• Biomedical Science Letters
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• v.5 no.1
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• pp.75-84
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• 1999

In order to study the effects of $\alpha$-tocopherol acetate in glomerular injury, the minimal change nephrosis disease was induced by puromycin aminonucleoside (PAN) in spontaneously hypertensive rats, and we examined biochemical analysis in serum and morphological changes. The experimental animals were divided to control, PAN-treated (30 mg/kg, I.p.), vitamin E-treated (200 mg/kg, P.O.), and PAN+vitamin E-treated groups. After PAN injection, the rate of increase of body weight was lower than the other treatments. In addition, at 8 days after PAN injection, total protein content in serum was the lowest, whereas both blood urea nitrogen and serum creatinine contents were the highest in all experimental groups, which their changes of serum parameters were statistically significant. In morphological changes, the glomerular tissue at 8 days after PAN injection clearly showed obstruction of urinary space and proliferation of mesangial cells, and that loss and fusion of pedicles, vacuolization and edema of endothelial cells, and thickness of basal lamina were ultrastructurally showed in the glomerulus. Glomerular injury was significantly prevented by administration of vitamin E having an antioxidant effect. It suggested that the glomerular injury induced by PAN was accelerated by hypertension, and renal dysfunction might be induced by oxidative injury.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.188-188
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• 2020

우리나라의 대표적인 겨울철 재난인 대설 피해는 대부분 농경지의 비닐하우스에 발생하며, 대표적인 피해종류로는 설압피해, 착설피해 등의 직접피해와 간접피해로 분류라 수 있다. 이 중 가장 피해를 많이 유발하는 것으로 알려져 있는 설압피해는 눈이 쌓인 높이가 높아지며 그 압력으로 인해 비닐하우스가 무너지는 것이다. 눈이 쌒인 높이가 어느 정도 되어야 비닐하우스에 피해를 유발하는지는 지역의 습도나 비닐하우스 설계 기준 등의 지역적이나 환경적인 요인에 따라 달라질 수 있다. 그러므로 본 연구에서는 과거 비닐하우스에 발생한 전국의 피해를 수집하여 지역 특성을 고려하여 온실에 손상을 줄 수 있는 적설심을 분석하였다. 연구의 자료는 행정안전부에서 발행되는 재해연보, 기상청에서 제공되는 적설자료를 사용하였다. 강원도 지역은 대설 연구 자료가 다른 지역에 비해 많기에 최근 대설피해 빈도가 증가하고 있는 충청도, 전라도 지역에 대한 적설심을 분석하였다. 본 연구의 결과로 대비차원 폭설피해 재난관리가 가능한 적설심 기준 설립에 도움을 줄 수 있을 것으로 판단된다.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.6
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• pp.98-104
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• 2015

Excessive thrust acting on the rotor of pump can cause the damage of pump or the decrease of pump lifetime. Therefore, for ensuring the safety of LOX pump of a liquid rocket engine, the thrust of pump rotor is estimated by similarity tests. Axial thrust is indirectly measured by an axial thrust measurement unit positioned outside pump. Radial thrust is calculated based on pressure distribution of volute scroll. As a result, axial and radial thrust are increased when the flowrate of pump decreases. However, both thrusts do not affect the stability of pump rotor since their values are not large.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.28 no.1
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• pp.53-60
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• 2022

Background: The aim of the study is to examine whether mediating or moderating effects of stress between teachers' work environment and work-related musculoskeletal disorders. Methods: Two hundred nine participants took part in the study and completed the surveys including work environment, stress and work-related musculoskeletal disorders questionnaires. Hayes's PROCESS macro was used to test the research models for mediating and moderating effects of stress between work environment with teachers and work-related musculoskeletal disorders. Indirect effect was tested using bootstrapped confidence intervals. Results: The result confirmed that Stress served as a indirect mediator between work environment and work-related musculoskeletal disorders, whereas there was no significant the moderating effect. Conclusion: Stress mediates the relationship between work environment and work-related musculoskeletal disorders. Therefore, it is crucial that teachers' work environment that increases stress should be enhanced to reduce work-related musculoskeletal disorders.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.111-120
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• 2009

