• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.127-134
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• 2021

This study presents an overhang-type rail traction system using dual brushless AC (BLAC) motors with hall sensors. For an accurate position and moving length control of the designed rail traction system, instantaneous position controller using speed reference model and modified disturbance observer for BLAC motor with hall sensor are proposed. The presented speed reference model is designed to satisfy the required performance of 200 mm/s with proper acceleration and deceleration slopes to reduce mechanical vibration. Through the instantaneous speed reference model, instantaneous position and speed errors can be compensated together. Furthermore, the modified disturbance observer for BLAC motors with low-resolution hall sensors can improve the torque and speed control performance. The proposed disturbance observer is based on an actual motor speed. However, the feedback speed information of the hall sensor is not enough for use in the low-speed region. The practical adopted disturbance observer uses an activation speed band to the actual torque controller of the designed rail traction system. The proposed position control scheme is verified by the MATLAB-Simulink model and a practical manufactured traction system. In the computer simulation and experiments, the proposed position control scheme shows advanced control performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.738-740
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• 2016

오늘날 테마파크는 다양한 테마 적 요소들을 적용한 다양한 신기술로 무장되어있다. 사람들은 복잡한 현실 세계를 떠나 일탈을 꿈꾸며 재미와 감동, 스릴에 목마르다. 현실 세계에서는 느낄 수 없는 판타스틱한 재미와 경험은 현실 세계의 고달픔을 잠시나마 잊고 싶은 사람들의 발걸음을 테마파크로 이끌어 온다. 테마파크는 또 다른 세상(Another World)으로 사람들을 초대하는 현실 속 가상의 공간이다. 테마파크는 언제든지 찾아와 재미있는 경험을 해보고 몇 번을 찾아와도 지루하지 않은 누구나 꼭 한번 가보고 싶어 하는 매력적인 장소이다. 기존의 테마파크는 이러한 소비자의 니즈를 충족하기 위해 새롭고 신선하며 유희적인 테마를 적용한 파크를 끊임없이 개발하고 발전시켜야 한다. 본 논문은 테마파크 어트랙션발전에 유용한 장점을 가지고 있는 가상현실을 테마파크에 적용하는 방법을 제안한다.

• Journal of Ocean Engineering and Technology
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• v.29 no.1
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• pp.45-55
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• 2015

Because of the high stress concentration near the toe of a welded joint, the calculation of local stress using the finite element method which is relevant to the fatigue strength of the weld toe crack, is a challenging task. This is mainly caused by the sensitivity of finite element analysis, which usually occurs near the area of a dramatically changing stress field. This paper presents a novel numerical method through which a less mesh-sensitive local stress calculation can be achieved based on the 3D solid finite element, strictly sticking to the original definition of hot spot stress. In order to achieve the goal, a traction stress, defined at 0.5t and 1.5t away from the weld toe, was calculated using either a force-equivalent or work-equivalent approach, both of which are based on the internal nodal forces on the imaginary cut planes. In the force-equivalent approach, the traction stress on the imaginary cut plane was calculated using the simple force and moment equilibrium, whereas the equivalence of the work done by both the nodal forces and linearized traction stress was employed in the work-equivalent approach. In order to confirm the validity of the proposed method, five typical welded joints widely used in ships and offshore structures were analyzed using five different solid element types and four different mesh sizes. Finally, the performance of the proposed method was compared with that of the traditionally used surface stress extrapolation method. It turned out that the sensitivity of the hot spot stress for the analyzed typical welded joints obtained from the proposed method outperformed the traditional extrapolation method by far.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.401-407
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• 2014

In this paper, the effect of cohesive laws on the finite element analysis of crack propagation using cohesive elements is investigated through three-point bending and double cantilever beam problems. The cohesive elements are implemented into ABAQUS/Standard user subroutines(UEL), and the shape of cohesive law is varied by changing parameters in polynomial functions of cohesive traction-separation relations. In particular, crack propagation behaviors are studied by comparing load-displacement curves of the analysis models which have different shapes of cohesive laws with the same values of fracture energy and cohesive strength. Furthermore, the influence of the element size on crack propagation is discussed in this study.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.393-399
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• 2013

