Free-Positioning Wireless Power Transfer Using a 3D Transmitting Coil for Portable Devices

Nam Ha-Van,Hoang Le-Huu,Minh Thuy Le,Kwangsuk Park,Chulhun Seo 한국전자파학회JEES 2020 Journal of Electromagnetic Engineering and Science Vol.20 No.4

The free-positioning wireless power transfer (WPT) system has drawn attention in recent years. Traditionally, a WPT system can transfer energy in one or two directions on the same plane, but it leads the restrictions of angle and axis misalignment between a transmitter and a receiver coil. In this paper, we propose a free-positioning WPT system using a three-dimensional cubic-shaped transmitting coil for portable device charging. A small receiving coil is placed inside the transmitter to achieve the transferred energy through the magnetic resonant coupling. In addition, the equivalent circuit and the mutual inductance between the Tx and Rx coils are analyzed. Finally, a practical experiment is implemented to verify the transfer performance, which can reach up to about 50% power transfer efficiency. The proposed system can charge in spatial freedom.

Analytical and Experimental Investigations of Omnidirectional Wireless Power Transfer Using a Cubic Transmitter

Ha-Van, Nam,Seo, Chulhun Institute of Electrical and Electronics Engineers 2018 IEEE transactions on industrial electronics Vol.65 No.2

<P>In recent years, wireless power technology has been promoted for recharging systems for portable devices that are used in everyday life. The conventional technology used for this purpose, which is based on magnetically coupled resonators, has provided promising results but is limited in range and direction at the receiving terminal. In this paper, we propose an omnidirectional wireless power transfer (WPT) system with a novel cubic transmitter to achieve relatively high efficiency. Specifically, a single power source is utilized to drive the current of the transmitter without phase and current control methodology. Energy delivery is transmitted to the receiver through magnetic resonant coupling in the medium-range WPT mode. In addition, an equivalent circuit model of a coupling two-coil system is derived and mathematically analyzed. The efficiency of the proposed omnidirectional WPT system depending on the various distances between the transmitter and the receiver, as well as the transmitter structure, is evaluated via analysis and implementation. Finally, practical experimental results from the resonant coupling system confirm the theoretical analysis of the cubic transmitter and the omnidirectional power transfer capability, which demonstrate approximately 60% power transfer efficiency.</P>

A Single-Feeding Port HF-UHF Dual-Band RFID Tag Antenna

Nam Ha-Van,Chulhun Seo 한국전자파학회JEES 2017 Journal of Electromagnetic Engineering and Science Vol.17 No.4

In this paper, a dual-band high frequency (HF) and ultra-high frequency (UHF) radio-frequency identification (RFID) tag antenna is presented that operates in the 13.56 MHz band as well as in the 920 MHz band. A spiral coil along the edges of the antenna substrate is designed to handle the HF band, and a novel meander open complementary split ring resonator (MOCSRR) dipole antenna is utilized to generate the UHF band. The dual-band antenna is supported by a single-feeding port for mono-chip RFID applications. The antenna is fabricated using an FR4 substrate to verify theoretical and simulation designs, and it has compact dimensions of 80 mm × 40 mm × 0.8 mm. The proposed antenna also has an omnidirectional characteristic with a gain of approximately 1 dBi.

SSR Mapping of Genes Conditioning Soybean Resistance to Six Isolates of Xanthomonas axonopodis pv. glycines

Van, Kyujung,Ha, Bo-Keun,Kim, Moon Young,Moon, Joong Kyung,Paek, Nam-Chon,Heu, Sunggi,Lee, Suk-Ha 한국유전학회 2004 Genes & Genomics Vol.26 No.1

