• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.50-53
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• 2003

Most companies use technologies such as stereolithography, selective laser sintering, and fused deposition modeling to make parts for such small consumer products as telephones, heads, and shoes. The largest part that the existing RP systems can make is only 600 mm in length. Because most RP systems build parts by depositing, solidifying, or sintering material point-by-point, making larger objects takes a long time. and in many cases, large objects won't fit the build size. A new effective thick-layered RP process. Transfer type Variable Lamination Manufacturing using expandable polystyrene foam (VLM-ST) has been developed with thick layers and sloped surfaces. In this paper, a scaledown model of F16 Fighter with the length of 800 mm is rapidly fabricated using the VLM-ST process. In order to build a CAD model of F16 larger than 600 mm in length, the approach in VLM-ST is to build larger parts in multiple sub-parts and then glue them together. The fabricated result shows that the VLM-ST process employing thick layers and sloped surfaces is adequate for creating the real-sized large objects in the diverse fields such as automobiles, electric home appliances, electronics. and etc.

• Steel and Composite Structures
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• 제26권3호
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• pp.289-301
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• 2018

The rigid steel connections were suffered severe damage because of low rotational capacity during earthquakes. Hence, many investigations have been conducted on the connections of steel structures. As a solution, steel slit dampers were employed at the connections to prevent brittle failure of connections and damage of main structural members. Slit damper is a plate or a standard section with a number of slits in the web. The objective of this paper is to improve the seismic performance of steel slit dampers in the beam-to-column connection using finite element modeling. With reviewing the previous investigations, it is observed that slit dampers were commonly fractured in the end parts of the struts. This may be due to the low participation of struts middle parts in the energy dissipation. Thus, in the present study slit damper with elliptic slits is proposed in such a way that end parts of struts have more energy absorption area than struts middle parts. A parametric study is conducted to investigate the effects of geometric parameters of elliptic slit damper such as strut width, strut height and plate thickness on the seismic performance of the beam-to-column connection. The stress distribution is improved along the struts in the proposed slit damper with elliptic slits and the stress concentration is decreased in the end parts of struts. The average contributions of elliptic slit dampers, beam and other sections to the energy dissipation are about 97.19%, 2.12% and 0.69%, respectively.

• 대한기계학회논문집 C: 기술과 교육
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• 제3권2호
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• pp.155-164
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• 2015

기존의 자동차 생산라인의 경우 샤시를 중심으로 양측에 일렬로 배치된 로봇들이 작업을 진행하기 때문에 길고 넓은 공장 부지가 필요하다. 하지만 일렬이 아닌 이열 삼열로 로봇을 배치하여 작업을 진행할 수 있다면, 생산 공장 부지를 최대 절반이하로 줄일 수 있고, 생산 설비를 보다 적은 면적에 설치함으로 로봇 구동 에너지 또한 감소시킬 수 있다. 하지만, 이와 같이 좁은 공간에서 다양한 작업을 수행하려면 여러 작업 기구 장착이 가능한 모듈형 로봇과 원거리에서도 작업이 가능한 가늘고 긴 형태의 로봇 매니퓰레이터를 개발해야만 한다. 이때 로봇을 가상의 공간에서 사전에 모델링해서 가장 최적의 로봇 형태에 대한 성능 평가를 진행할 수 있다면 로봇 개발시 개발 시간의 단축과 개발 비용을 획기적으로 줄일 수 있는데 이러한 평가 작업에 CAE기법들이 활용된다. 특히 로봇의 동역학적 거동 특성을 분석하기 위해서는 다물체 동역학 기법이 활용되는데, 이때 기존 모델링 기술보다 더 효과적이고 좋은 결과를 얻을 수 있는 효율적인 로봇 동해석 모델링 기술에 대하여 연구 진행되었다.

• 디지털콘텐츠학회 논문지
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• 제18권4호
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• pp.723-731
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• 2017

고고자료의 복원은 과거 기록물로 남겨진 사진과 도면자료를 이용하여 진행하였다. 크게 유구와 유물로 구분하여 살펴보았다. 유구에 대한 복원은 사진으로 남겨진 개개 부위 및 부분을 모델링하고, 이들을 정렬 및 합성하여 하나의 객체로 3차원 복원하였다. 유물에 대한 복원은 사진을 통한 모델링 작업을 우선한 후, 모델링된 유물의 파손 부위에 대한 텍스쳐 이미지를 수정하여 원상 복원하거나, 유물 내 결실부위에 대한 모델링 제작과 합성을 통한 원상을 복원하는 방식이 있다. 도면을 통한 복원은 3차원 모델링 제작과 함께 이미지의 실사맵핑을 통한 복원을 진행하였다. 이렇게 복원된 고고자료는 과거 2D자료를 통한 수치 분석과 해석의 연구성과를 검증하고 비교를 진행할 수 있으며, 추후 더욱 정확한 분석 방안을 제시할 수 있다.

