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Recently, the driving performance that maximizes driving pleasure, exhaust sound quality, and quietness have been recognized as important elements according to the demands of clients. Technology has been dramatically developed while the evaluation and improvement of the exhaust system have been attempted using various methods to meet the requirements of clients, the largest problem in designing the exhaust system is to maximize performance by forming the optimal back pressure and flow velocity and to reduce the generated noise and vibration. The objective of this study is to propose an optimal geometry of an exhaust system for sports sedans with a V6 and above engine. To achieve this, an experiment was conducted as follows. Before a prototype was fabricated, an exhaust system was designed and the fluid flow was analyzed. A pressure transducer was installed in the prototype, and the exhaust pressures on the exhaust system were measured at idle, medium and high engine speeds. Noise and vibration were also measured to analyze the impact of confluence geometry on the silence of vehicle. Finally, wheel horsepower, torque from wheels were analyzed using a chassis dynamometer to identify an output difference according to confluence chamber geometry and propose an optimal geometry.

Recently, interest in light-weight vehicle research is spreading swiftly across the globe. This is part of efforts to reduce CO2 emissions in many countries of the world, including developed countries. Magnesium alloys represent light-weight, metallic materials with a density of 1.74 g/cc, the lowest of commercial metallic materials. Conventionally, magnesium alloy has a higher viscosity than aluminum alloy and its solidification velocity is remarkably fast. Thus, magnesium alloys can incur more casting defects than aluminum alloys. Traditionally, a die-casting process consists of filling the die cavity with the molten metal under high pressure. Thus mass fabrication process of magnesium alloys is die casting and machining process only, currently. In this study, we focus on the magnesium vacuum die-casting process for the AM60 material for automotive parts. This investigation includes the part design, solidification and structural simulation, mold making, vacuum die-casting process development, a mechanical property test, and a durability test.

The anisotropic properties of polyethylene terephthalate film resulting from its manufacturing process are quantitatively investigated in terms of its optical, mechanical, and photoelastic aspects. Transmission ellipsometers and a Jones‐matrix‐based analysis software together with a 4 × 4 Berreman‐matrix‐based analysis software are adopted to determine the wavelength‐dependent in‐plane birefringence, the principal refractive indices, and the orientation of the optical axis. Mechanical anisotropy is characterized in terms of the elastic compliance tensor components using the measured azimuthal angle‐dependent Young's modulus and Poisson's ratio. From the measured variation of the wavelength‐dependent in‐plane birefringence as a function of tensile stress, the dispersive photoelastic coefficients are obtained for a few sample azimuthal angles, and the components of the photoelastic tensor are determined. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 152–160

Let X be a commutative normed algebra with a unit element e (or a normed field of characteristic different from 2), where the associated norm is sub-multiplicative. We prove the generalized Hyers-Ulam stability of a mean value-type functional equation, f(x)&minus, g(y)=(x&minus, y)h(sx+ty), where f,g,h:X&rarr, X are functions. The above mean value-type equation plays an important role in the mean value theorem and has an interesting property that characterizes the polynomials of degree at most one. We also prove the Hyers-Ulam stability of that functional equation under some additional conditions.

Etanercept is a dimeric genetic recombinant glycoprotein consisting of Fc domain of human Immunoglobulin G1 and the extracellular domain of human tumor necrosis factor (TNF) receptor type II. Etanercept exerts therapeutic effects on inflammatory diseases such as rheumatoid arthritis and juvenile idiopathic arthritis by neutralizing biological activities of TNFα/Lymphotoxin (LT) α. Mochida Pharmaceutical and LG Chem have developed syringe, pen, and vial products of Etanercept BS (biosimilar) as the first biosimilar of Enbrel in Japan. The active ingredient of those products "Etanercept biosimilar 1" has the identical primary structure to that of Enbrel. The development of the Etanercept BS, including evaluations of quality attributes, nonclinical and clinical studies was performed in accordance with "Policies on Assurance of Quality, Safety and Efficacy of Biosimilars". The quality attributes of Etanercept BS were similar to those of Enbrel, and the binding affinities to TNFα/LTα, TNFα neutralizing activity, nonclinical pharmacokinetics and toxicological profiles of Etanercept BS were comparable to Enbrel. Additionally, the pharmacokinetic profile and efficacy of Etanercept BS were equivalent to those of Enbrel and there was no clinically significant difference in safety profiles between them in Phase I and Phase III clinical studies. The marketing approval application of the Etanercept BS with the same indications as Enbrel filed by Mochida Pharmaceutical was approved in January 2018 and the products will be launched by Ayumi Pharmaceutical in the near future. The Etanercept BS, which is as highly effective as Enbrel is expected to make beneficial therapies more easily accessible to patients.

