• Journal of Energy Engineering
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• v.12 no.1
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• pp.1-10
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• 2003

Pressurized fluidized bed combustion unit is operated at pressures of 1~1.5 MPa with combustion temperatures of 850~87$0^{\circ}C$. The pressurized coal combustion system heats steam, in conventional heat transfer tubing, and produces a hot gas supplied to a gas turbine. Gas cleaning is a vital aspect of the system, as is the ability of the turbine to cope with some residual solids. The need to pressurize the feed coal, limestone and combustion air, and to depressurize the flue gases and the ash removal system introduces some significant operating complications. The proportion of power coming from the steam : gas turbines is approximately 80:20%. Pressurized fluidized bed combustion and generation by the combined cycle route involves unique control considerations, as the combustor and gas turbine have to be properly matched through the whole operating range. The gas turbines are rather special, in that the maximum gas temperature available from the FBC is limited by ash fusion characteristics. As no ash softening should take place, the maximum gas temperature is around 90$0^{\circ}C$. As a result a high pressure ratio gas turbine with compression intercooling is used. This is to offset the effects of the relatively low temperature at the turbine inlet.

• Journal of Korean Society of Disaster and Security
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• v.5 no.2
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• pp.81-87
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• 2012

Critical infrastructures (energy, information technology and communications, banking, transportation, public government services, etc.) are now more vital to modern society. Citizens, businesses and governments all rely on an array of interlinked physical and information infrastructures to satisfy their needs and perform their daily operations. At the same time, these infrastructures are becoming increasingly interdependent, such that failure of one of them can often propagate and result in domino effects. Recent dramatic episodes, from 9/11 to the Madrid train bombings, the April 2010 ash cloud the power cuts in Korea in 2011, and the cyber-attacks have highlighted the need for a comprehensive, internationally coordinated policy for the protection of critical infrastructures. For the purposes of this report, we define critical infrastructure as infrastructure whose failure would result in substantial damage to society and/or the economy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.315-327
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• 2013

Wireless Body Area Network (WBAN) is a network around a human body within 3~5m which consists of medical or non-medical device. WBAN has to satisfy many kinds of demands such as low-power, a variety of data rate and a data priority. Especially, it is hard for the nodes for monitoring vital signs to replace battery. Thus energy and channel efficiency is important because the battery power is limited. In this thesis, a novel algorithm for reducing the energy consumption is proposed. The proposed algorithm adjusts transmission period according to traffic. by means of determining transmission period by amount of data, the node can reduce energy consumption. Energy detection is performed in order to guarantee data priority before attempting to transmit. In case of failing to transmit, it is proposed that energy consumption is reduced through avoiding collision by changing priority. The comparison result shows that the proposed algorithm reduces power consumption and increasing maximum channel efficiency by avoiding collision.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.791-796
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• 2012

A RF limiter is a component to protect the receiver front end from undesired signal. A RF limiter is a key component whose output is constant level for all inputs above a critical value. A RF limiter use a diode to pass signals of low power while attenuating those above some threshold. A RF limiter for receiver protection in modern radar systems is playing a vital role in order to meet challenges of new interference threats and complicated electromagnetic environments. This paper proposed a new circuit for high power RF limiter whose structure is the combination of the PIN diode and Limit diode. PIN diode take a use of its isolation characteristics which act as a switch does. A 2 kW RF limiter with 200 us pulse width at S-band was developed. It shows good agreements between estimated value and measured results.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.123-130
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• 2016

High-frequency induction heating equipment can heat the metal by applying a High-Frequency power to the resonant circuit. The resonance circuit is composed of the work coil and the conduction-cooled power capacitor, it influences the performance of the heat treatment equipment according to the characteristics of the capacitor. However, dependence on conduction-cooled power capacitor's import is high due to lack of core technology research and development. Minimizing the generation of internal heat transmitted inside during LC resonance, reduce the reactive power loss, there is a need for a capacitor within the voltage characteristic outstanding. To implement localization it is vital that prior study of the analysis on the frequency response characteristic for the finished capacitor advanced manufacturer be implemented. Studying the interpolation method to read the value at any point of the characteristic curve for a given log-log scale was applied to the analysis tool of the capacitor by my proposed algorithm. The simulation for reproducing frequency response curves was attempted by assuming a capacitor in a simplified series equivalent RC circuit to obtain the equivalent series resistance value. It was confirmed that the reproduction rate was the result value above 83% as compared to the simulation of the properties and characteristics on the actual reactive power for Peak value, and that the algorithm can be applicable when analyzing and predicting the characteristic curves of a simpled model capacitor.

• The Korean Journal of Rehabilitation Nursing
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• v.3 no.2
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• pp.196-211
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• 2000

