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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers B
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 36, Issue 12 - Dec 2012
Volume 36, Issue 11 - Nov 2012
Volume 36, Issue 10 - Oct 2012
Volume 36, Issue 9 - Sep 2012
Volume 36, Issue 8 - Aug 2012
Volume 36, Issue 7 - Jul 2012
Volume 36, Issue 6 - Jun 2012
Volume 36, Issue 5 - May 2012
Volume 36, Issue 4 - Apr 2012
Volume 36, Issue 3 - Mar 2012
Volume 36, Issue 2 - Feb 2012
Volume 36, Issue 1 - Jan 2012
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Experimental Investigation of Thermal Conductivities of EG-based ZnO Nanofluids Manufactured Using Pulsed Wire Evaporation Method
Kim, Hyun-Jin ; Hwang, Kyo-Sik ; Shin, Hyun-Kyo ; Rhee, Chang-Kyu ; Lee, Gyung-Ja ; Yoon, Jong-Ho ; Jang, Seok-Pil ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 111~115
DOI : 10.3795/KSME-B.2012.36.2.111
In this paper, the thermal conductivities of ethylene glycol. based ZnO nanofluids manufactured using the pulsed wire evaporation method are experimentally measured using the transient hot wire method at temperatures in the range of
. For this purpose, ethylene glycol.based ZnO nanofluids with 1%, 3%, and 5.5% volume fractions were manufactured using the pulsed wire evaporation method. Transmission electron microscopy (TEM) was performed to investigate the suspension stability of the ethylene glycol.based ZnO nanofluids. Based on the experimental results, the thermal conductivities of ethylene-glycol-based ZnO nanofluids increase with increasing volume fractions of ZnO nanofluids. The maximum enhancement of the thermal conductivity is 26.5% for a volume fraction of 5.5% at
. Finally, the experimental results are compared with conventional models such as the Maxwell and Hasselman & Johnson models.
Measurement of Mechanical Properties of Thin Films Using a Combination of the Bulge Test and Nanoindentation
Jung, Bong-Bu ; Lee, Hun-Kee ; Park, Hyun-Chul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 117~123
DOI : 10.3795/KSME-B.2012.36.2.117
This paper discusses two different techniques used to measure the mechanical properties of thin films: the bulge test and the nanoindentation test. In the bulge test, a uniform pressure is applied to one side of the film. Measurement of the membrane deflection as a function of the applied pressure allows one to determine the mechanical properties such as Young`s modulus, and the residual stress. A nanoindentation test is performed by pushing an indenter tip into the specimen and then withdrawing it, and then recording the indentation force as a function of the indenter position. A modified King`s model is used to estimate the mechanical properties of the thin film in order to avoid the effects of the substrate layers. A combination of both the bulge test and the nanoindentation test can determine both Young`s modulus and Poisson`s ratio simultaneously.
Effects of Mechanically Different Environments on the Crawling Waveform of Caenorhabditis Elegans
Kim, Dae-Yeon ; Byeon, Soo-Yung ; Kim, Se-Ho ; Shin, Jennifer Hyun-Jong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 125~130
DOI : 10.3795/KSME-B.2012.36.2.125
The nematode Caenorhabditis elegans is a widely used model organism in biological research. Thanks to the availability of well-established knowledge about its neural connectivity, a wide range of studies have been attempted to uncover the relationship between behaviors and the responsible neurons. In our research, the adaptive behavior of C. elegans in solid environments with different surface rigidities is investigated, where the worm adapts to different mechanical stiffnesses by modulating its crawling waveform. The amplitude and wavelength of the crawling waveform decrease as the environment becomes more rigid. Interestingly, the mechanosensation-defective mutant shows different responses to the surface rigidity compared to those of the wild-type worm. To explain the adaptation process in mechanically different environments, we suggest a plausible neural circuit model.
Dependence of Nanoparticle and Combustion Characteristics of Gasoline Direct Injection Engines on Coolant Temperature
Lee, Hyo-Keun ; Choi, Kwan-Hee ; Myung, Cha-Lee ; Park, Sim-Soo ; Park, Jong-Il ; Han, Seung-Kook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 131~136
DOI : 10.3795/KSME-B.2012.36.2.131
This paper investigated the combustion and exhaust gas characteristics of gasoline direct injection engines for various cooling water temperature. The engine-out nanoparticle emission number and size distribution were measured by a DMS-500 equipped upstream of the catalyst. A CLD-400 and an HFR-400 were equipped at the exhaust port to analyze the cyclic NOx and total hydrocarbon emission characteristics. The results showed that the nanoparticle emission number greatly increased at low coolant temperatures and that the exhaust mainly contained particulate matter of 5.10 nm. THC also increased under low temperature conditions because of fuel film on the combustion chamber. NOx emissions decreased under high temperature conditions because of the increase in internal exhaust gas recirculation. In conclusion, an engine management system control strategy for driving coolant temperature up rapidly is needed to reduce not only THC and NOx but also nanoparticle emissions.
