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Jeon, Joonho,Park, Sungwook Elsevier 2018 Applied thermal engineering Vol.131 No.-
<P><B>Abstract</B></P> <P>Biofuels are an alternative to petroleum fuels in transportation. Among various biofuels, biodiesel has been mixed with diesel fuel for use in compression ignition (CI) engines. Many countries legislate that standard diesel fuels contain a certain amount of biodiesel to reduce exhaust emissions. An increase in biodiesel content to a 20% volumetric ratio (B20) requires only minor modification to existing vehicle systems. Since discrepancies in fuel properties between B20 and conventional diesel fuel, much research has been performed on B20 combustion and emissions for the implementation of vehicles. The present study investigated spatial B20 combustion and soot emission processes in an optical CI engine under various injection pressure conditions. Volumetric 20% of soybean biodiesel added to diesel fuel and both blend fuel and conventional diesel fuel were used as test fuels. Apparent combustion and emissions were observed with respect to auto-ignition, brake power, and thermal efficiency. In addition, visualization system permitted a profound analysis of the spatial combustion flame and soot propagation. A two-color photometric method extracted quantitative soot density from the captured combustion images, which allowed to study the soot formation and oxidation processes. Although soot emissions decreased significantly out of the engine, the variations in the soot formation and oxidation processes in the combustion chamber were remarkable. Compared with neat diesel flame B20 fuel produced higher flame temperature over all injection pressure conditions. While B20 flame temperature was increased, soot emission of B20 fuel was exhausted with higher concentrations. Under a low load and high speed condition, B20 emissions revealed different results from those of general bio-blends with high thermal efficiency regardless of the injection pressure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spatial temperature and soot density in the combustion chamber using endoscope. </LI> <LI> Development of flame and soot emissions for 20% vol. biodiesel blend. </LI> <LI> Two-color photometric method evaluated temperature and soot intensity in images. </LI> <LI> Apparent combustion and emissions features in biodiesel blend and diesel fuels. </LI> </UL> </P>
Jeon, Joonho,Lee, Jong Tae,Park, Sungwook American Chemical Society 2016 ENERGY AND FUELS Vol.30 No.8
<P>Selective catalytic reduction (SCR) systems have been widely used in heavy-duty (HD) diesel engines to meet the stringent emission standards for nitrogen oxides. The mobile SCR system has improved the considerable reduction of NOx emission from HD diesel engines. Many investigations have been performed to enhance the catalytic performance and optimize the SCR system within the diesel engines. The purpose of the present study was to investigate the types of nitrogen components (NO, NO2, N2O, and NH3) in the NOx exhaust emissions prior to and after passing through an SCR device. A EURO VI type commercial heavy-duty diesel engine was equipped to an AC dynamometer. World harmonized stationary cycle and transient cycle were introduced to operate the test engine under road conditions. A new quantum cascade laser analyzer was employed to measure the nitrogen emission species in real time. The engine-out NOx emissions were strongly affected by the load conditions of the engine, which also determined the efficiency of SCR conversion. Total conversion rates of up to 96% were achieved for both test modes. Various concentrations of urea were used as a reducing agent in the SCR system. On the basis of the urea concentration, the conversion efficiency and composition of nitrogen oxides varied under the same engine conditions. The fraction of nitrogen compounds in NOx emissions changed during the catalytic processes within the SCR system. The results yielded accurate concentration values for nitrogen compounds in the commercial heavy-duty engine, warning of the possibility of a new greenhouse gas due to converted NOx emissions.</P>
Jeon, Joonho,Kwon, Sang Il,Park, Yong Hee,Oh, Yunjung,Park, Sungwook Elsevier 2014 APPLIED ENERGY Vol.113 No.-
