• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.4
• /
• pp.362-369
• /
• 2011

In this paper, vSLAM aided integrated navigation system is implemented and performance analysis of the system is completed via flight test. The system can suppress divergence of position error of INS only system by updating vSLAM correction information when temporary GPS signal outage occurs in bad radio condition. In the flight test, integrated hardware containing GPS, IMU and camera is loaded under RC electric helicopter. Performance of the integrated navigation system is verified by comparing estimated position of INS/vSLAM system with that of INS only system.

• Journal of Korea Foundry Society
• /
• v.28 no.2
• /
• pp.74-78
• /
• 2008

An integrated riser heating equipment has been developed to control shrinkage defects originated from casting of a marine propeller. The integrated riser heating equipment is composed of up/down moving parts, heating power source parts and an integrated controller. Heat capacity putting into the riser was calculated quantitatively on the base of a heat transfer analysis, which consisted of the establishment of heating model and the theoretical analysis for heat transfer. The riser heating equipment was evaluated through arc heating and electro-slag heating method. With the results, the arc type heating method was selected by considering high thermal efficiency, inexpensive cost, and convenient workship. This equipment improves the quality of a propeller casting and the poor working environment.

• Aerospace Engineering and Technology
• /
• v.10 no.1
• /
• pp.30-38
• /
• 2011

Structural effects of several geometric parameters such as shroud thickness, edge roundness and fillet radius of turbopump turbine blade were investigated throughout transient finite element analyses. Usually shroud is inserted to increase aerodynamic efficiency, but blocks deformation of blades. Therefore it can increase stress level in a structural point of view. Likewise, edge roundness and fillet between blades are also parameters where aerodynamics and structural mechanics should compromise. In this study, overall stress levels according to the geometric parameters were thoroughly investigated and the results could be utilized to determine optimal geometries.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.7 no.1 s.24
• /
• pp.57-66
• /
• 2007

The purpose of this study is both the variation of hydrologic topographical informations extracted by using WMS and the quantitative effect of rainfalll-runoff simulation due to dividing watershed. Miho stream basin in Geum river was selected by this study. Watershed dividing method are determined by area, channel slope and channel length. Hydrological response of divided watershed using Clark method, SCS method and Snyder method was compared with actual measured flood hydrograph. As a results, area-based watershed dividing method are particularly suitable the hydrologic applications using SCS method. This study can be used as basic data for the phase of the runoff variation in Miho stream basin.

• Aerospace Engineering and Technology
• /
• v.5 no.2
• /
• pp.174-180
• /
• 2006

The present paper describes transient thermal and mechanical analyses of a lox/kerosene type turbopump in a LRE(Liquid Rocket Engine). Turbopumps are used to pressurize propellants to achieve higher specific impulse of LRE. The turbopump under development has been designed and verified by structural analyses using finite element methods. Some parts of the turbopump operate under cryogenic environments, while the others work under ambient and high temperature environments. Therefore, numerical analysis at a turbopump system level is essential. In this study, casing assemblies of lox pump and fuel pump were analyzed to determine strength test and air-tightness test conditions. Also, some operational stress and strains of fuel pump casings were measured and analyzed. Based on these results, stress concentration of fuel pump casings during the operation could be successfully predicted.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.1
• /
• pp.88-98
• /
• 2000

Cooperative query answering provides neighborhood or associate information relevant to the initial query using the knowledge about the query and data. In this paper, we present an intelligent query answering system for suporting cooperative query answering system presented in this paper performs query relaxation process using hybrid knowledge base. The hybrid knowledge base which is used for relaxation of queries, composes of semantic list and rule based knowledge base for structural approach. Futhermore, this paper proposes the query relaxation algorithm for query reformulation using initial query on the basis of hybrid knowledge base.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.17 no.6
• /
• pp.105-112
• /
• 2013

Turbopump is typically an assembly of rotors and casings, and there are a number of joints between them. Every joint should be leak-proof, so there is always a seal to accomplish the goal. Among various seals, metal seals are advantageous in that they are robust at high pressure, and at wide range of temperature. In this study, flange joints using conical seal made of stainless steel, solid flat metal seal made of copper and metal C seal made of Inconel 718 were structurally designed and analyzed, considering both initial tightening and operating conditions.

• The KSFM Journal of Fluid Machinery
• /
• v.7 no.5 s.26
• /
• pp.20-28
• /
• 2004

Static and dynamic structural analyses of a turbine bladed-disk for a liquid rocket turbopump are performed to investigate the safety level of strength and vibration at design point. During operation, turbopump is exposed to various external loads. Therefore, the effects of them should be carefully considered and properly modeled. First, due to the high rotational speed of the turbopump, effects of centrifugal forces are considered in the structural analysis. Thermal load caused by severe temperature differences is also considered. A three dimensional finite element method (FEM) is used for linear and nonlinear structural analyses with modified Newton-Raphson iteration method. After the nonlinear solution is obtained from the structural analysis, dynamic characteristics are obtained as a function of rotational speed from the linearized eigenvalue analysis at an equilibrium position. From the analysis results, characteristics of stress distribution and vibration were thoroughly examined and investigated.

• Journal of Korean Society for Quality Management
• /
• v.26 no.1
• /
• pp.192-200
• /
• 1998

The quickest path problem is one of the important things for quality of services in communication networks. It is to find a path to send a given amount of data from the source to the sink with minimum transmission time, where the transmission time is dependent on both the capacities and the traversal times of the arcs in the network. This is found under the networks that the capacity and the lead time of each ring are predetermined. It is general to solve the quickest path problem using shortest path algorithms. The relevant algorithms proposed till now are based on the capacity of rings in distributed environments. When the configuration of networks is changed, there can be two a, pp.oaches to find the quickest paths. The one is to find new quickest paths, and the other is to update the current quickest paths. As one of the algorithms for the latter, the distributed quickest path update algorithm was proposed. This paper aims to propose the distributed algorithm a, pp.icable to find the quickest path, when the configuration of networks is changed, using the quickest path tree update altorithm, and to verify its possibility of a, pp.ication by analyzing the transmission amount of data from one node to another from the theoretical point of view.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.117-122
• /
• 2012

A blisk with rotor shroud is usually adopted in LRE turbine to maximize its performance. However it experiences severe thermal load and resulting damage during engine stating and stop. Shroud splitting is devised to relieve thermal stress on the turbine rotor. Structural analysis confirmed the reduction of plastic strain at the blade hub and tip. However, split gap at the rotor shroud entails additional tip leakage and results performance degradation. In order to assess the effect of shroud split on the turbine performance, tests have been performed for various settings of shroud split. For the maximum number of shroud splitting, measured efficiency reduction ratio was 2.65% to the value of original shape rotor.