• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1999-2004
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• 2009

Since 2003, the domestic ground signalling system of the Kyeongbu and Honam lines has been steadily improving with the introduction of the ATP system and application of the system to the train is actively being pursued for 2009 target. Therefore, new ground signalling systems are being installed to the trains and track conditions to control the train speed to a maximum of either 80km/h, 120km/h, 150km/h, or 160km/h. As well, considering safe breaking distance, block signalling has been installed and also the change over times of the track switching device has been adjusted according to the train speed. Since the new Tilting trains will be running faster than present trains, at speeds over 180 km/h, we anticipate that there will be problems with present signalling facilities. Therefore this paper attempts to examine the various problems with the interface between the ATP signalling system and the new Tilting trains and also it will propose the most effective operating plan based upon case studies of successful foreign operations.

• 한국의학물리학회지:의학물리
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• 제24권4호
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• pp.230-236
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• 2013

Our purpose is to present a novel technique for delivering craniospinal irradiation in the supine position using a perfect match, field-in-field (FIF) intrafractional feathering, and simple forward-optimization technique. To achieve this purpose, computed tomography simulation was performed with patients in the supine position. Half-beam, blocked, opposed, lateral, cranial fields with a collimator rotation were matched to the divergence of the superior border of an upper-spinal field. Fixed field parameters were used, and the isocenter of the upper-spinal field was placed at the same source-to-axis distance (SAD), 20 cm inferior to the cranial isocenter. For a lower-spinal field, the isocenter was placed 40 cm inferior to the cranial isocenter at a constant SAD. Both gantry and couch rotations for the lower-spinal field were used to achieve perfect divergence match with the inferior border of the upper-spinal field. A FIF technique was used to feather the craniospinal and spinal-spinal junction daily by varying the match line over 2 cm. The dose throughout the target volume was modulated using the FIF simple forward optimization technique to obtain homogenous coverage. Daily, image-guided therapy was used to assure and verify the setup. This supine-position, perfect match craniospinal irradiation technique with FIF intrafractional feathering and dose modulation provides a simple and safe way to deliver treatment while minimizing dose inhomogeneity.

• 한국컴퓨터정보학회논문지
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• 제23권2호
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• pp.45-51
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• 2018

In this paper, we propose a Designed and Developed home router management system. Through the fourth industrial revolution and development of IoT technology, now people can experience a wide range of IoT related services at their workplace or daily lives. At the industrial site, IoT devices are used to improve productivity such as factory automation, and at home, IoT technology is used to control home appliances from a remote distance. Usually IoT device is integrated and controlled by the router. Home router connects different IoT devices together at home, however when security issues arise, it can invade personal privacy. Even though these threats exist, the perception for home router security is still insufficient. In this paper, we have designed and developed home router management system using DEVS methodology to promote the safe use of home router. Through the DEVS methodology, we have designed the system and developed the mobile application. This management system enables users to set up security options for home router easily.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1290-1303
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• 2005

In this research, a remote control system has been developed and implemented, which combines autonomous obstacle avoidance in real-time with force-reflective tele-operation. A tele-operated mobile robot is controlled by a local two-degrees-of-freedom force-reflective joystick that a human operator holds while he is monitoring the screen. In the system, the force-reflective joystick transforms the relation between a mobile robot and the environment to the operator as a virtual force which is generated in the form of a new collision vector and reflected to the operator. This reflected force makes the tele-operation of a mobile robot safe from collision in an uncertain and obstacle-cluttered remote environment. A mobile robot controlled by a local operator usually takes pictures of remote environments and sends the images back to the operator over the Internet. Because of limitations of communication bandwidth and the narrow view-angles of the camera, the operator cannot observe shadow regions and curved spaces frequently. To overcome this problem, a new form of virtual force is generated along the collision vector according to both distance and approaching velocity between an obstacle and the mobile robot, which is obtained from ultrasonic sensors. This virtual force is transferred back to the two-degrees-of-freedom master joystick over the Internet to enable a human operator to feel the geometrical relation between the mobile robot and the obstacle. It is demonstrated by experiments that this haptic reflection improves the performance of a tele-operated mobile robot significantly.

• Journal of Korean Neurosurgical Society
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• 제61권6호
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• pp.731-736
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• 2018

Objective : Ultrasonography (US) is the most non-invasive, safe, and, especially in the period of infancy, best method for visualizing and examining the spinal cord. Furthermore, US is the primary work-up for development of the spinal canal, and for follow-up on issues relating to subcutaneous tissues, bone development, and the spinal cord. Conus medullaris terminates at the second lumbar vertebra, according to a consensus in the literature. Methods : Healthy children under the age of 6 months who were admitted to the radiology clinic for routine USG follow-ups between the dates of March 2012 to December 2014 were included in this study. Results : Our study includes data from 1125 lumbosacral ultrasounds. The terminal point of the conus level of the attended infants, superior, middle part, inferior of the vertebrae L1, L2, and L3. Furthermore, the termination of the discal distance ratio did not differ significantly between genders. Conclusion : Therefore, according to our results, gender is not an influencing factor in the termination of the spinal cord. Based on the study we performed, as well as the previous literature, in infants without a recognized spinal pathology, the spinal cord is detected below the vertebra L3.

