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( Junwon Kim ),( Jang Hun Kim ),( Jong Hyun Kim ),( Taek-hyun Kwon ),( Haewon Roh ) 대한외상학회 2019 大韓外傷學會誌 Vol.32 No.4
Purpose: Cranioplasty (CP) is often required for survival after decompressive craniectomy. Several materials, including autologous bone and various artificial materials, have been introduced for CP, but it remains unclear which material is best for CP. This study aimed to explore differences in complications between patients who underwent CP using an autologous bone flap versus a three-dimensional (3D) titanium mesh and to identify significant risk factors for post-CP complications. Methods: In total, 44 patients were enrolled in this study and divided into two groups (autologous bone vs. 3D titanium mesh). In both groups, various post-CP complications were evaluated. Through a comparative analysis, we aimed to identify differences in complications between the two groups and, using binary logistic analysis, to determine significant factors associated with complications after CP. Results: In the autologous bone flap group, there were three cases of surgical infection (3/24, 12.5%) and 11 cases of bone flap resorption (BFR) (11/24, 45.83%). In the 3D titanium mesh group, there was only one case of surgical infection (1/20, 5%) and 11 cases of various complications, including mainly cosmetic issues (11/20, 55%). A subgroup risk factor analysis of CP with an autologous bone f lap showed no risk factors that predicted BFR with statistical significance, although a marginal association was found between larger bone flaps and BFR (odds ratio [OR]=1.037, p=0.090). In patients treated with a 3D titanium mesh, multivariate analysis revealed that only the existence of a ventriculo-peritoneal shunt system was strongly associated with overall post-CP complications (OR=18.66, p=0.021). Conclusions: Depending on which material was used, different complications could occur, and the rate of complications was relatively high in both groups. Hence, the material selected for CP should be selected based on individual patients’ conditions.
Integrated FEM and CFD Simulation for Off shore Wind Turbine Structural Response
Junwon Seo,William Schaffer,Monique Head,Mehdi Shokouhian,최은수 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.4
This paper implements Finite Element Model (FEM)-enabled computational fl uid dynamic (CFD) analysis to enable wind and wave time-history analysis with multiple force-induced soil–structure-interaction. The soil–structure interaction of steel monopile supported 5 MW wind turbine has been simulated with two common and applicable soil profi les. Lateral soil springs were used according to the American Petroleum Institute (API) Code for p–y curves, while vertical soil springs were generated according to the t–z and q–z API standards. A modal analysis was performed to verify the joint CFD-FEM exhibited a fundamental frequency in the desired range. A verifi cation of the load applications was completed for maximum force and moment under specifi c wind and wave loading parameters. Defl ection results were generated and compared with reliable results published in past studies. Results reveal that a variation in wind speed has a higher impact on soil structure interaction causing a larger defl ection than a variance in the signifi cant wave height. It is also evident that the heterogeneous sand profi le has a high enough stiff ness to cause fatigue damage during extreme multi-hazard loading. It is anticipated that this proposed modeling technique will provide a basis for more accurate application of multi-wind-wave simulations coupled with soil–monopile-interaction.
Mathematical sustainability assessment framework of earthquake-induced steel building population
Junwon Seo,Alan J. Hatlestad,Jung-Han Kimn,Jong Wan Hu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.4
The ability to estimate the probability a building population under seismic events will be sustainable is timely, useful in appropriately allocating earthquake mitigation funds earmarked for repair, rehabilitation, and replacement. A building population is considered sustainable if actual cost incurred is less than a target cost at a given ground motion intensity level such as a certain level of spectral accelerations. The purpose of this study is to construct a mathematical framework coupled with Gompertz and power functions to determine the probability of sustainability of building population subjected to seismic events as a function of target repair-cost ratios. The framework accounts for the exceedence probability of certain earthquake occurrence in 50 years and the fragility data created by joint response surface metamodels (RSMs) and Monte Carlo Simulation (MCS). The fragility data for a population of L-shaped Steel Moment-Frame (LSMF) buildings located in the Central United States and the probability of spectral acceleration exceedence for the target region are used for this study. The probability of sustainability of the LSMF buildings built from pre-1970, between 1970 and 1990, and post-1990 are determined through the developed framework. The mathematical and graphical relationship between the probability of sustainability of the building population under a broad range of spectral accelerations and its target repair-cost ratio are determined. Key findings show that the buildings built in the post-1990 are more sustainable than those built from the pre-1970.
Junwon Choi,윤린 대한설비공학회 2015 International Journal Of Air-Conditioning and Refr Vol.23 No.1
Thermal e±ciencies of Combined Heat and Power (CHP) and Tri-generation system, which areinstalled in a residential district and a general hospital, respectively, are investigated by usingRETScreen. Economic feasibility and amount of CO2 reduction are also estimated by comparingthem with separate energy system, which separately supplies electricity, heating and coolingenergy to consumer. When power generation capacity of the CHP system is changed from 26 to40MW, the e±ciency is the highest at 26MW. It is found that equity payback period is 5.7 years. Power generation capacity of the Tri-generation system for a general hospital was estimated to be3.2MW. Depending on the insulation amount of the building, pro¯ts and operating e±ciency ofthe Tri-generation system are signi¯cantly changed. As an operating strategy, the type of followingelectricity load shows the highest thermal e±ciency of 86%. When cost of electricity israised by 10% and 20% of the present price, simple payback period is reduced from 5.2 years to 3.0and 2.1 years, respectively.
A Method to Detect Object Grasping without Tactile Sensing on a Humanoid Robot
Junwon Jang,Kyungrock Kim,Kicheol Park,Hoseong Kwak,Kyungsik Roh 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
In future daily life, one of the most important functionality as a household service robot may be the delivery task. Furthermore, grasping an object is the essential motion for the delivery task. To complete the ordered delivery task successfully, robot should be able to detect whether its hand is grabbing the target object or not. If the object is released unexpectedly during service, robot has to recognize this abnormal situation properly. Most robots have used tactile sensors in their hands. In this paper, we present a novel method for detecting object grasping for complex hands of a humanoid robot without using tactile sensors. Joint torque values of fingers are exploited as information to predict the states of robotic hands.