• The Journal of Society for e-Business Studies
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• v.19 no.1
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• pp.131-143
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• 2014

A triple database consisting of a number of three-column tables require high cost of query processing, whereby building a shortcut is known as an effective way to reduce the cost. It is important to figure out what shortcuts needs to be selectively built. Most shortcut selection algorithms make use of a benefit model that considers the query frequency. However they work poor to reflect the database update. In this paper, we consider a benefit model for triple databases. The model considers not only the profit of query response times but also the building and maintenance costs of the shortcuts. We apply the model to design a benefit function which can be plugged in a greedy-based shortcut selection algorithm. We perform the empirical experiments on a real-world dataset and analyze the effect of each factor employed in the benefit function.

• The KIPS Transactions:PartD
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• v.11D no.7 s.96
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• pp.1409-1416
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• 2004

Recently, due to the popularity and explosive growth of the Internet, information exchange is increasing dramatically over the Internet. Also the XML is becoming a standard as well as a major tool of data exchange on the Internet. so that in retrieving the XML document. the problem for speeding up evaluation of path-oriented queries is a main issue. In this paper, we propose a new indexing technique to advance the searching performance of path-oriented queries in document databases. In the new indexing technique, an abbreviation-path file to perform path-oriented queries efficiently is generated which is able to use its hash-code value to index keys. Also this technique can be further enhanced by combining the Extendible Hashing technique with the abbreviation path file to expedite a speed up evaluation of retrieval.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2D
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• pp.193-201
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• 2011

The provision of traffic information plays an important role in increasing social benefit not only by saving travel time for individuals but also by improving the efficiency of road operation. VMS(Variable Message Sign) helps on-wheel drivers easily understand the road situation, and also provides real-time traffic information to people on the streets. However, it has not been sufficiently studied on how traffic information based on VMS influences on the drivers' selection of route. This study investigated how drivers use VMS traffic information and how they are satisfied with it. Then, the model of drivers' route selection was specified with the types of traffic information and the expected travel time to examine the influence on the selection of drivers' route. The model was estimated and analyzed in three types according to the condition of detour roads, and the rate of route change and the degree of sensitivity was calculated from the estimation. The results of analysis are as follows. the $1^{st}$ type model showed the 10% of route change for the travel time saving of 5minutes, and the 81.6% of route change for the travel time saving of 20minutes. The $2^{nd}$ type led to the range of route change from 14.2% to 92.7% over the 5 through 20 minutes of travel time saving. The $3^{rd}$ model resulted in the 99.1% of route change. The sensitivity of route change showed the highest for the travel time saving of 11 minutes with the $1^{st}$ type model, 9 minutes with the $2^{nd}$ type model, and 5 minutes with the $3^{rd}$ type model respectively.

• Journal of the Korea Convergence Society
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• v.10 no.9
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• pp.17-22
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• 2019

Gentry, an SMT equipment, is a device that absorbs electronic components from the feeder and mounts them correctly on the PCB. At this time, the gantry stops in front of the camera to check whether the parts are correctly adsorbed. In this paper, we propose a method to shorten the moving time by moving the gantry without stopping in front of the camera. This method shows that the moving time is shorter than that of the conventional method by finding a path that can be moved in the fastest time among the various moving paths. The proposed method (moving-motion) reduces the gantry travel time by 20% compared to the conventional method (stop-motion).

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.10a
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• pp.163-169
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• 1997

본 논문에서는 평균 차량속도를 향상시키고 평균 차량대기시간을 줄이는 새로운 최적 교통신호주기산출방법을 제안한다. 전자교통신호등은 차량은 교차로에 많을때에는 교통신호주기을 연장 할 수 있고 교차로에 차량이 적을 경우에는 교통신호주기를 단축할 수 있다. 그러나 요즈음과 같이 교통체증이 많아서 평균주행속도가 10km - 20km 로 서행우전할 수 밖에 없을때에는 전자신호등의 기능을 수행할 수 없다. 그러므로 본 논문에서는 승용차대기시간을 단축하기위해서 최적 경로 알고리즘을 사용하여 목적지까지 가장 빠르게 도착할 수 있는 교통신호설계 소프트웨어 Tool을 개발하였다. 컴퓨터 모의실험결과 G.P.S.를 자동차에 내장하여 최단경로선택을 하는 차량이 기존의 최적경로선택기능이 없는 차량보다 승용타대기시간 및 평균주행속도가 10% - 32% 가량 개선시킬 수 있음을 입증하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.929-932
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• 2004

