• Journal of Chest Surgery
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• v.15 no.4
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• pp.394-401
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• 1982

Recently, 4 cases underwent successful surgical correction of tetralogy of Fallot combined with pulmonary atresia in 2 cases, with abnormal coronary artery in another 2 cases. The operation consisted of a patch repair to the ventricular septal defect. The pulmonary atresia and stenosis were corrected with the method of external connection, from the right ventricle to the pulmonary artery using the valved conduits.

• International Journal of Control, Automation, and Systems
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• v.6 no.5
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• pp.670-676
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• 2008

While the matrix converter has many advantages that include bi-directional power flow, a size reduction, a long lifetime, and sinusoidal input currents, it is vulnerable to the input voltage disturbances, because it directly exchanges the input voltage to the output voltage. So, in this paper, a critical evaluation of the effect of various abnormal voltage conditions like unbalanced power supply, balanced non-sinusoidal power supply, input voltage sags and short time blackout of power supply on matrix converter fed induction motor drives is presented. The operation under various abnormal conditions has been analyzed. For this, a 230V, 250VA three phase to three phase matrix converter (MC) fed induction motor drive prototype is implemented using DSP based controller and tests have been carried out to evaluate and improve the stability of system under typical abnormal conditions. Digital storage oscilloscope & power quality analyzer are used for experimental observations.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.3
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• pp.97-103
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• 2018

This paper addresses an improved naval combat UPS(Uninterruptable Power Supply) system under abnormal transients. Previously, thermistor and varistor elements were used to cope with transient overvoltage and overcurrent, however the UPS was frequently unavailable because it was vulnerable to abnormal transient voltage generated during system operation. In order to overcome this problem and protect UPS system, this paper proposes an input power cut-off circuit that detects the initial input power and abnormal transient voltage generated during operation, improvement of power control sequence, and a method to prevent malfunction of an inverter and CPU. The UPS system implementing the proposed method was simulated by input power variable test using programmable AC/DC generator, and finally validated its reliability and stability through field tests by mounting on multifunctional console of naval combat system.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.57-63
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• 2022

This study describes a system that monitors the tool and cutting state of automatic beveling operation in real time. As a signal for cutting state monitoring, a motor current detected from the spindle drive system of the automatic beveling machine is used to monitor abnormal state. Because automatic beveling is processed using a face milling cutter, the cutting force mechanism is the same as the milling process. The predicted cutting torque is obtained using a cutting force model based on specific cutting resistance. Then, the predicted cutting torque is converted into the spindle motor current value, and cutting state stability is diagnosed by comparing it with the motor current value detected during beveling operation. The experimental results show that the spindle motor current can detect abnormal cutting state such as overload and tool wear during beveling operation, and can diagnose the cutting stability using the proposed equip-current line diagram.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.10a
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• pp.89-92
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• 2000

The purpose of this thesis is to investigate the information content of commercial paper credit rating changes of Korean firms. The result shows neither sinificant daily abnormal returns nor significant cumulative daily abnormal returns over the test window. This ind icates that commercial paper rating changes are not informative to investors. A sensitivity analysis conducted for the portfolio of subsample shows a similar result. This thesis, however, may contribute to the better operation of Korean financial market by providing several directions to establish credit-based financial transactions.

• Journal of Chest Surgery
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• v.13 no.4
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• pp.442-447
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• 1980

A 8-year-old boy underwent surgical correction of complete transposition S.D.D. of great arteries combined with subaortic ventricular septal defect and pulmonary stenosis [infundibular and valvular]. The operation consisted of an internal baffling connecting the left ventricle to the aorta through the ventricular septal defect. The pulmonary stenosis was corrected with the method of external connection, the right ventricle to the pulmonary artery using the conduit valve [20 mm] contained Hancock due to abnormal distribution of left coronary artery of which conduit due to abnormal distribution of left coronary artery of which the circumflex branch crossed the portion of right ventricular outflow tract. This case was suitable for corrective surgery-Rastelli operation-and the patient`s condition in very good until present [post-operative 5 months].

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.1 no.1
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• pp.123-132
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• 2002

In this study, the static and dynamic characteristics of endmilling process was modelled and the analytic realization of chatter mechanism was discussed. In this regard, We have discussed on the comparative assessment of recursive time series modeling algorithms that can represent the machining process and detect the abnormal machining behaviors in precision endmilling operation. In this study, simulation and experimental work were performed to show the malfunctional behaviors. For this purpose, new recursive least square method (RLSM) were adopted for the on-line system identification and monitoring of a machining process, we can apply these new algorithms in real process for detection of abnormal chatter. Also, The stability lobe of chatter was analysed by varying parameter of cutting dynamices in regenerative chatter mechanics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.971-974
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• 2001

In this study, the static and dynamic characteristics of endmilling process was modelled and the analytic realization of chatter mechanism was discussed. In this regard, We have discussed on the comparative assessment of recursive time series modeling algorithms that can represent the machining process and detect the abnormal machining behaviors in precision endmilling operation. In this study, simulation and experimental work were performed to show the malfunctional behaviors. For this purpose, new recursive(RLSM) were adopted for the on-line system identification and monitoring of a machining process, we can apply these new algorithms in real process for detection of abnormal chatter. Also, the stability lobe of chatter was analysed by varying parameter of cutting dynamices in regenerative chatter mechanics.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.366-369
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• 1997

In this study, we measured upper right, lower right, upper left region to find the optimal region which represent liver function. We found that the upper right region is optimal because of high accuracy and low standard deviation. For normal subjects all the calculated HEFs were greater than 100% and all those of abnormal ones were less than 80%. Thus HEF can be assumed to discriminate abnormal livers from normal ones. It was found that the patients with surgical operation would survive if both the pre-and the post-operative HEFs are greater than 50%. Therefore HEF method can be a good estimator for surgeon to determine the surgical operation and to evaluate remaining hepatic function after surgery as well as it is reliable and simple.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.101-105
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• 2021

Encouragement of DER from Korean government with several policies boosts DER installation in power system. When the penetration of DER in the grid is getting high, loss of generation with break-away of DER by abnormal grid conditions should be considered, because loss of high generation causes abnormal low frequency and additional operations of protection system. Therefore, KEPCO where is Korean power utility is preparing improvement in regulations for DERs connected to the grid to support abnormal grid conditions such as low and high frequencies or voltages. This is called 'Ride Through' because the requirement is for DER to maintain grid connection during required periods when abnormal grid conditions occur. However, it is not easy to have a test for ride through capability in reality because emulation of abnormal grid conditions is not possible in real power system in operation. Also, it is not easy to have a study on grid effect when ride through capability fails with the same reason. PHILs (Power Hardware In the Loop System) makes it possible to analyze power system and hardware performance at once. Therefore, this paper introduces PHILs test methods and presents verification of ride through capability especially for low voltage grid conditions.