• Journal of Wetlands Research
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• v.15 no.2
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• pp.165-170
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• 2013

Pilot scale study was carried out to produce Volatile Fatty Acids with primary sludge from municipal wastewater treatment plant. An acid fermenter was operated at pH 9, $35^{\circ}C$, SRT of 3.5-4.25d, using a final effluent as elutriating water(Mode-I) and pH 9, SRT 5d, temperature of $35^{\circ}C$(Mode-II), $55^{\circ}C$(Mode-III), using a primarily treated water as elutriating water. Although solubilization rate was enhanced with the increase of temperature, the VFAs production rate was decreased. The VS reduction was shown approximately 56%, and the sludge volume reduction was 93%. The optimal conditions for solubilization was obtained at pH 9, $35^{\circ}C$ and SRT of 5d.

• The Journal of the Petrological Society of Korea
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• v.11 no.3_4
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• pp.121-137
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• 2002

Metamorphic evolution of the Ogcheon metamorphic belt has been studied by many investigators for the past few decades. P-T conditions of the Ogcheon metamorphic belt were estimated as 4.2-9.4 kbar and $490-630^{\circ}C$, corresponding to the medium-pressure type. In addition, the clockwise P-T-t path suggests a crustal-thickening event in association with the formation of thrust nappes. However, some details on deformation and orogeny of the Ogcheon metamorphic belt have been ambiguous yet. Although the metamorphic age has been also equivocal, recent isotopic studies strongly suggest that the peak metamorphism in the Ogcheon metamorphic belt has occurred at ca. 300-280 Ma between Late Carboniferous and Early Permian. It is thus inferred that the Ogcheon metamorphic belt and the Taebaegsan basin have evolved as separate terranes and that both were sutured at ca. 250-220 Ma. These results are partly in contrast with those of previous workers and require a revised framework for tectonic evolution of the Ogcheon belt. In addition, it is likely that the Ogcheon belt is correlative with the Hida marginal belt and the Hida metamorphic belt.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.118-127
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• 2007

This study investigated the effect of varying TS concentration levels using supernatant of food waste. The experiment was performed at varying TS concentration levels ranging from 5% to 10% by a $35^{\circ}C$-mesophilic digestion reactor, dual digestion system with acid and methane fermenters combined. As a result, removal efficiency and stabilization were observed at TS concentration of 7~8%, But the removal efficiency notably decreased at 8% or higher TS level. At a stabilized phase of the reactor, more than $0.3m^3/kg{\cdot}vs$ gas was produced, with phenomena such as salt accumulation and increase of pH level being unnoticed. These results indicate that the increase of anaerobic digestion of food waste supernatant TS content has an effect on reaction and that it is necessary to control and operate concentration within 8%, given that the effect is stronger at 8% or higher.

• International Journal of Highway Engineering
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• v.14 no.4
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• pp.9-18
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• 2012

PURPOSES : This study evaluated the field applicability and laboratory performance of warm-mix asphalt (WMA) as an alternative technology in asphalt pavement. METHODS : The pilot road using two different types of WMA mixture and one HMA mixture was constructed in Waegwan-Seokjeok road construction site and the mixtures were sampled at the asphalt plant for laboratory testings. The field applicability was assessed in environmental aspects, such as $CO_2$ emission, and in aspects of constructibility using the existing equipment and procedure, i.e., thickness and density measurement. The laboratory testings included the moisture susceptibility test by AASHTO T283, dynamic modulus test, triaxial repeated load permanent deformation test, and the fatigue test. RESULTS : The temperatures for production and compaction of WMA were $20{\sim}30^{\circ}C$ lower than those for HMA and therefore, the noxious gas emission were significantly reduced. The field density of WMA pavements was similar or better than that of HMA pavement. From the laboratory testings, it was found that WMA mixtures exhibit comparable performance to HMA mixture in moisture susceptibility, permanent deformation, and fatigue performance. CONCLUSIONS : With these results, it would be concluded that WMA could replace the existing HMA technology without any significant issue. To support this conclusion, it is necessary to track the long-term performance of WMA in pilot road.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.414-420
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• 2006

Effluent from an anaerobic digestion system with an elutriated phased treatment(ADEPT, Anaeorbic Digestion Elutriated Phase Treatment) for piggery waste treatment using anaerobic ammonium oxidation(ANAMMOX) process was used as a substrate of partial nitrification reactor. In mesophilic condition($35^{\circ}C$), controlling parameters of nitrite accumulation were HRT, pH, free ammonia(FA) and hydroxylamine rather than dissolved oxygen. Bicarbonate alkalinity consumption ratio including bicarbonate stripping and buffering was 8.78 g $Alk._{comsumed}/g\;NH_4-N_{converted}$. In steady state for 1 day of HRT and $2.7{\sim}4.4mg/L$ of DO, $NO_2-N/NH_4-N$ ratio of partial nitrification effluent was about $1{\sim}3$, which was applicable to ANAMMOX reactor influent for the combined partial nitrification-ANAMMOX process.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.1
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• pp.83-95
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• 2020

