• 한국정보처리학회논문지
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• 제4권4호
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• pp.895-907
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• 1997

연관규칙(asscociation rule) 탐사(mining)는 대용량 데이타베이스로부터 사건간의 동시 발생 경향을 발견하는 작업이다. 기존의 연관규칙은 전체 트랜잭션에 대하여 성립하는 사건 간의 연관 관계만을 고려하고 있다. 그러나 어떤 연관규칙은 비록 전체 시간구간에 대해서는 신뢰도가 그리 높지 않더라도 특징 기간에서 특별히 강한 신뢰도로 성립할 수 있고, 이러한 정보를 알 수 있다면 의사 결정에 매우 유용하리라고 생각한다. 본 논문 에서는 임의의 부분 시간구간에서 특별히 높은 신뢰도를 갖는 연관성을 한시적 연관규칙(transient assosiation rule)이라 정의하고, 대용량의 데이타베이스로부터 한시적 연관규칙이 성립하는 시간구간을 탐사하는 효율적인 알고리즘을 제안한다. 제안된 알고리즘은 불필요한 구간 검색을 배제할 수 있는 데이타 주도(data-driven) 검색 기법을 제시하고, 한 번의 데이타베이스 스캐닝(scaning)으로 다음 단계의 검색에 필요한 정보를 획득하여 주기억장치 상에 관리할 수 있도록 하는 효과적인 자료구조를 설계한다. 아울러 실험을 통해, 제안 알고리즘이 현장에 적용할 만한 시간 비용으로 수행됨을 보인다.

• 정보처리학회논문지A
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• 제11A권2호
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• pp.129-142
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• 2004

인터넷 회선의 고속화에 따라 패킷을 초당 기가비트 이상의 속도로 전송하는 라우터에 대한 연구가 활발하다. 본 논문에서는 라우터의 병목인 최장 프리픽스 검색(LPM : longest prefix matching)을 효율적으로 수행하기 위해 제안된 비트맵 트라이(Bitmap Trie) 알고리즘을 혁신적으로 향상시킨 방법을 제시한다. 이 방법은 검색시간을 단축하기 위하여 다음과 같은 세 가지 기법을 적용하였다. 첫째, 카운트 테이블을 추가하여 기존 알고리즘에서의 과도한 시프트 연산을 제거하여 프로세서 내의 처리시간을 단축했다. 두 번째는 트랜스퍼 테이블내의 중복된 포워딩 정보를 제거하여 메모리 효율을 증가시켰으며, 마지막으로, 포워딩 정보에 대한 접근빈도에 따라 검색범위를 다원화하여 데이터 접근을 최적화하였다. 또한, 신뢰도가 가장 놀은 실행-구동 시뮬레이션 방법을 채택함으로써 검색의 지연요소를 발생 원인별로 세분하여 알고리즘이 실행되는 과정을 면밀하게 분석할 수 있었다. 실험 결과는 실제 시스템으로부터 실측한 결과와 비교하는 검증과정을 거쳤으며, 그 결과 기존 알고리즘에 비해 검색 수행시간을 약 82% 단축한 알고리즘을 개발하였다.

• 한국생산제조학회지
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• 제19권6호
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• pp.812-828
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• 2010

A fuel injection system using an ECU HILS as an alternate to a vehicle test for the fuel injectors was developed. The throttle position, vehicle speed, engine speed, crank position, cam position, intake air flow, and several other sensor signals that are supplied to the ECU were measured and recorded as a data file for a vehicle driven in the FTP-75 mode in a chassis dynamometer. Electric signals that are equivalent to the sensor signals from the vehicle are reconstructed from the recorded data file using data acquisition boards, microprocessors, and computers. All sensor signals are supplied to the ECU with synchronized timing using a computer program. The findings show that the cost and time of vehicle experiments can be reduced using the ECU HILS system. Moreover, the repeatability of the generation of sensor signals can enhance the accuracy of a range of experiment related to vehicle testing. An ECU scanner that scans the sensor signals that are input to the ECU through a serial port was used to assess the accuracy of the reconstructed signals. The scanning results show good agreement with the reconstructed input signals. Injectors were connected to the ECU HILS system and were driven by the system to measure the quantity of injected fuel.

• Smart Structures and Systems
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• 제30권1호
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• pp.35-47
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• 2022

Data-driven engineering is crucial for information delivery between design, fabrication, assembly, and maintenance of prefabricated structures. Design for manufacturing and assembly (DfMA) is a critical methodology for prefabricated bridge structures. In this study, a novel concept of digital engineering model that combined existing knowledge of DfMA with object-oriented parametric modeling technologies was developed. Three-dimensional (3D) geometry models and their data models for each phase of a construction project were defined for information delivery. Digital design models were used for conceptual design, including aesthetic consideration and possible variation during fabrication and assembly. The seismic performance of a bridge pier was evaluated by linking the design parameters to the calculated moment-curvature curves. Control parameters were selected to consider the tolerance control and revision of the digital models. Digitalized fabrication of the prefabricated members was realized using the digital fabrication model with G-code for a concrete printer or a robot. The fabrication error was evaluated and the design digital models were updated. The revised fabrication models were used in the preassembly simulation to guarantee constructability. For the maintenance of the bridge, the as-built information was defined for the prefabricated bridge piers. The results of this process revealed that data-driven information delivery is crucial for lifecycle management of prefabricated bridge piers.

