• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.82-89
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• 2014

Recently, inertial sensors are popularly used for the location and position recognition of small devices for M2M/IoT. In this paper, we designed low power, low noise, small sized 6-axis inertial sensor IC for mobile applications, which uses a 3-axis piezo-electric gyroscope sensor and a 3-axis piezo-resistive accelerometer sensor. Proposed IC is composed of 3-axis gyroscope readout circuit, two gyroscope sensor driving circuits, 3-axis accelerometer readout circuit, 16bit sigma-delta ADC, digital filter and control circuit and memory. TSMC $0.18{\mu}m$ mixed signal CMOS process was used. Proposed IC reduces 27% of the current consumption of LSM330.

• 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.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.43-53
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• 2015

This study analyzes economic feasibility of the LED lighting system compare to the halogen. To evaluate economic feasibility of the LED devices, we analyzed the size of theater, current value of the lighting devices in kinds, annual cost and annual cost according to the surface in case of designing stage lighting system with LED using WEELS 2011. Also, to compare energy consumption, we analyzed consumption and amount of electric energy by the surface and the amount of CO2 emission. Data showed that annual cost of the LED devices are highly inexpensive than halogen and now the value is of great. However initial cost of the equipment 200% higher than halogen. Though LED devices are expensive in startup setting, the value of utilization factor is large and depreciation years of LED(30years) are longer than halogen(2years). Therefore, annual cost of LED can make up the minus. Consider the tendency of reducing price of LED devices, we can assume that annual cost of the LED will be lower than halogen devices. Further, in 3years the expense of LED and halogen is reversed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.1
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• pp.65-75
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• 2011

Power Line Communication (PLC) is a system for carrying data on a conductor used for electric power transmission. Recently, PLC has received much attention due to connection efficiency and possibility of extension. It can be used for not only alternative communication, in which communication line is not sufficient, but also for communication between home appliances. Korea Electronic Power Cooperation (KEPCO) is constructing the system, which automatically collects values of power consumption of every household. Due to the randomness and complicated physical characteristics of PLC protocol (KS X4600-1), it has been believed that the current PLC is secure in the sense that it is hard that an attacker guesses or modifies the value of power consumption. However, we show that the randomness of the protocol is closely related to state of the communication line and thus anyone can easily guess the randomness by checking the state of the communication line. In order to analyze the security of PLC, we study the protocol in detail and show some vulnerability. In addition, we suggest that PLC needs more secure protocol on higher layers. We expect that the study of PLC help in designing more secure protocol as well.

• Journal of Environmental Science International
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• v.20 no.10
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• pp.1273-1284
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• 2011

The aim of this research was to evaluate the performance of insoluble electrode for the purpose of degradation of Rhodamine B (RhB) and oxidants generation [N,N-Dimethyl-4-nitrosoaniline (RNO, indicator of OH radical), $O_3$, $H_2O_2$, free Cl, $ClO_2$)]. Methods: Four kinds of electrodes were used for comparison: DSA (dimensional stable anode; Pt and JP202 electrode), Pb and boron doping diamond (BDD) electrode. The effect of applied current (0.5~2.5 A), electrolyte type (NaCl, KCl and $Na_2SO_4$) and electrolyte concentration (0.5~3.5 g/L) on the RNO degradation were evaluated. Experimental results showed that the order of RhB removal efficiency lie in: JP202 > Pb > BDD ${\fallingdotseq}$ > Pt. However, when concerned the electric power on maintaining current of 1 A during electrolysis reaction, the order of RhB removal efficiency was changed: JP202 > Pt ${\fallingdotseq}$ Pb > BDD. The total generated oxidants ($H_2O_2$, $O_3$, free Cl, $ClO_2$) concentration of 4 electrodes was Pt (6.04 mg/W) > JP202 (4.81 mg/W) > Pb (3.61 mg/W) > BDD (1.54 mg/W), respectively. JP202 electrode was the best electrode among 4 electrodes from the point of view of performance and energy consumption. Regardless of the type of electrode, RNO removal of NaCl and KCl (chlorine type electrolyte) were higher than that of the $Na_2SO_4$ (sulfuric type electrolyte) RNO removal. Except BDD electrode, RhB degradation and creation tendency of oxidants such as $H_2O_2$, $O_3$, free Cl and $ClO_2$, found that do not match. RNO degradation tendency were considered a simple way to decide the method which is simple it will be able to determinate the electrode where the organic matter decomposition performance is superior. As the added NaCl concentration was increases, the of hydrogen peroxide and ozone concentration increases, and this was thought to increase the quantity of OH radical.

