• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.79-80
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• 2014

Voltage source multilevel module converter attracts more and more attention recently. The core component of the voltage source multilevel module converter is the valve based on IGBT. So the test circuit for the valve is very important, reliable test method can guarantee the converter valve design meet the operation requirement. This paper analyzes the valve voltage and current stress during the operation, and according to IEC standard test requirement, object, condition, introduces a kind of test circuit. Finally, through the simulation model, to verify the test circuit can provide the proper test condition for the voltage source multilevel module converter valve.

• Speech Sciences
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• v.1
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• pp.237-259
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• 1997

Cleft Palate speech appears to have hyper/hyponasality with velopharyngeal insufficiency and articulation disorders. Previous studies on Cleft Palate speech have shown that speech tends to have lower airflow and air pressure. To examine the aerodynamic characteristics of Cleft Palate speech, Aerophone II Voice function Analyzer was used. We measured sound pressure level, airflow, air pressure and glottal power. Three Cleft Palate adults and five normal adults participated in this experiment. The test words are composed of: (1) the sustained vowel /o/ (2) /CiCi/, where C is one of three different stop consonants in Korean (3) /bimi/. Subjects were asked to produce /bimi/ five times without opening their lips. All the data was statistically tested by t-test for Cleft Palate patients before operation groups and control groups and paired t-test for Cleft Palate patients before and after operation groups. The results were as follow: (1) Cleft Palate patients generally speak with incomplete oral closure and lower oral air pressure. As a result, the SPL of Cleft Palate before operation is 3 dB lower than control groups. (2) Airflow of Cleft Palate in phonation and articulation is lower than that of control groups. However, it increased after operation. Lung volume and mean airflow in phonation are significantly increased (p<0.05). (3) Although velopharyngeal function (velar opening rate) of Cleft Palate is poor in comparison with control groups, it was recovered after operation. In this event maximum flow rate and mean airflow rate are significantly increased (p<0.05). (4) Air pressure of Cleft Palate in speech is lower than that of control groups. In general, the air pressure of Cleft Palate increased after operation. In this event air pressure of glottalized consonant is significantly increased (p<0.04). (5) Glottal Power(mean power, mean efficient and mean resistant) of Cleft Palate patients is lower than that of control groups. But mean efficient and mean resistant of Cleft Palate patients increased significantly (p<0.05) after operation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.177-180
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• 2006

It is essential for engine design and establishment of test program to assign an appropriate performance range of liquid propellant rocket engine(LRE). The present study surveys the operation and qualification test range of LRE developed in Japan, United States, Europe and Russia.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.265-268
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• 2005

This paper discusses a strategy and status for development and operation of durability mock-up test facilities for offshore structures. The strategy is examplified and facilitated using an offshore transmission tower crossing the West sea and the Shihwha lake, which was designed and constructed 345kV T/L lines transmitting power from Yeong-Heung fossil power plant to Seoul metropolitan area. Various data for corrosion protection, aging, life-prediction of concrete and steel offshore structures can be obtained using the proposed mock-up test facility. Acquired data will be used for further research on durability, life-prediction, and retrofit of structures. It is important to maintain the safety of 345 kV Yeong-Heung transmission line crossing the Shihwha lake because the offshore structure is one of the critical electric facilities transmitting large power to the metropolitan area. Operation of the offshore transmission tower mock-up is expected to make a significant contribution to stable power supply.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1601-1602
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• 2007

Steam stop valves of steam turbine in the power plant are at their 100% position and have no movements. Steam control valves, ie governor valves have no movements either at their controlling position on load limit operation. By the way, if there were no change of operation state, steam valves could be sticked mechanically. Because the governor could fail in protecting and controlling steam turbine in case of emergency conditions, the closing test of 100% valve travel must be accomplished periodically for the purpose of testimony of their good conditions. And, As the difference between steam turbine structures exists according to the manufacturer or generation capacity, both steam stop valves and steam control valves differes in structure and operation method. Therefore, it is essential for not only turbine protection but also control for the control engineers to find out composition of steam valves and method of closing test.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.1
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• pp.43-50
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• 2009

