• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.257-261
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• 2008

The Digital Radio Mondiale (DRM) system is a digital broadcasting standard designed for use in the LF, MF and HF bands of the broadcasting bands below 30 MHz. The system provides both superior audio quality and improved user services / operability compared with existing AM transmissions. In this paper, we propose a variable point Prime Factor FFT design method for Digital Radio Mondiale (DRM) system. Proposed method processes a various size IFFT/FFT of Robustness Mode on DRM standard efficiently by composing Radix-Prime Factor FFT Processing Unit of form similar to Radix-4 by insertion of a variable Prime Factor Twiddle Factor and Garbage data. So, we improved limitation that cannot process 112/176/256/288 FFT of each mode of DRM system with a existent Radix Processor and increase memory size and memory access time for IFFT/FFT processing by software processing in case of implementation with a existent high speed DSP.

• Journal of information and communication convergence engineering
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• v.2 no.3
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• pp.182-186
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• 2004

When most of existing instant messengers log on server, they transmit to sever in encoding password to RC5. but RC5 don't be secured because it has been known many of password cracking tools. Also, messengers don't have any protection on the transmitted information with communicating two hosts since loging on, endangering the privacy of the user. As a counter measure, messengers need to provide security service including message encryption. In this paper, we designed a key exchange method of password representing fast, effective and high security degree, using ECC(Elliptic Curve Cryptography) that being known the very stronger than another public key cryptography with same key size. To effectively improve data transmission and its security using IPSec protocol between users, tunnel mode is introduced. Tunnel mode transmits Host-to-Host data through virtual pipelines on the Internet.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.41-49
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• 2012

This paper describes the operation mode development for the grid-tied PMSG(permanent magnet synchronous generator) wind power system combined with a battery energy storage. The development of operation modes was carried out through simulations with PSCAD/EMTDC software and experiments with a 10kW hardware prototype. The detailed simulation models for PMSG wind power system and battery energy storage were developed using user-defined models programed with C-code. A 10kW hardware simulator was built and tested in connection with the local load and the utility power. The simulation and experimental results confirm that the grid-tied PMSG wind power system combined with battery energy storage can supply highly reliable power to the local load in various operation modes.

• Journal of Korea Multimedia Society
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• v.24 no.6
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• pp.815-824
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• 2021

Based on the theory of space perception, this paper concludes that the mixed reality application under the theory of space perception has a three-level definition of visual hierarchy and then analyzes the component elements of interface design and the classification mode of interface windows. Next, carry out case practice research through this theoretical definition, and finally conduct the survey and analysis of questionnaire data, verifying that the mixed reality interface design based on spatial perception theory meets the user experience elements of Usability, Availability, and Attraction. The conclusion is that the constituent elements of interface design and the window classification mode can provide specific and practical design specifications for mixed reality interface design, reduce the interaction cost of completing tasks, reduce users' cognitive load, and make it easier for users to receive interface information

• The Transactions of the Korea Information Processing Society
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• v.1 no.3
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• pp.367-379
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• 1994

This paper describes scheduling algorithms of the UNIX operating system and shows an analytical approach to approximate the average conditional response time for a process in the UNIX operating system. The average conditional response time is the average time between the submittal of a process requiring a certain amount of the CPU time and the completion of the process. The process scheduling algorithms in thr UNIX system are based on the priority service disciplines. That is, the behavior of a process is governed by the UNIX process schuduling algorithms that (ⅰ) the time-shared computer usage is obtained by allotting each request a quantum until it completes its required CPU time, (ⅱ) the nonpreemptive switching in system mode and the preemptive switching in user mode are applied to determine the quantum, (ⅲ) the first-come-first-serve discipline is applied within the same priority level, and (ⅳ) after completing an allotted quantum the process is placed at the end of either the runnable queue corresponding to its priority or the disk queue where it sleeps. These process scheduling algorithms create the round-robin effect in user mode. Using the round-robin effect and the preemptive switching, we approximate a process delay in user mode. Using the nonpreemptive switching, we approximate a process delay in system mode. We also consider a process delay due to the disk input and output operations. The average conditional response time is then obtained by approximating the total process delay. The results show an excellent response time for the processes requiring system time at the expense of the processes requiring user time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.511-520
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• 2011