The significance of this study lies in the importance of (1) nondestructive testing in defect studies and (2) securing the reliability of breast cancer prediction through thermal analysis in nondestructive testing. Most nondestructive tests have negative effects on the human body. Moreover, the precision and accuracy of such tests are poor. This study analyzes these drawbacks and increases the reliability of such methods. A theoretical model was constructed, by which simulated inner breast tissue was observed in a nondestructive way through thermal analysis, and the presence and extent of simulated breast cancer were estimated based on the thermal observations. Herein, we studied the medical diagnosis of breast cancer by creating a theoretical environment that simulated breast cancer in a real-world setting, the model used two-dimensional modeling and partial differential equation (PDE) thermal analysis. Our theoretical analysis, based on partial differential equations, allowed us to demonstrate that non-wounding defect detection is possible and, in many ways, preferable. The main contribution of this paper lies in studying long-term estimates. In addition, the model in this study can be extended to predict breast cancer through pure heat and can also be used for various other cancer and tumor analyses in the human body.

The recent trend in automotive industry is characterized by the replacement of existing metal materials with composite ones or the combination of both for lightweight parts. This study 1) created single lap joint specimens of SPCC used for automobile frame and four adhesives; epoxy, urethane, acrylic, mixed (urethane and acrylic) and rivets to bind dissimilar materials of CFRP necessary for weight lightening, and 2) performed a tensile shear test on adhesive bonding versus adhesive bonding with rivets. In summary, this study investigated on the bonding performance of different specimens: bonding strength, shapes of the failure surface, and the effect of rivets on bond strength.

The Electric Power Steering (EPS) or Motor Driven Power Steering (MDPS) mechanism proves to be a bright prospect among passenger vehicles ensuring better vehicle safety and fuel economy. The car manufacturers are focusing on the production of Rack type EPS system (REPS). This paper describes the development of concurrent simulation technique using TruckSim and control strategy for analysing RMDPS control system with a dynamic vehicle system. A full Truck vehicle model interacting with RMDPS control algorithm was concurrently simulated on a sinusoidal steering input. The dynamic responses of vehicle chassis and steering system resulting were evaluated and compared with proving ground experimental data. The comparisons show reasonable agreement on steering wheel torque, lateral acceleration and yaw rate. This concurrent simulation research leads the possibility of RMDPS performance evaluation of Truck and Semi-bonnet cars.

In this study, structural analysis for the seat frame of automotive was carried out using finite-element analysis (FEA) technique and comparative analysis of the designs of lightening method, while not degrading the strength and stability of the frame. Maximum equivalent stress and maximum deformation amount on the whole seat frame were analyzed by employing the loading condition of passengers on the back and cushion frames, which were made of steel as in the current seat frame of automotive. Moreover, an additional structural analysis of a seat frame that is made of carbon fiber reinforced plastic (CFRP), instead of the currently using steel material, was performed. The result of this analysis showed that the maximum displacement is increased when using CFRP, instead of steel. In addition, the lower density property of CFRP materials has the potential to reduce the weight of the frame when compared with that of the steel material. Therefore, this result suggests that the steel material that is being currently used in most automotive must be reduced. Overall, this study identifies the structural safety of the seat frame of automotive by comparing the distributed strength of different materials.

