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9-12%Cr강의 첨가원소 및 열처리에 따른 미세조직거동과 경도변화
주성욱,유정훈,신기삼,허성강,이재현,석진익,김병훈,김정태 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-
9-12%Cr steel are getting increasing attention for expanded application as high temperature materials applicable for gas turbine compressors, steam turbine rotors, blade and casing. For efficient and extensive application of 9-12%Cr steel, the data in addition to the improvement of mechanical properties on the correlation of microstructural evolution and mechanical properties are inevitable and thus the investigation in this study is performed for the determination for the specimens heat-treated at 600, 650 and 700℃ for 1000, 3000 and 5000hrs. The microstructure of as-received specimen was tempered martensite, with a high dislocation density and secondary phases. Upon high temperature heat-treatment, the martensite lath got larger and dislocation density decreased resulting the reduction of the strength. In addition, sharp growth of secondary phases was observed in the specimen heat-treated at 700℃ for 5000hrs. A specimen aged at 600℃ and 650℃ Laves phase was observed. The hardness showed close relationship with the secondary phase particle and dislocation density.
탄소섬유그리드를 이용한 RC보의 보강효과에 관한 실험적 연구
이인희,심낙훈,김정재,박영석 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-
Reinforced concrete structures are damaged by material, environmental, and physical factors during service period. Also, when we designed, the stiffness of member should be increased because of unexpected overloads and decreased durability. So, recently, repair and strengthening are became a concern on reinforced concrete structure. On this study, damaged reinforced concrete member are reinforced using carbon fiber grid, new multi cumulated material. And effect of reinforcement is experimentally analyzed. First of all, material properties of carbon fiber grid, uncontracted polymer mortar, and rapidly hardening mortar are experimentally researched. And then, application is verified by shear test and attachment test with two kinds test specimen, respectively. Using five actual size RC beam (width 40cm, height 50cm, length 650cm), yield strength test and bending test are carried out. Finally, yielded five specimens are reinforced with each other methods and fracture strength test is carried out. That results are compared and analyzed to confirm the reinforcement effect.
Je Hoon Jeong,Min-Woo Jo,Dong-Kyu Chin,Woo-Seung Son,Minsu Ock,Jung-Kil Lee 대한신경손상학회 2022 Korean Journal of Neurotrauma Vol.18 No.2
This erratum is being published to correct the error on page 64 of the article entitled “Validation of the European Quality of Life-5 Dimensions, 3-Level Version (EQ-5D-3L) in Patients With Osteoporotic Vertebral Fracture and Comparing Their Health-Related Quality of Life with That of the General Population in Korea” (Korean J Neurotrauma 2022;18(1):64-74).
Electron Microscopic Study in the Rat Model of Electrically Injured Myelopathy: Preliminary Report
Je Hoon Jeong,Cheong Hoon Seo,Dae Hoon Lee 대한신경손상학회 2023 Korean Journal of Neurotrauma Vol.19 No.2
The patient with electrically injured myelopathy showed mild motor weakness without somatosensory pathway abnormalities. Few reports have been reported on the pathophysiological mechanisms of electrically injured myelopathy, and there is controversy about the exact pathological causes. This study aimed to investigate the ultrastructural changes in the electron microscopic findings of electrical spinal cord injury.
