• Computers and Concrete
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• 제4권2호
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• pp.101-117
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• 2007

A new model predicting the nonlinear basic creep behaviour of concrete structures subjected to high multi-axial stresses is proposed. It combines a model based on the thermodynamic framework of the elasto-plastic continuum damage theory for time-independent material behaviour and a rheological model describing phenomenologically the long-term delayed deformation. Strength increase due to ageing is regarded. The general 3D solution for the creep theory is derived from a rate-type form of the uniaxial formulation by the assumption of associated creep flow and a theorem of energy equivalence. The model is able to reproduce linear primary creep as well as secondary and tertiary creep stages under high compressive stresses. For concrete in tension a simple viscoelastic formulation is applied. The material law is then incorporated into a finite element solution procedure for analysis of reinforced concrete structures. Numerical examples of uniaxial creep tests and concrete members show excellent agreement with experimental results.

• BMB Reports
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• 제44권5호
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• pp.312-316
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• 2011

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its toxic metabolite 1-methyl-4-phenylpyridium ion (MPP$^+$) have been shown to induce Parkinson's disease-like symptoms as well as neurotoxicity in humans and animal species. Recently, we reported that maintenance of redox balance and cellular defense against oxidative damage are primary functions of the novel antioxidant enzyme cytosolic NADP$^+$-dependent isocitrate dehydrogenase (IDPc). In this study, we examined the role of IDPc in cellular defense against MPP$^+$-induced oxidative injury using PC12 cells transfected with IDPc small interfering RNA (siRNA). Our results demonstrate that MPP$^+$-mediated disruption of cellular redox status, oxidative damage to cells, and apoptotic cell death were significantly enhanced by knockdown of IDPc.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2001년도 International Symposium on Dietary and Medicinal Antimutgens and Anticarcinogens
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• pp.50-51
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• 2001

DNA damage is an essential step in the pathogenesis of cancer and probably of other chronic degenerative conditions related to cigarette smoke (CS), such as atherosclerosis, cardiomyopathies, etc. Although the major goal of primary prevention is to refrain from smoking, chemoprevention by means of dietary and pharmacological agents provides a complementary preventive strategy. In spite of its overwhelming epidemiological importance, experimental studies evaluating CS as a complex mixture are relatively scanty.(omitted)

• 한국독성학회:학술대회논문집
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• 한국독성학회 2001년도 International Symposium on Effects of Edible Phytochemicals and Their Synthetic Derivatives on Carcinogenesis and Mutagenesis
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• pp.7-8
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• 2001

DNA damage is an essential step in the pathogenesis of cancer and probably of other chronic degenerative conditions related to cigarette smoke (CS), such as atherosclerosis, cardiomyopathies, etc. Although the major goal of primary prevention is to refrain from smoking, chemoprevention by means of dietary and pharmacological agents provides a complementary preventive strategy. In spite of its overwhelming epidemiological importance, experimental studies evaluating CS as a complex mixture are relatively scanty.(omitted)

• 대한수의학회지
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• 제39권2호
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• pp.370-375
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• 1999

Owner's attitudes for tendonectomy, the advantages of this surgical technique, and postoperative complication were investigated by telephone survey. 18 cats on whom tendoncetomy was performed with or without concurrent ovario-hysterectomy or castration were included in this study. The first reason for tendonectomy was to avoid damage caused by the cat's scratching household materials. The first benefit of tendonectomy was decreasing damage to materials (89%). The primary concern of the owners of cats that underwent tendonectomy was postoperative pain after surgery (61%). Twelve cats (67%) that underwent tendonectomy recovered fully within the first three days and 6 cats (33%) recovered within two weeks. After combining the very positive rating and positive as positive, seventeen owners (94%) of cats that underwent tendonectomy had a positive attitude to the surgery.

• Nuclear Engineering and Technology
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• 제36권3호
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• pp.229-236
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• 2004

Radiation hardening is a multiscale phenomenon involving various processes over a wide range of time and length. We present a multiscale model for estimating the amount of radiation hardening in pressure vessel steel in the environment of a light water reactor. The model comprises two main parts: molecular dynamics (MD) simulation and a point defect cluster (PDC) model. The MD simulation was used to investigate the primary damage caused by displacement cascades. The PDC model mathematically formulates interactions between point defects and their clusters, which explains the evolution of microstructures. We then used a dislocation barrier model to calculate the hardening due to the PDCs. The key input for this multiscale model is a neutron spectrum at the inner surface of reactor pressure vessel steel of the Younggwang Nuclear Power Plant No.5. A combined calculation from the MD simulation and the PDC model provides a convenient tool for estimating the amount of radiation hardening.

