• Clean Technology
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• v.25 no.1
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• pp.91-97
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• 2019

Oxidative desulfurization (ODS) has received much attention in recent years because refractory sulfur compounds such as dibenzothiophenes can be oxidized selectively to their corresponding sulfoxides and sulfones, and these products can be removed by extraction and adsorption. In this work, The oxidative desulfurization of marine diesel fuel was performed in a batch reactor with hydrogen peroxide ($H_2O_2$) in the presence of various supported heteropoly acid catalysts. The catalysts were characterized by XRD, XRF, XPS and nitrogen adsorption isotherm techniques. Based on the sulfur removal efficiency of promising silica supported heteropoly acid catalysts, the ranking of catalytic activity was: $30\;H_3PW_{12}/SiO_2$ > $30\;H_3PMo_{12}/SiO_2$ > $30\;H_4SiW_{12}/SiO_2$, which appears to be related with their intrinsic acid strength. The $30\;H_3PW_{12}/SiO_2$ catalyst showed the highest initial sulfur removal efficiency of about 66% under reaction conditions of $30^{\circ}C$, $0.025g\;mL^{-1}$ (cat./oil), 1 h reaction time. However, through the recycle test of the $H_3PW_{12}/SiO_2$ catalyst, significant deactivation was observed, which was attributed to the elution of the active component $H_3PW_{12}$. By introducing cesium cation ($Cs^+$) into the $H_3PW_{12}/SiO_2$ catalyst, the stability of the catalyst was improved with changing the solubility, and the $Cs^+$ ion exchanged catalyst could be recycled for at least five times without severe elution.

• Fire Science and Engineering
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• v.28 no.3
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• pp.43-48
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• 2014

The purpose of this study is to analyze the flame propagation speed, radiation range, diffusion pattern and combustion completion time of a fire by filling a divided space with single combustible substance. It was found that the flame propagation speed was the fastest (0.2 s) for kerosene and the lowest (82.1 s) for alcohol. In the case of paint thinner, it took 19.0 s for the flame to reach its peak at the fastest speed after ignition while in the case of alcohol, it took 138.6 s for the flame to reach its peak at the lowest speed. In the case of the combustion of 200 ml of flammable liquids, the combustion completion time was 79.9 s for paint thinner, which is the shortest, 135 s for gasoline, 170 s for kerosene, 231.4 s for diesel and 337.0 s for alcohol. In addition, when flammable liquids are combusted, the lower part of the flame is governed by laminar flow pattern and the upper part of the flame showed turbulence pattern. In the case of a test performed for bean oil, it could be seen that if the fire source was removed, the flame was automatically extinguished without further combustion and that white smoke was generated due to incomplete combustion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.585-591
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• 2017

Turbocharging is widely used in diesel and gasoline engines as an effective way to reduce fuel consumption. But turbochargers have turbo-lag due to mechanical friction losses. Bearing friction losses are a major cause of mechanical friction losses and are particularly intensified in the lower speed range of the engine. Current turbochargers mostly use oil bearings (two journal bearings and one thrust bearing). In this study, we focus on the bearing friction in the lower speed range. Experimental equipment was made using a drive motor, load cell, magnetic coupling, and oil control system. We measured the friction losses of the turbocharger while considering the influence of the rotation speed, oil temperature, and pressure. The friction power losses increased exponentially when the turbocharger speed increased.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.5
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• pp.542-547
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• 2015

Since the oil price has been significantly jumped for several years, a heavy oil of low quality has been mainly used in the diesel engine of the merchant ship. Thus, a combustion chamber of the engine has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of the combustion chamber has been getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the engine parts such as exhaust valve, piston crown and cylinder head surrounded with combustion chamber are more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these engine parts is very important to prolong their lifetime in a economical point of view. In this study, Inconel 625 filler metal were welded with GTAW method in the cast steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected and base metal zones were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% $H_2SO_4$ solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. Furthermore, the corrosion current density of the weld metal zone revealed the lowest value, having the highest value of hardness. The corrosive products with red color and local corrosion like as a pitting corrosion were considerably observed at the base metal zone, while these morphologies were not wholly observed in the weld metal zone. In particular, the polarization characteristics such as impedance, polarization curve and cyclic voltammogran associated with corrosion resistance property were well in good agreement with each other. Consequently, it is suggested that the mechanical and corrosion characteristics of the piston crown can be predominantly improved by repair welding method using the Inconel 625 electrode.