This paper presents a fundamental findings of the functional and structural performance of the porous asphalt concrete coated with MMA resin. To evaluate the structural performance, cantabro, wheel tracking, moisture sensitivity and indirect tensile fatigue tests are performed. The tests results show that the cantabro loss is reduced three times and fatigue resistance is significantly increased after the specimens are coated with MMA resin. However there are little changes in the rutting and moisture damage resistances before and after the coating. Air voids, permeability and BPT(British Pendulum Test) tests are conducted to study the functional performance. It is observed form the tests that the air voids and permeability are slightly decreased after the coating. However, the changes in the air voids and permeability are negligible. The skid resistance of the coated specimens is lower than reference specimens. However, the skid resistance is maintained beyond the level of the reference specimens when silica sands are chipped on top of the coated surface.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.145-145
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• 2016

해양환경용 구조물은 극심한 부식 환경에 노출되어 있고 부식손상으로 인한 직간접적 경제적 손실이 발생하고 있는 상황이다. 이에 대한 방식대책으로써 음극방식법이 선박, 교량, 각종 화학장비에 널리 이용되고 있으며, 이러한 산업분야에 가장 흔히 적용되고 있는 음극방식 중 하나가 피방식체에 일정 전류 또는 음극 전위를 인가하는 외부전원법이다. 이는 전도성 부식환경인 해수환경 하에서 철강 및 해양환경용 구조 재료의 내식성을 월등히 향상시킬 수 있기 때문에 설계에 있어서 고급 내식재료 대신 경제적인 상용 재료를 적용할 수 있어 비용 절감효과를 가질 수 있다. 한편 적정 방식전위에서는 부식손상으로부터 강재를 보호하지만, 과방식 전위에서는 취성이 발생함으로써 내구성 감소의 역효과가 나타날 수도 있기 때문에 최적 방식전위의 규명은 반드시 필요하다. 따라서, 본 연구에서는 S355ML강에 대하여 천연해수 용액에서 다양한 정전위를 조건으로 전기화학실험을 실시하여 최적 방식전위를 규명하고자 하였다. 시험편은 에머리 페이퍼로 2000번까지 연마하였고, 아세톤과 증류수로 세척하여 실험하였다. 전기화학(정전위) 실험은 천연해수 속에서 $1.28cm^2$의 면적만을 노출시켜 진행하였으며, OCP로부터 -2.0V까지의 음극분극 곡선을 분석하여 정전위 조건들을 선정하였다. 그리고 외부 직류전원장치를 이용하여 1,200초 동안 다양한 정전위를 인가하였으며, 기준전극은 Ag/AgCl 전극을 이용하였다. 실험 후에는 주사전자현미경과 3D 현미경을 통해 시험편 표면을 관찰하였으며, 그 결과 일부 음극분극 구간에서 강재 표면에 전착물에 의한 뷸균일한 피막이 형성되었다. 또한, 일정 전위구간에서 용해 및 과전압에 대하여 표면손상 정도를 관찰하여, 해수환경 하에서 S355ML강의 최적 방식전위를 규명하였다.

• Journal of agricultural medicine and community health
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• v.33 no.1
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• pp.82-89
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• 2008

