스포일러 유무에 따른 승용차 후단부 유동 특성

김성하 국립공주대학교 대학원 2025 국내석사

This study was conducted to improve the aerodynamic characteristics of passenger cars, which are essential for enhancing fuel efficiency and driving stability. The research focuses on analyzing the flow characteristics around a vehicle with and without a spoiler. To achieve this, a CFD analysis and a scaled-down wind tunnel experimental setup were designed and utilized. The models used in this study were commercialized "A" vehicles from manufacturer H, with and without spoilers. The simulations were performed using Star CCM+, employing the SST - turbulence model. The CFD analysis results revealed that the spoiler significantly affected the separation point and flow direction of the airflow passing over the upper body of the vehicle. For the base model (without a spoiler), the flow was directed towards the ground at an angle of 13.5 °, while for the spoiler model, the angle was reduced to 3.5 °. This change led to an increase in airflow velocity under the vehicle and a corresponding rise in downforce. Compared to the base model, the CFD analysis showed that the spoiler model exhibited a 0.2% increase in drag coefficient and a 10.1% increase in lift coefficient. Additionally, the pitch moment was reduced by 14.4%, indicating improved vehicle stability. The results from the scaled-down wind tunnel experiments, although differing in magnitude, showed trends consistent with the CFD simulations. Specifically, the lift coefficient increase was more pronounced than the drag coefficient increase in both cases. By operating the wind tunnel at dynamically scaled speeds, the flow pattern changes observed in the experiments were similar to those in the CFD analysis. This study demonstrates that spoilers can significantly enhance downforce and vehicle stability without substantially increasing aerodynamic resistance. The findings can serve as fundamental data for product design and analysis in the automotive tuning market, as well as for simplified wind tunnel testing.

pH 민감형 탄소 형광 소재을 기반으로 약물전달 및 이미징 연구 : Synthesis of pH Responsive Fluorescent Carbon Dots for Tumor Targeted Drug Delivery and Imaging.

강은비 한국교통대학교 일반대학원 2018 국내석사

I developed system for nanoparticles based targeted Drug delivery system (DDS) promises to expand the therapeutic regimes by selectively delivering the drug candidates. This will effectively reduce the minimum effective dose and improve the therapeutic efficacy at equivalent plasma concentration. Firstly, we studied fluorescent carbon nanoparticles based target drug delivery with bio-imaging systems offer tremendous scope for future. We described Pluronic mimicking fluorescent nanoparticles (Plu-FNPs) surface decorated doxorubicin (DOX) via acid-cleavable hydrazone linkages with tumor target folic acid (FA) [Plu-FNPs-FA-DOX]. The acid labile of hydrazine linkage to DOX can easily break off by controlled pH inducing release of conjugated DOX at site of over-expressed folate receptors (FR). This nanoparticle system can deliver DOX to the target FR and trace the delivery pathway of cancer cells. The approaching platform demonstrates the selectivity and sensitivity of molecular targets, thereby able to maximize the therapeutic efficiency. In another approaching, mitochondria-targeted photothermal nanoparticles with the blocker 3-bromopyruvate (BP), delocalized lipophilic triphenylphosphonium (TPP) cations to target them to the mitochondrial membrane, and folic acid (FA) to target cancer cells. The carbonized polyethylene glycol grafted poly (dimethyl aminoethyl methacrylate)-q-catechol (F-PEG-g-PDMA-CCDP) was crosslinked with boronic acid-grafted polyethylene glycol-g-poly (dimethyl aminoethyl methacrylate) conjugated with IR825 as a near-infrared (NIR) responsive fluorescent agent, FA, TPP, BP (PEG-g-PDMA-FA/IR/TPP/BP). The F-PEG-g-PDMA-CCDP@PEG-g-PDMA-FA/IR/TPP/BP (F-FNP) showed in vitro anticancer activity to normal and cancer cell under NIR light treatments. The blocking of metabolic activity in mitochondria with a photothermal system might represent a new pathway for cancer therapy.

