• Title/Summary/Keyword: Technology-Engineering

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Solution Based Epoxidation Towards Facilitating the Production of Epoxidized Isoprene Rubbers

  • Zhang, Xiaojie;Sinha, Tridib Kumar;Oh, Jeong Seok;Kim, Jin Kuk
    • Elastomers and Composites
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    • v.55 no.3
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    • pp.199-204
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    • 2020
  • Considering the immense applicability of isoprene rubbers, such as natural rubber (NR) and synthetic polyisoprene rubber (IR), attempts are being made to introduce more functionality within the rubber structure, e.g. epoxidation, to widen their technological viability. Epoxidation introduces polar epoxy bonds into the rubber molecular chain, resulting in enhanced intermolecular interactions among the rubber chains, increasing the oil resistance and air impermeability. Although there have been many reports on the epoxidation of NR in its latex form, there has been no such report using its solid form (or gum), which limits the epoxidation in terms of portability. Furthermore, the gum form has longer lifetime, while the latex form has limited lifetime for its efficient use. In this study, the epoxidation of natural rubber and polyisoprene rubber (using meta-chloroperoxybenzoic acid (mCPBA) as the epoxidizing agent) by dissolving their gum in hexane (i.e., the solution method) have been studied and compared. The effects of the amount of mCPBA, reaction time, and reaction temperature were investigated. The present process is easy and facilitates the epoxidation of rubbers in their solid form; therefore, it can be used for industrial upscaling of epoxidized rubber production.

A Gaussian Approach in Stabilizing Outputs of Electrical Control Systems (전기제어 설비의 출력 안정화를 위한 가우시안 접근법)

  • Basnet, Barun;Bang, Jun-ho;Ryu, In-ho;Kim, Tae-hyeong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.11
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    • pp.1562-1569
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    • 2018
  • Sensor readings always have a certain degree of randomness and fuzziness due to its intrinsic property, other electronic devices in the circuitry, wires and the rapidly changing environment. In an electrical control system, such readings will bring instability in the system and other undesired events especially if the signal hovers around the threshold. This paper proposes a Gaussian-based statistical approach in stabilizing the output through sampling the sensor data and automatic tuning the threshold to the range of multiple standard deviations. It takes advantage of the Central limit theorem and its properties assuming that a large number of sensor data samples will eventually converge to a Gaussian distribution. Experimental results demonstrate the effectiveness of the proposed algorithm in completely stabilizing the outputs over known filtering algorithms like Exponential smoothing and Kalman Filter.

A Tangential Cutting Algorithm for Rapid Prototype System using Genetic Algorithm (유전자 알고리즘을 이용한 쾌속조형 경사절단 알고리즘)

  • Lee, Hyo-Jin;Chun, In-Cook;Kong, Yong-Hae;Kim, Seung-Woo;Joo, Young-Cheol;Um, Tai-Joon;Bang, Jae-Cheol
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.343-346
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    • 2003
  • 기존 쾌속조형시스템의 단점을 보완하기 위해 본 연구팀에서 개발한 쾌속조형시스템을 수직절단에 의해 층별 성형할 경우 가공된 물체의 표면에 계단형 표면과 같은 왜곡현상이 발생한다. 이러한 왜곡 현상을 보완하기 위해 수직절단이 아닌 경사절단하여 계단형 윤곽과 같은 표면 왜곡의 문제점을 보완하고자 한다. 최적의 경사절단선분을 구하기 위해 경사절단선분의 길이와 중간층 점의 거리를 정의하여 이를 최소화하는 에너지 함수를 구현하였다. 에너지를 최소화하기 위한 알고리즘으로 급강하법을 사용하였으나, 이 방법은 에너지가 작아지는 방향으로만 움직이기 때문에 물체의 윤곽이 복잡할 경우 최적이 아닌 다른 위치에 귀착하는 지역적 최적해가 발생한다. 본 논문에서는 이러한 지역적 최적해를 벗어나 최적의 경사절단선분을 찾기 위해 유전자 알고리즘을 사용하였다. 유전자 알고리즘을 사용할 경우, 급강하법에서 발생하였던 지역적 최적해 문제가 해결되어 최적의 위치를 찾을 수 있었다.

