• 한국자동차공학회논문집
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• 제10권1호
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• pp.244-254
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• 2002

To enhance the acceleration performance and fuel consumption rate of a vehicle, the torque converter is modified or newly-developed with reliable analysis model. Up to recently, the one dimensional performance model has been used for the analysis and design of torque converter. The model is described with constant parameters based on the concept of mean flow path. When it is used in practice, some experiential correction factors are needed to minimize tole estimated error. These factors have poor physical meaning and cannot be applied confidently to the other specification of torque converter. In this study, the detail dynamic model of torque converter is presented to establish the physical meaning of correction factors. To verify the validity of model, performance test was carried out with various input speed and oil temperature. The effect of oil temperature on the performance is analysed, and it is applied to the dynamic model. And, to obtain the internal flow pattern of torque converter, CFD(Computational Fluid Dyanmics) analysis is carried out on three-dimensional turbulent flow. Correction factors are determined from the internal flow pattern, and their variation is presented with the speed ratio of torque converter. Finally, the sensitivity of correction factors to the speed ratio is studied for the case of changing capacity factor with maintaining torque ratio.

• 한국통신학회논문지
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• 제29권4B호
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• pp.435-443
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• 2004

RSVP는 강력한 Qos 보장 시그널링 프로토콜이기는 하지만 확장성에 문제점을 가지고 있기 때문에, IETF는 RSVP에 묶음 자원 예약 개념을 도입하였다. 그러나, 묶음 자원 예약에 관한 RSVP 규격은 경로에 대하여 예약되고 해제될 묶음 자원의 크기 계산 방법을 명시하지 않고, 묶음 자원의 크기가 주어진 경우에 자원을 예약하고 해제하는 절차에 대하여 서술하고 있다. 본 논문은 실시간 응용의 Qos 보장을 위하여 RSVP를 통해 묶음 단위로 자원을 예약하고 해제하고자 할 때, 경로의 상태에 적절하게 예약되고 해제될 묶음 자원의 크기 결정 방법을 제안한다. 시뮬레이션을 통하여 제안하는 방법을 적용하였을 때 묶음 단위 RSVP의 효율성이 향상됨을 보인다.

• 대한기계학회논문집
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• 제17권6호
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• pp.1330-1341
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• 1993

본 연구에서는 회전대우(revolute joint)들로 이루어진 1자유도 평면기구들의 특성을 파악하고 그래이프이론(graph theory)을 이용하여 기구의 형태를 행렬로 표시 하여 체이터베이스에 저장하였다. 또한 기구의 특성중의 하나인 작업조건(function specification)에 따른 무오차점(precision point)의 최대 개수를 알아내는 프로그램 을 개발하여 이로써 얻은 정보를 또 다른 데이타베이스에 저장하였다. 이와같이 구축 된 데이터베이스들로부터 설계자의 요구에 적합한 기구를 선택하여 형태합성 문제를 해결하였다.

• 한국정보통신학회논문지
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• 제10권11호
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• pp.1954-1959
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• 2006

본 논문에서는 WPAN 환경에서 IEEE 802.15.4a 규격을 활용한 TH UWB-IR 의료영상 전송 시스템을 제안하였다. 또한, 무선 의료영상 전송을 위해 ITU-R M.1225 다중경로 채널 모델을 이용하여 실내 다중경로 페이딩 환경에서의 송수신 성능을 분석하였다. 분석 결과, 제안한 방식은 동일 공간에서 사용되는 의료장비와의 간섭 영향에 관한 문제의 해결이 가능하고 실내 다중경로 페이딩 환경에서 의료영상의 손실을 최소화하면서 저 전력 전송이 가능함을 알 수 있었다.

