• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1903-1908
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• 2008

This paper presents a characteristics of linear induction motor considering airgap variation for railway transit in order to achieve high performance of the vehicle. The operating principle of a LIM(Linear induction motor) is identical to a rotary induction motor. Space-time variant magnetic fields are generated by the primary part across the airgap and induce the electro-motive force(EMF) in the secondary part, a conducting sheet. This EMF generates the eddy currents, which interact with the airgap flux and so produce the thrust force known as Loren's force. Even though the operating principal is exactly same as a rotary motor, the linear motor has a finite length of the primary or secondary parts and it causes static and dynamic end-effect which is the discontinuous airgap flux phenomenon. This end-effect causes the deterioration of the system performance, especially in high-speed operation. Another problem is that construction tolerance restricts the minimum airgap in order to prevent a collision between the primary part and the secondary reaction plate. More over, as the airgap length is getting smaller, the attraction force between the primary part and secondary parts is getting larger dramatically and the attraction force would be another friction against propulsion. Therefore, it is necessary to figure out the characteristics of linear induction motor considering airgap variation in order to achieve high performance of the vehicle. The dynamic model of LIM taking into account end-effects is derived. Then the modified mechanical load equation considering the effect of the attraction and thrust force according to the airgap variation is analyzed. The simulation results are presented to show the effect of the LIM according to the airgap variation.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.10
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• pp.1443-1449
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• 2013

Automatic detection of vehicles in front is an integral component of many advanced driver-assistance system, such as collision mitigation, automatic cruise control, and automatic head-lamp dimming. Regardless day and night, tail-lights play an important role in vehicle detecting and status recognizing of driving in front. However, some drivers do not know the status of the tail-lights of vehicles. Thus, it is required for drivers to inform status of tail-lights automatically. In this paper, a recognition method of status of tail-lights based on video processing and recognition technology is proposed. Background estimation, optical flow and Euclidean distance is used to detect vehicles entering tollgate. Then saliency map is used to detect tail-lights and recognize their status in the Lab color coordinates. As results of experiments of using tollgate videos, it is shown that the proposed method can be used to inform status of tail-lights.

• Journal of the Korea Society of Computer and Information
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• v.26 no.10
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• pp.45-51
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• 2021

In this paper, we propose a 3D design method of the vacuum forming method of the front part to improve the lightness and production efficiency of agricultural electric vehicles. For agricultural electric vehicles, lightness and production efficiency are more important than the strength of materials for collision protection. In this paper, we propose a vacuum forming design method that can replace complex machining processes such as laser machining, bending, and painting. The main purpose of this research is to improve product stability, productivity and convenience through 3D design of the front part and development of vacuum forming mold technology. Research procedure follows the 3D modeling of the front part using CATIA, finite element analysis for the structural stability using ABAQUS, manufacturing prototype for the investigation of the dimensions using 3D scanner and actual driving test under agricultural electric vehicle usage environment. The results verifies the proposed 3D design method of the vacuum forming method and are expected to be widely used by agricultural workers through the simplification of the production process of agricultural electric vehicles.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.1
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• pp.160-173
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• 2021

Recently, research on the development of autonomous vehicles has increased worldwide. Moreover, a means to identify and analyze the characteristics of traffic accidents of autonomous vehicles is needed. Accordingly, traffic accident data of autonomous vehicles are being collected in California, USA. This research examined the characteristics of traffic accidents of autonomous vehicles. Primarily, traffic accident data for autonomous vehicles were analyzed, and the text data used text-embedding techniques to derive major keywords and four topics. The methodology of this study is expected to be used in the analysis of traffic accidents in autonomous vehicles.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.63-73
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• 2021

This paper presents a algorithm for automatic target recognition robust to the influence of the flame in order to track the target by EOTS(Electro-Optical Targeting System) equipped on UAV(Unmanned Aerial Vehicle) when there is aerial target or marine target with flame at the same time. The proposed method converts infrared images of targets and flames into a gradient vector field, and applies each gradient magnitude to a polynomial curve fitting technique to extract polynomial coefficients, and learns them in a shallow neural network model to automatically recognize targets and flames. The performance of the proposed technique was confirmed by utilizing the various infrared image database of the target and flame. Using this algorithm, it can be applied to areas where collision avoidance, forest fire detection, automatic detection and recognition of targets in the air and sea during automatic flight of unmanned aircraft.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.2
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• pp.79-84
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• 2021

The most important device of the AGV is the guide sensor, and the typical function of this sensor is high accuracy and extraction of the road. If the accuracy of the guide sensor is low or the sensor device is extracted the wrong track, this causes the problems such as the AGV collision, track-out, the load falling due to AGV swing. In order to improve these problems, this study is proposed a signal processing method of the guide sensor based on multi-maskings and the center of gravity method, and evaluated its performance. As a result, the proposed method showed that the mean error of absolute value is 2.32[mm] and it showed performance improvement of 27[%] than the center of gravity method of existence. Therefore, when the proposed signal processing method is applied, It is thought that the posture control and driving stability of the AGV will be improved.

