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Partial strengthening method for cold stamped B-pillar with minimal shape change
No full textThe partial strengthening method for pre-stamped panels both avoids excessive strength enhancement over the entire product and substantially reduces the processing cost compared to conventional hot press forming. In this paper, we propose two types of partial strengthening processes to selectively increase the local strength of a cold stamped B-pillar by utilizing an induction coil system and water spray quenching to induce the martensitic transformation in the target region. Thermo-mechanical FE analyses were conducted to evaluate the effect of the process parameters such as the quenching rate, quenching time, and heating width on the shape changes during the partial strengthening processes while simultaneously considering the thermal dilatation and transformation plasticity.This work was financially supported by the "Forming analysis of center pillar stiffener with partial strengthening techniques" program of the Production Development Division Department, HYUNDAI Motors Group, and "Human Resources Program in Energy Technology" program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) under the Ministry of Trade, Industry and Energy, Republic of Korea (no. 20174010201310)
Image Processing Algorithm for Real-Time Crack Inspection in Hole Expansion Test
No full textThis paper mainly focuses on development of the smart crack inspection algorithm facilitating the through-thickness crack during the hole expansion test, which makes it possible to calculate the hole expansion ratio, automatically, with the image processing technique. The proposed crack inspection algorithm consists of six steps such as binarization, blob detection, background deletion, ROI selection, image linearization, and crack identification using the C# language. This algorithm is able to capture the various types of the through-thickness and double cracks irrespective of the reflectance and the initial thickness of the applied sheet materials. In addition, it is possible to keep trace of the in-plane crack and its propagation during the HER test.Author Prof. Jonghun Yoon has received a research funding from the National Research Foundation of Korea (NRF) Grant funded by the Korea government (2016R1C1B1006875), and the "Human Resource Program in Energy Technology" of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted by the Ministry of Trade, Industry & Energy (20174010201310). The authors declare that they have no conflict of interest
Low-Cost Dual-Mechanical-Port Dual-Excitation Machine for Washing Machine Application
No full textThis paper proposes a low-cost dual-mechanical-port dual-excitation machine for washing machine application. The proposed machine artfully combines two machines (vernier and permanent magnet synchronous machine (PMSM)). An outer vernier rotor is used for the low-speed washing operations, and an inner PMSM rotor is used for the high-speed drying operations of the washing machine. The proposed machine is compared with a similar recently presented machine to verify its cost-effectiveness. Comparison using the finite element analysis (FEA) shows that the ferrite magnets used in the proposed topology are more cost-effective. Furthermore, compared to the existing machine, the power factor of the proposed machine is high during the drying operation; hence, a lower rating inverter is sufficient to drive the machine, which further reduces the overall cost. In addition, the proposed machine provides similar efficiencies as the existing machine for both washing and drying operations.This work was supported in part by the BK21PLUS Program through the National Research Foundation of Korea within the Ministry of Education, and in part by the National Research Foundation of Korea (NRF) grant funded by the Korean Government, Ministry of Science, under Grant NRF-2017R1A2B4007697
Dynamic Pricing in a Multi-Period Newsvendor Under Stochastic Price-Dependent Demand
No full textThe faster growth of technology stipulates the rapid development of new products; with the spread of new technologies old ones are outdated and their market demand declines sharply. The combined impact of demand uncertainty and short life-cycles complicate ordering and pricing decision of retailers that leads to a decrease in the profit. This study deals with the joint inventory and dynamic pricing policy for such products considering stochastic price-dependent demand. The aim is to develop a discount policy that enables the retailer to order more at the start of the selling season thus increase the profit and market share of the retailer. A multi-period newsvendor model is developed under the distribution-free approach and the optimal stocking quantities, unit selling price, and the discount percentage are obtained. The results show that the proposed discount policy increases the expected profit of the system. Additionally, the stocking quantity and the unit selling price also increases in the proposed discount policy. The robustness of the proposed model is illustrated with numerical examples and sensitivity analysis. Managerial insights are given to extract significant insights for the newsvendor model with discount policy
Determination of the Gait Stability of the Lower-Limb Exoskeleton Robot Through the Stability Circle
No full textPatients with complete paralysis that only walk with the assistance of exoskeleton robots because they lost their ability to walk. However, robots do not allow the exoskeleton robot to grasp the current state before walking and change the walking pattern. A 'Stability Circle Region' was proposed to determine the current state of the exoskeleton robot. The Stability Circle is an area that can determine the possibility of a fall situation before the next walk using the link parameters of the robot and the current center of gravity of the patients. This study verified the validity of 'stability circle' by simulating the change in the center of mass. Simulation results can be used to determine the stability of walking depending on whether the position of the center of mass before the walking is included in the circle area
An Efficient Indoor Target Tracking Algorithm Using TDOA Measurements With Applications to Ultra-Wideband Systems
