• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.66-76
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• 2016

In this paper, we propose a new hierarchical modulation scheme for DVB-NGH to improve the performance of LP (Low-Parity) signals by applying a conventional constellation-rotation method to the LP signals without virtually a loss of performance of a HP (High-Parity) signals. The improvement of the LP signals is mainly due to the increased divesity gain caused by the constellation-rotation method which barely affect the performance of the HP signals. For the new scheme, we also propose a hardware-efficient ML (Maximum-Likelihood) detection algorithm that first decodes the HP signals by using a conventional HP receiver, and then simply decodes the precoded LP signals based on the pre-detected HP signals.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.331-340
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• 2010

The basic theory and application of new adaptive finite element algorithm have been proposed in this study including the adaptive hp-refinement strategy, and the effective method for constructing hp-approximation. The hp-adaptive finite element concept needs the integrals of Legendre shape function, nonuniform p-distribution, and suitable constraint of continuity in conjunction with irregular node connection. The continuity of hp-adaptive mesh is an important problem at the common boundary of element interface. To solve this problem, the constraint of continuity has been enforced at the common boundary using the connectivity mapping matrix. The effective method for constructing of the proposed algorithm has been developed by using hierarchical nature of the integrals of Legendre shape function. To verify the proposed algorithm, the problem of simple cantilever beam has been solved by the conventional h-refinement and p-refinement as well as the proposed hp-refinement. The result obtained by hp-refinement approach shows more rapid convergence rate than those by h-refinement and p-refinement schemes. It it noted that the proposed algorithm may be implemented efficiently in practice.

• 한국데이터정보과학회:학술대회논문집
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• 2006.04a
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• pp.77-85
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• 2006

본 논문에서는 간이생명표 확장기법인 HP8(Heligman and Pollard 8-parametric) 모형과 spline 내 삽법을 이용한 사망확률 계산 결과를 비교하고 HP8 모형을 우리나라 간이생명표 자료에 적용하여 각 연령별, 연도별호 사망확률을 계산하였다. 그리고 HP8 모형의 8개 모수와 사망확률을 계산하는데 있어 SAS/OR의 NLP procedure를 이용한 결과와 UNO(United Nation)에서 인구통계분석을 목적으로 만든 소프트웨어인 MORTPAK을 이용한 결과를 비교하였다. 분석에 사용한 자료는 통계청에서 제공되는 1971년부터 2003년까지 우리나라 간이생명표 자료이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6A
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• pp.500-505
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• 2009

In this paper, We present a low complexity candidate list generation scheme in iterative MIMO receiver. Since QAM modulation can be decomposed into HP symbols and LP symbol and HP symbol is robust in error capability, we generate HP symbol list with simple ZF detector output and its corresponding neighbor HP symbols, Then, based on HP symbol list, the LP symbol list is generated by using the sphere decoder. From the second iteration, since apriori value from channel decoder is available, the candidate list is updated based on demodulated apriori value. Through the simulation, we observe that at the first iteration, the BER performance is worse than LSD. However, as the number of iteration is increased, the proposed scheme has almost same performance as LSD. Moreover, the proposed one has reduced candidate list generation time and lower number of candidate list compared with LSD.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.7 s.196
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• pp.7-12
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• 2007

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.161-164
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• 2004

모바일 컴퓨팅 환경에서 실시간 데이터베이스 시스템의 트랜잭션 처리시 2PL-HP 방법은 성능이 우수한 스케줄링 기법이다. 그러나 2PL-HP 방법은 높은 우선순위를 갖는 트랜잭션의 선행처리를 항상 보장하기 때문에 낮은 우선순위를 갖는 트랜잭션은 철회 및 블로킹이 불가피하여 기아(starvation) 현상을 초래한다. 본 논문은 이러한 기아 현상으로 인한 낮은 우선순위를 갖는 트랜잭션의 기다림과 철회를 최소화 하기 위해 이타적 잠금 기법에 우선 순위 기법과 2 버전 기법을 이용하였다. 데이터항목을 점유한 트랜잭션이 더 이상 그 데이터항목을 필요로 하지 않을 때 그 데이터항목을 기부함으로 우선순위가 낮은 트랜잭션들의 불필요한 재 시작 및 기다림을 방지한다. 이로써 마감시간 초과비율과 재시작 비율을 감소 시킬 수 있어 시스템의 처리율을 향상 시킬 수 있다.

• Journal of Korea Port Economic Association
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• v.29 no.1
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• pp.67-76
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• 2013

It has been more than four years since the outbreak of global financial crisis. However, the world economy continues to be challenged with new crisis such as the European debt crisis and the fiscal cliff issue of the U.S. The global economic environment remains fragile and prone to further disappointment, although the balance of risks is now less skewed to the downside than it has been in recent years. It's no wonder that maritime business will be bearish since the global business affects the maritime business directly as well as indirectly. This paper, hence, aims to predict the Baltic Dry Index representing the shipping business using the ARIMA-type models and Hodrick-Prescott filtering technique. The monthly data cover the period January 2000 through January 2013. The out-of-sample forecasting performance is measured by three summary statistics: root mean squared percent error, mean absolute percent error and mean percent error. These forecasting performances are also compared with those of the random walk model. This study shows that the ARIMA models including Intervention-ARIMA have lower rmse than random walk model. This means that it's appropriate to forecast BDI using the ARIMA models. This paper predicts that the shipping market will be more bearish in 2013 than the year 2012. These pessimistic ex-ante forecasts are supported by the Hodrick-Prescott filtering technique.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.438-440
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• 2021

With the development of machine learning, artificial intelligence techniques are being applied in various fields. Among these fields, there is an OCR technique that converts characters in images into text. The tesseract developed by HP is one of those techniques. However, the recognition rate for recognizing characters in images is still low. To this end, we try to improve the conversion rate of the text of the image through the post-processing process that recognizes the context using the ontology.

• Korea Multimedia Society
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• v.11 no.1
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• pp.77-85
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• 2007

• Journal of KIISE:Databases
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• v.29 no.6
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• pp.464-476
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• 2002

Main-memory database systems which reside entire databases in main memory are suitable for high-performance real-time transaction processing. If two-phase locking(2PL) as concurrency control protocol is used for the transactions accessing main-memory databases, however, the possibility of lock conflict will be low but lock operations become relatively big overhead in total transaction processing time. In this paper, We designed a real-time static locking(RT-SL) protocol which minimizes lock operation overhead and reflects the priority of transactions and we implemented it on a main-memory real-time database system, Mr.RT. We also evaluate and compare its performance with the existing real-time locking protocols based on 2PL such as 2PL-PI and 2PL-HP. The extensive experiments reveal that our RT-SL outperforms the existing ones in most cases.