Tire Blocked Force Simulation 개발 및 민감도 연구 사례

김현욱(Hyunuk Kim),김용훈(Younghun Kim),박정배(Jeongbae Park) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11

This paper is about tire model blocked force simulation development and Structure-borne Noise (SBN) sensitivity research using results according to Tire Design Parameter (TDP). First, we generate a tire substructure model for blocked force simulation. For tire substructure model, it is generated using the commercial program ABAQUS, and the model is generated by applying the Craig-Bampton Type condition for simulation. After that, a dynamic analysis of the model through MSC NASTRAN is conducted and Force, Moment, and Stiffness, which are functional tire characteristics (FTC) values in the tire shaft center, are derived. Each result value is combined with a vehicle model through FRF-based Substructuring (FBS) theory and used for indoor vehicle SBN prediction. Second, we select 26 TDPs through blocked force simulation process. Each parameters are divided into upper and lower values and finally we generate 53 tire models. Using the derived results in the tire shaft center, parameters related to SBN based on tire model are determined and sensitivity analysis is conducted.

A study for production simulation model generation system based on data model at a shipyard

Back, Myung-Gi,Lee, Dong-Kun,Shin, Jong-Gye,Woo, Jong-Hoon The Society of Naval Architects of Korea 2016 International Journal of Naval Architecture and Oc Vol.8 No.5

Simulation technology is a type of shipbuilding product lifecycle management solution used to support production planning or decision-making. Normally, most shipbuilding processes are consisted of job shop production, and the modeling and simulation require professional skills and experience on shipbuilding. For these reasons, many shipbuilding companies have difficulties adapting simulation systems, regardless of the necessity for the technology. In this paper, the data model for shipyard production simulation model generation was defined by analyzing the iterative simulation modeling procedure. The shipyard production simulation data model defined in this study contains the information necessary for the conventional simulation modeling procedure and can serve as a basis for simulation model generation. The efficacy of the developed system was validated by applying it to the simulation model generation of the panel block production line. By implementing the initial simulation model generation process, which was performed in the past with a simulation modeler, the proposed system substantially reduced the modeling time. In addition, by reducing the difficulties posed by different modeler-dependent generation methods, the proposed system makes the standardization of the simulation model quality possible.

A study for production simulation model generation system based on data model at a shipyard

백명기,이동건,신종계,우종훈 대한조선학회 2016 International Journal of Naval Architecture and Oc Vol.8 No.5

Simulation technology is a type of shipbuilding product lifecycle management solution used to support production planning or decisionmaking. Normally, most shipbuilding processes are consisted of job shop production, and the modeling and simulation require professional skills and experience on shipbuilding. For these reasons, many shipbuilding companies have difficulties adapting simulation systems, regardless of the necessity for the technology. In this paper, the data model for shipyard production simulation model generation was defined by analyzing the iterative simulation modeling procedure. The shipyard production simulation data model defined in this study contains the information necessary for the conventional simulation modeling procedure and can serve as a basis for simulation model generation. The efficacy of the developed system was validated by applying it to the simulation model generation of the panel block production line. By implementing the initial simulation model generation process, which was performed in the past with a simulation modeler, the proposed system substantially reduced the modeling time. In addition, by reducing the difficulties posed by different modeler-dependent generation methods, the proposed system makes the standardization of the simulation model quality possible.

