• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.2
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• pp.241-248
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• 1998

The accurate measurement of the room sound level is required in environment noise control. However, it has been found that the measurement system noise always corrupts the actual noise from the sound source. In this study, a new sound level measurement technique in which the system noise is eliminated from the measured signal by the cross spectrum method, is proposed. The received signals of two measuring microphones are recorded to DAT through the pre-amplifier and digitized by A/D converter. The cross spectrum calculated from the digitized signals gives the accurate sound level since the system noise is uncorrelated with the sound source noise which we want to measure. The performance of the proposed technique is verified experimentally to be effective and the technique is found to be economic since the low cost general purpose microphone could be used in this technique.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.55-59
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• 2008

It is very difficult to measure an accurate thrust for the performance test of liquid rocket engine. Liquid rocket engine is attached to the propellant feed system, control valve and many other safety systems. Without considering these effects, thrust data measured from the firing test is not reliable and meaningless. In this research, the modified thrust measurement system, which includes both all these side effects is developed for the verification of low thrust liquid rocket engine performance. In addition, reliability appraisal technique is studied to secure the reliability of thrust measurement system.

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.283-288
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• 1999

We investigated the characteristics of surface roughness evaluation using phase-measuring interferometer for a few ten $\AA$ and sub $\AA$-rough substrates. The influence of phase averaging and intensity averaging on the roughness measurement by phase measuring interferometer was investigated and the optimal number of phase and intensity averaging for the least measurement error was searched. For a few ten $\AA$-rough sample, roughness value did not depend so much on the data averaging. Whereas, measurement error for sub $\AA$-rough sample was significantly improved as the number of phase and intensity averaging increased. At the phase averaging of 30 and the intensity averaging of 20, roughness value that measurement error was minimized was obtained, and it was in good agreement with that by optical heterodyne interferometer. Roughness measurement at the optimal data averaging showed also good repeatability error less than 0.01$\AA$.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2037-2042
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• 2011

The railway electromagnetic environment is much more severe than most commercial and domestic environments. There are concerns about electromagnetic emissions from railways and their potential to interfere with the operation of commercial radio service and other equipment. EMC standards for railway applications are referenced as EN 50121 series and these standards describe the measurement method and specify limits for emission. However standard provide precise description of the general aspect of the measurement procedure and requirement of test equipments, making a reliable measurement of the radiated emissions from a train is a problem of balance between available observation time and the measurement time required by the characteristics of the measurement system. This paper focuses on the problem of measurement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.772-780
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• 2013

The high-altitude electromagnetic pulse(HEMP) conducted environment and the HEMP radiated environment are established as the consequences of a high-altitude nuclear explosion. The IEC 61000-2-10, the international standard, defines the HEMP conducted environment. The IEC 61000-5-5 defines how protective devices for conducted disturbance proposed for HEMP protection shall be specified. The IEC 61000-4-24 deals with methods for testing protective devices for HEMP conducted disturbance. The IEC 61000-4-24:1997 mainly describes the measurement method of small protective components. However, it does not provide the measurement method for a combination filter of a protective component and a filter which is widely used in recent. It is important to consider the characteristic of the measurement setup parameters like thickness and length of the cable and its height above ground plane etc. in establishing measurement setup because HEMP conducted disturbances include the frequency spectrum below 50 MHz. This paper deals with the optimized measurement method, considering the frequency spectrum of HEMP conducted disturbance, current waveform, and analyzing the effects of cables existing in the measurement setup.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.589-595
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• 2013

A reactor vessel internals comprehensive vibration assessment program(RVI CVAP) of an advanced power reactor 1400(APR1400) is being verified on the integrity of RVI for the design life of the plant by performing the non-prototype category-2 type on the US Nuclear Regulatory Commission Guide(NRC RG) 1.20, for which consists of a vibration and stress analysis program, a limited vibration measurement program, an inspection program, and the correlation of these programs. The aim of this paper is to describe the plan for the vibration measurement, test and acceptance criteria portion, and documentation and results of the APR1400 RVI CVAP. We will conduct the limited vibration measurement program of the APR1400 RVI CVAP according to the measurement plan and the vibration measurement testing in this paper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.9
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• pp.657-662
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• 2022

In this paper, the calculation using simulation and two measurement methods for G/T of the telemetry are analyzed. Antenna gain and noise temperature are calculated by using ICARA and Antenna Noise Temperature Calculator. System G/T were calculated by using Antenna gain/noise temperature, LNA gain/noise temperature, cable loss. The first G/T measurement method is Y-factor measurement method, which is to calculate G/T by comparing LNA noise temperature and a signal level difference when an antenna and a 50ohm termination are respectively connected to an LNA input terminal Second method is Solar calibration measurement method that is to calculate G/T by comparing noise level difference when looking at the sun and lowest level point. Finally, the accuracy was reviewed by comparing the G/T calculation results with the two measurement methods, and the optimal measurement method according to antenna performance and operating environment was presented.

• Smart Media Journal
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• v.13 no.2
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• pp.44-51
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• 2024

The construction of a stress measurement detaset plays a curcial role in various modern applications. In particular, for the efficient training of artificial intelligence models for stress measurement, it is essential to compare various biases and construct a quality-controlled dataset. In this paper, we propose the construction of a stress measurement dataset with quality management through the comparison of various biases. To achieve this, we introduce strss definitions and measurement tools, the process of building an artificial intelligence stress dataset, strategies to overcome biases for quality improvement, and considerations for stress data collection. Specifically, to manage dataset quality, we discuss various biases such as selection bias, measurement bias, causal bias, confirmation bias, and artificial intelligence bias that may arise during stress data collection. Through this paper, we aim to systematically understand considerations for stress data collection and various biases that may occur during the construction of a stress dataset, contributing to the construction of a dataset with guaranteed quality by overcoming these biases.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.109-117
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• 2005

Range and velocity measurement algorithm is a procedure for estimating the accurate target position by using matched filter outputs equally spaced both in range and doppler frequency domain. Especially, in measurement algorithm for multi-function radar, it is necessary to consider processing time as well as accuracy in order to track multi-targets simultaneously. In this paper, we analyze range and velocity measurement algorithm using discriminator estimation method which is a technique applied to angle measurement of monopulse radar. The applied method required constant processing time for estimation can be used in multiple target tacking. But, it is necessary to consider measurement accuracy because of using minimum channel outputs for estimation. In the simulation, we show that the applied method is superior to the traditional gravity center measurement algorithm with respect to the accuracy performance and also analyze the characteristics of the proposed technique by calculating RMS error level as the processing parameters such as pulse width , channel step, etc. change.

• The KIPS Transactions:PartC
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• v.18C no.1
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• pp.23-30
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• 2011

Recently internet protocol television (IPTV) service is becoming a typical emerging service enabled on broadband networks. Through the Internet which cannot support quality of service (QoS) beyond best-effort (BE) policy, how to manage and maintain its service quality is an important and essential issue for successful deployment and settlement of IPTV service. In particular, the current measurement scheme that mostly depends on specific equipments should be replaced with one that supports realtime and constant measurement achieved on a user's own will. Therefore, this paper proposes a scheme so-called 'user centric realtime measurement' of IPTV service. The developed software, which is installed in a set-top box (STB) at a user's premise, measures and reports the quality of IPTV service in realtime. In order to verify the performance and accuracy of the developed software, a number of tests are performed comparing to the measurement values from two major measurement equipments. The result of the tests shows that the measurement by the implemented software is significantly reliable.