• Analytical Science and Technology
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• v.16 no.5
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• pp.339-348
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• 2003

Determination of some PAHs in used engine oils have been carried out by extraction of the components into acetonitrile followed by GC/FID and synchronous spectrofluorimetric technique. 7 PAHs, such as acenaphthene (Ace), anthracene (Anth), benzo(a)pyrene (BaP), chrysene (Chry), phenanthrene (Phen), fluoranthene (Ft), and perlyrene (Per) in used engine oil sample were able to determine separately by synchronous spectrofluorimetry. Calibration curves for those components were linear for the concentration range of 0.4~166 ppb PAHs with the corelation factor of 0.9985~0.9999. The peak areas produced by GC/FID split ratio program were used for the calibration curves of the other 8 PAHs. Detection sensitivity of the synchronous spectrofluorimetry seems to be 100 times more sensitive than GC/FID method. The total amount of PAHs in the used engine oil were 5.5 ng/g for LNG (bus), 10.5 ng/g for LPG(taxi), 92.2 ng/g for gasoline-passenger car, and 130 ng/g for diesel trailer, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.409-417
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• 2014

Since the oil price has been significantly jumped for recent some years, the diesel engine of the merchant ship has been mainly used the heavy oil of low quality. Thus, it has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas in a combustion chamber is getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of most parts surrounded with combustion chamber is more serious compared to the other parts of the engine. Therefore, an optimum weldment for these parts is very important to prolong their lifetime in a economical point of view. In this study, four types of filler metals such as Inconel 625, 718, 1.25Cr-0.5Mo and 0.5Mo were welded with SMAW and GTAW methods in the forged steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected zone and base metal were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% H2SO4 solution. The weld metal and base metal exhibited the best and worst corrosion resistance in all cases of filler metals. In particular, the weld metal welded with filler metals of Inconel 718 revealed the best corrosion resistance among the filler metals, and Inconel 625 followed the Inconel 718. Hardness relatively indicated higher value in the weld metal compared to the base metal. Furthermore, Inconel 625 and 718 indicated higher values of hardness compared to 1.25cr-0.5Mo and 0,5Mo filler metals in the weld metal.

• Korean Journal of Breeding Science
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• v.43 no.3
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• pp.172-176
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• 2011

'Suan' is a new $F_1$ hybrid variety of rapeseed (Brassica napus L.) with early maturing and high oleic acid. This hybrid variety was bred by the cross between Mokpo-CGMS (male sterile line) and 8516-B-5-6-5-3 (restore line) for the production of bio-diesel and edible oil in 2006. 'Suan' has green and parted leaf, yellowish flower, and black seed coat. 'Suan' is more tolerant to lodging and stem rot compared to 'Sunmang', check variety. The ripening date of 'Suan' is June 2nd which is 6 days earlier than 'Sunmang'. Yield trials were conducted from 2006 to 2007 and regional adaptation trials were examined at five locations each in 2008 and 2009. The average seed yield of regional adaptation trials was 381 kg/10a that was 4% higher than that of 'Sunmang'. Total oil content of 'Suan' was 44.3%. Oleic acid content was 68.3%, which is 5.2% higher than 'Sunmang' but, erucic acid was not detected. Total glucosinolate content was 2.31 mg/g. Therefore, this variety is recommended as a leading variety at southwestern area including Jeonnam, Jeonbuk and Kyongnam provinces of South Korea.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.39-48
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• 2009

Biodiesel is estimated to be the best recycling energy source as an alternative fuel for transportation vehicles which represents the biggest share of greenhouse effect gas exhausts. Thus, in order to widely expand use of biodiesel and to enhancement its reliability, studies on quality improvement of biodiesel is needed. In this study, we have produced biodiesel(BD100, BD20) through esterification reaction using raw material of waste frying oil and analyzed compatibility with 24 items of quality criteria. As waste frying oil has high contents of unsaturated fatty acid such as Oleic acid, Linoleic acid and Linolenic acid, it is confirmed that there is no problem in using the same as a raw material of biodiesel. The result of analyzing the quality criteria items of biodiesel showed that it satisfied all the quality criteria except the oxidation stability of BD100, which was 2 hours, fatty acid methyl ester of BD20, which was 18.6w% and the filter plugging point, which was $-5^{\circ}C$. We believe that it will contribute to improved utilization of waste resources as alternative energy if studies on technology to improve quality of some items are provided.