Effect of Multiple Injection on the Performance and Emission Characteristics of Lean Burn Gasoline Direct Injection Engines
Oh, Jin-Woo ; Park, Cheol-Woong ; Kim, Hong-Suk ; Cho, Gyu-Baek ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 137~143
DOI : 10.3795/KSME-B.2012.36.2.137
Currently, in order to meet the reinforced emissions regulations for harmful exhaust gas including carbon dioxide (
) as a greenhouse gas, technologies for reducing
emission and fuel consumption are being developed. Gasoline direct injection (GDI) systems have the advantage of improved fuel economy and higher power output than port fuel injection gasoline engine systems. The aim of this study is to examine the performance and emission characteristics of a lean burn GDI engine equipped with spray-guided-type combustion system. Stable lean combustion was achieved with a late fuel injection strategy under a constant operating condition. Further improvement in specific fuel consumption is possible with the introduction of multiple fuel injection strategies, which also increases hydrocarbon (HC) and nitrogen oxide (
) emissions and decreases carbon monoxide (CO) emission.
Mathematical Modeling for Estimation of Heart Work
Suh, Sang-Ho ; Kaptan, Yalin ; Roh, Hyung-Woon ; Song, Ji-Hoon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 145~151
DOI : 10.3795/KSME-B.2012.36.2.145
Evaluation of the heart work is starting to emerge as a new diagnostic tool for arterial diseases. The aim of this study is to develop a mathematical model for the estimation of heart work utilizing the pulse waves between two points of a vessel. In order to calculate heart work, medical data such as blood pressure waveforms (which are measured using a cuff) are utilized. The heart work is calculated by employing the modified Windkessel model together with the viscosity models of Casson or Herschel-Bulkely (H-B). The results indicate that the compliance values at the proximal and distal locations differ for the Casson and H-B models.
Analysis of Bypass Grafting Effects in Stenosed Coronary Arteries
Kim, Hyoung-Ho ; Suh, Sang-Ho ; Lee, Jeong-Sang ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 153~159
DOI : 10.3795/KSME-B.2012.36.2.153
Bypass anastomosis is frequently adopted for surgical treatments of stenosed coronary arteries. Optimal coronary bypass grafting should be investigated to improve the patency in arterial bypass techniques. The objective of this study is to analyze the effects of Y-grafting bypasses and T-grafting bypasses for various bifurcation and anastomotic angles. In order to find the optimal geometric configuration, the hemodynamic characteristics are obtained and compared with each other for different geometries. We found that both the left anterior descending artery (LAD) and left circumflex artery (LCX) blood flows were distributed evenly when the bypass grafting angle and bifurcated angle were
Numerical Modeling of Current Density and Water Behavior at a Designated Cross Section of the Gas Diffusion Layer in a Proton Exchange Membrane Fuel Cell
Kang, Sin-Jo ; Kim, Young-Bae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 161~170
DOI : 10.3795/KSME-B.2012.36.2.161
There are many factors to consider when attempting to improve the efficiency of fuel cell operation, such as the operation temperature, humidity, stoichiometry, operation pressure, geometric features, etc. In this paper, the effects of the operation pressure were investigated to find the current density and water saturation behavior on a cross section designated by the design geometry. A two-dimensional geometric model was established with a gas channel that can provide
to the anode and
and water vapor to the cathode gas diffusion layer (GDL). The results from this numerical modeling revealed that higher operation pressures would produce a higher current density than lower ones, and the water saturation behavior was different at operation pressures of 2 atm and 3 atm in the cathode GDL. In particular, the water saturation ratios are higher directly below the collector than in other areas. In addition, this paper presents the dependence of the velocity behavior in the cathode on pressure changes, and the velocity fluctuations through the GDL are higher in the output area than in inlet area. This conclusion will be utilized to design more efficient fuel cell modeling of real fuel cell operation.
