• 한국통신학회논문지
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• 제31권4B호
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• pp.311-322
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• 2006

P2P(Peer-to-Peer) 시스템은 대용량의 데이터를 공유하는데 유용하며, 네트워크 구조에 따라 중앙 집중형, 구조적 분산형, 그리고 비구조적 분산형으로 분류된다. 이 중 Gnutella와 같은 비구조적 분산형 P2P 시스템은 확장성과 신뢰성 측면에서 장점을 갖지만, 참여하는 노드의 수가 증가함에 따라 데이터를 액세스하는 비용도 증가한다는 문제를 가진다. 데이터 중복을 이용하여 이러한 문제를 해결할 경우 중복된 데이터들의 일관성을 유지하기 위한 기법이 필요하다 본 논문에서는 특정 노드가 데이터를 갱신할 때 중복된 사본을 저장하고 있는 다른 노드에 전파하기 위한 새로운 갱신 전파 알고리즘을 제안한다. 제안한 알고리즘은 타임스탬프와 push/pull 개념을 조합하여 메시지의 전송 오버헤드를 줄일 수 있다는 장점을 갖는다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제13권1호
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• pp.10-20
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• 2024

매년 증가하는 온라인 상거래 시장과, 점차 다양해지는 상품과 콘텐츠로 인해 사용자들은 선택 과정에 어려움을 느낀다. 이에 여러 기업들은 온라인 쇼핑몰에서 사용자가 선호할 상품을 선별하여 제공하기 위해 추천 시스템에 대한 지속적인 연구를 진행하고 있다. 대다수의 추천 시스템 연구에서는 비교적 획득하기 쉬운 사용자의 이벤트 데이터를 기반하여 연구를 진행하였으나 한 종류의 사용자 행동만을 고려하기 때문에 사용자의 선호도를 파악하는 것에 오차가 발생한다. 이에 본 논문에서는 여러 종류의 사용자 행동 데이터의 상관관계를 고려하여 사용자의 선호도를 분석하는 추천 시스템을 제안한다. 제안하는 추천 시스템은 사용자의 사용자 행동 데이터의 상관관계를 분석하고 가중치를 생성하여 추천 모델을 학습한다. 실험에서는 기존 연구의 알고리즘과의 성능 비교를 통해 제안하는 시스템의 복잡도와 성능 향상을 확인하였다.

• Journal of Information Technology Applications and Management
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• 제18권4호
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• pp.119-130
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• 2011

When an organization adopts new technology, performance through the technology is expected to be decided depending on attitudes of the members, in that technology produces performance only if the members zealously use it. Therefore, the members need to devote themselves to acquire and use the new technology. This attitude of members is called "IT acceptance will" (Ranarajan et al., 2005), and this research is to examine the effect of an individual's "IT acceptance will" on performance. Thus, this research analyzes what increases IT acceptance will and what effect IT acceptance will has on stress due to uncertainty of an organization-job complexity and role conflict- through new IT adoption. This research conducted a survey from July to September in 2009, targeting employees of government offices and public institutions in Kyunggi and Kyungnam provinces. Then, a total of 370 was collected and the final 344 was selected for our research analysis. As a result, this research found out that personal innovation and client orientation improved an individual's IT acceptance will, which improved performance through new IT adoption. However, the new IT adoption also increased job complexity and role conflict, but negative effects of stress on performance was not found as IT adoption will diminished the stress. Based on this result, this research discussed practical and academic implications and the limitations.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2006년도 추계 종합학술대회 논문집
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• pp.250-253
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• 2006

본 논문은 컬러 이미지에서 비트플레인의 복잡도를 이용한 적응적 스테가노그라피 방법을 제안하였다. 기존에 비트플레인을 이용한 스테가노그라피 방법들은 대용량의 데이터를 삽입하기 위해 고정 임계값과 가중치를 사용하거나 비트플레인에 따라 가변 크기를 구하여 정보를 삽입하는 반면에 본 논문에서는 컬러이미지에서, 각 커버이미지의 비트플레인의 블록별 복잡도와 삽입할 데이터의 복잡도, 유사도를 측정하고, 비교분석 하여 가장 적합한 비트플레인 블록에 정보를 삽입하는 방법을 제안하였다. 실험 결과 제안 방법은 기존의 방법보다 화질과 삽입 용량 면에서 보다 향상된 결과를 얻을 수 있었다

• 전자공학회논문지B
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• 제33B권4호
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• pp.174-182
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• 1996

In continuous speech recognition system, it is possible to implement the system which can handle unlimited number of words by using limited number of phonetic units such as phonemes. Dividing continuous speech into the string of tems of phonemes prior to recognition process can lower the complexity of the system. But because of the coarticulations between neiboring phonemes, it is very difficult ot extract exactly their boundaries. In this paper, we propose the algorithm ot extract short terms which can represent each phonemes instead of extracting their boundaries. The short terms of lower spectral change and higher spectral chang eare detcted. Then phoneme changes are detected using distance measure with this lower spectral change terms, and hgher spectral change terms are regarded as transition terms or short phoneme terms. Finally lower spectral change terms and the mid-term of higher spectral change terms are regarded s the represent each phonemes. The cepstral coefficients and weighted cepstral distance are used for speech feature and measuring the distance because of less computational complexity, and the speech data used in this experimetn was recoreded at silent and ordinary in-dorr environment. Through the experimental results, the proposed algorithm showed higher performance with less computational complexity comparing with the conventional segmetnation algorithms and it can be applied usefully in phoneme-based continuous speech recognition.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1579-1602
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• 2020

