Comparison of Brazed Residual Stress and Thermal Deformation between X-Type and Pyramidal Lattice Truss Sandwich Structure: Neutron Diffraction Measurement and Simulation Study

Jiang, Wenchun,Wei, Zhiquan,Luo, Yun,Zhang, Weiya,Woo, Wanchuck De Gruyter 2016 High temperature materials and processes Vol.35 No.6

<P><B>Abstract</B></P><P>This paper uses finite element method and neutron diffraction measurement to study the residual stress in lattice truss sandwich structure. A comparison of residual stress and thermal deformation between X-type and pyramidal lattice truss sandwich structure has been carried out. The residual stresses are concentrated in the middle joint and then decreases gradually to both the ends. The residual stresses in the X-type lattice truss sandwich structure are smaller than those in pyramidal structure. The maximum longitudinal and transverse stresses of pyramidal structure are 220 and 202 MPa, respectively, but they decrease to 190 and 145 MPa for X-type lattice truss sandwich structure, respectively. The thermal deformation for lattice truss sandwich panel structure is of wave shape. The X-type has a better resistance to thermal deformation than pyramidal lattice truss sandwich structure. The maximum wave deformation of pyramidal structure (0.02 mm) is about twice as that of X-type (0.01 mm) at the same brazing condition.</P>

레벨 정보를 이용한 효과적인 구조 조인 기법

김종익(Jongik Kim) 한국정보과학회 2008 정보과학회 컴퓨팅의 실제 논문지 Vol.14 No.6

구조 조인은 XML 경로 질의를 처리하기 위한 대표적인 방법 중의 하나이다. 최근의 연구에서는 B+트리 등에 색인된 가로 방향의 엘리먼트 분포 정보를 이용하여 조인 결과에 포함되지 않는 엘리먼트들을 조인 연산에서 배제하는 방법에 초점을 맞추고 있다. 하지만, 이러한 방법은 조인 연산 자체가 매우 복잡해지며 분포 정보를 위한 색인의 부담으로 항상 좋은 성능을 보장하지는 못한다. 본 논문에서는 레벨 정보를 이용하여 조인 결과에 참여하지 못하는 엘리먼트들을 효과적으로 걸러내는 구조 조인 기법을 제안한다. 제안하는 기법의 레벨 정보는 엘리먼트의 세로방향의 분포정보라는 점에서 기존의 기법과 차별화되며 조인 연산을 위한 별도의 색인을 필요로 하지 않는다는 장점을 가진다. 본 논문에서는 실험을 통하여 제안된 기법의 효율성을 보인다. Structural join is one of the most typical techniques for evaluating XML path queries. Recent researches for structural joins focus on techniques of skipping unnecessary elements using the horizontal distribution information of elements that is indexed on a structure like B+ tree. However, those techniques make the structural join complicated and cannot guarantee efficient join processing due to the overhead of an index structure. In this paper, we propose a new structural join technique that exploits the level information of XML elements. Our technique can skip unnecessary elements using level information, which is vertical distribution information of elements. Through the experimental results, we show that our technique can evaluate structural joins efficiently.

피라미드형 내부구조체를 가진 ISB 판넬의 접합형태에 따른 충격 특성 변화

안동규(Dong-Gyu Ahn),문경제(Gyung-Jae Moon),정창균(Chang-Gyun Jung),양동열(Dong-Yol Yang) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.9

ISB(Inner structured and bonded) panel with a pyramidal inner structure is actively developing to reduce the weight and to improve the crashworthiness of the material. The objective of this paper is to investigate into the variation of impact characteristics of ISB panels with a pyramidal inner structure according to joining types between skin sheets and inner structures. Several drop impact tests have been performed. In order to examine the impact characteristics at a drawing condition, drawing type of experimental set-up has been proposed. From the results of the experiments, the influence of joining types between skin sheets and the inner structures on the characteristics of the deformation, the energy absorption and the failure has been quantitatively examined. In addition, it has been shown that maximum load decreased and the maximum displacement increases as the joining type changes from the bonding to the welding. The results of the observation of the specimen have been shown that major wrinkles form in the minor crimping direction irrespective of the joining types. Through the comparison of the experimental results for bonding and welding specimens, it has been shown that the absorption energy of the bonded specimen is nearly 1.3-1.5 times of the welded specimen at the same displacement.

