• Journal of Chest Surgery
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• 제42권1호
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• pp.92-95
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• 2009

유육종증은 면역 반응에 의한 전신 육아종성 염증 질환으로 20~60%에서 심장을 침범하는 것으로 알려져 있으나 심장에만 국한된 유육종증(Isolated cardiac sarcoidosis)은 매우 드물며, 전신 증상의 발현이 없는 제한된 경우에 심장 이식을 고려해 볼 수 있다. 저자들은 완전 방실 차단으로 영구형 심장 박동 조율기(Permanent pacemaker)를 삽입한 심장 유육종증 환자에서 스테로이드에 반응하지 않는 심부전의 악화로 심장 이식을 시행하였기에 보고하는 바이다.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.208-219
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• 2000

In this study, static axial crush tests were performed with the new aluminum/GFRP hybrid tube. Glass/Epoxy prepregs were wrapped around an aluminum tube and co-cured. The failure of the hybrid tube was stable and progressive without trigger mechanism, and specific energy absorption was increased to the maximum of 33% in comparison with the aluminum tube. Effective energy absorption is possible for an inner aluminum tube because a wrapped composite tube constrains the deflection of an aluminum tube. The failure of a hybrid composite tube was stable without trigger mechanism because the inner aluminum tube could play the role of the crack initiator and controller. Mean crushing load could be calculated by modifying the plastic hinge collapse model for hybrid materials. The predicted results by this analytical model showed good agreement with the experimental results. It can be said that Aluminum/Glass-Epoxy hybrid tube is suitable for the vehicle front structure because this hybrid tube shows effective energy absorption, easy production, and simple application capability for RTM process.

• Geomechanics and Engineering
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• 제8권6호
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• pp.829-844
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• 2015

In the current paper the results of a numerical simulation that were verified by a well instrumented experimental procedure for studying the arching effect over a trapdoor in sand is presented. To simulate this phenomenon with continuum mechanics, the experimental procedure is modeled in ABAQUS code using stress dependent hardening in elastic state and plastic strain dependent frictional hardening-softening with Mohr Coulomb failure criterion applying user sub-routine. The apparatus comprises rectangular trapdoors with different width that can yield downward while stresses and deformations are recorded simultaneously. As the trapdoor starts to yield, the whole soil mass deforms elastically. However, after an immediate specified displacement, depending on the width of the trapdoor, the soil mass behaves plastically. This behavior of sand occurs due to the flow phenomenon and continues until the stress on trapdoor is minimized. Then the failure process develops in sand and the measured stress on the trapdoor shows an ascending trend. This indicates gradual separation of the yielding mass from the whole soil body. Finally, the flow process leads to establish a stable vault of sand called arching mechanism or progressive collapse of the soil body.

• Childhood Kidney Diseases
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• 제1권2호
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• pp.183-188
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• 1997

Familial juvenile hyperuricemic nephropathy is an autosomal dominant disease characterized by progressive renal disease and hyperuricemia or gout, affecting young people of either sex equally. There are two biochemical markers of this disorder. The first is hyperuricemia disproportionate to the degree of renal dysfunction; the second is a grossly reduced clearance of uric acid relative to creatinine, dispropotionate to age, sex and degree of renal failure. We experienced 2 family members with hyperuricemia. One family member, a 13-year-old girl who had suffered from tophaceous gout and chronic renal failure. Her younger brother also had hyperuricemia and moderately reduced renal function. Their urinary excretion fractions of uric acid($FE_{uric\;acid}$) were reduced and renal biopsy specimens showed interstitial fibrosis with tubular atrophy and interstitial urate crystal deposition. We have treated these two patients with allopurinol but we have done renal transplantation because she progressed to end stage renal disease at 16 year old age.

• 대한조선학회논문집
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• 제52권3호
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• pp.248-254
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• 2015

The strength and fatigue life of Satin and Twill-woven CF/epoxy composite(CFRP) have been investigated. Damage mechanism fatigue method has been used to assess fatigue damage accumulation. It is based on measured residual stiffness and residual strength of carbon-fiber reinforced plastic(CFRP) laminates under cyclic loading. Fatigue damage evolution in composite laminates and predict fatigue life of the laminates were simulated by finite element analysis(FEA) method. The stress analysis was carried out in MSC patran/Nastran. A modified Hashin's failure criterion di rmfjapplied to predict the failure of the experimental data of fatigue life but a Ye-delamination criterion was ignored because of 2D modeling. Almost linear stiffness and strength degradation were observed during most of the fatigue process. These stress distribution data were adopted in the simulation to simulate fatigue behavior and estimate life of the laminates. From the results, the predicted fatigue life is more conservatively estimated than the experimental results.

• 콘크리트학회논문집
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• 제17권6호
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• pp.1053-1064
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• 2005

The mechanical damage of concrete is normally attributed to the formation of microcracks and their propagation and coalescence into macroscopic cracks. This physical degradation is caused from progressive and hierarchical damage of the microstructure due to debonding and slip along bimaterial interfaces at the mesoscale. Their growth and coalescence leads to initiation of hairline discrete cracks at the mesoscale. Eventually, single or multiple major discrete cracks develop at the macroscale. In this paper, from this conceptual model of mechanical damage in concrete, the computational efforts were made in order to characterize physical cracks and how to quantify the damage of concrete materials within the laws of thermodynamics with the aid of interface element in traditional finite element methodology. One dimensional effective traction/jump constitutive interface law is introduced in order to accommodate the normal opening and tangential slips on the interfaces between different materials(adhesion) or similar materials(cohesion) in two and three dimensional problems. Mode I failure and mixed mode failure of various geometries and boundary conditions are discussed in the sense of crack propagation and their spent of fracture energy under monotonic displacement control.

