• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.78-83
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• 2012

Generally, the first stage of a launch vehicle requires high thrust to achieve a mission. We can use one high thrust level engine or a clustered engine system which made of several small thrust level engines to make high thrust. The first stage propulsion system of KSLV-II has 300tf thrust to satisfy the mission. But it is impractical to make high thrust by one engine at this moment in time. So we should cluster four 75tf class engines which can be applied to make a required thrust for the first stage propulsion system. This article deals with the concept of the first stage clustered engine arrangement of KSLV-II.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.626-631
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• 2012

In this study, fatigue life of the motor block bracket units for KTX-Sancheon trains was assessed. Design evaluation for railway structures was performed based on the UIC 566 regulation, and test and evaluation of fatigue life in welded parts was performed in accordance with standard ERRI B 12/RP17 and ERRI B 12/RP60. The actual vehicle dynamic stress testing was executed in KTX-Sancheon service line with the service operating speed. The dynamic stress was measured with commercial data acquisition system (MGC plus). The cumulative damage was evaluated by applying standard BS 7608 - Class F and cycle counting was used rain-flow counting method. As a result, the motor block bracket units for KTX-Sancheon trains was designed to fit the regulation and the safety of fatigue life for 30 years, assuming that KTX-Sancheon trains travels 600,000km annually, were confirmed under current operating conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.1
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• pp.88-95
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• 2015

This paper considers the effects of propellant mixture ratio and loading errors on the performance of a liquid rocket. Propellant residuals generated by error sources are analyzed for a launch vehicle model whose first stage consists of a cluster rocket of four 75-tonf class engines using a statistical Monte-Carlo approach and then the optimal fuel biases minimizing residuals are computed. The results are validated through comparison with analytic method using approximate formula, which have been applied for other space launch vehicles.

• International Journal of Fluid Machinery and Systems
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• v.8 no.1
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• pp.23-35
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• 2015

This paper presents the rotordynamic performance measurement of oil-free turbocharger (TC) supported on gas foil bearings (GFBs) for 2 liter class diesel vehicles and comparison to floating ring bearings (FRBs). Oil-free TC was designed and developed via the rotordynamic analyses using dynamic force coefficients from GFB analyses. The rotordynamics and performance of the oil-free TC was measured up to 85 krpm while being driven by a diesel vehicle engine, and compared to a commercial oil-lubricated TC supported on FRBs. The test results showed that the GFBs increased the rotor speed by ~ 20% at engine speeds of 1,500 rpm and 1,750 rpm, yielding the reduction of turbine input energy by more than 400 W. Incidentally, an external shock test on the oil-free TC casing was conducted at the rotor speed of 60 krpm, and showed a good capability of vibration damping due to the well-known dry friction mechanism of the GFBs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.193-196
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• 2007

The motor case for the KSLV-I KM is the first satellite launch vehicle ever to be developed by Korea to deliver the 100 kg class satellite into Earth's low orbit. This SLV is made of two stages, and the 2nd stage is made of solid rocket motor. The motor case of the KM is made of all composite materials except for the interface structures. Manufacturing process for the motor case such as insulation, filament winding for the motor case, fabrications for the interface structures will be discussed in this paper.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.548-551
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• 2010

A 150 lbf-thrust class micro turbojet engine has been developed. The engine could be applied to power plant for small aviation vehicle such as UAV, decoy and anti-radar missile and was designed with concepts that has small size, low-cost and high performance. A prototype was manufactured and performed the ground static test and high altitude test. This paper outlines the features and layout of 150 lbf turbojet engine and also describes the design characteristics and test results of the engine and components.

