Neochordoplasty versus leaflet resection for ruptured mitral chordae treatment: Virtual mitral valve repair

Choi, Ahnryul,McPherson, David D.,Kim, Hyunggun Elsevier 2017 Computers in biology and medicine Vol.90 No.-

<P><B>Abstract</B></P> <P>Degenerative mitral valve (MV) disease involving mitral prolapse is one of the most prevalent MV pathologies. Quadrangular leaflet resection and neochordoplasty demonstrate excellent clinical outcomes for the treatment of posterior leaflet prolapse. We evaluated the functional and biomechanical characteristics of a virtual pathologic MV model suffering from chordal rupture, performed virtual neochordoplasty and quadrangular leaflet resection, and compared the two post-repair MV functions. The pre-repair MV demonstrated severe posterior leaflet prolapse due to the ruptured P2 chordae and excessive stress concentration. Both repair techniques revealed reduced leaflet prolapse, decreased stress concentration, and restored leaflet coaptation. While neochordoplasty demonstrated further improved leaflet coaptation and superior posterior leaflet mobility, leaflet resection showed more uniform leaflet stress distributions. Virtual MV repair simulation has the ability to predict and quantitate biomechanical and functional improvement following MV repair. This strategy has the potential to help determine the most effective repair technique to restore MV function.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A virtual comparative study to evaluate and predict post-repair MV function. </LI> <LI> Comparison of the post-repair (neochordoplasty vs. leaflet resection) MV functions. </LI> <LI> Post-neochordoplasty – improved coaptation and superior posterior leaflet mobility. </LI> <LI> Post-leaflet resection – more uniform leaflet stress distributions. </LI> <LI> Potential of virtual MV repair to help choose the most effective repair technique. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improved determination of dynamic balance using the centre of mass and centre of pressure inclination variables in a complete golf swing cycle

Choi, Ahnryul,Sim, Taeyong,Mun, Joung Hwan Informa UK (TaylorFrancis) 2016 Journal of Sports Sciences Vol.34 No.10

<P>Golf requires proper dynamic balance to accurately control the club head through a harmonious coordination of each human segment and joint. In this study, we evaluated the ability for dynamic balance during a golf swing by using the centre of mass (COM)-centre of pressure (COP) inclination variables. Twelve professional, 13 amateur and 10 novice golfers participated in this study. Six infrared cameras, two force platforms and SB-Clinic software were used to measure the net COM and COP trajectories. In order to evaluate dynamic balance ability, the COM-COP inclination angle, COM-COP inclination angular velocity and normalised COM-COP inclination angular jerk were used. Professional golfer group revealed a smaller COM-COP inclination angle and angular velocity than novice golfer group in the lead/trail direction (P<0.01). In the normalised COM-COP inclination angular jerk, the professional golfer group showed a lower value than the other two groups in all directions. Professional golfers tend to exhibit improved dynamic balance, and this can be attributed to the neuromusculoskeletal system that maintains balance with proper postural control. This study has the potential to allow for an evaluation of the dynamic balance mechanism and will provide useful basic information for swing training and prevention of golf injuries.</P>

Quasi-stiffness of the knee joint in flexion and extension during the golf swing.

Choi, Ahnryul,Sim, Taeyong,Mun, Joung Hwan E. F.N. Spon Ltd 2015 Journal of Sports Sciences Vol.33 No.16

<P>Biomechanical understanding of the knee joint during a golf swing is essential to improve performance and prevent injury. In this study, we quantified the flexion/extension angle and moment as the primary knee movement, and evaluated quasi-stiffness represented by moment-angle coupling in the knee joint. Eighteen skilled and 23 unskilled golfers participated in this study. Six infrared cameras and two force platforms were used to record a swing motion. The anatomical angle and moment were calculated from kinematic and kinetic models, and quasi-stiffness of the knee joint was determined as an instantaneous slope of moment-angle curves. The lead knee of the skilled group had decreased resistance duration compared with the unskilled group (P?<?0.05), and the resistance duration of the lead knee was lower than that of the trail knee in the skilled group (P?<?0.01). The lead knee of the skilled golfers had greater flexible excursion duration than the trail knee of the skilled golfers, and of both the lead and trail knees of the unskilled golfers. These results provide critical information for preventing knee injuries during a golf swing and developing rehabilitation strategies following surgery.</P>

