• 한국컴퓨터정보학회논문지
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• 제17권1호
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• pp.203-209
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• 2012

최근 무선방송 환경을 기반으로 하는 k-최근접(k-Nearest Neighbor) 질의처리가 활발히 연구되고 있다. 무선방송환경의 장점은 서버 내에 존재하는 불특정 다수에게 일괄적으로 질의처리를 할 수 있는 확장성을 가진다는 것이다. 그러나 기존의 k-NN 질의는 무선방송환경에 적용할 경우 탐색과정에서 백트래킹이 발생하여 질의처리시간이 증가하는 단점을 가진다. 본 논문은 무선방송환경에서 k-NN 질의를 효과적으로 처리하기 위하여 계층적 비트맵 기반 공간색인(Hierarchical Bitmap-based Spatial Index: HBI)을 제안한다. HBI는 비트맵 정보와 트리 구조를 이용하여 비트맵의 크기를 줄인다. 결과적으로 방송주기를 줄임으로써 클라이언트의 청취시간과 질의처리 시간을 줄일 수 있다. 또한 비트맵 정보를 활용하여 객체의 위치를 모두 파악할 수 있기 때문에 필요한 데이터를 선택적으로 청취할 수 있다. 본 논문에서는 HBI를 k-NN 질의에 적용하여 실험을 실시하고 성능평가에서 제안 기법이 우수함을 증명한다.

• 한국정보처리학회논문지
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• 제7권3호
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• pp.1013-1020
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• 2000

In this paper, we propose an algorithm which segments hierarchically blocks of image using discrete cosine transform(DCT) and execute finite-state vector quantization (FSVQ) for each block. Using DCT coefficient feature, image is segmented hierarchically to large smooth block and small edge block, then the block hierarchy informations are transmitted. The codebooks are respectively constructed for each hierarchical blocks, the encoder transmits codeword index using FSVQ for reducing encoded bit with hierarchical segmentation. Compared with side match VQ(SMVQ) and hierarchical FSVQ(HFSVQ) algorithm, about Zelda and Boat image, the new algorithm shows better picture quality with 1.97dB and 2.85 dB difference as to SMVQ, 1.78dB and 1.85dB diffences as to HFSVQ respectively.

• 대한교통학회지
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• 제27권3호
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• pp.49-58
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• 2009

대전시를 사례로 위계수준을 달리한 4개의 노선망 대안(대안 1은 위계가 없는 노선망, 대안 2, 대안 3, 대안 4는 각각 초급, 중급, 상급 수준의 위계를 가진 노선망)을 작성하고, 평가지표(차내통행시간비용, 대기시간비용, 환승페널티비용)를 산출하여 대안간 비교를 통해 효율성을 분석하였다. 차내통행시간비용은 위계가 높은 대안일수록 감소하다가 위계가 매우 높아지면 다시 증가하는 것으로나타났다. 대기시간 비용은 위계가 높은 대안일수록 큰폭으로 감소하며, 환승페널티비용은 위계가 높은 대안일수록 증가하는 것으로 나타났다. 종합적으로 볼 때 총통행비용은 위계가 있는 노선망이 위계가 없는 노선망에 비하여 낮은 것으로 나타나 위계구조를 가진 노선망의 효율성이 높은 것으로 나타났다. 위계가 있는 노선망 중에서는 위계가 높을수록 총통행비용이 감소하다가 위계가 지나치게 높아지게 되면 오히려 증가하는 특성을 보임으로써 중급수준의 위계를 가진 노선망이 가장 효율성이 높은 것으로 분석되었다.

• Journal of Theoretical and Applied Mechanics
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• 제3권1호
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• pp.16-33
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• 2002