Bacterial leaf pustule (BLP), caused by xanthomonas axonopodis pv. glycines, is one of the most prevalent bacterial diseases in plants. Qualtitative trait loci (QTLs) for resistance to BLP in soybean (Clycine max [Glycine max [L.] Merr.) were identified using simple sequence repeat (SSR) markers, and the consistency of QTL detection across bacterial isolates as well as across greenhouse and field experiments was examined. Recombinant inbred lines (RILs) derived from a cross of BLP-susceptible 'Suwon157' and BLP-resistant 'Danbaekkong' were utilized to identify QTLs conditioning resistance to BLP with 76 SSR markers. For phenotypic analysis, six isolates of X. axonopodis were collected from different geographical locations. A combination of single-factor analysis of variance and multiple regression analysis revealed that three QTLs conditioned resistance to BLP in the field.. Under greenhouse conditions, one to four QULs were revealed to be associated with resistance to each isolate. Satt372 on linkage group (LG) D2 was associated with resistance to all six isolates under greenhouse and field conditions, indicating that resistance to BLP was mainly controlled by a single major gene tightly linked to Satt372. Several minor QTLs of LG A1, C1, F, L, and O were also found to condition resistance to various isolates.

Photodiode-Based Chua's Circuit with Light Controllability

Nam, Sang Guk,Nguyen, Van Ha,Song, Hanjung Science Press 2014 CHINESE PHYSICS LETTERS Vol.31 No.6

<P>We present a photodiode-based Chua's chaotic circuit that is controllable by light. The proposed circuit consists of an inductor, two passive capacitors, a photodiode-based variable resistor, and a positive feedback transconductor with negative nonlinearity. The chaotic dynamics of the circuit were verified by using the simulation program with integrated circuit emphasis analysis using the 0.35μm complementary metal-oxide-semiconductor process parameters. The gain results (such as the time waveform, frequency analysis, three-dimensional attractor, bifurcation and Lyapunov exponents diagrams) confirm that the chaotic behavior of the circuit could be controlled by light intensity via the photodiode-based variable resistor.</P>

The Impact of Service Recovery on Satisfaction and Word of Mouth of International Tourists Towards Homestays: An Empirical Study in Vietnam

Van Nam MAI,Quoc Nghi NGUYEN,Du Ha Long NGUYEN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.8

Service failures are fairly common these days, and recovering from them is difficult. If service failures are not addressed quickly, the service provider may lose revenue and customers. A good service recovery strategy will positively impact the business results of the service provider. The study aims to demonstrate the impact of service recovery on the satisfaction and word of mouth of international visitors towards homestays in the Mekong Delta, Vietnam. The research data was collected from 320 international visitors who have used services at homestays and experienced service failures in the Mekong Delta, Vietnam. Structural equation modeling was applied to analyze the data. The result shows that 3 dimensions constitute service recovery which are distributive justice, interactional justice, and procedural justice. Most importantly, the study has proved the positive impact of service recovery on both satisfaction and word of mouth of overseas tourists towards homestays in the Mekong Delta, Vietnam. The results have stressed the importance of service recovery to tourists’ perceptions of service quality and service image. In addition to this, the study suggests that homestay owners should develop risk handling and risk prevention plans for their services.

Ultra-broadband and flexible metamaterial absorber based on MoS2 cuboids with Mie resonances

Ha Duong Thi,Nam Man Hoai,Tung Bui Son,Khuyen Bui Xuan,Lam Vu Dinh,Le-Van Quynh 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.11

In this work, we present a type of fexible and broadband metamaterial absorber operating in the GHz range. The proposed structure consists of three layers: a periodic square-shaped array made of molybdenum disulfde (MoS2) on the top, a continuous polyimide layer in the middle and a continuous copper layer at the bottom. For fat model, the proposed absorber exhibits a broadband absorption in the frequency range of 10.1–17.6 GHz with an absorption of more than 90% under normal incidence. Due to the symmetry of structure, the absorption feature is polarization-insensitive. The absorption remains above 80% in the frequency range of 11.1–15.6 GHz when the incident angle is up to 60° for TE-polarized wave, while the absorption is higher than 90% in the frequency range of 13.5–18 GHz for incident angles up to 60° for TM-polarized wave. For bending model, the absorption is signifcantly expanded when the bending radius decreases to under 100 mm. The physical mechanism of the absorption properties is explained in detail by the electric feld distribution, the magnetic feld distribution following the Mie resonance theory and infuence of the loss of MoS2. Obtained results in the work might contribute to the development of potential applications based on metamaterials in the microwave region such as imaging, protecting and light emitting devices.

