• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4A
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• pp.214-218
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• 2012

In this paper, we reported on a high performance waveguide VCO(voltage controlled oscillator) for FMCW applications. The waveguide VCO consists of a GaAs Gunn diode, a varactor diode, and two bias posts with low pass filter(LPF). The cavity is designed for fundamental mode at 47 GHz and operated at second harmonic of 94 GHz center frequency. The developed waveguide VCO has 1.095 GHz bandwidth, 590 MHz linearity with 1.69% and output power from 14.86 to 15.93 dBm. The phase noise is under -95 dBc/Hz at 1 MHz offset.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.11
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• pp.1082-1088
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• 2004

This paer presents a feedback-controlled, MEMS-fabricated microaccelerometer($\mu$XL). The $\mu$XL has received much commercial attraction, but its performance is generally limited. To improve the open-loop performance, a feedback controller is designed and experimentally evaluated. The feedback controller is applied to the x/y-axis $\mu$XL fabricated by sacrificial bulk micromachining(SBM) process. Even though the resolution of the closed-loop system is slightly worse than open-loop system, the bandwidth, linearity, and bias stability are stability are significantly improved. The noise equivalent resolution of open-loop system is 0.615 mg and that of closed-loop system is 0.864 mg. The bandwidths of open-loop and closed-loop system are over 100Hz. The input range, non-linearity and bias stability are improved from $\pm10\;g\;to\;\pm18g$, from 11.1%FSO to 0.86%FSO, and from 0.221 mg to 0.128 mg by feedback control, respectively.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.20-27
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• 2020

Sound event detection in real-world environments suffers from the interference of non-stationary and time-varying noise. This paper presents an adaptive noise reduction method for sound event detection based on non-negative matrix factorization (NMF). In this paper, we proposed a deep learning model that integrates Convolution Neural Network (CNN) with Non-Negative Matrix Factorization (NMF). To improve the separation quality of the NMF, it includes noise update technique that learns and adapts the characteristics of the current noise in real time. The noise update technique analyzes the sparsity and activity of the noise bias at the present time and decides the update training based on the noise candidate group obtained every frame in the previous noise reduction stage. Noise bias ranks selected as candidates for update training are updated in real time with discrimination NMF training. This NMF was applied to CNN and Hidden Markov Model(HMM) to achieve improvement for performance of sound event detection. Since CNN has a more obvious performance improvement effect, it can be widely used in sound source based CNN algorithm.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.110-116
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• 2012

To analyze flow characteristics and performance of the side jet thruster with 4 shutters and rectangular nozzles, a 3-D simulation has been implemented. Numerical calculations for three rotation anlgles of the shutter, have been conducted. Internal recirculation in a chamber and asymmetric flow structure in a nozzle were observed. In addition, the more shutter rotated, the more asymmetries of flow increased, and this phenomena resulted in thrust bias. The degrees of thrust bias and thrust performance with the rotation angles of the shutter were predicted and comparisons with theoretical thrust were made.

• Electronic Materials Letters
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• v.14 no.6
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• pp.749-754
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• 2018

Previous studies have reported on the mechanical robustness and chemical stability of flexible amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) on plastic substrates both in flat and curved states. In this study, we investigate how the polyimide (PI) substrate affects hydrogen concentration in the a-IGZO layer, which subsequently influences the device performance and stability under bias-temperature-stress. Hydrogen increases the carrier concentration in the active layer, but it also electrically deactivates intrinsic defects depending on its concentration. The influence of hydrogen varies between the TFTs fabricated on a glass substrate to those on a PI substrate. Hydrogen concentration is 5% lower in devices on a PI substrate after annealing, which increases the hysteresis characteristics from 0.22 to 0.55 V and also the threshold voltage shift under positive bias temperature stress by 2 ${\times}$ compared to the devices on a glass substrate. Hence, the analysis and control of hydrogen flux is crucial to maintaining good device performance and stability of a-IGZO TFTs.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.4
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• pp.235-243
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• 2018

Conventional Real Time Kinematics (RTK) collect measurements in stationary state for several minutes to resolve the integer ambiguity in the carrier phase measurement or resolve the integer ambiguity on the move assuming low maneuvering movement. In this paper, an On The Move-RTK (OTM-RTK) technique that resolves the integer ambiguity on the move for fast and precise positioning of ground vehicles such as high maneuvering vehicles was proposed. The OTM-RTK estimates the precise amount of movement between epochs using the carrier phase measurements acquired on the move, and by using this, resolves the integer ambiguity within a short period of time by evaluating the integer ambiguity candidates for each epoch. This study analyzed the integer ambiguity resolution performance using field driving experiment data in order to verify the performance of the proposed method. The results of the experiment showed that the precise trajectory including the initial position bias can be obtained prior to resolving the integer ambiguity, and after resolving the integer ambiguity on the move, it was possible to obtain the bias-corrected precise position solution. It was confirmed that the integer ambiguity can be resolved by collecting measurements of about 10 epochs from the moving vehicle using a dual frequency receiver.

