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Simple fabrication method of the unique micro/nano structures using synchrotron X-ray
Kanghyun Kim(김강현),Kyungjin Park(박경진),Geunbae Lim(임근배),Jong Hyun Kim(김종현) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Micro- and nanofluidic devices are being used increasingly in biological, chemical, and medical applications, and many fabrication methods have been proposed. Using the fabricated nanochannels, the generation of ion concentration polarization, a novel transport phenomenon in nanofluidics, was investigated. Our novel fabrication method should be a useful tool for various nanofluidic applications due to its various advantages, including simple fabrication process, controllability, and duplicability. Conventional micro fabrication techniques have been improved to overcome their limitations by developing various methods with a three-dimensional structure. Three dimensional structure or various patterns in shape have been realized, but the process is slightly complicated and the efficiency is low. Nowadays, more efficient and simple fabrication methods are required for the application of various micro-structure based components/devices and systems. In this study, we developed novel fabrication technique to fabricate various tilted micro-structures with a different angle on single substrate using a synchrotron X-ray lithography. Here, we have shown the unique fabrication technique which is based on synchrotron x-ray irradiation and curved/flexible x-ray mask/substrate. Tilted microstructure can have various angles and directions in single substrate.
엑스선 그레이 스케일 리소그래피를 활용한 반원형 단면의 서브 마이크로 선 패턴의 바이오멤스 플랫폼 응용
김강현 ( Kanghyun Kim ),김종현 ( Jong Hyun Kim ),남효영 ( Hyoryung Nam ),김수현 ( Suhyeon Kim ),임근배 ( Geunbae Lim ) 한국센서학회 2021 센서학회지 Vol.30 No.3
As the rising attention to the medical and healthcare issue, Bio-MEMS (Micro electro mechanical systems) platform such as bio sensor, cell culture system, and microfluidics device has been studied extensively. Bio-MEMS platform mostly has high resolution structure made by biocompatible material such as polydimethylsiloxane (PDMS). In addition, three dimension structure has been applied to the bio-MEMS. Lithography can be used to fabricate complex structure by multiple process, however, non-rectangular cross section can be implemented by introducing optical apparatus to lithography technic. X-ray lithography can be used even for sub-micron scale. Here in, we demonstrated lines with round shape cross section using the tilted gold absorber which was deposited on the oblique structure as the X-ray mask. This structure was used as a mold for PDMS. Molded PDMS was applied to the cell culture platform. Moreover, molded PDMS was bonded to flat PDMS to utilize to the sub-micro channel. This work has potential to the large area bio-MEMS.
KIM, Kanghyun,BU, Youngmin,JEONG, Seungil,LIM, Jongpil,KWON, Youngan,CHA, Dong Seok,KIM, Jinmo,JEON, Sora,EUN, Jaesoon,JEON, Hoon Japan Society for Bioscience, Biotechnology, and A 2006 Bioscience, Biotechnology, and Biochemistry Vol.70 No.8
<P><I>Abies koreana</I> Wilson (<I>A. koreana</I>) is a shrub or broadly pyramidal evergreen tree endemic in the mountainous regions of South Korea. We obtained the essential oil (EO) from alpine needle leaves of <I>A. koreana</I> by the supercritical fluid extraction (SFE) method. EO was analyzed by gas chromatography–mass spectrometry (GC–MS), and 68 compounds were identified constituting 95.66% of the oil. The major components were elemol (11.17%), terpinen-4-ol (9.77%), sabinene (8.86%), 10(15)-cadien-4-ol (7.16%), α-terpineol (6.13%), α-pinene (6.07%) and γ-terpinene (4.71%). To investigate the memory-enhancing effects, we conducted a passive avoidance test using a scopolamine (1 mg/kg, ip)-induced amnesia mouse model. A peritoneal injection of EO from <I>A. koreana</I> (100 mg/kg) showed a memory enhancing effect of 72.7% compared with the control. These results suggest that EO of <I>A. koreana</I> may be a useful therapeutic agent against such amnesia-inducing diseases as Alzheimer and vascular dementia.</P>
