• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.177-185
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• 2000

The deformation characteristics is one of the major factors to resume the crash configuration in collision accident reconstruction. Crash analysis are carried out using finite element method and body stiffness equations representing force-deformation relationship are derived, Two different crash conditions : 1) frontal barrier impact 2) frontal impact between cars are given for the derivation of the equations. The stiffness coefficient of equation by method 2) is larger than that by method. 1). Crash analysis between two vehicles is accomplished with three crash angles and three velocities for each angle condition. The deformations are measured for six selected points and deformation energies are calculated using the derived equations. Equation by method 2) results in better estimation of deformation energy than that by method 1) for all crush configurations. The estimated energies can be utilized as one of indices to identify the type of the collision accident result.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1183-1192
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• 1989

본 논문에서는 평면변형률 상태하에서 안정하게 성장하는 균열선단에 집중 되어있는 강소성역의 해석에 역점을 두어 재결정법과 탄.소성유한요소법을 도입하여 안정 성장균열 선단에 형성되는 균열 성장저항에 직접적인 영향을 미치고 있는 소성 역의 크기나 형태에 대한 실험 및 해석을 하였다.

• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.205-213
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• 2021

Objective: The aim of this study was to analyze body stability Joint coordination pattern though as bending stiffness of shoes during stance phase of running. Method: 47 male subjects (Age: 26.33 ± 2.11 years, Height: 177.32 ± 4.31 cm, Weight: 65.8 ± 3.87 kg) participated in this study. All subjects tested wearing the same type of running shoes by classifying bending stiffness (A shoes: 3.2~4.1 N, B shoes: 9.25~10.53 N, C shoes: 20.22~21.59 N). They ran 10 m at 3.3 m/s (SD ±3%) speed, and the speed was monitored by installing a speedometer at 3 m intervals between force plate, and the measured data were analyzed five times. During running, ankle joint, MTP joint, coupling angle, inclination angle (anterior-posterior, medial-lateral) was collected and analyzed. Vector coding methods were used to calculate vector angle of 2 joint couples during running: MTP-Ankle joint frontal plane. All analyses were performed with SPSS 21.0 and for repeated measured ANOVA and Post-hoc was Bonferroni. Results: Results indicated that there was an interaction between three shoes and phases for MTP (Metatarsalphalangeal) joint angle (p = .045), the phases in the three shoes showed difference with heel strike~impact peak (p1) (p = .000), impact peak~active peak (p2) (p = .002), from active peak to half the distance to take-off until take-off (p4) (p = .032) except for active peak~from active peak to half the distance to take-off (p3) (p = .155). ML IA (medial-lateral inclination angle) for C shoes was increased than other shoes. The coupling angle of ankle angle and MTP joint showed that there was significantly difference of p2 (p = .005), p4 (p = .045), and the characteristics of C shoes were that single-joint pattern (ankle-phase, MTP-phase) was shown in each phase. Conclusion: In conclusion, by wearing high bending stiffness shoes, their body instability was increased during running.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.475-482
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• 2010

In this paper, an efficient two-level parallel domain decomposition algorithm is suggested to solve large-DOF structural problems. Each subdomain is composed of the coarse problem and local problem. In the coarse problem, displacements at coarse nodes are computed by the iterative method that does not need to assemble a stiffness matrix for the whole coarse problem. Then displacements at local nodes are computed by Multi-Frontal Sparse Solver. A parallel version of PCG(Preconditioned Conjugate Gradient Method) is developed to solve the coarse problem iteratively, which minimizes the data communication amount between processors to increase the possible problem DOF size while maintaining the computational efficiency. The test results show that the suggested algorithm provides scalability on computing performance and an efficient approach to solve large-DOF structural problems.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.220-227
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• 1998

In substitution of beam-nonlinear spring model for real-car, it may have errors due to complicated characteristics of joint and overestimation of joints stiffness. In this research, a method for the joint modeling was suggested by nonlinear static and dynamic analyses of beam and shell joint models and verified by the application of accomplished joint modeling method to simplified full car model. In consequence, modified simplified full car model was improved in local acceleration and rigid wall force. Finally, the frontal crash analyses with the dummy were established and the accelerations of accelerations of head, chest and pelvis had good agreements with those of shell model.