We developed a reflection ellipsometer so that one can measure the extremely small optical anisotropy of a rubbed polyimide alignment layer, without being disturbed by the residual anisotropy of the substrate. The optical anisotropy of the alignment layer was measured as rubbing strength was increased, and the measured anisotropy was compared to the retardation obtained by using a transmission-type ellipsometer, to confirm the reliability of our reflection ellipsometer. With this measured anisotropy we could verify the formation of an alignment layer by rubbing, and could quantitatively evaluate the formation of the alignment layer. Keywords: Ultra-small optical anisotropy, Reflection ellipsometry, Rubbed polyimide, Alignment layerOCIS codes: (120.2040) Displays; (120.2130) Ellipsometry and polarimetry; (310.5448) Polarization, other optical properties

Thus far, solders used in electronics remain lead-based. Pb-free solutions in electronic components and systems are receiving increased attention in the semiconductor and electronics industries. Pb-free materials currently in used are Sn-37Pb, Sn-4Ag and Sn-4Ag-0.5Cu/Ni plate joints. In this study, solder alloys were used at high temperatures for artificial aging processing that was performed at for 0hr, 100hr, 200hr, 400hr, 600hr and 1000hr. The SP test was conducted at and . As a result, the maximum shear strength of all the specimens decreased with the increase in artificial aging time and temperature of the SP test. In addition, Pb-free solders showed higher total fracture energy compared with Sn-37Pb at high temperatures. The mechanical properties of Sn-4Ag-0.5Cu solder/Ni plate joints remained in excellent conditions in electronic parking systems at high temperatures.

The creep properties of Lead-free solder joints were evaluated by Shear Punch (SP) method. Lead-free solder joints with Sn-4Ag, Sn-4Ag-0.5Cu and Sn-4Ag-1.0Cu solder tested and compared to the lead solder joint with Sn-37Pb. SP creep tests were performed at temperature of 30, 50 and 80°C. For the SP method, constant shear stresses from 3 to 22 MPa were applied into the SP specimen(10 × 10 × 0.5 mm). From the SEM, IMC layer of Cu6Sn5 were observed on the interface between solder and Cu. From the SEM and EDX, the Lead-free solder joints have much thicker interfacial IMC layer than the Sn-37Pb solder joint. From the power law relationships, the Lead-free solder joints show superior creep resistance than the Sn-37Pb solder joint. And among Lead-free solder joints, at 30 and 50°C, the ternary SnAgCu solder joints have high creep resistance than the binary SnAg solder joint. Sn-4Ag-1.0Cu solder joint shows the best creep resistance at 30°C, and Sn-4Ag-0.5Cu solder joint shows the best creep resistance at 50°C. However, at high temperature 80°C, all of the Lead-free solder joints have similar creep properties. The activation energy were expressed with creep strain rate and temperature. The ternary SnAgCu solder joints have the higher activation energy than the binary SnAg solder joint at 17.68 and 18.72 MPa. Average activation energy of Lead-free solder joints were lower than that of Sn-37Pb 75.11 kJ/mol. The average activation energy of Sn-4Ag-1.0Cu, Sn-4Ag-0.5Cu and Sn-4Ag solder joint at high stress is 102.68, 62.52 and 58.61 kJ/mol, respectively.

Highly efficient colored perovskite solar cells that exploit localized surface plasmon resonances in ultrathin subwavelength plasmonic nanoresonators are demonstrated. Localized resonances in ultrathin metal nano-strip optical resonators consisting of an array of metallic subwavelength nanowires on a transparent substrate, fabricated by using low-cost nanoimprint lithography over a large area, lead to a sharp peak in a reflection spectrum for distinctive color generation with angle-insensitive property up to 60°, and simultaneously transmit the complementary spectrum of visible light that can be efficiently harvested by the perovskite solar cells for electric power generation. The plasmonic color filter-integrated perovskite solar cells provide 10.12%, 8.17% and 7.72% of power conversion efficiencies with capabilities of creating vivid reflective red, green and blue colors. The scheme described in this work could be applied to a variety of applications such as power-generating decorations, tandem cells, power-saving wearable devices and energy-efficient reflective display technologies.

