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IMPROVEMENT OF NOX REDUCTION RATE OF UREA SCR SYSTEM APPLIED FOR AN NON-ROAD DIESEL ENGINE
Joonsoo Han,Taemin Kim,Haksup Jung,Sukang Pyo,조규백,Youngtaig Oh,김홍석 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.6
Urea SCR technology has been widely used to reduce NOx emissions of diesel engines. Despite remarkable development for decades, more advanced control and optimization of urea SCR systems are still required as global NOx emissions standards are expected to become more stringent. This study investigated several influential parameters of urea SCR system to improve NOx reduction efficiency. This study uses a commercialized UWS (Urea Water Solution) supply system and a SCR catalyst which was installed in the exhaust line of a non-road CRDI (Common Rail Direct Injection) diesel engine. From this study, it was found that the low space velocity of SCR catalyst is essential for high NOx reduction efficiency, especially at low temperatures. Early injection of UWS enhances the overall NOx reduction efficiency if UWS injection was carefully controlled to avoid urea deposits. Rich injection of UWS with AOC is a good strategy for high NOx reduction efficiency. However, NOx reproduction in the AOC, which has an adverse effect on the overall NOx reduction rate, occurs at high exhaust gas temperatures. System insulation also can improve the NOx reduction efficiency by a few percentage points.
Off-road용 디젤엔진에서의 VGT 및 EGR 적용에 따른 엔진 배기 및 연비 특성 평가
하형수(Hyeongsoo Ha),신재식(Jaesik Shin),정학섭(Haksup Jung),표수강(Sukang Pyo),강정호(Jungho Kang) 한국연소학회 2016 한국연소학회지 Vol.21 No.2
To meet the Tier-4 emission standard, a variety of combustion technology in the field of off-road engine has been applied in conjunction with the engine after treatment technology. In this study, as the basis study for applying VGT and HPL EGR to 3.6 L CRDi engine, exhaust gas characteristics and fuel economy characteristics are confirmed in accordance with VGT and EGR operating conditions. Consequently, in the EGR applicable conditions, 60% VGT vane duty condition was confirmed that the trade-off characteristics between NOx and smoke are advantageous. In addition, in view of BSFC, VGT vane duty is considered desirable to control at around 50%.
Cho, Myung Soo,Kim, Sang Jin,Ku, Seung-Yup,Park, Jung Hyun,Lee, Haksup,Yoo, Dae Hoon,Park, Un Chul,Song, Seul Ae,Choi, Young Min,Yu, Hyeong Gon Elsevier 2012 Stem cell research Vol.9 No.2
<P>Dysfunction and loss of retinal pigment epithelium (RPE) are major pathologic changes observed in various retinal degenerative diseases such as aged-related macular degeneration. RPE generated from human pluripotent stem cells can be a good candidate for RPE replacement therapy. Here, we show the differentiation of human embryonic stem cells (hESCs) toward RPE with the generation of spherical neural masses (SNMs), which are pure masses of hESCs-derived neural precursors. During the early passaging of SNMs, cystic structures arising from opened neural tube-like structures showed pigmented epithelial morphology. These pigmented cells were differentiated into functional RPE by neuroectodermal induction and mechanical purification. Most of the differentiated cells showed typical RPE morphologies, such as a polygonal-shaped epithelial monolayer, and transmission electron microscopy revealed apical microvilli, pigment granules, and tight junctions. These cells also expressed molecular markers of RPE, including Mitf, ZO-1, RPE65, CRALBP, and bestrophin. The generated RPE also showed phagocytosis of isolated bovine photoreceptor outer segment and secreting pigment epithelium-derived factor and vascular endothelial growth factor. Functional RPE could be generated from SNM in our method. Because SNMs have several advantages, including the capability of expansion for long periods without loss of differentiation capability, easy storage and thawing, and no need for feeder cells, our method for RPE differentiation may be used as an efficient strategy for generating functional RPE cells for retinal regeneration therapy.</P>
Off-road 엔진에서 WGT와 VGT장착에 따른 효율 및 특성 비교
신재식(Jaesik Shin),강정호(Jungho kang),하형수(Hyeongsoo Ha),정학섭(Haksup Jung),표수강(Sukang Pyo) 한국연소학회 2016 한국연소학회지 Vol.21 No.4
The aim of this study is to compare the effectiveness of turbo chargers on engines for off-road use when combined with WGT and VGT technologies. The effectiveness of turbo chargers was measured and performance was compared using a functional model. Exhaust characteristics were compared using WGT and VGT technologies through a gas analyzer. Results showed VGT technology was more effective at high RPM compared to WGT technology. When it came to maximising turbo performance, VGT was more effective than WGT in every test. WGT and VGT produced similar exhaust NOx levels, whereas the VGT was more effective on the PM.
Off-road 엔진의 EGR율에 따른 촉매코팅 DPF의 자연재생율 예측
신재식(Jaesik Shin),강정호(Jungho Kang),하형수(Hyrengsoo Ha),정학섭(Haksup Jung),표수강(Sukang Pyo) 한국연소학회 2016 한국연소학회지 Vol.21 No.3
This paper aims to predict oxidation amounts of catalyst and heat produced through passive regeneration on DPF according to different EGR rates and loads of off-road engines. Soot oxidation model and parameter assumption model were used for the test. Engine data were measureed with 25%, 50% and 75% of 1600 RPM loads and with 0% and 30% of EGR rates in order to estimate parameters. Oxygen levels calculated on the DPF downstream and oxygen levels measured were compared through all of the experimental conditions for validating the model. Oxidation rates on DPF according to different EGR rates and oxygen levels on the DPF downstream were estimateed successfully, which can be applied for off-road vehicles.