Highly and Rapid Procedure for Theranostic System using Stimuli-responsive Fluorescent Carbon Dots

Phuong, Pham Thi My 한국교통대학교 일반대학원 2019 국내석사

To overcome recent drawbacks of conventional techniques for the simultaneous integration of diagnosis and therapy approaches, the design and application of new therapeutic methods based on multi-responsive nanoparticles have been proposed which are more accurate, efficient, faster and simpler. Recently, fluorescent carbon dots became the most impressive candidate due to their nano-scaled size, owning excellent optical properties with tunable sensitivity, biocompatibility, environmental friendliness, and photostability. In these works, we have taken the advantages of fluorescent carbon dots to design cellular sensing systems for rapidly detecting the presence of bacterial and cancer cells in specific surrounding pH or redox environments based on fluorescent ON/OFF behavior or electrochemical signals. Subsequently, the systems could perform the near-infrared light induced-killing effect after irradiation based on photothermal temperature. Hence, these studies on stimuli-responsive fluorescent carbon dots systems have shown their potentials to be applied as a smart material with high sensitivity, biocompatibility, selectivity, and accuracy in biomedical applications.

In Situ Monitoring of Antifouling Surface and Cancer Diagnosis Based Stimuli-Responsive Conductive Polymer Dots

Nguyen Ngan Giang 한국교통대학교 일반대학원 2021 국내석사

In recent years, sp2 bond-bridged fluorescent polymer dots (PDs) carbonized from biomaterials have gained a lot of attention in bioimaging and diagnosis fields due to it with excellent properties such as biocompatibility, chemical stability, low toxicity, coatability, and tunable sensitivity. Moreover, attributed to it conductivity based on electron transfer, PDs could be a favourable candidate for electrochemical sensors. Here, we developed a sensing system relied on carbonized polymer dots which could be applied for cell-surface monitoring in accordance to fluorescent and electrochemical approach. In the first study, we utilized the use of Cu2+ as a quenching factor to promote the sensitivity of the cancer sensing accompanied by carbonized hyaluronic acid (HA) backbone for CD44 endocytosis of cancer cells. For another study, we optimized the pH sensitiveness of zwitterionic polymer dots under various pH levels to monitor cell proliferation and cell detachment. Attributed to hydrophobic-hydrophilic transition and chare transfer simultaneously happening, the system exhibited a favourable method for cell-surface monitoring. Both systems demonstrated high sensitivity and fast responses toward the changes between cell-surface interaction which was performed by electrochemical approach.

외부 민감형 탄소형광소재가 캡슐화된 무기나노입자 제조 및 암세포 치료 연구

베니 한국교통대학교 일반대학원 2019 국내석사

In recent years, fluorescence carbon dots (CD) have gained recognition due to the ability to incorporate drugs and excellent luminescence characteristic. However, further development such as functionalizing the CD structure or integrate it with an inorganic material is necessary to obtain a stimuli-responsive nanoparticle with desirable drug loading capacity. Here, we developed a drug delivery system based on a hybrid fluorescence carbon dots-inorganic nanomaterial which applied for stimuli-responsive bioimaging and nanocarrier. In the first study, we utilized the used of MnO2 as a quenching effect to increase the selectivity of biocompatible Hyaluronic Acid (HA) carbon dots to redox environment. For another study, we optimize the high pore volume of mesoporous silica nanoparticle (MSN) by encapsulated zwitterion CD and photosensitizer to achieve a pH-responsive nanoparticle. Both systems displayed sensitivity toward cancer environment which showed a promising potential for tumor diagnosis and therapy.

