• Smart Media Journal
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• v.12 no.10
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• pp.93-101
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• 2023

Climate change has emerged as a global problem, with frequent temperature increases, droughts, and floods, and it is predicted that it will have a great impact on the characteristics and productivity of crops. Cnidium officinale is used not only as traditionally used herbal medicines, but also as various industrial raw materials such as health functional foods, natural medicines, and living materials, but productivity is decreasing due to threats such as continuous crop damage and climate change. Therefore, this paper proposes a model that can predict the physiologically active ingredient index according to the climate change scenario of Cnidium officinale, a representative medicinal crop vulnerable to climate change. In this paper, data was first augmented using the CTGAN algorithm to solve the problem of data imbalance in the collection of environment information, physiological reactions, and physiological active ingredient information. Column Shape and Column Pair Trends were used to measure augmented data quality, and overall quality of 88% was achieved on average. In addition, five models RF, SVR, XGBoost, AdaBoost, and LightBGM were used to predict phenol and flavonoid content by dividing them into ground and underground using augmented data. As a result of model evaluation, the XGBoost model showed the best performance in predicting the physiological active ingredients of the sacrum, and it was confirmed to be about twice as accurate as the SVR model.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.113-118
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• 2013

In this paper, spoofing effects on a GNSS receiver were analyzed. The spoofer (spoofing device) was classified to two categories. One is an active spoofer and the other is a passive spoofer. The active spoofer was considered for analysis. For the analysis of spoofing effects on a GNSS receiver, a real-time GNSS spoofing simulator was developed. The simulator was consisted with two parts which are a baseband signal generation part and a RF up-conversion part. The first GNSS baseband signal was generated according to spoofing parameters such as range, range rate, GNSS navigation data, spoofing to GNSS signal ratio, and etc. The generated baseband signal was up-converted to GNSS L1 band. Then the signal transmitted to a GNSS signal. For a perfect spoofing, a spoofer knew an accurate position and velocity of a spoofing target. But, in real world, that is not nearly possible. Although uncertainty of position and velocity of the target was existed, the spoofer was operated as an efficient jammer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.339-346
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• 1999

A RF receiver section for INMARSAT-C external mounting unit was designed, fabricated and evaluated. Using a INA-03184, the high gain amplifier consists of matched amplifier type. Active bias circuitry can be used to provide temperature stability without requiring the large voltage drop or relatively high-dissipated power needed with a bias stabilization resistor. The bandpass filter was used to reduce a spurious level. As a result, the characteristics of the receiver section implemented here show 60 dB in gain, 44.83 dBc in a spurious level. The voltage standing wave ratios(VSWR)of input output port are less than 1.8:1, respectively.

• Microbiology and Biotechnology Letters
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• v.25 no.4
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• pp.391-395
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• 1997

It was proved that both ethanol extracts from Mori Folium from Kangwon do and silk worm had higher inhibition acitivity on $\alpha$-glucohydrolase than the water extracts. In adding above 8.5 (mg/L) of silkworm extracts, the inhibition rate on $\alpha$-1,4 glucosidase was saturated while the inhibition rate was continuously increased in adding the extracts from Moli Folium. It was also found that the diethyl ether fraction showed much better inhibition activity than water fraction from ethanol extracts, yielding ca. 85% of inhibition rate for the extract of Moli Folium, compared to 91% for a commercially available hypoglycemic drug, Chloropropamide. In separating the diethyl ether fractions by Consecutive Sephadex gel filtration and Thin layer chromatography, three and four active spots were obtained from Moli Folium and silkworm, respectively. It is interesting that the similar Rf spots from both species among several spots in TLC have the highest inhibition acitivity on a target enzyme, which can imply that the active substances from both species are same or similar molecular weight and structure. Glucose-lowering activities of both speciese were also examined in vivo, showing that the fraction from Moli Folium had better activity than that from silkworm, and its activity was similar to that of a commercial drug.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1137-1140
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• 2011

In this paper, the optimal condition for efficient active frequency multipliers is analyzed. This analysis is based on the effects from transistor nonlinear coefficients, harmonic impedances, and output parasitic components. From the analysis, normalized harmonic power is estimated with the clipping condition of a commercial transistor, and the condition for high conversion efficiency is suggested. From the analysis, a class-F frequency tripler was implemented for the output at 2.475 GHz, showing the maximum efficiency of 22.9 % and the maximum conversion gain of 9.5 dB.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.711-717
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• 2007

Location information will become increasingly important for future Pervasive Computing applications. Location tracking system of a moving device can be classified into two types of architectures: an active mobile architecture and a passive mobile architecture. In the former, a mobile device actively transmits signals for estimating distances to listeners. In the latter, a mobile device listens signals from beacons passively. Although the passive architecture such as Cricket location system is inexpensive, easy to set up, and safe, it is less precise than the active one. In this paper, we present a passive location system using Cricket Mote sensors which use RF and ultrasonic signals to estimate distances. In order to improve accuracy of the passive system, the transmission speed of ultrasound was compensated according to air temperature at the moment. Upper and lower bounds of a distance estimation were set up through measuring minimum and maximum distances that ultrasonic signal can reach to. Distance estimations beyond the upper and the lower bounds were filtered off as errors in our scheme. With collecting distance estimation data at various locations and comparing each distance estimation with real distance respectively, we proposed an equation to compensate the deviation at each point. Equations for proposed algorithm were derived to calculate relative coordinates of a moving device. At indoor and outdoor tests, average location error and average location tracking period were 3.5 cm and 0.5 second, respectively, which outperformed Cricket location system of MIT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.689-692
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• 2005

In this paper, we have developed a retrodirective active array operating in the 2 GHz LS band. The retrodirective array has the property of re-directing any electromagnetic wave back to the incoming direction without any priory informations. The system is consisted of frequency mixers and antenna array. The mixer is acting as a phase conjugator. In this research, 2-port gate mixers using pHEMT and 1${\times}$4 monopole array have been used. The retrodirective array developed in this research can be applied in the base station facilities for the wireless mobile communications and RFID transponders.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.61-64
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• 2017

A phase shifter is one of the key components that change the phase of an individual antenna in millimeter-wave phased array system. This paper presents a low-loss phase shifter design with two parallel 2-state amplifiers. To get the same gain of $0^{\circ}/180^{\circ}$ each state, delay lines are in the middle of each stage of the 2-Stage amplifiers. Normally, when adding AMPs in parallel, a power combiner/divider such as Wilkinson Power Combiner/Divider is added, but they are directly connected because it can cause added losses in silicon wafer. The measured data shows 12dB gain and 174-degree phase difference at 5GHz.

• 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.

• Korean Journal of Materials Research
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• v.9 no.1
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• pp.14-17
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• 1999

Tin oxide films as an anode layer for microbatteries were deposited by using rf magnetron sputtering. Characterization of the films was carried out in terms of working pressure in the range of 5~30 mtorr. Rf power and substrate temperature during deposition were fixed at 2.5W/$\textrm{cm}^2$ and A.T., respectively. The crystal orientation of $SnO_2$films was changed from (110) to (101) or (211) with the increasing working pressure. Refractive index and film density of the films also decreased with the increasing working pressure. The $SnO_2$ thin film formed under optimum conditions was found to have a reversible capacity of 446.9$\mu$Ah/$\textrm{cm}^2$-$\mu\textrm{m}$ and good reversibility when the working pressure was fixed at 10mtorr. As the working pressure decreased, film density increased. It was thought that the capacity of $SnO_2$films increased due to the increase in the amount of active materials which can react with Li electrochemically. Furthermore, cycle characteristics of the anode material was also influenced by film stress.