• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1131-1137
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• 2005

Methods for measuring surface roughness based on light reflectivity have advantages over methods based on light interference or diffraction, especially in in-situ, on-the-machine and in-process applications. However, measurement inconsistencies caused by changes in the specimen are still a drawback for field applications. In this study, we propose a new feedback-based algorithm to enhance the consistency against changes in the specimen. The algorithm is deduced from simulations based on light reflectance theory with typical modeled surfaces. The proposed method is similar to a digital controller and regulates the power of reflected light. Experiments varying heights and materials, verified the improvements in robustness of the method against measurement disturbances caused by specimen changes.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권10호
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• pp.568-572
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• 2002

High precision voltages, currents, and electrical power measurements in wide range of frequency can be achieved by using the thermo-elements(thermal converters). This paper describes a development wattmeter, based on a thermal principle. The instrument has been performed measurement in the range of currents from 0 to 50 A, voltages up to 480 V, power factor 0.5 (lag, lead), 1 and frequencies from 60 Hz to 3 KHz. It is intended to be used by electric utilities, standard laboratories, testing laboratories, and applications where high measurement accuracy are attractive consideration.

• 산업기술연구
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• 제30권A호
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• pp.83-88
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• 2010

Recently, the LED lighting is widely used to illumination purpose due to its high luminous efficiency and the long life time. However, the light power and lifetime is reduced by junction temperature increment of LED. So it is important to measure the junction temperature accurately. In this paper, we proposed a new design and implementation method of high power LED junction temperature measurement circuit. The proposed circuit has two current sources which are a driving current source and a measurement is verified by experiment, and the result shows that the proposed circuit is appropriate to practical use.

• 한국IT서비스학회지
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• 제18권3호
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• pp.53-74
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• 2019

In this paper, a theoretical measurement model for comparing cultural power of nations as a form of national power is built and applied to the G20 nations. The measurement model is drawn from the literature of the state theories regarding culture, theories of epistemology, and debates about the sources of national power. Taking the multiple indicator approach, indicators reflecting diverse aspects of cultural power are developed are developed. Examined with empirical data, this model is proved as appropriate as a tool for measuring and comparing the cultural power of nations. Diverse aspects of the cultural power of the G20 nations are ranked and interesting points regarding the state and potential of Korean culture and her cultural governance in these respects are elaborated. The overall ranking of the cultural power of Korea is found as the $11^{th}$ while the U.S., U.K. and France respectively as the $1^{st}$, the $2^{nd}$, and the $3^{rd}$. The U.S. is ranked as the 1st in all three aspects of the cultural power of nation: cultural attractiveness, efforts to enhance the national cultural power, and cultural base of a nation. Korea is ranked as $14^{th}$, $11^{th}$, and $6^{th}$ respectively in these three respects of the national cultural power. Based upon typological analysis of the cultural power of Korea, it is found that Korea belongs to Type III. Trying to move eventually toward Type I state via Type II is suggested as a strategy movement for future cultural governance by Korean government and people to enhance her national cultural power.

• 한국유체기계학회 논문집
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• 제2권2호
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• pp.19-26
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• 1999

Thermal output in a nuclear power plant is verified with calorimetric heat balance on the secondary plant. The calorimetry involves the precise measurement of the feedwater flow rate. However, the correct indication of feedwater flow rate obtained by a pressure-difference measurement across a venturi can be affected by instrument errors, fouling or a poorly developed velocity profile. This can result in an inaccurate mass flow rate and consequently an inaccurate estimate of power. The purpose of this study is to develop verification methods with accuracy better than $0.5\%$ for high precision flow measurement to be used for measuring feedwater flow rate. This chemical tracer method is a testing process that uses tracers which can be applied to quantify losses in electrical output due to the incorrect measurements of feedwater flow rate. And this system has good response to the variation of the flow rate. Accuracy of better than 0.5 percent can be expected for feedwater flow measurement, providing that the system can be stabilized during the test. This methodology is applicable to other flow systems well.