In this paper, we introduce a multiuser (MU) scheduling method for multiuser amplify-and-forward relay systems, which selects both the transmission mode, i.e., either one- or two-hop transmission, and the desired user via two steps. A closed-form expression for the average achievable rate of the proposed scheduling is derived under two transmission modes with MU scheduling, and its asymptotic solution is also analyzed in the limit of large number of mobile stations. Based on the analysis, we perform our two-step scheduling algorithm: the transmission mode selection followed by the user selection that needs partial feedback for instantaneous signal-to-noise ratios (SNRs) to the base station. We also analyze the average SNR condition such that the MU diversity gain is fully exploited. In addition, it is examined how to further reduce a quantity of feedback under certain conditions. The proposed algorithm shows the comparable achievable rate to that of the optimal one using full feedback information, while its required feedback overhead is reduced below half of the optimal one.

• Asia pacific journal of information systems
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• v.4 no.2
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• pp.35-61
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• 1994

Accounting information system is the most important and formal subsystem of the total information system of an organization which produces and delivers financial information. An organization has its own contigent characteristics. It is the key to a successful development of accounting information system to select the development mode and information characteristics appropriate for the contigent characteristics. The main purpose of this study is to analyze the relationship between the contigent factors and the development mode of accounting information system. In addition, this study will examine the relationship between the contigent variables and the information characteristics of accounting information system. The research method adopted in this study is the survey. The results show that the environmental uncertainty, organization size, task diversity, task interrelatedness, and management commitment are positively related with the involvement and role of user in the system development process. The aggregate information regarding various departments tends to be produced by an organization under the uncertain environment. The information is reported periodically by a centralized organization. The aggregate information is preferred when tha task for implementation is diversified. The output information is more aggregate and provided more frequently when there exists a high interrelatioship between tasks. The output information is more external and reported more frequently in an organization with the high management commitment.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1431-1438
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• 2013

A pack-level battery hardware-in-the-loop simulation (B-HILS) platform is implemented. It consists of dynamic vehicle models using PSAT and multiple control interfaces including real-time 3D driving and GPS mode. In real-time 3D driving mode, user can drive a virtual vehicle using actual drive equipment such as steering wheel and accelerator to generate the cycle profile of the battery. In GPS mode, actual road traffic and terrain effects can be simulated using GPS data while the trajectory is displayed on Google map. In the latter part of the paper, several performance tests of an actual lithium-polymer battery pack are carried out utilizing the developed system. All experiments are conducted as parts of actual development process of a commercial battery pack adopting 2nd generation Prius as a target vehicle model. Through the experiments, the low temperature performance and fuel efficiency of the battery are quantitatively investigated in comparison with the original nickel-metal hydride (NiMH) pack of the Prius.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.5
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• pp.669-674
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• 2012

This study presents the remote control of a mobile robot using iPhone based on Wi-Fi communication. The paper proposes the following set of user interfaces : acceleration mode, arrow touch mode, and jog-shuttle mode. To evaluate the proposed three interfaces, a virtual robot is controlled in a monitor to follow a referenced trajectory using iPhone. In simulation, the standard deviation and summed errors are analysed for showing good and weak points of the proposed three interfaces. The proposed interface replace an additional remote controller requiring cost with a cellular phone. Results of an experiment show that the proposed interfaces can be effectively used for remote robot control.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.107-110
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• 2017

According to researches, while the speed of processor and network in embedded devices is fast enough to meet user requirement, the IO speed is recognized as the main performance bottleneck. Meanwhile it is known that more than 70 percent of IOs are issued from SQLite database. Many researches related SQLite performance optimization is based on WAL mode because WAL mode optimized for write IO performance. In this paper, I propose to optimize SQLite with Atomic Write in the Rollback Journal Mode, which is mainly used in Android and Tizen. I have observed that Atomic Write have a significant write performance improvement(300%) by reducing write, file sync operation and memory usage improvement(80%). Additionally it can block JOJ(Journaling of Journal) and extend the life of the flash memory.