• Journal of Preventive Medicine and Public Health
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• v.29 no.4 s.55
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• pp.785-799
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• 1996

We investigated the 1,004 workers who worked in a automobile factory to study the epidemiologic characterists of dermatoses due to cutting oils. Among the workers, 667(66.4%) answered the questionaire. They are belong to 5 departments of the factory-the Engine-Work(258 workers), Gasoline engine Assembly(210), Diesel engine Assembly(96), Power train Work(86), Power train Assembly(17). We measured the oil mist concentration in air of the departments and examined the workers who had dermatologic symptoms. The results were follows; 1) Oil mist concentration ; Of all measured points(52),9 points(17.2%) exeeded $5mg/m^3$- the time-weighed PEL-and one department had a upper confidence limit(95%) higher than $5mg/m^3$. 2) Dermatologists examined 213 workers. 172 of them complained any skin symptoms at that time - itching(32.5%), papule(21.6%), scale(15.7%), vesicle(12.5%) in order. The abnormal skin site found by dermatologist were palm(29.3%), finger & nail(24.6%), forearm(16.2%), back of hand(8.4%) in order. 3) As the result of physical examination, we found that 160 workers had skin diseases. Contact dermatitis was the most common; 69 workers had contact dermatitis alone(43.1%), 11 had contact dermatitis with acne(6.9%), 10 had contact dermatitis with folliculitis(6.3%), 1 had contact dermatitis with acne & folliculitis, and 1 had contact dermatitis with abnormal pigmentation. Others were folliculitis(9 workers, 5.6%), acne(8, 5.0%), folliculitis & acne (2, 1.2%), keratosis(1, 0.6%), abnormal pigmentation (1, 0.6%), and non-specific hand eczema (47, 29.3%). 4) The prevalence of any skin diseases was 34.0 pet 100 in cutting oil users, and 13.3 per 100 in non- users. Especially, the prevalence of contact dermatitis was 23.0 per 100 in cutting oil users and 23.0 per 100 in non-users. 5) We tried patch test(standard serise, oil serise, organic solvents) on 49 patients to differentiate allergic contact dermatitis from irritant contact dermatitis and found 20 were positive. 6) In a multivariate analysis(independant=age, tenure, kinds of cutting oil), the risk of skin diseases was higher in the water-based cutting oil user and both oil user than non-user or neat oil user(odds ratio were 2.16 and 2.78, respectively). And the risk of contact dermatitis was much higher at the same groups(odds ratio were 5.16 and 6.82, respectively).

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.762-767
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• 2009

In this study, the feasibility of using vegetable oil extracted from tropical crop seed as a biodiesel feedstock was investigated by producing biodiesel and analysing the quality parameters as a transport fuel. In order to produce biodiesel efficiently, two step reaction process(pre-treatment and transesterificaion) was required because the tropical crop oil have a high content of free fatty acids. To determine the suitable acid catalyst for the pre-esterification, three kinds of acid catalysts were tested and sulfuric acid was identified as the best catalyst. After constructing the experimental matrix based on RSM and analysing the statistical data, the optimal pre-treatment conditions were determined to be 26.7% of methanol and 0.982% of sulfuric acid. Trans-esterification experiments of the pre-esterified oil based on RSM were carried out, then discovered 1.24% of KOH catalyst and 22.76% of methanol as the optimal trans-esterification conditions. However, the quantity of KOH was higher than the previously established KOH concentration of our team. So, we carried out supplemental experiment to determine the quantity of catalyst and methanol. As a result, the optimal transesterification conditions were determined to be 0.8% of KOH and 16.13% of methanol. After trans-esterification of tropical crop oil, the produced biodiesel could meet the major quality standard specifications; 100.8% of FAME, 0.45 mgKOH/g of acid value, 0.00% of water, 0.04% of total glycerol, $4.041mm^2/s$ of kinematic viscosity(at $40^{\circ}C$).