We performed this study to compare the pharmacokinetic (PK), immunogenicity, and tolerability profiles of etanercept between LBEC0101, a proposed biosimilar, and Enbrel®, the reference biological product. A randomized, double-blind, single-dose, two-treatment, two-period, two-sequence, crossover study was conducted in 48 healthy males. In each period, a single dose of LBEC0101 or Enbrel® was subcutaneously injected at 25 mg and serial blood samples for PK evaluation were collected up to 648 h post-dose. Serum etanercept concentrations and anti-drug antibodies (ADA) were measured using an enzyme-linked immunosorbent assay and an affinity capture elution assay. Log-transformed maximum concentration (C max) and area under the concentration–time curve (AUCinf) were compared. Tolerability was also evaluated. The serum concentration–time profiles were almost overlapped between LBEC0101 and Enbrel®. Geometric mean ratio (90% confidence intervals) for C max and AUCinf of LBEC0101 to Enbrel® were 1.02 (0.92–1.13) and 0.96 (0.87–1.05), respectively, which were within a conventional bioequivalence criteria of 0.80–1.25. ADA development was also comparable. Both drugs were well tolerated. LBEC0101 showed similar PK, immunogenicity, and tolerability profiles to Enbrel® after a single subcutaneous injection in healthy males. LBEC0101 can be further developed as a potential etanercept biosimilar (ClinicalTrial.gov identifier: NCT01725620).

Fracture energy was analyzed for FSW (Friction Stir Welding) joint in accordance with the tool rotation speed and feed rate in the thermo-mechanically affected zone. Al6061-T6 sheet with thickness 5mm was welded with 9 conditions (tool rotation speed: 900, 1000, 1100rpm, feed rate: 270, 300, 330mm/min). Tool with shoulder diameter of 18mm and probe diameter of 5mm was used. Specimen size was 10×10×0.5mm. The MSP (Micro Shear Punch) test was carried out to evaluate the load-displacement properties of FSW sheet along the center line of cross section of weldment. The maximum fracture energy was 0.771 J at the tool rotation speed of 1000 RPM and the feed rate of 300 mm/min, which was about 35.9 % of the minimum value. The reason is considered to be that the shape and distribution of precipitates in the weld zone were different and affected the weld strength and ductility.

Recent trend of the automobile industry is improving fuel efficiency and decreasing exhaust gas through lightweight parts because of strict environmental regulations. Carbon fiber reinforced plastics (CFRP) have been studied to reduce the weight of automotive parts because they have higher specific strength and elasticity-to-weight ratio than conventional steel. In the CFRP manufacturing process, the compressive process using Sheet Molding Compound (SMC) has been applied to fender, roof and trunk lid, etc., which are exterior materials of automobile because of its excellent productivity. However, in order to apply CFRP to automotive seat frame, the manufacturing process should be selected considering the shape and material properties. In this study, we conducted about the increase of the material properties and the improvement of SMC process in order to fabricate the automotive seat frame by using CFRP.

Complete novel software for MDPS for the simulation and analysis is proposed for steering engineers. The software, MSAS, which can provide the functionality for MDPS Simulation, Analysis & Synthesis, is based on the steering system model, vehicle model and control logic. As the suppliers provide the control logic as a black box, this software is capable of using any type of black box logic or white box control logic that can be developed by logic designers. In addition, this software will be synthesized with the suppliers’ s-function control logic and RMDPS together.

In most cases, graphite is using as a construction material for bipolar plates in PEM fuel cells. Graphite has a stabilized chemical reaction and excellent electrical conductivity. However, it also has weaknesses in that it is costly and prone to gas leaks because of its structural properties. Graphite has a porous structure, so graphite plates are thick for preventing these gas leaks. Even though, gas retention is still an issue, and bipolar plate thickness may conversely need to be increased further. Finally, graphite is difficult and expensive to manufacture via machining because of how brittle it is. Metal is a very attractive material for the industrial fields. Some engineers expect to overcome the weaknesses of graphite as a construction material for bipolar plates through the implementation of metallic substitutes. Metal is inexpensive and easy to manufacture while boasting a high-density structure and good electrical conductivity. However, metal has one weakness: its tendency toward corrosion. This study focused on commercial stainless steel’s corrosion behavior in a standard PEMFC operating environment during a 100-hour time frame. We investigated for changes in the microstructure using OM, SEM, and XRD, for corrosion properties using ICP, and for electrical properties using Potentiodynamic polarization.