Bioinformatic identification and expression analysis of the chicken B cell lymphoma (BCL) gene

Van Thai Than,Ha Thi Thanh Tran,Duc Viet Ly,Hoang Vu Dang,Minh Nam Nguyen,Anh Duc Truong 한국유전학회 2019 Genes & Genomics Vol.41 No.10

Background B cell lymphoma (BCL) families play an important role in apoptosis as a growth factor, cell death programming, cytokine expression and immune-related genes expression. Objectives In this study, to investigate the roles of BCLs, we performed genome-wide identification, expression and functional analyses of the BCL family in chicken. Methods Chicken BCLs genes were identified and analyzed by using bioinformatics approach. Expression profiles and Hierarchical cluster analysis of the BCLs genes in different chicken tissues were obtained from the genome-wide RNA-seq in the GEO, and Cluster and Java Treeview, respectively. Results A total of 16 BCLs genes were identified from the chicken genome, which could be further classified into five distinct groups in the phylogenetic tree. On the other hand, the interaction among BCLs proteins and between BCLs proteins with NF-κB subunits are limited, indicating that the remaining the functions of BCLs protein could be investigated in chicken. Moreover, KEGG pathway analysis indicated that BCL gene family was involved in regulation of apoptotic and immune response. Finally, BCL gene family was differentially expressed in chicken tissues, pathogen infection and growth stages of early chicken early embryo. Conclusion This study provides significant insights into the potential functions of BCLs in chicken, including the regulation of apoptosis, cell death and expression of immune-related genes.

Multiplex PCR Strategy for Rapid Identification of Viral Honeybee Disease in Korea

Ha Na Jung,Mi Sun Yoo,Young Ha Kim,Nam Hee Kim,Kondreddy Eswar Reddy,Dong Van Quyen,Suk Chan Jung,Seung Won Kang 대한수의학회 2014 대한수의학회 학술대회발표집 Vol.2014 No.-

Effects of seasonal variations on sediment-plume streaks from dredging operations

Kim, Nam-Hoon,Pham, Van Sy,Hwang, Jin Hwan,Won, Nam Il,Ha, Ho Kyung,Im, Jungho,Kim, Youngsung Elsevier 2018 MARINE POLLUTION BULLETIN Vol.129 No.1

<P><B>Abstract</B></P> <P>When mixtures of aggregates and water dredged from the seabed are discharged at the surface into the adjacent water from a barge, coarse sediments sink immediately and fine sediments are suspended forming a plume. Recently, elongated plumes of fine sediment were observed by satellites near a dredging location on the continental shelf. Such plume streaks were longer in certain conditions with seasonality than expected or reported previously. Therefore, the present work studied the appearance of sediment plume with field measurements and numerical simulations and explains the seasonally varying restoring force and thicknesses of the surface mixed layer resulting from the vertical density distribution near the surface, along with mixing by hydrodynamic process. The resulting mixtures, after vertical restoring and mixing with the surroundings, determine the horizontal transport of suspended sediments. A numerical model successfully reproduced and explained the results from field measurements and satellite images along with the seasonal variations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Image captured by a satellite reported the unexpectedly long streaks of sediment plume from a dredging site. </LI> <LI> Elongations of plume depend on the seasonal variations of density differences between the mixtures and surface waters. </LI> <LI> While a long streak is observed, restoring force is too weak to sink the mixtures of sediment and water to the bottom. </LI> <LI> Seasonal variations of the surface mixed layer thickness significantly affect the development of the elongated plumes. </LI> </UL> </P>