Objective:　We compared the prevalence of injury and poisoning in the agricultural and fishery population with that of the general population.Methods: The national health insurance data and agricultufor this study. The age-adjusted standardized morbidity ratio was used to compare the prevalence of all injuries and poisonings of the agricultural and fishery population with that of the general population for the year 2002, as well as the prevalence of certain injuries and poisonings common to the agricultural and fishery population. The age-adjusted standardized morbidity ratio and 95% confidence intervals were attained by using the general population as the standard population group.Results: The age-adjusted standardized morbidity ratio of total injuries and poisonings was significantly high in the agriculture and fishery population. The standardized morbidity ratio was 137.6 in the male agriculture and fishery population and 123.3 in the female agriculture and fishery population. In terms of injuries and poisonings common to the agriculture and fishery population, the age-adjusted standardized morbidity ratio was significantly high regarding the dislocations and strains of lumbar spine/pelvis, shoulder and neck, the fracture of rib/thoracic spine/sternum and pesticide poisoning.Conclusions: The overall prevalence of injury/poisoning was significantly higher in the agriculture and fishery population than in the general population. Various forms of research should be conducted on the injuries of the agriculture and fishery population in the future. In order to compare the differences in the prevalence rates of injuries according to time and region, standard definitions of injuries and occupation related injuries are required.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.2
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• pp.1-15
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• 1997

This paper presents substructural identification methods for the assessment of local damages in complex and large structural systems. For this purpose, an auto-regressive and moving average with stochastic input (ARMAX) model is derived for a substructure to process the measurement data impaired by noises. Using the substructural methods, the number of unknown parameters for each identification can be significantly reduced, hence the convergence and accuracy of estimation can be improved. Secondly, the damage index is defined as the ratio of the current stiffness to the baseline value at each element for the damage assessment. The indirect estimation method was performed using the estimated results from the identification of the system matrices from the substructural identification. To demonstrate the proposed techniques, several simulation and experimental example analyses are carried out for structural models of a 2-span truss structure, a 3-span continuous beam model and 3-story building model. The results indicate that the present substructural identification method and damage estimation methods are effective and efficient for local damage estimation of complex structures.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.5
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• pp.649-656
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• 2015

The protective effect of zinc against cortisol-induced cell injury was examined in rainbow trout gill epithelial cells. Cells exposed to cortisol for 24 h showed increased leakage of lactate dehydrogenase (LDH) as well as decreased cell viability in a dose-dependent manner. Treatment with zinc ($100{\mu}M$ $ZnSO_4$) reduced the severity of both LDH release and cell death as well as protected cells against cortisol-induced caspase-3 activation, indicating reduction of apoptosis. Cortisol-induced cell death, leakage of LDH, and caspase-3 activation were blocked by the glucocorticoid receptor antagonist Mifepristone (RU-486), suggesting that cell injury was cortisol-dependent. In addition, we studied the effect of zinc on the expression of antioxidant genes such as metallothionein A (MTA), metallothionein B (MTB), glutathione-S-transferase (GST), and glucose-6-phosphate dehydrogenase (G6PD) during cortisol-induced cell injury. MTA, MTB, GST, and G6PD mRNA levels increased after treatment with zinc or cortisol, separately or in combination. Higher mRNA levels of MTA, MTB, GST, and G6PD were detected when cells were treated with $100{\mu}M$ $ZnSO_4$ and $1{\mu}M$ cortisol in combination at the same time compared to treatment with zinc or cortisol separately. Cells treated with zinc showed increased intracellular free zinc concentrations, and this response was significantly enhanced in cells treated with cortisol and zinc. In conclusion, zinc treatment inhibited cortisol-induced cytotoxicity and apoptosis through indirect antioxidant action.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.2
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• pp.39-45
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• 2024

The residual alveolar ridge below the denture base undergoes physiologic changes over time, which results in the existing dentures becoming less accurate with the residual alveolar ridge. In addition, changes of the occlusal plane, decreasing in vertical dimension and loss of denture retention and facial support can occur. Consequently, denture relining may be required to accommodate these changes and ensure an ongoing close fit. Relining a denture can be performed directly on the chairside using autopolymerizing relining materials or indirectly in the laboratory using heat-cured relining materials. A direct relining method is not only simple but also time and cost effective. However, irritation or burning sensation of the mucosa can occur, and poor bonding of the relining material to the denture base can be cited as disadvantages. The indirect relining method exhibits relatively high bonding strength between the relining material and the denture base, but the patient might experience discomfort during relining process period. This report will examine the characteristics of relining materials, including those used in the relining of CAD-CAM dentures, and explore the clinical considerations for relining procedures.