• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.6
• /
• pp.431-437
• /
• 2017

In this study, based on the RPS algorithm, the application results to an electrically controlled suspension system using previewed road information are presented. Reducing the excessive vibration induced by a disturbance transmitted to the system and secure its stability is a major issue. In particular, in the automotive industry, the demand is constantly being raised. A typical external disturbance causing vibration and instability of a vehicle is an irregular roadway surface that contacts a running vehicle tire. Therefore, obtaining such profile information is an important process. The RPS algorithm using a multi sensor system was constructed and implemented in a real car. Through experimental work using the RPS system included non-contact type optical sensors, it could robustly reconstruct the road input profiles from the intermixed data onto the vehicle's dynamic motion while traveling at an uneven roadway surface. A controller with a preview control was designed in the framework of a semi-active suspension system based on the 7 degrees of freedom full vehicle model. The control performance of the system was evaluated through simulations and the results were compared with the passive vehicle condition. These results highlight the feasibility of the presented control frame.

• Journal of the Korean Arthroscopy Society
• /
• v.13 no.3
• /
• pp.254-258
• /
• 2009

Tibial eminence fracture is caused by distortion, excessive flexion and extension, varus and valgus injury of the knee joint in the form of avulsion fracture. A failure over the exact anatomical reduction of fragment can lead to instability and limitation of joint motion. Recently, a variety of arthroscopic assisted reduction and fixation technique have been used. In the tibial eminence fracture, we created an arthroscopic pull-out wire fixation technique using a cannulated screw that is easy and more convenient than in the conventional technique. So we report this technique with a review of current literatures.

• Journal of Korean Medicine Rehabilitation
• /
• v.29 no.4
• /
• pp.117-126
• /
• 2019

To evaluate the effects of Korean medicine and Chuna treatment on patient with pain and limited range of motion (ROM) after scapular fracture. Patient was treated with Chuna manual therapy, acupuncture, herbal medicine, pharmacoacpuncture, cupping therapy and measured by ROM, visual analog scale (VAS), shoulder pain and disability index (SPADI), American shoulder elbow surgery scale (ASES), Korean shoulder score for instability (KSS). After the 3 weeks treatment, the patient's ROM, VAS, SPADI, ASES, KSS scores were improved. Rehabilitation program including Chuna manual therapy can be effectively used to improve scapular fracture patient's pain and symptom during rehabilitation period. Therefore it is recommended to use Chuna manual therapy for the improvement of movement and pain from fracture.

• Korean Journal of Applied Biomechanics
• /
• v.31 no.3
• /
• pp.155-161
• /
• 2021

Objective: There is a lack of studies using the 3D-2D image registration techniques on the mechanism of a shoulder injury for ice hockey players. This study aimed to analyze in vivo 3D glenohumeral joint arthrokinematics in collegiate ice hockey athletes and compare shoulder scaption with or without a hockey stick using the 3D-2D image registration technique. Method: We recruited 12 male elite ice hockey players (age, 19.88 ± 0.65 years). For arthrokinematic analysis of the common shoulder abduction movements of the injury pathogenesis of ice hockey players, participants abducted their dominant arm along the scapular plane and then grabbed a stick using the same motion under C-arm fluoroscopy with 16 frames per second. Computed tomography (CT) scans of the shoulder complex were obtained with a 0.6-mm slice pitch. Data from the humerus translation distances, scapula upward rotation, anterior-posterior tilt, internal to external rotation angles, and scapulohumeral rhythm (SHR) ratio on glenohumeral (GH) joint kinematics were outputted using a MATLAB customized code. Results: The humeral translation in the stick hand compared to the bare hand moved more anterior and more superior until the abduction angle reached 40°. When the GH joint in the stick hand was at the maximal abduction of the scapula, the scapula was externally rotated 2~5° relative to 0°. The SHR ratio relative to the abduction along the scapular plane at 40° indicated a statistically significant difference between the two groups (p < 0.05). Conclusion: With arm loading with the stick, the humeral and scapular kinematics showed a significant correlation in the initial section of the SHR. Although these correlations might be difficult in clinical settings, ice hockey athletes can lead to the movement difference of the scapulohumeral joints with inherent instability.

