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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.
Nam Hoang NGUYEN,Minh Ngoc NGO 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.8
ASEAN Economic Community (AEC) was established in 2015 from 10 countries to realize the ultimate (adopted in 1997), which aimed to transform ASEAN into a stable, prosperous, and highly competitive region with equitable economic development, reduced poverty, and socioeconomic disparities. The purpose of this paper is to examine the effect of knowledge level on the AEC of Vietnamese small and medium enterprises (SMEs) in the textile and apparel industry towards attitudes, readiness, and performance. This study uses convenience sampling to get questionnaires from 150 SMEs in Hanoi, Vietnam. Then, the paper applies SPSS-AMOS 24 to process data. The empirical results show that AEC’s implementation only has a small impact on improving SME performance. However, SMEs have adequate knowledge, attitude, and readiness about AEC. The structural modeling findings indicate that the knowledge factor has an indirect effect on SMEs’ performance. This finding is to provide new insight into the roles of attitude and readiness in the case of Vietnam. These factors are needed to mediate the effect of attitudes and readiness in the relationship between knowledge and business performance, a framework strategy of business organizations, and can be used as a conceptual model to improve SMEs’ performance.
Battery-less Pork Freshness Monitoring Based on High-Efficiency RF Energy Harvesting
( Nam Hoang Nguyen ),( Minh Binh Lam ),( Wan-young Chung ) 한국센서학회 2020 센서학회지 Vol.29 No.5
Food safety has emerged as a growing concern for human health in recent times. Consuming contaminated food may lead to serious health problems, and therefore, a system for monitoring food freshness that is both non-detrimental to the quality of food and highly accurate is required to ensure that only high-quality fresh food packages are provided to the customers. This paper proposes a method to monitor and detect food quality using a compact smart sensor tag. The smart tag is composed of three ultra-low-power sensors, which monitor four major indicators of food freshness: temperature, humidity, and the concentrations of ammonia and hydrogen sulfide gases. An RF energy scavenging circuit is integrated into the smart sensor tag to harvest energy from radio waves at a high frequency of 13.56 MHz to supply sufficient power to the tag. Experimental results show that the proposed energy harvester can efficiently obtain energy at a distance of approximately 40 cm from a 4W reader. In addition, the proposed smart sensor tag can operate without any battery, thereby eliminating the requirement of frequent battery replacement and consequently decreasing the cost. Meanwhile, the freshness of preserved pork is continuously monitored under two conditions-room temperature and refrigerator temperature--both of which are the most common temperatures under which food is generally stored. The food-monitoring experiments are conducted over a period of one week using the proposed battery-less tag. Based on the experimental results, the food assessment is classified into four categories: fresh, normal, low, and spoiled.
Hoang Van Luong,Nguyen Van Long,Vu Binh Duong,Nguyen Linh Toan,Nguyen Van Minh,Le Bach Quang,Nam Hyuck Kim,Sang Yo Byun 한국생물공학회 2009 KSBB Journal Vol.24 No.2
This study was initiated to investigate the impacts of media types and other components on the callogenensis and cell mass production of Panax vietnamensis in the first step of the cell biomass procedure. Four media were checked: Murashige-Skoog (MS), White, Gamborg and Nitch-All. All the four media were shown potential media for Panax vietnamensis callogenensis and cell mass production, in which the MS medium showed the best results: the successful callogenensis ratio and cell mass formation were 30% and 62,93 ± 3,63 mg (DW) respectively, the Nitch medium showed the lowest results: the successful callogenensis ratio and cell mass formation were 15% and 27,10 ± 2,24 mg (DW) respectively. The results showed that the MS medium is the most suitable medium for Panax vietnamensis callogenensis and cell mass production.
La Nam Phat,Tran Quoc Thang,Huynh Cam Nguyen,Dang Thi My Duyen,Dao Xuan Tien,Bui Dang Dang Khoa,Pham Tan Khang,Nguyen Thi Huong Giang,Hoang Minh Nam,Mai Thanh Phong,Nguyen Huu Hieu 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.11
Recycling biomass to cellulose aerogel (Cell-A) provides a promising approach to develop adsorbent materials for spilled-oil recovery. In this work, Cell-A was fabricated from Vietnamese water hyacinth via crosslinking methods using PVA as a crosslinker and freeze-drying process. Various cellulose to PVA ratios were investigated to obtain the optimal synthesis condition. The Cell-A was additionally modified by dip-coating in poly(dimethylsiloxane) (PDMS) and pyrolyzing to form PDMS-coated cellulose aerogels (Cell-AP) and carbon aerogels (CA), respectively. Results of the oil adsorption tests show that pyrolysis produced aerogels with greater adsorption capacity with an optimal mass ratio of 15 : 1 cellulose to PVA. Furthermore, the pseudo-second-order model was found to be more accurate than the pseudo-first-order model for the study of oil absorption kinetics. As a result, the modified cellulose aerogel is promising for replacing earth-unfriendly polymer-based oil sorbents due to their high oil absorption capacity.
Luong, Hoang Van,Long, Nguyen Van,Duong, Vu Binh,Toan, Nguyen Linh,Minh, Nguyen Van,Quang, Le Bach,Kim, Nam-Hyuck,Byun, Sang-Yo The Korean Society for Biotechnology and Bioengine 2009 KSBB Journal Vol.7 No.4
This study was initiated to investigate the impacts of media types and other components on the callogenensis and cell mass production of Panax vietnamensis in the first step of the cell biomass procedure. Four media were checked: Murashige-Skoog (MS), White, Gamborg and Nitch-AII. All the four media were shown potential media for Panax vietnamensis callogenensis and cell mass production, in which the MS medium showed the best results: the successful callogenensis ratio and cell mass formation were 30% and 62,93 ${\pm}$ 3,63 mg (DW) respectively, the Nitch medium showed the lowest results: the successful callogenensis ratio and cell mass formation were 15% and 27,10 ${\pm}$ 2,24 mg (DW) respectively. The results showed that the MS medium is the most suitable medium for Panax vietnamensis callogenensis and cell mass production.
Pentacyclic Triterpenoids from Mallotus apelta
Kiem, Phan-Van,Minh, Chau-Van,Huong, Hoang-Thanh,Nam, Nguyen-Hoai,Lee, Jung-Joon,Kim, Young-Ho The Pharmaceutical Society of Korea 2004 Archives of Pharmacal Research Vol.27 No.11
A new triterpene (1) and six known pentacyclic terpenoids (2-7) were isolated from the methanol extract of the dried leaves from Mallotus apelta. Based on the spectral and chemical evidence, their structures were determined to be 3$\alpha$-hydroxyhop-22(29)-ene (1), hennadiol (2), friedelin (3), friedelanol (4), epifriedelanol (5), taraxerone (6), and epitaraxerol (7).
Chemical Constituents of the Ficus elastica Leaves and Their Antioxidant Activities
Kiem, Phan Van,Minh, Chau Van,Nhiem, Nguyen Xuan,Tai, Bui Huu,Quang, Tran Hong,Anh, Hoang Le Tuan,Cuong, Nguyen Xuan,Hai, Truong Nam,Kim, Seung-Hyun,Kim, Jin-Kyoung,Jang, Hae-Dong,Kim, Young-Ho Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.10