• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.452-459
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• 1997

For computer aided design and construction of low noisy power plants, indoor and outdoor noise prediction program has been developed. The program utilizes the predefined data of noise sources and building materials and has the faculty to estimate the source level using the empirical formula in case of the measured data not being available. In the noise prediction, the mutual noise propagation between indoor and outdoor sites are considered. The outdoor noise source in the calculation of geometric divergence effects is modelled as the omni-directional finite line or planar source according to the source geometry and the receiving points. Outdoor noise prediction is carried out to consider the diffraction effect due to plant structures as well as the attenuation effect due to atmospheric absorption and soft ground. The results of indoor and outdoor noise prediction for a recently constructed diesel engine power plant show good agreement with the measured.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.402-405
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• 2006

The diffuser noise of HVAC(heating ventilating and air-conditioning) uses dB(A) or NC as a indoor noise criteria that ASHRAE represents, and there is no specific guide line for application. According to the previous study, there are some problems like that even though the sound level of sound source is same, the NC shows different values, which makes the noise rating confused. This problem is caused by the frequency characteristics of sound source and its sound level. Therefore, appropriate evaluation method should be considered based on the subjective responses. This study aims to analyze the physical parameters appropriate for the evaluation of HVAC diffuser noise. To achieve this, recording of sound sources, calculation of physical parameters and psycho-acoustic experiment were carried out and the results were derived from the correlation analysis between physical parameters and subjective evaluatio

• Journal of Biosystems Engineering
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• v.42 no.3
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• pp.170-189
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• 2017

Purpose: This paper presents Raman chemical imaging technology for inspecting food and agricultural products. Methods The paper puts emphasis on introducing and demonstrating Raman imaging techniques for practical uses in food analysis. Results & Conclusions: The main topics include Raman scattering principles, Raman spectroscopy measurement techniques (e.g., backscattering Raman spectroscopy, transmission Raman spectroscopy, and spatially offset Raman spectroscopy), Raman image acquisition methods (i.e., point-scan, line-scan, and area-scan methods), Raman imaging instruments (e.g., excitation sources, wavelength separation devices, detectors, imaging systems, and calibration methods), and Raman image processing and analysis techniques (e.g., fluorescence correction, mixture analysis, target identification, spatial mapping, and quantitative analysis). Raman chemical imaging applications for food safety and quality evaluation are also reviewed.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.107.1-107.1
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• 2011

Density Probability Distribution Functions (PDFs) are a classic statistical way to study properties of Interstellar Medium (ISM) turbulence. In our three-dimensional MHD simulations, density PDFs of the position-position velocity (PPV) spaces are close to a log-normal distribution. the PDF widths depend on the plasma parameters such as magnetic strength and sonic Mach number. Futhermore, we compare these simulations results to Galactic molecular clouds observed by Jackson et. al (2006). By fitting of the velocity dispersion in the spectral line observation, volume density PDFs of the defined molecular clouds indicate that the sound speeds of the turbulences seem to have a few times larger than the simulation results. In order to understand the inconsistency with general characteristics of turbulence, we consider other simulations inducing the turbulent flow randomly at small driving scales. We find that the density PDF width decreases at more smaller driving scale. Finally, the simulations suggest that sources of ISM turbulence in Galactic molecular clouds can be important on small scales.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.72.2-72.2
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• 2011

We have performed the first self-consistent, large-scale simulation of cosmic reionization by stellar sources, including the Population III stars that emerged and were hosted by minihalos at very high redshifts (z~40). Based on this result, we calculate the redshifted radiation background from these stars and the relic H II regions which can be observed at near-infrared and infrared regime. Formation of the first stars inside minihalos are quenched by radiative feedback at z~15, while the relic H II regions have much longer lifetime due to the slow recombination rate. Therefore, the radiation output from the relic H II regions, dominated by Lyman alpha photons, will be observed both in the near-infrared and infrared regime. The estimated background from the first stars inside minihalos are still sub-dominant compared to that from stars inside larger halos, however, and thus complementary observations are necessary, such as redshifted 21-cm line observation.

• Journal of the Optical Society of Korea
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• v.10 no.4
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• pp.157-161
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• 2006

A synchrotron light source is useful in the vacuum ultraviolet (VUV) regime for olecular spectroscopy, such as photo absorption, photoionization, and dissociative hotoionization. In this research, we used a double-ion chamber (DIC) to measure hotoabsorption cross sections of a NO molecule in the wavelength range from 90 to 135 nm of 3B1 beam-line of the Pohang synchrotron light source with the resolution of the onochromator being 0.06 nm. The appearance wavelength for ionization was measured to be $134.19{\pm}0.09nm$ that is placed in the middle of the reported values though they don't agree with each other within the relative error limits. The auxiliary experimental works ave been done to test if there are any systematic error sources. The resultant ross-sections agree with previous results in general.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.220-221
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• 2003

Intracavity second harmonic generation of diode pumped solid state lasers in the visible and ultraviolet regions provide efficient, compact and robust light sources for various applications, such as optical data storage, material processing, spectroscopy and bioanalysis. Advantages of neodymium vanadate (Nd：$YVO_4$) as a gain medium for intracavity-doubled lasers over Nd：YAG lie in the facts that the gain spectrum consists of a single line with short absorption depth, and that the stimulated emission cross sections are larger. (omitted)

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.185-191
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• 1999

This paper deals with a method to predict the noise level inside metro electric cars running a single-line tunnel at the speed of 80km per hour using ray tracing method, a kind of ray acoustics generally used for a high-frequency and air-born noise analysis. The interior of the car including a under-frame, seats, side doors, end doors, door-pockets, side panels, end panel, a roof panel and so on is modeled. And in order to describe the noise power coming inside, artificial noise sources are designated using sound transmission loss data of each section measured from simple tests and external noise level. The noise level inside the car is calculated and its properties are investigated. The results satisfy the criteria on noise level inside the car.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1371-1373
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• 2008

Recently, the reduction of greenhouse gas (GHG) is the most important international issue. In order to control efficiently GHG emissions and reduction, it is essential to establish GHG inventory preferentially. The aim of this study was to establish the GHG inventory of Korean railroad. The GHG sources were divided into direct and indirect emissions. The GHG released from the operation of rolling stocks was classified according to operating line and the kind of car. Finally, the GHG emission of Korean railroad can be managed systematically using this GHG inventory.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.1
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• pp.11-39
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• 2018

Tritium and $^{14}C$ are two most important radionuclides released from nuclear facilities to the environment, and $^{14}C$ contributes dominant radiation dose to the population around nuclear power plants. This paper presents an overview of the production, pathway, species and levels of tritium and $^{14}C$ in nuclear facilities, mainly nuclear power plants. The methods for sampling and collection of different species of tritium and $^{14}C$ in the discharge gas from the stack in the nuclear facilities, atmosphere of the nuclear facilities and environment are presented, and the features of different methods are reviewed. The on-line monitoring methods of gaseous tritium and $^{14}C$ in air and laboratory measurement methods for sensitive determination of tritium and $^{14}C$ in collected samples, water and environmental solid samples are also discussed in detailed. Meanwhile, the challenges in the determination and speciation analysis of tritium and $^{14}C$ are also highlighted.