Simultaneous reduction in the exhaust emissions by a high exhaust gas recirculation ratio in a dimethyl-ether-fuelled diesel engine at a low-load operating condition

Park, Su Han,Cha, Junepyo,Park, Sungwook,Lee, Chang Sik SAGE Publications 2012 Proceedings of the Institution of Mechanical Engin Vol.226 No.8

<P>The purpose of this study was to investigate the effect of the exhaust gas recirculation rate on the combustion and exhaust emission reduction characteristics of dimethyl ether fuel in a single-cylinder diesel engine. To investigate the effects on emission reduction, the test set-up was composed of a dimethyl ether supply system, a spray visualization system, an engine combustion system and an emissions analysis system. In this work, the spray visualization and exhaust emissions were measured using a high-speed camera with a metal halide lamp, a smoke meter and an emission gas analyser. The spray tip penetration and tip velocity of dimethyl ether fuel were lower than those of conventional diesel fuel. The reduction slope of the spray cone angle for dimethyl ether was less than that for diesel fuel owing to its low density and superior evaporation characteristics. The increase in the exhaust gas recirculation rate caused an extension of the ignition delay for dimethyl ether. During the extended ignition delay, the improved mixing characteristics influenced the slight decrease in the combustion period. An increase in the exhaust gas recirculation rate caused a significant reduction in the emission of nitrogen oxides. In addition, the soot emission was very low owing to the intrinsic characteristics of dimethyl ether (no direct carbon-carbon bonds). At the given equivalence ratio condition, the indicated specific hydrocarbon and indicated specific carbon monoxide emissions for dimethyl ether were extremely low when dimethyl ether spray was injected into the piston bowl (from 25 degrees before top dead centre to top dead centre). Also, in this case, a change in the exhaust gas recirculation rate for dimethyl ether combustion had minimal effects on the indicated specific hydrocarbon and indicated specific carbon monoxide emissions. These results suggest that the use of high exhaust gas recirculation with dimethyl ether fuel can achieve near-zero exhaust emissions (nitrogen oxides, soot, hydrocarbons and carbon monoxide).</P>

Prediction of wall impingement in a direct injection spark ignition engine by analyzing spray images for high-pressure injection up to 50 MPa

Park, Junkyu,Kim, Taehoon,Kim, Donghwan,Park, Sungwook Elsevier 2018 Fuel processing technology Vol.179 No.-

<P><B>Abstract</B></P> <P>This study was performed to analyze the wall impingement and fuel film formation in a DISI engine with injection strategies using image-based analysis and CFD. The direct injection engine uses a high-pressure injection strategy to improve the homogeneity of the air-fuel mixture, so the spray behavior was analyzed by spray visualization for various injection pressures, and the wall impingement was predicted for various engine operating conditions based on the acquired images. The mass distribution of the injected fuel was calculated using the injection profiles and the spray image, and the amount of fuel that impinges on the piston and wall (i.e., the geometric boundaries of the cylinder) was calculated using data from the spray behavior for various engine operation conditions such as load and engine speed. The image-based analysis was limited to understanding the influence of the injection strategy on the droplet behavior after wall impingement of the fuel spray. Therefore, CFD using KIVA 3 V code was additionally conducted to analyze the effects of the injection strategies on wall film formation and droplet rebounding reflecting in-cylinder conditions. In the early- and late-injection conditions, the initial piston position is high, and most of the injected fuel impinges on the piston. As the injection pressure increases, the injection timing at which wall impingement occurs is advanced because of the rapid spray development. The results of the 3D analysis for the temperature and the intake flow in the engine cylinder showed that both the wall impingement and the fuel film were reduced as the injection pressure increased because the fuel evaporation increased due to improved atomization.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A prediction method of wall impingement in DISI engines is introduced. </LI> <LI> Effects of injection pressure and injection timing on spray wall impingement are analyzed using image-based method. </LI> <LI> 3D CFD are used to analyze effects of the engine conditions on formation of fuel film. </LI> <LI> Higher injection pressure conditions can reduce formation of fuel film due to superior vaporization characteristics. </LI> </UL> </P>

Detection of Avian Influenza Virus from Cloacal Swabs Using a Disposable Well Gate FET Sensor

Park, Sungwook,Choi, Jaebin,Jeun, Minhong,Kim, Yongdeok,Yuk, Seong-Su,Kim, Sang Kyung,Song, Chang-Seon,Lee, Seok,Lee, Kwan Hyi Wiley (John WileySons) 2017 Advanced Healthcare Materials Vol.6 No.13

CsPbX3/SiOx (X = Cl, Br, I) monoliths prepared via a novel sol-gel route starting from Cs4PbX6 nanocrystals

Park, Sungwook,An, Mai Ngoc,Almeida, Guilherme,Palazon, Francisco,Spirito, Davide,Krahne, Roman,Dang, Zhiya,De Trizio, Luca,Manna, Liberato The Royal Society of Chemistry 2019 Nanoscale Vol.11 No.40

