• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.742-744
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• 2004

본 논문에서는 표준 셀 배치기 Mongrel의 성능을 개선하기 위해 사용된 다양한 기법에 관해 살펴보고 top-down방식의 계층적 분할 기법을 이용한 광역 배치(Hierarchical Global Placement)를 제안한다. 계층적 분할 기법을 이용한 광역 배치는 RBLS(Relaxation Based Local Search) 기법과 더불어 Mongrel의 성능 개선에 결정적인 역할을 하고 있으며 분할 기법으로 hMETIS(클러스터링을 이용한 다단계 분할 기법)를 사용한다. 우리는 표준 벤치마크 회로를 이용한 실험을 통해 계층적 분할 기법을 이용한 광역 배치 기법이 안정적이면서 효율적인 배치 결과를 가져옴을 보인다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.12
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• pp.61-70
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• 2005

In this paper, we propose an efficient global placement algorithm which is an enhanced version of Hybrid Placer$^{[25]}$, a standard cell placement tool, which uses a middle-down approach. Combining techniques used in the well-known partitioner hMETIS and the RBLS(Relaxation Based Local Search) in Hybrid Placer improves the quality of global placements. Partitioning techniques of hMETIS is applied in a top-down manner and RBLS is used in each level of the top-down hierarchy to improve the global placement. The proposed new approach resolves the problem that Hybrid Placer seriously depends on initial placements and it speeds up without deteriorating the placement quality. Experimental results prove that solutions generated by the proposed method on the MCNC benchmarks are comparable to those by FengShui which is a well known placement tool. Compared to the results of the original Hybrid Placer, new method is 5 times faster on average and shows improvement on bigger circuits.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.6 s.348
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• pp.23-29
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• 2006

In this paper, we propose an effective global placement technique using quadratic programming(QP). In order to resolve cell congestion problem which is a drawback of QP based placement techniques, additional force and grid pre-warping technique are used. We devised a new density function for evaluating proper additional force which depends on density. Grid pre-warping technique relocates cells over entire area according to the relative ordering between coordinates of cells. Using the additional force obtained by the new density function and applying the pre-warping technique iteratively we obtained a well-distributed global placement. Mongrel which is a middle-down methodology based placer takes such a good global placement as an initial placement and produces a final detailed placement. Experimental results show that proposed technique outperforms the FM algorithm based global placement and are comparable with the well-known leading placers, FengShui, Dragon.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.10
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• pp.595-602
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• 2003

This Paper presents an efficient hybrid techniques for a standard cell placement. The prototype tool adopts a middle-down methodology in which an n${\times}$m grid is imposed over the layout area and cells are assigned to bins forming a global placement. The optimization technique applied in this phase is based on the Relaxation-Based Local Search (RBLS) framework [12］in which a combinatorial search mechanism is driven by an analytical engine. This enables a more global view of the problem and results in complex modifications of the placement in a single search“move.”Details of this approach including a novel placement legalization procedure are presented. When a global placement converges, a detailed placement is formed and further optimized by the optimal interleaving technique[13］. Experimental results on MCNC benchmarking circuits are presented and compared with the Feng Shui's results in［14］. Solution Qualifies are almost the same as the Feng Shui's results.

• The Journal of Sustainable Design and Educational Environment Research
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• v.16 no.3
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• pp.27-36
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• 2017

The purpose of this study is to provide a basis for determining when a school established long term school plans accepted by analyzing the trend of increase or decrease elementary school students 30 years to target of following city, 323 elementary schools in Busan - 16 administration zone for this purpose. Results of this study are as follows: First, type 5 occupies 55.4% of the total, followed by the second most, type 10, 21.4%> type 11> type 13> type 15, which is the most urgent object of the student placement plan Can be. Second, the results of the Conflict Model I and Conflict Model II showed that Type1 and Type7 were not needed to be adopted. Third, we can see through the case analysis that the effect of excessive school opening on the decrease of the number of students in the nearby school is serious. Fourth, as a result of analyzing the current number of students in Busan, the number of schools with less than 150 students accounted for 12.4% of the total 323 elementary schools, 30.0% for schools with less than 300 students, and 60.4% for students with less than 600 students. Fifth, when the elementary school student induction rate of urban redevelopment area in Busan was examined, the average induction rate was 0.37.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.1_2
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• pp.92-104
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• 2006

