• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.375-381
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• 1999

In this study, turbine speed control algorithm is studied for Buk-Jeju steam turbine power plant and also digital governor system is designed for speed control of steam turbine in power plant. By using duplex I/O module, triplex CPU module, 2 out of 3 voting algorithm and adding self diagnostic ability, the reliability of the designed digital governor system can be acquired satisfactorily. Designed and manufactured digital governor system is implemented in a pilot steam turbine plant of 0.3kw output power Installed in Korea Maritime University. After a series of experiment the reliability and availability is confirmed and also stable operation is achieved.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.402-405
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• 1997

The analysis of heart sounds is a noninvasive diagnostic method useful to diagnose heart valve function. In this paper we compared the ability of spectral analysis method for prosthetic heart valve sounds. Phonocardiograms of prosthetic heart valve were analyzed in order to derive frequency domain feature suitable for the classification of the valve state. The FFT-based methods did not provide sufficient frequency resolution to completely characterize the spectrum of prosthetic heart valve sounds. A high resolution parametric methods were shown to give superior frequency resolution. In parametric methods, all methods provide a 1st & 2nd & 3rd frequency component. But Shank method provided a most dominant frequency peak.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.1
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• pp.138-145
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• 2000

This paper presents a robust fault diagnosis and fault tolerant control method for the control systems in closed-loop affected by unknown inputs or disturbances. The fault diagnostic scheme is based on the disturbance-decoupled state estimation using a 2-stage state observer for state, actuator bias and sensor bias. The estimated bias show the occurrence time, location and type of the faults directly. The estimated state is used for state feedback to achieve fault tolerant control against the faults. Simulation results show that the method has definite fault tolerant ability against actuator and sensor faults, moreover, the faults can be detected on-line, isolated and estimated simultaneously.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.2
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• pp.199-204
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• 2013

Recently, the demand for fuel efficient electric vehicles (EVs) and hybrid electric vehicles (HEVs) has been growing globally. Due to the increased number of switching devices in the electrified vehicles, the probability of the semiconductor device failure is much higher than in other application areas. A sudden failure in one of the power switches and insufficient power management ability in the systems not only decreases system performance, but also leads to critical safety problems. In this paper, novel switch open circuit fault detection method is proposed, and the proposed approach is verified by experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.130-130
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• 2000

This paper presents a robust fault diagnosis and fault tolerant control lot the actuator and sensor faults in the closed-loop systems affected by unknown inputs or disturbances. The fault diagnostic scheme is based on the residual set generation by using robust Parity space approach. Residual set is evaluated through the threshold test and then fault is isolated according to the decision logic table. Once the fault diagnosis module indicates which actuator or sensor is faulty, the fault magnitude is estimated by using the disturbance-decoupled optimal state estimation and a new additive control law is added to the nominal one to override the fault effect on the system. Simulation results show that the method has definite fault diagnosis and fault tolerant control ability against actuator and sensor faults.

• Korean Journal of Head & Neck Oncology
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• v.3 no.1
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• pp.79-83
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• 1987

Carotid body tumor is rare tumor in the neck. Among the pathologic conditions affecting paraganglionic tissue. the carotid body is most frequently involved. There are controversies in terms of natural history. biological behaviors, technique of excision, risks of the operation. Carotid angiography is the most valuable diagnostic aid and important for the planning of therapy. Definite treatment of carotid body tumor is surgical excision. Considerable degree of caution and vascular surgical armamentation are required because of its anatomical location and profuse vascularity. Surgical removal of this kind of paraganglioma must be predicated upon several factors such as tumor character. location. symptom, vascularity, and surgeon's ability.

• Korean Medical Education Review
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• v.15 no.3
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• pp.112-119
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• 2013

Most medical colleges in Korea have been shifting from traditional education to outcome-based education, which is the general trend in medical education. The purpose of this study was to make some suggestions in light of the reality and challenges of student assessment in medical education from the perspective of outcome- based education. First, those who are responsible for student assessment should be diversified to include faculty, residents, students, and evaluation committee members. They need separate roles in educational evaluation, so evaluation competencies are required for them. Second, various methods for evaluation and score interpretation can be used for effective evaluation. We can adopt diagnostic, formative, and summative evaluation functionally, and the norm-referenced, criterion-referenced, growth-referenced, and ability-referenced evaluation based on criteria for score interpretation. Finally, various evaluation domains and test forms can be administered together in the common lectures in the medical school. We can test not only knowledge but also skills and attitudes, with diverse test forms such as supply and performance types.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.7-20
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• 1999

Magnetic resonance imaging with its superior soft tissue contrast resolution and absence of beam hardening artifacts, combined with its ability to perform multiplanar imaging, is now effective tool in diagnostic imagings. Magnetic resonance is primarily a phenomenon that involves atomic nuclei. It provides totally new clinical informations with no known hazards through the use of very weak interactions with endogenous stable magnetic atomic nuclei. This article briefly summarizes the basic mechanism of generation and detection of the signals and general sorts of tissue properties which can influence the signals and thereby give rise to tissue contrast. It also describes how the machine-operating parameters can be used to manipulate the tissue contrast observed in the image.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.21-23
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• 1994

A Fault Detection. Isolation scheme based on ANN(Artifical Neural Network) is proposed for the supervision of a DC shunt motor. The Proposed FDI scheme can promptly detect the occurence of fault and classify all the faults that may occur during the operation. Also. it covers the full operating range in spite that the mathematical model of the motor contain strong nonlinearities. The simulation results show that the FDIU has good diagnostic ability even in the noisy environment.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.689-691
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• 1995

In this paper, a fault detection and isolation unit(FDIU) for a centrifugal pump system driven by DC-motor is proposed. The proposed scheme can be classified into the dedicated observer scheme(DOS). A fuzzy logic based inference engine is adopted for the isolation of each faults. Having the fuzzy inference engine, the proposed FDIU resolve a few important problems of the conventional DOSs with conventional two valued logic. The ouputs of the proposed FDIU are not "ith fault occurred" but the grade of memberships that indicate the consistency of observered symptoms(residuals) with each fault symptoms stored in the rule base. The ouputs can easily be transferred to the ranking of the fault possibilities and it will provide very useful informations in monitoring the process. The simulation results show that the FDIU has very good diagnostic ability even in the noisy environment.