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Hyojune Kim,Si-Jung Song,In-Ho Jeon,Kyoung Hwan Koh 대한견주관절학회 2022 대한견주관절의학회지 Vol.25 No.1
Background: The treatment approach for proximal humeral fractures is determined by various factors, including patient age, sex, dominant arm, fracture pattern, presence of osteoporosis, preexisting arthritis, rotator cuff status, and medical comorbidities. However, there is a lack of consensus in the literature regarding the optimal treatment for displaced proximal humeral fractures. This study aimed to assess and quantify the decision-making process for either conservative or surgical treatment and the choice of surgical method among shoulder surgeons when treating proximal humeral fractures. Methods: Forty sets of true anteroposterior view, scapular Y projection view, and three-dimensional computed tomograms of proximal humeral fractures were provided to 12 shoulder surgeons along with clinical information. Surveys regarding Neer classification, decisions between conservative and surgical treatments, and chosen methods were conducted twice with an interval of 2 months. The factors affecting the treatment plans were also assessed. Results: The inter-rater agreement was fair for Neer classification (kappa=0.395), moderate for the decision between conservative and surgical treatments (kappa=0.528), and substantial for the chosen method of surgical treatment (kappa=0.740). The percentage of agreement was 71.1% for Neer classification, 84.6% for the decision between conservative and surgical treatment, and 96.4% for the chosen method of surgical treatment. The fracture pattern was the most crucial factor in deciding between conservative and surgical treatments, followed by age and physical activity. Conclusions: The decision between conservative and surgical treatment for proximal humeral fractures showed good agreement, while the chosen method between osteosynthesis and arthroplasty showed substantial agreement among shoulder surgeons.
Park, Hyojun,Choi, Hyun-Joon,Hee Min, Chul,Kim, Jung-in IOP 2019 Physics in medicine & biology Vol.64 No.24
<P>The leaf width of a multileaf collimator (MLC) determines the dose conformity to the target volume. The objective of this study was to investigate the feasibility of a two-dimensional dynamic MLC (2DDMLC) to improve the treatment plan quality with a fixed leaf width. The treatment head of the Clinac<SUP>™</SUP> linear accelerator with the Millennium 120<SUP>™</SUP> MLC was modelled with the Geant4 (for GEometry ANd Tracking) tollkit using the Monte Carlo (MC) method. The 2DDMLC produces a beam aperture by moving the MLC bank vertically to the leaf movement. Thus, the effect of the 2DDMLC motion on beam divergence and beam fluence resolution was evaluated by comparing the dose distributions between the conventional MLC motion and the 2DDMLC. Finally, the 2DDMLC was employed for dynamic conformal arc therapy for 13 brain cancer patients. The dose-volumetric parameters, including the dose delivered to 98% of the target volume (<I>D</I> <SUB>98%</SUB>), percent volume given 20% of the prescribed dose (<I>V</I> <SUB>20%</SUB>), and conformity index (CI) were compared with those of the conventional MLC. For the 6 MV beam of the MC model, the depth dose and lateral dose distribution differed by less than 2% between the simulation and measurement. The 2DDMLC did not significantly influence beam divergence and sharpened the beam. In clinical use, the dose delivered to the target was almost identical between the 2DDMLC and conventional MLC (<I>D</I> <SUB>98%</SUB> = 29.74 Gy versus 29.71 Gy, <I>p</I> = 0.18). The CI was improved with the use of the 2DDMLC (CI = 1.49 versus 1.47, <I>p</I> = 0.14). Moreover, irradiation of normal tissue was reduced with the 2DDMLC compared with conventional MLC (<I>V</I> <SUB>20%</SUB> = 17.22% versus 17.45%, <I>p</I> < 0.001). The 2DDMLC improved the dose conformity to the target volume and reduced the irradiation of the normal tissue compared with the conventional MLC.</P>
Polymeric nano-shielded islets with heparin-polyethylene glycol in a non-human primate model
Park, Hyojun,Haque, Muhammad R.,Park, Jae Berm,Lee, Kyo Won,Lee, Sanghoon,Kwon, Yeongbeen,Lee, Han Sin,Kim, Geun-Soo,Shin, Du Yeon,Jin, Sang-Man,Kim, Jae Hyeon,Kang, Hee Jung,Byun, Youngro,Kim, Sung J Elsevier 2018 Biomaterials Vol.171 No.-
<P><B>Abstract</B></P> <P>Intraportal pancreatic islet transplantation incurs huge cell losses during its early stages due to instant blood-mediated inflammatory reactions (IBMIRs), which may also drive regulation of the adaptive immune system. Therefore, a method that evades IBMIR will improve clinical islet transplantation. We used a layer-by-layer approach to shield non-human primate (NHP) islets with polyethylene glycol (nano-shielded islets, NSIs) and polyethylene glycol plus heparin (heparin nano-shielded islets; HNSIs). Islets ranging from 10,000 to 20,000 IEQ/kg body weight were transplanted into 19 cynomolgus monkeys (n = 4, control; n = 5, NSI; and n = 10, HNSI). The mean C-peptide positive graft survival times were 68.5, 64 and 108 days for the control, NSI and HNSI groups, respectively (<I>P</I> = 0.012). HNSI also reduced the factors responsible for IBMIR <I>in vitro</I>. Based on these data, HNSIs in conjunction with clinically established immunosuppressive drug regimens will result in superior outcomes compared to those achieved with the current protocol for clinical islet transplantation.</P>
