• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.254-259
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• 2014

In this paper, we describe construction of a wind stabilization demo-site and effects of output power control of wind turbines for suppression of ramp rate using ESS (Energy Storage System). It is difficult to control the output power of distributed generator such as wind turbine which of variation is very large. If the large capacity wind farm be interconnected into power system may cause blackout due to Power Quality. For these reasons, the international standards such as Grid-Code is limited to less than 10 [%/min] of renewable energy ramp rate. The case of Korea, government actively conducts propagating large-scale renewable energy for green growth policy, to interconnecting more renewable energy into power system is necessary for stabilization technology. For these reasons, the POSCO consortium has constructed a wind stabilization demo-site that is configured as 500 [kWh] battery energy storage systems can output up to 3 [C-Rate] and two wind turbines rated 750 [kW]. In POSCO consortium, which implements various methods stabilizing output power of wind turbine such as smoothing, section firming and ramp control, we derive the results of long-term demonstration that can be controlled to satisfy to the international standard about ramp rate [%/kW] of wind turbine output power.

• Journal of Digital Convergence
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• v.13 no.1
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• pp.313-319
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• 2015

As the number of applications using the internet the rapidly increasing incidence of cyber attacks made on the internet has been increasing. In the equipment of L3 DDoS attack detection equipment in the world and incomplete detection of application layer based intelligent. Next-generation networks domestic product in high-performance wired and wireless network threat response techniques to meet the diverse requirements of the security solution is to close one performance is insufficient compared to the situation in terms of functionality foreign products, malicious code detection and signature generation research primarily related to has progressed malware detection and analysis of the research center operating in Window OS. In this paper, we describe the current status survey and analysis of the latest variety of new attack techniques and analytical skills with the latest cyber-attack analysis prejudice the security situation.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.92-97
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• 2009

It is more necessary to consider the various factors for developmenting visible PV module of alternative window than traditional PV module. It must have sufficient performance which is Tvis, daylighting, daylight factor, glare index. so that more needs to consider suitable plan and total evaluated technology. Under the this background. For using commonly a combination BIPV module system and Daylinghting that can alternative architectural window, our goal on this study is drawing proper window area ratio as the window by analyzing lighting performance and glare index depending on transmittance of DSSC. On this study, we drew the result about window area ratio that can apply in the building when applying DSSC in the window. In situation that window is alternated as curtain wall in atrium that has big Widow area, if applying red 15.8% DSSC of low transmittance, it is expect to proper because it is suitable illumination standard and doesn't occur a discomfort glare. In case of office, we propose to apply red 33.2% or blue 35.2% DSSC of high transmittance for no affecting lighting load. we expect to contribute to select proper and effective window when applying the window in the building by drawing the window area ratio that can apply in thee building depending on transmittance of DSSC and offering the glare index data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.1012-1020
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• 2011

In this paper a design of $\pi$/4-DQPSK baseband receiver for the exchange of digital data and e-mail between shore and ship stations and/or among ship stations in the maritime mobile service VHF channels is described. Due to the permitted relatively big frequency instability of local oscillators at the transmitter and the receiver of maritime communication system, the designed baseband receiver should have the capabilities of correct estimation and compensation of the synchronization parameters, such as symbol timing and frequency offset, from the received signal which might include relatively big frequency error. Simulated BER results show that the designed baseband receiver works less than 0.5dB loss under AWGN channel when the normalized frequency offset of the received signal is more then 20%.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.41-51
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• 2018

Format preserving encryption(FPE) performs encryption with preserving the size and format of plain-text. Therefore, it is possible to minimize the structural change of the database before and after the encryption. For example, when encrypting data such as credit card number or social security number, it is possible to maintain the existing database structure because FPE outputs the same form of cipher-text as plain-text. Currently, the National Institute of Standards and Technology (NIST) recommends FF1 and FF3 as standards for FPE. Recently, in Korea, FEA, which is a very efficient FPE algorithm, has been adopted as the standard of FPE. In this paper, we analyze FEA and measure the performance of FEA by optimizing it in various environments.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1419-1429
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• 2017