This research aims to study the new paradigm of NDE measurement which allows the identification of defect locations and sizes of a certain structure by measuring its surface temperature after applying heat. STS which has a certain defect is applied by the heat of 70000W by a heater. Its difference of STS surface temperature is measured by using Infrared thermography. The estimated result of STS experiment and that of theoretical analysis of Flex-PDE are compared and analyzed to diagnose STS defect. Moreover, this study can save time and money and improve accuracy in contrast to the existing ultrasonic NDE experiment. In addition, the new paradigm of NDT/NDE by reverse-engineering will be valid if the data of thermal analysis and temperature distribution from the specifications of many materials is accumulated and verified.

Recently, the various welding methods are used in the coupling method of product for the streamlining of complex products, simplification of manufacturing process, and decreasing process time a variety of industries. In this welding area, the friction welding technique has many advantages such as the mass production of rapid and highly reliable product and eases of automation, reduction of process time etc. so the domestic/external many studies are conducting. In this study, the Spindle speed, Up-set pressure as the necessary process variables for friction welding were change variously by using the round bar specimen of Al6061-T6 and Al7003-T6 Aluminum material, so the friction welding performance of the specimen by each change was compared and analyzed. In order to comprehend the friction welding performance, the frictional pressure was fixed with 20MPa, the spindle velocity was changed with 1,000, 1,500, 2,200rpm, and the Up-set pressure was changed with 35, 50, 65MPa for producing, so the performance by the specimen was compared and analyzed through the final tensile strength test. In addition, the effects of the friction welding on the specimen were examined through the analysis on the welding part hardness of the each friction welded aluminum specimen. In the result of the study, it showed the highest welding characteristic with the tensile strength 250.5MPa by applying 1,000rpm spindle velocity, 50MPa Up-set pressure compared to the lowest tensile strength 171.6MPa. In addition, as the result of hardness test, the hardness of specimen after conducting the friction welding of specimen decreased compared to the hardness of the pure material in the welding boundary, so it is judged that the measure to minimize the effects of the frictional heat by minimizing the friction welding time is needed.

This is to predict the equation of steady-state creep strain rate and rupture life of Lead-free solder joints and to observed the fractographies of the surfaces of the fractured solder joints using the SP creep test method. In this research, Sn-4Ag, Sn-4Ag-0.5Cu, Sn-4Ag-1.0Cu and Sn-37Pb solders are used. So as to compare the Lead-free solder alloys with lead(Pb) containing solder alloys. In addition, SP creep tests are held at temperature of 30, 50 and 80¢™C. And the shear stresses used in the research are in the range of 3 to 22 MPa. The microstructure characterization and fractographic analysis of the fractured solder joints are conducted to fully describe the creep behavior of the solder joints. Increasing the testing temperature from 30 to 80°C has some effect on the fracture behavior of ternary SnAgCu solder joints during creep testing. The increased temperature made the joints more vulnerable to the brittle interfacial fracture. In addition, Sn-37Pb solder joint, dimples in the fractured surfaces are much smaller than that of the Lead-free solder joints. Also using the creep data, we obtained a prediction equation of steady-state creep strain rate and rupture life for Lead-free solder joint in this research.

Reflow soldering process is essential in electronic package. Reflow process for a long time results from the decrease of reliability because IMC is formed excessively. Solder alloys of Sn-37Pb and Sn-Ag with different kinds of Cu contents (0, 0.5 and 1 wt.%) as compared with Ni and Cu plate joints are investigated according to varying reflow time. The interfaces of solder joints are observed to analyze IMC (intermetallic compound) growth rate by scanning electron microscope (SEM). Shear test is also performed by using SP (Share-Punch) tester. The test results are compared with the solder joints of two different plates (Ni and Cu plate). IMCs are formed on Cu plate interfaces after reflows in all samples. Ni3Sn4 and IMCs are also formed on Ni plate interfaces. The IMC layer forms are affected by reflow time and contents of solder alloy. These results show that mechanical strength of solder joints strongly depends on thickness and shape of IMC.