• 전기학회논문지
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• 제67권7호
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• pp.816-823
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• 2018

The Auto-synchronizer is essential equipment for synchronizing a generator to the power system. It is performing that measurement of the magnitude, frequency and phase of the voltage signal of the power system and generator. It is important to select the appropriate measurement algorithm for preventing various problem such as mechanical stress and Electrical problem. Teager Energy Operator(TEO) and Discrete separation algorithm(DESA) is measurable the instantaneous parameters of a sine wave using 5 samples and can be measured at a fast and with a simple operation. Therefore it has many advantages in measuring the parameters. In this paper, it confirmed measurement results using matlab simulations when there are synchronized in order of frequency, magnitude. Also it presented methods using digital filters and sample intervals to improve accuracy.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.163-167
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• 2009

Although the domestic electric power consumption of lighting have shared 20${\sim}$30 % of the national electric power consumption, the spread of lighting control system which can reduce the electric power consumption have been insignificant. The government have set the demonstration project and given the incentive to promote the spread of lighting control system since 2008. The M&V (Measurement and Verification) methodology for lighting control system have not been set yet in our country, but the direct measurement was suggested in US. The direct measurement methodology can increase the accuracy of measurement, but it cost much money to burden a customer. This study have suggested a new M&V methodology which cost low and is simple relatively. I had measured the amount of electric consumption through both the direct measurement and the new M&V program computation, and have analyzed the deviation. The amount of electric consumption measured by the new M&V program computation have agreed with one by the direct measurement within the error range of the instrumentation in case of lab scale test, and the 4${\sim}$8 % deviation have existed in case of field evaluation.

• KEPCO Journal on Electric Power and Energy
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• 제3권1호
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• pp.9-16
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• 2017

The performance test is conducted for the purpose of determining the accurate thermal performance of the power generation facility or deriving the factors of thermal efficiency degradation. Compared to the acquisition method of power plant thermal performance test data by compensating cable or transmission cable, performance test using wireless instrument can acquire digital data in order to shorten the period due to installation and demolition of instrument and enhance safety of workers and relatively accurate data can be acquired thereby improving work efficiency. Wireless instruments have already been introduced to the market a long time ago, and some of them are used in industry such as petrochemical industry. However, there is no example which has been conducted for performance test of power generation facilities. In order to apply power generation facilities, a reliable system capable of acquiring performance data smoothly without affecting the control system is required. The wireless measurement system can eliminate the measurement defects and errors such as the damage due to the movement of the connecting cable, the extension due to the extension of the shield wire, the contact failure at the contact point between the measuring sensor and the connecting wire, This method has the advantage of collecting relatively accurate performance test data.

• 조명전기설비학회논문지
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• 제18권1호
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• pp.60-66
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• 2004

전기부하설비의 전압, 전류, 전력, 고조파 등의 분석을 위해서는 수학적 모델링 보다는 실제 계측을 통한 전력분석이 필요하고 이를 통해 전기설비의 효율적인 관리, 에너지 절약 및 사고 예방에 필요한 대책을 수립할 수 있다. 특히 비선형 부하에 의해 발생되는 고조파의 대책수립을 위해 계측을 통한 전력분석이 필수적이다. 따라서 본 논문에서는 전기부하설비에 공급되는 전력을 측정하고 분석할 수 있는 저가형 데이터 획득 시스템을 DSP 기반으로 개발하였고 이를 실제 전력계통에 설치하여 전력 및 고조파의 측정과 분석을 수행함으로써 그 성능을 입증하였다.

• ETRI Journal
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• 제40권1호
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• pp.26-38
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• 2018

To overcome considerable path loss in millimeter-wave propagation, high-gain directional beamforming is considered to be a key enabling technology for outdoor 5G mobile networks. Associated with beamforming, this paper investigates propagation power loss characteristics in two aspects. The first is beamwidth effects. Owing to the multipath receiving nature of mobile environments, it is expected that a narrower beamwidth antenna will capture fewer multipath signals, while increasing directivity gain. If we normalize the directivity gain, this narrow-beamwidth reception incurs an additional power loss compared to omnidirectional-antenna power reception. With measurement data collected in an urban area at 28 GHz and 38 GHz, we illustrate the amount of these additional propagation losses as a function of the half-power beamwidth. Secondly, we investigate power losses due to steering beam misalignment, as well as the measurement data. The results show that a small angle misalignment can cause a large power loss. Considering that most standard documents provide omnidirectional antenna path loss characteristics, these results are expected to contribute to mmWave mobile system designs.