Park, Hi-Joon,Lim, Sabina,Joo, Wan-Seok,Yin, Chang-Shik,Lee, Hyang-Sook,Lee, Hye-Jung,Seo, Jung-Chul,Leem, Kanghyun,Son, Yang-Sun,Kim, Youn-Jung,Kim, Chang-Ju,Kim, Yong-Sik,Chung, Joo-Ho WHO COLLABORATING CENTRE FOR TRADITIONAL MEDICINE 2003 東西醫學硏究所 論文集 Vol.2003 No.-
Parkinson's disease (PD) is a chronic neurodegenerative disorder, and it has been suggested that treatments promoting survival and functional recovery of affected dopaminergic neurons could have a significant and long-term therapeutic value. In the present study, we investigated the neuroprotective effects of acupuncture on the nigrostriatal system in rat unilasterally lesioned with 6-hydroxydopamine (6-OHDA, 4 ㎍/㎕, intrastriatal injection) using tyrosine hydroxylase (TH) and receptor for brain-denved neruotrophic factor, trkB, immunohistochemistries. Two weeks after the lesions were made, rats presented with asymmetry in rotational behavior (118.3 ± 17.5 turns/h) following injection with apomorphine, a dopamine receptor agonist (0.5 ㎎/㎏, sc). In contrast, acupunctural treatment at acupoints GB34 and LI3 was shown to significantly reduce this motor deficit (146 ± 13.4 turns/h). Analysis via TH immunohistochemustry revealed a substantial loss of cell bodies in the substantia nigra (SN) (45.7% loss) and their terminals in the dorsolateral striatum ipsilateral to the 6-OHDA-induced lesion. However, acupunctural treatment resulted in the enhanced survival of dopaminergic neurons in the SN (21.4% loss) and their terminals in the dorsolateral striatum. Acupuncture also increased the expression of trkB significantly (35.6% increase) in the ipsilateral SN. In conclusion, we observed that only acupuncturing without the use of any drug has the neuroprotective effects against neuronal death in the rat PD model and these protective properties of acupuncture could be mediated by trkB.
CNT-Au nanocomposite deposition on gold microelectrodes for improved neural recordings
Kim, Geon Hwee,Kim, Kanghyun,Nam, Hyoryung,Shin, Kumjae,Choi, WooSeok,Shin, Jung Hwal,Lim, Geunbae Elsevier 2017 Sensors and actuators. B, Chemical Vol.252 No.-
<P><B>Abstract</B></P> <P>Microelectrode arrays (MEAs) are widely used in neural recordings of cultured neurons and neural tissues. The impedance of neural electrodes is an important factor because it determines the signal-to-noise ratio (SNR) of the recorded neural signals. Here, we developed a modified technique using CNT-Au nanocomposites (CANs) for MEAs. The impedance of CAN-modified microelectrodes was greatly decreased <I>versus</I> pure gold microelectrodes due to their large electrochemical surface area (ESA). Importantly, when compared in terms of “impedance with respect to surface area” with previous reports, the value was 8.8MΩμm<SUP>2</SUP>, which is outstanding. Cultured neurons showed good viability and the SNR (average SNR=92) of recorded neural signals with CAN-modified microelectrodes was sufficiently high compared with previous studies. This modified technique will provide a significant advancement in MEA chips and could also be applied to various neural electrodes, such as Si electrodes, multiple site electrodes, and tetrodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The hierarchical structure was developed using CANs to enhance the electrochemical surface area (ESA) of MEA electrode. </LI> <LI> The MEA impedance modified with CANs was reduced by approximately 99.3% compared with pure gold microelectrode, and the impedance magnitude was around 50kΩ. </LI> <LI> Comparing the “impedance with respect to surface area (=ІZІ<SUB>at1kHz</SUB> ×surface area)” with previous studies, <B> <I>the value of our results is ranked third in the 11 previous studies</I> </B>. </LI> <LI> <B> <I>The recording performance</I> </B> (peak amplitude: 340–470μV<SUB>pp</SUB>, noise level: 3.5-5.3μV<SUB>rms</SUB>) <B> <I>is outstanding compared to previous reports</I> </B> (peak amplitude: 100–500μV<SUB>pp</SUB>, noise level: 3–5μV<SUB>rms</SUB>). </LI> </UL> </P>