The Effect of Biocomposite Screws on Bone Regeneration in a Rat Osteoporosis Model
Jeong, Je Hoon,Jin, Eun-Sun,Kim, Ji Yeon,Lee, Bora,Min, JoongKee,Jeon, Sang Ryong,Lee, Minsu,Choi, Kyoung Hyo Elsevier 2017 World neurosurgery Vol.106 No.-
<P><B>Objective</B></P> <P>To evaluate the efficacy of biocomposite screws used in ovariectomy (OVX)-induced osteoporotic rats.</P> <P><B>Methods</B></P> <P>Twenty-four female Wistar rats (250–300 g, 12 weeks old) were divided into 4 groups: sham group (control), OVX-induced osteoporosis group (OVX), OVX and biodegradable poly(lactic-<I>co</I>-glycolic acid) (PLGA) without tricalcium phosphate (β-TCP) screw insertion group (OVX/BSR), and OVX and biocomposite (PLGA with β-TCP) screw insertion group (OVX/CSR). Three groups underwent bilateral OVX, and of these, 2 groups had 2 different types of screw inserted at the proximal tibia. At 25 weeks after OVX, the bilateral tibias were extracted. The extracted tibiae were scanned by ex vivo micro-computed tomography (CT) and stained with hematoxylin and eosin (H&E) and with Masson's trichrome stain for pathological assessment.</P> <P><B>Results</B></P> <P>Compared with the ovariectomized groups, the control group had the highest values for bone mineral density (BMD), bone volume (BV)/total volume (TV), and trabecular number (Tb.N) and the lowest values for trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp). In the pairwise comparison among ovariectomized groups, the OVX/CSR group had significantly higher BMD, BV/TV, and Tb.N values than the other 2 groups (OVX and OVX/BSR) and significantly lower Tb.Sp. Micro-CT scans showed clear evidence of new trabecular formation near the screw insertion site in the OVX/CSR group only. Analyses of H&E- and Masson's trichrome–stained sections showed more and thicker trabecular bone around the implant in the OVX/CSR group compared with the OVX and OVX/BSR groups.</P> <P><B>Conclusions</B></P> <P>Biocomposite screws can improve local bone quality and facilitate osteoconductivity in an osteoporotic rat model.</P>
Je Hoon Jeong,Jun Seok Koh,Eui Jong Kim 대한영상의학회 2007 Korean Journal of Radiology Vol.8 No.1
Objective: The presence of an intracerebral hematoma from a ruptured aneurysm is a negative predictive factor and it is associated with high morbidity and mortality rates even though clot evacuation followed by the neck clipping is performed. Endovascular coil embolization is a useful alternative procedure to reduce the surgical morbidity and mortality rates. We report here on our experiences with the alternative option of endovascular coil placement followed by craniotomy for clot evacuation. Materials and Methods: Among 312 patients who were admitted with intracerebral subarachnoid hemorrhage during the recent three years, 119 cases were treated via the endovascular approach. Nine cases were suspected to show aneurysmal intracerebral hemorrhage (ICH) on CT scan and they underwent emergency cerebral angiograms. We performed immediate coil embolization at the same session of angiographic examination, and this was followed by clot evacuation. Results: Seven cases showed to have ruptured middle cerebral artery (MCA) aneurysms and two cases had internal carotid artery aneurysms. The clinical status on admission was Hunt-Hess grade (HHG) IV in seven patients and HHG III two. Surgical evacuation of the clot was done immediately after the endovascular coil placement. The treatment results were a Glasgow Outcome Scale score good recovery and moderate disability in six patients (66.7%). No mortality was recorded and no procedural morbidity was incurred by both the endovascular and direct craniotomy procedures. Conclusion: The results indicate that the coil embolization followed by clot evacuation for the patients with aneurysmal ICH may be a less invasive and quite valuable alternative treatment for this patient group, and this warrants further investigation.
Carotid sparing intensity modulated radiotherapy on early glottic cancer: preliminary study
Choi, Hoon Sik,Jeong, Bae Kwon,Jeong, Hojin,Song, Jin Ho,Kim, Jin Pyeong,Park, Jung Je,Woo, Seung Hoon,Kang, Ki Mun The Korean Society for Radiation Oncology 2016 Radiation Oncology Journal Vol.34 No.1
Purpose: To compare the dose distribution between carotid sparing intensity modulated radiotherapy (IMRT) and opposed lateral field technique (LAFT), and to determine the effects of carotid sparing IMRT in early glottic cancer patients who have risk factors for atherosclerosis. Materials and Methods: Ten early glottic cancer patients were treated with carotid sparing IMRT. For each patient, the conventional LAFT plan was developed for comparison. IMRT and LAFT plans were compared in terms of planning target volume (PTV) coverage, conformity index, homogeneity index, and the doses to planning organ at risk volume (PRV) for carotid arteries, spinal cord and pharyngeal constrictor muscle. Results: Recurrence was not observed in any patients during the follow-up period. $V_{95%}$ for PTV showed no significant difference between IMRT and LAFT plans, while $V_{100%}$ was significantly higher in the IMRT plan (95.5% vs. 94.6%, p = 0.005). The homogeneity index (11.6%) and conformity index (1.4) in the IMRT plan were significantly better than those in the LAFT plans (8.5% and 5.1, respectively) (p = 0.005). The median $V_{5Gy}$ (90.0%), $V_{25Gy}$ (13.5%), and $V_{50Gy}$ (0%) for carotid artery PRV in the IMRT plan were significantly lower than those in the LAFT plan (99.1%, 89.0%, and 77.3%, respectively) (p = 0.005). Conclusion: Our study suggests that carotid sparing IMRT can significantly decrease the dose to carotid arteries compared to LAFT, and it would be considered for early glottic cancer patient with high risk of atherosclerosis.