• 한국정보통신학회논문지
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• 제26권10호
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• pp.1537-1544
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• 2022

application specific integrated circuit (ASIC) 및 system on chip (SoC) 설계 시 디지털 회로는 클럭에 동기화되어 작동한다. 칩 설계 시, place & route (P&R)에서 설계 조건과 타이밍 조건, 클럭의 동기화 여부 등을 고려한다. P&R에서 클럭 경로에 대한 delay를 줄이기 위해, clock tree synthesis (CTS) 기법을 이용한다. 본 논문에서는 사전 클럭트리 합성 가능 여부 판단을 위한 shallow-CTS 알고리즘을 소개한다. 오픈 소스 Parser-Verilog를 사용하여 register transfer level (RTL) 합성가능한 Verilog를 파싱하여, Pre-CTS와 Post-CTS 단계를 진행하고, 가장 긴 clock path와 버퍼 삽입 전후의 표준편차를 비교하여 CTS의 정확도에 대해 분석한다. 본 논문에서 시간 투입이 많이 되는 licensed EDA tool을 사용하여 CTS 결과를 확인하지 않고, RTL 수준에서 사전 클럭 트리 합성 검증 방법을 제공하여 비용 및 시간문제를 감소할 수 있을 것으로 기대된다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.284-289
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• 2002

In this paper, we develop a six-axes machining center tool(MCT) and CAD/CAM system based RAD Tool Program. The MCT consists of two mechanical parts, i.e., a X-Y-Z Cartesian coordinate typed MCT and a parallel-typed tilting table. Kinematics and singularity are accomplished to design the parallel-typed tilting table, and RAD Tool Program Is developed for the six-axes MCT, which requires the commands of position as well as orientation for machining of complex shape. In RAD Tool, the CAD/CAM system has a tool path generator, NC code generator and a graphic simulator. This paper designs the parallel-typed tilting table to meet the desired specification and presents the results of CAD/CAM system based RAD Tool Program.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1245-1248
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• 1996

This paper describes a cell programming environment that deals with problems associated with programming Flexible Manufacturing Cells(FMCs). The environment consists of the cell programming editor and the automatic generation module. In the cell programming editor, cell programmers can develop cell programs using task level description set which supports task-oriented specifications for manipulation cell activities. This approach to cell programming reduces the amount of details that cell programmers need to consider and allows them to concentrate on the most important aspects of the task at hand. The automatic generation module is used to transform task specifications into executable programs used by cell constituents. This module is based on efficient algorithm and expert systems which can be used for optimal path planning of robot operations and optimal machining parameters of machine tool operations. The development tool in designing the environment is an object-oriented approach which provides a simple to use and intuitive user interface, and allows for an easy development of object models associated with the environment.

• International Journal of Concrete Structures and Materials
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• 제10권1호
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• pp.1-13
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• 2016

The progressive collapse analysis of reinforced concrete (RC) moment-frame buildings under extreme loads is discussed from the perspective of modeling issues. A threat-independent approach or the alternate path method forms the basis of the simulations wherein the extreme event is modeled via column removal scenarios. Using a prototype RC frame building, issues and considerations in constitutive modeling of materials, options in modeling the structural elements and specification of gravity loads are discussed with the goal of achieving consistent models that can be used in collapse scenarios involving successive loss of load-bearing columns at the lowest level of the building. The role of the floor slabs in mobilizing catenary action and influencing the progressive collapse response is also highlighted. Finally, an energy-based approach for identifying the proximity to collapse of regular multi-story buildings is proposed.

• 대한기계학회논문집
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• 제14권2호
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• pp.376-381
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• 1990

An interactive computer program to design a mold cavity with the proper rigging system has been developed. In addition to the pattern and the risers generated in part 1 of this work, the various components of the gating system are generated in complete three dimensional models by a rational approach. Then they are laid interactively by the user, and united together with the pattern and the risers to result in the three dimensional model of the mold assembly. Finally, the vents and the mold box are constructed following the user's interactive specification and then the mold cavity is completed in a three dimensional geometric model by subtraction the mold assembly and the vents from the mold box. The three dimensional model of a mold cavity is useful for many related applications such as the solidification simulation for mold evaluation and the NC tool path generation for mold production.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.205-208
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• 2001

According to the IMT-2000 specification of 3GPP(3rd Generation Partnership Project) and 3GPP2, Turbo codes is selected as a FEC(forward error correction) code for even higher reliable data communication. In 3GPP complied IMT-2000 system, channel coding under consideration is the selective use of convolutional coding and Turbo codes of 1/3 code rate with 4 constraint length. Suggesting a new path metric normalization method, we achieved a low complexity and high performance SOVA decoder for Turbo Codes, Further more, we analyze the decoding performance with respect to update depth and find out the optimal value of it by using computer simulation. Based on the simulation result, we designed a SOVA decoder using VHDL and implemented it into the Altera EPF10K100GC503FPGA.