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서신원(Sin-Won Seo),허윤근(Yun-Kun Huh),이제용(Je-Yong Lee),이창규(Chang-Kyu Lee),배근수(Keun-Soo Bae) 충남대학교 농업과학연구소 2011 농업과학연구 Vol.38 No.1
I/An electro-hydraulic transmission having advantages of convenience, safety, simple linking and high power, and an electronic control system were designed and fabricated. In this study, characteristics of the control system were investigated through outdoor tests for evaluation of installation of the system on a combine. Major findings were as followings. 1. Experiment for performance evaluation of the control system was conducted on concrete road. With steering lever in neutral position, driving HST swash plate and left/right wheel speed increased in proportion to driving lever angle. In case of steering control, steering swash plate angle changed in proportion to steering lever angle. This should cause increase in outer wheel speed, but it was observed that HST swash plate was controlled toward neutral to maintain the speed before steering. As a result, speed before steering was maintained despite the change in outer wheel speed by steering HST swash plate angle change. 2. It was observed that the HST system enabled steering with outer wheel maintained at constant speeds while inner wheel speed decreased, which was more stable than conventional mechanical links. In addition, for the selected 5 criteria, experiment showed satisfactory results and it was judged that installation on real vehicle would be feasible. 3. The control system showed response property of appropriate forward/reverse movement and lift/right steering, without causing any problems during experiment on concrete. Result of response property experiment on field operation also showed appropriate control over forward/reverse movement and left/right steering
The Longitudinal Trend of Cardiac Surgery in Korea from 2003 to 2013
Lee, Kyeong Soo,Kim, Chang Suk,Park, Jong Heon,Hwang, Tae Yoon,Kim, Sang Won,Sim, Sung Bo,Lee, Kun Sei The Korean Society for Thoracic and Cardiovascular 2016 The Korean Journal of Thoracic and Cardiovascular Vol.49 No.sup
Background: The purpose of this study was to investigate longitudinal changes of the utilization of operational and surgical medical care inside and outside a metropolitan area over 10 years, analyzing the residential areas of patients and the locations of medical facilities for major cardiovascular surgery. Methods: Data analysis was conducted by classifying the addresses of patients and the locations of medical care facilities of metropolitan cities and provinces, using data from the National Health Insurance Corporation from January 2003 to December 2013. Results: There is serious concentration of major heart surgery to medical facilities in Seoul; this problem has not improved over time. There were differences in percentages of surgical procedures performed in the metropolitan areas according to major diseases. In the case of Busan and Daegu provinces, at least 50% of the patients underwent surgery in medical facilities in the city, but there are other regions where the percentage is less than 50%. In the case of provinces, the percentage of surgical procedures performed in medical facilities in Seoul or nearby metropolitan cities is very high. Conclusion: Policies to strengthen the regional capabilities of heart surgery and to secure human resources are required to mitigate the concentration of patients in the capital area. Many regional multi-centers must be designated to minimize unnecessary competition among regional university hospitals and activate a win-win partnership model for medical services.
Whoan Jeang Kim,Jae Won Lee,Su Min Kim,Kun Young Park,Shann Haw Chang,Dae Geon Song,Won Sik Choy 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.5
Study Design: Retrospective, single-center study. Purpose: We aimed to determine the perioperative complications of oblique lumbar interbody fusion (OLIF) as a first-stage procedure in combined anterior and posterior operation for adult spinal deformity (ASD) along with sagittal imbalance. Specifically, we aimed to identify the radiological and clinical types of perioperative surgical complications and the factors affecting these complications. Overview of Literature: OLIF has recently gained popularity, and there are several reports of good outcomes and only a few of complications with OLIF; however, a few studies have focused on the perioperative surgical complications of ASD along with sagittal imbalance. Methods: The perioperative period was a 1-week interval between the anterior and posterior procedures. All patients underwent simple radiography and magnetic resonance imaging preoperatively and postoperatively. Cage placement was evaluated for displacement (i.e., subsidence and migration) and vertebral body fracture. Clinical patient complaints were evaluated perioperatively. Student t-test was used for data analysis. Results: A total of 46 patients were included, totaling 138 fusion segments. A week after OLIF, 14 patients/33 segments (30.4%/23.9%) demonstrated endplate injury-associated cage placement change. Subsidence was the most common cage placement-related complication. As compared with patients without endplate injury, those with endplate injuries showed significantly larger correction angles and a higher proportion of them had larger height cages than the disk height in the full-extension lateral view. Although 32.6% of the patients experienced perioperative clinical complications, they were relatively minor and transient. The most common complication was severe postoperative pain (Visual Analog Scale score of >7), and hip flexor weakness spontaneously resolved within 1 week. Conclusions: OLIF yielded more than expected endplate injuries from treatment modalities for ASD along with sagittal imbalance. Therefore, surgeons should be cautious about endplate injury during OLIF procedures. It is difficult to accomplish lordosis correction via OLIF alone; therefore, surgeons should not attempt this impractical correction goal and insert an immoderate cage.
Whoan Jeang Kim,Chang Hyun Ma,Sang Ha Kim,Yeon Seung Min,Jae Won Lee,Shann Haw Chang,Kyung Hoon Park,Kun Young Park,Dae Gun Song,Won Sik Choy 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.4
Study Design: Retrospective study. Purpose: Associations among risk factors related to adjacent segmental disease (ASD) remain unclear. We evaluated the risk factors and segmental lordosis ratio to prevent ASD developing after lumbar spinal fusion. Overview of Literature: Risk factors related to ASD development are age, sex, obesity, pre-existing degeneration, number of fusion segments, and decreased postoperative lumbar lordosis (LL). However, the associations among these factors are still unclear and should be clearly identified. Methods: We retrospectively reviewed data on 274 patients who underwent lumbar spinal fusion of three segments or below for lumbar degenerative disease from January 2010 to December 2012, with over 5 years of follow-up. Patients with preoperative sagittal vertical axis (SVA) >5 cm were excluded due to sagittal imbalance. A total of 37 patients with ASD and 40 control patients (CTRL) were randomly selected in a similar distribution of matching variables: age, sex, and preoperative degenerative changes. Sex, age, number of fusion segments, radiologic measurements, L4–5–S1/L1–S1 LL ratio, and spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], sacral slope [SS], and SVA) were analyzed. Logistic regression was used to analyze the correlation between PI–LL mismatch and L4–5–S1 segmental lordosis rate. Results: No significant difference was found between ASDs and CTRL groups regarding age, sex, number of fusion segments, fusion method, and preoperative and postoperative spinopelvic parameters (PI, SS, PT, and LL). However, regarding the L4–5–S1/L1–S1 lordosis ratio, 50% (p=0.045), 60% (p=0.031), 70% (p=0.042), 80% (p=0.023), and 90% (p=0.023) were statistically significant; <20% (p=0.478), 30% (p=0.223), and 40% (p=0.089) were not statistically significant. In the postoperative PI–LL <10 group, ASD occurred less frequently than in the PI–LL >10 group, and the difference was statistically significant (p=0.048). Conclusions: Patients with a postoperative L4–5–S1/L1–S1 lordosis ratio >50% had less occurrence of ASD. Correcting LL according to PI and physiologic segmental lordosis ratio is important in preventing ASD.