• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.425-430
• /
• 2008

To verify the system performance of portable AE leak diagnosis system which can measure with moving conditions, AE activities such as RMS voltage level, AE signal trend, leak rate degree according to AE database, FFT spectrum were measured during operation on total 11 valves of the secondary system in nuclear power plant. AE activities were recorded and analyzed from various operating conditions including different temperature, type of valve, pressure difference, valve size and fluid. The results of this field study are utilized to select the type of sensors, the frequency band for filtering and thereby to improve the signal-to-noise ratio for diagnosis for diagnosis or monitoring of valves in operation. As the final result of application study above, portable type leak diagnosis system by AE was developed. The outcome of the study can be definitely applied as a means of the diagnosis or monitoring system for energy saving and prevention of accident for power plant valve. The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18 ". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.

• Journal of the Korean Society of Combustion
• /
• v.14 no.1
• /
• pp.31-38
• /
• 2009

The effects of acoustic excitation of coaxial air on mixing enhancement and reduction of nitrogen oxides (NOx) emission were investigated. A compression driver was attached to the coaxial air supply tube to impose excitation. Measurements of NOx emission with frequency sweeping were performed to observe the trend of NOx emission according to the fuel and air flow conditions and to inquire about the effective excitation frequency for reducing NOx. Then, Schlieren photographs were taken to visualize the flow field and to study the effect of excitation. In addition, phase-locked particle image velocimetry (PIV) was performed to acquire velocity field for each case and to investigate the effect of vortices more clearly. Direct photographs and OH chemiluminescence photographs were taken to study the variation of flame length and reaction zone. It was found that acoustic forcing frequencies close to the resonance frequencies of coaxial air supply tube could reduce NOx emission. This NOx reduction was influenced by mixing enhancement due to large-scale vortices formed by fluctuation of coaxial air jet velocity.

• Journal of the Korean Institute of Educational Facilities
• /
• v.14 no.1
• /
• pp.58-65
• /
• 2007

For the moderns who spend more than 80% of the time inside a building, interior environment became important since it directly affects their health. Recently as noxiousness of the air contaminants of the interior space stood out as well as the above trend, the Ministry of Environment enacted a lawto maintain the interior air quality at certain level of standard in the multi use facility and newly constructed apartment. To make the indoor air clean, removal technology of various contaminants should be developed and interior materials with chemical treatment should be restrained. In other words, selection of interior finish affects indoor air quality from the initial design stage to the construction stage. However, only limited contaminants emission data of building materials are supplied by related companies. There is no average contaminants emission data for overall materials. Moreover, high cost and equipments for one time measurement of VOCs emission of interior finish are the obstacles of active research and data measurement. Therefore, this paper searched the current condition of average VOCs & HCHO emission of various interior finish based on the study requested to research center from the building material company through Stands Test Method for Indoor Air Quality.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.213-219
• /
• 2003

Acoustic emission behavior during fatigue crack growth test was investigated under various loading condition. To describe the acoustic emission activity, counts rate (d/dn) was related with SIFR (stress intensity factor range, K). Results indicated that SIFR could be divided into two parts according to its relationship with counts rate. For $K<25_{MPa\sqrt{m}}$, counts rate was increased as the SIFR increased. However, for values greater than $25_{MPa\sqrt{m}}$ , decreasing behavior was shown. This behavior of counts rate corresponding SIFR was keeping the same trend regardless of load range or crack length. Acoustic emission response to the single overload was sudden drop and slow recovery in counts rate like crack growth retardation. Under variable loading condition, counts rate of each loading block was same as that of constant amplitude loading. Overall experimental data was somewhat scattered since sensitive characteristics of acoustic emission method. However, these empirical relations indicated that counts rate was uniquely correlate with single parameter, SIFR.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.8
• /
• pp.9-15
• /
• 1999

