• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.42-48
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• 2011

In this paper, a passive load-pull using a GaN HEMT (Gallium Nitride High Electron Mobility Transistor) bare-chip in X-band is presented. To obtain operation conditions that characteristic change by self-heating was minimized, pulsed drain bias voltage and pulsed-RF signal is employed. An accuracy impedance matching circuits considered parasitic components such as wire-bonding effect at the boundary of the drain is accomplished through the use of a electro-magnetic simulation and a circuit simulation. The microstrip line length-tunable matching circuit is employed to adjust the impedance. The measured maximum output power and drain efficiency of the pulsed load-pull are 42.46 dBm and 58.7%, respectively, across the 8.5-9.2 GHz band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2417-2424
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• 2016

Small size and light weight is very important for components used in radar mounted platform such as airborne radar. Recently, the active phased array radar is developed as an array of antennas for thousands of transmit/receive modules to be used as a multi-function radar that can detect and track targets. In this case, the size and weight of the transmit/receive modules are critical factor for developing the radar. In this paper, we developed a compact transmit/receive module using the 10W RF MEMS switch domestically localizing and reduced the circuit area to about 86.5% compared to using a circulator. The developed module satisfies not only electrical requirements but also MIL-STD's environmental specifications. So it can be used in a military device. It can be used at adaptive tunable receivers, reconfigurable smart active antennas and wide band beam electrical steering antennas.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.614-622
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• 1999

Recent studies have implicated that more rostral components of the trigeminal spinal nucleus including subnucleus oralis (Vo) in orofacial nociceptive mechanisms. Since there is only limited electrophysiological evidence, the present study was initiated to characterize the receptive field and response properties of malls nociceptive neurons in chloralose/urethan-anesthetized rats. Single neuronal activity was recorded in right subnucleus oralis, and types of nociceptive neurons classified wide dynamic range (WDR), NS (nociceptive specific) and deep nociceptive (D) and the mechanoreceptive field (RF) and response properties were determined. A total of 34 nociceptive neurons could be subdivided into 17WDR neurons, 12NS neurons and 5D neurons. Vo nociceptive neurons had RF involving maxillary and/or mandibular divisions mainly located in the intraoral and/or perioral regions. Majority of Vo nociceptive neurons showed spontaneous activity less than 1Hz. The NS and D neurons activated only by heavy pressure and/or pinch stimuli had high mechanical thresholds compared to WDR neurons activated also by tactile stimuli. Vo nociceptive neurons showed a progressive increase of response to the graded mechanical stimuli. 39% of Vo nociceptive neurons received C-fiber electrical input as well as A-fiber electrical input from their RF, and 45% of them responded to electrical stimulation of the right maxillary first molar. 41% of Vo nociceptive neurons responded to noxious heat applied to their RF, and 18% of them showed an immediate burst of discharges following MO application to the right maxillary first molar pulp. These results indicate that Vo is involved in the transmission of nociceptive information mainly coming from intraoral or perioral region including tooth pulp.

• Journal of Korean Society of Forest Science
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• v.82 no.4
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• pp.431-440
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• 1993

This study was carried out to clarify a taxonomical relationships of the Korean Theaceae using characters from morphological, anatomical, electrophoretic and numerical methods. The results are summarized as follows ; Morphological data were cluster analysis by Euclidean distance, the complete and average linkage cluster were most distinctly classified into subfamily level. At the principal components analysis(PCA), the commutative contribution rate of three principal components showed to 91.1% total variance. By the leaf venation were classified semicraspedromous type of Theoideae and brochidodromous type of Ternstroemioideae. The stomatal types were classified Paracytic of Theoideae and Anomocytic type of Ternstroemioideae ; the former has founded subsideary cell the latter has not found. All taxa possessed common isozyme bands did not found out of Theaceae banding patterns. But, the activity of Theoideae were existed in below No.5(Rf. 4.0-4.4), in contrast to Ternstroemioideae were existed in more than No.7(Rf. 5.7-6.2). The cluster analysis of leaf characters and peroxidase isozymes were similarity between two methods.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.2
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• pp.208-214
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• 2024

