논문현황

INSTITUTE FOR ADVANCED ENGINEERING

지능기계시스템센터 Numerical Modeling and Performance Prediction of COS Hydrolysis Reactor in an Integrated Gasification Fuel Cell in terms of Thermo-Chemical Transport Phenomena

· 저자

Jung-Hun Noh, Dong-Shin Ko, Seung-Jong Lee and Deog-Jae Hur


During the recent decades, global warming by greenhouse gas evolution has attracted worldwide attention and ever increasing strict regulations thereon have become institutionalized as international policies. In the process, more environment-friendly power generation technologies have been developed utilizing fossil fuels with a view to timely commercialization. As one such “clean coal” technology, an Integrated Gasification Fuel Cell system is a promising power generation means where a carbonyl sulfide (COS) hydrolysis reactor is installed downstream of coal syngas to remove acidic gas constituents such as H2S and COS. The most significant design parameters affecting performance of the COS hydrolysis reactor were selected to be gas hourly space velocity (GHSV), reaction temperature, and length ratio, and numerical modeling was performed considering heat and fluid flow transfer as well as chemical reaction kinetics. Effect of the selected design parameters on the variation of conversion rate and reactant gas mixture concentration were comprehensively investigated to predict performance of the COS hydrolysis reactor. Stochastic modeling of reactor performance was finally performed using Monte Carlo simulation and linear regression fitting.


지능기계시스템센터 Natural convection flow around heated disk in cubical enclosure

· 저자

Dong-Bin Kwak, Jung-Hun Noh and Se-Jin Yook


In this study, a numerical analysis of the natural convection characteristics around a circular disk in a cubical enclosure was carried out. The disk and the enclosure were used to simulate a wafer placed in a front-opening unified pod. The disk position, size, and temperature were considered as the main variables, and the effects of each variable on the isotherm, streamline, and local Nusselt number were examined. The results confirmed that the disk position and size in an enclosure had greater effects on the natural convection flow pattern than the disk temperature. Because air flowed in from the edge of the disk, the local Nusselt number was the highest at the edge of the disk. It was also found that a large disk size generated a plume and formed a new thermal boundary layer.


지능기계시스템센터 Optimization of the radial heat sink with a concentric cylinder and triangular fins installed on a circular base

· 저자

Dong-Bin Kwak, Hoon-Pyo Kwak, Jung-Hun Noh and Se-Jin Yook


In this study, a radial heat sink with a concentric cylinder and triangular fins installed on a circular base, that is, a heat sink representing a general shape of the heat sinks employed for most of the commercial LED light bulbs, was optimized in terms of mass and thermal resistance. A numerical study was performed by considering natural convection and radiation heat transfer, and was validated through experiment. The effects of various geometric parameters, that is, radius of heat sink base, number of fins, fin height, and radius of hollow cylinder, on thermal resistance and convectional heat transfer coefficient were investigated. Multiobjective optimization was conducted by using the weighted sum method and the genetic algorithm. As a result, Pareto fronts were obtained, and the thermal resistance and mass of the radial heat sink with triangular fins were reduced compared to those of the reference radial heat sink.


지능기계시스템센터 Effects of wall thickness and material property on inverse heat conduction analysis of a hollow cylindrical tube

· 저자

Jung-Hun Noh, Dong-Bin Kwak and Se-Jin Yook


In this study, we examined the effects of a hollow cylindrical tube’s thickness and material properties on estimated time delay and waveform distortion in a one-dimensional inverse heat transfer analysis model using the thermal resistance method and an input estimation algorithm. Results indicated a persistent time delay for various heat flux amounts applied to different tube thicknesses. As the tube thickness increased, the numerically determined temperature data also experienced a time delay, which affected the inverse heat transfer response curve. Results also indicated that the transient heat flux waveform estimated for different material properties showed higher levels of distortion for materials having relatively low thermal conductivity. These materials also exhibited greater time delays. To address these issues, we applied a Fourier number (a dimensionless number representing the tube’s thickness and material properties) and proposed an equation to calculate sharpness, which can subsequently be used to predict probable time delays and heat flux waveform distortion. In conclusion, a correction is required when a low Fourier number is used in inverse heat transfer analysis.