• Journal of Preventive Medicine and Public Health
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• 제22권4호
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• pp.454-465
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• 1989

In a small island community with a population of less than 100 residents, nine persons died and five experienced severe illnesses during the period from November 1986 to May 1988. Their initial symptoms were sore throat and fever. Renal failure and hepatitis developed within one week after the onset. Oral mucosal ulcer developed in some cases. After one week, progressive respiratory failure and dyspnea developed evidently and severe respiratory distress and hypoxia preceded those fatal cases. Chest X-ray findings revealed bilateral diffuse multiple cystic lesion with occasional multiple large emphysematous bullae. Based on these features paraquat poisoning was diagnosed and route of poisoning was investigated. In three sources of drinking water, trace amount of paraquat was detected in November 1988, six months after the incidence of recent fatal case. In November 1988, soybean sauces and soybean pastes from 12 households were found contaminated with high concentration of paraquat, the cause could not be identified. The possibility of the contamination of drinking water as the cause of this mass poisoning has been suggested.

• 산업노동연구
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• 제23권1호
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• pp.165-195
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• 2017

본 논문은 부조리한 삶의 경계에 선 사람들을 인정투쟁의 관점에서 다룬다. 경계인은 1970년대부터 노동운동에 뛰어 든 사람들이다. 그리고 인정투쟁은 사랑, 권리, 가치부여의 측면에서 사회구성원으로부터 인정받기 위한 투쟁이다. 본 논문은 이들이 인정을 위한 열정으로부터 좌절된 과정을 분석한다. 경계인들은 인정을 위해 민주노조를 건설했고, 진보정당으로 결실을 맺었다. 그런데 부조리한 세상에 맞섰던 사람들은 개혁과 혁명의 경계인에서 무기력과 우울증이라는 갈림길에 있다. 열정이 식고 우울증의 현상이 심화되고 있는 이유는 무엇인가? 본 논문은 혁명을 꿈꾸면서 의인이었던 이들이 인정되지 못하고 여전히 밖에서 경계인이 되고 좌절과 무기력에 있는 핵심적인 이유로 내부와 외부와의 다양한 측면에서 균열을 지적했고 이를 극복하기 위해 균열을 극복하기 위한 소통을 대안으로 제시했다.

• Advances in materials Research
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• 제8권1호
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• pp.11-24
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• 2019

This paper presents a review study for energy-efficient gas turbines (GTs) with cycles which contributes significantly towards sustainable usage. Nonetheless, these progressive engines, operative at turbine inlet temperatures as high as $1600^{\circ}C$, require the employment of highly creep resistant materials for use in hotter section components of gas turbines like combustion chamber and blades. However, the gas turbine obtain its driving power by utilizing the energy of treated gases and air which is at piercing temperature and pushing by expanding through the several rings of steady and vibratory blades. Since the turbine blades works at very high temperature and pressure, high stress concentration are observed on the blades. With the increasing demand of service, to provide adequate efficiency and power within the optimized level, turbine blades are to be made of those materials which can withstand high thermal and working load condition for longer cycle time. This paper depicts the recent developments in the field of implementing the best suited materials for the GTs, selection of proper Thermal Barrier Coating (TBC), fracture analysis and experiments on failed or used turbine blades and several other designing and operating factors which are effecting the blade life and efficiency. It is revealed that Nickel based Superalloys were promising, Cast Iron with Zirconium and Pt-Al coatings are used as best TBC material, material defects are the foremost and prominent reason for blade failure.

• Tribology and Lubricants
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• 제37권5호
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• pp.179-188
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• 2021

Reputed for their low friction coefficient and wear protection effect, diamond-like carbon (DLC) materials are considered amongst the most important lubricant coatings for tribological applications. In this framework, this investigation aims to elucidate the effect of a few operating parameters, such as applied stress and sliding amplitude on the friction lifetime of DLC coatings. Fretting wear tests are conducted using a 12.7 mm radius counterpart of 52100 steel balls slid against a substrate of the same material coated with a 2 ㎛ thickness DLC. Approximately, 5 to 57 N force is applied, generating a maximum Hertzian contact pressure of 430 to 662 MPa, corresponding to the applied force. The coefficient of friction (CoF) generates three regimes, first a running-in period regime, followed by a steady-state evolution regime, and finally a progressive increase of the CoF reaching the steel CoF value, as an indicator of reaching the substrate. To track the wear scenario, interrupted tests are performed with analysis combining scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), 3D profilometer and micro-Raman spectroscopy. The results show two endurance values: one characterizing the coating failure (Nc₁), and the other (Nc₂) indicating the friction failure which is situated where the CoF reaches a threshold value of μ_th = 0.3 in the third regime. The Archard energy density factor is used to determine the two endurance values (Nc₁, Nc₂). Based on this approach, a master curve is established delimitating both the coating and the friction endurances.