The economic issue of the period of return versus investment has emerged to efficiently utilize the thermal energy of public resource recovery facilities using waste and private thermal source facilities using BIO-SRF. Accordingly, the optimum temperature and pressure facilities are required beyond the traditional designed, constructed and operated. In this study, we analyzed current energy output by different heat and pressure model in domestic facilities, and calculated the characteristics of green-house gas emission. In order to, utilize the thermal energy producing facilities using waste and biomass fuel more efficiently, it is temperature and pressure, which will lead to more lucrative investment and return as well.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.31-37
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• 2015

PURPOSES : To design a pre-heater for warm in-place recycling equipment, three different heating systems were evaluated to determine their thermal efficiency. METHODS: In this study, a $30cm{\times}30cm{\times}15cm$ wheel-tracking specimen was used to measure the inner temperature as a function of the heating system. The inner temperature of the specimen was measured with a data logger at the surface, and at depths of 1cm, 2cm, 3cm, 4cm, and 5cm. To evaluate the thermal efficiency, the researchers used three different types of equipment, namely, IR, a heating wire, and a gas burner. RESULTS: The IR heating system exhibits a higher level of performance than the others to achieve the target temperature at a depth of 5cm in the specimen. The gas burner system was capable of heating the surface to a temperature of up to $600^{\circ}C$. The other types, however, cannot heat the surface up to 600. The thermal efficiencies were measured based on the laboratory conditions. CONCLUSIONS: To find the most effective system for application to the development of a pre-heater for warm in-place recycling, various systems (IR, heating wire, gas burner) were examined in the laboratory. As a result, it was found that the hot plate of a gas burner system provides the highest temperature at the surface of the asphalt but, of all the systems, the IR system provides the best internal temperature increase rate. Furthermore, a gas burner can age the asphalt binder of the surface layer as a result of the high temperature. However, the gas burner cannot attain the target temperature at 5cm. The IR system, on the other hand, is effective at increasing the internal temperature of asphalt.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.19-24
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• 2015

Joint properties of electric control unit (ECU) module using Sn-Cu-(X)Al(Si) lead-free solder alloy were investigated for automotive electronics module. In this study, Sn-0.5Cu-0.01Al(Si) and Sn-0.5Cu-0.03Al(Si) (wt.%) lead-free alloys were fabricated as bar type by doped various weight percentages (0.01 and 0.03 wt.%) of Al(Si) alloy to Sn-0.5Cu. After fabrications of lead-free alloys, the ball-type solder alloys with a diameter of 450 um were made by rolling and punching. The melting temperatures of 0.01Al(Si) and 0.03Al(Si) were 230.2 and $230.8^{\circ}C$, respectively. To evaluation of properties of solder joint, test printed circuit board (PCB) finished with organic solderability perseveration (OSP) on Cu pad. The ball-type solders were attached to test PCB with flux and reflowed for formation of solder joint. The maximum temperature of reflow was $260^{\circ}C$ for 50s above melting temperature. And then, we measured spreadability and shear strength of two Al(Si) solder materials compared to Sn-0.7Cu solder material used in industry. And also, microstructures in solder and intermetallic compounds (IMCs) were observed. Moreover, thickness and grain size of $Cu_6Sn_5$ IMC were measured and then compared with Sn-0.7Cu. With increasing the amounts of Al(Si), the $Cu_6Sn_5$ thickness was decreased. These results show the addition of Al(Si) could suppress IMC growth and improve the reliability of solder joint.

• Korean Journal of Optics and Photonics
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• v.21 no.4
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• pp.133-138
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• 2010

All radiation thermometers have a size-of-source effect (SSE) and a self-radiation effect (SRE). The SSE,defined as dependence of the detector signal of a radiation thermometer on the diameter of a source, is critically dependent on the wavelength since diffraction is the main cause. In this paper, we have measured the SSE and the SRE of TRT2 (Transfer Radiation Thermometer 2, HEITRONICS) widely used as a transfer standard in low and middle temperature range. At $300^{\circ}C$, The radiation temperature difference between the 60 mm diameter blackbody and 10 mm diameter blackbody due to the SSE was estimated to be $3.5^{\circ}C$ in low temperature mode ($8-14\;{\mu}m$) and $0.5^{\circ}C$ in middle temperature mode ($3.9\;{\mu}m$). In addition, the measured radiation temperature difference of the blackbody due to the SRE was found to be 110 mK when the body temperature change of TRT2 was set at $2.6^{\circ}C$.

• Food Science and Preservation
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• v.10 no.1
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• pp.70-74
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• 2003

The distribution of mesophilic and thermophilic bacteria in milled rice was not different according to growing land and variety of rice. However, The number of these bacteria were abundant in milled rice of lower milling degree or longer storage period. The growth of thermophilic bacteria in cooked rice of electric rice cooker was rapidly increased during storage of lower temperature below 75 $^{\circ}C$. Thermophilic bacteria were not appeared just after cooking. After cooked rice was stored far 18∼24 hon thermophilic bacterial growth was rapidly increased by changing spore to vegetative cell. The positive relation between cell number of thermophilic bacteria and occurrence of off-odor was slightly observed. The number of thermophilic bacteria in upper cooked rice of oven and was higher than those in inner and lower cooked rice. Major volatile compound of milled rice cooked and stored in electric rice cooker was hexanal oriented from rice. After long storage, it was confirmed that furan was major volatile compound as off-odor.