• 한국정보과학회논문지:시스템및이론
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• 제33권7호
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• pp.429-439
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• 2006

데스크탑 그리드는 컴퓨팅 집약적인 분산 어플리케이션을 수행하는데 있어서 유망한 플랫폼으로 부각되고 있다. 그러나 비 신뢰적이고 예측할 수 없는 자원의 특성 때문에 데스크탑 그리드에서 병렬 어플리케이션의 효율적인 스케줄링은 어려운 문제로 알려져 있다. 이에 따라서 빈약한 스케줄링 능력과 함께 현재 데스크탑 그리드는 고 처리 어플리케이션(high throughput application)의 실행에는 적합하지만 빠른 반환 시간을 요구하는 어플리케이션의 실행을 지원하는데 있어서 어려움을 갖는다. 빠른 반환 시간을 요구하는 어플리케이션의 효율적인 실행은 어플리케이션의 전체 실행 시간(makespan)을 축소함으로써 해결할 수 있는 문제로써 데스크탑 그리드가 이를 지원할 수 있게 하는 것은 매력적인 제안이 될 것이다. 본 논문에서는 데스크탑 그리드에서 효율적인 어플리케이션의 실행을 지원하기 위한 새로운 스케줄링 방법을 제안한다. 7주간의 시간동안 40대의 데스크탑에서 추출된 추적(trace) 데이타의 분석을 통해서 데스크탑 사용 경향성과 비 신뢰적인 데스크탑의 영향이 스케줄링의 성능을 개선하는데 있어서 활용 될 수 있음을 확인하였고 이 요소들을 고려함으로써 데스크탑 그리드의 비 신뢰적이고 예측할 수 없는 자원의 특성을 스케줄링에 적절하게 반영 할 수 있는 스케줄링 기법이 제안되었다. 제안된 스케줄링 기법은 실제 데스크탑들의 행동 패턴을 반영한 추적 기반 시뮬레이션(trace-driven simulation)을 통해서 기존의 스케줄링 방법들과 스케줄링 성능이 비교되었고 시뮬레이션 결과를 통해서 제안된 스케줄링 기법이 기존의 데스크탑 스케줄링 기법들에 비해서 병렬 어플리케이션의 전체 실행 시간을 축소하고 중지(suspension)와 장애(failure)의 발생 빈도를 줄이는 것을 보여준다.

• 태양에너지
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• 제18권3호
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• pp.107-112
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• 1998

Basic design of a solar driven absorption cooling machine(SDACM) with a cooling capacity of 5 USRT was carried out. The SDACM is a single effect cycle driven by low temperature hot water from solar collectors. The SDACM design data were calculated by the steady state simulation program which was developed in this study The variation of COP and cooling capacity of the SDACM were investigated at different off-design conditions. Both the cooling capacity and the system COP were improved with decreasing cooling water temperature. If hot water temperature was increased, the cooling capacity was improved but the system COP was found to be decreased. The decrease of the system COP were basically caused by increased thermal loads in the system components.

• 대한전자공학회논문지
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• 제23권2호
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• pp.225-235
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• 1986

Dataflow computers exhibit a high degree of parallelism which can not be obtained easily with the conventional von-Neumann architecture. Since many instructions are ready for execution simultaneously, concurrency can easily by achieved by the multiple processors modified the data-flow machine. In paper, we describe an improved dataflow architecture which is designed by adding the demand propagation network to the MIT dataflow machine. and show the improved performance by the execution time and the efficiency of processing elements through simulation with the time acceleration method.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.143-151
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• 2001

During the past several years, the major interests of car manufacturers in development of automatic transmission were in durability and shift quality. However, a large number of researches for improving shift quality that are based on dynamic characteristics of shifting mechanism have been rarely adopted in the developing process because it is quite difficult to predict the shifting performance from the dynamics simulation. One of the important reasons for the difference between simulation results and experiments arises from the automatic transmission hydraulic system that consists of many valves with high order model and shows a lot different dynamics to temperature variation. In this work, hardware-in-the-loop simulation system for automatic transmission was developed f3r improving the accuracy of simulated result by combining the real-time simulation model with the real hydraulic system. The real-time simulation for automatic transmission model excluding hydraulic system is executed with TI's TMS320C31 DSP and the interfacing board which includes 12bit A/D, PWM signal generator and driver, serial driver ,etc is designed for acquiring the simulation data and signal interface with hydraulic system. We verified the proper operation and correctness of shifting result by comparing the off-line simulation result with that of HILS and experimental result which was performed on transmission dynamometer driven by electric motor.

• 한국정밀공학회지
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• 제8권4호
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• pp.84-94
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• 1991

In order to achieve high accuracy of teaching and increase productivity using industrial robots in polishing process of dies, an off-line task programming system was developed on IBM-PC/386 under WINDOWS 3.0 operating system. The internal structure and the machematical basis of CAMPoli are described. Surface modeling technique of polishing dies with sculptured surfaces is introduced by poing data interpolation methodology through the use of CL-data transmitted from conventional CAM system. Tool selection, polishing speed, polishing pressure and kinds of tool motions can be determined and selected by user specified polishing variables. Task creation and verification of polishing path via computer graphics simulation of polishing tool can be done by the menu- driven function of CAMPoli system. Post-processing module is attached to generate robot language. Some simulation results are provided as verification means of the system.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.311-317
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• 2005

It has been the most progressive interruption technique to use the ablation gas from the surface of PTFE nozzle driven by arc plasma during switching process in $SF_6$ gas circuit breakers. This advanced interruption technique can reduce the required mechanical energy to compress and blow the gas for extinguishing the arc plasma between the electrodes due to using the ablation effect instead. In order to consider the phenomena during calculation of switching process, it is required to confirm the principles of ablation from PTFE nozzle as well as of arc plasma during switching process. In this study, we have calculated the switching process considered the ablation of PTFE nozzle driven by arc plasma using multidisciplinary simulation technique and compared the results with the data without the ablation effect. More $50\%$ difference of pressure rise inside expansion chamber has been found from the results and it should be indispensable for this type of computational work to consider and include the ablation effect of PTFE nozzle. Further study on turbulence and radiation will be followed.