• Korean Journal of Materials Research
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• v.23 no.3
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• pp.190-193
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• 2013

Spatial distributions of alloying elements of an Fe-based amorphous ribbon with a nominal composition of $Fe_{75}C_{11}Si_2B_8Cr_4$ were analyzed through the atom probe tomography method. The amorphous ribbon was prepared through the melt spinning method. The macroscopic amorphous natures were confirmed using an X-ray diffractometer (XRD) and a differential scanning calorimeter (DSC). Atom Probe (Cameca LEAP 3000X HR) analyses were carried out in pulsed voltage mode at a specimen base temperature of about 60 K, a pulse to base voltage ratio of 15 %, and a pulse frequency of 200 kHz. The target detection rate was set to 5 ions per 1000 pulses. Based on a statistical analyses of the data obtained from the volume of $59{\times}59{\times}33nm^3$, homogeneous distributions of alloying elements in nano-scales were concluded. Even with high carbon and strong carbide forming element contents, nano-scale segregation zones of alloying elements were not detected within the Fe-based amorphous ribbon. However, the existence of small sub-nanometer scale clusters due to short range ordering cannot be completely excluded.

• Advances in Traditional Medicine
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• v.4 no.1
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• pp.18-21
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• 2004

Six volunteers (mean $age=25.7{\pm}1.7$, $height=173{\pm}1.9$ and $weight=63.4{\pm}2.3{\;}kg$) participated in a graded exercise test and one hour of basic form of ChunDoSunBup (CDSB) Qi-training to investigate the cardiorespiratory responses and exercise intensity of Qi-training, a Korean traditional psychosomatic training. In the maximal exercise, the trainee showed $96.2{\pm}8.89{\;}l/min$ in ventilation (VE), $46.0{\pm}4.4$ in breath frequency (BF), $1.31{\pm}0.05$ in respiratory exchange ratio (RER), $180.7{\pm}3.0$ in heart rate (HR), and $2.6{\pm}1.1{\;}l/min$ or $40.7{\pm}2.3{\;}ml/kg/ml$ in oxygen consumption $(VO_2)$. Qi-training induced significant changes in BF, RER, HR, and $VO_2$. The exercise intensity of Qi-training were 42.3%, 46.9% and 38.7% of $HR_{max}$ during the sound exercise, slow motion (haeng-gong) and meditation respectively and the average was 46.2% of $HR_{max}$. We conclude that Qi-training is an aerobic exercise of a light (mild) intensity exercise, and it leads to decrease the metabolic rate in the trainee by breathing efficiently and relaxing them. In addition, Qi-training may affect cardiorespiratory function of BF, RER, HR and $VO_{2max}$ in trainees.

• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.65-76
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• 2021

There is a possibility of cavities occurring inside and behind the lining of an aged tunnel structure. In most cases, it is not easy to check the cavity because it exists in a place where visual inspection is impossible. Recently, attempts have been made to evaluate the condition of the tunnel lining and the backfill materials using non-destructive tests such as Ground Penetrating Radar, and various related model tests and numerical analysis studies have been conducted. In this study, the GPR signal characteristics for tunnel lining model testing were analyzed using gprMax software, which was compared with model test results. The numerical model applied to the model test reasonably simulated the electromagnetic wave signal according to the change of the material such as tunnel lining and internal cavity. Using the verified GPR model, B-scan data for the development of the GPR signal analysis technique were obtained, which can evaluate the thickness of the tunnel lining, the presence of the cavity, the effect of the waterproof membrane, and the frequency band.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.71-78
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• 2008

The paper proposes a chaotic double tent mapping PWM scheme for mitigation the acoustic noise of a motor chive. The chaos area ${\lambda}=0.99$ in bifurcation tree of the double tent mapping is used for generating the chaotic numbers. A 80C196 micro-controller is employed for generation of chaotic numbers, and the triangular carrier with chaotic frequency is obtained by using a 80C196 micro-controller and a MAX038 frequency modulator. The experiments are executed with a 1.5[kw] induction motor chive under the 2.5[A] load condition. As results, the experimental results show that the carrier, voltage and 3-D switching noise spectra of the proposed scheme is spread over the chaotic frequency range with no specific frequency concentration. Thereby, the shrill acoustic noise radiated from a motor chive is reduced by the proposed scheme.

