• Journal of Power Electronics
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• 제18권1호
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• pp.23-33
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• 2018

Silicon Carbide (SiC) MOSFET belongs to the family of wide-band gap devices with inherit property of low switching and conduction losses. The stable operation of SiC MOSFET at higher operating temperatures has invoked the interest of researchers in terms of its application to high power density (HPD) power converters. This paper presents a performance study of SiC MOSFET based two-phase interleaved boost converter (IBC) for regulation of avionics bus voltage in more electric aircraft (MEA). A 450W HPD, IBC has been developed for study, which delivers 28V output voltage when supplied by 24V battery. A gate driver design for SiC MOSFET is presented which ensures the operation of converter at 250kHz switching frequency, reduces the miller current and gate signal ringing. The peak current mode control (PCMC) has been employed for load voltage regulation. The efficiency of SiC MOSFET based IBC converter is compared against Si counterpart. Experimentally obtained efficiency results are presented to show that SiC MOSFET is the device of choice under a heavy load and high switching frequency operation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• 제57권4호
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• pp.356-361
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• 2008

The conventional drive system of SRM has a current sensor per each phase. The torque demand signal generated by the outer control loop is translated into individual current reference signal for each phase. The torque is controlled by regulating these currents. Using the SRM in a variable-speed control, the phase currents are generally regulated to achieve a square wave. The simplest form of current regulation uses fixed frequency delta modulation of the phase voltages. The aim of this paper is to regulate 3-phases current of SRM by only single current sensor using delta modulation with digital chip. In this paper, the asymmetric bridge converter which is able to control independently phases and be excited simultaneously is used as the driver system for 6/4 poles SRM. And the current sensor is replaced 3 sensors of each phase with only one on bus line of converter so as to detect current of every phase. The proposed delta modulation technique has been implemented in a simple digital logic circuit using EPLD(Electrically Programmable Logic Device). This method is verified through simulation and experiment results.

• Archives of Plastic Surgery
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• 제34권4호
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• pp.535-537
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• 2007

Purpose: We experienced a patient with posttraumatic duplication of the sternoclavicular joint causing a protruding deformity, whose major complaint was aesthetic. The patients history, radiologic findings, and surgical treatment are reported. Methods: A 41-year-old bus driver complained a bony prominence at the left medial clavicle, which had developed after a fracture. The patient was annoyed by the protrusion, which was even visible, when he was wearing a pullover. A three dimensional CT scan showed that the medial head was split into two portions, of which the anterior portion was protruding. In general anesthesia the anterior portion of the medial head was excised. Results: The bony prominence was corrected successfully. Follow up three dimensional CT scans showed that the anterior cortex of the clavicle had regenerated completely at the resection line one year after the operation. Conclusion: Surgical interventions for complications after clavicular fracture are usually carried out, only if there is a limitation of function or if it is painful. We report of a patient with posttraumatic bifurcation of the medial clavicular head, most probably caused by malunion. Upon the patient's request, the deformity causing protrusion of the medial clavicular area was successfully resected for cosmetic reasons.

• The Journal of the Korea institute of electronic communication sciences
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• 제11권5호
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• pp.531-538
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• 2016

Driving behaviors such as speeding and illegal u-turn which violate traffic rules are main causes of car accidents, and they can lead to serious accidents. Bus drivers are less aware of dangers of illegal u-turn, and infrastructures such as traffic enforcement equipment and watchmen are deficient. This research aims to develop technology for estimating driving behaviors based on map-matching in order to prevent illegal u-turns. For this research, 23,782 of u-turn permit data and 146,000 of speed limit data are collected nationwide, and an estimation algorithm is built with these data. Then, an application based on android is developed, and finally, tests are conducted to assess the accuracy in data computations and GPS data map-matching, and to extrapolate driving behavior. As a result of the tests, the accuracy results in the map-matching is 86% and the assessment of driving behavior is 83%, while the display of the data output yielded 100% accuracy. Additional research should focus on improvement in accuracy through the development of a robust monitoring system, and study of service scenarios for technology application.

• Journal of Korean Society of Transportation
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• 제17권4호
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• pp.85-97
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• 1999

The Purpose of this Paper is the development of the day-to-day dynamic combined model on the evaluation of traveller's traffic information for multi-mode and multi-class environments. Information is assumed to be provided for multi-mode such as bus and automobile. and multi-class such as a driver with and without route guidance equipment when they depart for their trips. The information provision strategies have been developed in the base of user equilibrium, system optimum and in between them. The Sioux Falls network is used for the evaluation of the model and information provision strategies. In the numerical analysis, a Braess' paradox for the information provision, which is the increase of travel time even though the number of information usage level and user are increased, has been occurred so that these kinds of information strategies should be implemented with special care.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제28권2D호
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• pp.191-203
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• 2008

According to a characteristic analysis of traffic accidents of industrial vehicles (RTSA 2007), the occurrence rate and lethality per 10,000 vehicles is 6.7 times higher and 5.3 times higher than that of non-industrial vehicles respectively. For the recent 10 years, in contrast to the 1.5% decrease of the annual rate of entire traffic accidents, the accident rate of industrial vehicles have been increasing 2.0% on the annual average. For the recent 10 years, the accidents of a freight truck and bus have been steadily falling off. But, in the case of a taxi, it has constantly been rising 5.6%. In these situations, the countermeasures to decrease the accident rate are suggested by grasping the inclination of taxi drivers through Q analysis which is character and psychology analysis method.

• Annals of Occupational and Environmental Medicine
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• 제35권
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• pp.52.1-52.13
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• 2023

Background: In 2019, the International Agency for Research on Cancer re-evaluated the carcinogenicity of night-shift work and reported that there is limited evidence that night-shift work is carcinogenic for the development of prostate cancer. Therefore, in 2020 and 2021, the Korean Epidemiologic Investigation Evaluation Committee concluded that 2 cases of prostate cancer were occupational diseases related to the night-shift work. Here, we report the 2 cases of prostate cancer in night-shift workers which were first concluded as occupational diseases by the Korean Epidemiologic Investigation Evaluation Committee. Case presentation: Patient A: A 61-year-old man worked as a city bus driver for approximately 17 years, from 2002 to 2019, and was exposed to night-shift work during this period. In March 2017, the patient was diagnosed with high-grade prostate cancer through core-needle biopsy after experiencing stinging pain lasting for 2 months. Patient B: A 56-year-old man worked as an electrician and an automated equipment operator in a cement manufacturing plant for 35 years from 1976 to 2013 and was exposed to night-shift work during this period. In 2013, the patient was diagnosed with high-grade prostate cancer through core needle biopsy at a university hospital because of dysuria that lasted for 6 months. Conclusions: The 2 workers were diagnosed with high-grade prostate cancer after working night shifts for 17 and 35 years respectively. Additionally, previous studies have reported that high-grade prostate cancer has a stronger relationship with night-shift work than low or medium-grade prostate cancer. Therefore, the Korean Epidemiologic Investigation Evaluation Committee concluded that night-shift work in these 2 patients contributed to the development of their prostate cancer.