• 한국해양공학회지
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• 제30권5호
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• pp.426-430
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• 2016

Recently, many unmanned surface vehicles (USVs) have been developed and researched for various fields such as the military, environment, and robotics. In order to perform purpose specific tasks, common autonomous navigation technologies are needed. Obstacle avoidance is important for safe autonomous navigation. This paper describes a vector field histogram+ (VFH+) based obstacle avoidance method that uses the monocular vision of an unmanned surface vehicle. After creating a polar histogram using VFH+, an open space without the histogram is selected in the moving direction. Instead of distance sensor data, monocular vision data are used for make the polar histogram, which includes obstacle information. An object on the water is recognized as an obstacle because this method is for USV. The results of a simulation with sea images showed that we can verify a change in the moving direction according to the position of objects.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.167-178
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• 2021

This study aims to identify the influence of paradoxical leadership on proactive work behavior mediated through psychological safety in the hotel industry. This study employs survey data of five-star deluxe hotels in South Korea using convenience sampling. The number of 270 cases was used for analysis and the hypotheses were analyzed with structural equation modeling and AMOS 20. Paradoxical leadership includes five sub-variables of self-centeredness with other-centeredness (SO) distance and closeness (DC), uniformly and individualization (UI), work requirements and flexibility (RF), and decision control and autonomy (CA). The results indicate that DC, UI, and CA positively influence psychological safety. Further, RF and CA make a positive impact on proactive work. Psychological safety fully mediates the effect of DC and UI on proactive work behavior and partially mediates the effect of CA on it. The findings of this study suggest that the impact of paradoxical leadership on proactive work behavior can be strengthened when this relationship is accompanied with psychological safety and other mediation variables for the relationship need to be further investigated. This study suggests how hotel managers enhance the level of proactive work behavior by training themselves to be paradoxical leaders and making psychologically safe environment.

• Geomechanics and Engineering
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• 제18권2호
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• pp.215-224
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• 2019

Excavation of long tunnels by shielded TBMs is a safe, fast, and efficient method of tunneling that mitigates many risks related to ground conditions. However, long-distance tunneling in great depth through adverse geological conditions brings about limitations in the application of TBMs. Among various harsh geological conditions, squeezing ground as a consequence of tunnel wall and face convergence could lead to cluttered blocking, shield jamming and in some cases failure in the support system. These issues or a combination of them could seriously hinder the performance of TBMs. The technique of excavation has a strong influence on the tunnel response when it is excavated under squeezing conditions. The Golab water conveyance tunnel was excavated by a double-shield TBM. This tunnel passes mainly through metamorphic weak rocks with up to 650 m overburden. These metamorphic rocks (Shales, Slates, Phyllites and Schists) together with some fault zones are incapable of sustaining high tangential stresses. Prediction of the convergence, estimation of the creeping effects and presenting strategies to overcome the squeezing ground are regarded as challenging tasks for the tunneling engineer. In this paper, the squeezing potential of the rock mass is investigated in specific regions by dint of numerical and analytical methods. Subsequently, several operational solutions which were conducted to counteract the challenges are explained in detail.

• 대한건축학회논문집:계획계
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• 제35권9호
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• pp.41-48
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• 2019

Recently as the rapid increasing of the elderly, silver housing has grown up. Though much fire evacuation and safety law, fire accident is most dangerous problem in our society. So this study is the purpose to analyze evacuation safety in urban silver housing of floor planning by corridor types using human behavior simulation. The methodology of this study is 'Literature Review' and 'Simulation'. This study has been carried out on silver housing's definition, types, fire safety theory and relation law. To proof evacuation safety, this study measured escaping time, longest distance, and bottleneck counting using human behavior simulation. This study use game engine simulation program to analyze 6 corridor types experimental model. As the result of simulation, this study compare between ASET and simulation result. The result come down to 3 part. First, double loaded corridor type is the most dangerous on urban silver housing. Second, Safe shelter's location and number cause increasing of escaping time. Lastly escaping time is influenced by behavior of agent, bottle neck strike frequency.

• 한국의학물리학회지:의학물리
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• 제32권4호
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• pp.122-129
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• 2021

Purpose: This study aimed to design a multipurpose dose verification phantom for external audits to secure safe and optimal radiation therapy. Methods: In this study, we used International Atomic Energy Agency (IAEA) LiF powder thermoluminescence dosimeter (TLD), which is generally used in the therapeutic radiation dose assurance project. The newly designed multipurpose phantom (MPP) consists of a container filled with water, a TLD holder, and two water-pressing covers. The size of the phantom was designed to be sufficient (30×30×30 cm³). The water container was filled with water and pressed with the cover for normal incidence to be fixed. The surface of the MPP was devised to maintain the same distance from the source at all times, even in the case of oblique incidence regardless of the water level. The MPP was irradiated with 6, 10, and 15 MV photon beams from Varian Linear Accelerator and measured by a 1.25 cm³ ionization chamber to get the correction factors. Monte Carlo (MC) simulation was also used to compare the measurements. Results: The result obtained by MC had a relatively high uncertainty of 1% at the dosimetry point, but it showed a correction factor value of 1.3% at the 5 cm point. The energy dependence was large at 6 MV and small at 15 MV. Various dosimetric parameters for external audits can be performed within an hour. Conclusions: The results allow an objective comparison of the quality assurance (QA) of individual hospitals. Therefore, this can be employed for external audits or QA systems in radiation therapy institutions.