• Journal of Advanced Navigation Technology
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• v.24 no.4
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• pp.299-304
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• 2020

This paper proposes the design of circular sector shaped power divider-combiner with a planar structure. This structure can be constructed in series, and due to the circular sector shape, it is possible to simplify circuit configuration and improve the amplitude and phase balanced characteristics of the output. It has a simple input matching circuit and an RC parallel circuit was inserted between the output ports to improve the reflection coefficient and isolation of the output. Since the designed divider-combiner are structurally designed in a symmetrical shape of a sector, even if the output ports are composed of two or four output ports, they have excellent characteristics with an amplitude balance of ± 0.1 dB and a phase balance of ± 1o between outputs. To prove these characteristics, it was confirmed that the characteristics of the planar power divider-combiner fabricated at an operating frequency of 2 GHz are in good agreement with the simulation.

• Journal of Korea Trade
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• v.25 no.1
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• pp.89-111
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• 2021

Purpose - The U.S. Trade Preference Expansion Act (TPEA) of 2015 enables the US Department of Commerce (DOC) to inflate dumping margin when the particular market situation (PMS) exists in the exporter's home market. DOC applied PMS provisions to the steel products from Korea. This paper analyzes whether DOC's calculation by using the regression analysis is consistent with WTO rules. Design/methodology - This paper analyzes the PMS application in law and regression analysis that extends the data period from 10 years to 18 years using the same economic model with DOC, and changes the country group according to the quantities of steelmaking capacity. Findings - Results show that DOC's argument conflating the sales-based with cost-based PMS designed to inflate dumping margins might not be consistent with WTO Antidumping Agreement Article 2.2 and 2.2.1.1 in which costs shall normally be calculated on the basis of records kept by the exporter, providing generally accepted accounting principles and reasonably reflection of the costs and PMS that exists in the Korean steel product markets. Even if it will be consistent, DOC's calculated margin by the regression analysis using a 10-year data is a big gap (5 times) compared with an 18-year data projection and different countries' data through the same methodology, which is a huge gap of regression coefficient. It means that dumping margin would be very wide range from 7.8% to 38.54% and unstable to calculate. Inflating dumping margin by DOC using regression analysis would not only be inconsistent with WTO rules, but also projection result is unreliable. Originality/value - Literature papers have mainly analyzed WTO law itself. This paper however, would be the first attempt to analyze the DOC's new way of dumping margin calculation in both manners of law and an empirical methodology perspective at the same time.

• 한국노년학
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• v.30 no.1
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• pp.65-80
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• 2010

Purpose: The purpose of this study was to develop a wisdom scale among Korean elderly with high validity and reliability. Method: The process of the development of this scale follows: A conceptual framework was identified based on literature a review of the elderly and discussion with experts in physiology and sociology. Total 128 items were developed. Through reliability testing, factor analysis, 60 preliminary items, and 4-points scale were selected. By a means of the internal consistency for 60 items, 33 items were deleted. Finally, 27 items were remained. To verity 27 items, factor analysis, reliability testing, and correlation were done. Data were collected from 480 elderly subjects in Daegu, Kyungpook Province, and Busan, Kyungnam Province from August, 2008 to February, 2009. Results: From the results of the factor analysis for 27 items, 3 factors were extracted. These factors were labeled as 'empathic emotion', 'self-reflection', and 'bitter experience of life'. Cronbach's Alpha for the 27 items was .921 and correlation coefficient of ego-integrity was .69. Conclusion: An exploratory study of the variables related to wisdom among the elderly is needed for criterion validity of this scale. A study on wisdom for different age groups is needed for re-verification.

• The Journal of Korean Institute of Information Technology
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• v.16 no.11
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• pp.77-84
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• 2018

In this paper, the circular polarization microstrip patch antenna using the T-junction power divider is proposed. The operating frequency of the proposed antenna is ISM band of 2.4GHz and the circular polarization is induced by feeding a phase difference of $90^{\circ}$ in two edges. The structure of the antenna consists of a general patch and a T-junction power divider. Furthermore, to optimize the proposed antenna, it is analyzed the reflection coefficient, the axial ration and the radiation pattern. The impedance bandwidth of the antenna is observed to be 40MHz within a range of 2.39 to 2.43GHz, similarly, the axial ratio bandwidth is observed having the bandwidth of about 12MHz in 2.398 to 2.410GHz range. The radiation pattern of the antenna is seen to be right circular polarization. Furthermore, the gain of the antenna is observed to be 2.04 and 3.4dBic at XZ and YZ-plane, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.6
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• pp.445-451
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• 2019

