자동차 조향장치용 Long Shaft의 정밀 냉간단조 최적공정설계에 관한 연구

김태범 공주대학교 대학원 2015 국내석사

The ‘Long shaft’ of an automotive steering system has a function transferring the rotational energy to steering gear box arising from rotation of steering when the driver will change the direction of the vehicle. Currently the ‘Long shaft’ will be manufactured by using of drawing process however it affects the product quality due to severe bending effect during the production and it brings rise in costs due to higher material loss. The purpose of this research is for application of ‘Cold forward extrusion’ process. Advantages of the ‘Cold forward extrusion’ is the minimizing of bending effect of the product and further minimized material loss through an input of necessary material quantity at the production. To apply of this kind of ‘Cold forward extrusion’ method first the research was proceeded mold-ability and forming load by extrusion angle of bottom die and performed the research about the effect of the Calibration land for improvement of the bending problem arising from forming on product’s characteristics. In this research, in order to know the influence of the extrusion angle comparison analysis performed by using ‘3D Rigid-plastic FEM’ analytic results of the angle range from 30º till 60º and assigned variables for each 5º. Further comparison analysis performed by using ‘3D Rigid-plastic FEM’the role of the ‘Calibration land’which avoids or compensates the bending problem arisingfrom forming and the impact on forming in case of installing 1-land, 2-land and 3-land.

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.

전기 자동차 배터리 화재 진압용 진동 노즐 상방향 방사 기술 연구

김기성 공주대학교 일반대학원 2024 국내박사

ABSTRACT* A Study on a Upward Injection Technology with Fluidic Oscillation Nozzle for Suppressing Fire of Electric Vehicle Batteries Ki-Sung Kim Department of Mechanical Engineering Graduate School of Kongju National University Cheonan, Korea (Supervised by Professor Sung-Young Park) In response to the climate change crisis and to foster low-carbon green growth, countries worldwide are progressively regulating the use of internal combustion engine vehicles, aiming to reduce petroleum energy consumption and curb exhaust gas emissions. Simultaneously, there is a growing promotion of environmentally friendly vehicles, including electric cars. However, a significant challenge arises as a considerable portion of these eco-friendly vehicles, particularly electric cars, are susceptible to large-scale fires. The thermal runaway of batteries during a fire can initiate a chain reaction of electrochemical reactions within the battery cells, leading to widespread fires that result in substantial human and material losses. In recent studies on fire suppression methods during thermal runaway of electric vehicle batteries, various approaches have been proposed and implemented in the field. These include smothering with fire blankets, placing the fire vehicle in an assembled basin, and directly pouring water onto the fire vehicle. However, addressing the challenges posed by the intense heat and explosions during thermal runaway is not easily achievable, and there is a significant issue of requiring a substantial amount of water. Additionally, a recent innovation involves the use of an upward injection device that sprays water from the vehicle underside towards the battery area. Nevertheless, this approach faces difficulties in accessing the vehicle's underside, and the spraying area is limited and restrictive. To develop fluidic vibrating nozzles for an upward injection device, a 3D model was designed. Drawing inspiration from the base model of a windshield spray nozzle, design parameters influencing the fluid spray angle and vibration frequency were identified. When comparing the injection angle and frequency as a result of flow analysis by changing the radius of curvature of the mixing chamber and the width and length of the inlet side, the IW 5.2 model had an angle of 41 [deg] and the widest injection angle with a frequency of 84.75 [Hz]. However, in order to secure the minimum vehicle ground clearance height of the mobile upward injection device, the length of the rear end of the nozzle inlet was shortened and the exit side curvature radius and exit side width length were changed. As a result of analysis, the injection angle and frequency were taken into consideration. When the base model had an angle of 42 [deg], it was judged to be most suitable with a frequency of 88.61 [Hz]. To validate the operational performance of the optimized nozzle model, individual units were fabricated and tested. The mobile upward injection device consisted of three rows of 100 mm * 100 mm pipes, with two nozzles arranged in each row and an additional two nozzles placed on the main firefighting water supply line, resulting in a total of eight nozzles. The device was designed with a height of 115 mm or less to facilitate access underneath vehicles. It was equipped with one-touch connectors to easily attach to the fire station's hose connectors. For convenience in device mobility and vehicle undercarriage access, casters (movable wheels) and an adjustable handle were attached. The performance test results of the prototype upward injection device indicated that the tested vehicle, with a ground clearance of 178 mm, provided sufficient clearance for the mobile upward injection device. The spray angle and fluid vibration frequency of the nozzle were within the expected range, ensuring an ample spray area during operation. Upon reviewing the results of this study, compared to traditional basin-type firefighting equipment, the installation time and cost were significantly reduced. Furthermore, in comparison to the upward injection device, the convenience and accessibility of the product, including its height and width, were favorable. Therefore, it is judged suitable for application across various models of electric vehicles. In addition, it is hoped that these techniques will help research the development of electric vehicle fire suppression devices in the future.