Influence of Precooling Cooling Air on the Performance of a Gas Turbine Combined Cycle
Kwon, Ik-Hwan ; Kang, Do-Won ; Kang, Soo-Young ; Kim, Tong-Seop ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 171~179
DOI : 10.3795/KSME-B.2012.36.2.171
Cooling of hot sections, especially the turbine nozzle and rotor blades, has a significant impact on gas turbine performance. In this study, the influence of precooling of the cooling air on the performance of gas turbines and their combined cycle plants was investigated. A state-of-the-art F-class gas turbine was selected, and its design performance was deliberately simulated using detailed component models including turbine blade cooling. Off-design analysis was used to simulate changes in the operating conditions and performance of the gas turbines due to precooling of the cooling air. Thermodynamic and aerodynamic models were used to simulate the performance of the cooled nozzle and rotor blade. In the combined cycle plant, the heat rejected from the cooling air was recovered at the bottoming steam cycle to optimize the overall plant performance. With a 200K decrease of all cooling air stream, an almost 1.78% power upgrade due to increase in main gas flow and a 0.70 percent point efficiency decrease due to the fuel flow increase to maintain design turbine inlet temperature were predicted.
Effect of Outer Edge Flame on Flame Extinction in Counterflow Diffusion Flames
Chung, Yong-Ho ; Park, Dae-Geun ; Park, Jeong ; Yun, Jin-Han ; Kwon, Oh-Boong ; Keel, Sang-In ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 181~188
DOI : 10.3795/KSME-B.2012.36.2.181
The present study on nitrogen-diluted non-premixed counterflow flames with finite burner diameters experimentally investigates the important role of the outer edge flame in flame extinction. Flame stability diagrams mapping the flame extinction response of nitrogen-diluted non-premixed counterflow flames to varying global strain rates in terms of the burner diameter, burner gap, and velocity ratio are explored. There exists a critical nitrogen mole fraction beyond which the flame cannot be sustained, and also the curves of the critical nitrogen mole fraction versus the global strain rate have C-shapes in terms of burner diameter, burner gap, and velocity ratio. In flames with sufficiently high strain rates, the curves of the critical nitrogen mole fractions versus global strain rate collapse into one curve, and the flames can have the 1-D flame response of typical diffusion flames. Three flame extinction modes are identified: flame extinctions through the shrinkage of the outer edge flame with and without an oscillation of the outer edge flame prior to the extinction and flame extinction through a flame hole at the flame center. The measured flame surface temperature and a numerical evaluation of the fractional contribution of each term in the energy equation show that the radial conductive heat loss at the flame edge destabilizes the outer edge flame, and the conductive and convection heat addition to the outer edge from the trailing diffusion flame stabilizes the outer edge flame. The radial conductive heat loss at the flame edge is the dominant extinction mechanism acting through the shrinkage of the outer edge flame.
Visualization and 3D Numerical Analysis of the Circulation Flow of the Neutron Moderator in a Heavy-Water Nuclear Reactor
Eom, Tae-Kwang ; Lee, Jae-Young ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 189~196
DOI : 10.3795/KSME-B.2012.36.2.189
The heavy moderator acts as the ultimate heat-sink in an operating CANDU reactor. HUKINS has been developed to investigate moderator flow patterns. HUKINS consists of a 38.4-mm-thick cylindrical shell with a 0.95 m inner diameter and 88 sus-tubes that produce a total heat of 10 kW. A chemical visualization method was selected to estimate the occurrence of typical moderator flow patterns. Momentum-dominated flow, mixed flow, and buoyancy-dominated flow are detected under conditions of a heat load of 7.7 kW and input mass flow rates of 4, 7, and 11 L/min. The experimental results are similar to the results of a CFD simulation that consisted of approximately 1.9 million grids and was conducted using the k-
turbulence model. Therefore, both the present experiments and simulations using HUKINS, a 1/8-scale model, represent all three important flow patterns expected in the real CANDU6 reference reactor. Thus, it has been demonstrated that HUKINS could be useful in the study of CANDU6 moderator circulation.
Detonation Initiation via Surface Chemical Reaction of Laser-Ablated Aluminum Sample
Kim, Chang-Hwan ; Yoh, Jai-Ick ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 197~204
DOI : 10.3795/KSME-B.2012.36.2.197
We explore the evolution of metal plasma generated by high laser irradiances and its effect on the surrounding air by using shadowgraph images after laser pulse termination and X-ray diffraction (XRD) of aluminum plasma ablated by a high-power laser pulse (>1000 mJ/pulse) and oxygen from air. Hence, the formation of laser-supported detonation and combustion processes has been investigated. The essence of this paper is in observing the initiation of chemical reaction between the ablated aluminum plasma and oxygen from air by the high-power laser pulse (>1000 mJ/pulse) and in conducting a quantitative comparison of the chemically reactive laser-initiated waves with the classical detonation of an exploding aluminum (dust) cloud in air. The findings in this work may lead to a new method of initiating detonation from a metal sample in its bulk form without any need to mix nanoparticles with oxygen for initiation.
