• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.251-259
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• 2023

In the path traveling of differential-drive robots, the steering controller plays an important role in determining the path-following performance. When a robot with a pure-pursuit algorithm is used to continuously drive a right-angled driving path in an unstructured environment without turning in place, the robot cannot accurately follow the right-angled path and stops driving due to the ground and motor load caused by turning. In the case of pure-pursuit, only the current robot position and the steering angle to the current target path point are generated, and the steering component does not reflect the speed plan, which requires improvement for precise path following. In this study, we propose a driving algorithm for differentially driven robots that enables precise path following by planning the driving speed using the radius of curvature and fusing the planned speed with the steering angle of the existing pure-pursuit controller, similar to the Model Predict Control control that reflects speed planning. When speed planning is applied, the robot slows down before entering a right-angle path and returns to the input speed when leaving the right-angle path. The pure-pursuit controller then fuses the steering angle calculated at each path point with the accelerated and decelerated velocity to achieve more precise following of the orthogonal path.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.4
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• pp.601-608
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• 2023

Mobile robots are widely used in industries because mobile robots perform tasks in various environments. In order to carry out tasks, determining the precise location of the robot in real-time is important due to the need for path generation and obstacle detection. In particular, when mobile robots autonomously navigate in indoor environments and carry out assigned tasks within pre-determined areas, highly precise positioning performance is required. However, mobile robots frequently experience data missing in wireless communication environments. The robots need to rely on predictive techniques to autonomously determine the mobile robot positions and continue performing mobile robot tasks. In this paper, we propose an extended Kalman filter-based algorithm to enhance the accuracy of mobile robot localization and address the issue of data missing. Trilateration algorithm relies on measurements taken at that moment, resulting in inaccurate localization performance. In contrast, the proposed algorithm uses residual values of predicted measurements in data missing environments, making precise mobile robot position estimation. We conducted simulations in terms of data missing to verify the superior performance of the proposed algorithm.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.3
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• pp.427-432
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• 2023

In this study, MEC (: Multi-access Edge Computing) proposes a cloud service network configuration for various tests of autonomous vehicles to which V2X (: Vehicle to Everything) is applied in Wave, LTE, and 5G networks and MEC App (: Application) applied V2X service function test verification of two domains (operator (KT, SKT, LG U+), network type (Wave, LTE (including 3G), 5G)) in a specific region. In 4G networks of domestic operators (SKT, KT, LG U+ and Wave), MEC summarized the improvement effects through V2X function blocks and traffic offloading for the purpose of bringing independent network functions. And with a high level of QoS value in the V2X VNF of the 5G network, the traffic steering function scenario was demonstrated on the destination-specific traffic path.

• Industry Promotion Research
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• v.9 no.1
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• pp.47-55
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• 2024

In the transportation sector, reducing total vehicle mileage and passenger vehicle traffic are proposed as strategies to achieve carbon neutrality. To achieve this, MaaS services must be actively promoted with the goal of revitalizing public transportation. In order to promote MaaS, individual movement data is required, such as the individual's means of movement, route, and conversion of the individual's means of use. However, in Korea, there are legal limitations in collecting and utilizing data on individual movements. As the right to request transmission of personal information was newly established in the revised Personal Information Protection Act in 2023, a law was established to collect and utilize data on individual movements. However, enforcement ordinance, detailed rules, instructions, guidelines must be prepared, and the standardization of data format and transmission system for collecting my data needs to take precedence.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.675-680
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• 2010

Background: The aim of this study was to identify the distinguishing clinicoradiologic findings of traumatic tracheobronchial injury. Material and Method: Between January 2003 and December 2009, six patients who underwent surgical repair for traumatic tracheobronchial injury due to blunt trauma were included in this study. We evaluated the mechanism of the injury, the coexisting injuries, the time until the making diagnosis and treatment, the diagnostic methods, the anatomic location of the injury and the surgical outcomes. Result: The mechanisms of injury were traffic accident and crushing forces. The frequent symptoms were subcutaneous emphysema, dyspnea and pain, and the common radiologic findings were pneumothorax, mediastinal emphysema, rib fracture and lung contusion. Only 2 patients were diagnosed by chest CT and the others were not diagnosed preoperatively. The location of injury was the trachea in 2 patients and the bronchial tree in 4 patients. There was no postoperative mortality or anastomotic leak; however, vocal cord palsy occurred in one patient. The most distinguishing sign was persistent lung collapse even though the chest tube was connected with negative pressure. Conclusion: Although it was not easy to diagnose traumatic tracheobronchial injury without a clinical suspicion, the distinguishing clinical symptoms and CT findings could help to make an early diagnosis without performing bronchoscopy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.432-439
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• 2020