병원성 박테리아 검출을 위한 폴리머닷 코팅 전극 무선 바이오센서

조형준 한국교통대학교 일반대학원 2023 국내석사

Biosensor development for bacterial detection is critical to preventing infectious disease outbreaks caused by bacterial contamination. Recent studies have focused on colorimetric sensors, but high limit of detection (LOD) has restricted their application for sensitive bacterial detection. Here, we designed a smartphone-based electrochemical biosensor that uses coated electrodes to detect bacteria by modifying PDs to specifically bind or interact with various compounds on the outer membrane of bacterial cells. The first chapter designed a reusable, sensitive smartphone-based electrochemical biosensor which uses electroconductive boronic acid-modified polymer dot (B-PD)-coated electrode to detect bacterial contamination. For the second chapter, A rapid wireless electrochemical biosensor that can discriminate between gram-negative and gram-positive bacteria is designed for the selective detection of pneumonia pathogens in human sputum. The selective binding with the bacterial cell wall of gram-negative and gram-positive bacteria is achieved by utilizing colistin- and vancomycin-conjugated polymer dot-coated electrodes.

HP-LP EGR을 장착한 디젤엔진의 배기가스 배출특성 및 연료소비율에 관한 실험적 연구

이종인 공주대학교 대학원 2014 국내석사

LP-EGR system has an advantage the EGR rate may be enhanced without reducing an efficiency of a supercharger. By application of an LP-EGR system with such advantage to diesel engines with the existing application of HP-EGR and DOC as well as DPF techniques, an experimental study has been conducted on the effects on exhaust gas compositions and fuel consumption rates depending on engine rpm and torque rates. The NEDC mode of a Chassis Dynamometer was simulated on an engine dynamometer. A study was conducted on changes in discharge characteristics and fuel consumption rates of an exhaust gas in a transition region of LP-EGR as compared with conventionally applied HP-EGR, and optimum formation of a back pressure was found to be important to secure a high LP-EGR rate. Under low-speed, low-load conditions, the generation of BSNOx was reduced by 50% ~ 75% in comparison with HP-EGR. Under intermediate-speed, intermediate-load conditions, BSFC of LP-EGR was improved by about 1.3% ~ 2.1% compared with HP-EGR. While BSNOx of LP_EGR as compared with HP-EGR was reduced by an average of 13% under high-speed, high-load conditions. 2295 rpm / 247 Nm a condition, the BSNOx production of the LP-EGR is 20% lower than the HP-EGR. As a result of applying different back pressure conditions in high-speed and low-speed region of an engine in an NEDC mode evaluation, NOx generation of LP-EGR was reduced by 56% as compared with that of the Base HP-EGR. In the present article, an experimental study has been conducted on the effects on exhaust gas compositions and fuel consumption rates depending on the optimization of an LP-EGR system along with engine rpm and torque rates. According to the results, there was a reduction effect of exhaust gases without deterioration in fuel consumption rates through optimization of the LP-EGR system. However, under the conditions where condensate is produced, reliability considerations and avoidance methods are required.

전기차 배터리의 열폭주 긴급진압을 위한 70mm급 자체 분무가진 노즐 연구

오진동 국립공주대학교 대학원 2024 국내석사

Recently, due to global interest in global warming, regulations in the automobile industry are continuously being strengthened, and the development of electric vehicles is actively progressing. Electric vehicles use secondary batteries for energy storage purposes, and among secondary batteries, lithium-ion batteries with high energy density are mainly used. Lithium-ion batteries are vulnerable to external shock and heat, and internal and external factors can cause damage to the internal separator, resulting in thermal runaway. In this study, a nozzle optimization study was conducted to apply a fluidic oscillator to the upward spraying nozzle to study electric vehicle fire suppression devices. In the analysis based on the internal design variables of the fluidic oscillator, the maximum injection angle of each design variable was confirmed to be 68° for the MR 0.97 model, 71° for the IW 1.18 model, 62° for the OR 1.08 model, and 63° for the OW 1.16 model. To optimize the fluidic oscillator, analysis was conducted by combining models showing the maximum injection angle of each design variable. In both experiment and analysis, the MR+IW+OW model shows the largest injection angle and is judged to be a suitable model as a fluidic oscillator for spraying devices. To evaluate the fire suppression performance of the FON, a comparative experiment was conducted with the recently used ON injection method. As a result of the experiment, it was confirmed that the FON has a faster overall cooling rate than the ON, so it is judged to be suitable for extinguishing battery fires. The spraying device was manufactured based on the design model, and was designed and manufactured with a total length of 740 mm so that it could be mounted on a fire truck. In order to check the performance of the manufactured spraying device, the fire-fighting nozzle was connected and operated, and the water sprayed from the spraying device was sprayed over a wide area under the vehicle, so it is believed that it can be used in actual fire scenes.

