The removal of zinc from contaminated dredged-sediments

Dredged-sediments increased to about 15million m2 from 1998 to 2012 by port construction, sediment reclamation and dredging business. Most of dredged-sediments which are generated in Korea have been treated by Marine dumping. However, there are increasing concern about contamination by heavy metals in dredged-sediments. Therefore, it is required to remove heavy metals from dredged-sediments. The purpose of this study is to remove zinc from domestic dredged sediments contaminated with ZnS using ferric chloride. Consequently, leaching behavior of zinc was investigated under the following leaching conditions400rpm, 80℃ and 0.5M FeCl3 in 1M HCl, and content of zinc in residue decreased to 184mg/kg which meet Marine dumping regulations(Zn:200mg/kg). The shrinking core model(Ash diffusion controlled) was investigated based on the leaching results. Correlation coefficients were closed to 1 so that model best fitted to the kinetic data. The activation energy for the leaching process was found to be 64.1-76.9kJ/mol for 1-0.25M FeCl3 respectively, and that means leaching precess depends on chemical reaction.40 and 90℃ in temperature, 0.25-1M in concentration of ferric ion, 5-20% in pulp density, and 200-600rpm in stirring speed. Leaching efficiency of zinc increased with leaching temperature and ferric ion concentration. The leaching efficiency was 96.7% under the following conditions제 1 장. 서 론 1 1.1 개요 1 1.2 연구사례 7 1.2.1 3가 철 이온의 특징 7 1.2.2 침출연구사례 7 제 2 장. 이론적 배경 11 2.1 열역학적 해석 11 2.2 속도론적 해석 13 제 3 장. 침출거동 확인 19 3.1 사용시료 19 3.2 실험방법 19 3.3 실험결과 22 3.3.1 교반속도에 따른 침출거동 22 3.3.2 Fe3+ 농도에 따른 침출거동 24 3.3.3 광액비 변화에 따른 침출거동 25 3.3.4 온도변화에 따른 침출거동 27 제 4 장. 속도론적 해석결과 31 4.1 Shrinking core model (Film diffusion controlled) 31 4.2 Shrinking core model (Reaction controlled) 35 4.3 Shrinking core model (Ash diffusion controlled) 39 4.4 Dickinson and Heal model 42 4.5 활성화 에너지(Activation energy) 47 제 5 장. 결론 50 참고문헌 52 감사의 글 5

Comparison Between 3-Dimensional-Printed Titanium and Polyetheretherketone Cages: 1-Year Outcome After Minimally Invasive Transforaminal Interbody Fusion

Objective: Three-dimensional (3D)-printed titanium implants have been developed recently, but the utility is not yet proven. The aim of this study was to compare 3D-printed titanium and polyetheretherketone (PEEK) implants after minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Methods: Between October 2018 and September 2021, we retrospectively analyzed 83 patients who underwent single-level MIS-TLIF (3D-printed titanium, 40; PEEK, 43). Radiologic parameters were assessed with x-ray and computed tomography (CT) at postoperative 1 week, 6 months, and 1 year. Clinical status was evaluated using Oswestry Disability Index, visual analogue scale score, and Bridwell fusion grading was assessed on 6-month and 1-year postoperative CT. Results: There were no differences between the 2 groups in demographics and clinical outcomes. At 1-year of follow-up, the reported 3D-printed titanium fusion grades were grade I: 77.5% (31 patients), grade II: 17.5% (7 patients), and grade III: 5% (2 patients). The PEEK fusion grades were grade I: 51.2% (22 patients), grade II: 41.9% (18 patients), and grade III: 7.0% (3 patients). For overall fusion rate (grade I + II), there was no difference between the 2 cages (95.0% vs. 93.0%, p = 0.705), but grade I was reported at a higher incidence in 3D-printed titanium than PEEK (77.5% vs. 51.2%, p = 0.013). There was no difference between cages based on subsidence and complications. Conclusion: There were no significant differences in the overall fusion rate for MIS-TLIF surgery between 3D-printed titanium and PEEK, but the fusion grade was better in 3D-printed titanium than in PEEK. Long-term follow-up is required to verify the effectiveness.ope

