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차종현,김태환,배지열,김태일,정대윤,조형희,Cha, Jong Hyun,Kim, Taehwan,Bae, Ji-Yeul,Kim, Taeil,Jung, Daeyoon,Cho, Hyung Hee 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.4
Stealth technology of combat aircraft is most significant capability in recent air battlefield. As the detector of IR missiles is being developed, IR stealth capability which is evaluated by IR signature level become more important than it was in previous generation. Among IR signature of aircraft from various sources, aerodynamic heating dominates in long-wavelength IR spectrum of $8{\sim}12{\mu}m$. Skin temperature change by aerodynamic heating which is derived by effects of Mach number and structure. The 4th and 5th generation aircraft are selected for calculation of the skin temperature, and its height and velocity in numerical conditions are 10,000 m and Ma 0.9~1.9 respectively. Aircraft skin temperature is calculated by computing convection of fluid and conduction, convection and radiation of surface. As the aircraft accelerates to higher Mach number, maximum skin temperature increases more rapidly than average temperature and temperature distribution changes in more sharp, interactive ways. The 4th generation aircraft whose shape is more complex than that of the 5th generation aircraft have complicated temperature distribution. On the other hand, the 5th generation aircraft whose shape is relatively simple shows plain temperature distribution and lower skin temperature in terms of both average and maximum value.
Sol-Gel 반응을 통한 Surlyn/유기 실리케이트 나노복합재료 제조 및 물성에 관한 연구
차종현,정희정,서길수 한국공업화학회 2003 응용화학 Vol.7 No.2
Transparent organic-inorganic hybrid material was synthesized via the sol-gel method using polyethylene-co-methacrylic acid(PEMA) ionomer and a metal alkoxide, tetraethylorthosilicae(TEOS). The resulting material was characterized using ^(29)Si solid-state nuclear magnetic resonance spectroscopy results prove that silica is formed via the sol-gel reaction. Scanning electron microscopy analysis (SEM) , transmission electron microscopy (TEM) studies indicate that silica particle size is in nanoscopic level (70nm average size), and silica nanoparticles are uniformly dispersed in the polymer matrix after the sol-gel process. Theremogravimetric analysis (TGA) results show that the silica content of the hybrid. The thermal stability of the ionomer increases after hybridization. Material testing machine of the hybrid shows that the stress of ionomer increase after the sol-gel reaction.
차종현,문명호,이용해,고인창,김규남,김창균,김훈 대한성형외과학회 2017 Archives of Plastic Surgery Vol.44 No.1
Background The purpose of this study was to assess the correlation between the 2-dimensional (2D) extent of orbital defects and the 3-dimensional (3D) volume of herniated orbital content in patients with an orbital wall fracture. Methods This retrospective study was based on the medical records and radiologic data of 60 patients from January 2014 to June 2016 for a unilateral isolated orbital wall fracture. They were classified into 2 groups depending on whether the fracture involved the inferior wall (group I, n=30) or the medial wall (group M, n=30). The 2D area of the orbital defect was calculated using the conventional formula. The 2D extent of the orbital defect and the 3D volume of herniated orbital content were measured with 3D image processing software. Statistical analysis was performed to evaluate the correlations between the 2D and 3D parameters. Results Varying degrees of positive correlation were found between the 2D extent of the orbital defects and the 3D herniated orbital volume in both groups (Pearson correlation coefficient, 0.568–0.788; R2=32.2%–62.1%). Conclusions Both the calculated and measured 2D extent of the orbital defects showed a positive correlation with the 3D herniated orbital volume in orbital wall fractures. However, a relatively large volume of herniation (>0.9 cm3) occurred not infrequently despite the presence of a small orbital defect (<1.9 cm2). Therefore, estimating the 3D volume of the herniated content in addition to the 2D orbital defect would be helpful for determining whether surgery is indicated and ensuring adequate surgical outcomes.
차종현,이용해,Wan Chul Ruy,Young Roe,문명호,정성균 대한두개안면성형외과학회 2016 Archives of Craniofacial Surgery Vol.17 No.3
Background: Restoring the orbital cavity in large blow out fractures is a challenge for surgeons due to the anatomical complexity. This study evaluated the clinical outcomes and orbital volume after orbital wall fracture repair using a rapid prototyping (RP) technique and intraoperative navigation system. Methods: This prospective study was conducted on the medical records and radiology records of 12 patients who had undergone a unilateral blow out fracture reconstruction using a RP technique and an intraoperative navigation system from November 2014 to March 2015. The surgical results were assessed by an ophthalmic examination and a comparison of the preoperative and postoperative orbital volume ratio (OVR) values. Results: All patients had a successful treatment outcome without complications. Volumetric analysis revealed a significant decrease in the mean OVR from 1.0952±0.0662 (ranging from 0.9917 to 1.2509) preoperatively to 0.9942±0.0427 (ranging from 0.9394 to 1.0680) postoperatively. Conclusion: The application of a RP technique for the repair of orbital wall fractures is a useful tool that may help improve the clinical outcomes by understanding the individual anatomy, determining the operability, and restoring the orbital cavity volume through optimal implant positioning along with an intraoperative navigation system.
실도로 주행 데이터를 이용한 도로 인프라 센서 기반 차선 변경 거동 검출 네트워크 연구
차종현,이태현,송봉섭 한국자동차공학회 2022 한국 자동차공학회논문집 Vol.30 No.10
In this paper, a classification algorithm of lane change maneuver based on roadside sensors on highway is proposed. Data augmentation using field operational test data is also considered for scalability. The maneuver classification is composed of semantic maps and convolution neural network(CNN). The semantic map aims to represent a bird’s eye view of both vehicle and road geometry, and the corresponding trajectory of the vehicle. The CNN is used to classify a lane change maneuver of multiple vehicles. While good performance of maneuver classification is shown with respect to a well-known dataset called highD, it is still necessary to consider scalability. Thus, the data augmentation is suggested to build a semantic map based on field operational test data. Despite different sensor characteristics of two datasets, it is demonstrated how the performance of CNN-based maneuver classification is improved in terms of scalability is demonstrated.