Daewoong Kim’s research while affiliated with Korea Hydro and Nuclear Power - Central Research Institute and other places

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Publications (2)


A Study on the Actuator Efficiency Behavior of Safety-Related Motor Operated Gate and Globe Valves
  • Chapter

September 2011

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59 Reads

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2 Citations

Nuclear Engineering and Design

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SungKeun Park

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DoHwan Lee

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[...]

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DaeWoong Kim

Periodically, the operability of the safety-related motor-operated valves (MOVs) in nuclear power plants must be verified. Because the actuator efficiency is one of the most important factors in the determination of the actuator output, it should be considered in ensuring the operability of MOVs during the verification duration. In particular, special consideration should be paid to its potential degradation, but the design efficiency provided by manufacturers is usually used because the actuator efficiency calculation is difficult and requires considerable time and effort. In this paper, a method is introduced to calculate actuator efficiency by using diagnostic signals acquired in field tests. The actuator efficiency was calculated from the estimated motor torque, the stem thrust measured in field tests, and overall gear ratio provided by manufactures. The motor torque was estimated by using an algorithm, which can calculate electric torque from the three phases of currents and voltages, resistances between phases acquired in field tests. The validation of the design efficiencies was evaluated by comparing those efficiencies with the calculated actuator efficiencies. And, the age-related degradation was analyzed through the behavior analysis over time of the calculated actuator efficiencies. Most of the actuator efficiencies were found not to be degraded over time and kept efficiency greater than the design efficiency. However, two actuator efficiencies with lower motor speed, overall gear ratio, and maximum motor torque rating are susceptible to be lower than the design efficiencies. For the two actuators, threshold efficiencies were calculated and provided to replace their design efficiencies.


A study on the stem friction coefficient behavior of motor-operated valves

March 2011

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22 Reads

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1 Citation

Nuclear Engineering and Design

This paper describes how to calculate the stem friction coefficient of safety related motor operated valves (MOVs) that reflects potential degradation with time by using diagnostic signals acquired in static field tests that have been conducted more than two times per valve. Based on the calculated stem friction coefficients, their behaviors with time were analyzed considering various parameters that could cause potential degradation. Most friction coefficients change randomly rather than increasing or decreasing continuously over time. From those trends, a threshold coefficient, which represents the highest expected value of the friction coefficient, was calculated and provided.

Citations (1)


... This fact implies that Φ(e) always lies between the two straight lines k 1 e and k 2 e in the first and third quadrants. Inequality(8) can be simply written as Φ∈[k 1 ,k 2 ]. ...

Reference:

A Nonlinear PD Controller Design and Its Application to MOV Actuators
A study on the stem friction coefficient behavior of motor-operated valves
  • Citing Article
  • March 2011

Nuclear Engineering and Design