A concept of hierarchical modeling, the newest modeling technology. has been introduced early In 1990. This nu technology has a goat potential to advance the capabilities of current computational mechanics. A first step to Implement this concept is to construct hierarchical models, a family of mathematical models which are sequentially connected by a key parameter of the problem under consideration and have different levels in modeling accuracy, and to investigate characteristics In their numerical simulation aspects. Among representative model problems to explore this concept are elastic structures such as beam-, arch-. plate- and shell-like structures because the mechanical behavior through the thickness can be approximated with sequential accuracy by varying the order of thickness polynomials in the displacement or stress fields. But, in the numerical analysis of hierarchical models, two kinds of errors prevail: the modeling error and the numerical approximation errors. To ensure numerical simulation quality, an accurate estimation of these two errors Is definitely essential. Here, a local a posteriori error estimator for elastic structures with thin domain such as plate- and shell-like structures Is derived using element residuals and flux balancing technique. This method guarantees upper bounds for the global error, and also provides accurate local error Indicators for two types of errors, in the energy norm. Comparing to the classical error estimators using flux averaging technique, this shows considerably reliable and accurate effectivity indices. To illustrate the theoretical results and to verify the validity of the proposed error estimator, representative numerical examples are provided.

• Structural Engineering and Mechanics
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• 제8권5호
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• pp.513-529
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• 1999

A concept of hierarchical modeling, the newest modeling technology, has been introduced in early 1990's. This new technology has a great potential to advance the capabilities of current computational mechanics. A first step to implement this concept is to construct hierarchical models, a family of mathematical models sequentially connected by a key parameter of the problem under consideration and have different levels in modeling accuracy, and to investigate characteristics in their numerical simulation aspects. Among representative model problems to explore this concept are elastic structures such as beam-, arch-, plate- and shell-like structures because the mechanical behavior through the thickness can be approximated with sequential accuracy by varying the order of thickness polynomials in the displacement or stress fields. But, in the numerical, analysis of hierarchical models, two kinds of errors prevail, the modeling error and the numerical approximation error. To ensure numerical simulation quality, an accurate estimation of these two errors is definitely essential. Here, a local a posteriori error estimator for elastic structures with thin domain such as plate- and shell-like structures is derived using the element residuals and the flux balancing technique. This method guarantees upper bounds for the global error, and also provides accurate local error indicators for two types of errors, in the energy norm. Compared to the classical error estimators using the flux averaging technique, this shows considerably reliable and accurate effectivity indices. To illustrate the theoretical results and to verify the validity of the proposed error estimator, representative numerical examples are provided.

• Journal of Information Processing Systems
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• 제14권3호
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• pp.694-708
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• 2018

China possesses a passenger dedicated line system of large scale, passenger flow intensity with uneven distribution, and passenger nodes with complicated relations. Consequently, the significance of passenger nodes shall be considered and the dissimilarity of passenger nodes shall be analyzed in compiling passenger train operation and conducting transportation allocation. For this purpose, the passenger nodes need to be hierarchically divided. Targeting at problems such as hierarchical dividing process vulnerable to subjective factors and local optimum in the current research, we propose a clustering approach based on self-organizing map (SOM) and k-means, and then, harnessing the new approach, hierarchical dividing of passenger dedicated line passenger nodes is effectuated. Specifically, objective passenger nodes parameters are selected and SOM is used to give a preliminary passenger nodes clustering firstly; secondly, Davies-Bouldin index is used to determine the number of clusters of the passenger nodes; and thirdly, k-means is used to conduct accurate clustering, thus getting the hierarchical dividing of passenger nodes. Through example analysis, the feasibility and rationality of the algorithm was proved.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2001년도 추계학술대회 논문집
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• pp.111-115
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• 2001

A good business performance measurement system is an effective tool io sustained growth in profits. Although interest in creating performance measurement models is widespread, a well-designed system is rare. To be successful in today's competitive environment, a performance measurement system should incorporate strategic success factors and contain financial and non-financial measuring index to carry out strategic management. In the 1990s, Kaplan & Norton introduced a concept called the Balanced Scorecard. The Balanced Scorecard supplements traditional financial measures with criteria that measured performance from three additional perspectives - those perspectives of customers, internal business processes, and learning and growth. This paper presents five measuring index criteria for each perspective. To calculate the relative priority for These measuring index, we investigate weights investigated by interviews with management consultant. Then, AHP method is employed for calculating priority weight. Our evaluation model may be referred to as the Balanced Analytic Hierarchical Performance Model(BAHPM) in the sense that the analytic hierarchical scheme, along with the AHP, is applied. The BAHPM is the first kind of analytical model to cover a wide variety of measures. In comparison with previous evaluation models, our model shows strengths in structural flexibility, ease of incorporating feedback, group evaluation capacity, participation promotion, sensitivity analysis, and computational simplicity. A prototype based on the BAHPM can be applied to various industry sectors.