FCC Unit (Fluid Catalytic Cracking Unit) is a mechanical device used to convert bunker C oil into high quality gasoline. During the refining operation, pressure vessel of FCC unit operates in high-temperature and high-pressure environment. Careful structural analysis and design are necessary for such equipment.In this paper, FEA (Finite element analysis) of the FCC unit was performed to evaluate its structural stability. The equivalent stress of the FCC unit was investigated and compared against the ASME code design specifications.The area of high stress concentration with maximum stress higher than the prescribed value was analyzed locally to carefully evaluate the stress.CA nozzle in the FCC unit was found to have significant margins for factor of safety and was redesigned for weight reduction. Tensile test was carried out to verify the integrity of the welded parts. Tensile strength of the welded partssatisfies all design requirements.

The speed change performance of transmissions has become a serious issue because of the increase in the inertia moment that has accompanied increases in engine output and transmission size. Therefore, it is necessary to develop better wear resistant friction materials. In this study, an appropriate sintered friction component for the synchronizer ring of a diesel manual transmission was developed, and its bonding characteristics were analyzed. That is, a process for bonding an Fe-based base material and Cu-based sintered friction material was developed. BSE and EDX analyses of this bonding layer were conducted, along with a shear strength test, to determine the bonding characteristics.

Since the spot welding process was completed in a very short time and there were many factors affecting the generation of welding defects, it was difficult to control all experimental factors of welding. Additionally, it was hard to monitor the distribution of stress in practical cases such as vehicle bodies. The purpose of this study was to investigate the applicability of infrared thermography for the evaluation of spot weldability in the view of fatigue life. In this research, infrared(IR) stress analysis adopting an infrared thermography as nondestructive evaluation of spot weldability was investigated. Using temperature and IR stress distribution obtained by an infrared camera from adiabatic heat expansion under a repeated load of sinusoidal waves, we estimated the fatigue quality index(FQI) of spot welded specimens. We also evaluated in terms of FQI and corrected the S-N curve from the original fatigue life curve of base metals.

High tensile strength steel (HS40R) and galvanized steel (EZNCEN) are extensively used as components of vehicle bodies because they satisfy environmental standards and improve fuel economy. Because vehicle body sheets are becoming thinner and stronger, it is difficult to satisfy the design standards of spot welding joints. This research presents the optimization of the welding condition for various welding variables of a spot welding specimen by genetic algorithm (GA). When the welding condition optimization of spot weldment is performed using finite element method. The fatigue strength prediction method using FEM is useful for the prior evaluation technique that can predict the fatigue strength of spot weldment.

In this study, shear punch-creep (SP-Creep) at Sn-4Ag/Cu pad the joint was tested by using environment-friendly Pb-free solder alloy Sn-4Ag of electronic components. Pb eutectic alloy (Sn-37Pb) joints limited to environmental issues with reflow time (10sec, 30sec, 100sec, 300sec) according to two types of solder alloy joints are compared and evaluated by creep strain rate, rupture time and IMC (Intermetallic Compound) behavior. As the results, reflow time increases with increasing thickness of IMC can be seen at overall 100sec later in case of two solder joints on the IMC thickness of Sn-4Ag solder joints thicker than Sn-37Pb solder joints. In addition, when considering creep evaluation factors, lead-free solder alloy Sn-4Ag has excellent creep resistance more than Pb eutectic alloy. For this reason, the two solder joints, such as in the IMC (Cu6Sn5) was formed. However, the creep resistance of Sn-4Ag solder joints was largely increased in the precipitation strengthening effect of dispersed Ag3Sn with interface more than Sn-37Pb solder joints.

In this paper, we compared, through experiments, the hysteresis characteristics in the load of the push rod, that is generated in the booster cylinder according to the time of the instantaneous actions made by the driver in stepping on and releasing the clutch pedal. In addition, we performed separated experiments to identify how the hysteresis characteristics of the pedal effort generated in the pedal unit and the hysteresis characteristics of the pedal effort that occurred in the booster push rod when the driver stepped on the clutch pedal, appeared in varied form, in a case when the compressed air of 8.0bar was applied into the internal booster and in another case without applying the compressed air. As the experimental results, it was found that when the compressed air was applied, the stroke of the push rod has increased and thereby the maximum load continued to be applied to the booster. Also it was confirmed that the load applied to the pedal unit when you step on the clutch pedal was found to be 25kgf when unapplied showing an increase of more than three times compared to 7.5kgf recorded when the compressed air was applied, which will accordingly cause an increase in degree of fatigue of the driver.