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Chip-Interleaved Self-Encoded Multiple Access with Iterative Detection in Fading Channels

  • Kim, Youn-Seok;Jang, Won-Mee;Kong, Yan;Nguyen, Lim
    • Journal of Communications and Networks
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    • v.9 no.1
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    • pp.50-55
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    • 2007
  • We propose to apply chip interleaving and iterative detection to self-encoded multiple access (SEMA) communications. In SEMA, the spreading code is obtained from user bit information itself without using a pseudo noise code generator. The proposed scheme exploits the inherent diversity in self encoded spread spectrum signals. Chip interleaving not only increases the diversity gain, but also enhances the performance of iterative detection. We employ user-mask and interference cancellation to decouple self-encoded multiuser signals. This paper describes the proposed scheme and analyzes its performance. The analytical and simulation results show that the proposed system can achieve a 3 dB power gain and possess a diversity gain that can yield a significant performance improvement in both Rayleigh and multipath fading channels.

Structural and Electrical Properties of Zn-Mn-O System Ceramics for the Application of Temperature Sensors (온도센서로의 응용을 위한 Zn-Mn-O계 세라믹의 구조적, 전기적 특성)

  • Kim, Kyeong-Min;Lee, Sung-Gap;Lee, Dong-Jin;Park, Mi-Ri;Kwon, Min-Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.8
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    • pp.470-475
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    • 2016
  • In this study, $Zn_xMn_{3-x}O_4$ (x=0.95~1.20) specimens were prepared by using a conventional mixed oxide method. All specimens were sintered in air at $1,200^{\circ}C$ for 12 h and cooled at a rate of $2^{\circ}C/min$ to $800^{\circ}C$, subsequently quenching to room temperature. We investigated the structural and electrical properties of $Zn_xMn_{3-x}O_4$ specimens with variation of ZnO amount for the application of NTC thermistors. As results of X-ray diffraction patterns, all specimens showed the formation of a complete solid solution with tetragonal spinel phase. And, the second phase was observed by the solubility limit of Zn ions in $x{\geq}1.10$ composition. The average grain size was increased from $2.72{\mu}m$ to $4.18{\mu}m$ with increasing the compositional ratio of Zn ion from x=0.95 to 1.20, respectively. $Zn_{1.10}Mn_{1.90}O_4$ specimen showed the minimum electrical resistance of $57.5k{\Omega}$ at room temperature and activation energy of 0.392 eV.

A Multi-Group Analysis of Risk Management Practices of Public and Private Commercial Banks

  • REHMAN, Khurram;KHAN, Hadi Hassan;SARWAR, Bilal;MUHAMMAD, Noor;AHMED, Wahab;REHMAN, Zia Ur
    • The Journal of Asian Finance, Economics and Business
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    • v.7 no.11
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    • pp.893-904
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    • 2020
  • The study examines the relationship between credit risk and operational risk (understanding of risk management, risk identification, risk assessment and control, and risk monitoring) on risk management practices followed by private and public sector commercial banks. The cross-sectional data method was used to check the impact of risk management practices. Data was collected from the bank employees and a total of 284 respondents were finally selected for further analysis. Measurement Invariance of Composite Models analysis is used to test the quality of the measurement model for sub-samples, and multi-group analysis is used for path analysis in sub-sample through PLS-SEM. The findings of the study as the total sample show that both types of banks are managing adequate and significant risk management practices. On the other hand, sub-groups' results show private sector banks are more momentous than public sector banks. Risk identification is significantly different at the sub-group level, which shows public sector banks are more concentrating on this type of risk. Understanding of risk management has no significant effect on both types of banks and risk assessment & control for public sector banks, and there is a difference in the risk management practices among private and public sector commercial banks.

A Latent Factor (PLS-SEM) Approach: Assessing the Determinants of Effective Knowledge Transfer

  • ANJUM, Reham;KHAN, Hadi Hassan;BANO, Safia;NAZIR, Sidra;GULRAIZ, Hira;AHMED, Wahab
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.2
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    • pp.851-860
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    • 2021
  • The Knowledge Transfer (KT) for higher education institutions (HEIs) is boundless. Still and all, the members of the staff affiliated with these institutions do recognize an array of hitches in relation to KT practices. The study in question underscores social interactions, training, and Information and Communication Technology (ICT) as the primary barriers and treats them as the independent variables of the study. The study posits that inadequate management of the above-mentioned barriers would impact effective KT unfavorably. Besides, putting forth some striking solutions needed to fix the obstructions that hamper the adequate management of the KT exercises is another aim of the study. For data collection purposes, the study picks out higher education institutions (public) of the Quetta district. The reckoned sample size is 317 subjects. The research type that has been used is cross-sectional research and, in this context, the cross-sectional explanatory sequential design has been used. Concerning the findings of the paper, the results of PLS-SEM show positive and significant relationships of social interaction and training with knowledge transfer, while ICT shows an insignificant positive relationship with the knowledge transfer. The most influencing factor for the knowledge transfer is social interaction as suggested by social interaction theory.