Ionic liquid flow along the carbon nanotube with electric field
Jung Hwal Shin(신정활),Kanghyun Kim(김강현),WooSeok Choi(최우석),Geunbae Lim(임근배) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Liquid pumping can occur along the outer surface of an electrode under a DC electric field. For biological applications, a better understanding of the ionic solution pumping mechanism is required. Here, we fabricated CNT wire electrodes (CWEs) and tungsten wire electrodes (TWEs) of various diameters to assess an ionic solution pumping. A DC electric field created by a bias of several volts pumped the ionic solution in the direction of the negatively biased electrode. The resulting electro-osmotic flow was attributed to the movement of an electric double layer near the electrode, and the flow rates along the CWEs were on the order of picoliters per minute. According to electric field analysis, the z-directional electric field around the meniscus of the small electrode was more concentrated than that of the larger electrode. Thus, the pumping effect increased as the electrode diameter decreased. Interestingly in CWEs, the initiating voltage for liquid pumping did not change with increasing diameter, up to 20 ㎛. We classified into three pumping zones, according to the initiating voltage and faradaic reaction. Liquid pumping using the CWEs could provide a new method for biological studies with adoptable flow rates and a larger ‘Recommended pumping zone’.
Design and Vibration Analysis of Tri-axis Linear Vibratory MEMS Gyroscope
Seok, Seyeong,Moon, Sanghee,Kim, Kanghyun,Kim, Suhyeon,Yang, Seongjin,Lim, Geunbae The Korean Sensors Society 2017 센서학회지 Vol.26 No.4
In this study, the design of a tri-axis micromachined gyroscope is proposed and the vibration characteristic of the structure is analyzed. Tri-axis vibratory gyroscopes that utilize Coriolis effect are the most commonly used micromachined inertial sensors because of their advantages, such as low cost, small packaging size, and low power consumption. The proposed design is a single structure with four proof masses, which are coupled to their adjacent ones. The coupling springs of the proof masses orthogonally transfer the driving vibrational motion. The resonant frequencies of the gyroscope are analyzed by finite element method (FEM) simulation. The suspension beam spring design of proof masses limits the resonance frequencies of four modes, viz., drive mode, pitch, roll and yaw sensing mode in the range of 110 Hz near 21 kHz, 21173 Hz, 21239 Hz, 21244 Hz, and 21280 Hz, respectively. The unwanted modes are separated from the drive and sense modes by more than 700 Hz. Thereafter the drive and the sense mode vibrations are calculated and simulated to confirm the driving feasibility and estimate the sensitivity of the gyroscope. The cross-axis sensitivities caused by driving motion are 1.5 deg/s for both x- and y-axis, and 0.2 deg/s for z-axis.
자동변속기 I/P Shaft 비틀림 내구 시험방법 생성에 관한 연구
이규호(KyooHo Lee),이현우(Hyunwoo Lee),이강현(KangHyun Lee),박기종(Ki-Jong Park),임채홍(ChaeHong Lim) 한국자동차공학회 2006 한국자동차공학회 Symposium Vol.- No.-
To generate component test condition of the Input shaft, T-N Curve is generated and the Road Load Data for Automatic Transmission Input shaft is measured by strain gage and slip ring. The measured data is classified by Rainflow counting method to find the amplitude and mean torque class. As a result, the degree of severity between component test and Power train durability test is compared. The new designed input shaft has 2 times longer B10 life. Finally, the CAE result has good correlation with the corresponding test result on the current and improved designs.