DRACO 구조는 이중 링 연결형태에 대비하여 노드간 접근 경로를 단축할 수 있는 구조로, CC-NUMA 시스템에 대하여 그 적용성과 프로토콜이 시험되어 그 효율성이 입증되었다. 본 논문은 이러한 DRACO 구조가 보다 많은 프로세서를 수용할 수 있는 클러스터 시스템에 대하여 동일한 경로 단축과 대역폭 확장을 적용할 수 있음에 기반하여, 이중 연결 링크를 가지고 있는 점대 점 연결 형태의 클러스터 시스템에 대한 적용성을 연구하였다. 노드 내의 네트워크 인터페이스 및 소프트웨어만을 이용한 DRACO 구조 적용은 많은 수의 노드를 필요로 하는 시스템에 적합하고, 하드웨어를 이용한 연결 경로를 이용할 경우 상대적으로 적은 수의 노드를 채용하고 고속의 링크 성능을 필요로 하는 시스템에 적합할 것이다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1809-1810
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• 2008

자율이동로봇의 동특성을 고려하여 실용적인 경로를 생성하는 방법을 제안한다. 목표 지점까지 장애물을 회피하고, 자율이동로봇의 속도 및 조향각 등을 고려하여, 최적에 가까운 경로를 생성하는 방법을 다룬다. 본 논문에서 골격선 그래프를 구성하여 딕스트라알고리즘으로 초기 전역 경로를 설정하고, 이를 로봇의 동특성을 고려하여 동적 프로그래밍을 통해 경로를 개선한다. 개선된 경로는 자율이동로봇이 이동하는데 걸리는 시간을 단축한다. 마지막으로 시뮬레이션을 통해 제안하는 방법의 성능을 검증한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.581-590
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• 2003

This paper proposes the routing path selection mechanism for source routing-based PtMP (Point-to-Multipoint) call in ATM switching system. Especially, it suggests PtMP routing path selection method that can share the maximum resource prior to the optimal path selection, guarantee the reduction of path calculation time and cycle prevention. The searching for the nearest branch point from destination node to make the maximum share of resource is the purpose of this algorithm. Therefore among neighbor nodes from destination node by back-tracking, this algorithm fixes the node crossing first the node on existing path having the same Call ID as branch node, constructs the optimal PtMP routing path. The optimal node to be selected by back-tracking is selected by the use of Dijkstra algorithm. That is to say, PtMP routing path selection performs the step of cross node selection among neighboring nodes by back-tracking and the step of optimal node selection(optimal path calculation) among neighboring nodes by back-tracking. This technique reduces the process of search of routing information table for path selection and path calculation, also solves the cycle prevention easily during path establishment.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.355-356
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• 2008

자율이동로봇의 기구학 및 동력학 모델을 통해 로봇의 특성을 고려하여 목표점까지 이동시간이 최소화 되는 경로 생성 방법을 제안한다. 본 논문에서는 초기 전역 경로를 골격선 그래프와 딕스트라알고리즘으로 설정하고, 로봇 기구학 및 동력학 제악조건을 고려하여 동적 프로그래밍으로 경로를 개선한다. 개선된 경로는 자율이동로봇이 이동하는데 걸리는 시간을 단축한다. 마지막으로 시뮬레이션을 통해 제안하는 방법의 성능을 검증한다.

• Journal of the Korea Convergence Society
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• v.10 no.4
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• pp.39-43
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• 2019

The gantry of surface mount equipment (SMD) is responsible for transferring parts from the feeder to the PCB. At this time, the moving time of the gantry affects the yield. Therefore, in this paper, we propose the fastest path from the suction to the mounting to reduce the gantry travel time. This path is a case where the velocity in front of the camera is 2m/sec due to the nature of the gantry. Therefore, the trajectory graph of this case was created through simulation and the travel time was calculated. As a result, we can see that the moving time of the moving-motion method proposed in this paper is 20% shorter than the current stop-motion method.