An Instructional Design for the Converged English-Science Teaching Method using PBL Model in Elementary School (PBL 모형을 적용한 초등학교 영어·과학 융합 수업 모델 설계)

  • Park, In-Hwa
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.7
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    • pp.66-72
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    • 2020
  • In order to cultivate talented people with national economic influence in the rapidly changing 21st- century modern society, STEM(Science Technology Engineering Mathematics) education has been emphasized in advanced countries such as America and England. In South Korea, STEAM(Science Technology Engineering Arts Mathematics) education is emphasized by adding Arts. The objective of STEAM education is to strengthen the interest and motivation of learners, to focus on experience, exploration, experimentation, to solve convergent thinking and real-life problems, rather than cramming method of teaching and memorization. This study identifiesan instructional design for converged English, the world's official language, and science which is found in nearly all disciplines. With the development of the 4th industrial revolution based on the PBL model, learners participate in their lessons voluntarily for problem-solving skills. The instructional design based on the ADDIE model consists of 5 procedures: Analysis, Design, Development, Implementation, and Evaluation. The goal of fostering talented people with national economic influence is also important, and the teacher in education must recognize the importance of STEAM education and an appropriate instructional design should be studied constantly.

Statistical Optimization of Medium Components for Milk-Clotting Enzyme Production by Bacillus amyloliquefaciens D4 Using Wheat Bran-an Agro-Industry Waste

  • Zhang, Weibing;He, Xiaoling;Liu, Hongna;Guo, Huiyuan;Ren, Fazheng;Gao, Weidong;Wen, Pengcheng
    • Journal of Microbiology and Biotechnology
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    • v.23 no.8
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    • pp.1084-1091
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    • 2013
  • In this paper, two statistical methods were applied to optimize medium components to improve the production of the milk-clotting enzyme by Bacillus amyloliquefaciens D4. First, wheat bran juice, skim milk powder, and $Na_2HPO_4$ were shown to have significant effects on D4 enzyme production using the Plackett-Burman experimental design. Subsequently, an optimal medium was obtained using the Box-Behnken method, which consisted of 3.31 g/l of skim milk powder, 5.0 g/l of sucrose, 0.1 g/l of $FeSO_4{\cdot}7H_2O$, 0.1 g/l of $MgSO_4{\cdot}7H_2O$, 0.1 g/l of $MnSO_4{\cdot}2H_2O$, 0.1 g/l of $ZnSO_4{\cdot}7H_2O$, 1.52 g/l of $Na_2HPO_4$, and 172.45 g/l of wheat bran juice. With this optimal medium, the milk-clotting enzyme production was remarkably enhanced. The milk-clotting enzyme activity reached 3,326.7 SU/ml after incubation of 48 h, which was 1.76-fold higher than that of the basic medium, showing that the Plackett-Burman design and Box-Behnken response surface method are effective to optimize medium components, and B. amyloliquefaciens D4 possessed a high rennet-producing capacity in the optimal medium.

Design and Implementation of User Feedback Block Editor for Dynamic E-Book (동적 전자책을 위한 블록 조립식 사용자 피드백 에디터 설계 및 구현)

  • Choi, Ja-Ryoung;Yun, Jihyun;Jang, Miyeon;Jang, Suji;Lim, Soon-Bim
    • Journal of Digital Contents Society
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    • v.18 no.1
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    • pp.63-70
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    • 2017
  • Recently, as user feedback such as social reading become active, demand has been increased on e-book contents making which is based on user feedback. However, to reflect the user feedback onto the e-book, direct coding is required, which was difficult to the author who was not good at programming. To resolve this problem, Block assembly style feedback editor system, using Blockly was developed. This editor enables to reflect the user feedback by area allocation, component allocation, block editing, and code generating insertion, contrary to the existing way of programming realization in which direct coding was required for input, processing and output separately. This system was developed by using HTML. Javascript, PHP, and Codeigniter. Block editing is enabled to do provision and assembly of blocks by Blockly. The function of code generation & insertion allows to insert the Library function code. Through this system, the general users who are not capable of coding also can reflect feedback without doing actual coding.