• 한국자동차공학회논문집
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• 제10권5호
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• pp.9-14
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• 2002

The durability prediction of emission control components, especially 02 sensor and catalytic converter, is getting more important as emission regulation is getting stricter and vehicle durability mileage requirement is also extended from 80,000 ㎞ to 160,000 km in Korean market. And the duration of vehicle mileage accumulation to get vehicle exhaust emission deterioration factor for certification is required to be shorter in order to reduce the vehicle development time. Since most of the vehicle emission development tests are done on chassis dynamometer and aging bench by using vehicle aging modes, real road condition and in-use driving patterns must be reflected into them to predict the vehicle emission level and to meet emission regulation especially at high mileage. In order to get the frequent driving pattern of vehicle and the aging characteristic of emission components, a vehicle was tested by changing drivers and driving roads around Seoul. Real road driving patterns were analyzed and compared with those of the certification modes which are well known in automotive industry.

• 한국기후변화학회지
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• 제5권3호
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• pp.219-230
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• 2014

In this study, greenhouse gas emission of magnesium industry was estimated and the reduction potential of the greenhouse gas emission was evaluated with reduction technologies. Default value of IPCC guideline was used to calculate the greenhouse gas emission and $SF_6$ alternatives were considered in reduction potential. Import of magnesium ingot was 22,806 ton in 2013, which will be expected to increase to 81,700 ton with 20% rate in 2020. Magnesium ingot was consumed to produce magnesium alloy in diecasting process. Recently, commercial production of crown magnesium and magensium plate began. Based on ingot consumption, $CO_2$ emission of domestic magnesium industry was estimated to 504,000 ton, which is about 0.79% of domestic industrial emissions. Reduction potential of diecasting process was estimated to 489,320 ton by changing SF6 to alternative gases such as HFC-134a, Novec-612. Emission factor of Tier 3 level should be developed to enhance the accuracy of greeenhouse gas emission of magnesium industry.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.249-252
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• 2006

When concrete is subjected to uniaxial compression, the failure process is normally initialed from a localized zone. The localization of failure governs structural behaviors of concrete. In this paper, the compressive strength and failure behavior of recycled coarse aggregate concrete with different replacement level of recycled coarse aggregates are investigated using acoustic emission(AE). AE characteristics of concrete were investigated during the entire loading period. For these purpose, four recycled coarse aggregate replacement level (i.e 0%, 30%, 60% and 100%) were considered in this paper. Result from this study show AE signal, AE method can apply to investigate a compressive failure mode according to recycled coarse replacement level.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.38-45
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• 2001

Environmental protection on the ocean has been interested and nowadays the International maritime organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the emission characteristics of 4 stroke propulsion diesel engine in E2 cycle (constant speed) and E3 cycle (propeller curved speed). Also the effects of important operating parameters in terms of intake air pressure and temperature, and maximum combustion pressure are described on the specific emissions. Emissions measurement and calculation are processed according to IMO technical code. The results show that NOx emission level in E3 cycle is higher than E2 cycle due to lower engine speed and lower maximum combustion pressure by retarding fuel injection timing. Intake air temperature has strong influence on NOx emission production. And CO, HC emissions are not affected by maximum combustion pressure and intake air pressure and temperature.

• International Journal of Automotive Technology
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• 제2권4호
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• pp.123-133
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• 2001

An important goal in diesel engine research is the development of a means to reduce the emission of oxides of nitrogen ($NO_x$) and soot particulate. A phenomenological model based on the multizone concept is used in the current paper to analyze and compare the effects of exhaust gas recirculation (EGR) and split fuel injection on emission from a compression-ignited, direct-injection engine. The present results show that $NO_x$ can be reduced with a minimum penalty of soot particle emission with cooled EGR. Compared with EGR, split fuel injection has a higher soot penalty at a given level of $NO_x$ reduction.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.23-29
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• 2001