• The Journal of Industrial Distribution & Business
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• v.13 no.8
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• pp.1-7
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• 2022

Purpose: The present study concentrates on the issues that affected the employees directly and acted as stress factors. These stress factors affect how the employees perform while undertaking their duties. Furthermore, this study evaluated how the involvement of the corporate counsel affected the company by enhancing the productivity of the employees. Research design, data and methodology: The research design of this research is a literature content analysis and method for data handling should be described, and the resultant combination of the studies should include the consistency measures for every meta-analysis. Specify any risk assessment of bias that may impact the cumulative evidence, such as the publication bias and the selective reporting within studies. Results: The finding shows that change in the location of employees' organizational restructuring and the introduction of new technologies also contributed to significant organizational stress factors. These results show a substantial correlation between the magnitude of the adjustments' effects on employees' performance. Conclusions: The current study strongly concludes that counselors, through their prowess, can analyze and evaluate the stress factors that are evident among the employees and in the organization. Some of these factors may be office layout, organizational codes of ethics, organization rules, and employees' personal challenges.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.62-66
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• 2023

With the advancement in technology and rapid increase in the demand for microelectromechanical systems (MEMS) based inertial measurement units (IMUs), high-volume production and test system remain a major challenge for the MEMS industry. To compete with the challenging market of Industry 4.0, here we developed an automatic test system to evaluate the performance of the ovenized IMU sensors as well as analyze the data. The automatic test system was developed by interfacing a commercial MEMS IMU (BMI 088) using LabVIEW. The BMI 088 was tested experimentally for long-term bias stability, ON/OFF bias repeatability, and root mean square (rms) noise. Furthermore, the data was analyzed through the developed test system. The results show that the automatic test system has improved the test time and reduced human effort. The developed automatic test system is a significant approach to MEMS research and development (R&D) to increase and improve the mass production of IMUs.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4518-4526
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• 2023

NECP-SARAX is a neutronics analysis code system for advanced reactor developed by Nuclear Engineering Computational Physics Laboratory of Xi'an Jiaotong University. In past few years, improvements have been implemented in TULIP code which is the cross-section generation module of NECP-SARAX, including the treatment of resonance interface, considering the self-shielding effect in non-resonance energy range, hyperfine group method and nuclear library with thermal scattering law. Previous studies show that NECP-SARAX has high performance in both fast and thermal spectrum system analysis. The accuracy of TULIP code in fast and thermal spectrum system analysis is demonstrated preliminarily. However, a systematic verification and validation is still necessary. In order to validate the applicability of TULIP code for full energy range, 147 fast spectrum critical experiment benchmarks and 170 thermal spectrum critical experiment benchmarks were selected from ICSBEP and used for analysis. The keff bias between TULIP code and reference value is less than 300 pcm for all fast spectrum benchmarks. And that bias keeps within 200 pcm for thermal spectrum benchmarks with neutron-moderating materials such as polyethylene, beryllium oxide, etc. The numerical results indicate that TULIP code has good performance for the analysis of fast and thermal spectrum system.

• The Journal of Internal Korean Medicine
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• v.33 no.4
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• pp.448-464
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• 2012

Objectives : This study reviews the latest articles in Korea and other countries that studied oriental medicine treatment on poststroke depression. Methods : Korean articles were retrieved from the 9 major Korean web article search engines. Foreign articles were retrieved from PubMed. Article published date was from 2000 up to September 2012. There were no restrictions on the types of publication, but articles not available in full text were excluded. The methodological quality was assessed according to Cochrane's assessment of risk of bias and Newcastle-Ottawa quality assessment scale. Results : Twenty-two articles were included in this study. Eleven articles were published in Korea, the rest were published in China. Nine articles were randomized controlled trials (RCT), one article was a non-randomized study (NRS), four articles were case reports, three articles were cross-sectional studies, two articles were comparative studies. In RCT articles, risk of selection bias and performance bias were generally high, risk of detection bias was unclear. The NRS article took four stars in Newcastle-Ottawa quality assessment. Comparison Hamilton rating scale for depression score between oriental medicine treated group and western medicine treated group revealed that there was no remarkable difference in mean score changes after treatment on PSD. Conclusions : The results of this study suggest that oriental medicine treatment is as effective as western medicine treatment for PSD. In the future, more rigorous oriental medicine treatment studies should be conducted.