This paper presents the design of a water-cooled radio-frequency(RF) load with simple structure, for use in the ultrahigh-frequency (UHF) band. After establishing a formula to obtain the physical properties that affect RF matching, we measure the permittivity and $tan{\delta}$(Loss tangent) of tap water. Because the temperature of tap water increases upon applying high power, we measure the permittivity and $tan{\delta}$ for all changes in the temperature of tap water. In order to reduce the length of the water-load, molybdate with high $tan{\delta}$ is mixed with tap water. The loss tangent of the mixture is found to be approximately 26 times higher than that of tap water. Finally, we manufacture a water-cooled RF load and measure its characteristics. A reflection coefficient of -19 dB and bandwidth of 15 % is obtained at 460 MHz.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.61-62
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• 2016

In this paper, a design method for a compact stepped open slot antenna for an operation in the UWB band is studied. The proposed antenna is miniaturized by inserting L-shaped slots on the ground plane of the stepped open slot antenna through the creation of a resonance in the low frequency, and a strip director is appended to the antenna in order to increase the gain in the middle and high frequency regions. The effects of varying the length of the L-shaped slots, the distance between the director and the slot antenna, and the director length on input reflection coefficient and realized gain characteristics of the proposed antenna are analyzed. The optimized antenna with the size of $30mm{\times}30mm$ is fabricated on an FR4 substrate, and the experiment results show that the antenna has a frequency band of 3.02-11.04 GHz for a VSWR < 2, which assures the operation in the UWB band.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.157-158
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• 2014

In this paper, a design method for a compact CPW-fed slot antenna using SRRs(split-ring resonators) is studied. The structure of the proposed slot antenna is a rectangular slot antenna loaded with SRR conductors inside the slot to reduce the antenna size. Optimal design parameters are obtained by analyzing the effects of the gap between the SRR conductors and slot, and the width of the SRR conductors on the input reflection coefficient characteristic. The optimized compact slot antenna operating at 2.45 GHz band is fabricated on an FR4 substrate with a dimension of 36 mm by 30 mm. The length of the proposed compact slot antenna is reduced by 14.3% compared to that of a conventional rectangular slot antenna. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.4-2.49 GHz for a VSWR < 2.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.959-965
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• 2019

In this paper, we design a low noise amplifier to support ka-band satellite communication systems using 65-nm RFCMOS process. The proposed low noise amplifier is designed with high-gain mode and low-gain mode, and is designed to control the gain according to the magnitude of the input signal. In order to reduce the power consumption, the supply voltage of the entire circuit is limited to 1 V or less. We proposed the gain control circuit that consists of the inverter structure. The 3D EM simulator is used to reduce the size of the circuit. The size of the designed amplifier including pad is $0.33mm^2$. The fabricated amplifier has a -7 dB gain control range in 3 dB bandwidth and the reflection coefficient is less than -6 dB in high gain mode and less than -15 dB in low gain mode.

• Journal of Advanced Navigation Technology
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• v.23 no.4
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• pp.309-315
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• 2019

This paper proposes an implementation of unequal power divider with 1:3 and 1:4 splitting ratio in multi-section structure using CPW and offset coupled transmission line. The power divider consists of a multi-section transmission line and a circuit with parallel capacitors and resistors. A multi-section transmission line was implemented by decomposing a ${\lambda}/4$ single transmission line terminated by an arbitrary impedance and converging it with a multi-section transmission line shorter than $90^{\circ}$ electrical length, and RC parallel circuits were connected between transmission lines to obtain reflection coefficient of output port and isolation characteristics between the output port. In this way, it was confirmed that the transmission lines at the unequal power divider designed at 2 GHz were shorter than ${\lambda}/4$ and implemented at least 27% less than the conventional ones, and that the broadband characteristics could be obtained.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.995-1010
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• 2020

In this study, a multivariate analysis model of partial least square regression (PLSR) was developed to predict the moisture content of green peppers using hyperspectral imaging (HSI). In HSI, illumination is essential for high-quality image acquisition and directly affects the analytical performance of the visible near-infrared hyperspectral imaging (VIS/NIR-HSI) system. When green pepper images were acquired using a direct lighting system, the specular reflection from the surface of the objects and their intensities fluctuated with time. The images include artifacts on the surface of the materials, thereby increasing the variability of data and affecting the obtained accuracy by generating false-positive results. Therefore, images without glare on the surface of the green peppers were created using a polarization filter at the front of the camera lens and by exposing the polarizer sheet at the front of the lighting systems simultaneously. The results obtained from the PLSR analysis yielded a high determination coefficient of 0.89 value. The regression coefficients yielded by the best PLSR model were further developed for moisture content mapping in green peppers based on the selected wavelengths. Accordingly, the polarization filter helped achieve an uniform illumination and the removal of gloss and artifact glare from the green pepper images. These results demonstrate that the HSI technique with a polarized lighting system combined with chemometrics can be effectively used for high-throughput prediction of moisture content and image-based visualization.