• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.862-865
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• 2008

Wireless energy supply for an MAV propulsion system using microwave was developed. This system consists of three sub system; the transmitter system, the rectenna system, and the tracking system. In the transmitter system five horn antennas were used as the antenna elements for the phased array system and both the beam divergence and steering angle was about 9deg. Eight rectennas were arrayed in parallel to obtain enough power to drive the electric motor on the MAV(the voltage was 250mV and the current was 6.8mA) in rectenna system. In tracking system two units of antenna system with leaf pattern which received the linearly-polarized wave despite the MAV yaw angle were set in each axis(x, y) for tracking an MAV in a 2-Dimentional space. And three output voltages $V_{com},\;V_1$ and $V_2$ were loaded in the PC to detect if the distance between transmitter and receiver was not constant. Finally when the microwave beam was steered by the phased array system the output voltage from rectenna was measured at 62cm while the MAV circled around above the transmitter system.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.68-73
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• 2006

The present paper deals with an experimental study of boiling heat transfer characteristics of R-290, and is focused on pressure gradient and heat transfer coefficient of the refrigerant flow inside horizontal smooth minichannel with inner diameter of 3.0 mm and length of 2000 mm. The direct heating method applied for supplying heat to the refrigerant where the test tube was uniformly heated by electric current which was applied to the tube wall. The experiments were conducted with R-290 with purity of 99.99% at saturation temperature of 0 to $10^{\circ}C$. The range of mass flux is $50{\sim}250kg/m^2s$ and heat flux is $5{\sim}20kW/m^2$. The heat transfer coefficients of R-290 increases with increasing mass flux and saturation temperature, wherein the effect of mass flux is higher than that of the saturation temperature, whereas the heat flux has a low effect on increasing heat transfer coefficient. The significant effect of mass flux on heat transfer coefficient is shown at high quality, the effect of heat flux on heat transfer coefficient at low quality shows a domination of nucleate boiling contribution. The heat transfer coefficient of the experimental result was compared with six existing heat transfer coefficient correlation. Zang et al.'s correlation(2004) gave the best prediction of heat transfer coefficient.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.473-478
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• 2011

A wide diversity of liquid fertilizers and composts produced from the livestock manure in Korea is commonly applied to agricultural lands as an alternative of chemical fertilizers. However, their effects on the crop production and environmental impacts are still vague. The current study was conducted to understand the effects of the pig manure-based liquid fertilizer on the growth of Zea mays L. and soil properties. Four different liquid fertilizers were treated to each cultivated upland plot located in Gyeong-gi province, Korea while no fertilizer (control A) and a chemical fertilizer (control B) were treated to separate plots for comparison. The liquid fertilizer treatment did not make a significant difference in the fresh weight of Zea mays L. compared to the controls. This is probably due to the nutrient residues carried over from the last year fertilization. Electric conductivity (EC) and organic matter contents in soils were increased right after the liquid fertilizer treatments compared to the controls. However, soil pH was maintained as the same as the level of control A. A long-term effect of the continuous treatment of the manure based liquid fertilizer will be carried out in the successive study.

• Korean Journal of Psychosomatic Medicine
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• v.24 no.1
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• pp.61-65
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• 2016

Currently, a variety of Information and Communication Technology(ICT) is being broadly utilized for mental health. Especially, mobile application is one of the effective ICT, and several applications have been developed after the spread of smartphones. The mobile-based mental health has several strengths, such as better treatment accessibility and easier check-ups of symptoms or daily activities by real-time monitoring. Better follow-ups of treatment course, more customized feedback and better transportability enable patients to be more adherent. However, there are some limitations of mobile technology about the mental health, such as technical troubles of electric errors, data safety problems and personal information extrusion. Therefore, full considerations should be given during the development and provision of the technology. Most of all, mental health specialists should actively participate in the development process by incorporation of evidence-based experiences and assurance of good clinical qualities.

