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전기화학적 및 고압 수소 분위기하 템퍼드 마르텐사이트강의 수소취화 특성 비교
Sang-Gyu Kim,Jae-Yun Kim,Hyun-Joo Seo,Hwan-Gyo Jung,Jaeyoung Park,Un-Bong Baek,황병철 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.11
The effect of hydrogen charging methods on the hydrogen embrittlement characteristics of tempered martensitic steels were discussed in terms of hydrogen diffusion behavior. Two tempered martensitic steels with different Si content were fabricated by quenching and tempering. The steel with high Si content had a lower cementite fraction because the addition of Si changed the morphology of cementite from a long film-like shape to a short-rod shape by suppressing the precipitation and growth of the cementite. To evaluate the hydrogen embrittlement resistance of the two tempered martensitic steels with different Si content, slow strain-rate tensile testing was employed after introducing hydrogen using three types of hydrogen charging methods (ex-situ electrochemical hydrogen charging, in-situ electrochemical hydrogen charging, and in-situ high-pressure gaseous hydrogen environment). For the hydrogen pre-charged tensile specimens using the ex-situ electrochemical charging method, the steel with high Si content had a better hydrogen embrittlement resistance, with a higher relative reduction in area. On the other hand, there was no significant difference in the relative notch tensile strength of the two tempered martensitic steels with different Si content, regardless of the hydrogen charging methods. In addition, the ex-situ hydrogen charging method exhibited higher relative notch tensile strength compared to the in-situ hydrogen charging method due to the release of hydrogen during the tensile test, after exsitu hydrogen charging. This implies that hydrogen embrittlement resistance can be differently estimated depending on the kind of hydrogen charging methods.
Yun Sang Oh,Lee Kyo Won,Park Jae Berm,Min Jung Kim,박성윤,Park Boram 대한초음파의학회 2023 ULTRASONOGRAPHY Vol.42 No.2
Purpose: This study evaluated the role of donor kidney ultrasonography (US) for predicting functional kidney volume and identifying ideal kidney grafts in deceased donor kidney transplantation. Methods: In total, 272 patients who underwent deceased donor kidney transplantation from 2000 to 2020 at Samsung Medical Center were enrolled. Donor kidney information (i.e., right or left) was provided to the radiologist who performed US image re-analysis. To binarize each kidney’s ultrasound parameters, an optimal cutoff value for estimated glomerular filtration rate (eGFR) of less than 30 mL/min/1.73 m2 within 1 year after kidney transplantation was selected using the receiver operating characteristic curve with a specificity >60%. Cox regression analysis was performed for an eGFR less than 30 mL/min/1.73 m2 within 1 year after kidney transplantation and graft failure within 2 years after kidney transplantation. Results: The product of renal length and cortical thickness was a statistically significant predictor of graft function. The odds ratios of an eGFR less than 30 mL/min/1.73 m2 within a year after kidney transplantation and the hazard ratio of graft failure within 2 years after kidney transplantation were 5.91 (P=0.003) and 5.76 (P=0.022), respectively. Conclusion: Preoperative US of the donor kidney can be used to evaluate donor kidney function and can predict short-term graft survival. An imaging modality such as US should be included in the donor selection criteria as an additional recommendation. However, the purpose of this study was not to narrow the expanded criteria but to avoid catastrophic consequences by identifying ideal donor kidneys using preoperative US.
The Significance of Sedation Control in Patients Receiving Mechanical Ventilation
( Yun Jung Jung ),( Wou Young Chung ),( Miyeon Lee ),( Keu Sung Lee ),( Joo Hun Park ),( Seung Soo Sheen ),( Sung Chul Hwang ),( Kwang Joo Park ) 대한결핵 및 호흡기학회 2012 Tuberculosis and Respiratory Diseases Vol.73 No.3
Background: Adequate assessment and control of sedation play crucial roles in the proper performance of mechanical ventilation. Methods: A total of 30 patients with various pulmonary diseases were prospectively enrolled. The study population was randomized into two groups. The sedation assessment group (SAG) received active protocol-based control of sedation, and in the empiric control group (ECG), the sedation levels were empirically adjusted. Subsequently, daily interruption of sedation (DIS) was conducted in the SAG. Results: In the SAG, the dose of midazolam was significantly reduced by control of sedation (day 1, 1.3±0.5 μg/kg/min; day 2, 0.9±0.4μg/kg/min; p<0.01), and was significantly lower than the ECG on day 2 (p<0.01). Likewise, on day 2, sedation levels were significantly lower in the SAG than in the ECG. Significant relationship was found between Ramsay sedation scale and Richmond agitation-sedation scale (RASS; rs=-0.57), Ramsay Sedation Scale and Bispectral Index (BIS; rs=0.77), and RASS and BIS ( rs=-0.79). In 10 patients, who didn`t require re-sedation after DIS, BIS showed the earliest and most significant changes among the sedation scales. Ventilatory parameters showed significant but less prominent changes, and hemodynamic parameters didn`t show significant changes. No seriously adverse events ensued after the implementation of DIS. Conclusion: Active assessment and control of sedation significantly reduced the dosage of sedatives in patients receiving mechanical ventilation. DIS, conducted in limited cases, suggested its potential efficacy and tolerability.
Yun, Jung-Ho,Lee, Sang-Koo The Korean Neurosurgical Society 2014 Journal of Korean neurosurgical society Vol.56 No.6
Primary intraosseous meningioma is a rare tumor, and atypical pathologic components both osteolytic lesion and dura and soft tissue invasion is extremely rare. A 65-year-old woman presented with a 5-month history of a soft mass on the right frontal area. MR imaging revealed a 4 cm sized, multilobulated, strongly-enhancing lesion on the right frontal bone, and CT showed a destructive skull lesion. The mass was adhered tightly to the scalp and dura mater, and it extended to some part of the outer and inner dural layers without brain invasion. The extradural mass and soft tissue mass were totally removed simultaneously and we reconstructed the calvarial defect with artificial bone material. The pathological study revealed an atypical meningioma as World Health Organization grade II. Six months after the operation, brain MR imaging showed that not found recurrence in both cranial and spinal lesion. Here, we report a case of primary osteolytic intraosseous atypical meningioma with soft tissue and dural invasion.