The proposed method for a force directed global placement algorithm exploits and extends techniques from two leading placers, Kraftwerk (& KraftwerkNC) and Mongrel. It combines the strengths of KraftwerkNC, force directed global placer, and Mongrel's ripple move technique which resolves cell overlaps effectively The proposed technique uses the force spreading technique used in Kraftwerk to optimize the ripple movement. While it is resolving the cell overlap and optimizing wire length physical net constraints are considered for timing. The experimental results obtained by the proposed approach shows significant improvement on wire length as well as on timing.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.4
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• pp.431-435
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• 2008

Since previous work CDP(Congestion Driven Placement) [1] considers all possible directions to move every cell in nets which contribute highly to routing congestion, it consumes CPU time a lot. In this paper, we propose a faster global placement technique, so called ICDGP(Improved Congestion Driven Global Placement) to relieve the routing congestion. ICDGP uses the force-directed method to determine the target locations of the cells in the nets in the congested spots, and considers only to move the target location for each cell. If moving multiple cells simultaneously is considered better than moving each cell one by one it moves multiple cells simultaneously. By experimental results, ICDGP produces less congested placement than CDP does. Particularly, the CPU time is reduced by 36% on average.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11a
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• pp.339-342
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• 2003

배치는 칩의 성능 및 레이아웃에 결정적인 영향을 주는 요인으로써 크게 광역배치와 상세배치 두단계를 거쳐 이루어지며 수년 동안 다양한 기법들이 개발되어 왔다. 본 논문에서는 표준 셀 배치를 개선하기 위한 동적 프로그래밍 기법을 이용한 최적 인터리빙 알고리즘을 확장하여 선을 동일 행 내에서만 움직이던 한계점을 극복하여 서로 다른 행 사이에서도 움직일 수 있도록 하였다. 즉, 셀들은 주어진 배치 내에서 임의의 위치로 움직일 수 있어 배치가 더욱 효율적으로 최적화 될 수 있도록 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11a
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• pp.517-520
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• 2002

YLSI 칩 설계에서 물리 설계의 과정은 칩의 크기나 성능 그리고 칩 생산수율 등에 결정적인 영향을 미치는 매우 중요한 단계로써 이 자체가 매우 복잡하기 때문에 또 여러 세부 단계로 나누어 물리 설계가 수행된다. 그러므로 물리 설계를 위한 많은 연구가 계속되어 왔고 그 중 배치를 위한 연구도 20여년 이상 되어 왔다. 좋은 배치를 얻기 위해 크게 두 단계, 즉 광역배치(global placement)와 미세배치(detailed placement) 단계로 나누어 수행되는데 본 논문에서는 미세 배치를 매우 효과적으로 개선할 수 있는 동적 프로그래밍 기법을 이용한 효율적인 알고리즘을 제시하며 실험 결과를 통하여 제시된 알고리즘의 효율성을 입증하였다. 최근의 최신 배치프로그램을 통해 얻은 결과에 본 논문에서 제시한 알고리즘을 적용했을 경우 HP(half perimeter)가 평균 3.4% 정도 개선되었다.

• Journal of Korean Library and Information Science Society
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• v.38 no.1
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• pp.173-194
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• 2007

The purpose of this paper is to make understanding on the influence of school librarian on students' reading behavior. The Writer has collected and analysed data from 2,865 students in Daegu Metropolitan City according to statistical method and process. In conclusion, the writer proved school librarian give much developmental influence on students' reading behavior.