• Journal of the Korean Society of Radiology
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• v.17 no.4
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• pp.541-549
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• 2023

The aim of this study wasto conduct a quantitative analysis of CT image quality according to an algorithm designed to reduce metal artifacts induced by metal components. Ten baseline images were obtained with the standard filtered back-projection algorithm using spectral detector-based CT and CT ACR 464 phantom, and ten images were also obtained on the identical phantom with the standard filtered back-projection algorithm after inducing metal artifacts. After applying the to raw data from images with metal artifacts, ten additional images for each were obtained by applying the virtual monoenergetic algorithm. Regions of interest were set for polyethylene, bone, acrylic, air, and water located in the CT ACR 464 phantom module 1 to conduct compare the Hounsfield units for each algorithm. The algorithms were individually analyzed using root mean square error, mean absolute error, signal-to-noise ratio, peak signal-to-noise ratio, and structural similarity index to assess the overall image quality. When the Hounsfield units of each algorithm were compared, a significant difference was found between the images with different algorithms (p < .05), and large changes were observed in images using the virtual monoenergetic algorithm in all regions of interest except acrylic. Image quality analysis indices revealed that images with the metal artifact reduction algorithm had the highest resolution, but the structural similarity index was highest for images with the metal artifact reduction algorithm followed by an additional virtual monoenergetic algorithm. In terms of CT images, the metal artifact reduction algorithm was shown to be more effective than the monoenergetic algorithm at reducing metal artifacts, but to obtain quality CT images, it will be important to ascertain the advantages and differences in image qualities of the algorithms, and to apply them effectively.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.86-92
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• 2022

Recently, the bio-healthcare market is enlarging worldwide due to various reasons such as the COVID-19 pandemic. Among them, biometric measurement and analysis technology are expected to bring about future technological innovation and socio-economic ripple effect. Existing systems require a large-capacity battery to drive signal processing, wireless transmission part, and an operating system in the process. However, due to the limitation of the battery capacity, it causes a spatio-temporal limitation on the use of the device. This limitation can act as a cause for the disconnection of data required for the user's health care monitoring, so it is one of the major obstacles of the health care device. In this study, we report the concept of a standalone healthcare monitoring module, which is based on both triboelectric effects and electromagnetic effects, by converting biomechanical energy into suitable electric energy. The proposed system can be operated independently without an external power source. In particular, the wireless foot pressure measurement monitoring system, which is rationally designed triboelectric sensor (TES), can recognize the user's walking habits through foot pressure measurement. By applying the triboelectric effects to the contact-separation behavior that occurs during walking, an effective foot pressure sensor was made, the performance of the sensor was verified through an electrical output signal according to the pressure, and its dynamic behavior is measured through a signal processing circuit using a capacitor. In addition, the biomechanical energy dissipated during walking is harvested as electrical energy by using the electromagnetic induction effect to be used as a power source for wireless transmission and signal processing. Therefore, the proposed system has a great potential to reduce the inconvenience of charging caused by limited battery capacity and to overcome the problem of data disconnection.

• The Korean Journal of Nuclear Medicine
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• v.34 no.1
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• pp.82-93
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• 2000

Purpose: We characterized the signals obtained from the components of a small gamma camera using Nal(Tl)-position sensitive photomultiplier tube (PSPMT) and optimized the parameters employed in the modules of the system. Materials and Methods: The small gamma camera system consists of a Nal(Tl) crystal ($60{\times}60{\times}6mm^3$) coupled with a Hamamatsu R3941 PSPMT, a resister chain circuit, preamplifiers, nuclear instrument modules (NIMs), an analog to digital converter and a personal computer for control and display. The PSPMT was read out using a resistive charge division circuit which multiplexes the 34 cross wire anode channels into 4 signals (X+, X-, Y+, Y -). Those signals were individually amplified by four preamplifiers and then, shaped and amplified by amplifiers. The signals were discriminated and digitized via triggering signal and used to localize the position of an event by applying the Anger logic. The gamma camera control and image display was performed by a program implemented using a graphic software. Results: The characteristics of signal and the parameters employed in each module of the system were presented. The intrinsic sensitivity of the system was approximately $8{\times}10^3$ counts/sec/${\mu}Ci$. The intrinsic energy resolution of the system was 18% FWHM at 140 keV. The spatial resolution obtained using a line-slit mask and $^{99m}Tc$ point source were, respectively, 2.2 and 2.3 mm FWHM in X and Y directions. Breast phantom containing $2{\sim}7mm$ diameter spheres was successfully imaged with a parallel hole collimator. The image displayed accurate size and activity distribution over the imaging field of view Conclusion: We proposed a simple method for development of a small gamma camera and presented the characteristics of the signals from the system and the optimized parameters used in the modules of the small gamma camera.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.96-105
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• 2011