This reports the electrical properties of single-crystal β-gallium oxide (β-Ga₂O₃) vertical Schottky barrier diodes (SBDs) with a different guard ring structure. The vertical Schottky barrier diodes (V-SBDs) were fabricated with two types guard ring structures, one is with metal deposited on the Al₂O₃ passivation layer (film guard ring: FGR) and the other is with vias formed in the Al₂O₃ passivation layer to allow the metal to contact the Ga₂O₃ surface (metal guard ring: MGR). The forward current values of FGR and MGR V-SBD are 955 mA and 666 mA at 9 V, respectively, and the specific on-resistance (R_on,sp) is 5.9 mΩ·cm² and 29 mΩ·cm². The series resistance (R_s) in the nonlinear section extracted using Cheung's formula was 6 Ω, 4.8 Ω for FGR V-SBD, 10.7 Ω, 6.7 Ω for MGR V-SBD, respectively, and the breakdown voltage was 528 V for FGR V-SBD and 358 V for MGR V-SBD. Degradation of electrical characteristics of the MGR V-SBD can be attributed to the increased reverse leakage current caused by the guard ring structure, and it is expected that the electrical performance can be improved by preventing premature leakage current when an appropriate reverse voltage is applied to the guard ring area. On the other hand, FGR V-SBD shows overall better electrical properties than MGR V-SBD because Al₂O₃ was widely deposited on the Ga₂O₃ surface, which prevent leakage current on the Ga₂O₃ surface.

• Korean Journal of Pharmacognosy
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• v.3 no.1
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• pp.23-25
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• 1972

Preliminary investigations were carried out to isolate the constituents from the stems of genus Thalictrum. Methanol extracts of eight species from the genus were examined by thin layer chromatography. The author observed three different spots with Dragendorff's reagent in Thalictrum actaefolium, whereas none was detected in Thalictrum tuberiferum and Thalictrum simplex. Various fluorescent colors with different Rf values were detected in all species by UV ray, suggesting that each species may have different components.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.939-942
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• 1998

This paper presents the process on the construction for the remote distribution pole transformer monitoring system. Especially, this system uses CATV cable as communication media which is located in KEPCO's main distribution line. It has four major components such as sensor for measuring secondary voltage and currents of distribution transformer, RF modem for data modulating/de-modulating, communication media for sending/receiving of data, and pc server for monitoring the results of sensing or computing information. This paper also describes the configuration of these each component's configuration and its functions.

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.245.2-245.2
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• 2003

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.111-114
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• 2001

Optical transmitter and receiver are the essential components for optical communication. For these components, butterfly type packages are used which are comprised of metal housing, multilayer ceramic inserts, lead and window. In this study, 2.5 Gbps DFB(Distributed -Feedback) LD(Laser Diode) package was fabricated and characterized. Metal housing showed good thermal conductivity (200W/mK) and well matched TCE(6.7ppm/K) with GaAs chip. Ceramic inserts also showed good VSWR(Voltage Standing Wave Ratio) characteristics(<2.0). By brazing technology, all the elements were combined and sealed. RF characteristics of the package mounted on the PWB was also tested.

• Korean Journal of Pharmacognosy
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• v.20 no.4
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• pp.227-232
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• 1989

As a part of studies on the quality control of crude drug preparation (So-Shi-Ho-Tang), index components of Glycyrrhizae Radix were identified by TLC and quantified by HPLC. Specific red spot (Rf=0.47) was identified in acid hydrolysate of glycosidic fraction on silica gel plate with benzene/ethyl acetate (1 : 1, v/v). The content of glycyrrhizin was determined by quantification of glycyrrhetinic acid by HPLC on ${\mu}-Bondapak\;C_{18}$ column with $MeOH/H_2O/HAc$ (78 : 19 : 3, v/v). Its recovery rate in the extract granules, compared to the content in the Glycyrrhizae Radix, was $83.3{\pm}0.7%$.