The purpose of this study was to determine the effects of 5 weeks self-help management program on reducing depression, promoting Activity of Daily Livings(ADLs), Instrumental Activity of Daily Livings(IADLs), grasping power, hope and self-efficacy for post stroke patients visiting public health care centers in Seoul. This was pre-experimental study, and the subjects were 27 post stroke hemiplegic patients. The program was composed of five sessions and each session had health education on stroke, ROM exercise and recreation. Data were collected from May to November, 2000, and all subjects were asked to complete the Questionnaires, be measured vital signs and grasping power. Data were analyzed with frequency, percent, paired t-test, and Pearson's correlation coefficient using SAS(version 6.12) program. The results were as follows : 1) The scores of ADLs were increased from 27.04 to 28.22 after program, and that was statistically significant(p=.005). 2) The scores of IADLs were increased from 18.70 to 19.78 after program, and that was statistically significant(p=.004). 3) The grasping power of right hand were increased from 21.87kg to 26.93kg after program, and that was statistically significant(p=.002). But the grasping power of left hand were statistically insignificant(p=.919). 4) The scores of depression were decreased from 39.63 to 35.30 after program, and that was statistically significant(p=.030). 5) The scores of hope were increased from 30.89 to 34.15 after program, and that was statistically significant(p=.002). 6) The scores of self-efficacy were increased from 67.70 to 76.37 after program, and that was statistically significant(p=.000). According to the results of this study, the scores of Activity of Daily Livings(ADLs), Instrumental Activity of Daily Livings (IADLs), hope, and self-efficacy and the grasping power were improved and depression was reduced in post stroke patients participating in self-help management program. Therefore we recommend to use self-help management programs as a nursing intervention for the post stroke patient.

• Clean Technology
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• v.20 no.4
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• pp.449-456
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• 2014

There has been increasing concerns for the problems of water security in countries, caused by the frequent occurrence of localized drought due to the climate change and uncertainty of water balance. The importance of fresh water is emphasized as considerable amount of usable fresh water is utilized for power generation sector producing electricity. PV power system, the source of renewable energy, consumes water for the every steps of life cycle: manufacturing, installation, and operation. However, it uses relatively less water than the traditional energy sources such as thermal power and nuclear power sources. In this study, to find out the use of water for the entire process of PV power system from extracting raw materials to operating the system, the footprint of water in the whole process is measured to be analyzed. Measuring the result, the PV water footprint of value chain was $0.989m^3/MWh$ and the water footprint appeared higher specially in poly-Si and solar cell process. The following two reasons explain it: poly-Si process is energy-intensive process and it consumes lots of cooling water. In solar cell process, deionized water is used considerably for washing a high-efficiency crystalline silicon. It is identified that PV system is the source using less water than traditional ones, which has a critical value in saving water. In discussing the future energy policy, it is vital to introduce the concept of water footprint as a supplementary value of renewable energy.

• Korean Security Journal
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• no.4
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• pp.257-277
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• 2001

The purpose of this study was to examine effects of practicing martial arts upon job performance of employees engaged in security industry. For positive investigation, 400 employees were questioned using some questionnaires; as a result, we obtained the following conclusion of the relation between the extent of the practicing martial art and the ability of performing their jobs. First, the more they practice martial art, the better and higher their mental health and psychological stability more than control group. Especially, when crime is reported to them or they arrest a criminal taken in an act of crime, the degree of their anxiety was low and they strongly expose self-confidence, their view of moral achievement and their sense of morality. Second, the more they practice martial art, the higher their ability of arrestment a criminal in an act and self-defense is. Because practicing martial art make their vital power and physical strength promoted. Third, the more they practice martial art, the more sincere the trust and friendship among colleagues are. As well they seem to feel strong solidarity oneanother. But practicing martial art appeared that it doesnt have an effect on coping with complications among generations and the gaps between master sergeant and them. Fourth, employees engaged in security industry practicing martial art is not only used in job performance merely as a technique; it is also effective on the mind that it make their anxiety dissolved and give them self-confidence.

• Journal of Astronomy and Space Sciences
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• v.30 no.3
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• pp.187-192
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• 2013

Honsangui (celestial globe) which is a water-hammering method astronomical clock is recorded in "Juhaesuyong" which is Volume VI of supplement from "Damheonseo", written by Hong Dae-Yong (1731~1783). We made out the conceptual design of Hong Dae-Yong's Honsangui through the study on its structure and working mechanism. Honsangui consist of three rings and two layers, the structure of rings which correspond to outer layer is similar to his own Tongcheonui (armillary sphere) which is a kind of armillary sphere. Honsang sphere which correspond to inner layer depicts constellations and milky way and two beads hang on it as Sun and Moon respectively for realize the celestial motion. Tongcheonui is operated by the pendulum power but Honsangui is operated by water-hammering method mechanism. This Honsangui's working mechanism is the traditional way of Joseon and it was simplified the working mechanism of Shui y$\ddot{u}$n i hsiang t'ai which is a representative astronomical clock of China. This record of Honsangui is the only historical record about the water-hammering method working mechanism of Joseon Era and it provide the study of water-hammering method mechanism with a vital clue.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.10
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• pp.2473-2492
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• 2012

Energy conservation is a vital issue in wireless sensor networks. Recently, employing mobile sinks for data gathering become a pervasive trend to deal with this problem. The sink can follow stochastic or pre-defined paths; however the controlled mobility pattern nowadays is taken more into consideration. In this method, the sink moves across the network autonomously and changes its position based on the energy factors. Although the sink mobility would reduce nodes' energy consumption and enhance the network lifetime, the overhead caused by topological changes could waste unnecessary power through the sensor field. In this paper, we proposed EEDARS, an energy-efficient dual-sink algorithm with role switching mechanism which utilizes both static and mobile sinks. The static sink is engaged to avoid any periodic flooding for sink localization, while the mobile sink adaptively moves towards the event region for data collection. Furthermore, a role switching mechanism is applied to the protocol in order to send the nearest sink to the recent event area, hence shorten the path. This algorithm could be employed in event-driven and multi-hop scenarios. Analytical model and extensive simulation results for EEDARS demonstrate a significant improvement on the network metrics especially the lifetime, the load and the end-to-end delay.