Ubiquitos sensor network(USN) is a technology which is widely used in our life. This paper introduces an example of design and implementation for a system which is based on the USN technology and can provide an efficient management tool for a space that should be precisely controlled for a certain range of uniformity in temperature and humidity. This introduced system builds a wireless sensor network using a number of sensor modules that are equipped with temperature and humidity sensors, and collects temperature and humidity information in real-time while simultaneously providing a method for monitoring the status of temperature and humidity by the graphical user interface. Also, the system will give a warning signal if the monitored values are differ from the pre-specified values of temperature and humidity for each sensor module more than a certain amount of tolerance. This temperature and humidity logging and monitoring system can perform better management for the space easily and efficiently by automating the existing manual method for data collection and management. Furthermore, using the stored data, it can make possible to perform post-analysis on the problems caused by temperature and humidity and to obtain information for environmental enhancement for the space.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.138-143
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• 2016

The designed and fabricated millimeter-wave security screening system receives radiation energy from an object and a human body. The imaging system consist of sixteen array antennas, sixteen four-stage LNAs, sixteen detectors, an infrared camera, a CCD camera, reflector, and a focusing lens. This system requires high sensitivity and wide bandwidth to detect the input thermal noise. The LNA module of the system has been measured to have 65.8 dB in average linear gain and 82 GHz~102 GHz in bandwidth to enhance the sensitivity for thermal noise, and to receive it over a wide bandwidth. The detector is used for direct current (DC) output translation of millimeter-wave signals with a zero bias Schottky diode. The lens and front-end of the millimeter-wave sensor are important in the system to detect the input thermal noise signal. The frequency range in the receiving sensitivity of the detectors was 350 to 400 mV/mW at 0 dBm (1 mW) input power. The developed W-band imaging system is effective for detecting and identifying concealed objects such as metal or plastic.

• Journal of Life Science
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• v.30 no.3
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• pp.304-312
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• 2020

Agarase can be used in the field of basic science, as well as for production of agar-derived high-functional oligosaccharides and bioenergy production using algae. In 2012, we summarized the classification, origin, production, and applications of agar. In this paper, we briefly review the literature on the recombinant expression of agarases from 2012 to the present. Agarase genes originated from 19 genera, including Agarivorans, Flammeovirga, Pseudoalteromonas, Gayadomonas, Catenovulum, Microbulbifer, Cellulophaga, Saccharophagus, Simiduia, and Vibrio. Of the 47 recombinant agarases, there were only two α-agarases, while the rest were β-agarases. All α-agarases produced agarotetraose, while β-agarases yielded many neoagarooligosaccharides ranging from neoagarobiose to neoagarododecaose. The optimum temperature ranged between 25 and 60℃, and the optimum pH ranged from 3.0 to 8.5. There were 14 agarases with an optimum temperature of 50℃ or higher, where agar is in sol state after melting. Artificial mutations, including manipulation of carbohydrate-binding modules (CBM), increased thermostability and simultaneously raised the optimum temperature and activity. Many hosts and secretion signals or riboswitches have been used for recombinant expression. In addition to gene recombination based on the amino acid sequence after agarase purification, recombinant expression of the putative agarase genes after genome sequencing and metagenome-derived agarases have been studied. This study is expected to be actively used in the application fields of agarase and agarase itself.

• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.59-64
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• 2008

D. W. KANG, J. S. CHOI, and G. R. TACK, A Study on Real-Time Sports Activity Classification & Monitoring Using a Tri-axial Accelerometer. Korean Jouranl of Sport Biomechanics, Vol. 18, No. 2, pp. 59-64, 2008. This study was conducted to study the real-time sports activity classification and monitoring using single waist mounted tri-axial accelerometer. This monitoring system detects events of sports activities such as walking, running, cycling, transitions between movements, resting and emergency event of falls. Accelerometer module was developed small and easily attachable on waist using wireless communication system which does not constrain sports activities. The sensor signal was transferred to PC and each movement pattern was classified using the developed algorithm in real-time environment. To evaluate proposed algorithm, experiment was performed with several sports activities such as walking, running, cycling movement for 100sec each and falls, transition movements(sit to stand, lie to stand, stand to sit, lie to sit, stand to lie and sit to lie) for 20 times each with 5 healthy subjects. The results showed that successful detection rate of the system for all activities was 95.4%. In this study, through sports activity monitoring. it was possible to classify accurate sports activities and to notify emergency event such as falls. For further study, the accurate energy consumption algorithm for each sports activity is under development.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.573-582
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• 2010

In this paper, X-band transceiver for high resolution wideband SAR systems is designed and fabricated. Also as a technique for enhancing the performance, error compensation algorithm is presented. The transceiver for SAR system is composed of transmitter, receiver, switch matrix and frequency generator. The receiver especially has 2 channel mono-pulse structure for ground moving target indication. The transceiver is able to provide the deramping signal for high resolution mode and select the receive bandwidth for receiving according to the operation mode. The transceiver had over 300 MHz bandwidth in X-band and 13.3 dBm output power which is appropriate to drive the T/R module. The receiver gain and noise figure was 39 dB and 3.96 dB respectively. The receive dynamic range was 30 dB and amplitude imbalance and phase imbalance of I/Q channel was ${\pm}$0.38 dBm and ${\pm}$3.47 degree respectively. The transceiver meets the required electrical performances through the individual tests. This paper shows the pulse error term depending on SAR performance was analyzed and range IRF was enhanced by applying the compensation technique.

• Korean Journal of Remote Sensing
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• v.31 no.3
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• pp.215-226
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• 2015

Normally, aero photography using UAV uses about 430 MHz bandwidth radio frequency (RF) modem and navigates and remotely controls through the connection between UAV and ground control system. When using the exhausting method, it has communication range of 1-2 km with frequent cross line and since wireless communication sends information using radio wave as a carrier, it has 10 mW of signal strength limitation which gave restraints on life my distance communication. The purpose of research is to use communication technologies such as long-term evolution (LTE) of smart camera, Bluetooth, Wi-Fi and other communication modules and cameras that can transfer data to design and develop automatic shooting system that acquires images to UAV at the necessary locations. We conclude that the android based UAV filming and communication module system can not only film images with just one smart camera but also connects UAV system and ground control system together and also able to obtain real-time 3D location information and 3D position information using UAV system, GPS, a gyroscope, an accelerometer, and magnetic measuring sensor which will allow us to use real-time position of the UAV and correction work through aerial triangulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.42-48
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• 2016

In this paper, a high-precision peak detector circuit that detects the output voltage information of a fly-back converter is proposed. The proposed design consists of basic analog elements with only one operational amplifier and three transistors. Because of its simple structure, the proposed circuit can minimize the delay time of the detection process, which has a strong impact on the precision of the regulation aspect of the fly-back converter. Furthermore, by using an amplifier and several transistors, the proposed detector can be fully integrated on-chip, instead of using discrete circuit elements, such as capacitors and diodes, as in conventional designs, which reduces the production cost of the fly-back converter module. In order to verify the performance of the proposed scheme, the peak detector was simulated and implemented by using a 0.35 m MagnaChip process. The gained results from the simulation with a sinusoidal stimulus signal show a very small detection error in the range of 0.3~3.1%, which is much lower than other reported detecting circuits. The measured results from the fabricated chip confirm the simulation results. As a result, the proposed peak detector is recommended for designs of high-performance fly-back converters in order to improve the poor regulation aspect seen in conventional designs.