• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.669-672
• /
• 2002

Establishment of the Quantum Hall Resistance(QHR) Standard as national resistance standard using a room temperature DCC resistance bridge is described. A simple method are used to obtain the current dependence and error of 10: 1 ratio of the bridge instead of the method using a cryogenic resistance bridge. Measurement uncertainty of the system is estimated as $0.14{\times}10^{-6}$ and it is confirmed that the QHR standard is agreed well with the QHR of other NMIs using the cryogenic resistance bridge within the uncertainty, More improvement about performance of the QHR device and 10: 1 ratio accuracy is still under progress.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.4
• /
• pp.241-247
• /
• 2010

This study aims to investigate and improve the present state of technical standard on building mechanical system in Korea. At this point be tormented the energy depletions are big problem on the rise. Building mechanical system is configured air conditioning, sanitation, urban equipment. In the design of equipment, installation, maintenance, applies to all devices in the field of industrial equipment and general engineering equipment field are within bounds to say that all of the equipment field. However, domestic technology level is still fly short of international standards in architecture, we spent much energy. Because of this, find the current situation and identify the problems look up ways to improve them.

• International Journal of Internet, Broadcasting and Communication
• /
• v.7 no.2
• /
• pp.90-95
• /
• 2015

This paper describes IEC 61727 standard of Photovoltaic (PV) systems -Characteristics of the utility interface. IEC 61727 standard tests include utility compatibility and personnel safety and equipment protection of PV inverter performance functions. Especially utility compatibility part includes test items of 1) voltage, current and frequency, 2) normal voltage operating range, 3) flicker, 4) DC injection, 5) normal frequency operating range, 6) harmonics and 7) waveform distortion, 8) power factor of PV inverter. Also personnel safety and equipment protection part includes test items 1)loss of utility voltage, 2)over/under voltage and frequency, 3)Islanding protection, 4)response to utility recovery, 5)earthing, 6)short circuit protection, 7)Isolation and switching of PV inverter. In this paper, each item of IEC 61727 standard test is studied and analyzed and finally full tested by PV inverter performance function.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.1
• /
• pp.53-60
• /
• 1995

The aims of this study are to evaluate the measurement capability of the electromagnetic power and to understand the current state of standard maintanance of the eight participants among the thirteen national calibration and test organizations. The calibration factors were measured at six test frequencies, 50, 100, 500, 1000, 5000, 10000 MHz by organizations and KRISS on the basis of round robin test. The results were analyzed by calculating the standard deviation of the measured values from the standard values. The analysis shows good agreement within 1.0% for all participants at the measurement frequencies. Therefore, the measurement capability of all participants is good in the frequency range of 50 MHz to 10 GHz. For the four participants which specified standard deviations of repeated measurements in their reporst, the total uncertainties is less than 1.9% at the measurement frequencies.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.4 no.1
• /
• pp.54-62
• /
• 1990

This paper shows a reasonable design standard of Demand Factor and Diversity Factor for buildings, that was made by the systematic and statistical way considering actual conditions, such as investicated electric equipment capacity, electric power consumption, etc. The saving of electric equipment investment, the decrease of power loss, the improvement of facilities utilization and the decrease of electric power rates, can be contributed by the application of the design standard. The recommended design standard must be applied by the revision of current regulations and laws.

• Journal of Korean Society for Quality Management
• /
• v.34 no.4
• /
• pp.125-132
• /
• 2006

An adjusted control limit of the $\overline{X}$ chart is proposed for monitoring the continually improving processes. The continual improvement of the process implies the decrease of the process variance, which is represented by a logistic curve. The process standard deviation is estimated by the exponentially weighted moving average of the sample standard deviations from the past to the current times. The control limits are adjusted by the estimated standard deviation at every sampling time. The performance of the adjusted control limit is compared with that of the standard control limits for various cases of the decreasing speed and size of the variance. The results show that the $\overline{X}$ chart with the adjusted control limits provides better performances for monitoring the small and moderate shifts in continually improving processes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.9
• /
• pp.108-117
• /
• 2010

The main contents of this paper are the PQM system construction case and distribution system harmonic voltage analysis. The PQM system has constructed by KEPCO in order to investigate power quality of distribution power system for new power quality standard of KEPCO. In result, we have confirmed that voltage harmonic measurement value of the high voltage contract customer 8 households is suitable the KEPCO harmonic standard tentative plan. And the voltage harmonic value of distribution line end side is not always more high than source side by harmonic current offset effect. In the future, acquired data by season, region, load from the PQMS will be used on the resonable harmonic standard enactment in KEPCO.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.11a
• /
• pp.98-99
• /
• 2014

Construction equipment cost is critical to estimate the total construction costs, particularly in large and complicated projects. Despite its importance, the construction equipment cost may not reflect the current market value since the equipment database is being updated every 6 years at most. To keep construction equipment cost up to date, it is highly recommended to use the standard market price that is reported each year by the Ministry of Security and Public Administration (MOSPA). However, there is still a gap to adopt the standard market price system for the construction equipment cost computing system. Therefore, this paper suggests an effective way to develop a construction equipment cost estimation system.

• Ocean Science Journal
• /
• v.42 no.1
• /
• pp.19-30
• /
• 2007

This study analyzed the current meter records along with wind records for over 500 days obtained in the Kangjin Bay, South Sea, Korea spanning from March, 2003 to Nov. 2005. Various analyses include descriptive statistics, harmonic analysis of tidal constituents, spectra and coherence, the principal axis, progressive vector diagrams. These analyses can illustrate the response of residual current to the local wind resulting in the net drift with rotational motion. Current speed ranges from -28 to 33 (cm/sec), with standard deviations from 6.5 to 12.9 (cm/sec). The harmonic analyses of the tidal current show the average form number, 0.12 with semi-diurnal type and the rectilinear orientation of the major axis toward northeast. The magnitudes of the semi-major range from 12.7 to 17.7 (cm/sec) for M2 harmonics, while for S2 harmonics, they range from 6.3 to 10.4 (cm/sec), respectively. In the spectral and coherency analysis of residual current and wind, a periodicity of 13.6 (day) is found to be most important in both records and plays an important role in the net drift of residual current. The progressive vector diagrams of residual current and wind show two types of behaviors such as unidirectional drift and rotational motion. It was also found that 3 % rule holds approximately to drive 1 (cm/sec) drift current by 30 (cm/sec) wind speed based on the correlation of the semi-major axis of wind and residual current.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1431-1438
• /
• 2007

This paper presents a refined design model for current railroad design code on concrete structures exposed to marine environment. A time-varying diffusion coefficient(D) as well as surface chloride$(C_S)$ and chloride threshold level$(C_{lim})$ are studied. Averaging value of the D with time over exposed duration were used to refined durability design model to consider time dependent characteristic of D. The values for $C_S$ and $C_{lim}$ for the seashore in Korea revised for realistic durability design. The proposed model was verified by the so-called performance-based durability design, which is widely used in recent durability design code. Results show that the current standard specification underestimates durability performances of concrete structures exposed to marine environment, so that the cover depth design using current durability evaluation in the standard specifications is very much conservative. Thus, it is found that proposed durability design models for the railroad design code for railway concrete structures can be used effectively for service life design of concrete structures in marine environment.