<P><B>Abstract</B></P> <P>The purpose of this study is to investigate the effects of various engine conditions on the combustion, flame temperature and emission characteristics of dimethyl ether (DME) fuel compared with ultra-low sulfur diesel (ULSD) fuel through experimental and numerical analyzes. In order to analyze the temperature distribution, the KIVA-3V code and an optical HSDI diesel engine equipped with a visualization system were employed. The numerical validation was conducted with the experimental results from a DME-fueled compression ignition engine. In addition, measurement of the flame temperature from images captured during the combustion processes was performed using AVL-ThermoVision software.</P> <P>This investigation showed that the combustion pressure and heat release rate attained their peak value at the lowest engine speed condition for DME and ULSD fuels. The characteristics of the flame temperature value and distribution due to the differences in engine speed conditions and fuel properties were clearly revealed. When the engine speed increased, an inhomogeneous and low combustion temperature was observed. Furthermore, the nitrogen oxides (NO<I> <SUB>x</SUB> </I>) emissions, which are related to the combustion temperature, decreased as the engine speed increased.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Experimental and numerical approaches were used for DME combustion. </LI> <LI> DME fuel properties strongly affected temperature distribution. </LI> <LI> The differences of temperature distribution were showed under various conditions. </LI> <LI> DME combustion and emissions characteristics in comparison with ULSD fuel. </LI> </UL> </P>
Effect of Flow Rate on Smoke Control System for Railway Tunnel Fire
Yejin Ha(Yejin Ha),Joonho Jeon(Joonho Jeon) 한국화재소방학회 2023 International Journal of Fire Science and Engineer Vol.37 No.2
Tunnel is a semi-closed structure with a high risk of fire becuse of difficulty of smoke exhaust and restricted evacuation route in fire. No specific guidelines on smoke control systems have been developed for railway tunnels. Therefore, in the railway tunnel design, an average airflow velocity of 2.5 m/s inside a tunnel for the entry and exit of workers has been used as a reference. In this study, a fire simulation conducted to examine whether the average flow velocity can sufficiently apply on smoke control system in railway tunnel design. An 870-m-long railway tunnel with a single track and double track was modeled, and fire scenarios for light rail cars were simulated. It was found that the reference flow velocity showed sufficient smoke control performance, even at a maximum fire source of 60 MW. However, evacuees might be exposed to smoke due to the backlayer formed immediately. Furthermore, the smoke control performance for the reference velocity does not reflect the influence of the tunnel length. It is necessary to conduct a study on standard for appropriate smoke control performance to reduce fire risk in a railway tunnel fire.
Sang Won Jeon,Changsu Han,Joonho Choi,Young-Hoon Ko,Ho-Kyoung Yoon,Yong-Ku Kim 대한정신약물학회 2017 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.15 No.4
Objective: The purpose of this study was to investigate the therapeutic effects of eye movement desensitization and reprocessing (EMDR) on post-traumatic growth (PTG). Methods: This study was conducted using a sample of ten survivors of a large-scale maritime disaster that occurred in the Yellow Sea, South Korea, in April 2014. A total of eight EMDR sessions were administered by a psychiatrist at two-week intervals over a period of five months, starting two or three months after the accident. Post-Traumatic Growth Inventory (PTGI), Stress-Related Growth Scale (SRGS), Clinician-Administered PTSD Scale (CAPS), and Connor-Davidson Resilience Scale (CD-RISC) were measured before treatment, after sessions 4 and 8, and at three months after treatment completion. Results: After three months from treatment completion, significant increases were observed in PTG (PTGI: Z(8)=–2.380, p =0.017; SRGS: Z(8)=–2.380, p =0.017) and resilience (CD-RISC: Z(8)=–2.386, p =0.017). A decrease in post-traumatic stress disorder (PTSD) level was also significant (CAPS: Z(8)=–2.176, p =0.030). The reduction of CAPS scores was correlated with increases of PTGI (rho=0.78, p =0.023) and SRGS (rho=0.79, p =0.020) scores. The changes in CAPS, PTGI, and SRGS scores between time point of end 8-session and three months follow-up was not significant (all p >0.05). Subjects with higher pre-treatment CD-RISC scores showed more significant improvements in PTGI (rho=0.88, p =0.004) and SRGS (rho=0.83, p =0.010) scores after treatment than did those with lower pre-treatment CD-RISC scores. Conclusion: EMDR therapy using standard protocol for trauma processing helped facilitating PTG in disaster survivors. To generalize these findings, further controlled studies comparing with other treatment modalities for PTSD are needed.