차량 내부 조향장치 파손방지를 위한 아우터 타이로드의 최적 휨 설계
은효준(Hyojun Eun),신용상(Yongsang Shin),안명훈(Myeonghoon Ahn),정연웅(Yeonwoong Jung),김민준(Minjoon Kim),이문규(Moonkyu Lee),이희갑(Hee-Gab Lee),추용주(YoungJu Chu),이승엽(Seung-Yop Lee) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
In the automobile steering system, Tie-rod acts as a sacrificial part to protect the inner steering gear such as rack and pinion. Therefore, the allowable maximum buckling load is crucial design constraint as well as minimum buckling load. The previous model was recognized to be overdesigned so that it should be remodeled to reduce critical buckling load. In this paper, we showed design method of bent outer Tie-rod giving initial imperfection with eigen buckling mode. However, the bent design brings about mass gain although it makes substantial decrease of critical buckling load. So we set the multi-objective optimizing problem to minimize the value of critical buckling load and mass gain with two kinds of structure design variables – scale factor & bent length. As a result, we obtained the optimum parameters that reduced critical buckling load by 64.96%, and 9.05% mass gain.
상지 관절 기능의 정량적 평가 및 임상적 활용을 위한 스마트폰 기반 운동추적 의료 시스템 개발
정구희(Guhee Jung),김균동(Kyundong Kim),박효준(Hyojun Park),명세현(Sehyun Myung) (사)한국CDE학회 2022 한국CDE학회 논문집 Vol.27 No.4
Because shoulder diseases including the frozen shoulder, rotator cuff disease, and degenerative arthrosis have been rapidly increased, the need to develop a system that can measure quantitatively and objectively has been suggested for achieving the effective exercise and rehabilitation. However, the current method for therapeutic exercise of the shoulder joint consists of the manipulation directly performed by a doctor or physical therapist and self-passive joint movement through patient education. Recently, with the rapid development of information and communication technology (ICT) and combined with rehabilitative medicine, innovative changes are being made in the clinical field. In this paper, we introduce a system that can objectively and quantitatively evaluate the shoulder range of motion. This is a system that utilizes the image processing and server technology of a smartphone without purchasing additional equipment and can be used by himself. The assessment of shoulder motion was performed based on the normal arm and, when involved in both arms, they were evaluated with a single arm. With the development of intuitive UI/UX for this system, we will continue to conduct R&D with the orthopaedic surgeons who were affiliated with the medical university for constructing the raw data and conducting the clinical research.
Hankuk Jeon,Jung Tae Lim,Hui-Dong Qian,Jihoon Park,Hyojun Ahn,Chul-Jin Choi 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
Permanent magnets are increasingly used in transportation technology and sustainable energy production for EVs, hybrid vehicles and wind turbines. High performance permanent magnets, such as Nd-based magnets, have problems with stability at high temperature, supply and high price. Therefore, developing rare-earth free or rare-earth lean permanent magnets is becoming an important task to solve the abovementioned issues. Herein, iron-rich rare-earth alloys with tetragonal ThMn12 structure, which can replace rare earth permanent magnets, is drawing attention due to its high saturation magnetization of 1.43 T, anisotropy field of 10.9 T, and Curie temperature of 800 K. Although the magnetic properties of SmFe12 with ThMn12 structure have been already demonstrated, a number of studies to enhance coercivity are still underway. The coercivity increases as grain sizes approach to the single domain size. Therefore, in this work, we conducted experiments to obtain SmFe12 particles with single domain sized grains to acquire high coercivity through the high energy ball milling and the reduction diffusion process. In this experiment, Sm₂O₃(Samarium Oxide), Fe₂O₃(Iron Oxide), Co, TiO₂(Titanium Dioxide), Ca were used as starting materials. Sm₂O₃ and Ca, as a reducing agent, were excessively added in consideration of vaporization. The starting materials except Ca were crushed and homogeneously mixed for 4 hours using a high energy ball milling process. Then, the powders were processed by low energy ball milling with Ca powder for 2 hours. The resulting mixture was sealed in a graphite crucible and then heat treated in argon atmosphere. This heat treatment process including heat treatment temperature and time were optimized. Then, it was washed using a detergent that dissolves unreacted Ca and remaining CaO, followed by drying in vacuum. It was concluded that the purity of the samples varied with the initial contents of Sm and heat treatment time. The resultant particle size and magnetic properties of the products were also affected by the ball milling conditions. The detailed experimental procedures and physical and magnetic properties will be discussed.