구조적 문서에서의 구조 조인 질의 처리

김병곤 부천대학 2003 論文集 Vol.24 No.-

최근 인터넷의 발전으로 인해 웹 상에서 두 개 이상의 데이터 소스들간의 데이터 교환과 전자 상거래 분야에서 데이터 또는 정보를 전자 문서로 만들고 효율적으로 관리하는 기법이 중요한 연구 주제로 인식되고 있다. 특히, 문서에 대한 통합 및 호환이 용이하고 문서의 재 사용성을 제공하는 XML과 같은 구조적 문서를 웹 상의 문서 표현 및 교환의 표준으로 인식됨에 따라 구조적 문서에 대한 검색 및 이에 관련된 연구들이 활발히 진행되고 있다 기존에 제안된 많은 질의어는 단일 문서상에서 내용 기반의 검색 또는 구조적 정보를 이용한 내용을 기반으로 한 내용 검색이 주를 이루고 있다. 본 논문에서는 다중 구조적 문서에서의 조인 질의 유형을 질의 특성에 따라 체계적으로 분류하였고, 순수 구조적 특징을 기반으로 조인이 가능하도록 순수 구조 기반의 조인 질의 유형을 제안하고 이에 따른 연산을 새롭게 정의하였다. 또한, 정보 검색 기능을 지원할 수 있는 유사성 조인 질의 연산을 정의하고, 제안된 새로운 질의 유형을 적응하기 위해 XML 표준 질의어인 XQuery 구문을 확장하였다. As the rapid development of internet, techniques of data exchanging among data sources on the web and managing information on electronic documents are regarded as important research areas. XML(eXtensible Markup Language) is considered as a standard format of data represent and exchange. Therefore, many works for retrieval of XML documents and its related techniques have been proposed. With these trends, W3C proposed XQuery as a standard XML query language after analyzing many XML query languages proposed formerly. However, most of proposed XML query languages are based on document content-based retrieval either using pure content or structural information in single document. In this paper, first, I systematically classified various join query types according to the query features. Second, I newly defined pure structure-based join query type and proposed the related operations. Third, I proposed similarity join query type to supporting information retrieval facility. Finally, to apply the newly proposed query types, I extended XQuery syntax which is a standard XML query language by W3C.

Joined-Wing UAV

Marshal Deep Kafle,Nikesh Bhattarai,Hyeon Beom Jo,Kyoung Mu Min,Han Yeong Baek,Byoung Soo Kim,Sung Hun Kim 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.4

Joined-wing UAV, known for its light weight, high stiffness and resistance to bending, better aerodynamic efficiency has been an air vehicle of interest for many researchers. In this paper, two types of configuration of Joined-Wing UAV are designed and the one better suiting the mission objective is further analyzed numerically. Its flight performance is further analyzed for varying weight and wingspan and the design fulfilling the mission requirements is examined. CFD analysis for the full scale model is also performed, followed by static structural analysis of composite structures. Its static and dynamic stability are also numerically studied. The analyses show satisfying results, based on which a halfscaled model is manufactured and flight test is performed to study and determine the control-law structure of the aircraft and to set the control-law design parameter for static performance. The results presented are a basis for the manufacture of full scale UAV.

IBAD 표면개질 기술을 이용한 브레이징 접합효과

전철호,옥철호 東亞大學交附設 生産技術硏究所 2005 生産技術硏究所硏究論文集 Vol.10 No.-

In this paper, brazing joining experiments for Al_(2)O_(3) - SUS304 were performed using the surface modification technique with IBAD(ion-beam assisted deposition)of active material and conventional Ag-Cu eutectic alloy filler metal. Al_(2)O_(3) ceramic surfaces were modified with ion beam bombardment prior to deposition and IBAD for reactive Ti coating to provide the required wetting capability of the filler metal on the ceramic surfaces and to reduce the thermal mismatch problem by forming the graded interlayer structure. The effects of reaction products on the rupture strength of the brazement on the process parameters such as brazing temperature, brazing time and the surface modification effects were tested based on the microstructure of the interlayer. The interfaces of these specimens were analyzed by the analytical devices such as atomic force microscope(AFM), energy dispersive analysis by X-Ray(EDAX), scanning electron microscope(SEM), X-Ray.