Outcomes of Stent-Assisted Coiling Using the Neuroform Atlas Stent in Unruptured Wide-Necked Intracranial Aneurysms

Objective: Although stent-assisted coiling (SAC) has been reported to be safe and effective in treating wide-necked aneurysms, the technique has procedure-related complications. Thus, we reported our experiences of SAC using the Neuroform Atlas stent in treating wide-necked aneurysms and evaluated the incidence of and risk factors for procedure-related complications. Methods: From March 2018 to August 2019, we treated 130 unruptured wide-necked aneurysms in 123 patients with Neuroform Atlas stents. Angiographic results and clinical outcomes were reviewed retrospectively. Clinical and angiographic follow-up were performed in all cases (mean, 12.4 months) after the procedure. Results: There were eight cases (6.2%) of procedure-related complications (two dissections, five thromboembolisms, and one hemorrhage) and two (1.5%) of delayed complications (one ischemia and one hemorrhage). There was one case (0.8%) of failure of stent deployment and one (0.8%) of suboptimal positioning of the stent. Follow-up angiography showed complete obliteration in 103 (79.2%), residual neck in 16 (12.3%), and residual aneurysm in 11 cases (8.5%). Aneurysm locations in the middle cerebral artery (odds ratio [OR], 2.211; p=0.046) and the anterior communicating artery (OR, 2.850; p=0.039) were associated with procedurerelated complications on univariate analysis. However, no independent risk factor for procedure-related complications was noted in multivariate analysis. Conclusion: The Neuroform Atlas showed a high rate of technical success. Good clinical and radiographic outcomes in early follow-up suggests that the device is feasible and safe. SAC of aneurysms on the middle cerebral artery or anterior communicating artery may require more attention to prevent possible procedure-related complications.ope

Spatial location of R&D

학위논문(박사)--서울大學校 環境大學院 :環境計劃學科,1995.Docto

Impact Damage of Carbon/ Epoxy Composite Materials Subjected to Impact Loading

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Comparison of Unilateral Biportal Endoscopic Discectomy with Other Surgical Technics: A Systemic Review of Indications and Outcomes of Unilateral Biportal Endoscopic Discectomy from the Current Literature

Objective: Unilateral biportal endoscopic (UBE) spine surgery for spinal diseases has been increasing in popularity because of its favorable outcomes. The goal of this systemic review is to analyze the status of outcomes and complications in lumbar disc herniation during UBE discectomy. Methods: A comprehensive search of the PubMed, Embase, Web of Science, and OVID databases published until June 30, 2021, was performed. The outcomes of interest were indications, operative time, blood loss, hospital stay, complications, visual analog scale score, and Oswestry Disability Index. Results: Seven studies were included in our research. UBE surgery for lumbar stenosis was excluded. A total of 230 patients with lumbar disc herniation were enrolled in the 7 selected studies. The mean operative time was 74.4 minutes, and the mean length of hospital stay was 4.5 days. Mean incidence of complications reported in the 7 articles was 6.2%. UBE showed shorter hospital stays than did microdiscectomy, no significant differences of Oswestry Disability Index or visual analog scale scores, and good recovery rate among other discectomy techniques (microdiscectomy, full endoscopic transforaminal endoscopic lumbar discectomy, and interlaminar endoscopic lumbar discectomy) at 1 month follow-up. Conclusions: Even with the small number of studies and reports analyzed, biases were the main limitation of this analysis; overall, the clinical outcomes and complication rates associated with UBE discectomy were relatively good. It is clear that UBE discectomy is a good treatment choice for lumbar disc herniation, but to prevent unique UBE surgery complications, a clear understanding of the surgical procedures and careful efforts to overcome the learning curve are necessary.restrictio