No full textThe ultra-wideband technique has shown its effectiveness for indoor target tracking. Various types of measurements have been applied to ultra-wideband systems for indoor target tracking, and the time difference of arrival (TDOA) measurement-based approaches are the most widely used methods due to their good accuracy and feasibility. Target tracking with the IDOA measurements usually encounters the problem of correlated measurement noises, as one sensor network utilizes the common reference sensor for measurement generation. The off-diagonal entries in the measurement error covariance matrix become non-zero values, which makes the standard target tracking algorithms inconvenient for practical installation of an ultra-wideband system. Another problem in sensor networks is properly exploiting the measurements obtained from multiple sensors considering practical conditions, such as storage limitations or computational resource consumption. The parallel update and the serial update are usually applied for the multi-sensor tracking problem. This paper presents a target tracking algorithm that integrates the Cholesky decomposition to decorrelate the measurement noises for the serial update, thus improving computational efficiency. The proposed algorithm is realized in an ultra-wideband system for real-time target tracking, and an experiment using real data is conducted to validate its practicability.This work was supported by the Institute for Information and Communications Technology Promotion (IITP) grant funded by the Korean Government (MSIP) under Grant 2016-0-00191
An Extensive Approach to Features Detection and Description for 2-D Range Data Using Active B-splines
No full textThis letter presents three novel contributions for the two-dimensional laser scan data. First, a low-level point feature detector for stable interest point detection. Second, an approach for high-level B-splines features extraction, and finally, a local descriptor for the interest points based on the shape context representation of the uniformly distributed points on the B-splines features. The clues of stable interest points obtained from the detector are used in the B-splines features extraction from the scan data, which enables lightweight and accurate mapping of the environment using fewer control points instead of scan data points. This letter also proposes benchmark metrics to evaluate the performance of the extracted high-level features approach in comparison with the state-of-the-art methodology. A robust descriptor for the interest points offers an efficient association and correspondence matching. Consistent results compared with the state-of-the-art FALKO-BSC and FLIRT-β-Grid features in experiments with standard datasets prove the stability of our proposed interest point detector and the proficiency of the descriptor. The results of efficient localization using the pair are also presented
Compact Implementation and Analysis of Rainbow on 8bits-Microcontroller Uunit
No full text본 논문에 이차식 기반 서명인 Rainbow를 8비트 MCU(Microcontroller Unit)에 적용하기 위해 최적화 하는 방안을 검토하고 구현한다. 양자 컴퓨터가 개발되면서 기존의 암호 알고리즘 특히, 서명 기법의 보안성을 위협함에 따라 IoT 기기에도 양자내성을 갖춘 서명 기법을 적용해야할 필요성이 있다. 현재 제안된 양자내성암호는 격자 기반, 해쉬 기반, 코드 기반 그리고 다변수 이차식 기반 암호 알고리즘 및 서명 기법들이 있는데, 특히 다변수 이차식 서명기법은 기존의 서명 기법과 비교해 속도가 빨라 IoT 기기에 적합하다. 그러나 키의 길이가 크고 연산이 많아 IoT 기기 중 메모리와 성능에 큰 제약이 있는 8비트 MCU에는 기존의 구조 그대로 구현하기 어려워 이에 적합한 최적화가 필요하다. 따라서 본 논문에서는 다변수 이차식 서명 기법인 Rainbow를 8비트 MCU에 키를 나누어 저장하는 방안과 연산방식을 최적화하여 메모리 소모가 적고 연산 속도가 빠르게 알고리즘을 개선하고, 구현해본 후 각 최적화 방식에 따른 성능을 비교한다.
In this paper, we propose and implement a method to optimize Rainbow for 8 bit MCU(Microcontroller Unit). As quantum computers have been developed, the security of existing cryptography, especially the signature algorithms, has been threatened, so it is necessary to apply a signature scheme with a quantum-resistance to IoT devices. Currently, the proposed PQC(Post Quantum Cryptography) are lattice-based, hash-based, code-based, and MQ(Multivariate Quadratic)-based cryptographic algorithms and signature schemes. In particular, MQ-based signature schemes are faster than conventional signature schemes and are suitable for IoT devices Do. However, it is difficult to apply 8-bit MCU, which has a large key length and large number of computations, to the memory and performance of IoT devices. In this paper, we propose a method of storing Rainbow, which is a MQ-based signing scheme, in 8-bit MCU by dividing the key and optimizing the computation method. By reducing the memory consumption and improving the algorithm speedily, Compare performance
Design of Novel High Performance Dual Rotor Flux-Switching Drum Winding Machine
No full textThis paper proposes a novel high performance dual rotor flux-switching drum winding (DRFS-DW) machine. To achieve high torque density, the machine adopted the dual rotor topology to utilize two airgaps boosting torque, and drum winding to maximize the flux linkage. Performance of the drum winding in dual rotor machine was compared with conventional concentrated winding to show its superiority. For better description of high torque density of DRFS-DW machine, flux linkage difference of two different winding configuration for proposed machine was shown with the aid of magnetic equivalent circuit (MEC) and finite element method (FEM) analysis. Drum winding showed higher flux linkage difference, hence higher torque in same driving condition. The DRFS-DW machine was optimized for higher torque density and lower torque ripple. The optimized model was finally compared with conventional FSPMM and initial model to show the improved performance.This work was supported in part by the Human Resources Program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20154030200730)
Content Analysis of Linguistic Characteristics of Foreign Language Use in Korean Magazine Advertising
No full textBackground/Objectives: The purpose of this study is to examine the linguistic and expressive characteristics used in Korean magazine advertisements.
Methods/Statistical analysis: Use of foreign language is an important trend in advertising content. Relatively few studies have analyzed foreign language in advertising content. This study reviewed the content of Korean magazine advertising from 1995 to 2015 using the content analysis method.
Findings: The present article found that the number of Korean magazine advertisements with a foreign language was not significantly different longitudinally from the 1990s to the 2010s. The results of the three research questions showed that there was not a significant change in the usage of foreign languages in the studied years. However, the results of this study showed that there was a significant difference in the advertising appeal of using foreign languages in general women’s magazines. The results also showed that Korean magazine advertising used foreign language in anappropriate way, which implies that using foreign language is more effective than using domestic language for informing and persuading consumers in a market.
Improvements/Applications: The findings of the study provide a unique view of the field to researchers and advertisers, including directions for future research and practical implications for advertising creative research