• Journal of the Korea Convergence Society
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• v.9 no.12
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• pp.373-380
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• 2018

This study classified hairdressing techniques into hairdressing equipment, beauty/care, and styling and investigated current trends in patent applications. In addition, it analyzed what aspects should be concentrated on in terms of future hairdressing techniques and their growth potential. The results found the following: Hairdressing techniques have been on the rise since 1990 in terms of patent activities. In particular, they have been most active in 'electric hairdressing equipment such as hair dryers and hair straighteners. According to analysis of applicants' application trends, technique leaders were different by sector. In hairdressing techniques, in other words, expertise should be developed by sector. It is anticipated that this study would facilitate and expand the hairdressing market by analyzing hairdressing technique patent trends and establishing future directions for R&D in hairdressing techniques.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.472-478
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• 2019

A stable desalination method of the hardness substance such as $Ca^{2+}$ by controlling the total charge (TC) supplied to the membrane capacitive deionization (MCDI) cell was studied. The adsorption (1.5 V) and desorption (0.0 V) were repeated 30 times while varying the TC in the adsorption process. The concentration and pH of effluent, adsorption and desorption amounts, current densities and cell potentials were analyzed in the desalination process. The maximum allowable charge (MAC) of the carbon electrode used in MCDI cell was measured to be 46 C/g. As a result of operation at TC (40 C/g) below the MAC value, electrode reactions did not occur, resulted in the stable desalination characteristics for a long-term operation. When operating at TCs (50, 60 C/g) above the MAC value, however, the concentration and pH of effluent varied greatly. Also, the scale was formed on the electrode surface due to electrode reactions, and the electric resistance of the cell gradually increased. It was thus concluded that it is possible to remove stably the hardness substance without any electrode reactions by controlling the charge supplied to MCDI cell during the adsorption process.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.545-550
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• 2018

Ministry of Oceans and Fisheries declared action plan for the electric fishing gear using real name in order to prevent overusing the fishing gear and to reduce discarded fishing gear. It is needed for a technique that can efficiently transmit the information including the type and location of the fishing gear and the user's real name to the fishing boat and the control center using IoT-based communication. The marine tracker buoy system, which is placed on the water for a long time, transmit the position data and the state data of the buoys to the control center in the ground by using NB-IoT channels. In this paper, we propose the algorithm for the low-power operation of the marine tracker buoy system is proposed and test results of current consumption in the marine tracker buoy system with the proposed algorithm is investigated.

• Journal of Powder Materials
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• v.26 no.2
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• pp.132-137
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• 2019

Tungsten carbide (WC) hard materials are used in various industries and possess a superior hardness compared to other hard materials. They have particularly high melting points, high strength, and abrasion resistance. Accordingly, tungsten carbide hard materials are used for wear-resistant tools, cutting tools, machining tools, and other tooling materials. In this study, the WC-5wt.%Co, Fe, Ni hard materials are densified using the horizontal ball milled WC-Co, WC-Fe, and WC-Ni powders by a spark plasma sintering process. The WC-5Co, WC-5Fe, and WC-5Ni hard materials are almost completely densified with a relative density of up to 99.6% after simultaneous application of a pressure of 60 MPa and an electric current for about 15 min without any significant change in the grain size. The average grain size of WC-5Co, WC-5Fe, and WC-5Ni that was produced through SPS was about 0.421, 0.779, and $0.429{\mu}m$, respectively. The hardness and fracture toughness of the dense WC-5Co, WC-5Fe, WC-5Ni hard materials were also investigated.

• Journal of IKEEE
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• v.23 no.3
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• pp.947-953
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• 2019

The purpose of this paper is to explore an ASIC design for estimating sizes and concentrations of airborne micro-particles by the means of integrating, amplifying and digitizing electric charge signals generated by photo-sensors as it receives scattered photons by the presence of micro-particles, consisting of a pre-amplifier that detects and amplifies voltage or current signal from photo-sensor that generates charges (hole-electron pairs) when exposed to visible rays, infrared rays, ultraviolet rays, etc. according to the intensity of rays; a shaper for shaping the amplified signal to a semi-gaussian waveform; two discriminators and binary counters for outputting digital signals by comparing the magnitude of the shaped signal with an arbitrary reference voltages. The ASIC with the proposed architecture and functional blocks in this study was designed with a 0.18um standard CMOS technology from Global Foundries and the operation and performances of the ASIC has been verified by the silicons fabricated by using the process.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.113-118
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• 2019

A solar power plant is a facility that produces electricity. As the risk of fire and electric shock accidents is diversified, the risk of workers, surrounding people, and facilities is increased, preventing safety accidents and promptly responding to safety accidents Is emerging. In light of the necessity of such development, it is necessary to develop a solar power generation management system that can diagnose and maintain the problems of the power generation system in real time by developing technologies for collecting and analyzing the data produced by the solar power generation system As a result, the utilization rate and the maintenance cost can be reduced. In order to do this, it is necessary to accurately predict the solar power generation amount in the present state, to diagnose the abnormality of the current power generation state and to grasp the abnormal position, and to use the model considering economical efficiency when the abnormal position is grasped, And the time and other information should be provided.