• Korean Journal of Materials Research
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• v.15 no.10
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• pp.621-625
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• 2005

Effects of rf power, pressure, sputtering gas composition, and substrate temperature on the deposition rate of the $WC_x$ coatings were investigated. The effects of rf power and sputtering gas composition on the hardness and corrosion resistance of the $WC_x$ coatings deposited by reactive sputtering were also investigated. X-ray diffraction (XRD) and Auger electron spectroscopy (AES) analyses were performed to determine the structures and compositions of the films, respectively. The hardnesses of the films were investigated using a nanoindenter, scanning electron microscopy, ana a salt-spray test, respectively. The deposition rate of the films was proportional to rf power and inversely proportional to the $CH_4$ content of $Ar/CH_4$ sputtering gas. The deposition rate linearly increased with increasing chamber pressure. The hardness of the $WC_x$ coatings Increased as rf power increased. The highest hardness was obtained at a $Ar/CH_4$ concentration of $10 vol.\%$ in the sputtering gas. The hardness of the $WC_x$ film deposited under optimal conditions was found to be much higher than that of the electroplated chromium film, although the corrosion resistance of the former was slightly lower than that of the latter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.3
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• pp.340-347
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• 2004

Ultra-small size, high-performance, solenoid-type RF chip inductors utilizing low-loss A1$_2$O$_3$ core materials were investigated. The dimensions of the RF chip inductors fabricated were 1.0mm${\times}$0.5mm${\times}$0.5mm and copper coils were used. The materials (96％ A1$_2$O$_3$) and shape (I-type) of the core, the diameters (40${\mu}{\textrm}{m}$) and position (middle) of the coil, and the lengths (0.35mm) of solenoid were determined by a high-frequency structure simulator (HFSS) to maximize the performance of the inductors. The high-frequency characteristics of the inductance (L) and quality-factor (Q) of the developed inductors were measured using a RF impedance/material analyzer (E4991A with E16197A test fixture). The developed inductors exhibit an inductance of 11 to 11.3nH and a qualify factor of 22.3 to 65.7 over the frequency ranges of 250 MHz to 1.7 GHz, and show results comparable to those measured for the inductors prepared by Coilcraft$^{TM}$. The simulated data described the high-frequency data of the L and Q of the fabricated inductors well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2163-2170
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• 2012

A signal receiving system can measure and analyze frequency, pulse modulation, scan modulation, frequency modulation on pulse, phase modulation on pulse of RF signal. A signal receiving system should be verified under simulated RF signal environment prior to verification on operation in fields. This paper describes an effective method to generate simulated RF signals with considering operational scenario. The simulated RF signal generator can be effectively used to evaluate the performance of the signal receiver and reduce the test cost of the signal receiver.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.501-507
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• 2003

In this study, microscale, high-performance, solenoid-type RF chip inductors were investigated. The size of the RF chip inductors fabricated in this work was 1.0${\times}$0.5${\times}$0.5㎣. 96% $Al_2$ $O_3$and I-type were used as the material and shape of the core, respectively. The copper (Cu) wire with 6 turns was employed as the coils. The diameter (40${\mu}{\textrm}{m}$) and position (middle) of the coil and the length (0.35mm) of solenoid were determined by a high-frequency structure simulator (HFSS) to maximize the performance of the inductors. High frequency characteristics of the inductance (L) and quality-factor (Q) of developed inductors were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). The inductors developed have inductances of 10.8nH and quality factors of 25.2 to 50 over the frequency ranges of 250MHz to l GHz, and show results comparable to those measured for the inductors prepared by CoilCraf $t^{Tm}$ . The simulated data predicted the high-frequency data of the L and Q of the inductors developed well.l.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.10 s.101
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• pp.1020-1027
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• 2005

In this paper, economic miniature RF transmitter module for intelligent transportation system(ITS) is described. This module which consists of ASK modulator, frequency synthesizer, power amplifier is operating at 5.8 GHz frequency band and implemented by using LTCC process technique. Thus, ultra small size of 0.8 CC and improved electrical performances has been obtained. From the test results, transmitting characteristics of 10 dBm ouput power and -46 dBc interchannel interference with 1.024 Mbps ASK modulated have been shown. Frequency synthesizer as a transmitting signal source reveals very short locking time of 26 usec and outstanding phase noise of -115 dBc/Hz at 1 MHz offset from 5.8 GHz center frequency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.840-846
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• 2000