지능기계시스템센터 A study on improving bone conduction speaker performance by electromagnetic prediction and performance distribution by statistical analysis method

· 저자

Dong Shin Ko, Deog Jae Hur, Tae Won Park and Jai Hyuk Lee


The present paper is focused on the stochastic characteristics of the electromagnetic force, one of the performance parameters for the bone conduction speaker which is one of the devices in the “smart glass”. The design parameters were taken as significant, affecting the electromagnetic force. Characteristic analysis of significant parameters was considered by using the factorial design method. Significant factor of main effect was selected via fractional factorial design method. Main effect and interaction of selected factor were analyzed applying the full factorial design method. The independency of the selected parameter and their significant interaction were examined by using the F-test method. Linear and non-linear characteristics for the selected parameters and performance were examined by creation of the median point within the analysis results for significance analysis. Therefore, prediction model derived non-linear regression model from the central composite design of response surface method. For probability distribution of the electromagnetic characteristics, related prediction model and Monte Carlo simulation method were applied. Electromagnetic performance prediction result showed 98.5 % level and improved maximum 99.8 % reliability level under 3σ level of dimensional management. In view of this, such stochastic design approach could improve design efficiency via verification of individual design parameters’ effect on the performance levels, thereby proving design reliability based on the object levels.


지능기계시스템센터 A study of optimization for vibration performance and electromagnetic force of the bone conduction speaker actuator asymmetry

· 저자

Jai Hyuk Lee, Dong Shin Ko, Sang Youp Kwon, Jae Yong Kim and Deog Jae Hur


This study derives an optimal design of electromagnetic force, verifies the analysis of the optimum, and runs the vibration test to consider various properties of the optimal design in order to optimize the performance of the bone conduction speakers used in Smart Glasses, one of smart wearable devices. For performance factors that affect the electromagnetism of actuator in a bone conduction speaker which holds a magnetic structure, the diaphragm height, yoke pole height, magnet height, magnet and plate width, and coil turn number were selected. To analyze the properties of the performance factors, responsive factors needed to be classified first using fractional factorial design and full factorial design was used for influence analysis. The F-test was done as the means to conduct the valence test to show the independence and reciprocal action for selected performance factors, and it concluded that three independence factors were valid. Based on the valid performance factors, a regression equation to predict its performance was deducted and using the equation, an optimal design to maximize the electromagnetic force performance per component. To verify the characteristics of the optimal model, the finite element method (FEM) was used for analysis. Through electromagnetic analysis, magnetic flux density was obtained, and the particular information along with current and coil length contributed to deriving 0.052 N of electromagnetic force. After completing the frequency response analysis based on the electromagnetic force, it resulted in the 0.0772 mm of displacement at 590.12 Hz of resonant frequency. A sample model was fabricated, followed by vibration testing, after optimal design and analytical verification. Hence, it is verified that the optimal design method and the credibility of the analysis of this study is deemed very high. Furthermore, utilizing this mechanism would inspect the effect of the design parameter performance and increase the credibility and effic…


지능기계시스템센터 A study of optimization for vibration performance and electromagnetic force of the bone conduction speaker actuator asymmetry

· 저자

Jai Hyuk Lee, Dong Shin Ko, Sang Youp Kwon, Jae Yong Kim and Deog Jae Hur


This study derives an optimal design of electromagnetic force, verifies the analysis of the optimum, and runs the vibration test to consider various properties of the optimal design in order to optimize the performance of the bone conduction speakers used in Smart Glasses, one of smart wearable devices. For performance factors that affect the electromagnetism of actuator in a bone conduction speaker which holds a magnetic structure, the diaphragm height, yoke pole height, magnet height, magnet and plate width, and coil turn number were selected. To analyze the properties of the performance factors, responsive factors needed to be classified first using fractional factorial design and full factorial design was used for influence analysis. The F-test was done as the means to conduct the valence test to show the independence and reciprocal action for selected performance factors, and it concluded that three independence factors were valid. Based on the valid performance factors, a regression equation to predict its performance was deducted and using the equation, an optimal design to maximize the electromagnetic force performance per component. To verify the characteristics of the optimal model, the finite element method (FEM) was used for analysis. Through electromagnetic analysis, magnetic flux density was obtained, and the particular information along with current and coil length contributed to deriving 0.052 N of electromagnetic force. After completing the frequency response analysis based on the electromagnetic force, it resulted in the 0.0772 mm of displacement at 590.12 Hz of resonant frequency. A sample model was fabricated, followed by vibration testing, after optimal design and analytical verification. Hence, it is verified that the optimal design method and the credibility of the analysis of this study is deemed very high. Furthermore, utilizing this mechanism would inspect the effect of the design parameter performance and increase the credibility and effic…


지능기계시스템센터 Evaluation of stress distribution with wind speed in a greenhouse structure

