• Journal of Digital Convergence
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• v.12 no.1
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• pp.415-421
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• 2014

In this paper, we proposed problem and improvement of halftoning using random space filling curve. Random space filling curve is developed as a solution for shortcoming which space filling curve has self-similarity. It is used to reduce regular pattern can be occurred in constant brightness area in order that randomness apply to scanning path. But there is a problem that some area along scanning path can show too bright result in halftoning using random space filling curve. In this paper, we analyzed cause of problem and proposed single pixel error diffusion as a solution method. This method can avoid over-accumulated error and show better result in halftoning.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.984-990
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• 2009

Halftoning is very important image processing techniques in the digital printing industry which is a process of converting a continuous-tone image to bi-level tone image. In this paper we introduce a new digital halftoning method based on maze generation algorithm as a replacement algorithm of halftoning with space-filling curve. Previous error-diffusion methods based on space-filling curve suffer from regular pattern artifacts from uniform scan pattern. We use maze generation algorithm to remove this undesirable pattern of space-filling curve method.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.733-738
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• 2008

Serial Music, introduced by A. Sch nberg, is a one of the important composition techniques. This music style has features of pantonality and atonality, so it generates unique atmosphere of modern music. In this paper, we introduce an method of generating serial music using mathematical algorithm. This method generates music that satisfy the requirement that the number of pitches belonged to each pitch class are exactly same, though the requirement is less strict than Sch nberg's definition. To do this, our method uses space-filling curves traversing the twelve tone matrix, which is constructed by the serial series, its inversion and its transpose. Using these curves, we can generate a music that has all notes in the matrix exactly once and adequate repeatness because of the curve's locality. Result music, therefore, can be more suitable for people that are not familiar with modern music, while maintaining the features of pantonality and atonality. This paper also introduces a method of generating extended serial music that uses serialism of duration and dynamic of notes, using multi-dimensional space-filling curves.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.23-30
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• 2004

In order to approximate the spatial query result size we partition the input rectangles into subsets and estimate the query result size based on the partitioned spatial area. In this paper we examine query result size estimation in skewed data. We examine the existing spatial partitioning techniques such as equi-area and equi-count partitioning, which are analogous to the equi-width and equi-height histograms used in relational databases, and examine the other partitioning techniques based on spatial indexing. In this paper we propose a new spatial partitioning technique based on the Hilbert space filling curve. We present a detailed experimental evaluation comparing the proposed technique and the existing techniques using synthetic as well as real-life datasets. The experiments showed that the proposed partitioning technique based on the Hilbert space filling curve achieves better query result size estimation than the existing techniques for space query size, bucket numbers, skewed data, and spatial data size.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.799-812
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• 2017

Backfill grouting and realistic convergence distribution were not properly considered in previous studies on 2D numerical analysis of a shield TBM tunnel. In this study, a modeling method was suggested to cope with this problem by considering a realistic convergence distribution and proper properties of backfill grouting. To this end, the influence of gap parameter and depth of rock cover on volume loss and composed of ground volume loss around tunnel excavation and surface volume loss were analyzed with a single layer of weathered soil. As a result, most of surface settlements were occurred immediately after excavation. Additional, as depth of rock cover and gap parameter increased, the influence range of surface settlement curves obtained from 2D numerical analyses became broader than a suggested theoretical equation. Therefore, it is inferred that gap parameter should be applied based on load distribution ratio and the property of backfill grouting properly considered for the estimation of the precise behavior of a shield TBM tunnel in 2D numerical analysis.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06c
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• pp.185-190
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• 2010

최근 위치 인식 기술과 휴대 장치의 발달로 인해 이동하는 객체를 기반으로 하는 위치 기반 서비스(Location Based Service, LBS)의 관심이 점점 증가하고 있고 그에 관련된 연구들이 활발하게 진행되고 있다. 이동 객체의 응용은 빈번하게 변경되는 이동객체의 위치정보를 효과적으로 처리할 수 있는 색인구조를 필요로 한다. 위치정보를 색인하기 위해 R-tree 기반의 색인들이 제안되었다. 하지만 R-tree는 변경보다는 검색 연산에 초점이 맞추어진 색인구조이기 때문에 잦은 변경을 다루어야 하는 이동객체 환경에 적합하지 못하다. 최근 이러한 객체의 빠른 위치 변경을 지원하는 그리드 기반의 색인 구조가 제안되었다. 하지만 셀의 객체 점유율에 따라 검색 속도가 저하되는 단점은 여전히 해결되지 못하고 있다. 이러한 단점은 객체들이 특정 영역에 몰리는 경우 또는 그리드의 해상도를 잘못 지정한 경우 더욱 부각된다. 본 논문에서는 이러한 단점을 해결하기 위해 가상 셀 기반의 색인 구조를 제안한다. 데이터 페이지에 객체의 점유율을 보장하기 위해 여러 개의 인접한 셀들의 데이터를 한 데이터 페이지에 함께 저장한다. 공간 채움 곡선을 기반으로 순서화된 셀들로 셀의 인접성을 결정한다. 또한 공간 채움 곡선의 차수를 동적으로 지정하여 객체가 집중된 셀에 대해서는 셀의 단위 크기를 작게 지정한다. 뿐만 아니라 셀을 표현하기 위한 식별자를 위해 비트를 이용한 표현식을 제안하였다. 이로 인해 노드의 팬아웃을 증가시켰고, 저장공간을 절약하였다. 실험을 통해서 제안하는 색인 기법의 우수성을 증명하였다.