• Journal of the Korean Electrochemical Society
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• v.17 no.1
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• pp.37-43
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• 2014

In this study, capacitive deionization (CDI) was introduced for desalination of mining water. Ion-exchange polymer coated carbon electrodes (IEE) were used in CDI to desalt mining water. The CDI performance using the IEE for desalination of mining water was carried out and then was compared with that using general carbon electrodes without ion-exchange polymer coating (GE). Moreover, to investigate the effect of the concentration of influent solutions on CDI performance, the CDI performance using the IEE for desalination of brackish water (NaCl 200 ppm) was also performed and analyzed. As a result, the higher salt removal efficiency, rate and the lower energy consumption in the CDI process using the IEE and mining water were obtained compared with those using the GE and mining water. It is mainly due to higher non-Faradaic current, low ohmic resistance of the influent, overlapping effect of electric double layers in micropore of the electrode. In addition, the CDI process using the IEE and brackish water shows much higher salt removal efficiency and lower salt removal rate than that using the IEE and mining water. This results from the lower concentration (i.e., higher ohmic resistance) and salt amount of the influent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.618-624
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• 2020

A portable power supply system for soldiers must be able to supply electric energy corresponding to the power consumption of combat support troops, and have a carrying load in a range that does not impair the combatant's ability to execute operations. In particular, as the total required power of combat equipment increases with the advances in the future soldier system, a portable, lightweight power supply system with high efficiency is essential. A fuel cell has a high energy-to-weight density compared to lithium batteries, which are used mainly as a military power source system. Therefore, it is capable of miniaturization and lightweight, making active R&D to a portable power supply system. In this paper, the characteristics of the fuel cell applied as a portable power supply system, and the R&D trends of domestic and foreign military portable fuel cell systems were investigated. The current status of domestic technology compared to the level of foreign development was analyzed. In addition, future technology development plans are presented based on the consideration factors when developing a portable fuel cell (power supply stability, portability, and cost reduction) so that it can be used when establishing a plan on the development of a portable fuel cell system for the future soldier system.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.8
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• pp.411-419
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• 2016

The objective of this study was to evaluate the application possibility of tube type electrolysis module system using recirculation process through removal organic matters and nitrogen in the pigment wastewater. The tube type electrolysis module consisted of a inner rod anode and an outer tube cathode. Material used for anode was titanium electroplated with $RuO_2$. Stainless steel was used for cathode. It was observed that the pollutant removal efficiency was increased according to the decrease of flowrate and increase of current density. When the retention time in tube type electrolysis module system was 180 min, chlorate concentration was 382.4~519.6 mg/L. The chlorate production was one of the major factors in electrochemical oxidation of tube type electrolysis module system using recirculation process used in this research. The pollutant removal efficiencies from the bench scale tube type electrolysis module system using recirculation operated under the electric charge of $4,500C/dm^2$ showed the $COD_{Mn}$ 89.6%, $COD_{Cr}$ 67.8%, T-N 96.8%, and Color 74.2%, respectively and energy consumption was $5.18kWh/m^3$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.715-721
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• 2018

This study examined energy saving and elevating the worker's neuro energy (comfort, concentration, physical, and psychological stability) by compensating for the unpleasant tactile sensation to stimulate auditory and olfactory senses and reduce energy consumption. The experiment was conducted in an environment test room under the test conditions of temperature $25[^{\circ}C]$, relative humidity 50[RH%], illumination 1,000[lux] and air current speed 0.02[m/sec] by stimulating the auditory senses with a 1/f change in rhythm and the olfactory senses with an aroma scent. The experiment utilized the method of EEG, which evaluates human body's psychological status via tactile means, and the method of the vibra image, which evaluates the learning abilities, HRV and human body's psychological status via non-tactile means. The subjects were selected as eight university students (four males and four females) in their 20s, the type that have high relative ${\alpha}$(8~13[Hz]) activation in occipital lobe, which brings the highest level of mind stability and concentration, who had no difficulty in physical activities. The subjects' posture and physical activity was fixed to 1met - when the subjects are seated and relaxing in a comfortable environment - and their clothes condition was standardized as 0.7clo. As a result, the sentimental and psychological stability and concentration were the highest in the multisensory stimulation of jasmine scent and change rhythm of an a=1.106 sound source. In addition, under this condition, the relative $M{\alpha}$ and relative $M{\beta}$ increased by 70.49[%] and 89.72[%], respectively; the HRT decreased by 39.09[%]; and the fatigue and tension/anxiety decreased by 36.85[%] and 15.54[%], respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.1003-1013
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• 2006

There is a serious problem in an 802.11g VoWLAN (Voice over Wireless LAN) terminal that talk time is less than 30% compared with an 802.11b terminal. It is almost impossible to achieve talk time level of the 802.11b MAC transmission method because IEEE 802.11g uses OFDM modulation, which is a kind of multi-carrier method and OFDM transmission speed is 54 Mbps faster than normal modulation. In this paper, a new concept of a Holdover time as a power saving method during a call with 802.11g terminal is suggested for the first time. Increase in the number of engaged terminals as a result of holdover time causes to QoS problem because of the increase in the number of back-off and then contention window. In this paper, to solve the QoS problem, a new approach is suggested such that when in down lint the sequence number of 802.11 G.711 is analyzed in the MAC of the terminal and then the Hold over time depending on loss rate is changed. Also, consumption of an electric current of 802.11b/g and MAC parameter's performance due to busy traffic caused by increase in the number of terminal are analyzed and then real data using VQT and Airopeek are analyzed.