• 한국수소및신에너지학회논문집
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• 제34권1호
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• pp.26-31
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• 2023

In this study, in order to propose a modular method for type IV high aspect ratio modular hydrogen storage vessel, a numerical analysis was conducted on the heat transfer behavior in series and parallel connection methods, and the differences according to each connection method were reviewed. Computational fluid dynamics software was used to check the internal temperature and pressure values of the hydrogen storage container under charging conditions. In terms of thermal safety when charging hydrogen gas, it was confirmed that the parallel modularization method was superior.

• 한국수소및신에너지학회논문집
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• 제34권1호
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• pp.32-37
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• 2023

In this study, in order to propose a integrity evaluation for type IV high aspect ratio hydrogen storage vessel, a numerical analysis of the hoop tensile test and pressure test was performed using FEM software, and the results of the actual physical property test were reviewed. The property test and numerical analysis were compared, and very similar results were obtained with deviations of maximum tensile strength of 4.75% and fiber direction stress of 5.39%.

• Composites Research
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• 제29권2호
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• pp.60-65
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• 2016

본 연구에서는 Type IV 수소 압력용기 시제품의 충격하중 조건에 따른 구조 건전성을 분석하고자 유한요소해석과 FBG 센서 삽입을 통한 실시간 모니터링 실험을 수행하여 결과를 분석하였다. 플라이 모델링 기법을 활용한 유한요소해석을 통해 FBG 센서를 삽입할 수소 압력용기의 취약부 선정 및 가압 조건을 제시하였으며, 실험을 진행할 기초 정보를 확보하였다. 실제 용기제작에 앞서 시편 실험을 통해 FBG 센서의 삽입방식 신뢰성을 확보하였으며, 이후 해당 결과를 활용하여 필라멘트 와인딩 공정에 적용하였다. 비충격 가압 피로실험과 총 4회의 충격 피로실험을 수행하였다. 실험결과 비충격 가압 피로실험에서는 해석과 동일한 거동을 보였으며, 4회의 충격 피로실험에서는 용기의 충전 시간이 점진적으로 증가하고 충전률은 감소하는 것을 확인하였다.

• 소성∙가공
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• 제28권4호
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• pp.203-211
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• 2019

In this study, the weight of type IV pressure vessel is optimized through the burst pressure condition using the finite element analysis (FEA) based on the genetic algorithm (GA). The optimization design variables include the thickness of composite layers and the winding angles. The optimized design variables are validated using the numerical simulations for the pressure vessel. Consequently, the weight is decreased by about 6.5% as compared to the previously reported results for Type III pressure vessel. Additionally, a method which reduces the entire optimization time is proposed. In the original method, the population size is constant across all generations. However, the proposed method could reduce the workload through the reduction of the population size by half for every 25 generations. Thus, the proposed method is observed to increase the weight by about 0.1%, however, the working time for the optimization could be decreased by about 46.5%.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.644-647
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• 2009

In this paper, the study is researched for related safety standards having experiments concerning temperature changes in type IV cylinder of the Hydrogen fuel cell vehicle. Experiments were performed to acquire temperature data of type IV cylinder according to filling time. The experimental results are shown that internal temperatures of type Ⅳ vessel are over $85^{\circ}C$ at all measured points after 5 minutes at filling 35 MPa and the highest temperature is getting lower when the residual gases are more remained. Consequently, the safety standards need properly limited value through further study for filling flow rate and filling time.

• Journal of Korean Neurosurgical Society
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• 제29권12호
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• pp.1584-1591
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• 2000

Objective : Until now, it has been little known about the biological mechanisms associated with the genesis, growth, and rupture of intracranial aneurysm. This study was performed to investigate and understand a part of these mechanisms. Materials and Methods : Immunohistochemical stains for angiogenesis growth factors(basic fibroblast growth factor (bFGF) and vascular endothelial growth factor(VEGF)) and selected vascular wall matrix proteins(alpha smooth muscle actin(${\alpha}SMA$) and collagen Type IV) were performed in fixed sections from a normal circle of Willis artery which was taken from the autopsy specimen as a control vessel and 17 aneurysmal wall specimens which was taken during surgical clipping of aneurysms. The staining intensity and distribution of immunoreactivity to angiogenesis growth factors and selected wall matrix proteins in control vessel and aneurysmal wall were examined and compared with each other. The difference of staining intensity according to the size of aneurysm was also investigated. Results : There was no immunoreactivity to bFGF and VEGF in the control vessel. bFGF immunoreactivity was exhibited in 15 of 17 aneurysm specimens around smooth muscle cells within the media of aneurysm. VEGF immunoreactivity was also exhibited in all aneurysm specimens in patches or diffusely affecting all layers of the aneurysmal wall. The degrees of intensity of bFGF and VEGF immunoexpression were proportionate roughly to the size of aneurysm. Strong immunoexpression of both factors were noticed in large aneurysm. A regularly arranged and defined band of immunoreactivity of ${\alpha}SMA$ was noticed in the media of the control vessel, whereas diffuse, faint, irregularly arranged ${\alpha}SMA$ was noticed in the aneurysmal wall. A regularly defined band of collagen Type IV immunoreactivity was also noticed in the subendothelium of the control vessel, whereas diffuse disorganized immunoreactivity of collagen Type IV was noticed in the entire wall of the aneurysm. Conclusion : These results indicate substantial evidences of abnormal expression of angiogenesis factors and changes of selected vascular wall matrix proteins in the wall of intracranial aneurysm. The unbalanced changes of angiogenesis factors and vascular wall matrix proteins in the wall of aneurysm may be one of the biological mechanisms for the growth and rupture of aneurysm.