Brake judder has been identified in some operating military units of Korean Light Tactical Vehicles(KLTV) with In-board brake systems to improve braking performance. Severe vibration generated while driving the vehicle may reduce the KLTV's driving stability and further lead to accidents. For the prevention of this, this study analyzes the root cause through the failure analysis on the vehicles with the brake judder identified. Furthermore, the improvement factor was derived by identifying a vibration transmission path by analyzing the vibration transmission mechanism. The study analysis confirmed that the vibration of the frame during braking in the tactical vehicle is a cold judder phenomenon, which is caused by an increase in disk thickness variation due to rust and foreign substances under excessive brake disc's run-out. In addition, it was confirmed that such vibration can be reduced by improving the mounting structure. So, an improvement method for each factor was suggested and its effectiveness was verified by comparison test. Finally, it is expected that the improvement plans derived through this study can be used in the development of a next military vehicle.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.3
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• pp.18-31
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• 2018

Since accidents of hazardous material transport vehicle on roadways cause severe damage in the form of disaster, foreign countries have long been engaged in systematic management and establishment of relevant laws and policies for the road safety. Recently, over 10-kilometer long tunnel, such as Inje-Yangyang Tunnel and Geumjeongsan Tunnel, has been opened on the expressway and the production of various hazardous materials is increasing with the development of chemical technology. However, road laws related to the safe operation of hazardous materials transport vehicles are still lacking, and policy measures for managing them have not been specified. It is an important task to recognize the risk of accidents of hazardous material transport vehicles and to secure road safety by establishing a management plan for road managers. Therefore, this study analyzed the feasibility of the traffic regulation of expressway tunnel in South Korea and suggested a direction for management. The results of this study can be utilized as the primary data for the revision of law related to hazardous materials transport vehicles on roadways and the derivation of optimal route of hazardous materials transport vehicles.

• Journal of radiological science and technology
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• v.38 no.3
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• pp.261-266
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• 2015

Intravenous urography (IVU) for urolithiasis is a radiologic examination to diagnosis stone in the ureter path using iodine contrast media, which is radioopacity material. The method includes compression on the upper iliac crest. The compression band prevents outlet of the contrast media through the bladder and enables easier movement to upper urinary tract. This usage depends on the policy of a hospital. Therefore, this study aimed to review and compare the characteristic of progress of contrast media either in compression and non-compression. The retrospective image measurement on 60 cases of intravenous pyelography was conducted at a hospital with the identical type and amount of contrast media as well as criteria for testing. Image measurement was limited to 5 minutes clip, which is optimal for progress of contrast media depending on usage of the compression band. Also, anatomical regions were set as following: "RP" is from renal pyramid to renal pelvis, "PL" is from renal pelvis to lumbar three endplate, and "IU" and "IL" for upper and lower parts from both iliac crests. Analysis has been conducted through the statistical method based on Fisher's Exact Test to find if there are differences of distribution with the anatomical regions with compression or no compression. It has been confirmed that there is no statistical significant difference as the video measurement on 30 cases of compression and non-compression group respectively resulted in P value of 0.580 from left and 0.711 from right (both 0.960). Therefore, it has been concluded that application of a compression band on an intravenous pyelography for urolithiasis patient does not meaningfully affect the progress of contrast media.

• Journal of Korean Society of Transportation
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• v.19 no.3
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• pp.115-131
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• 2001

The Purpose of this study is to develop a simulation model for large-scale network with interrupted flow as well as uninterrupted flow. The Cell Transmission(CT) theory is used to simulate traffic flow. Flow transition rules have been newly developed to simulate traffic flows at merging and diverging sections, and signalized intersections. In the model, it is assumed that dynamic OD table is exogenously given. Simulation results for toy network shows that the model can explain queue dynamics not only in signalized intersections of urban arterials, but also in merging and diverging sections of freeway. In case study, the model successfully simulated traffic flows of 145,000 vehicles on CBD network of city of Seoul with 74 traffic zones, 133 signalized intersections among 395 nodes and 1110 links.

• Clinics in Shoulder and Elbow
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• v.15 no.2
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• pp.109-116
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• 2012

Purpose: The aim of this study was to evaluate preoperative ultrasonographic findings and usefulness in ulnar neuropathy around elbow. Materials and Methods: Twenty-two patients with ulnar neuropathy were performed preoperative ultrasonogram. The route, location, thickness of the ulnar nerve and space occupying lesion through longitudinal scan were evaluated. Cross-sectional areas of the ulnar nerve were measured at the level of medial epicondyle and 3 cm proximal and distal to the medial epicondyle through axial scan. Correlations between swelling ratio of ulnar nerve and eletrophysiologic study and preoperative Dellon's assessment were checked. Results: In 21 cases (95.6%) of total 22 cases, diffuse swelling of the ulnar nerve around elbow were identified. 4 cases had space occupying lesions including 3 ganglionic cysts and 1 heterotopic ossification. Cross sectional areas at the level of medial epicondyle were significantly larger than at the level of 3 cm proximal and distal to the medial epicondyle (p<0.05). There were no statistically significant correlations between swelling ratio of ulnar nerve and eletrophysiologic study and preoperative clinical assessment (p>0.05). Conclusion: This study showed that ultrasonography was helpful to detect etiology of ulnar neuropathy around elbow such as space occupying lesion, morphological change or dislocation of ulnar nerve. It could be useful tool for diagnosis and treatment in patients with ulnar neuropathy at elbow.