• Structural Engineering and Mechanics
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• 제60권4호
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• pp.655-665
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• 2016

This paper aims to develop models to accurately predict the behavior of fresh concrete exposed to vibration using artificial neural networks (ANNs) model and regression model (RM). For this purpose, behavior of a full scale precast concrete mold was investigated experimentally and numerically. Experiment was performed under vibration with the use of a computer-based data acquisition system. Transducers were used to measure time-dependent lateral displacements at some points on mold while both mold is empty and full of fresh concrete. Modeling of empty and full mold was made using both ANNs and RM. For the modeling of ANNs: Experimental data were divided randomly into two parts. One of them was used for training of the ANNs and the remaining part was used for testing the ANNs. For the modeling of RM: Sinusoidal regression model equation was determined and the predicted data was compared with measured data. Finally, both models were compared with each other. The comparisons of both models show that the measured and testing results are compatible. Regression analysis is a traditional method that can be used for modeling with simple methods. However, this study also showed that ANN modeling can be used as an alternative method for behavior of fresh concrete exposed to vibration in precast concrete structures.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.893-898
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• 1994

In this paper, the influence of voice source estimation and modeling on speech synthesis and coding is examined and then their new estimation and modeling techniques are proposed and verified by computer simulation. It is known that the existing speech synthesizer produced the speech which is dull and inanimated. These problems are arised from the fact that existing estimation and modeling techniques can not give more accurate voice parameters. Therefore, in this paper we propose a new voice source estimation algorithm and modeling techniques which can not give more accurate voice parameters. Therefore, in this paper we propose a new voice source estimation algorithm and modeling techniques which can represent a variety of source characteristics. First, we divide speech samples in one pitch region into four parts having different characteristics. Second, the vocal-tract parameters and voice source waveforms are estimated in each regions differently using sequential SVD. Third, we propose composite source model as a new voice source model which is represented by weighted sum of pre-defined basis functions. And finally, the weights and time-shift parameters of the proposed composite source model are estimeted uning EM(estimate maximize) algorithm. Experimental results indicate that the proposed estimation and modeling methods can estimate more accurate voice source waveforms and represent various source characteristics.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.13-16
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• 2002

In this research, the design methods of the rocket joint parts were suggested. In the first section, nonlinear finite element analyses for joint parts of a composite pressure tank were performed. In the analyses, the detailed finite element modeling was performed and complex boundary conditions(contact problem, clamping force) were considered. Secondly, several guidelines for the design of joint parts were suggested. The parametric study for geometric design variables was peformed. Finally, the parametric study result was categorized for the multi-Joint part design of the axi-symmetric composite structure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1765_1766
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• 2009

In this paper, we propose the mathematical model for the vehicle system and the observer for adhesion force. To model the dynamic properties of vehicle system, we have considered two fundamental parts. The first part is the motion equations for vehicle based on Newton's second law. The second part is the torque dynamics of the traction motor. These parts are affected by outer conditions such as adhesive coefficient, running resistance and gradient resistance. The each parts are presented by the numerical formula. From two equations, we get the observer on adhesion force. Simulation results show that the proposed observer have the good performance compared with the normal observer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.827-833
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• 2001

This study is an introduction of ADS in which we have written out programs which can design three-dimensional machine parts and reduce the required time for design them comparing with other CADs. Among the machine parts, screws are commonly used in joining one part to another because of easy handing but welding and rivet are used to join permanently them even thought hard operation. Consequently, we have developed the screw for permanent fixing using stairs type screw threads, which is considered as the main machine parts in joining. For that, we designed permanent fastened screws according to the different rotation angle using VisualLISP and transferred it to ANSYS, structural solution program, to find out allowance load, maximum equivalent stress and where it occur.

• 전기학회논문지
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• 제56권11호
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• pp.1955-1961
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• 2007

In this paper, we propose the mathematical model for the vehicle system including running characteristics. The well defined model for a system is necessary to study and to enhance system performance. To model the dynamic properties of vehicle system, we have considered two fundamental parts. The first part is the motion equations for vehicle based on Newton's second law. The second part is the torque dynamics of the traction motor. These parts are affected by outer conditions such as adhesive coefficient, running resistance and gradient resistance. The each parts are presented by the numerical formula. To test the driving characteristics of the developed model, we performed the simulations by dynamic system simulation software, "SIMULINK" and the results are given for several conditions.