This thesis conducted a comparison analysis via an experiment on clutch pedal effort hysteresis response characteristic in accordance with oil line characteristic which makes up the drive system in automobile clutch. Clutch drive system experiment Jig was composed and used in comparison analysis of response characteristic in accordance with change in length of oil line possessing length of 4m and 8m and response characteristic in accordance with change in material using 8m length oil line possessing steel material, plastic material and rubber material with equivalent size data. The oil pressure applied to the oil line during the experiment was fixed at 8bar and the applied pedaling time was 0.3sec and 1.0sec. The result of the experiment showed the change in response characteristic aspect in accordance with oil line length change in clutch drive system was inadequate and was able to find out that the chance in response characteristic in accordance with oil line material change possessed the highest hysteresis response characteristic when steel material was applied. Through this study, we were able to understand the aspect of response characteristic change in hysteresis of clutch pedal effort in accordance with the characteristic change which makes up the oil line that composes clutch drive system. Keywords-clutch system; hysteresis; oil line length; oil line material; pedal load

The use of Pb-free solder alloys are just newly developed materials and their properties are not well established and documented yet. So, the research to substitute the critical problem of the Pb solder alloy are increasing widely. To evaluate the shear property of solder joints according to temperature condition was predicted through the Shear-Punch test and FEM. By using the database according to this, the reliability evaluation technology of the solder joints tries to be formulated. In this paper, the solder used the Sn37Pb, Sn-4Ag and the Sn4Ag0.5Cu. When solder melted in the copper interface, the solder joints according to reflow times, each modeling required for the Shear- Punch was made in consideration of the IMC layer thickness. And the micro shear punch test was performed to obtain material properties of solder according to temperature condition. The shear properties of specimen which was modeled was predicted through FEM. It compared with the test value in which it obtains from Shear-Punch. Also, a method which can obtain shear properties of Pb-free solder joints easily and quickly using FEM was proposed.

Ceramics are becoming one of the most important materials due to its good mechanical properties such as high strength, hardness, chemical safety, and high modulus of elasticity. Ceramics have been used widely as a material not only for construction, but also for vehicles, planes, and bones for the human body. Despite these advantages, ceramics have some limitations in actual use due to its brittle fracture characteristic. In order to develop ceramic belt in this study, the data regarding stiffness and strain is necessary. For this purpose, the sensitivities of maximum stress value and displacement are analyzed by applying the load change on ceramic belt with finite element method program.

High temperature and stress are encounted in power plants and vehicle engines. Therefore, determination of the creep-fatigue life of a material is necessary prior to fabricating equipments. In this study, life design was determined on the basis of the lethargy coefficient for different temperatures, stress and rupture times. SP-Creep test data was compared with computed data. The SP-Creep test was performed to obtain the rupture time for X20CrMoV121 steel. The integration life equation was considered for three cases with various load, temperature and load-temperature. First, the lethargy coefficient was calculated by using the obtained rupture stress and the rupture time that were determined by carrying out the SP-Creep test. Next, life was predicted on the basis of the temperature condition. Finally, it was observed that life decreases considerably due to the coupling effect that results when fatigue and creep occur simultaneously.

The fuel cell is considered to be a promising alternative energy source for the near future. A bipolar plate, which is the major component of the fuel cell, is always exposed to the moisture during operation, because one of the important functions of the bipolar plate is to facilitate water management within the cell. In order to use graphite composite materials as bipolar plate material for PEMFC, the effect of the moisture environment on the mechanical properties of bipolar plate is studied. Two types of specimens, one made of particulate graphite 90%-epoxy 10% composite 'with' woven carbon fabric, and the other 'without' carbon fabric, were fabricated. Both types of specimens were kept in three different environmental conditions: (1) dry at room temperature, (2) immersed in 85° C water for 100 h, and (3) immersed in 85° C water for 300 h. A series of experiments were performed with the samples of the two types: water absorption rate, strength and modulus from the bending and tensile tests were measured...