In the design of production system, buffer capacity allocation is a major step. Through polymorphism analysis of production capacity and production capability, this paper investigates a buffer allocation optimization problem aiming at the multi-stage production line including unreliable machines, which is concerned with maximizing the system theoretical production rate and minimizing the system state entropy for a certain amount of buffers simultaneously. Stochastic process analysis is employed to establish Markov models for repairable modular machines. Considering the complex structure, an improved vector UGF (Universal Generating Function) technique and composition operators are introduced to construct the system model. Then the measures to assess the system's multi-state reliability and structural complexity are given. Based on system theoretical production rate and system state entropy, mathematical model for buffer capacity optimization is built and optimized by a specific genetic algorithm. The feasibility and effectiveness of the proposed method is verified by an application of an engine head production line.

• Journal of Computing Science and Engineering
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• 제3권1호
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• pp.1-4
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• 2009

In a given text T of size n, we need to search for the information that we are interested. In order to support fast searching, an index must be constructed by preprocessing the text. Suffix array is a kind of index data structure. The compressed suffix array (CSA) is one of the compressed indices based on the regularity of the suffix array, and can be compressed to the $k^{th}$ order empirical entropy. In this paper we improve the lookup time complexity of the compressed suffix array by using the multi-ary wavelet tree at the cost of more space. In our implementation, the lookup time complexity of the compressed suffix array is O(${\log}_{\sigma}^{\varepsilon/(1-{\varepsilon})}\;n\;{\log}_r\;\sigma$), and the space of the compressed suffix array is ${\varepsilon}^{-1}\;nH_k(T)+O(n\;{\log}\;{\log}\;n/{\log}^{\varepsilon}_{\sigma}\;n)$ bits, where a is the size of alphabet, $H_k$ is the kth order empirical entropy r is the branching factor of the multi-ary wavelet tree such that $2{\leq}r{\leq}\sqrt{n}$ and $r{\leq}O({\log}^{1-{\varepsilon}}_{\sigma}\;n)$ and 0 < $\varepsilon$ < 1/2 is a constant.

• 유통과학연구
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• 제15권7호
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• pp.35-41
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• 2017

Purpose - A product bundling is a marketing approach where multiple products or components are packaged together into one bundle solution. This paper aims to introduce an optimal bundle search problem (hereinafter called "OBSP") which may be embedded with online recommendation system to provide an optimized service considering pairwise discount and delivery cost. Research design, data, and methodology - Online retailers have their own discount policy and it is time consuming for online shoppers to find an optimal bundle. Unlike an online system recommending one item for each search, the OBSP considers multiple items for each search. We propose a mathematical formulation with numerical example for the OBSP and analyzed the complexity of the problem. Results - We provide two results from the complexity analysis. In general case, the OBSP belongs to strongly NP-Hard which means the difficulty of the problem while the special case of OBSP can be solved within polynomial time by transforming the OBSP into the minimum weighted perfect matching problem. Conclusions - In this paper, we propose the OBSP to provide a customized service considering bundling price and delivery cost. The results of research will be embedded with an online recommendation system to help customers for easy and smart online shopping.

• 한국조경학회지
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• 제35권3호
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• pp.50-61
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• 2007

The purpose of this study is to establish design guidelines for waterscape facilities of healing gardens in psychiatric hospitals. Data were collected through simulation and interview. The subjects included schizophrenic (n=42) and alcoholic (n=41) inpatients as well as medical staff personnel (n=40) at Maeumsarang Hospital. The results of this study are as follows: It was revealed that for all three groups the first preference was a natural flowing waterscape, and the second preference was a natural descending waterscape. The schizophrenic subjects had a greater preference for a static artificial waterscape and a descending artificial multistory waterscape than the other two groups. The alcoholic subjects preferred an ascending natural multistory waterscape. The analysis on the preference towards an ascending type and a descending type from the perspective of naturalness and complexity. Complexity had a greater influence than naturalness in the ascending waterscapes, and naturalness had more influence than complexity in the descending style waterscapes. Therefore, these factors need to be taken into consideration when designing either ascending or descending waterscape facilities. In general, the subjects preferred natural, dynamic and descending waterscapes to the artificial, static and ascending variety.

• 한국통신학회논문지
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• 제32권3A호
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• pp.281-289
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• 2007

본 논문에서는 부호 분할 다중 접속 (code division multiple access: CDMA) 시스템에서 의사 잡음 부호 및 반전된 의사 잡음 부호의 획득이 가능하고 데이터 복조도 가능한 위상 변이 네트워크 기반의 차동 순차 추정 기법을 제안하였다. 모의실험을 통해 제안한 기법의 성능이 이제까지의 이중 상관 순차 추정 기법에 비해 낮은 복잡도를 가지면서도 동일한 성능을 지니고 있음을 보였다.