Development of Ultra-Supercritical (USC) Power Plant
Chang, Sung-Ho ; Kim, Bum-Soo ; Min, Taek-Ki ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 205~210
DOI : 10.3795/KSME-B.2012.36.2.205
For environmental reasons and because of our limited energy resources, high-efficiency power generation technology will be necessary in the future. Ultra-supercritical (USC) power generation technology is the key to managing the greenhouse gas problems and energy resource problems discussed in the Kyoto Protocol to the United Nations Framework Convention on Climate Change. Other countries and manufacturers are trying to build commercial power plants. In this paper, an efficient method of achieving near-zero emission operation of a high-efficiency fossil power plant using USC power generation is discussed. Development of USC power generation in Korea has been supported by the Korean government in two phases: Phase I was USC key technology development from 2002 to 2008, and Phase II is USC development and technology optimization from 2010 to 2017.
Combustion Characteristics of a Premixed Burner in a Stirling Engine for a Domestic Cogeneration System
Ahn, Joon ; Lee, Youn-Sik ; Kim, Hyouck-Ju ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 211~216
DOI : 10.3795/KSME-B.2012.36.2.211
The availability of thermal energy has been widely recognized recently, and the cascade usage of thermal energy from combustion has been encouraged. Within this framework, a 1-kW-class Stirling-engine.based cogeneration system has been proposed as a unit of a distributed energy system. The capacity has been designed to be adequate for domestic usage, which requires high compactness as well as low emissions and noise. To develop a highly efficient system satisfying these requirements, a premixed slot-type short-flame burner has been proposed, and a series of experiments has been performed to understand its combustion characteristics. Flame images have been captured to observe the dependence of the flame mode on the combustion load and air/fuel ratio. The exhaust gas has been sampled and analyzed to study the emission characteristics for each flame mode.
Exhaust Gas Recirculation System Applied to 56 kW Off-Road Vehicle to Satisfy the Tier 4 Interim Emission Regulation
Kang, Jeong-Ho ; Han, Joon-Sup ; Chung, Jae-Woo ; Jeong, Gun-Woo ; Cho, Gyu-Baek ; Lim, Jung-Ho ; Pyo, Su-Kang ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 217~224
DOI : 10.3795/KSME-B.2012.36.2.217
In general, transportation sources include both on-road vehicles and off-road equipment. Off-road vehicles have usually used diesel engines, which have the disadvantage of high NOx emission. Common rail direct injection (CRDI) and after-treatment systems have been applied to meet the exhaust gas emission regulations for diesel vehicles. In the present, agricultural machinery has satisfied the Tier 3 emission regulations by using waste gate turbocharger (WGT) and internal exhaust gas recirculation (EGR). In this paper, the combustion and emission characteristics of an EGR system applied to a 56kW off-road vehicle in non-road transient cycle (NRTC) mode have been investigated. The EGR map was made from foundation experiments determining the EGR duty for all engine operating conditions, and then this map was applied to the NRTC mode. Consequently, the NOx emission was reduced by the EGR system, and the Tier 4 interim emission regulations were satisfied by using both the EGR system and an after-treatment system.
Prediction of Pollutant Emissions from Lean Premixed Gas Turbine Combustor Using Chemical Reactor Network
Park, Jung-Kyu ; Nguyen, Truc Huu ; Lee, Min-Chul ; Chung, Jae-Wha ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 2, 2012, Pages 225~232
DOI : 10.3795/KSME-B.2012.36.2.225
A chemical reactor network (CRN) was developed for a lean premixed gas turbine combustor to predict the emission of pollutants such as NOx and CO. In this study, the predictions of NOx and CO emissions from lean premixed methane-air combustion in the gas turbine were carried out using CHEMKIN and a GRI 3.0 methane-air combustion mechanism, which includes the four NO formation mechanisms for various load conditions. The calculated results were compared with experimental data obtained from a modified test combustor to validate the model. The contributions of the four NO pathways were investigated for various load conditions. The effects of nonuniformity of the mass flux and of the equivalence ratio of the injector on the NOx formation were investigated, and a method of reducing the pollutant formation was suggested for the development of a sub-10 ppm gas turbine combustor.