2기통 가솔린엔진을 이용한 RE-EV용 엔진발전시스템에 관한 실험적 연구

구본석 공주대학교 대학원 2016 국내석사

Development of Hybrid Car such as EV, HEV, PHEV, is growing fast by focusing on exhaust gas and fuel efficiency due to fossil fuel depletion and reinforce of environmental regulation following by high oil price and global warming. However, there are some risks which shrink market share because of high price and low density of Energy. This is why RE-EV is focused as a new technology that expands mileage with pure-electronic energy which increases storage space with engine generating system. * A thesis submitted to the committee of Graduate School, Kongju Natioal University in partial fulfillment of the requirements for the degree of Master of Mechanical Engineering Conferred in August 2016. RE-EV utilizes actuating-electronic-motor while regular driving. After rack of battery, it recharges with engine power generation system. There should be examination gradually that engine and generator’s selection of storage, design, manufacture, and exam analysis to improve fuel efficiency and RE-EV is power performance. Moreover, specialized-module for RE-EV is required to promote standard engine and generator. The paper analyzes engine performance by 4 types of case studies that changes inspiratory pressure and cylinder pressure by 1,500 to 3,500rpm with ETC location and Surge tank as exam variables. This analysis is based on phenomenon of decreasing inspiratory pressure in high rev through 2 cylinder- MPI type gasoline engine analysis. As a results, engine air flow could be expand by inetia and pulsation effect, when a intake pipe is short. In case of decreasing surface of U-tube, there is no inetia and pulsation effect due to fast air circulation in high rev. It also confirmed that pulsation effect mitigates during increasing surge tank’s volume. In comparison results of engine performance, all cases show improvement of generating power and torque. Torque reaches 2500rpm to 103.6Nm which is better than standard intake system over 11Nm. Generating power showed 3500rpm to 34.4kW also over approximately 4.7kW.

Dual-responsive crosslinked Pluronic micelles as a carrier to deliver anticancer drug Taxol

압둘라 알 나하인 충주대학교 일반대학원 2012 국내석사

This research has been performed to deliver hydrophobic anticancer drug to reduce the limitations of the drug Taxol and its toxic effects to normal cell. A dual-sensitive biodegradable chemically crosslinked polymer (CCP) forming nanosized micelles bearing pH responsive covalent benzoic-imine bond and redox sensitive disulfide bond is reported as endocytosis based target delivery system to deliver hydrophobic anticancer drug paclitaxel. The polymer CCP has been successfully constructed between benzaldehyde grafted Pluronic (P-A) and amine end capped Pluronic having disulfide linkage (P-B) which were characterized by 1H NMR and GPC. DLS and TEM showed particle size and morphology before and after drug loading respectively. Depending on different acidic environment and dithiothreitol (DTT), kinetics of micelles stability was performed. In vitro release experiment indicates faster drug release at mildly acidic and higher reductive conditions. By using A549 cell line, toxicity of the polymer was evaluated where the result certifies the nontoxicity of the polymer. Cell killing efficiency of the paclitaxel entrapped within the hydrophobic core of the micelles was compared with the free drug. Finally, using the same cell confocal images of the drug loaded polymer was investigated. These biodegradable micelles are promising potential candidate in carrier based intelligent drug delivery system to deliver cytotoxic hydrophobic drug.