<P>We developed a facile synthesis of nanocomposite powders of CsPbX3 nanocrystals (NCs) embedded in silica. The synthesis starts from colloidal Cs4PbX6 NCs that are mixed with tetraethyl orthosilicate in the presence of nitric acid, which triggers the sol-gel reaction yielding the formation of SiOx and the conversion of starting NCs into CsPbX3 ones. The overall reaction delivers CsPbX3 NCs encased in a silica matrix. The resulting CsPbX3/SiOx nano-composite powders exhibited enhanced moisture and thermal stability in air. Also, when mixing different CsPbX3/SiOx samples having diverse anion compositions, no interparticle anion exchange processes were observed, which is a further indication that the silica matrix acts as a robust barrier surrounding the NCs. Finallly, we used these composites as down-converter phosphors on top of a blue light-emitting diode (LED), delivering nearly ideal white light emission with the Commission Internationale de l'Eclairage (CIE) color coordinates (0.32, 0.33).</P>

Effects of Nozzle Design Parameters of a Common-rail Diesel Injector on Nozzle flow and Spray Characteristics

( Junkyu Park ),( Donghwan Kim ),( Hyuckmo Kwon ),( Joonkyu Lee ),( Soohong Lee ),( Sungwook Park ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

This paper describes effects of nozzle design parameters including number of nozzle hole, spray angle, and HFR on nozzle flow and spray characteristics. Injection profiles were measured using Bosch method in order to analyze flowrate depending on the nozzle design parameters and spray visualization was performed under various injector driving conditions to compare the macroscopic spray behavior in terms of the spray tip penetration and the spray cone angle. The experimental results were validated against through the Hiroyasu equation after modifying adjustable constants to fit to high pressure injection region. The flowrate was proportional to the size of HFR, which means the static flow at 100 bar. Under various injection pressure, flowrate was proportional to square root of increment of injection pressure and corresponded well to the predicted formula based on the Bernoulli equation. As number of nozzle holes increased under fixed total flow rate condition, the slower spray development was observed due to reduced nozzle outlet diameter, and the spray cone angle was similar for the cases of various nozzle diameter. For nozzle condition in which the spray angle was changed from the reference (153°), there was no significant difference in terms of macroscopic spray characteristics, but the emission characteristics can be deteriorated due to differences in air entrainment in the cylinder.

다중 무선 방송채널에서 상호 관련 데이타 할당 방법

박성욱(Sungwook Park),정성원(Sungwon Jung) 한국정보과학회 2009 정보과학회논문지 : 데이타베이스 Vol.36 No.1

무선 환경에서의 방송은 클라이언트의 수에 상관없이 다수의 클라이언트들에게 데이타를 보낼수 있기 때문에 많은 관심을 이끌어왔다. 다수의 이전 연구들에서는 한 개의 독립적인 데이타를 최단시간에 획득하는 것을 목표로 했고, 한 질의어 내에 포함된 상호 관련된 데이타들을 동시에 획득하는 것에 대해서는 연구되지 않았다. 또한, 이러한 논문들에서는 질의어 내의 데이타들이 동일시간에 다른 채널 상에서 나타나지 않도록 할당하는 문제에 대해서만 연구되었고 질의어 요청 확률을 기반으로 한 각 데이타의 접근확률은 반영되지 않았다. 본 논문에서는 데이타를 할당하고 동시에 한 질의어 속에 포함된 모든 독립된 데이타들을 획득하는데 요구되는 평균응답시간을 최소화하는 새로운 기법을 제시한다. 성능 분석에서는 우리가 제시한 기법이 현존하는 다른 기법들 보다 좋은 평균응답시간을 보여준다. Broadcast in the wireless environment has drawn much attention because it is capable of sending data to clients regardless of the number of clients. Most previous researches have aimed at obtaining an independent data item in a minimum time. But, they have not been researched on simultaneously receiving dependent data items in a query. In addition, these papers have only researched allocation problem that have not been came out data items in a query in same time and different channels. The access probability of each data item based on query request probability have not been reflected. This paper proposes a new method of allocating data items and simultaneously minimizing average response time required in receiving all the dependent data items in a query. Our performance analysis shows that our proposed method gives better average response time over the existing methods.

Front End Carrier의 상부 구조에 따른 강성 비교 연구

박성욱(Sungwook Park),공태윤(Taeyun Kong),김재용(Jaeyong Kim),소원섭(Wonsub So) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

Front End Module is assembled to the front area of the vehicle. In the case of front crash, the Front End Module should be able to absorb the impact and the deformation of Front End Module should be minimized. If the vehicle’s hood deformed by crash is opened, it can make the wind shield of vehicle broken and injure passengers. Because deformed and opened hood can cause the additional accidents, the stiffness supporting hood is very important. The stiffness of all developed vehicles must be verified in the development stage through Hood Latch Retention Test. And the test must be controlled strongly. The stiffness supporting hood & latch has the relationship with the Front End Carrier’s upper structure. The Higher inertia of Upper Section is advantageous, but the upper section can not be secured often because of vehicle’s styling or engine room layout or limitation of cost & weight , ETC, and these factor is different according to the vehicles We have developed several vehicle’s Front End Module since 1999 and we will introduce some kinds of knowhow from the development history of 2 vehicle’ Front End Module.

클라우드 컴퓨팅 기반 통합기관제어체계에 관한 고찰

박성욱(Sungwook Park) 대한전기학회 2016 대한전기학회 학술대회 논문집 Vol.2016 No.10

전기자동차 배터리 성능저하 관리 제도

박성욱(Sungwook Park) 한국자동차공학회 2023 오토저널 Vol.45 No.7

클라우드 컴퓨팅 기반 통합기관제어체계에 관한 고찰

박성욱(Sungwook Park) 대한전기학회 2016 정보 및 제어 심포지엄 논문집 Vol.2016 No.10