification of fixture is made using the predicted responses for the spectra at the speciment attachment points to meet the specified reference spectrum. From the results of controlling the fixture before and after modification by conventional control method and optimal reference spectrum, which has been previously reported by the authors, the proposed method is shown to be an effective one.

• 한국구조물진단유지관리공학회 논문집
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• 제1권1호
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• pp.53-64
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• 1997

Recently, safety evaluation of structures has received great concern in this country. One major problem in safety evaluation is that the results are often quite different depending upon evaluation authority. This is mainly due to arbitrary selection of various modification factors when employing allowable stress method for safety evaluation, The purpose of the present study is, therefore, to establish a rational method to determine the modification factors, especially the stress modification factor and the deterioration modification factor based on visual examination. It is thought that the proposed method yields a rational and consistent result for safety evaluation and may efficiently be used for realistic evaluation of load capacity of bridge structures.

• 한국자기공명학회논문지
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• 제23권3호
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• pp.67-72
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• 2019

Caveolae are small plasma membrane invaginations that play many roles in signal transduction, endocytosis, mechanoprotection, lipid metabolism. The most important protein in caveolae is the integral membrane protein, caveolin, which is divided into three families such as caveolin 1, caveolin 2, and caveolin 3. Caveolin 1 and 3 are known to incorporate palmitate through linkage to three cysteine residues. Regulation of the protein palmitoylation cycle is important for the cellular processes such as intracellular localization of the target protein, membrane association, conformation, protein-protein interaction, and activity. However, the detailed aspect of individual palmitoylation has not been studied. In the present work, the role of each lipid modification at three cysteines was studied by NMR. Our results suggest that each lipid modification at the natively palmitoylation site has its own roles. For example, lipidations to C106 and C129 are play a role in structural stabilization, however, interestingly, lipid modification to C116 interrupts the structural stabilization.

• 한국건설관리학회논문집
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• 제6권3호
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• pp.72-80
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• 2005

최근 재건축에 대한 규제가 강화됨에 따라 리모델링에 대한 관심이 높아지고 있는 추세이며, 기존 아파트의 경우에도 발코니 확장 등을 목적으로 내력벽을 철거하는 등 아파트 평면에 대한 변경사례가 증가하고 있다. 그러나 이와 같은 평면변경에는 구조안전에 대한 검토가 반드시 수반되어야 함에도 불구하고 이에 대한 인식은 크게 부족하며, 리모델링과 관련한 기존의 연구도 대부분 경제성 향상 측면에 초점을 맞추고 있어 구조적 안전성 측면에서의 연구는 부족한 실정이다. 이에 본 연구에서는 최근 진행되고 있는 리모델링 사례 및 국내 대형 건설사들의 아파트 평면분석을 통해 아파트 평면변경에 수반되는 평면변경요소를 추출하고 이의 적용에 따른 구조요소별 응력변화 영향을 분석하였다. 분석 결과, 벽체축력은 독립 벽체를 제거하였을 때, 슬래브 모멘트는 ㄱ자형 벽체를 맞닿은 수직벽체와 함께 제거하였을 때 가장 불리한 결과를 초래하는 것으로 나타났다. 본 연구의 결과는 리모델링이나 발코니 확장 등 평면변경을 목적으로 벽체를 제거함으로 인해 유발되는 벽체와 슬래브의 응력변화를 예측하고 평가하는데 활용할 수 있을 것으로 기대된다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.96-99
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• 2008

When the design modification is occurred, at present, design process based on 2-D spend more time and effort than that based on 3-D to modify related structural details. To improve and develop these processes, therefore, the design possibility of civil structures based on virtual model of 3-D must be investigated. We designed reinforced concrete pier of 3-D model, containing parameters. The parameters was defined as structural details like area of the section, reinforcement specification for design modification and structural analysis. In this paper, we researched about the processes modeling of reinforced concrete bridge pier based on parameters, the extracting data from the virtual model of 3-D, and the reflection of data to virtual model throughout structural analysis.

• 한국전산구조공학회논문집
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• 제26권1호
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• pp.49-57
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• 2013

일반교량은 상부구조, 연결부분, 하부구조 및 기초로 구성되어 있고 내진성능은 하부구조와 연결부분의 파괴메카니즘에 의해 결정된다. 그러므로 내진설계는 구조부재의 설계강도, 즉 설계단면을 결정하는 기본설계단계에서 수행되어야 한다. 도로교설계기준 내진설계편은 두 가지 기본설계 방식을 제시하고 있다. 첫째는 기존 설계방식으로 내진설계편이 제시한 응답수정계수를 적용하는 방식이고 둘째는 새로 도입된 연성도 내진설계 방식으로 설계자가 응답수정계수를 결정하는 방식이다. 이 연구에서는 일반교량을 대상으로 두 설계방식을 같이 적용하는 기본설계를 수행하고 내진성능 확보의 관점에서 요구되는 보완사항을 제시하였다.

• Structural Monitoring and Maintenance
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• 제6권1호
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• pp.33-46
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• 2019

In present study, Operational Modal Analysis (OMA) was employed to carry out the dynamic and vibration analysis of the threshing unit of the combine harvester thresher as a mechanical component. The main study is to find the causes of vibration and to decrease it to enhance the lifetime and efficiency of the threshing unit. By utilizing OMA, structural modal parameters such as mode shapes, natural frequencies, and damping ratio was calculated. The combine harvester was excited by engine to vibrate different parts and accelerometer sensor collected acceleration signals at different speeds, and OMA was utilized by nonparametric and frequency analysis methods to obtain modal parameters while vibrating in real working conditions. Afterwards, finite element model was designed from the thresher and updated using the data obtained from the modal analysis. Using the conducted analyses, it was specified that proximity of the thresher pass frequency to one of the natural frequencies (16.64 Hz) was the most important effect of vibration in the thresher. Modification process of the structure was carried out by increasing mass required for changing the natural frequency location of the first mode to 12.4 Hz in order to reduce resonance and vibration of the thresher.