• Journal of Power Electronics
• /
• 제14권4호
• /
• pp.649-660
• /
• 2014

A novel non-isolated bidirectional soft-switching SEPIC/ZETA converter with reduced ripple currents is proposed and characterized in this study. Two auxiliary switches and an inductor are added to the original bidirectional SEPIC/ZETA components to form a new direct power delivery path between input and output. The proposed converter can be operated in the forward SEPIC and reverse ZETA modes with reduced ripple currents and increased voltage gains attributed to the optimized selection of duty ratios. All switches in the proposed converter can be operated at zero-current-switching turn-on and/or turn-off through soft current commutation. Therefore, the switching and conduction losses of the proposed converter are considerably reduced compared with those of conventional bidirectional SEPIC/ZETA converters. The operation principles and characteristics of the proposed converter are analyzed in detail and verified by the simulation and experimental results.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.173-174
• /
• 2006

X-ray analysis on iron ores and reduced iron powders revealed that the main acid-insoluble substances were hexagonal and tetragonal quartz, another substances were sillimanite, alumina-silicate, an unnamed zeolite, all contained Si and Al. Their particle size was in the range of $3{\sim}7\;{\mu}m$. Statistics analysis showed that the AIC for high-grade magnetite powder was $(0.130{\pm}0.010)%$) during the latest five months. The predicting value for reduced iron powder should be 0.179%. However, the testing value for reduced iron powder was $(0.192{\pm}0.014)%$. The limited difference of 0.013% might imply rare pollution coming from the reduction and milling processes. The most important step for control AIC should be the separation process of iron ore powders.

• Structural Engineering and Mechanics
• /
• 제69권1호
• /
• pp.105-120
• /
• 2019

In this paper, a new efficient method for structural modal reanalysis is proposed, which can handle large finite element (FE) models requiring frequent design modifications. The global FE model is divided into a residual part not to be modified and a target part to be modified. Then, an automated matrix permutation and substructuring algorithm is applied to these parts independently. The reduced model for the residual part is calculated and saved in the initial analysis, and the target part is reduced repeatedly, whenever design modifications occur. Then, the reduced model for the target part is assembled with that of the residual part already saved; thus, the final reduced model corresponding to the new design is obtained easily and rapidly. Here, the formulation of the proposed method is derived in detail, and its computational efficiency and reanalysis ability are demonstrated through several engineering problems, including a topological modification.

• 한국산업정보학회논문지
• /
• 제27권2호
• /
• pp.45-51
• /
• 2022

본 논문에서는 장애인들을 위한 단축 입력시스템을 이용하여 기존의 한글, 영문, 숫자 및 기타 특수문자를 입력하고, 입력된 내용을 점자로 변환하는 시스템을 구현하였다. 단축 입력시스템은 5개의 숫자와 4개의 특수 기능키를 사용하여 복잡한 입력 방법 대신 장애인들이 간단하게 입력하도록 설계하였다. 또한, 핸드폰을 사용하여 입력할 수 있도록 앱을 개발하여 중증장애우들이 핸드폰을 사용하여 문자를 입력할 수 있도록 아두이노와 LCD Matrix를 활용하여 시스템을 구현하였다.

• 충청수학회지
• /
• 제35권3호
• /
• pp.205-225
• /
• 2022

In this paper, we derive analytical closed results for the first (a, b)-KA index, the Sombor index, the modified Sombor index, the first reduced (a, b)-KA index, the reduced Sombor index, the reduced modified Sombor index, the second reduced (a, b)-KA index and the mean Sombor index mSO_α for the OTIS biswapped networks by considering basis graphs as path, wheel graph, complete bipartite graph and r-regular graphs. Network theory plays a significant role in electronic and electrical engineering, such as signal processing, networking, communication theory, and so on. A topological index (TI) is a real number associated with graph networks that correlates chemical networks with a variety of physical and chemical properties as well as chemical reactivity. The Optical Transpose Interconnection System (OTIS) network has recently received increased interest due to its potential uses in parallel and distributed systems.

• Advances in aircraft and spacecraft science
• /
• 제9권5호
• /
• pp.433-447
• /
• 2022

This work deals with an explicit guidance and control architecture for autonomous lunar ascent and orbit injection, i.e., the locally-flat near-optimal guidance, accompanied by nonlinear reduced-attitude control. This is a new explicit guidance scheme, based on the local projection of the position and velocity variables, in conjunction with the real-time solution of the associated minimum-time problem. A recently-introduced quaternion-based reduced-attitude control algorithm, which enjoys quasi-global stability properties, is employed to drive the longitudinal axis of the ascent vehicle toward the desired direction. Actuation, based on thrust vectoring, is modeled as well. Extensive Monte Carlo simulations prove the effectiveness of the guidance, control, and actuation architecture proposed in this study for precise lunar orbit insertion, in the presence of nonnominal flight conditions.

• 국제학술발표논문집
• /
• The 6th International Conference on Construction Engineering and Project Management
• /
• pp.708-709
• /
• 2015

In Korea, a series of noise-reduced aluminum forms are being recently used in apartment housing construction. However, their complicated and time-consuming work processes, and the noise which is still generated due to the inherent property of aluminum when especially installing and dismantling them are have been pointed out as a problem to be certainly solved for increasing their practical use in construction sites. The primary objectives of this study are to propose a conceptual design of a newly designed noise-reduced aluminum form in which the noise can be enormously decreased during form works. The conceptual design in this study improved problems of conventional system aluminum forms, and, later, a system aluminum form developed based on this conceptual design will be able to ensure noise-reduction and safety as well as excellent applicability.

• East Asian mathematical journal
• /
• 제21권2호
• /
• pp.151-161
• /
• 2005

We analyze the structure of $C^*-algebras$ generated by left regular isometric representations of semigroups.

• Bulletin of the Korean Chemical Society
• /
• 제24권9호
• /
• pp.1351-1353
• /
• 2003

• 호남수학학술지
• /
• 제24권1호
• /
• pp.103-108
• /
• 2002

Applications of a column-reduced orthogonal rational matrix function to McMillan degrees and Wiener-Hopf factorizations are considered.