극한치이론을 이용한 VAR 추정치의 유용성과 한계:우리나라주식시장을중심으로

김규형,이준행 한국재무관리학회 2005 財務管理硏究 Vol.22 No.1

This study applies extreme value theory to get extreme value-VAR for Korean Stock market and showed the usefulness of the approach. Block maxima model and POT model were used as extreme value models and tested which model was more appropriate through back testing. It was shown that the block maxima model was unstable as the variation of the estimate was very large depending on the confidence level and the magnitude of the estimates depended largely on the block size. This shows that block maxima model was not appropriate for Korean Stock market. On the other hand POT model was relatively stable even though extreme value VAR depended on the selection of the critical value. Back test also showed VAR showed a better result than delta VAR above 97.5% confidence level. POT model performs better the higher the confidence level, which suggests that POT model is useful as a risk management tool especially for VAR estimates with a confidence level higher than 99%. This study picks up the right tail and left tail of the return distribution and estimates the EVT-VAR for each, which reflects the asymmetry of the return distribution of the Korean Stock market. 본 연구는 극한치 이론을 적용하여 국내 주식시장에 대한 VAR값을 구하고 이의 유용성을 살펴보았다. 극한치모형으로는 블록최대값모형과 POT 모형을 이용하였고 백테스트를 통하여 이들 모형의 적정성을 알아보았다. 극한치모형 중 블록최대값 모형은 신뢰수준의 변화에 따라 VAR 추정치의 변동이 매우 큰 것으로 나타났으며, 블록의 크기를 어떻게 선택하는가에 따라 모수의 추정치가 크게 달라져 VAR값의 안정성이 떨어지는 것으로 나타났다. 이는 국내 주식시장에 대해 VAR 측정시 블록최대값 모형을 사용하는 것은 적절치 않음을 시사하는 것이다. 반면 POT모형은 임계치의 선택에 따라서 VAR 값이 달라지기는 하나 상대적으로 안정적인 모습을 보이며, 또한 백테스트 결과 97.5% 이상의 신뢰수준에서 VAR값이 델타 VAR에 비하여 우수한 성과를 보이는 것으로 나타났다. 특히 POT모형은 신뢰수준이 높아질수록 그 우월성이 높은 것으로 나타나, 주로 99% 이상의 높은 신뢰수준의 VAR값을 이용하는 경우에 위험의 관리수단으로 유용한 모형임을 시사하고 있다. 또한 극한치모형은 수익률의 왼쪽 꼬리와 오른쪽 꼬리를 분리하여 추정하고 이를 VAR의 계산에 이용하기 때문에, 수익률분포가 비대칭적 특징을 보이는 우리나라 주식시장의 VAR 측정시 적절한 방법임을 확인할 수 있었다..

절리 영속성이 사각 단면 지하공동에서의 사면체 블록 형성에 끼치는 영향

조태진(Taechin Cho) 한국암반공학회 2016 터널과지하공간 Vol.26 No.6

지하공동 굴착현장에서 관찰되는 절리분포 양상에 대한 자료를 기반으로 굴착과정에서 형성될 수 있는 사면체 블록의 형상, 규모 및 붕락 가능성을 절리 영속성을 고려하여 예측하는 수치해석 기법을 개발하였다. 절리 영속성 분석결과를 이용하여 절리면의 확장성에 따른 개착면에서의 표출정도 및 블록형성 가능성 해석을 수행하는 기능을 고안하여 기존에 개발된 결정론적 3차원 블록해석모델에 접목시켰다. 개선된 수치해석모델의 신뢰성을 고찰하기 위하여 실제 블록 붕락이 발생된 굴착현장에 대한 해석을 수행하였다. 조사된 절리분포 양상에 의거하여 대표 방향성을 설정하고 잠재적 블록 형성을 분석하여 붕락된 블록 형상에 부합된 해석 결과를 도출하였으며, 이에 근거하여 굴착과정에서의 붕락 진행 미캐니즘을 블록형상을 고려하여 고찰하였다. A numerical analysis model capable of predicting the shape, the size and the potentiality of collapse of tetrahedral blocks considering the persistence obtained from the field survey of joint distribution around the underground excavation surface has been developed. Numerical functions of analyzing both the exposed trace distribution on the excavation surface and the formation of tetrahedral block controlled by the extent of joint surface have been established and linked to the previously developed three dimensional deterministic block analysis model. To illustrate the reliability of advanced numerical model the case of underground excavation in which the collapse of rock block had practically taken place was studied. Representative orientations of joint sets was determined based on the joint distribution pattern observed on the excavation surfaces. The formation of block on the roof of underground opening was analyzed to unveil the potential tetrahedral block the shape of which was very similar to the collapsed rock block. Mechanisms of collapse process has been also analyzed by considering the three dimensional shape of tetrahedral block.

