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유전자 알고리즘을 이용한 Satellite Digital Audio Radio System Antennas 개발
김용진(Yongjin Kim),김상욱(Sanguk Kim),김진환(Jinhwan Kim),이용근(Yonggeun Kim),김영봉(Youngbong Kim) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.11
The Design and Optimization of a low-profile antenna for the Satellite Digital Audio Radio System (SDARS) using a Non-Dominated Sorting Genetic Algorithm (NSGA) is presented. a fairly omni-directional elevation gain pattern over 60 degrees < q <60 degrees are obtained. The average value of the LCP gain pattern is approximately 2 ㏈ic. The heights of the antennas are less than 0.251. The cross polarized signal level is approximately 12 ㏈ic less than the co-polarized signal level.
트러스트 요크를 이용한 HDD용 스핀들모터의 베어링 설계
김상욱(Sanguk Kim),김용진(Yongjin Kim),김진환(Jinhwan Kim),이용근(Yonggeun Kim),김영봉(Youngbong Kim) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.11
This paper is presented for the design of the thrust yoke for the spindle motors. HDD spindle motors are rotated by fluid dynamic bearing which consists of the shaft and the sleeve with the groove to generate the pressure. Because the thrust and journal clearances between shaft and sleeve is too small, around Bum and 2.5um, respectively, it is very difficult to design the bearing to come up to the disks to read and write the data. By the way, it is also so hard to overcome the load of the disks with only the thrust bearing. So, the paper is proposed for the trust yoke to come up to the disks considering of the force of the thrust bearing. In this paper, we proposed the thrust yoke with an unique fluid dynamic bearing in comparison with the motors without thrust yoke. Experimental results show the performance of the thrust yoke of the spindle motors for an HDD.
김상욱(Sanguk Kim),김진환(Jinhwan Kim),이용근(Yonggeun Kim),김보열(Boyoul Kim),김영봉(Youngbong Kim) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.10
This paper is presented for the measurement of the bearing stiffness for the spindle motors. BLDC Spindle Motors for the Hard Disk Drive are used by several kinds of the bearings, such as ball bearing, fluid dynamic bearing, and aero dynamic bearing. The spindle motors are attached the platters to read and write the data. Because the platter rotates at high end speed with the load and can be shocked from a suddenly moving, the bearing needs the rated stiffness with the pressure. By the way, it has not been realized to measure the real stiffness for each bearing types. In this paper, we proposed the method of measuring the stiffness for the bearings by using the magnet force. Experimental results show the performance to measure the bearing stiffness of the BLDC spindle motors for an HDD.
Disinfection of Iceberg Lettuce by Titanium Dioxide-UV Photocatalytic Reaction
KIM, YOUNGBONG,CHOI, YOONJUNG,KIM, SOOHYUN,PARK, JONGHYUN,CHUNG, MYONGSOO,SONG, KYUNG BIN,HWANG, INGYUN,KWON, KISUNG,PARK, JIYONG International Association for Food Protection 2009 Journal of food protection Vol.72 No.9
<P>Securing the physical quality and microbial safety of fresh foods has been a major focus in the food industry. To improve quality and increase the shelf life of fresh produce, disinfection methods have been developed. Titanium dioxide (TiO2) photocatalytic reactions under UV radiation produce hydroxyl radicals that can be used for disinfection of foodborne pathogenic bacteria. We investigated the effects of TiO2-UV photocatalytic disinfection on the shelf life of iceberg lettuce. Counts of natural microflora (total aerobic bacteria, coliforms, psychrotrophic bacteria, and yeasts and molds) and inoculated pathogenic bacteria (Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Salmonella Typhimurium) on iceberg lettuce were determined after 20-min treatments with TiO2-UV, UV radiation, a sodium hypochlorite (NaOCl) solution, and tap water. TiO2-UV treatment reduced the number of microorganisms by 1.8 to 2.8 log CFU/g compared with reductions of 0.9 to 1.4 and 0.7 to 1.1 log CFU/g obtained with UV radiation and NaOCl treatments, respectively. Treatment with tap water was used as a control and resulted in no reductions. Counts of microflora for iceberg lettuce at 4 and 25°C were determined during a 9-day period. TiO2-UV treatment resulted in 1.2- and 4.3-log increases in the counts of total aerobic bacteria at 4 and 25°C, respectively, compared with 1.3- to 1.6-log and 4.4- to 4.8-log increases due to UV radiation and NaOCl treatments.</P>
Periodic Ground Structure for C-PHY Signaling in Mobile Applications
TaeWoong Kim,YoungBong Han,Hung Khac Le,JongWan Shim,KwangMo Yang,BumHee Bae,SoYoung Kim 대한전자공학회 2021 Journal of semiconductor technology and science Vol.21 No.5
In this paper, we propose periodic slit ground structure (PSG) to improve the signal integrity of multilevel signals at high data rate such as MIPI C-PHY. Periodic slits are added in the upper and lower ground planes of the stripline structure, without adding additional layers or increasing area, to reduce crosstalk among neighboring lines. The proposed PSG structure can effectively improve the eye-diagram, especially eye height (EH) in multilevel signaling. The effectiveness of the proposed structure is validated through simulation and measurement of PCB-flexible printed circuit board (FPCB)-PCB structure that emulates the interconnected system of MIPI C-PHY signal transmission in a mobile system. The measurements from the test structures show that at a 2.5 Gsps data rate condition, the PSG structures show improvement in EH and eye width (EW) by 38.6% and 9.7%, respectively, compared to stripline structures. The proposed idea can be generally applied in PCB designs that will be used in high speed multilevel signal transmission to improve EH.