• Proceedings of the Korean Information Science Society Conference
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• 2007.06d
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• pp.243-246
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• 2007

본 논문에서는 802.11b의 네트워크 성능 측정을 통해 도출된 결과를 토대로 하여 802.11b기반의 온라인 게임을 위한 네트워크 엔진을 개발하였다. 네트워크 엔진 서버는 I/O Multiplexing 기법을 사용하였으며, 클라이언트는 .Net Compact Framework로 개발하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.205-209
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• 2000

입출력 장치를 사용하기 위해서는 장치 구동기와 기본적으로 입출력 포트를 제어하는 기능이 요구된다. 본 논문에서는 윈도우즈98 환경에서 이러한 기능을 제공하기 위한 VxD 개발에 관한 기법을 제시하였다. 제시한 기법의 타당성을 검증하기 위하여 입출력 포트 제어용 VxD 프로그램을 개발하고, 실험용 LED 보드를 PIO 포트에 연결하여 VxD의 동작 상태를 확인하였다.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.254-257
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• 1989

In general, unstable phenomena of induction motor are oftenly appeared at low speed and light load. This paper discribes eigenic unstable regions of I.M. itself by computer simulations and the results are compared to experimental ones. And also the optimal design parameters of I.M. which the unstable reg ion can be minimized are determined.

• The Transactions of the Korea Information Processing Society
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• v.4 no.4
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• pp.1076-1088
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• 1997

Data repliciation techniques of distributed database a allocation methods occures to overhead to change together all repkicas for consistency maintenance at updates .In case of data migration horizontal or vertical fragment migration has caused to caused to increase data communication.In this paper we purpose batch proxessing method groups the associated items of table and stores temporary table assciated with file relication and migrations.This method increase the usagility of system buffer in distributed trancsaction processing with a number of data inputs and updates.After all,it improved the perform-ance of distributed transaction system by reducing disk I\O processing time and the cost of data cimmunication among local sites.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1157-1162
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• 2013

We proposed AlGaN/GaN high-electron-mobility transistors (HEMTs) using thermal oxidation for NiOx passivation. Auger electron spectroscopy, secondary ion mass spectroscopy, and pulsed I-V were used to study oxidation features. The oxidation process diffused Ni and O into the AlGaN barrier and formed NiOx on the surface. The breakdown voltage of the proposed device was 1520 V while that of the conventional device was 300 V. The gate leakage current of the proposed device was 3.5 ${\mu}A/mm$ and that of the conventional device was 1116.7 ${\mu}A/mm$. The conventional device exhibited similar current in the gate-and-drain-pulsed I-V and its drain-pulsed counterpart. The gate-and-drain-pulsed current of the proposed device was about 56 % of the drain-pulsed current. This indicated that the oxidation process may form deep states having a low emission current, which then suppresses the leakage current. Our results suggest that the proposed process is suitable for achieving high breakdown voltages in the GaN-based devices.

• Proceedings of the KSRS Conference
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• v.1
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• pp.196-199
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• 2006

Various communication mechanisms have been developed to acquire a meaningful data from sensors. The key requirement during the sensor data acquisition is determinism and reduction of time dependency. It is a fundermental level of satellite data management for controlling satellite operation software data acquisition from sensors or subsystem. Satellite operation software has various software modules to be operated in addition to data acquisition. Therefore, unnecessary time delay shall be minimized to perform the data acquisition. As the result, interrupt method might be prefered than polling method because the former can decrease the restriction of design during implementation of data acquisition logic. The possible problems while using interrupt method like as interrupt latency caused by delaying of interrupt processing time are analyzed. In this paper, communication mechanism which can be used to interface with satellite computer and subsidary subsystem by using interrupt is presented. As well, time dependency between software scheduling and data acquisition is analyzed.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.181-184
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• 2004