• 한국운동역학회지
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• 제30권2호
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• pp.131-144
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• 2020

Objective: The purpose of this study was to examine the effect of degrees of freedom on the multi-synergies in two hierarchies of human hand system during force production and releasing tasks. Method: In this study, the constrained movements of the aiming and releasing actions using both hands and fingers during archery-like shooting were implemented as experimental tasks. The participants produced a pulling force holding the customized frame (mimicking an archery bow, with a set of force transducers) and kept it consistently for about 5 seconds, and released fingers as quickly as possible in a self-paced manner within the next 5 seconds. An analytical method based on the uncontrolled manifold hypothesis was used to quantify the stability index (synergy index) in two hierarchies including two hands (upper hierarchy) and individual fingers (lower hierarchy). Results: The results confirmed that the positive synergy pattern showed simultaneously at the upper and lower hierarchies, and the kinetic degrees of freedom were associated with the increment of hierarchical synergy indices and the performance indices. Also, the synergy indices of both hierarchies showed significant positive correlations with the performance accuracy during the task. Conclusion: The results of this study suggest that the human control system actively uses extra degrees of freedom to stabilize task performance variables. Further increasing the degree of freedom at one level of hierarchy induces positive interactions across hierarchical control levels, which in turn positively affects the accuracy and precision of task performance.

• International Journal of Automotive Technology
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• 제8권3호
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• pp.351-359
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• 2007

In this study, a hierarchical switching control scheme based on robust control theory is proposed for tracking control of vehicle longitudinal acceleration in the presence of large uncertainties. A model set consisting of four multiplicative-uncertainty models is set up, and its corresponding controller set is designed by the LMI approach, which can ensures the robust performance of the closed loop system under arbitray switching. Based on the model set and the controller set, a switching index function by estimating the system gain of the uncertainties between the plant and the nominal model is designed to determine when and which controller should be switched into the closed loop. After theoretical analyses, experiments have also been carried out to validate the proposed control algorithm. The results show that the control system has good performance of robust stability and tracking ability in the presence of large uncertainties. The response time is smaller than 1.5s and the max tracking error is about $0.05\;m/S^2$ with the step input.

• 인터넷정보학회논문지
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• 제12권6호
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• pp.43-51
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• 2011

최근 무선 이동 컴퓨팅 기술과 위치기반 서비스 응용기술 등의 발전으로 과거보다 신속한 질의 처리를 지원할 수 있게 되었다. 그러나 여전히 하드웨어 및 소프트웨어의 기술적 한계가 존재한다. 질의 처리에 있어 가장 중요한 부분은 정확성과 신속성이다. 정확성을 높이기 위해서는 데이터에 상세한 정보를 저장해야 한다. 이 경우 데이터의 정보량이 증가하여 신속성이 떨어지게 된다. 반면에, 신속성을 높이기 위해서는 방송 주기를 줄여야만 얻고자 하는 데이터를 신속하게 얻게 된다. 이 경우 색인 정보의 부족으로 클라이언트의 청취 시간이 증가하여 불필요한 에너지 소모가 발생할 수 있다. 이와 같이, 정확성과 신속성 사이에는 트레이드 오프(trade-off)가 발생한다. 본 논문은 위와 같은 문제점을 극복하기 위해 계층적 비트맵 기반 공간 색인(Hierarchical Bitmap-based Spatial Index: HBI)을 제안한다. 계층적 비트맵 기반 공간 색인은 힐버트 커브(Hilbert Curve) 맵(map) 내에서 객체를 비트(0, 1)로 표기한다. 계층적 비트맵 기반 공간 색인은 비트 정보와 트리 구조를 이용하여 색인크기를 줄이는 방법으로 방송 주기를 줄임으로써 청취 시간과 질의 처리시간을 줄일 수 있다. 또한 계층적 비트맵 기반 공간 색인은 객체의 위치를 모두 파악할 수 있기 때문에 선택적인 청취가 가능하다. 성능평가를 통하여 제안 기법의 우수함을 증명한다.