Die-sinking electrical discharge machining(EDM) for conductive ceramic matrix composite(CMC) of Tic/$Al_2O_3$ was experienced with addition of ultrasonic emission, and the results were compared with ones obtained by the EDM only. From this experimental study, the values of material removal rate(MRR) and surface roughness($R_{max}$), scanning electron microscope(SEM) micrographs, and weibull probability distribution of bending strength for the specimens were obtained and compared. The trend of MRR was found to be increased slightly with the current and the duty factor for both EDM only and EDM with ultrasonic emission. The MRR values were found to be increased for EDM with ultrasonic emission. The SEM micrographs of EDMed surface by under various operating conditions showed less micro cracks in various places. Although smaller bending strength value was obtained by EDMed surface with ultrasonic emission by weibull probability distribution analysis of bending strength.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.1
• /
• pp.73-81
• /
• 2011

The performance of emission factor has been validated by comparison with on-road test data. Emission factor, which is a function of vehicle speed, has been acquired based on chassis dynamometer test with NIER driving pattern. Portable Emission Measurement System, PEMS has measured on-road emission. Test vehicle was operated on defined test routes under different driving conditions, and made ten trips along its route. Emission factors properly simulate on-road test result, although there is some drawback to consider variety of driving condition on real world. Vehicle specific power and acceleration have been used to explain the distributed on-road result within same vehicle speed range. The trend in carbon dioxide and nitrogen oxide emission with respect to specific power and acceleration is clear. It has been found that specific power is a good explanatory variable for microscopic analysis for modal test result. Acceleration is good for microscopic as well as macroscopic analysis.

• Korean Journal of Soil Science and Fertilizer
• /
• v.49 no.6
• /
• pp.826-831
• /
• 2016

he land use, land-use change, and forestry (LULUCF) is one of the greenhouse gas inventory sectors that cover emission and removals of greenhouse gases resulting from land use such as agricultural activities and land use change. Particularly, LULUCF-Cropland sector consists of carbon stock changes in soil, $N_2O$ emissions from disturbance associated with land use conversion to cropland, and $CO_2$ emission from agricultural lime application. In this paper, we conducted the study to calculate the greenhouse gases emission of LULUCF-Cropland sector in South Korea from 1990 to 2014. The emission by carbon stock changes, conversion to cropland and lime application in 2014 was 4424, 32, and 125 Gg $CO_2$-eq, respectively. Total emission from the LULUCF-Cropland sector in 2014 was 4,582 Gg $CO_2$-eq, increased by 508% since 1990 and decreased by 0.7% compared to the previous year. Total emission from this sector showed that the largest sink was the soil carbon and its increase trend in total emission in recent years was largely due to loss of cropland area.

• Journal of the Korean association of regional geographers
• /
• v.11 no.6
• /
• pp.559-570
• /
• 2005

The purpose of this paper is to estimate the effect of population change on waste emission in the case of Busan City. The results are as follows : First, population and waste emission in Busan City Show decreasing pattern since 1995. According to increase or decrease of population and waste emission, The 16 Gus in Busan City are categorited into 5 types. Comparing the difference of population and waste emission between 1995 and 2003, we find out a similar trend by 16 Gus in Busan City. Second, the waste emission shows the positive relation with the number of population and the land by use. But there exists multicollinearity between population and the land by use, and the population is considered the main factor of waste emission. Third, the population causes 92% or more of the waste emission in Busan City, and future researches are required for the additional causes of waste generation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.529-533
• /
• 2008

Recently in Korea, noise is one of the most important social issues because the living standard becomes more higher. Railway noise is also annoying one in our society, although railway has very positive role in our country. The major measures for mitigation of railway noise in Korea are rail welding and installation of noise barrier on the noisy area. But these measures have its own limit for the calm and comfortable living environment. In Europe the railway noise problem has been treated more systematically and aggressively, there has been emission noise standard for Trans-European rail network. In this paper, the trend of noise standard for railway vehicles will be reported and the check point for our country will be discussed.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2005.11a
• /
• pp.85-86
• /
• 2005