• Journal of KIISE:Databases
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• v.32 no.4
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• pp.345-361
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• 2005

A transform-space index indexes objects represented as points in the transform space An advantage of a transform-space index is that optimization of join algorithms using these indexes becomes relatively simple. However, the disadvantage is that these algorithms cannot be applied to original-space indexes such as the R-tree. As a way of overcoming this disadvantages, the authors earlier proposed the transform-space view join algorithm that joins two original- space indexes in the transform space through the notion of the transform-space view. A transform-space view is a virtual transform-space index that allows us to perform join in the transform space using original-space indexes. In a transform-space view join algorithm, the order of accessing disk pages -for which various space filling curves could be used -makes a significant impact on the performance of joins. In this paper, we Propose a new space filling curve called the adaptive row major order (ARM order). The ARM order adaptively controls the order of accessing pages and significantly reduces the one-pass buffer size (the minimum buffer size required for guaranteeing one disk access per page) and the number of disk accesses for a given buffer size. Through analysis and experiments, we verify the excellence of the ARM order when used with the transform-space view join. The transform-space view join with the ARM order always outperforms existing ones in terms of both measures used: the one-pass buffer size and the number of disk accesses for a given buffer size. Compared to other conventional space filling curves used with the transform-space view join, it reduces the one-pass buffer size by up to 21.3 times and the number of disk accesses by up to $74.6\%$. In addition, compared to existing spatial join algorithms that use R-trees in the original space, it reduces the one-pass buffer size by up to 15.7 times and the number of disk accesses by up to $65.3\%$.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.241-243
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• 2001

이동 컴퓨팅 환경에서 이동 호스트의 위치가 변함에 따라 그 의미가 달라지는 위치 의존 질의를 효과적으로 처리하기 위해서는 이동 호스트의 캐시 기법이 중요하지만, 위치 의존 질의를 효과적으로 지원할 수 있는 지구국의 브로드캐스팅 기법도 중요하다. 본 논문에서는 지구국이 담당하는 영역을 격자로 나누어 인덱싱한 데이터를 위치 의존 질의에 적합하도록 공간-채움 곡선을 이용해서 선형 클러스터링하여 구성 시간을 줄이는 브로드캐스팅 기법을 제안하고, 구성 시간을 포함시킨 이동 호스트의 활동 시간을 측정하여 그 성능을 비교한다.

• Journal of Information Technology and Architecture
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• v.10 no.1
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• pp.79-91
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• 2013

This paper proposes a systematic methodology that could be used to decide which one shows the best performance among space filling curves (SFCs) in applying lower-dimensional transformations to histogram sequences. A histogram sequence represents a time-series converted from an image by the given SFC. Due to the high-dimensionality nature, histogram sequences are very difficult to be stored and searched in their original form. To solve this problem, we generally use lower-dimensional transformations, which produce lower bounds among high dimensional sequences, but the tightness of those lower-bounds is highly affected by the types of SFC. In this paper, we attack a challenging problem of evaluating which SFC shows the better performance when we apply the lower-dimensional transformation to histogram sequences. For this, we first present a concept of spatial locality, which comes from an intuition of "if the entries are adjacent in a histogram sequence, their corresponding cells should also be adjacent in its original image." We also propose spatial locality preservation metric (slpm in short) that quantitatively evaluates spatial locality and present its formal computation method. We then evaluate five SFCs from the perspective of slpm and verify that this evaluation result concurs with the performance evaluation of lower-dimensional transformations in real image matching. Finally, we perform k-NN (k-nearest neighbors) search based on lower-dimensional transformations and validate accuracy of the proposed slpm by providing that the Hilbert-order with the highest slpm also shows the best performance in k-NN search.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.1
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• pp.61-74
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• 2016

This paper presents a case study on the ground settlement and volume loss estimation for slurry pressure balanced shield TBM tunnelling in weathered zone of granite rock. Settlement at each stage of shield tunnelling was analyzed and the volume losses and settlement trough factors were estimated from observations. In addition, using the existing volume loss evaluation method in literature, volume losses were estimated considering ground properties and actual driving parameters. Most of ground settlement occurred during passage of shield skin passage and after backfill grouting, and the measured total volume loss and trough curves appeared to coincide with literature. Shield and tail loss obtained from field measurement were found to be around 90% and 60% of the predictions, where tail loss indicated larger deviation than shield loss.