• The Journal of Korean Medicine
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• v.42 no.1
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• pp.26-45
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• 2021

Objectives: The purpose of this study was to investigate characteristics of patients who were admitted to an oriental medicine hospital by traffic accident. Methods: The medical charts of 346 patients admitted to an oriental medicine hospital from June 1, 2017 to May 31, 2018 were analyzed. The Numbering Rating Scale (NRS) and duration of hospitalization were used to evaluate characteristics of the patients. Results: Acupuncture, Moxibustion, Infralux were used to treat all the patients. The most frequently used herbal medication was Danggwisu-san(22.25%). 87 patients(25.14%) visited the outpatient department after being discharged from the hospital. The most frequent complaint in terms of pain was cervical pain(82.7%) and of systemic symptom was headache(23.7%). Men and younger aged patients showed higher therapeutic effect than women and older ages. The most common duration of hospitalization was 2~4 days(42.73%) and positively correlated with therapeutic effect. The most frequent interval between time of injury and visit to the hospital was from 0-1 days(68.90%) and showed no relationship with therapeutic effect. The most frequent admission pathway was "Directly to the hospital"(57.51%). Admission pathway was proportionally associated with duration of hospitalization and treatment results were not. The most common vehicle type involved in the traffic accidents was a sedan(72.25%), accident type was a rear-end collision(43.64%) and showed no relationship with therapeutic effect. Conclusions: In this study, therapeutic effects were highly correlated among men, younger ages, and duration of hospital stay, and was not for interval days, admission pathway, vehicle type, and accident type.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.3
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• pp.170-184
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• 2024

With the advancement of autonomous navigation technology in maritime domain, there is an active research on swarming Unmanned Surface Vehicles (USVs) that can fulfill missions with low cost and high efficiency. In this study, we propose a formation control algorithm that maintains a certain shape when multiple unmanned surface vehicles operate in a swarm. In the case of swarming, individual USVs need to be able to accurately follow the target state and avoid collisions with obstacles or other vessels in the swarm. In order to generate guidance commands for swarm formation control, the potential field method has been a major focus of swarm control research, but the method using the potential field only uses the position information of obstacles or other ships, so it cannot effectively respond to moving targets and obstacles. In situations such as the formation change of a swarm of ships, the formation control is performed in a dense environment, so the position and velocity information of the target and nearby obstacles must be considered to effectively change the formation. In order to overcome these limitations, this paper applies a method that considers relative velocity to the potential field-based guidance law to improve target following and collision avoidance performance. Considering the relative velocity of the moving target, the potential field for nearby obstacles is newly defined by utilizing the concept of Velocity Obstacle (VO), and the effectiveness and efficiency of the proposed method is verified through swarm control simulation, and swarm control experiments using a small scaled unmanned surface vehicle platform.

• Journal of Trauma and Injury
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• v.37 no.1
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• pp.67-73
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• 2024

Purpose: Posttraumatic stress disorder (PTSD) is prevalent and is associated with protracted recovery and worse outcomes after injury. This study compared PTSD prevalence using the PTSD Checklist for DSM-5 (PCL-5) with the prevalence of PTSD risk using the Injured Trauma Survivor Screen (ITSS). Methods: Adult trauma patients at a level I trauma center were screened with the PCL-5 (sample 1) at follow-up visits or using the ITSS as inpatients (sample 2). Results: Sample 1 (n=285) had significantly fewer patients with gunshot wounds than sample 2 (n=45) (8.1% vs. 22.2%, P=0.003), nonsignificantly fewer patients with a fall from a height (17.2% vs. 28.9%, P=0.06), and similar numbers of patients with motor vehicle collision (40.7% vs. 37.8%, P=0.07). Screening was performed at a mean of 154 days following injury for sample 1 versus 7.1 days in sample 2. The mean age of the patients in sample 1 was 45.4 years, and the mean age of those in sample 2 was 46.1 years. The two samples had similar proportions of female patients (38.2% vs. 40.0%, P=0.80). The positive screening rate was 18.9% in sample 1 and 40.0% in sample 2 (P=0.001). For specific mechanisms, the positive rates were as follows: motor vehicle collisions, 17.2% in sample 1 and 17.6% in sample 2 (P>0.999); fall from height, 12.2% in sample 1 and 30.8% in sample 2 (P=0.20); and gunshot wounds, 39.1% in sample 1 and 80.0% in sample 2 (P=0.06). Conclusions: The ITSS was obtained earlier than PCL-5 and may identify PTSD in more orthopedic trauma patients. Differences in the frequency of PTSD may also be related to the screening tool itself, or underlying patient risk factors, such as mechanism of injury, or mental or social health.

• Archives of Craniofacial Surgery
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• v.17 no.1
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• pp.28-30
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• 2016

Major maxillofacial bone injury itself can be life threatening from both cardiovascular point of view, as well as airway obstruction. Significant hemorrhage from facial fracture is an uncommon occurrence, and there is little in the literature to guide the management of these patients. We report a 73-year-old male driver who was transported to our hospital after a motor vehicle collision. The patient was hypotensive and tachycardic at presentation and required active fluid resuscitation and transfusion. The patient was intubated to protect the airway. All external attempts to control the bleeding, from packing to fracture reduction, were unsuccessful. Emergency angiogram revealed the bleeding to originate from terminal branches of the sphenopalatine artery, which were embolized. This was associated with cessation of bleeding and stabilization of vital signs. Despite the age and severity of injury, the patient recovered well and was discharged home at 3 months with full employment. In facial trauma patients with intractable bleeding, transcatheter arterial embolization should be considered early in the course of management to decrease mortality rate.