• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년 영문 학술대회
• /
• pp.503-505
• /
• 2008

The purpose of the current study is to examine the aerodynamic characteristics of two hypersonic vehicles in near space. One is derived from waverider shape, and the other from liftbody. The objective of this study are threefold. The first is to creat an computational database for hypersonic vehicle configurations. The second is to examine the effects of individual vehicle components on hypersonic configurations and to determine the differences in aerodynamic characteristics that result from integrating all vehicle components. The third objective is to evaluate the controllability of each of the fully integrated vehicles and the effectiveness of the control surface design. These objectives were accomplished using DSMC solutions and aerodynamic code developed in Northwestern Polytechnical University. The results are analyzed also in three sections. First, the results of the waverider shape and liftbody shape without integrated vehicle components are presented. Second, the results of adding aircraft components to the waverider shape and liftbody shape are presented. Finally, the aerodynamic characteristics of the fully integrated waverider-derived configuration and liftbody-derived configuration are examined and compared with those of the pure waverider shape and liftbody shape. Comparation between fully integrated waverider-derived configuration and liftbody-derived configuration are also presented in this paper.

• Advances in aircraft and spacecraft science
• /
• 제10권5호
• /
• pp.439-455
• /
• 2023

Free surface fluid oscillation in prolate spheroidal tanks has been investigated analytically in this study. This paper aims is to investigate the sloshing frequencies in spheroidal prolate tanks and compare them with conventional cylindrical and spherical containers to select the best tank geometry for use in space launch vehicles in which the volume of fuel is very high. Based on this, the analytical method (Fourier series expansion) and potential fluid theory in the spheroidal coordinate system are used to extract and analyze the governing differential equations of motion. Then, according to different aspect ratios and other parameters such as filling levels, the fluid sloshing frequencies in the spheroidal prolate tank are determined and evaluated based on various parameters. The natural frequencies obtained for a particular tank are compared with other literature and show a good agreement with these results. In addition, spheroidal prolate tank frequencies have been compared with sloshing frequencies in cylindrical and spherical containers in different modes. Results show that when the prolate spheroidal tank is nearly full and in the worst case when the tank is half full and the free fluid surface is the highest, the prolate spheroidal natural frequencies are higher than of spherical and cylindrical tanks. Therefore, the use of spheroidal tanks in heavy space launch vehicles, in addition to the optimal use of placement space, significantly reduces the destructive effects of sloshing.

• 한국항공우주학회지
• /
• 제48권7호
• /
• pp.537-546
• /
• 2020

우주발사체 개발과정에서 설계와 프로세스의 성능지표로 활용되는 신뢰도는 발사 성공률로 유효성이 확인되고, 반복된 발사를 통해 수집된 데이터는 신뢰도 관리를 위하여 피드백 되어야 한다. 본 논문에서는 전 세계 우주발사체의 발사 이력을 조사하여 발사체 모델이나 발사 운용을 통한 기술 성숙도에 따른 발사 성공률을 비교 분석하였고, 사전정보를 반영한 사전확률분포에 발사를 통해 관측된 데이터를 업데이트하는 베이지안 기법을 적용하여 다음 발사에서 예상되는 성공률을 추정하였다. 여러 유형의 사전확률분포를 사용하여 추정한 발사 성공률과 전통적인 통계 기법을 통해 산출한 성공률을 비교 분석하여 적절한 사전분포를 설정하는 방안을 검토하였고, 베이지안 기법을 적용하여 미래의 발사 성공률을 예측하기 위해 고려할 사항들을 제시하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.873_874
• /
• 2009

This paper presents a method for designing a high power motor that is applicable to electric vehicles. Interior Permanent Magnet (IPM) type motor which has high efficiency and high durability is selected. To apply for the electric vehicles, a form, a tire and a wheel of vehicles are considered when calculating a motor performance. After calculating a motor performance, space harmonic analysis and FEA(Finite Element Analysis) is used for designing In-Wheel motor.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 기술교육전문연구회
• /
• pp.90-95
• /
• 2003

For the safety driving of an automobile which is become individual requisites, a new Neural Network algorithm which recognized the load vehicles in real time is proposed. The proposed neural network technique is the real time computation method through the inter-node diffusion. In the network, a node corresponds to a state in the quantized input space. Each node is composed of a processing unit and fixed weights from its neighbor nodes as well as its input terminal. The most reliable algorithm derived for real time recognition of vehicles, is a dynamic programming based algorithm based on sequence matching techniques that would process the data as it arrives and could therefore provide continuously updated neighbor information estimates. Through several simulation experiments, real time reconstruction of the nonlinear image information is processed. 1-D LIPN hardware has been composed and various experiments with static and dynamic signals have been implemented.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.508-509
• /
• 2007

