• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.344-347
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• 2011

This paper presents qualification process of the T700/701K turbo-shaft engine for Korean Utility Helicopter(KUH). The T700/701K is the rear-drive variant of the GE's T700-701C/D engine which was qualified for military applications in the world. The main scope of the development is the modification from a front-drive engine to a rear-drive one, the performance enhancement of the power turbine and the incorporation of two channel FADEC(Full Authority Digital Engine Control) system for more reliable operation. Therefore, T700/701K engine must be qualified by Korean government in order to perform a flight in the country. Reflecting the influence of developing scope, the main requirements including performance and control are verified by test and analysis, while the requirement for module or component that is same to that of T700-701C/D are verified by similarity.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.601-610
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• 2018

This case study analyzed the effect of capstone design on students' competence and class satisfaction. Three subjects developed in S university were analyzed, and 92 students participated. Results show that the lesson structure of the capstone design was developed to provide students with problem solving competence and practical business skills through hands-on experience. In addition, the students' competence was enhanced, and their satisfaction in class was very high. Statistical results show that, compared to the existing classes, class satisfaction in capstone design improved significantly. Considering the foregoing results, this study suggested that for the capstone design, the lesson structure and method need to be diversified to provide more opportunities for students to participate and become active. The assessment procedure and method also have to be more objective to lessen subjectivity and to increase class satisfaction in capstone design.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.627-630
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• 2009

Ejector system can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an configuration and operating conditions for an ejector in the condition of sonic and subsonic. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Numerical simulation was adopted for an optimal geometry design and satisfying the required performance. Also, some ejectors with a various of nozzle throat and mixing chamber diameter were manufactured precisely and tested for the comparison with the calculation results.

• Journal of the Korean School Mathematics Society
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• v.20 no.2
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• pp.163-186
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• 2017

The purpose of this paper is to propose the policy change of teachers education in Korea with an analysis of America statistical literacy education. we found the difference of statistical literacy education between Korea and America with each nation's social and educational environment. We can get the need of new change for statistic teacher's education in Korea. We think of Mathematics teachers should know about the difference between statistics and mathematics at school mathematics. And they should know the new change thinking about teaching method and process assesment methods. Second, Teachers should focused on teaching of problem solving and statistical thinking ability based on data analysis than the teaching of probability and mathematical theory.

• Journal of Internet Computing and Services
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• v.21 no.2
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• pp.131-138
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• 2020

The SBA Integrated Information system is constructed and operated for scientific and systematic management of Defense information utilizing whole process of weapon system acquisition from requirement institution to operation maintenance. In order to utilize m&s resources actively and effectively in the life cycle of weapon system acquisition, efficient management plans of the SBA integrated Information system is required. As a result of identifying usage on SBA Information system and performance of operation performance measurement, it was defined that establishment of the SBA Integrated Information system process and provision of detailed system are mandatory for activating m&s resource and supporting process of acquisitions. In this study, Defense m&s information system is analyzed and improvement plans of SBA Integrated Information system is provided for efficient operation of SBA integrated Information system.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.2
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• pp.68-73
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• 2011

For the launch preparation of KSLV-I, gaseous nitrogen with various level of pressure and cryogenic liquid nitrogen are required. Nitrogen Supply System on launch complex has been developed to perform the production of high pressure gaseous nitrogen, the production of gaseous nitrogen with temperature of 273 ${\pm}$ 2K for protection purge of launch vehicle after loading of propellant and the supply of cryogenic liquid nitrogen for cooling of fuel (kerosene) and oxidizer (liquid oxygen). The operational instability of vaporizer mainly caused by its heat transfer characteristics which sensitively depends on the atmospheric conditions was removed by introducing parallel installation of two vaporizer and their switching operation. The developed Nitrogen Supply System carried out its function successfully in preparation of KSLV-I flight tests.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.1-8
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• 2001

Seismic design forces for bridge components may be determined by modifying elastic member forces of design earthquakes using appropriate response modification factors according to the national design code of bridges Modeling technique of pile foundation system is one of the important parameters which greatly affects the results in the process of the elastic seismic analysis of a bridge system with pile foundation. In this paper, a approximate and simplified modeling technique of a pile foundation system for the practical purposes is presented. The modeling technique is based on the stiffnesses of pile foundation during earthquake. The horizontal stiffnesses are determined from the resistance-deflection curves derived from the results of dynamic field tests using cyclic loads and the vertical stiffness includes the effects of the end bearing capacities and side friction of piles as well as the pile compliances under the expected vertical load level. The applicability of the proposed technique has been validated through the some example bridge analyses.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.488-492
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• 2010

In order to verify the performance of high-speed train and core equipments such as current collection system, sophisticated tests and evaluating procedures must be considered. In case of force sensor to test contact force of pantograph, it should customize the test instruments according to characteristics of pantograph. In this paper, the force sensor with a built-in strain-gauge which developed to improve measuring performance of contact force between the pantograph and catenary system is introduced. The test and evaluation results of force sensor's static and dynamic calibration with pantograph shows that its design is very suitable and applicable for on-line test. Henceforth, the force sensor will be applied to test interaction characteristics between the pantograph and catenary system on the high-speed line and expected by a part of measuring system for evaluating current collecting characteristics more reliably.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.497-502
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• 2020

For the Navy to acquire the desired vessels in time, it is necessary to plan the schedule accurately for warships. On the other hand, until now, there has been only a subjective prediction of the period of warship construction through a survey by a group of experts. No academic studies have been conducted based on actual data. Therefore, this study presents a model for predicting the construction period of a warship through linear regression based on actual data. Experts first identified the factors that can affect the warship construction period. Actual data of the factors were collected, and regression analysis was performed to estimate the ship construction period. As a result, the key factors selected that influence the construction period of a ship were the number of operational test items, number and type of equipment, and the number and type of R&D equipment. The resulting regression model revealed 96.5% accuracy in terms of internal validity.

• Journal of the Korean Society for Nondestructive Testing
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• v.17 no.1
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• pp.11-22
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• 1997

It is very essential to get the accurate classification of defects in primary pressure vessel and piping welds for the safety of nuclear power plant. Ultrasonic testing has been widely applied to inspect primary pressure vessel and piping welds of nuclear power plants during PSI / ISI. Classification of flaws in weldments from their ultrasonic scattering signals is very important in quantitative nondestructive evaluation. This problem is ideally suited to a modern ultrasonic Pattern recognition technique. Here, a brief discussion on systematic approach to this methodology is presented including ultrasonic feature extraction, feature selection and classification. A stronger emphasis is placed on Fuzzy-UTSCS (UT signal classification system) as efficient classifiers for many practical classification problems. As an example Fuzzy-UTSCS is applied to classify flaws in ferrite pressure vessel weldments into two types such as linear and volumetric. It is shown that Fuzzy-UTSCS is able to exhibit higher performance than other classifiers in the defect classification.