• Transactions of Materials Processing
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• v.24 no.2
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• pp.130-137
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• 2015

This paper presents the development process of automotive side door impact beam for passenger cars. Weight reduction while maintaining functional requirements is one of the major goals in the automotive industry. In this study, thin-walled side door beam using quenchable boron steel was designed to reduce the weight of conventional side door tubular one. In order to estimate design for the proposed side door beams, the static side impact protection tests(FMVSS 214) were conducted using the finite element method. Based on the simulation results, geometry modification of the side door beam has been performed via creating new reinforcing ribs. Furthermore, the manufactured frontal impact beam was mounted on the real side door of a passenger car, and then static impact protection test carried out. It is concluded that the presented test results can provide significant contribution to the stiffness of side door impact beams and light-weighting door research.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.249-257
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• 2022

This paper presents an improved computational framework for the direct-solution-based finite element tearing and interconnecting (FETI) algorithm. The FETI-local algorithm is further improved herein, and localized Lagrange multipliers are used to define the interface among its subdomains. Selective inverse entry computation, using a property of the Boolean matrix, is employed for the computation of the subdomain interface stiffness and load, in which the original FETI-local algorithm requires a full matrix inverse computation of a high computational cost. In the global interface computation step, the original serial computation is replaced by a parallel multi-frontal method. The performance of the improved FETI-local algorithm was evaluated using a numerical example with 64 million degrees of freedom (DOFs). The computational time was reduced by up to 97.8% compared to that of the original algorithm. In addition, further stable and improved scalability was obtained in terms of a speed-up indicator. Furthermore, a performance comparison was conducted to evaluate the differences between the proposed algorithm and commercial software ANSYS using a large-scale computation with 432 million DOFs. Although ANSYS is superior in terms of computational time, the proposed algorithm has an advantage in terms of the speed-up increase per processor increase.

• Journal of Acupuncture Research
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• v.17 no.1
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• pp.1-12
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• 2000

Ge-Fu(歌賦) means prose and poetry individually, and they both have a meaning of all the rhythmical poetrical compositions making it ease for people to remember the content. All the Ge-Fus used in oriental medicine are made in Yuan(元), Mine(明)and Qing(靑)dynasty, and they have been largely used in most of all the fields of medicine such as Ben-Cao(本草), Tang-Ye(湯液), Zhen-Jiu(鍼灸), Zhen-Duan(診斷). Zhen-Jiu-Ge-Fu(鍼灸歌賦) has about 90 poetries and 10 proses and they contain the names of meridian; courses of meridian streams; accurate positions of acupuncture points; functions; effects; meanings of the name of acupuncture points; usages and effects of special points; manipulations of reinforcing and reducing method; contraindications of acupuncturing; principles of selections and orders of acupuncture points in therapy; and eight diadgoses. Zhen-Jiu-Ge-Fu is subdivided into Jing-Xue(經穴歌), Zhi-Jiu-Ge(刺灸歌), Shu-Xue-Ge(輸穴歌), Zhi-Liao-Ge(治療歌). And In Zhi-Liao-Ge, the most brief and essential Ge-Fu-Si-Zong-Sue-Ge- contains theraputic designs using far apart acpuncture points from the right painful areas in the body. In this study, the author opinionated the Si-Zong-Sue-Ge can be the prototype of the distant needling; the research on this can open the importance of Ge-Fus. On conclusion, 1. "Upper and lower Abdomen - Zu-San-Li($S_{36}$) (肚腹三里留)" means when there are problems and disorders in upper and lower abdomen, distinctively, such as gastric pain, maldigestion, flatulence, abdominal pain, constipation, diarrhea, vomiting, menstrual disorer, knee pain and tonic functioning, 족삼리 can be a right choice for distant needling point for treating. 2. "Face and Eye-He-Gu($Li_4$) (面目合谷收)" means when there are problems and disorders in facial, eye, ear, nose, throat, mouth regions, distinctively, such as facial edema, toothache, headache, sore throat, rhinorrhea, frontal headache, abdominal pain, dizziness, He-Gu can be a right choice for distant needling point for treating. 3. "Upper and lower back - Wei-Zhong($B_{40}$) (腰背委中求)" means when there are problems and disorders in upper and lower back, distinctively, such as upper back pain, lumbargo, hamstring muscle pain, popliteal region pain, lower extremity compartment syndrom, Inguinal region pain, muscle twitch, vomiting and diarrhea, hemorrhoidal bleeding, skin rash, Wei-Zhong can be a right choice for distant needling point for treating. 4. "Head and neck - Lie-Que($L_7$) (頭項審列缺)" means when there are problems and disorders in capital and nuchal area, distinctively, such as migraine, frontal headache, rhinorrhea, asthmatic dyspnea, aphasia, coughing, neck stiffness, occipital headache, upper extremity pain, Lie-Que can be a right choice for distant needling point for treating.