유한 상태 기계와 병행 흐름도 방식을 활용한 그래픽 기반 로봇 시나리오 스크립트 모델

박홍성,김미숙,이경숙 제어·로봇·시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.3

In general, it is possible to program a robot application scenario more easily if the creation of the scenario is divided into the following two steps: (1) create the unit behaviors performed by the robot, and (2) decide the order of the unit behaviors developed in the previous step. This paper proposes a scenario development model consisting of these two steps, where a finite-state machine (FSM) script model and a block function script model are used to create unit behaviors and a concurrent execution flow script model is used to decide the order of the unit behaviors. The proposed models use a graphics-based authoring method. The FSM script model and the block function script model create their unit behaviors in the scenario by reusing various developed software modules. The concurrent execution flow script model creates an operation sequence of unit behaviors that is suitable for the application scenario using the FSM and block function script models. The software modules linked to the FSM and the block function script models are OPRoS, ROS, C/C ++, Java, and Python. The concurrent execution flow script model is stored and used in XML format for portability. Finally, an example is implemented to validate the proposed model.

Development of effective thermal conductivity models for Reserve Shutdown Control fuel block of prismatic HTGR for hydrogen production

Shin, Dong-Ho,Yoon, Su-Jong,Cho, Hyoung Kyu,Park, Goon-Cherl,Kim, Taewan Pergamon Press 2017 International journal of hydrogen energy Vol.42 No.29

<P><B>Abstract</B></P> <P>A hydrogen production system coupled to High Temperature Gas-cooled nuclear Reactor (HTGR) is considered to be one of the most promising ways for massive hydrogen production. For the reliability of the coupled system, the safety analysis on the HTGR is to be conducted by a system-scale analysis code. The system-scale analysis code adopts an effective thermal conductivity (ETC) model for a fuel block due to its complex geometry containing large number of coolant holes and nuclear fuel rods. The ETC of the fuel block is crucial to calculate the heat transfer inside the reactor core and prediction of thermal distribution over the reactor core is the most significant for the safety analysis of HTGR. Therefore, the verification of the ETC model that contributes to the prediction is essential. This ETC model based on Maxwell's theory shows an inaccurate prediction when the configuration of the composite materials is not homogeneous. Since the geometry of Reserve Shutdown Control (RSC) fuel block of HTGR is not homogeneous due to a large RSC hole, the ETC model for RSC fuel block should be developed to improve the accuracy and reliability of the reactor system analysis code. In this study, the two ETC models for the RSC fuel block have been developed by the thermal network modeling. Computational fluid dynamic simulations with a real geometry were performed to evaluate the accuracy of the ETC models for the RSC fuel block. The comparative result between CFD analysis and the ETC model shows that the newly developed model predicts the effective thermal conductivity of RSC fuel block more accurately than the previous model.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Study on the analyzing method on thermal distribution of High Temperature Gas-cooled nuclear Reactor (HTGR) is presented. </LI> <LI> Effective thermal conductivity model for Reserved Shutdown Control (RSC) fuel block was developed. </LI> <LI> The developed ETC model was evaluated over wide range of temperature and neutron fluence by CFD analysis. </LI> </UL> </P>

Power Distribution Network Modeling using Block-based Approach

Chew, Li Wern The Korean Microelectronics and Packaging Society 2013 마이크로전자 및 패키징학회지 Vol.20 No.4

A power distribution network (PDN) is a network that provides connection between the voltage source supply and the power/ground terminals of a microprocessor chip. It consists of a voltage regulator module, a printed circuit board, a package substrate, a microprocessor chip as well as decoupling capacitors. For power integrity analysis, the board and package layouts have to be transformed into an electrical network of resistor, inductor and capacitor components which may be expressed using the S-parameters models. This modeling process generally takes from several hours up to a few days for a complete board or package layout. When the board and package layouts change, they need to be re-extracted and the S-parameters models also need to be re-generated for power integrity assessment. This not only consumes a lot of resources such as time and manpower, the task of PDN modeling is also tedious and mundane. In this paper, a block-based PDN modeling is proposed. Here, the board or package layout is partitioned into sub-blocks and each of them is modeled independently. In the event of a change in power rails routing, only the affected sub-blocks will be reextracted and re-modeled. Simulation results show that the proposed block-based PDN modeling not only can save at least 75% of processing time but it can, at the same time, keep the modeling accuracy on par with the traditional PDN modeling methodology.

