• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.259-270
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• 2005

This paper proposes a mathematical model to analyze call-and packet-level performance of the TD-CDMA/TDD system which could serve a flexible radio resource management against multi-type heterogeneous and asymmetrical traffic conditions. On call-level analysis, the mathematical model based on queueing theory performs multi-dimensional operations using random vectors or matrices to consider multiple types of traffic and also deal with asymmetrical up- and down-direction transmissions separately. Employing the mathematical model, we obtain rail blocking probability for each type of traffic and also the optimum switching-point with the smallest call flocking probability. And on packet-level analysis, employing a non-prioritized queueing scheme between circuit and packet calls, we solve 2-dimensional random vector problem composed of the queue length for packets and the number of circuit calls being served. Finally, packet-level performance is analyzed in terms of the packet loss probability and the buffer size required under mixed-traffic conditions of multiple types of circuit and packet calls.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.05a
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• pp.473-483
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• 2003

본 논문은 안전해석 등에 사용되는 RETRAN-3D 등 최적해석 코드를 기반으로 하면서도 복잡한 하드웨어 없이 간편한 GUI (Graphic User Interface)를 이용하여 광범위한 발전소 과도상태를 해석하기 위한 다양한 기능을 통해 시뮬레이션 조작을 쉽게 할 수 있는 웨스팅하우스형 950MW급 최적 원전운전분석기 (Nuclear Plant Analyzer)를 다루고자 한다. WH형 950MW 원전 운전최적분석기는 기존의 단순한 Point Kinetics 모델이 아닌 정교한 3D 실시간 노심모델과 RETRAN 코드를 기반으로 하는 실시간 NSSS 열수력 모델 (ARTS)이 통합된 모델을 갖추고 있으며, 해당형식발전소 (WH 3 Loop PWR Plant : 고리 3,4호기, 영광1,2호기 원전)의 여러 가지 과도사고를 실시간으로 정상, 비정상, 비상운전 등으로 모의할 수 있도록 개발되었다. 모의결과 주요 과도 상태의 결과가 해석한 결과와 잘 일치하였으며, 해당형식 발전소 과도 분석이나 규제요원 훈련에 이용될 계획이다.

• The Transactions of the Korea Information Processing Society
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• v.13 no.7
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• pp.291-298
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• 2024

Despite its wide application, cloud computing raises privacy leakage concerns because users should send their private data to the cloud. Homomorphic encryption (HE) can resolve the concerns by allowing cloud servers to compute on encrypted data without decryption. However, due to the huge computation overhead of HE, simply executing an entire cloud program with HE causes significant computation. Manually partitioning the program and applying HE only to the partitioned program for the cloud can reduce the computation overhead. However, the manual code partitioning and HE-transformation are time-consuming and error-prone. This work proposes a new homomorphic encryption enabled annotation-guided code partitioning compiler, called Heapa, for privacy preserving cloud computing. Heapa allows programmers to annotate a program about the code region for cloud computing. Then, Heapa analyzes the annotated program, makes a partition plan with a variable list that requires communication and encryption, and generates a homomorphic encryptionenabled partitioned programs. Moreover, Heapa provides not only two region-level partitioning annotations, but also two instruction-level annotations, thus enabling a fine-grained partitioning and achieving better performance. For six machine learning and deep learning applications, Heapa achieves a 3.61 times geomean performance speedup compared to the non-partitioned cloud computing scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.939-950
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• 1992

The performance of common spreading code scheme employing multiple-capture receiver is compared to that of transmitter-oriented (T/O) code division multiple access (CDMA) scheme in view of the possibility of collision-free transmissions and the effect of secondary multiple-access interference. For performance comparisons, secondary multiple-access interference is characterized for the common code scheme and the T/O CDMA scheme that assures perfectly collision-free transmissions. Throughput performance is then evaluated for these two schemes with direct-sequence spread-spectrum/differential-phase-shift-keying (DS-SS/DPSK) data modulation and forward-error-control coding (BCH codes) in the presence of an additive white Gaussian noise (AWGN). It is shown that when the number of radios is relatively large, the maximum normalized throughput is greater for the common code scheme than for the T/O CDMA scheme at a moderate signal-to-noise ration(SNR).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.214-216
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• 2010

