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준 폐만 점착성 퇴적물의 퇴적매개변수 산정에 관한 실험적 연구
정의택(Jung, Eui-Taek),김용묵(Kim, Yong-Muk),김동호(Kim, Dong-Ho),황규남(Hwang, Kyu-Nam) 한국해안해양공학회 2012 한국해안해양공학회 논문집 Vol.24 No.3
본 연구에서는 환형수조를 이용한 일련의 퇴적실험을 수행하여, 국내 최초로 자연 점착성 퇴적물 시료에 대한 퇴적 매개변수가 정량적으로 산정되었다. 퇴적실험을 위해 광양만이 대표 해역으로 선정되어 시료가 채취되었으며, 퇴적실험은 초기농도가 동일한 조건에서 바닥전단응력의 크기만을 변화시키면서 총 18회의 실험이 수행되었다. 퇴적실험결과, 광양만 갯벌 점착성 퇴적물의 최소전단응력 τ<sub>bmin</sub> 과 퇴적률 매개변수들 σ₁, τ<sub>b</sub>b* ?1)<sub>50</sub>은 각각 0.11N/m², 0.68, 0.85로 산정되었으며, 과거 타 연구결과와의 비교검토를 통하여 본 실험에서 도출된 결과의 타당성이 입증되었다. In this study, a series of deposition tests have been performed using an annular flume and depositional parameters of natural cohesive sediments have been estimated domestically for the first time. The natural cohesive sediments for deposition tests have been collected from Kwangyang Bay and total 18 deposition tests have been carried out on different bed shear stress respectively but with the same initial concentration. Test results for natural cohesive sediments of Kwangyang bay show that minimum bed shear stress τ<sub>bmin</sub> , standard deviation σ₁, and time scale parameter τ<sub>b</sub>b* ?1)<sub>50</sub> are 0.11N/m², 0.68 and 0.85, respectively. Through the comparison with results of previous studies for other sediments, the results of this study are shown to be good enough to verify.
Eui-Sun Jeong,Hye Kyung Jung,Ju-Ran Byeon,Ayoung Lee,Ji Taek Hong,Seong Eun Kim,Chang Mo Moon 대한상부위장관ㆍ헬리코박터학회 2023 Korean Journal of Helicobacter Upper Gastrointesti Vol.23 No.1
Background/Aims: Esophageal perforation is associated with high mortality and morbidity in patients presenting to the emergency department (ED) with esophageal injury. We investigated the effectiveness of initial CT scan in patients with esophageal injury to determine the risk factors for complications. Methods: Patients admitted through the ED for evaluation of esophageal injuries between January 2001 and May 2020, were investigated. Demographic data, etiological factors, comorbidities, treatment administered, and outcomes were collected. Esophageal injury was graded based on the following CT criteria: (a) normal, (b) pneumomediastinum, (c) mediastinitis, fluid collection, abscess, or overt esophageal wall injury, and (d) pleural effusion, subcutaneous emphysema, or pneumothorax. Grade 2 was defined as microperforation and grades 3 and 4 as overt perforation. Results: Of 281 patients with esophageal injury, 38 had CT-documented overt perforations and 20 had microperforations. Foreign body-induced injury (n=37), Boerhaave syndrome (n=12), and chemical injury (n=3) were common causes of esophageal injury. Complications occurred in 24 (8.5%) patients. Risk factors for complications were age ≥65 years (OR 4.14, 95% CI 1.18~14.56, P=0.027), cerebrovascular disease (OR 8.58, 95% CI 1.13~65.19, P=0.038), Boerhaave syndrome (OR 12.52, 95% CI 2.07~75.68, P=0.006), chemical injury (OR 15.72, 95% CI 3.67~67.28, P<0.001), and CT-documented grade 4 perforation (OR 15.75, 95% CI 4.39~56.55, P<0.001). Conclusions: Initial CT-based grading in the ED are useful for predicting potential complications and for managing patients with esophageal injury and suspected perforation.
Eui Yub Jung,In Taek Oh,Sang Yeup Shim,Byung-Ho Yoon,성열보 대한정형외과학회 2019 Clinics in Orthopedic Surgery Vol.11 No.1
Background: The purpose of this study was to evaluate the quantitative association between the degree of reduction and the position of the blade of the proximal femoral nail antirotation (PFNA) in intertrochanteric hip fractures. Methods: From March 2009 to April 2015, 530 patients treated with PFNA for intertrochanteric hip fractures were retrospectively reviewed. Patients were divided into a valgus reduced group (group 1) and a non-valgus reduced group (group 2), and the “valgus reduced” was defined as valgus reduction over 5°. We compared the calcar referenced tip-apex distance (calTAD) and the area between the blade of PFNA and the medial cortex of the femoral neck between the two groups. Results: The calTAD was measured as 22.5 ± 4.1 mm in group 1 and 24.8 ± 3.8 mm in group 2 (p < 0.05). The area between the blade and the medial femoral neck was measured as 135.5 ± 49.8 mm2 in group 1 and 145.1 ± 54.8 mm2 in group 2 (p = 0.074). The area corrected for the length difference in the femoral neck was 0.55 ± 0.16 in group 1 and 0.79 ± 0.19 in group 2 (p < 0.05). Conclusions: Valgus reduction resulted in less calTAD and inferior position of the blade at the femoral neck in the treatment of intertrochanteric hip fractures with PFNA.
Synthetic Test Circuit for Thyristor Valve in HVDC Converter with New High-Current Source
Eui-Cheol Nho,Byung-Moon Han,Yong Ho Chung,Seung Taek Baek,Jae-Hun Jung IEEE 2014 IEEE transactions on power electronics Vol.29 No.7
<P>Synthetic test circuit (STC) for thyristor valve test consists of a low-voltage high-current source to provide the forward current during turn-on state and a low-current high-voltage source to provide the reverse and forward voltage during turn-off state. This paper proposes a new low-voltage high-current source for STC that has a six-pulse thyristor converter and a two-phase chopper with an auxiliary switch. The operation of STC with a new low-voltage high-current source was verified through theoretical analysis and computer simulations with PSCAD/EMTDC. Based on computer simulation results, a scaled hardware system for the proposed circuit was built and tested to confirm the feasibility of implementing a real-size STC.</P>