This paper is the second of companion papers, which investigate port-masking effects on emission and fuel economy. Port-masking was applied to commercial SOHC 3-valve engine by inserting masking plates between manifold and port. To induce various conditions of stratification, six types of masking plates were applied. In this paper, main interest is focused on the influence of injection timing on emission and fuel economy. Various injection timing was applied to the six cases, under the stoichiometric and lean-limit air-fuel ratio. Under the stoichiometric condition, an explanation about the reason of the change in emission level due to injection timing change is given. It is observed that NOx emission under the LML condition varies significantly when the injection timing changes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 추계학술대회 논문집
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• pp.95-100
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• 1991

From a manufacturing standpoint it would be desirable to monitor the degradation of drawing die, that is essential for the maintenance of quality, the evaluation of product integrity and the reducing scrap. Acoustic emission is powerful method in monitoring fine wire drawing process, especially in detecting the die fracture at early stage. Experiments at so suggested that acoustic emission signals contained valuable information regarding the stage of a drawing process such as the surface appearance of products and the condition of lubrication. Using these informations makes AE monitoring techniques a possible tool in monitoring the drawing process operation. In order to approach this, this paper discusses the nature of acoustic emission signals produced in drawing process under various conditions. Experimental results are presented which illustrate the effects of wire and die material, lubricants, and drawing speed on the generation and the mean voltage level of acoustic emission signals. The results from these tests give controlling factors of acoustic emission generation.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.172-179
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• 2001

Experimental studies have been carried out to find out the characteristics of the heat transfer, combustion emission and noise in the boilers without any extra firing zone for complete combustion of fuel. For the experiments a burner of premixed type and some heat exchangers were designed and manufactured. Also test facilities including a data acquisition system and various measuring devices were set up in order to measure automatically the various temperatures and flow rates of water and combustion gas. Various experiments were performed to find out the heat transfer characteristics as well as combustion emission and noise. In general, the burner which has uniform holes in the burner nozzle plate generates big combustion noise . whistling. The noise reduction method is discussed in this study. Many experimental data such as noise level, the amount of pollutant emission and heat transfer rate for different combination of heat exchangers are given as comparison bases for numerical studies.

• 천문학회지
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• 제40권4호
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• pp.113-118
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• 2007

Recently far infra-red (FIR) polarization of the $850{\mu}m$ continuum emission from T Tauri disks has been detected. The observed degree of polarization is around 3 %. Since thermal emission from dust grains dominates the spectral energy distribution at the FIR regime, dust grains might be the cause of the polarization. We explore alignment of dust grains by radiative torque in T Tauri disks and provide predictions for polarized emission for disks viewed at different wavelengths and viewing angles. In the presence of magnetic field, these aligned grains produce polarized emission in infrared wavelengths. When we take a Mathis-Rumpl-Nordsieck-type distribution with maximum grain size of $500-1000{\mu}m$, the degree of polarization is around 2-3 % level at wavelengths larger than ${\sim}100{\mu}m$. Our study indicates that multifrequency infrared polarimetric studies of protostellar disks can provide good insights into the details of their magnetic structure.

• 천문학논총
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• 제30권2호
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• pp.531-533
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• 2015

We have investigated the long term variability of the intensities of the broad-line region emission lines in the UV spectra of Seyfert I galaxy NGC 5548 from 1973-1996. We have obtained the following results: 1) a high level correlation between the intensities of emission lines as well as between intensities of emission lines and continuum fluxes was discovered. With increasing wavelength the correlation in both cases becomes weaker, 2) the relationship between the intensity of emission lines and the flux radiation in the continuum can be expressed by a power law function with coefficients of ${\alpha}{\approx}0.8-1.1$ for different lines. When the difference between the wavelengths of spectral lines and the continuum is increased, the value of the power function decreases, and 3) it was found that the magnitude of the variability of the line intensities are weaker than the range of variability of the continuum fluxes. The magnitude of the variability of the line intensities and the continuum fluxes increase at longer wavelengths.