In this work, small-size, high-performance solenoid-type RF chip inductors utilizing a low-loss Al$_2$O$_3$core material were investigated. The size of the chip inductors fabricated in this work were 15$\times$10$\times$0.7㎣, 2.1$\times$1.5$\times$10㎣, and 2.4$\times$2.0$\times$1.4㎣ and copper (Cu) wire with 40 ㎛ diameter was used as the coils. High frequency characteristics of the inductance, quality factor, and impedance of developed inductors were measured suing an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). It was observed that the developed inductors with the number of turns of 7 have the inductance of 33 to 100nH and exhibit the self-resonant frequency (SRF) of .26 to 1.1 GHz. The SRF of inductors decreases with increasing the inductance and the inductors have the quality factor of 60 to 80 in the frequency range of 300 MHz to 1.1 GHz. In this study, small-size solenoid-type RF chip inductors with high inductance and high quality factor were fabricated successfully. It is suggested that the thin film-type inductor is necessary to fabricate the smaller size inductors at the expence of inductance and quality factor values.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.73-80
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• 2022

Sensors are applied to small aviation platforms for various purposes. Radio frequency (RF) antennas, which are representative sensors, are available in many forms but require the application of slot array RF antennas to ensure high performance and designation. Slot RF array antennas are applied to dip brazing techniques, but the yield and production time are determined by the proficiency of production personnel in a labor-intensive form. Unmanned aerial vehicles or drones, which are representative small aviation platforms, are continuously exposed to various random vibrations because propellers and multiple power sources are used in them. In this study, the fatigue life of slot array RF antennas applied with additive manufacturing was evaluated through the cumulative damage method (Miner's rule) in a vibration environment with a small aviation platform. For the evaluation, an S N curve obtained from a fatigue strength test was used.

• Korean Journal of Psychosomatic Medicine
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• v.25 no.1
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• pp.33-45
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• 2017

Objectives : The purpose of this study was to examine psychological characteristics of patients who visited psychiatric clinic for medical certificate for military service using MMPI-2-RF. We compared target group with general psychiatric patients with same age range. Methods : A total of 165 male patients for medical certificate and 154 general psychiatric patients were collected from the Department of Psychiatry of three university hospitals. There were significant differences of age and educational level between two groups. We used independent t-test, ANCOVA, ${\chi}^2$ test to examine differences between two groups. Results : Medical certificate group scored higher on the validity scales, the Higher-Order(H-O) scales, the Restructured Clinical(RC) Scales, the Specific Problems(SP) Scales, and the Personality Psychopathology Five (PSY-5) Scales. Especially, EID, RC7, HLP, SFD, SAV, SHY, DSF, and INTR-r showed significant differences between two groups on all three statistical tests. Conclusions : The present study showed that psychiatric patients who received psychological evaluation for military service have significantly higher emotional distress, helplessness, lower self-confidence, and lower quality of interpersonal relationships. And the difference of validity scales between two groups could be related with psychological burden of compulsory military service in the study sample which causes elevation on scales of infrequent responses. MMPI-2-RF would be helpful instrument to assess these emotional and psychological characteristics.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.2 s.5
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• pp.41-53
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• 2004

This study introduces the process of the field test of ETCS that has been performed by six enterprises for selecting the type of ETCS that will be applied to the internal tall roads. The main communication modes of six enterprises are active RF(radio wave)type and IR(optical wave)type. In this study, communication modes and systems, which are being used by each enterprises, have been compared and analyzed. Besides this, the configuration and the basic performances of the system have been checked. After those, the contents of the field performance test classified by the items of the test and the results of the test, finally, have been analyzed. Through analyzing the test, it is found that an enterprise using IR type and two enterprises using RF type satisfied the standards of the test and the others failed to meet the standards. However, the enterprises seem to be becoming stable by a large number of tests and the effort for improving from general point of view. Although the methods of performance evaluation in this field test considered enough patterns that are used in the present highway or Hi-Pass, there might possibly be some problems in the results because Korea Highway Corporation had decided the method and the number of times of the test according to their own standards about the various situations that can happen. Therefore, it will be needed to develop the method of standards for testing the performance which can be correspond with driver's behavior that can actually happen on the highway or the methods of transportation management.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.10
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• pp.17-23
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• 2003

In this study, microscale, high-performance, solenoid-type RF chip inductors were investigated. The size of the RF chip inductors fabricated in this work was 1.0${\times}$0.5${\times}$0.5㎣. The materials (96% Al2O3) and shape (I-type) of the core were determined by a Maxwell three-dimensional field simulator to maximize the performance of the inductors. The copper (Cu) wire with 40${\mu}{\textrm}{m}$ diameter was used as the coils. High frequency characteristics of the inductance (L), quality-factor (Q), and capacitance (C) of developed inductors were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). The inductors developed have inductances of 11 to 39 nH and quality factors of 28 to 50 over the frequency ranges of 250MHz to 1 GHz, and show results comparable to those measured for the inductors prepared by CoilCraf $t^{Tm}$ that is one of the best chip inductor company in the world. The simulated data predicted the high-frequency data of the L, Q, and C of the inductors developed well.l.