Recently, environment based authentication technique had proposed reinforced authentication, which generating statistical model per user after user login history classifies into account takeover or legitimate login. But reinforced authentication is likely to be attacked if user was not attacked in past. To improve this problem in this paper, we propose unconsciousness authentication technique that generates 2-Class user model, which trains user's environmental information and others' one using machine learning algorithms. To evaluate performance of proposed technique, we performed evasion attacks: non-knowledge attacker that does not know any information about user, and sophisticated attacker that only knows one information about user. Experimental results against non-knowledge attacker show that precision and recall of Class 0 were measured as 1.0 and 0.998 respectively, and experimental results against sophisticated attacker show that precision and recall of Class 0 were measured as 0.948 and 0.998 respectively.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.81-89
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• 2013

This paper considers the steering characteristics of a four-row tracked vehicle crawling on extremely cohesive soft soil, where each side is composed of two parallel tracks. The four-row tracked vehicle (FRTV) is assumed to be a rigid body with 6-DOF. A dynamic analysis program for the tracked vehicle is developed using the Newmark-${\beta}$ method based on an incremental-iterative scheme. A terra-mechanics model of an extremely cohesive soft soil is implemented in the form of the relationships of the normal pressure to the sinkage, the shear resistance to the shear displacement, and the dynamic sinkage to the shear displacement. In order to investigate the steering characteristics of the four-row tracked vehicle, a series of dynamic simulations is conducted with respect to the distance between the left and right tracks (pitch), steering ratios, driving velocity, reference track velocity, lengths of the tracks, and properties of the cohesive soft soil. Through these numerical simulations, the possibility of using a kinematic steering ratio is explored.

• Journal of Korean Institute of Architectural Sustainable Environment and Building Systems
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• v.12 no.6
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• pp.591-605
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• 2018

The information on the planar figure of the building envelope is commonly required in various criteria related to the energy performance of the building. However, since the method of creating varies depending on each criterion, the information displayed in the planar figure of the building envelope differs considerably according to the person making the figure. In this regard, this study sought to derive the commonly required information for the unification of the information included in the planar figure of the building envelope, and thus examine the standardization of the planar figure of the building envelope based on BIM. Towards this end, 1) the required information about the planar figure of the building envelope was derived through the literature review and case analysis results submitted to the energy performance evaluation agencies, and 2) the standardized output technology using IFC was investigated based on the required information. Therefore, it is expected that the findings of this study will help to create a general-purpose planar figure for the building envelope, and this study can serve as the preliminary research for automatically extracting the information on the planar figure of the building envelope.

• Journal of the Korean GEO-environmental Society
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• v.20 no.3
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• pp.15-20
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• 2019

A large amount of site investigation data is essential to obtain reliable design value. However, site investigations are generally insufficient due to economic problems. It is important to estimate the ground profile information in unboring region for accurate earthwork-volume prediction, and such ground profile information can be estimated by using the geo-statistical approach. Furthermore, the ground profile information in unboring region can be estimated by training a model via machine learning technique such as artificial neural network. In this paper, artificial neural network-based model estimated the ground profile information in unboring region, and this results were compared with that of ordinary kriging technique, which is referred to the geo-statistical approach. Accordingly, a total of 84 ground profile information in an actual bridge environment was split into 75 training and 9 test databases. The observed ground profile information of the test database was compared with those of the ordinary kriging technique and artificial neural network.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.61-68
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• 2020

7-tonf turbopump real-propellant tests in Naro Space Center were conducted and high-frequency signals from an accelerometer and pressure sensors installed on the casing and the inlet/outlet pipeline of LOX pump were analyzed to estimate the structural and hydrodynamic stabilities. Waterfalls, frequency spectrums and RMS(Root Mean Square) values of the measured signals were calculated and characteristic instability frequencies by the rotating cavitation and the rear floating ring seal(F.R.S) were investigated. Static pressures of the inlet/outlet pipeline and an acceleration of the pump casing are strongly affected on pressure fluctuation induced by the rear floating ring seal in the leakage path. Despite the acceleration RMS value seems totally small, the rotating-speed-related synchronous frequency affecting the shaft instability is distinctly observed in the frequency contour.