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.

천연소재 기반 하이드로젤 및 고체반응 공정을 통한 펩타이드 합성법 개발

박용묵 한국교통대학교 일반대학원 2017 국내박사

peptide synthesis via solid state reaction process The research of hydrogel based on natural material for wrinkle treatment is giving rise to great attention in accordance with the growing interests in beauty and anti-aging. Accordingly, the research of biomaterials having a long period biological stability is conducted by introducing in biomaterial having high biological reliability. The existing hyaluronic acid based products used for various applications have been reported the disadvantage of easy decomposing under the existence of enzyme in vivo. In this research, this disadvantage can be overcome by introducing a dopamine group into the hyaluronic acid via an in situ crosslinking to create a copolymer hydrogel which has significant high stability. Two kinds of precursors were prepared for the synthesis of hydrogel. Firstly, precursors called HA_DP were prepared by introducing dopamine groups into the hyaluronic acids having different molecular weights. Secondly, precursor named chitlac can be prepared by conducting a coupling reaction between chitosan and lactose. Finally, the biomaterials named hydrogel can be synthesized through Michael addition reaction and Shiff base reaction between HA-DP and chitlac. Several hydrogels were prepared for further toxicity tests and other bio-function evaluation studies. The physical properties such as pH, complex viscosity, and strength and extrusion pressure of the synthesized hydrogels have been evaluated. Other bio-functions and degradation studies when treating hydrogel with enzyme have also been done. In addition, the injection effects and the comparison data with other existing filler products have also been provided in this research. The single-dose toxicity study was conducted through a cytotoxicity evaluation method by treating rats with hydrogels. Elastin inhibition tests to assess the bio-function effects of the synthetic hydrogels were also been conducted. In summary, through this study, a long lasting hydrogel filler product having excellent bio-functions can be developed. And developing a commercially available filler product is definitely the further aim of this research. Taltirelin is a TRH(Thyrotropin-releasing hormone) analog, which is used in cure brain diseases in Japan. It has been used to cure brain disease rather than mental illness. Existing manufacturing process of Taltirelin was solution phase reactions with low yield and high manufacturing costs. In this study, Solid phase synthetic process of alpha form Taltirelin with high yield and high quality is introduced. Unlike the existing solution reaction, Solid phase reaction is a convenient manufacturing process with high yield and high quality. Controlling polymorphism of drugs is important in the pharmaceutical industry. Differences in crystal forms cause several problems in bioavailability, stability and industrial properties. Taltirelin, a central nervous system activating agents, has two crystal form (α- and β-forms). The α-form is chosen as a dosage form, which is metastable in crystallization slurry. The solvent effect on the crystallization behavior of the polymorphs was investigated. Polymorph of Taltirelin was identified through the analysis of the crystalline microscope, XRD, Raman spectroscopy, DSC, TTGA, FT-IR, SEM. The α-form of Taltirelin was controlled Through the supersaturation, crystallization modes (cooling, evaporation, drowning-out crystallization) Crystallization process study is conducted such as solvent, supersaturation, initial concentration of Taltirelin, ratio of the solvent and non-solvent, temperature, agitator mixing speed. The study found that crystallization polymorph is depending on the process parameters of solvent, supersaturation concentration, initial solvent concentration.

금속 입자가 고정화된 탄소 형광 입자를 이용한 박테리아 진단 및 사멸 연구

핫메드이라즈 한국교통대학교 일반대학원 2019 국내석사

The innovative approach on developing bacteria biosensor with high antibacterial activity have emerged as an important role. Recently, fluorescence material such as fluorescent carbon dot (FCD) has widely utilized as colorimetric bacteria biosensor due to its simplicity, rapidity and sensitivity. However, FCD have no sufficient antibacterial activity; hence, combining antibacterial agent such as metal nanoparticle with FCD would be necessary to simultaneously detect and eradicate bacterial contamination. In these works, colorimetric bacteria biosensor with high antibacterial activity was designed by immobilizing metal nanoparticles into catechol-functionalized FCD via metal-catechol interaction. In the first study, hybrid cationic FCD with silver nanoparticle (Ag) was relied on electrostatic interaction between material and bacteria for detection, and accumulation of Ag on bacterial membrane for killing. In the second work, the bacteria detection and killing of hybrid alkaline phosphatase (ALP)-sensitive FCD with cesium tungsten oxide (CsWO3) was depended on the ALP concentration and phothothermal ablation under near infrared (NIR) irradiation. Both approaches demonstrated high sensitivity towards E. coli and S. aureus with excellent bacteria killing efficiency. Thus, these studies offer promising method for the future bacteria detection and eradication.

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.

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.

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.

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.