본 논문을 통하여 개발된 시스템은 라인카메라를 사용하여 터널의 균열 영상을 획득하기 위하여 사용되는 시스템으로, 터널 내부의 균열 영상을 실시간으로 촬영하여 저장하는 시스템이다. 터널 영상은 의료영상과 같이 작은 손실에도 큰 영향을 미칠 수 있다. 이러한 요소 때문에 본 시스템에서는 CCD 방식의 라인 스캔 카메라를 이용하여 터널 영상을 촬영하며, 이를 저장 하는 방법에 있어서는 비손실 압축기법을 사용하였다. 비손실 압축 기법의 사용을 이용하여 영상을 저장하는 방식은 많은 데이터 저장공간을 필요로 한다. 이러한 문제점은 기술 개발의 놀라운 성장과 더불어 기존 테이프 기반의 방식에서 벗어나 로컬 하드디스크로 직접 저장하는 기법을 사용할 수 있게 되었다. 즉, 라인 카메라를 이용하는 기존 시스템의 경우에는 영상데이타를 실시간으로 저장할 수 없는 문제점 때문에 촬영 속도를 느리게 하면서 영상을 획득하였으며, 획득한 영상을 테이프로 저장하도록 설계되었다. 이에 반하여 본 시스템에서는 테이프를 대신하여 로컬 디스크를 사용하여, 대용량의 영상을 실시간으로 저장할 수 있는 시스템을 개발하였다. 예비실험을 통하여 나타난 결과에 따르면 본 논문을 통하여 개발된 시스템은 약 20Km 이상의 속도로 진행하는 열차에서 터널의 영상을 실시간으로 촬영하여 저장할 수 있음을 살펴볼 수 있었다.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.139-145
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• 2012

Generally, Quicksort selects the pivot from leftmost, rightmost, middle, or random location in the array. This paper suggests Quicksort using middle range pivot $P_0$ and continually divides into 2. This method searches the minimum value $L$ and maximum value $H$ in the length n of list $A$. Then compute the initial pivot key $P_0=(H+L)/2$ and swaps $a[i]{\geq}P_0$,$a[j]<P_0$ until $i$=$j$ or $i$>$j$. After the swap, the length of list $A_0$ separates in two lists $a[1]{\leq}A_1{\leq}a[j]$ and $a[i]{\leq}A_2{\leq}a[n]$ and the pivot values are selected by $P_1=P_0/2$, $P_2=P_0+P_1$. This process repeated until the length of partial list is two. At the length of list is two and $a$[1]>$a$[2], swaps as $a[1]{\leftrightarrow}a[2]$. This method is simpler pivot key process than Quicksort and improved the worst-case computational complexity $O(n^2)$ to $O(n{\log}n)$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.268-275
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• 2003

In this paper, the capacity of VSG-CDMA system supporting multi-media service in the reverse link is analyzed by considering the two models according to the power control and user distribution. In analysis model I, assuming perfect power control and uniform distribution of users, the equation of blocking probability is calculated and the maximum number of voice and data user is derived in accordance with 1 % blocking probability. In analysis model II, it is analyzed by assuming power control error and non-uniform distribution of users. The result of analysis model I means the upper bound of system capacity in the 5 MHz wideband VSG-CDMA system, and the result of analysis model II shows the lower bound of system capacity. Also, the improved plan of performance for VSG-CDMA system is suggested by the analyzed result according to data activity and the value of $E_b/N_o$ in model II.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.5
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• pp.333-337
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• 2007

Flash Translation Layer(FTL) which enables NAND Flash memory-based storage system to be used as a block device is designed considering only characteristics of NAND Flash memory. However, since FTL precesses I/O requests which survived against buffer replacement algorithm, FTL algorithm has tight relationship with buffer replacement algorithm. Therefore, if we do not consider both FTL and buffer replacement algorithms, it is difficult to predict the actual I/O performance of the computer systems that have Flash memory-based storage system. The necessity of FTL and buffer replacement algorithm co-design arises here. In this work, we implemented I/O performance evaluation tool, IPSiNS, which simulates both the buffer replacement and FTL algorithms, simultaneously.