Aerodynamic Numerical Analysis of the Low Reynolds Number Diamond Joined-Wing Configuration Unmanned Aerial Vehicle

Junlei Sun,Heping Wang,Zhou Zhou,Shan Lei 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.3

Aerodynamic numerical simulation of low Reynolds number long-endurance Diamond Joined-Wing configuration unmanned aerial vehicle was performed. First, low Reynolds number aerodynamic characteristics of a typical wing are numerically simulated by solving the Reynolds averaged Navier–Stokes (RANS) equations based on the structural grid technology and the k–kL–ω transition model. To prove the accuracy of this method, experimental data and numerical simulation results were compared. Second, the performance of low Reynolds number Diamond Joined-Wing configuration UAV (unmanned aerial vehicle) aerodynamic characteristics and control surfaces was studied by numerical simulation and theoretical analysis. The analysis of the interference between the Frt-wing (front wing) and the Aft-wing (after wing) of the Diamond Joined-Wing configuration UAV and the reason for the change in the pitching moment in the lateral-directional motion is carried out. The results show that the Diamond Joined-Wing configuration UAV has a typical low Reynolds number surface flow characteristics, Frt-wing and Aft-wing flow interference are relatively minor at a small angle of attack, which has a high basic aerodynamic performance in addition to good stall characteristics, with longitudinal and lateral-directional static stability. The performance of control surfaces and flaps is higher to meet the design requirements. Finally, the accuracy of the numerical simulation results was verified by vehicle aerodynamic testing.

전통 목구조에 관한 구조 해석적 고찰

박세희(Park Se-Hee),정성진(Jung Sung-Jin),김호수(Kim Ho-Soo) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)

There are differences in joint style and member connection between Korean Traditional Wood Structrues and Western Wood Structures. These are peculiar and characteristic features of Korean Traditional Wood Structures, but make the analysis of structural stability difficult. The purpose of this study is to examine the structural meaning of the construction method and show logical models for the estimation of the structural stability on the Korean Traditional Wood Structures. For this purpose, one of the Korean Traditional Wood Structures-Mindori Style- was selected and its construction stage and load transfer mechanism was analyzed. It was also studied that how different behaviors the structural members show according to their joint style and load distribution. The results of this study were as follows; the step-by-step transfer of vertical load, multiplicity of joining method, these factors are important and remarkable in finding the reasonable analysis method of the Korean Traditional Wood Structures and some analytical models are presented by this study.

등가정하중을 이용한 접합날개의 구조최적설계

이현아(Hyun-Ah Lee),김용일(Yong-Il Kim),박경진(Gyung-Jin Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

The joined-wing is an airplane wing of a new concept. Its range and loiter are longer than those of a conventional wing. The joined-wing it can lead to increased aerodynamic performance, and structural weight saving. In this research, dynamic response optimization of a joined-wing is carried out by using the equivalent static loads. Equivalent static loads are made to generate the same displacement field as the one from dynamic loads at each time step of dynamic analysis. The gust loads are considered as critical loading conditions and they dynamically act on the structure of an aircraft. However, it is difficult to identify exact gust load profile. Therefore, approximated dynamic loads are generated. Static response optimization is performed for one case. One uses the same design variable definition as dynamic response optimization. The results are compared.

Alexandrov L-preuniform filter spaces

Ju-Mok Oh,Yong Chan Kim 원광대학교 기초자연과학연구소 2022 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.23 No.1

In this paper, we introduce the notion of Alexandrov L-(neighborhood) filters and Alexandrov L-preuniform filters as a topological viewpoint of fuzzy rough sets. We investigate the relations among Alexandrov L-neighborhood filters, L-fuzzy preorders and Alexandrov L-preuniform filter structures. Moreover, we investigate their topological properties and give their examples. As an application for a fuzzy information system, Alexandrov $L$-neighborhood filters, L-fuzzy preorders and Alexandrov L-preuniform filters are studied.