수치해석을 이용한 말뚝이 결합된 블록식방파제의 수평저항력에 관한 연구

이원효,권순구,김태형 한국해안,해양공학회 2022 한국해안해양공학회 논문집 Vol.34 No.4

Three-dimensional FEM numerical analysis was performed to understand the behaviors of blocks and piles according to the horizontal load for the block breakwater combined with piles. The Modified Mohr-Coulomb model, the improved version of the Mohr-Coulomb model, was applied for the ground modeling. The cases when the pile is embedded only into the block, embedded to the riprap layer (H = 4.29 cm), and embedded to the ground down to 2H, 3H, and 4H were examined. The results of the laboratory model experiment and the numerical analysis showed similar horizontal resistance force-displacement behaviors. The pile showed rotational behavior up to the embedment depth of 1H~2H and bending behavior in the case of 3H~4H depth embedment. When the embedment depth of the pile is 3H or more, the pile shows a bending behavior, so it can be considered that the pile contributes significantly to the horizontal resistance of the block breakwater. The results of this study will be used for various numerical analyses for real-size structure design. 본 연구는 말뚝이 결합된 블록식방파제에 대하여 수평하중 재하에 따른 블록과 말뚝의 거동을 파악하기 위하여 FEM 3차원 수치해석을 실시하였다. 지반구성모델은 Mohr-Coulomb 모델을 향상시킨 Modified Mohr Coulomb 모델을 적용하였다. 말뚝이 블록에만 관입된 경우, 사석층(H = 4.29 cm)까지 근입된 경우, 원지반속에 근입된 2H, 3H, 4H의 경우에 검토하였다. 실내모형실험 결과와 수치해석를 비교한 결과, 수평저항력-변위가 서로 유사한 거동을보이는 것으로 나타났다. 말뚝의 근입깊이가 1 H~ 2H까지는 말뚝이 회전거동을 보이고, 3H~4H의 경우에는 휨거동양상을 보이는 것으로 해석되었다. 말뚝의 근입깊이가 3H 이상인 경우에는 말뚝이 휨거동을 보이므로 말뚝이 블록식방파제의 수평저항력에 크게 기여한다고 볼 수 있다. 본 연구 결과는 실제 크기 구조물 설계를 위한 다양한 수치해석 시 자료로 활용이 있을 것이다.

Perfectly-Matched DC Blocks Terminated in Arbitrary Impedances

안희란,김범만,Ahn, Hee-Ran,Kim, Bum-Man The Korean Institute of Electromagnetic Engineerin 2007 한국전자파학회논문지 Vol.18 No.8

임의의 종단 임피던스를 갖는 DC block을 정합하기 위한 새로운 설계식이 소개되었으며, 이 설계식을 이용한 microstrip DC block이 제작, 측정되었다. 기존의 DC block은 완전히 정합기지 않았기 때문에, 한 단자에서 여기 된 power가 다른 단자로 모두 전달되지 않는 문제점이 있었다, 이런 문제점을 해결하기 위하여, 한 단자의 등가 공진기 회로를 제시하였으며, 이 등가회로를 이용하여, coupling coefficient에 관계없이, 어느 경우에도 완전 정합을 이룰 수 있는 설계식을 유도했다. 이 설계식을 이용하여 측정된 microstrip DC block의 삽입, 반사 손실은 중심 주파수 4.1 GHz에서 0.82dB, -31dB를 보였으며, 이 측정 결과는 예상된 결과와 잘 일치함을 보여주고 있다. Design equations of DC blocks terminated in arbitrary impedances are newly suggested and a microstrip DC block is tested for the perfect matching. The DC block is a two-port passive component and the power excited at a port is transmitted into another port. However, all the excited power at the input can not be delivered to the output and therefore most of the conventional DC blocks can not be perfectly matched with arbitrary termination impedances. To solve the matching problem, its one-port equivalent resonant circuit model, front which design equations can be derived, is newly suggested. Using the derived design equations, any DC block can be designed, perfectly matched without any restriction of coupling coefficients. To verify the derived design equations, measurements were carried out and the results are in good agreement with prediction, showing insertion and return losses at 4.1 GHz are 0.82dB and -31dB, respectively.