The characteristics at the intermediate operation point of the turbopump-gas generator(TP-GG) coupled test were investigated by analytical method. The pump outlet pressure, gas generator mixture ratio, gas generator pressure, and temperature were examined considering risk minimization of test. The engine system shows different behavior from the TP-GG coupled test at the intermediate operation point since the combustion pressure feeds back to the flow rate in the lines. The advanced valve changes in the combustor line helps less risky mode transition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.703-712
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• 2014

To improve the efficiency and safety of railway systems, the train control system has been considerably evolved from the ground-equipment-based control system (e.g. track circuit, interlocking system, etc.) into the on-board-equipment-based control system. In addition, this train control system enables the rolling stock to intelligently control the trackside facilities by introducing the information and communication technologies (ICT). Accordingly, since the ICT-based train control system makes the railway system be simplified (i.e. the heavy ground-equipment can be removed), the efficient and cost-effective railway system can be realized. In this paper, we perform the feasibility test of the ICT-based train control system via a simulation. To this end, we have developed the prototypes of the on-board controller and wayside object control units which control the point and crossing gate and performed the integrated operation simulation in a testbed. In this paper, before the field test of the on-board-controller-based train control system, we perform the Consecutive operation test for prototypes of the on-board controller, wayside object control units and local control computer.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.811-816
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• 1992

The objective of cell operation in CIM is to maximize system efficiency, not the cell itself. We introduce a cell operation scheme that pursues the direction. For specific cases, work center and AS/RS are closely investigated. Structures of their operation mechanism and methods of job scheduling are introduced along with an expert system developed for the scheme. The cell operation softwares developed are now under test at K.U.FMS, a model CIM plant.

• Journal of Information Technology Services
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• v.17 no.1
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• pp.155-170
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• 2018

This study examines a data-driven approach for software test automation at an online shopping site. Online shopping sites typically change prices dynamically, offer various discounts or coupons, and provide diverse delivery and payment options such as electronic fund transfer, credit cards, mobile payments (KakaoPay, NaverPay, SyrupPay, ApplePay, SamsungPay, etc.) and so on. As a result, they have to test numerous combinations of possible customer choices continuously and repetitively. The total number of test cases is almost 584 billion. This requires somehow automation of tests in settling payments. However, the record playback approach has difficulties in maintaining automation scripts due to frequent changes and complicated component identification. In contrast, the data-driven approach minimizes changes in scripts and component identification. This study shows that the data-driven approach to test automation is more effective than the traditional record playback method. In 2014 before the test automation, the monthly average defects were 5.6 during the test and 12.5 during operation. In 2015 after the test automation, the monthly average defects were 9.4 during the test and 2.8 during operation. The comparison of live defects and detected errors during the test shows statistically significant differences before and after introducing the test automation using the data-driven approach.

• Journal of Aerospace System Engineering
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• v.7 no.3
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• pp.45-50
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• 2013

This is a research report about the method of how to maintain qualification of certification flight test crews. KCA(Korea Certification Agency) have completed the KC-100 airplane certification flight tests which is the first time experienced flight tests operation. After the certification flight test, it has been found that annual flying time requirement of 100 hours to the certification flight test pilot is too strict, and other several requirements to maintain the qualification of the certification test crew such as aircraft certification introduction training, initial flight test pilot and flight test engineer certification training, crew resource management training, aviation physiology training, and survival training was difficult to implement in Korean civil aviation environments. In this study, it was suggested that 30 hours of flying time for maintaining certification flight test pilot qualification could be applied to contribute for safe operation of certification flight test and the other training requirements of the certification flight test crew could be fulfilled using self made training courses, existing FAA training courses and Korean Air Force training resources. Therefore, it is recommended that the regulation of maintaining the certification flight test crew qualification should be refined to implement the requirement practically.