• 항공우주시스템공학회지
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• 제17권6호
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• pp.127-132
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• 2023

본 연구에서는 필라멘트 와인딩 공법을 적용한 Type 4 압력용기의 설계를 수행하였다. 수소저장용 탱크의 설계인 점을 고려하여 누설을 방지하기 위해 라이너는 고분자 고밀도 폴리에틸렌(HDPE)을 적용하였고 복합재 구조는 카본/에폭시를 Hoop 방향과 Helical 방향으로 적층하여 설계하였다. 이론적 접근으로 Helical 섬유의 각도와 Hoop, Helical 각각의 섬유 두께를 결정하여 설계하였다. 설계에 대한 안전성은 상용소프트웨어인 ANSYS를 활용하여 유한요소 해석으로 검증하였다.

• Nuclear Engineering and Technology
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• 제39권4호
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• pp.257-272
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• 2007

Supercritical water-cooled reactors (SCWRs) are recognized as a Generation IV reactor concept. The Super LWR is a pressure-vessel type thermal spectrum SCWR with downward-flow water rods and is currently under study at the University of Tokyo. This paper reviews Super LWR safety. The fundamental requirement for the Super LWR, which has a once-through coolant cycle, is the core coolant flow rate rather than the coolant inventory. Key safety characteristics of the Super LWR inhere in the design features and have been identified through a series of safety analyses. Although loss-of-flow is the most important abnormality, fuel rod heat-up is mitigated by the "heat sink" and "water source" effects of the water rods. Response of the reactor power against pressurization events is mild due to a small change in the average coolant density and flow stagnation of the once-through coolant cycle. These mild responses against transients and also reactivity feedbacks provide good inherent safety against anticipated-transient-without-scram (ATWS) events without alternative actions. Initiation of an automatic depressurization system provides effective heat removal from the fuel rods. An "in-vessel accumulator" effect of the reactor vessel top dome enhances the fuel rod cooling. This effect enlarges the safety margin for large LOCA.

• Journal of Chest Surgery
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• 제13권3호
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• pp.243-249
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• 1980

Truncus ateriosus is one of the cyanotic congenital heart disease. The incidence is relatively uncommon, as 0.4% of totoal congenital heart disease. Embryologically the defect is due to a lack of partitioning of the embryonic truncus and conus during the first few weeks of fetal life. The ventricular septal defect is invariable present. A single arterial vessel arises from the heart and supplies blood to the aorta, the lung, and the coronary arteries. In 1949, collett and Edwards classified this defect according to anatomic variation to four major types, such as type I, II, III, and IV. Type IV is defined that pulmonary arteries are absent, and the pulmonary arterial supply arises from the descending thoracic aorta. This patients often have a continuous murmur head particularly well in the interscapular area. No effective surgical treatment is available. We have experienced one case of truncus arteriosus, type IV of Collett and Edwards in the Department of Thoracic and Cardiovascular Surgery, Kyungbook National University Hospital. This patient was 10 year-old girl. The chief complaints were cyanosis and dyspnea on exertion since birth. She was admitted at this hospital on April 16, 1980. The continous machinery murmur was heard loudest at the interscapular area. The chest X-ray films revealed cardiomegaly with an increase in pulmonaryvascular markings. The pulmonary secotr was significantly concave. No filling of pulmonary arteries noticed by the right ventriculogram. There was possible biventricular hypertrophy in EKG. The echocardiogram showed that the demension of the aortic root was larger than normal and minimal increase of the left ventricular internal dimension. The cardiac catheterization data was obtained by use of the great saphenus vein approach. The systolic pressure of the right ventricular outflow tract was 80 mmHg and was similar to that of the aorta. The oxygen saturation data revealed the evidence of the left to right shunt at the level of ventricular septum. The patient was operated and the diagnosis was confirmed as trucus arteriosus, type IV. No effective surgical interventins were performed.

• Journal of Korean Neurosurgical Society
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• 제63권4호
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• pp.427-432
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• 2020

Three randomized control trials (RCTs), published in 2013, investigated efficacy of mechanical thrombectomy in large vessel occlusions and did not show better results compared to intravenous (IV) recombinant tissue-type plasminogen activator (tPA) alone. However, most clinicians treating stroke consider mechanical thrombectomy as the standard treatment rather than using IV tPA alone. This paradigm shift was based on five RCTs investigating efficacy of mechanical thrombectomy in acute ischemic stroke conducted from 2010 to 2015. They demonstrated that mechanical thrombectomy was effective and safe in acute ischemic stroke with anterior circulation occlusion when performed within 6 hours of stroke onset. There are four reasons underlying the different results observed between the trials conducted in 2013 and 2015. First, the three RCTs of 2013 used low-efficiency thrombectomy devices. Second, the three RCTs used insufficient image selection criteria. Third, following the initial presentation at the hospital, reperfusion treatment required a long time. Fourth, the three RCTs showed a low rate of successful recanalization. Time is the most important factor in the treatment of acute ischemic stroke. However, current trends utilize advanced imaging techniques, such as diffusion-weighted imaging and multi-channel computer tomographic perfusion, to facilitate the detection of core infarction, penumbra, and collateral flows. These efforts demonstrate that patient selection may overcome the barriers of time in specific cases.