• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.699-702
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• 2012

본 논문에서는 WCDMA(Wide Code Division Multiple Access) 시스템 사양을 만족시키는 주파수 합성기 블록 중 위상잡음 및 전력소모의 최적 설계가 필요한 LC-VCO(voltage controlled oscillator)의 설계를 제안 하였다. 최적 설계를 위한 핵심내용은 LC-tank의 손실성분을 보상하는 MOS트랜지스터의 전달컨덕턴스와 인덕턴스 평면에 여유이득라인과 튜닝 범위 라인을 그어 설계 가능한 영역 내에서 위상잡음이 최소가 되는 인덕턴스 값을 구하고 선택하는 것이다. 제안한 최적 설계방법에 의해 진행된 LC-VCO의 시뮬레이션 결과 위상잡음 특성은 1MHz옵셋에서 -113dBc/Hz였다.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.580-584
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• 2017

본 논문에서는 얀센 메커니즘을 이용한 4족 보행 로봇의 설계와 라인 추적을 통해 목표지점까지 도달할 수 있도록 하는 센싱에 대해 보인다. 가장 핵심이라고 판단되는 구동부의 최적 설계를 위해 m.Sketch를 이용하여 GAC와 GL를 설정하였고, 최적 설계 후 다리 경량화를 통한 로봇 속도 개선 등의 문제는 차후에 다루기로 한다. 본 논문에서 언급되는 모든 구동부는 이론적 계산을 기초로 하여 CATIA 프로그램을 사용하여 제작되었으며, 과학상자를 이용한 여러 번의 구조변경 실험을 통해 최적의 설계를 찾는 것을 목표로 한다.

• The KIPS Transactions:PartD
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• v.13D no.4 s.107
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• pp.463-476
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• 2006

R-trees have been traditionally optimized for the I/O performance with the disk page as the tree node. Recently, researchers have proposed cache-conscious variations of R-trees optimized for the CPU cache performance in main memory environments, where the node size is several cache lines wide and more entries are packed in a node by compressing MBR keys. However, because there is a big difference between the node sizes of two types of R-trees, disk-optimized R-trees show poor cache performance while cache-optimized R-trees exhibit poor disk performance. In this paper, we propose a cache and disk optimized R-tree, called the PR-tree (Prefetching R-tree). For the cache performance, the node size of the PR-tree is wider than a cache line, and the prefetch instruction is used to reduce the number of cache misses. For the I/O performance, the nodes of the PR-tree are fitted into one disk page. We represent the detailed analysis of cache misses for range queries, and enumerate all the reasonable in-page leaf and nonleaf node sizes, and heights of in-page trees to figure out tree parameters for best cache and I/O performance. The PR-tree that we propose achieves better cache performance than the disk-optimized R-tree: a factor of 3.5-15.1 improvement for one-by-one insertions, 6.5-15.1 improvement for deletions, 1.3-1.9 improvement for range queries, and 2.7-9.7 improvement for k-nearest neighbor queries. All experimental results do not show notable declines of the I/O performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.11
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• pp.903-910
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• 2014

Electric fans, which consist of axial blades, are operated by the induction motor. In this paper, the objective of this study is the performance improvement of the base model fan using the design optimization. In order to aerodynamic analysis, computational simulations are performed using commercial tool ANSYS-CFX ver. 14.5. And k-${\omega}$ SST turbulence model is used for the CFD analysis. The design variables are set up as sweep and lean angles. Volumetric flow rate and torque of the fan blades are fixed to objective function. The optimized model is shown the increment of the volumetric flow rate and the reduction of the torque compared with the base model. The experimental procedure is followed KS C 9301. CFD results and experimental results are fairly well matched.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.115-120
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• 2014

Many product line engineering methods use the feature model to structure commonality and variability among products in terms of features and to derive a product feature configuration, which is the set of features required for the development of a product. Features to be selected during product derivation are mainly determined based on the quality attributes required for a product. Most methods published so far derived an optimal product feature configuration through linear co-relationship between features and quality attributes. However, the co-relationship between features and quality attributes can be formulated as a non-linear function because of feature interactions. This paper proposes a method that derives an optimal product feature configuration considering feature interactions. Four product line cases are used to validate the proposed methods.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.239-245
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• 2008

A level set based topological shape optimization using extended B-spline basis functions is developed for steady-state heat conduction problems. The only inside of complicated domain identified by the level set functions is taken into account in computation, so we can remove the effects of domain outside parts in heat conduction problem. The solution of Hamilton-Jacobi equation leads to an optimal shape according to the normal velocity field determined from the sensitivity analysis, minimizing a thermal compliance while satisfying a volume constraint. To obtain exact shape sensitivity, the precise normal and curvature of geometry need to be determined using the level set and B-spline basis functions. Using topological derivative concept, the nucleation of holes for topological changes can be made whenever and wherever necessary during the optimization.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.50-55
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• 2002

The standard approach of image resampling is to fit the original image with continuous model and resample the function at a desired rate. We used the B-spline function as the continuous model because it oscillates less than the others. The main purpose of this paper is the derivation of a nonuniform optimal resampling algorithm. To derive it, needing approximation can be computed in three steps: 1) determining the I-spline coefficients by matrix inverse process, 2) obtaining the transformed-spline coefficients by the optimal resampling algorithm derived from the orthogonal projection theorem, 3) converting of the result back into the signal domain by indirect B-spline transformation. With these methods, we can use B-spline in the non-uniform resampling, which is proved to be a good kernel in uniform resampling, and can also verify the applicability from our experiments.

• The Journal of the Korea Contents Association
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• v.19 no.12
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• pp.565-572
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• 2019

Optimization of production system of polyester manufacturing companies is an important task for strengthening the competitiveness of the domestic polyester industry. The purpose of this study is to present a way to evaluate the goodness of the polyester manufacturing systems determined by the combinations of production facilities and to derive the optimal configuration of the production system. To this end, the criteria or factors for the evaluating polyester production system were derived and the Analytic Hierarchy Process (AHP) was used. Using the AHP model, we derived weights on the criteria for evaluating polyester production system and drew priorities for the configurations of the production systems under consideration.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.241-248
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• 2022

A guideline for determining the optimal catheter length according to the patient's physique during tunnel-type dialysis catheter insertion used in renal failure patients is presented, and the maintenance of the function of the dialysis catheter is evaluated. From October 1, 2015 to February 31, 2016, a total of 110 (male : female = 73 : 37) patients who underwent tunnel-type dialysis catheterization performed at our hospital were treated without using guidelines. The group was divided into A group, and the group treated using the guideline into B group. Results were analyzed statistically using SPSS 20.0. As a result of the dialysis catheter insertion procedure according to the use of guidelines, the function maintenance rate of group A was 81.8%, and the function maintenance rate of group B was 96.3%. In the case of tunnel dialysis catheter procedure, the function maintenance effect was statistically significant in the group treated using the guideline compared to the group not using it (p<0.05). It can be said that it is more effective when information on the patient's underlying disease is reflected in addition to the use of guidelines.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.179-179
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• 1994