• Geomechanics and Engineering
• /
• v.19 no.1
• /
• pp.49-60
• /
• 2019

Crack instability propagation during coal and rock mass failure is the main reason for electromagnetic radiation (EMR) generation. However, original cracks on coal and rock mass are hard to study, making it complex to reveal EMR laws and mechanisms. In this paper, we prefabricated cracks of different inclinations in coal and rock samples as the analogues of the native cracks, carried out uniaxial compression experiments using these coal and rock samples, explored, the effects of the prefabricated cracks on EMR laws, and verified these laws by measuring the surface potential signals. The results show that prefabricated cracks are the main factor leading to the failure of coal and rock samples. When the inclination between the prefabricated crack and axial stress is smaller, the wing cracks occur first from the two tips of the prefabricated crack and expand to shear cracks or coplanar secondary cracks whose advance directions are coplanar or nearly coplanar with the prefabricated crack's direction. The sample failure is mainly due to the composited tensile and shear destructions of the wing cracks. When the inclination becomes bigger, the wing cracks appear at the early stage, extend to the direction of the maximum principal stress, and eventually run through both ends of the sample, resulting in the sample's tensile failure. The effect of prefabricated cracks of different inclinations on electromagnetic (EM) signals is different. For samples with prefabricated cracks of smaller inclination, EMR is mainly generated due to the variable motion of free charges generated due to crushing, friction, and slippage between the crack walls. For samples with larger inclination, EMR is generated due to friction and slippage in between the crack walls as well as the charge separation caused by tensile extension at the cracks' tips before sample failure. These conclusions are further verified by the surface potential distribution during the loading process.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.6
• /
• pp.422-428
• /
• 2019

A tailless or Blended-Wing-Body(BWB) shaped configuration is highlighted for UCAV with low RCS characteristics. The BWB configuration is characterized by its directional static instability and low controllability. To control the directional movement of the BWB configured vehicle, directional thrust vectoring equipment or drag rudder typed control surfaces which utilize the drag differences of the wing can be considered. This paper deals with a BWB shaped configuration using a spoiler and describes the lateral-directional aerodynamic characteristics of the vehicle. In addition, it is shwon that the lateral-directional motion can be controlled effectively by using the classical PI control structure. This control law is verified by flight test and showed adequate for the tailless BWB shaped UAV.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.48.4-48.4
• /
• 2019

We studied the metal-distribution of isolated Milky-way mass galaxy using various hydrodynamic solvers and investigated the difference of the result between AMR and SPH codes. In particle-based codes, physical quantities like mass or metallicity defined in each particle are conserved unless being injected explicitly by the effect of the supernova, whereas in the Eulerian codes the diffusion is simply accomplished by hydro-equation. Therefore, without including explicit physics of diffusion on the SPH- codes, the metal mixing in the galaxy or CGM only can be accomplished by the direct motion of the particles, however, the standard-SPH codes depress the instability of the turbulent fluid mixing. In this work, we simulated under common initial conditions, common gas-physics like cooling-heating models, and star-formation feedback using ENZO(AMR) GIZMO and GADGET-2 codes. We additionally included a metal-diffusion algorithm on the SPH-codes, which follows the subgrid-turbulent mixing model investigated by Shen et al. (2010) and compared the effect of the metal-outflow on the halo region of the galaxy in different hydro-solvers. We also found that for the implementation of the diffusion scheme in the SPH-codes, the existence of a sufficient number of the gas-particles, which is the carrier of the metals, is necessary. So we tested a new initial condition for proper implementation of the diffusion scheme on the SPH simulations. By comparing the metal-contamination of the circumgalactic medium with different hydrodynamics models, we quantify the diffusion strength of AMR codes using diffusion parameterization of the SPH codes and also suggest the calibration solutions in the different behavior of codes in metal-outflow.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
• /
• v.29 no.3
• /
• pp.43-53
• /
• 2023