For the safty driving of an automobile which is become individual requisites, a new Neural Network algorithm which recognized the load vehicles in real time is proposed. The proposed neural network technique is the real time computation method through the inter-node diffusion. The most reliable algorithm derived for real time recognition of vehicles, is a dynamic programming based algorithm based on sequence matching techniques that would process the data as it arrives and could therefore provide continuously updated neighbor information estimates.

• 전력전자학회논문지
• /
• 제26권3호
• /
• pp.199-204
• /
• 2021

Ultra-compact electric vehicles have narrow space for power conversion devices. This work presents schemes to achieve the high-power density of a low-voltage DC-DC converter (LDC): simplifying a converter structure by using sync-buck topology, applying a planar inductor using PCB winding, and applying a plate-type heat sink. The heat sink is placed between two PCBs, which increases the contact surface between the PCB and the heat-dissipating device. It enables the miniaturization of the converter to improve the conditions of heat radiation. The validity of the proposed scheme is verified through the experiment using a 500 W(12 V, 41.67 A) prototype with an input voltage range from 58 V to 84 V.

• 국제학술발표논문집
• /
• The 6th International Conference on Construction Engineering and Project Management
• /
• pp.673-673
• /
• 2015

Earthwork is an operation that provides space for structures, and it takes up a large portion of the construction costs in a construction project. In large-scale earthwork, numerous types of construction equipment are used in the operation. The types of equipment should be selected based on the field conditions and the construction methods. These construction vehicles are constantly changing positions during the earthwork operation. Therefore, the equipment operators require effective communication to ensure the efficiency of the earthwork operation. All equipment operators should exchange information with the other equipment operators. Information should be exchanged continuously to support decision making and increase productivity during the earthwork operation at the construction site. This paper investigates the attributes required for an information interface between construction vehicles during an earthwork operation. This paper 1) discusses the importance of an information interface for construction vehicles in order to increase productivity during an earthwork operation, 2) analyses the types of attributes that need to be communicated between construction vehicles, and 3) provides a database that has been built for attribute control. The database built for the information interface between construction vehicles will enhance communication between vehicle operators. Table I shows the typical attributes that should be shared between the excavator operator and the dump truck operator. This information needs to be shared among the operators, as it helps them to plan the earthwork operation in a more efficient manner. A database has been developed to store this information in an entity relation diagram. A user-interface display environment is also developed to provide this information to the operators in the construction vehicles. The proposed interface can help exchange information effectively and facilitate a common understanding during the earthwork operation. For example, the vehicle operators will be aware of the planned volume, excavated volume, transportation time, and transportation numbers. As a part of this study, mobile devices, such as mobile phones and google glasses, will be used as hands-on communication tools.

• 항공우주시스템공학회지
• /
• 제10권1호
• /
• pp.74-81
• /
• 2016

Space propulsion system produces required thrust for satellites and space launch vehicles by using chemical reactions of a liquid fuel and a liquid oxidizer typically. Among several liquid propellants, the monomethylhydrazine-dinitrogen tetroxide is expecially preferred for a GEO satellite propellants due to their better storability in liquid phase during a long mission life under a freezing space environment. Recently, a development of the monomethylhydrazine-dinitrogen tetroxide bipropellant system becomes important as the national space program requires the heavier and the more efficient space system. Thus, the objective of the present study is to review a foreign research trend of a chemical reaction between the monomethyhydrazine fuel and the dinitrogen tetroxide oxidizer to understand a fundamental basis of their characteristics to prepare for domestic development in future.

• Structural Engineering and Mechanics
• /
• 제28권6호
• /
• pp.715-725
• /
• 2008

New types of armor, including space armor, multiple-layered armor, composite armor and modular armor have been successfully developed and installed on the armored vehicles of several nations. The protective capability of armor against penetration is established. Of developed composite armor, space armor has a simple structure and is easy to produce and can be produced at low cost. This study uses the finite element package DYTRAN and the pre and post processor PNTRAN to elucidate the ballistic resistance and penetration of space armor. Factors such as armor thickness, space between armors and projectile profile are considered. A technique for simulating the protection afforded by armor and supporting the design of space armor is developed.