• Nuclear Engineering and Technology
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• 제46권4호
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• pp.475-480
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• 2014

We developed a simple method to prepare the displacement damage cross section of SiC using NJOY and SRIM/TRIM. The number of displacements per atom (DPA) dependent on primary knock-on atom (PKA) energy was computed using SRIM/TRIM and it is directly used by NJOY/HEATR to compute the neutron energy dependent DPA cross sections which are required to estimate the accumulated DPA of nuclear material. SiC DPA cross section is published as a table in DeCART 47 energy group structure. Proposed methodology can be easily extended to other materials.

• 대한기계학회논문집
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• 제18권11호
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• pp.2805-2816
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• 1994

This paper describes dynamic finite element analyses performed to study the dynamic behaviors of a shipping container under the impact onto rigid target due to the accidental fall from the hight of 9 m. Using two and three dimensional techniques, the shipping container which gave the maximum damage, ten different drop orientations are considered ; at intervals of $5^{\circ}$ from $45^{\circ}$ to $90^{\circ}$ According to the present results, the orientation of the shipping container which gave the maximum damage is $85^{\circ}$ from horizontal for oblique drop in the primary impact. In the optimal design of the shipping container, the impact limiter material must be considered importantly because it's proper selection affects the weight and the manufacturing cost of the shipping container. The analysis of the shipping container in this paper demonstrated that the shipping container is structurally sound relative to the regulatory drop test requirements.

• 대한소아치과학회지
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• 제29권3호
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• pp.444-449
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• 2002

치아의 맹출은 치아가 구강내 교합평면에 도달하여 기능적인 위치를 차지할 때까지의 치아 이동 및 골조직 내에서의 발달로 이루어지는 생리학적인 양상으로 이해되어진다. 그러나 치아가 정상적으로 맹출해야 하는 시기를 지나서도 골조직 내에서 맹출하지 않을 수 있으며, 이러한 치아를 매복치라 일컫는다. 이러한 치아 매복의 주된 요인은 국소적인 것으로 악궁내 공간 부족, 치아 위치 이상, 과잉치, 맹출 경로의 감염, 낭종 및 안면 외상으로 인한 치배의 영향 등이 있다. 또한 쇄골두개이골증, 골다공증 등의 전신적 그리고 유전적 질환도 맹출 장애와 맹출 지연 등과 관련이 있다. 현재까지 매복치의 대부분은 영구치로 보고되었으며 반면에 유치의 매복에 대한 것은 극히 소수에 불과하고, 매복된 유치의 대다수는 제 2 유구치이다. 유치의 매복은 유착에 의해 이차적으로 생긴 저위교합과는 구별되어야 하며, 유치의 매복에 대한 병인은 유치 치배의 비정상적인 발달로 인해 조기에 유착이 일어나는 것으로 추측되어지고 있으나, 아직까지 정확하게 밝혀진 바는 없다. 유치의 맹출 실패로 나타날 수 있는 문제점으로는 계승 영구치 발달 및 맹출 방해, 낭종 형성이나 감염의 발생 등을 생각해 볼 수 있다. 본 증례들은 연세대학교 치과대학병원 소아치과에 내원한 환아의 구강 및 방사선학적 검사에서 유구치의 매복이 관찰되었기에 이에 보고하는 바이다.

• 한국유체기계학회 논문집
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• 제2권3호
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• pp.24-29
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• 1999

The ASME strainers have been newly installed at the suction side of each reactor coolant pump to get rid of the foreign materials which may damage the pump impeller or interfere with the coolant path of fuel flow tube or primary plate type heat exchanger. The strainer was designed in accordance with ASME SEC. III, DIV. 1, Class 3 and the structural integrity was verified by seismic analysis. The screen was designed in accordance with the effective void area from the result of flow analysis for T-type strainer. After installation of the strainer, it was confirmed through the field test that the flow characteristics of primary cooling system were not adversely affected. The pressure loss coefficient was calculated by Darcy equation using the pressure difference through each strainer and the flow rate measured during the strainer performance test. And these are useful data to predict flow variations by the pressure difference.