• Journal of Acupuncture Research
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• v.22 no.5
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• pp.111-120
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• 2005

Objectives : The aim of this study is to investigate the effect of acupuncture stimulation on the relationship of change in magnetocardiography (MCG). Methods : For this purpose, 30 heart deficiency volunteers were acupunctured at Shinmun (HA7) and Naegwan (PC6) acupoint. Then, we measured and observed the change of frequency parameters in MCG. Results : In the mean frequency, during and after acupuncture treated groups of PC6 were decreased the activity of $f\;_{mean-max}$ compared to the control group. In the median frequency, during the acupuncture treated group of PC6 was decreased the activity of $f\;_{median-max}$ compared to the control group. Conclusion : These results suggested that acupuncture stimulation plays an important role to the activities of MCG.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.288-288
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• 2017

The seeds of soybean (Glycine max) were treated with different storage temperature for this study. The seeds of 3 accessions of soybean varieties in aluminum foil pack were used as materials. Storage temperature applied were $-18^{\circ}C$ and room temperature and seed banking (input after 3 days from output) frequencies were every 1, 6, and 12 month respectively for 9 years of storage period. As results seed banking frequency no affected to germination rate and seed moisture contents at $-18^{\circ}C$ storage room for seeds of soybean after 9 years. Germination rate of soybean seeds was changed from 96.2 % to 95.6 % averagely after 9 years of freezing ($-18^{\circ}C$) storage period. There were no differences in decreasing rate by number of seed banking frequency in soybean seeds. On the other hand, at room temperature germination rate of soybean seeds was decreased from 96.2 % to 27.3 % after 9 years which was decreased sharply to 55 % of initial viability after 6 years. The average rate of annual decrease of germination rate in soybean seeds was 38 % of initial viability at room temperature. Initial moisture contents of soybean seeds were 7.3 % and changed to 7.1 % at $-18^{\circ}C$ while it changed from 7.4 % to 7.0 % at room temperature after 9 years of storage period.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.9-16
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• 2000

MOS transistors are fabricated and evaluated for RF IC applications such as mobile communication systems using 0.35m CMOS process. Characteristics of MOSFETs are analyzed at various channel length, width and bias conditions. From the analysis, cut-off frequency ($f_T$) is independent on channel width but maximum oscillation frequency ($f_{max}$) tends to derease as the channel width increases. As channel length increases, $f_T$ and fmax decrease. $f_T$ is 22GHz and fmax is 28GHz at its maximum value. High frequency noise performance is improved with larger channel width and smaller channel length at same bias conditions. NFmin at 2GHz is 0.45dB as a minimum value. From the evaluation, MOSFETs designed using 0.35m CMOS process demonstrated a full potential for the commercial RF ICs for mobile communication systems near 2GHz. And optimization methods of the CMOS transistors for RF applications are presented in this paper.

• Journal of electromagnetic engineering and science
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• v.17 no.3
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• pp.147-152
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• 2017

This paper presents a frequency doubler operating at G-band that exceeds the maximum oscillation frequency ($f_{max}$) of the given transistor technology. A common-source transistor is biased on class-B to obtain sufficient output power at the second harmonic frequency. The input and output impedances are matched to achieve high output power and high return loss. The frequency doubler is fabricated in a commercial 150-nm GaAs pHEMT process and obtains a measured conversion gain of -5.5 dB and a saturated output power of -7.5 dBm at 184 GHz.

• Smart Structures and Systems
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• v.11 no.1
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• pp.123-134
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• 2013

Identifying structural modal parameters, especially those modes within high frequency range, from ambient data is still a challenging problem due to various kinds of uncertainty involved in vibration measurements. A procedure applying an ensemble empirical mode decomposition (EEMD) method is proposed for accurate and robust structural modal identification. In the proposed method, the EEMD process is first implemented to decompose the original ambient data to a set of intrinsic mode functions (IMFs), which are zero-mean time series with energy in narrow frequency bands. Subsequently, a Sub-PolyMAX method is performed in narrow frequency bands by using IMFs as primary data for structural modal identification. The merit of the proposed method is that it performs structural identification in narrow frequency bands (take IMFs as primary data), unlike the traditional method in the whole frequency space (take original measurements as primary data), thus it produces more accurate identification results. A numerical example and a multiple-span continuous steel bridge have been investigated to verify the effectiveness of the proposed method.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.135-140
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• 2005

Although it was recently observed that severe fatigue damage was formed in Al or Cu interconnects due to the cyclic temperatures generated by Joule heating of the metal lines by the passage of alternating currents (AC), AC loading frequency effect on the damage evolution characteristics are not known so far. This work focused on the effect of AC loading frequency (100 Hz vs. 10 kHz) on the thermo-mechanical fatigue characteristics by using polycrystalline sputtered Cu lines with temperature cycles with amplitudes from 100 to $300^{\circ}C$. It was consistently observed that higher loading frequency accelerated damaged grain growth and led to earlier failure irrespective of Cu grain sizes. The frequency effect is believed to result from differences in the concentration of defects created by the deformation-induced motion of dislocations to the grain boundaries.