• 보존과학연구
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• s.20
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• pp.121-137
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• 1999

Among pigment used at work of Dan-Chung, Emerald Green is specific illuminating fluorescent light of green. It is very difficult to change other organic or inorganic pigment. All of the internal high class pigment has rare light. But Emerald Green is superior to fresh color and stability out of industrial chemical products. It forms over 50% of quantity and importance of a pattern painting. Emerald Green prohibited to produce because of its toxicpollutants, so required to changing pigment development. It is characterized to excellent color, convenient work, economical, against-sunlight, against-air pollutant and durability. The result of a test is follows; 1. We are investigated into producing internal natural Emerald Green, import external pigment and industrial synthesis method etc. but unable to buy because of its toxic pollutant. 2. We are made six samples by yellowish and green is hpigment mixing. We tested on against sunlight and air pollutant. The best mixing ratio is follows. Titanium Dioxide R760 : 18g- Chalk, White Wash : 10g- Permanent Yellow : 7g- Cyanine Green : 8g- Chrome Yellow : 3g- Resin(Vehicle) : Acryl Emulsion(Styrene + 2-Ethyl HexylAcrylate + Methyl Meth Acrylate) 8%

• IE interfaces
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• v.23 no.1
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• pp.48-57
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• 2010

A tryout is one of the most important process in development and production of dies. For automotive press dies, it takes 3 to 4 months during the vehicle development process. Moreover, useful information and knowledge from tryout process is very important to design and production planning of dies. In this paper, we developed a new supporting system for making and managing tryout reports of an automotive press die. The CBDTS(Case-Based reasoning for Die Tryout report System) was developed and applied using case-based reasoning method in order to reduce time and manage knowledge of tryout. It consists of "Class Retrieval Wizard", "Case Cleansing Module", and "Case Viewer." Also, this CBDTS could be a channel to integrate field information with enterprise-wide information management systems as well. The CBDTS was applied to a Korean automotive press die shop, and the results were very satisfied in both quantitative and qualitative manners.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.106-114
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• 2014

The interior permanent-magnet synchronous motor (IPMSM) is often used for the traction motor of hybrid electric vehicles (HEVs) and electric vehicles (EVs) due to its high power density and wide speed range. This paper introduces the 120kW class IPMSM for traction motors in military trucks. This system, as a SHEV (series hybrid electric vehicle), requires a traction motor that can generate high torque. This study introduces a way to reduce costs by proposing a design approach that creates reluctance torque that can be maximized by varying the dq-axis inductance. If a model designed by a design approach meets the desired torque, the magnetic torque can be reduced by an amount equal to the increase in reluctance torque and consequently the amount of permanent magnets can be reduced. A reduction gear and high speed operation of motors are necessary for the miniaturization of the motor. Thus, a fairly large centrifugal force is generated due to the high speed rotation. This force causes mechanical interference between the rotor and the stator, and a design approach for adding an iron bridge is explained to solve the interference. In this study, the initial model and the improved model that reduces cost and improves mechanical durability are compared by FEA, and the models are produced. Finally, the FEM results were verified experimentally.

• Journal of the Korean Institute of Navigation
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• v.20 no.2
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• pp.51-58
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• 1996

For the smooth flow of traffic vehicles and its effective management, it is necessary to have an exact information on traffic condition, i.e., the volume of traffic, velocity, occupancy and classification of vehicles. In particular, for classification of vehicles, there has been only image processing method using camera, where the method can obtain much information but rather expensive. In this paper, an algorithm for the measurement of velocity and total length of vehicles has been proposed to develop a general traffic management system, which is necessary to discriminate the class of vehicles. In order to realize the proposed algorithm, we have developed an ultrasonic spatial filtering method, which has better performance than that of using the traditional vehicle detector. To have this system to be constructed, we have introduced three sets of ultrasonic devices where each has one transmitter and two receivers which are arranged to obtain the spatial difference of objects. The velocity of vehicles can be measured by analyzing the occurrence time of pulses and their time differences. The total length of vehicles can be given by multiplying velocity with time interval of pulses sequence. To confirm the effectiveness of this measuring system, the experiment by the spatial filtering method using the ultrasonic sensors has been carried out. As the results, it is found that the proposed method can be used as one of measurement tools in the general traffic management system.