In this paper, a novel approach to estimate cohesive laws for the mode I fracture of the graphene is presented by combining molecular dynamic simulations and an inverse algorithm based on field projection method and finite element method. The determination of crack-tip cohesive laws of the graphene based on continuum mechanics is a non-trivial inverse problem of finding unknown tractions and separations from atomic simulations. The displacements of molecular dynamic simulations in a region far away from the crack tip are transferred to finite element nodes by using moving least square approximation. Inverse analyses for extracting unknown cohesive tractions and separation behind the crack tip can be carried out by using conservation nature of the interaction J- and M-integrals with numerical auxiliary fields which are generated by systematically imposing uniform surface tractions element-by-element along the crack surfaces in finite element models. The preset method can be a very successful approach to extract crack-tip cohesive laws from molecular dynamic simulations as a scale bridging method.

• Journal of the Korea Convergence Society
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• v.7 no.1
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• pp.25-30
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• 2016

Virtual reality items are increased take-all type of markets like Universal, such as the United States as a leader in the virtual reality technology. Multi-user have to get direct experiences with the whole body like visual, tactile, hearing, sense of movement, and it must be developed new forms of content platform to enjoy immerse deeply into the content. Visitors are not to enjoy the content passively but rather to enjoy the content actively. So it like that should develope content to maximize the immersion. It need the development of new forms of mixed 5D virtual reality Attraction content with all of factors like $360^{\circ}$ circle vision, stereoscopic images, interaction, simulator, and the environmental effect. We proposes how to make the color and brightness calibration technology for this purpose.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.37-43
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• 2023

This study concluded that smart glass can combine realistic media and reasonable technologies to compensate for the disappointment of simple one-dimensional board game contents, suggest various games to board game contents that were only possible through advertisements and promotions, and can promote board games, tourism services, and insufficient tourism contents. Content development is highly complete as an educational content in that it can be omitted or repeated by customers, and it is expected to be a board game using interesting smart glasses for the MZ generation.

• The Journal of the Convergence on Culture Technology
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• v.8 no.4
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• pp.423-428
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• 2022

This paper deals with whether it is possible to find a way to solve the conflict between villagers and tourists by newly defining the difference between free village and public tourist destinations in Korea, reinforce the insufficient guidance and notification services with realistic media, and implement additional killing contents and attractions. Location-based service enables real-time docent service and emergency response and smart glass thread.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.569-573
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• 2018

Music is composed of the sound of many instruments. Among them, the sound of the human voice naturally stands out to us and immediately connects with the listener. However, A lot of different steps go into perfectly mixing a vocal, but I'm going to focus on the most important step, equalization. In this paper, starting with the concept and the type of EQ for the requirements associated with the EQ's work and will know about when and how to use subtractive EQ, additive EQ during the recording and mixing process. EQ is one if the most important tools for mixing, especially when dealing with vocals. The control that EQ's offer allows you work, boosting and cutting to fit the vocal perfectly into the mix. The key to get a professional sounding vocal every time is to always keep in mind what you're trying to achieve stylistically and for it, using reference track is very effective. In addition to EQing, there are a variety of complex working steps such as compression, reverb, chorus, delay, adjusted for the effects of the work and harmonies of backing vocals and that are also very important task. The work of EQing is the beginning of the mixing process, among other things, need to be a detailed work throughout the consideration of the above points to its importance is greater relationship.

• Journal of Internet of Things and Convergence
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• v.8 no.6
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• pp.55-63
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• 2022

In recent years, with the rapid development of large and medium-sized urban rail transit in China, the total operating mileage of high-speed railway and the total number of EMUs(Electric Multiple Units) are rising. The system complexity of high-speed EMU is constantly increasing, which puts forward higher requirements for the safety of equipment and the efficiency of maintenance.At present, the maintenance mode of high-speed EMU in China still adopts the post maintenance method based on planned maintenance and fault maintenance, which leads to insufficient or excessive maintenance, reduces the efficiency of equipment fault handling, and increases the maintenance cost. Based on the intelligent operation and maintenance technology of PHM(prognostics and health management). This thesis builds an integrated PHM platform of "vehicle system-communication system-ground system" by integrating multi-source heterogeneous data of different scenarios of high-speed EMU, and combines the equipment fault mechanism with artificial intelligence algorithms to build a fault prediction model for traction motors of high-speed EMU.Reliable fault prediction and accurate maintenance shall be carried out in advance to ensure safe and efficient operation of high-speed EMU.