· 저자

Deog-jae Hur, Jung-Hun Noh, Hyun ju Lee and Hyoung woon Song


In this paper, stress distribution for a structurally stable greenhouse is considered in the present paper with subsequent investigation into the detailed stress distribution contour with the variation of self-weight and wind pressure level designation method under wind velocity of less than 30 m/sec. For reliable analysis, wind pressure coefficients of a single greenhouse unit were modeled and compared with experiment with correlation coefficient greater than 0.99. Wind load level was designated twofold: direct mapping of fluid dynamic analysis and conversion of modeled results into wind pressure coefficients (CP). Finally, design criteria of EN1991-1-4 and NEN3859 were applied in terms of their wind pressure coefficients for comparison. CP of CFD result was low in the most of the modeled area but was high only in the first roof wind facing and the last lee facing areas. Besides, structural analysis results were similar in terms of stress distribution as per EN and direct mapping while NEN revealed higher level of stress for the last roof area. The maximum stress levels are arranged in decreasing order of mapping, EN, and NEN, generating 8% error observed between the EN and mapping results under 30 m/sec of wind velocity. On the other hand, effect of dead weight on the stress distribution was investigated via variation of high stress position with wind velocity, confirming shift of such position from the center to the forward head wind direction. The sensitivity of stress for wind velocity was less than 0.8% and negligible at wind velocity greater than 20 m/sec, thus eliminating self-weight effect.


신소재공정센터 Corrosion-Erosion Behavior of MgAl2O4 Spinel Refractory in Contact with High MnO Slag

· 저자

J. Jeon, Y. Kang, J.H. Park and Y. Chung


The corrosion and erosion behavior of spinel refractory of different compressive strength has been investigated for refractories in contact with a high MnO slag for producing manganese ferroalloys. The finger rotating test (FRT) was adopted to evaluate the degradation behavior at 1550 °C under a rotating condition of 150 rpm. The sample with higher compressive strength (Sample C1) showed higher corrosion resistance than Sample C2. In Sample C1, the refractory progressively corroded from the surface to the inner region by chemical corrosion, while mechanical erosion of the refractory suddenly occurred in Sample C2 as a result of the penetration of the slag within the refractory and the rotating energy.


신소재공정센터 지르코니아 전해질을 이용한 단실형 고체산화물 연료전지의 전기화학 특성

· 저자

박희정, 주종훈, 양재교, 진연호, 이규형


Single-chamber solid oxide fuel cells (SC-SOFCs) consist of only one gas chamber, in which both the anode and the cathode are exposed to the same fuel-oxidant mixture. Thus, this configuration shows good thermal and mechanical resistance and allows rapid start-up and -down. In this study, the unit cell consisting of La0.8Sr0.2MnO3 (cathode) / Zr0.84Y0.16O2-x (electrolyte) / Ni-Zr0.84Y0.16O2-x (anode) was fabricated and its electrochemical property was investigated as a function of temperature and the volume ratio of fuel and oxidant for SC-SOFCs. Impedance spectra were also investigated in order to figure out the electrical characteristics of the cell. As a result, the cell performance was governed by the polarization resistances of the electrodes. The cell exhibited an acceptable cell-performance of 86 mW/cm2 at 800℃ and stable performance for 3 hs under 0.7 V.


신소재공정센터 Synthesis of Gd-doped CeO2 by ultrasonic spray pyrolysis with salt-assisted decomposition and its electrical and mechanical properties

· 저자

Hee Jung Park, G.B. Kim, S.J. Jung, Y.I. Lee, Jae-kyo Yang, Yun Ho Jin, and Y.H. Choa


Much attention has been paid to acceptor doped-ceria as a promising solid electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs) due to its high oxygen-ion conductivity. However, poor sinterability leading to high grain boundary resistance and weak mechanical properties have limited its commercialization. In this work, ceria nanoparticles were synthesized via ultrasonic spray pyrolysis using salt-assisted decomposition (SA-USP) to enhance the sinterabililty of the ceria. The effects of the quantity of added salt on the nanoparticle-characteristics were examined. Highly dense ceria (relative density ~ 97.5%) was obtained by sintering the nanoparticles at a temperature as low as 1300 oC and its mechanical and electrical properties were investigated. The hardness and the oxygen-ion conductivity of the ceria with high density were reasonably good, ~ 14 GPa and above 10−3 S/cm at the IT-SOFC operating temperatures.


바이오자원순환센터 Upgrading the fuel properties of sludge and low rank coal mixed fuel through hydrothermal carbonization

· 저자

김대기, 박세용, 박기영


학회지(년도) Energy (2017) Vol (No.), 페이지 141, 598-602


바이오자원순환센터 Conversion of organic residue from solid-state anaerobic of livestock waste to produce the solid fuel through hydrothermal carbonization

· 저자

양승규, 김대기, 한성국, 김호, 박세용


학회지(년도) Environmental Engineering Research (2018) Vol (No.), 페이지 23(4), 456-461


바이오자원순환센터 Estimation of the characteristics with hydrothermal carbonization temperature on poultry slaughterhouse wastes

· 저자

김호, 한성국, 송은혜, 박세용


학회지(년도) Waste Management & Research (2018) Vol (No.), 페이지 36(6), 535-540