How to quantify the transition phase during golf swing performance: Torsional load affects low back complaints during the transition phase

Sim, Taeyong,Choi, Ahnryul,Lee, Soeun,Mun, Joung Hwan Taylor Francis 2017 Journal of Sports Sciences Vol.35 No.20

Information Processing and Interdisciplinary Technology ; Prediction of Cobb-angle for Monitoring System in Adolescent Girls with Idiopathic Scoliosis using Multiple Regression Analysis

( Eun Ji Seo ),( Ahnryul Choi ),( Seung Eel Oh ),( Hyun Joon Park ),( Dong Jun Lee ),( Joung H Mun ) 한국농업기계학회 2013 바이오시스템공학 Vol.38 No.1

Purpose: The purpose of this study was to select standing posture parameters that have a significant difference according to the severity of spinal deformity, and to develop a novel Cobb angle prediction model for adolescent girls with idiopathic scoliosis. Methods: Five normal adolescents girls with no history of musculoskeletal disorders, 13 mild scoliosis patients (Cobb angle: 10°-25°), and 14 severe scoliosis patients (Cobb angle: 25°-50°) participated in this study. Six infrared cameras (VICON) were used to acquire data and 35 standing parameters of scoliosis patients were extracted from previous studies. Using the AN OVA and post-hoc test, parameters that had significant differences were extracted. In addition, these standing posture parameters were utilized to develop a Cobb-angle prediction model through multiple regression analysis. Results: Twenty two of the parameters showed differences between at least two of the three groups and these parameters were used to develop the multi-linear regression model. This model showed a good agreement (R2 = 0.92) between the predicted and the measured Cobb angle. Also, a blind study was performed using 5 random datasets that had not been used in the model and the errors were approximately 3.2 ± 1.8. Conclusions: In this study, we demonstrated the possibility of clinically predicting the Cobb angle using a non-invasive technique. Also, monitoring changes in patients with a progressive disease, such as scoliosis, will make possible to have determine the appropriate treatment and rehabilitation strategies without the need for radiation exposure.

Safety evaluation and consideration of 4 Pin Multi-needle for meso-therapy

Kim, Jun-Tae,Choi, Ahnryul,Jeong, Jin-Hyoung,Jo, Jae-Hyun,Ryu, Ok-Su,Kim, Eun-Ji,Kim, Ki-Young,Song, Mi-Hee,Song, Young-Ho,Shin, Woon-Seob,Lee, Sang-Sik IOS Press 2018 Technology and health care Vol.26 No.1

<P>This study was conducted according to the method presented in the Republic of Korea Pharmacopoeia 11th Revision, aseptic test method to evaluate the suitability of sterilization for a sterile needle (4 Pin Multi-needle). In this study, four tests were conducted: sterility test, cytotoxicity test, acute toxicity test, skin sensitization test. First, in the aseptic test, the microorganism was not proliferated in the aseptic test of the medium. As a result of the performance test of the medium, it was confirmed that the microorganism developed within 3 days and the fungus was evident within 5 days. Based on this, it was confirmed that the medium was suitable, and as a result of the aseptic test, the development of microorganisms was not observed during the total culture period. Based on these results, tests were conducted which were confirmed to be suitable for aseptic testing because the development of bacteria on the provided samples was not recognized. For cytotoxicity tests ISO10993-5; 2009 (Biological Evaluation of Medical Devices, Part 5: Test for <I>in vitro</I> Cytotoxicity). As a result, the MEM eluate of the test substance caused very slight cytotoxicity to the fibroblasts of the mouse and was judged to be Grade 1 (Slightly cytotoxic) according to the judgment standard of ISO 10993-5. On the other hand, solvent control, negative control and positive control showed the expected results on the test. Acute Toxicity Test Results: It was judged that there was no systemic toxicity change when ICR mice were treated with 50 mL/kg B.W. of the eluate of sterile injectable needle for 72 hours. Skin sensitization test result: The Hartley guinea pig was evaluated as a substance which is evaluated as a substance which does not induce any skin reaction when skin sensitization is applied to the dissected material of the sterile injectable needle and is weak in skin sensitivity. Based on the above tests, we will study the stability and efficacy of more reliable medical devices based on the verification and performance of medical devices.</P>

생체역학 기반 농작업 부담 평가 웨어러블 시스템 개발

정현우(Hyunwoo Jung),최안렬(Ahnryul Choi),문정환(Joung Hwan Mun) 대한인간공학회 2022 대한인간공학회 학술대회논문집 Vol.2022 No.10