The high temperature creep properties of the generating plant's high temperature tube, pipe and header and such are very significant in accordance with long-time exposure to the high temperature and pressure environment. Not only this, but as the welding procedure is compulsory for the cohesion of components, the creep properties regarding the local microstructures of steel weldment are very important. In order to understand the creep properties regarding the local microstructures of steel weldment, the SP-Creep test which is easy to get sample from the field component was conducted. The local microstructure of steel weldment, that is, W.M. and B.M.'s microstructures were observed using the SEM. The rupture time of W.M. was longer as 110 % averagely in a same condition, which is the consequence of the difference of the microstructure. Each lethargy coefficient of B.M. and W.M. is evaluated by the relation among the temperature, load and the rupture time from SP-Creep Test. The life estimation equation can be induced by the transformation of Power-law. B.M. and W.M. for each 550 ℃ and 575 ℃, the very similar to normal temperature of the domestic thermal power generation in working, are estimated.

HS40R and EZNCEN are extensively used as components of vehicle bodies because they satisfy environmental standards and improve fuel ratio. Because vehicle body sheets are becoming thinner and stronger, it is difficult to satisfy the design standards of spot welding joints. This research presents the optimization of the welding condition for various welding variables of a spot welding specimen by genetic algorithm (GA). After obtaining the optimum welding condition by use of the genetic algorithm, the fatigue properties of HS40R and EZNCEN spot welded joints are evaluated by using the finite element method (FEM) to determine the durability and stability of a structure.

This paper shows how the number of lap of spot welded joints in automotive steel sheets changes the life -cycle transform of itself. There has been significant developments in the life extension of automotive steel sheets, as well as in passenger safety. We verified the validity of the S-N curve of materials by QSTS test. Moreover, we used EZNCEN and HS40R, which are commonly used as automotive steel sheets because of their excellence in increasing fuel efficiency. The purpose of research was to compare the fatigue life of multi - lap of spot welded joints to there. In addition s, we used the two different kinds of sheets together in the same welding under the same condition. Through this whole process, the hypothesis on the life cycle of lethargy coefficients was found to be in good agreement with the result of the experiment. That is, when using sheets of the same materials in one welding, the fatigue life of two laps of a spot welded joint was found to be much superior by EZNCEN 5~14%, HS40R 17~30%,and when using each sheet of different materials, we found the decrease in fatigue life by 6~16%. Finally, the best value from the data was chosen based on the experiment for the analysis of the fatigue life of each layer.

The welding quality of spot weldment is an important factor that significantly affects the strength, stiffness, safety, and other performance characteristics of vehicles. Therefore, quality control and fatigue life evaluation of spot weldment are necessary processes. This paper presents a method for determining the fatigue life of multi-lap spot weldment of a high strength steel sheet. In this method, the fatigue life is estimated using the lethargy coefficient, which is the total defect coefficient according to rupture stress and time obtained by the quasi static tensile-shear test. The DC potential drop method was used to check initiation and propagation of cracks in addition to the test. Also, in this study, we modified the lethargy coefficient by using the welding current. Furthermore, we define a specific lapping constant, which is a characteristic constant of 2 or 3 lap weldments. The fatigue life obtained by the fatigue estimate equation, which contains a specific lapping constant was compared and verified with an experimental value. Finally we analyzed the relation of lap number, welding current and fatigue life. This method can save processing time and cost for predicting the life cycle of a structure.

Various stainless steels were investigated to examine the new NDE technique. The new NDE technique did not depend on either magnetization or demagnetization of materials. The magnetic flux caused by stress concentration in stainless steels was examined with the ultra sensitive magnetic flux density meter. Tensile and biaxial fatigue tests were conducted to observe the magnetic flux leakage. Results from biaxial fatigue tests indicated that the measured magnetic flux curves had local periodical cycles with global increasing tendencies. The defect evaluation would be possible by comparing the flux density value at the stress concentration regions with that of other areas. [doi:10.2320/matertrans.MRA2007245]