본 논문에서는, 다중송수신안테나 직교주파수분할다중화 (MIMO-OFDM) 시스템에서 심볼 기반 빔포밍을 위한 제한 피드백 기법을 고려하였다. 공간적 상관도가 존재하는 다중전달경로 채널에서, 심볼 기반 빔포밍을 위한 제한 피드백 기법과 코드북을 제안하였다. 모의실험 결과를 통해 제안한 기법이 낮은 복잡도를 가짐에도 불구하고 기존의 iterative 알고리즘을 기반으로 하는 심볼 기반 빔포밍을 이용한 제한 피드백 기법보다 우수한 성능을 보임을 확인하였다. 또한, 제안한 코드북이 랜덤 벡터 양자화 코드북보다 우수한 성능을 보임을 확인하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.269-274
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• 1996

월성원자력발전소 2호기와 같은 CANDU 6형 원자로의 반응도제어기구 설치대에는 여러 반응도제어기구가 삽입되기때문에 원자로심으로부터의 방사선흐름현상으로 인한 방사선피폭이 예상될 수 있는 위치이다. 좁고 긴 반응도제어기구 도관에서의 방사선 흐름으로 인한 반응도제어기구 설치대에서의 방사선량을 예측하기 위해 몬테 칼로 MCNP 코드를 1차원 각분할법 코드인 ANISN과 연계하여 사용하였다. 월성원자력2호기의 상단차폐해석을 위한 ANISN 계산, 도관의 방사선흐름을 평가하기 위한 MCNP 계산, 그리고 반응도제어기구 설치대에서의 방사선량율 평가를 위한 MCNP 계산등 3단계 계산 기법의 적응이 시도되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.31-41
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• 2000

It has been known that the optical code division multiple access (OCDMA) is a prominent future technology to support many simultaneous users and to increase transmission capacity of optical fiber. In this paper, we proposed the new construction of 2 dimensional code, which can be used as a codeword in temporal/wavelength OCDMA networks. New code family is obtained by extending the concept of Hamming correlation. All optical encoder and decoder for newly proposed code were also developed. In considering bit error ratio, we verified that new coding scheme outperforms conventional coding scheme by simulation. This system is applicable to asynchronous fast local area network, which needs a high security level and a flexible network configuration.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.69-76
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• 2018

This paper studies the Turbo Codes, the concatenation of Turbo Codes and Reed-Solomon (RS) codes on Orthogonal frequency-division multiplexing (OFDM) in digital communication channel, and then analysis the performances of the new concatenated Forward Error Correct (FEC) scheme applied to an OFDM system based on the digital terrestrial video broadcasting (DVB-T) scheme. We compared the results with the standard DVB-T convolutional codes performances on Additive White Gaussian Noise (AWGN) channels. The simulation results shown that by employing turbo codes with only a few numbers of iterations, the performances of the overall system can be improved significantly. These results will be obtained by applying an appropriate interleaver technique in the concatenated FEC procedure.

• Journal of Software Engineering Society
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• v.24 no.1
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• pp.27-33
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• 2011

The importance of the low-power management has increased due to the recent advances of the embedded systems. However, it is noted that low-power concerns are detrimental to the readability and the maintainability of the codes for the core concerns. In this study, in order to reduce occurring leakage power during run-time, we present a power management while considering the run-time leakage power of devices. the power management codes is separated from the core concern codes by applying aspect-oriented programming. Finally, we analyze the theoretical model of our proposed scheme and present experimental results.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.415-417
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• 2002

날로 커져가는 3D 모델을 효율적으로 사용하기 위한 노력으로 압축처리 방법들이 연구되고 있다. 본 논문에서는 3D 모델의 메쉬를 Layer로 분할하여 Vertex Layer와 Triangle Layer를 생성 후, 삼각형들을 몇가지 연산코드로 분류하여 압축(compression)하는 방법을 제안한다. Triangle Layer는 기본 정점으로부터 연결된 선분의 정점들로 이루어진 Vertex Layer의 쌍을 이용하여 만들어진다. 이 Triangle Layer에 해당 되는 삼각형들의 연결 정보를 제안한 연산코드로 분류하고, 이것을 엔트로피 코딩하여 3D 모델을 압축한다. 이 기법은 삼각형의 형태를 기준으로 한 개나 두 개의 삼각형을 하나의 연산코드로 분류하거나 삼각형의 연결 상황에 따라 하나의 연산코드로 분류하여 연결정보를 표현한다. 복원(decompression)시에는 연산 코드를 이용하여 삼각형의 연결정보를 뽑아내면 원 상태의 3D 모델을 획득할 수 있다. 이 방법은 연결 정보를 무손실 압축하는 방법으로, 지금까지 제안된 압축기법과 비교할 때, 간단하면서도 월등한 압축 효과를 볼 수 있다.