Prediction of Cobb-angle for Monitoring System in Adolescent Girls with Idiopathic Scoliosis using Multiple Regression Analysis

Seo, Eun Ji,Choi, Ahnryul,Oh, Seung Eel,Park, Hyun Joon,Lee, Dong Jun,Mun, Joung H. Korean Society for Agricultural Machinery 2013 바이오시스템공학 Vol.38 No.1

Purpose: The purpose of this study was to select standing posture parameters that have a significant difference according to the severity of spinal deformity, and to develop a novel Cobb angle prediction model for adolescent girls with idiopathic scoliosis. Methods: Five normal adolescents girls with no history of musculoskeletal disorders, 13 mild scoliosis patients (Cobb angle: $10^{\circ}-25^{\circ}$), and 14 severe scoliosis patients (Cobb angle: $25^{\circ}-50^{\circ}$) participated in this study. Six infrared cameras (VICON) were used to acquire data and 35 standing parameters of scoliosis patients were extracted from previous studies. Using the ANOVA and post-hoc test, parameters that had significant differences were extracted. In addition, these standing posture parameters were utilized to develop a Cobb-angle prediction model through multiple regression analysis. Results: Twenty two of the parameters showed differences between at least two of the three groups and these parameters were used to develop the multi-linear regression model. This model showed a good agreement ($R^2$ = 0.92) between the predicted and the measured Cobb angle. Also, a blind study was performed using 5 random datasets that had not been used in the model and the errors were approximately $3.2{\pm}1.8$. Conclusions: In this study, we demonstrated the possibility of clinically predicting the Cobb angle using a non-invasive technique. Also, monitoring changes in patients with a progressive disease, such as scoliosis, will make possible to have determine the appropriate treatment and rehabilitation strategies without the need for radiation exposure.

A Comparison of the Effects of Worker-Related Variables on Process Efficiency in a Manufacturing System Simulation

Lee, Dongjune,Park, Hyunjoon,Choi, Ahnryul,Mun, Joung H. Korean Society for Agricultural Machinery 2013 바이오시스템공학 Vol.38 No.1

Purpose: The goal of this study was to build an accurate digital factory that evaluates the performance of a factory using computer simulation. To achieve this goal, we evaluated the effect of worker-related variables on production in a simulation model using comparative analysis of two cases. Methods: The overall work process and worker-related variables were determined and used to build a simulation model. Siemens PLM Software's Plant Simulation was used to build a simulation model. Also, two simulation models were built, where the only difference was the use of the worker-related variable, and the total daily production analyzed and compared in terms of the individual process. Additionally, worker efficiency was evaluated based on worker analysis. Results: When the daily production of the two models were compared, a 0.16% error rate was observed for the model where the worker-related variables were applied and error rate was approximately 5.35% for the model where the worker-related variables were not applied. In addition, the production in the individual processes showed lower error rate in the model that included the worker-related variables than the model where the worker-related variables were not used. Also, among the total of 22 workers, only three workers satisfied the IFRS (International Financial Reporting Standards) suggested worker capacity rate (90%). Conclusions: In the daily total production and individual process production, the model that included the worker-related variables produced results that were closer to the real production values. This result indicates the importance of worker elements as input variables, in regards to building accurate simulation models. Also, as suggested in this study, the model that included the worker-related variables can be utilized to analyze in more detail actual production. The results from this study are expected to be utilized to improve the work process and worker efficiency.

인공지능 및 인솔형 센싱 장치를 활용한 인체 중력중심 추정

문호세(Jose Moon),허현무,최안렬(Ahnryul Choi),문정환(Joung Hwan Mun) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6

본 논문은 스마트 깔창을 활용한 보행 중 인체 중력중심 예측 알고리즘 개발을 목표로 한다. 스마트 깔창에 부착된 압력센서의 값을 입력으로 하여 구성된 인공지능 알고리즘에 의해 보행 시 인체의 중력중심을 예측한다. 인공지능 알고리즘은 상관계수 0.9 이상, RMSE 95mm 이하의 결과를 보였다. 예측된 인체의 중력중심을 기반으로 깔창 사용자의 병리학적 보행 메커니즘을 간편하게 분석할 수 있는데 도움을 줄 수 있다.