• Steel and Composite Structures
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• 제19권2호
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• pp.385-403
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• 2015

This paper presents the status improvement of an old damaged deck type rural road steel truss bridge through the modal parametric study after partial retrofitting. The dynamic and static tests on bridge were carried out as in damaged state and after partial retrofitting. The dynamic testing on the steel bridge was carried out using accelerometers under similar environmental conditions with same speed of the moving vehicle. The comparison of the modal parameters i.e., frequency, mode shape mode shape curvature, modal strain energy, along with the deflection parameter are studied with respect to structural analytical model parameters. The status up gradation for the upper and downstream truss obtained was different due to differential level of damage in the bridge. Also after retrofitting the structural elemental behavior obtained was not same as desired. The damage level obtained through static tests carried out using total station indicated further retrofitting requirement.

• Nutrition Research and Practice
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• 제11권3호
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• pp.214-222
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• 2017

BACKGROUND/OBJECTIVES: Glutathione S-transferase (GST) forms a multigene family of phase II detoxification enzymes which are involved in the detoxification of xenobiotics by conjugating substances with glutathione. The aim of this study is to assess the antioxidative status and the degree of DNA damage in the subclinical hypertensive patients in Korea using glutathione S-transferase polymorphisms. SUBJECTS/METHODS: We examined whether DNA damage and antioxidative status show a difference between GSTM1 or GSTT1 genotype in 227 newly diagnosed, untreated (systolic blood pressure $(BP){\geq}130mmHg$ or diastolic $BP{\geq}85mmHg$) subclinical hypertensive patients and 130 normotensive subjects (systolic BP < 120 mmHg and diastolic BP < 80 mmHg). From the blood of the subjects, the degree of the DNA damage in lymphocyte, the activities of erythrocyte superoxide dismutase, the catalase, and the glutathione peroxidase, the level of glutathione, plasma total radical-trapping antioxidant potential (TRAP), anti-oxidative vitamins, as well as plasma lipid profiles and conjugated diene (CD) were analyzed. RESULTS: Of the 227 subjects studied, 68.3% were GSTM1 null genotype and 66.5% were GSTT1 null genotype. GSTM1 null genotype had an increased risk of hypertension (OR: 2.104, CI: 1.38-3.35), but no significant association in GSTT1 null genotype (OR 0.982, CI: 0.62-1.55). No difference in erythrocyte activities of superoxide dismutase, catalase, or glutathione peroxidase, and plasma TRAP, CD, lipid profiles, and GSH levels were observed between GSTM1 or GSTT1 genotype. Plasma levels of ${\alpha}-tocopherol$ increased significantly in GSTT1 wild genotype (P < 0.05); however, plasma level of ${\beta}-carotene$ increased significantly in GSTT1 null genotype (P < 0.01). DNA damage assessed by the Comet assay was significantly higher in GSTM1 null genotype than wild genotype (P < 0.05). CONCLUSIONS: These results confirm the association between GSTM1 null genotype and risk of hypertension as they suggest that GSTM1 null genotype leads to an increased oxidative stress compared with wild genotype.

• 한국지반환경공학회 논문집
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• 제18권1호
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• pp.49-58
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• 2017

국내 한랭지역(강원권)의 경우 낮은 연평균 기온에 의한 도로터널 라이닝 내구성에 문제가 발생하게 된다. 이에 따라 라이닝에 균열, 망상균열, 박락, 박리, 누수 등의 문제가 발생하며, 해마다 경제적 손실 및 인명피해가 증가하고 있는 실정이다. 하지만 국내에서는 기온에 따른 도로터널 라이닝의 피해에 대한 연구는 미비한 상태이다. 따라서, 본 논문에서는 한랭지(강원권) 터널 70개를 조사함으로써 현재 한랭지역의 피해현황을 분석하였고, 같은 한랭지역 중 비교적 따뜻한 기온을 가지는 강릉 지역과 기온이 낮은 홍천 지역의 터널 라이닝 피해를 비교함으로써 기온이 도로터널 라이닝에 미치는 영향을 분석하였다.

• The Korean Journal of Ecology
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• 제21권2호
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• pp.117-124
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• 1998

To clarify the effects of acid precipitates on histological damage, water status, and growth of Pinus densiflora green house experiment applyin simulated acid rain was carried out. Contact angle of water droplet on needles of P. densiflora seedlings treated with simulated acid rain of different pHs simulated acid rain was, the more rapid transpiration was. Leaf water potential after water withdrawal was also reduced rapidly in proportion to acidity of simulated acid rain. Height growth of P. densiflora seedlings treated with simulated acid rain of pH 2 decreased, while growth of seedlings treated with that of pH 3 and 4 increased comparing with that treated with normal rain of pH 5.6. pH of cultivated soil in pH 2 plot was acidified with the amount of simulated acid rain applied but that in pH 3 and 4 plots did not show any directional change. From those results, it could be interpreted that decrease of height growth in pH 2 plot was originated from multiple effects of water deficit from rapid transpiration and soil acidification. On the other hand, increased of height growth in pH 3 and 4 plots would be originated from the supply of N and S included in simulated acid rain.