Background: Patients with neck pain develop instability due to muscle imbalance, decreased proprioception, and balance disorders. Studies have examined various exercise methods as treatment methods, but few studies have compared the effects of cervical stabilization exercise and dynamic balance exercise. The purpose of this study was to investigate the effects of dynamic balance exercise on pain, functional level, and psychosocial level in patients with non-specific chronic neck pain. Methods: Thirty-four non-specific chronic neck pain patients were randomly assigned to the experimental group (EG, n=17) and control group (CG, n=17); the cervical stabilization exercise and dynamic balance exercise program were applied to the EG; and only the cervical stabilization exercise program was applied to the CG. The intervention was conducted twice a week, for six weeks. Assessment items evaluated pain, dysfunction (Korean version neck disability index), range of motion, craniocervical flexion test, cervical deep flexor endurance test, and psychosocial level. Data analysis was performed using intention-to-treat analysis as assigned. To analyze differences in the items assessed in the two groups, we used a repeated measures analysis of variance with an interaction between group (EG, CG) and time point (baseline, 6 weeks, 12 weeks). Results: The endurance of the cervical flexor muscles between the group and the measurement point after intervention (p<.05). Both groups showed significantly improved endurance between time points after the intervention (p<.05), with the EG showing a greater change than the CG. None of the other measurement items differed in the pattern of change between measurement points. Conclusion: In conclusion, the EG applying a cervical stabilization exercise and a dynamic balance exercise experienced a significant difference in muscle endurance improvement compared to the CG. We propose an exercise intervention program that includes stabilization exercises and dynamic balance exercises for patients with chronic cervical pain who lack muscle endurance.

• Journal of the Korean earth science society
• /
• v.40 no.6
• /
• pp.584-598
• /
• 2019

In this study, the effects of air-sea interactions on precipitation over the Seoul-Gyeonggi region of the Korean Peninsula from 28 to 30 August 2018, were analyzed using a Regional atmosphere-ocean Coupled Model (RCM). In the RCM, a WRF (Weather Research Forecasts) was used as the atmosphere model whereas ROMS (Regional Oceanic Modeling System) was used as the ocean model. In a Regional Single atmosphere Model (RSM), only the WRF model was used. In addition, the sea surface temperature data of ECMWF Reanalysis Interim was used as low boundary data. Compared with the observational data, the RCM considering the effect of air-sea interaction represented that the spatial correlations were 0.6 and 0.84, respectively, for the precipitation and the Yellow Sea surface temperature in the Seoul-Gyeonggi area, which was higher than the RSM. whereas the mean bias error (MBE) was -2.32 and -0.62, respectively, which was lower than the RSM. The air-sea interaction effect, analyzed by equivalent potential temperature, SST, dynamic convergence fields, induced the change of SST in the Yellow Sea. In addition, the changed SST caused the difference in thermal instability and kinematic convergence in the lower atmosphere. The thermal instability and convergence over the Seoul-Gyeonggi region induced upward motion, and consequently, the precipitation in the RCM was similar to the spatial distribution of the observed data compared to the precipitation in the RSM. Although various case studies and climatic analyses are needed to clearly understand the effects of complex air-sea interaction, this study results provide evidence for the importance of the air-sea interaction in predicting precipitation in the Seoul-Gyeonggi region.

• Journal of Korean Orthopaedic Sports Medicine
• /
• v.1 no.2
• /
• pp.154-158
• /
• 2002

Purpose: To compare the results of open and arthroscopic method in recurrent anterior should erinstability. Materials and Methods: The 68 patients who have been taken the open or arthroscopic Bankartrepair for the period of Jan. 1995 to April. 2000. One group (23 patients) had elected an arthroscopic Bankart repair, the other group (45 patients) had chosen open stabilization. Patients were followed up12 to 63 months (ave. 34 months) after surgery. Results: We found 2 cases of subluxation out of open repair group, and then treated by conservative method. There were another 2 cases of dislocation and 2 cases of subluxation out of arthroscopicrepair group, and we have taken out 1 case of reoperation by open method. Using the functional scales by Rowe, the patients who have taken the open method posted at the average point of 87, while the arthroscopic method posted 85 points. Patients satisfaction points were 84.6 and 72.5 respectively. There were no criteria of statistically significant except stability and motion score. Conclusion: Open Bankart repair would be better in stability, and arthroscopic method in ROM gain. Proper patient selection based on physical examination and arthroscopic inspection to optimize the indications contributed to successful treatment.