• 한국구조물진단유지관리공학회지
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• 제18권3호
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• pp.12-17
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• 2014

• Structural Engineering and Mechanics
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• 제44권4호
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• pp.417-429
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• 2012

Taking the superficial temperature increment as the major fatigue damage indicator, the infrared thermography was used to predict fatigue parameters (fatigue strength and S-N curve) of welded joints subjected to fatigue loading with a high mean stress, showing good predictions. The fatigue damage status, related to safety evaluation, was tightly correlated with the temperature field evolution of the hot-spot zone on the specimen surface. An energetic damage model, based on the energy accumulation, was developed to evaluate the residual fatigue life of the welded specimens undergoing cyclic loading, and a good agreement was presented. It is concluded that the infrared thermography can not only well predict the fatigue behavior of welded joints, but also can play an important role in health detection of structures subjected to mechanical loading.

• Earthquakes and Structures
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• 제16권2호
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• pp.197-208
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• 2019

The objective of this study is to propose new seismic intensity parameters based on the Hilbert spectrum and to associate them with the seismic damage potential. In recent years the assessment of even more seismic features derived from the seismic acceleration time-histories was associated with the structural damage. For a better insight into the complex seismic acceleration time-history, Hilbert-Huang Transform (HHT) analysis is utilized for its processing, and the Hilbert spectrum is obtained. New proposed seismic intensity parameters based on the Hilbert spectrum are derived. The aim is to achieve a significant estimation of the seismic damage potential on structures from the proposed new intensity parameters confirmed by statistical methods. Park-Ang overall structural damage index is used to describe the postseismic damage status of structures. Thus, a set of recorded seismic accelerograms from all over the word is applied on a reinforced concrete frame structure, and the Park-Ang indices through nonlinear dynamic analysis are provided and considered subsequently as reference numerical values. Conventional seismic parameters, with well-known seismic structural damage interrelation, are evaluated for the same set of excitations. Statistical procedures, namely correlation study and multilinear regression analysis, are applied on the set of the conventional parameters and the set of proposed new parameters separately, to confirm their interrelation with the seismic structural damage. The regression models are used for the evaluation of the structural damage indices for every set of parameters, respectively. The predicted numerical values of the structural damage indices evaluated from the two sets of seismic intensity parameters are inter-compared with the reference values. The numerical results confirm the ability of the proposed Hilbert spectrum based new seismic intensity parameters to approximate the postseismic structural damage with a smaller Standard Error of Estimation than this accomplished of the conventional ones.

• 한국지진공학회논문집
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• 제13권2호
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• pp.47-58
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• 2009

본 연구에서는 변전소 시스템의 지진취약도 분석을 수행하여 변전소에 대한 지진취약도 함수를 제시하였다. 변전소는 여러 개의 설비와 구조물이 복합적으로 구성되어 있는 시스템이므로 각 설비에 대한 지진취약도 분석을 수행하여 이를 바탕으로 고장수목을 작성하여 변전소 전체의 파괴확률을 산정함으로써 변전소에 대한 지진취약도 평가를 수행하였다. 이를 위하여 국내 변전소의 현황을 파악하여 지진피해추정을 위한 변전소의 분류형식을 결정하였으며, 결정된 대표변전소 형식에 대한 평가대상 기기를 선정하였다. 대표 변전소 형식으로는 765kV, 345kV, 154kV 변전소의 GIS형 변전소로 결정하였다. 각 변전소의 취약도 검토대상 기기로는 변압기와 절연 애자를 선택하였다. 각 변전소의 변압기와 절연애자의 파괴모드와 파괴기준을 설정하여 지진취약도 곡선을 도출하였다. 최종적으로 변전소에 대한 고장수목을 이용하여 각 기기의 지진취약도 곡선으로부터 변전소 전체의 파괴확률을 산정하여 정의된 손상상태별 변전소의 지진취약도 함수를 산정하였다.

• 한국환경성돌연변이발암원학회:학술대회논문집
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• 한국환경성돌연변이발암원학회 2003년도 추계학술대회
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• pp.176-176
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• 2003

• Earthquakes and Structures
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• 제24권6호
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• pp.429-437
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• 2023

This paper studied the prediction of structural damage indices to buildings after earthquake occurrence using Multiple Linear Regression (MLR) and Fuzzy Linear Regression (FLR) methods. Particularly, the structural damage degree, represented by the Maximum Inter Story Drift Ratio (MISDR), is an essential factor that ensures the safety of the building. Thus, the seismic response of a steel building was evaluated, utilizing 65 seismic accelerograms as input signals. Among the several response quantities, the focus is on the MISDR, which expresses the postseismic damage status. Using MLR and FLR methods and comparing the outputs with the corresponding evaluated by nonlinear dynamic analyses, it was concluded that the FLR method had the most accurate prediction results in contrast to the MLR method. A blind prediction applying a set of another 10 artificial accelerograms also examined the model's effectiveness. The results revealed that the use of the FLR method had the smallest average percentage error level for every set of applied accelerograms, and thus it is a suitable modeling tool in earthquake engineering.