The objective of this study is to find the optimal production process in the aluminum IMS core parts. To reduce the production process, the total stage was designed at a total of 2 stages and 3 stages. In the total 2 stages process, the production stage was divided into a shaft part production and a yoke part production. In the total 3 stages process, the yoke production stages were subdivided into the 2 stages for distributing the stress. The results were compared and analyzed in terms of effective stress, folding characteristics and load characteristics. The stress distributions according to the production total stages were almost the same, the yoke production stage was received high stress due to the high strain. Both the tubular shaft yoke and solid shaft yoke according to the production total stages did not have any problems in the production because there did not occur the folding, metal flow and under-fill. When the total 2 stages were employed, the load for producing the tubular shaft yoke and the solid shaft yoke was decreased by 35.0% and 27.1%, respectively. As the results, when the total 2 stages process is applied rather than 3 stages process, the product is produced quickly and it is expected to be advantageous for the production cost due to the low load.

The objective of this study is to optimize the diameter of tubular shaft yoke and solid shaft yoke, which are the core components of Al IMS for xEV. The processes of both products were designed totally 6 steps to manufactured the shaft part and the yoke part. The diameter of solid shaft yoke and tubular shaft yoke were changed from 20mm to 25mm and from 30mm to 35mm, respectively. Al 6082 was applied to the material of both products. The friction condition between die and material was employed Oil_Cold (Aluminum) with reference to the library in the program. The results were analyzed and compared in terms of effective stress, effective strain, and nodal velocity characteristics. The effective strain value for manufacturing the yoke part was higher than the shaft part because its part has a complex geometry. The value of nodal velocity was also higher with high effective strain region. However, in 6 stage process of tubular shaft yoke, although it had the high effective strain value, the nodal velocity value was the lowest due to the piercing process. The effect of shaft part diameter on effective stress in the tubular shaft was difficult to observe, however, in the solid shaft yoke, when the shaft part of one increased, the effective stress value was increased due to the larger yoke size.

The objective of this numerical study is to investigate the effect of shaft part’s diameter on the load distribution, under-fill, and metal-flow line characteristics in tubular & solid shaft yoke of Al-IMS. The outer diameter of tubular shaft yoke was changed from 30mm to 35mm, and the shaft diameter of solid shaft yoke was varied from 20mm to 25mm. In this results, the required load for production was linearly increased with increasing the tubular shaft yoke outer diameter. In the solid shaft yoke, the loads for the shaft part extending process were almost constant by 10,000kg, however, the loads for generating the yoke process, which were needed a lot of strain, were increased by 4,000kg with increasing the diameter of shaft part. The under-fill regions according to diameter of the shaft part were not observed in both products, and the metal-flow lines were also straight without folding phenomena.

The objective of this numerical study is to investigate the effect of aluminium material on the weight reduction in tubular shaft yoke and solid shaft yoke. The tubular shaft and the solid shaft were designed by 6 stage processes and the results were analyzed by using a finite element analysis method. The coefficient of friction was set to Oil_cold as referred to the analysis library. It was found that the weight was reduced as 65% with applying the aluminium alloy due to lower density than carbon steel. Von-mises stress values of applying aluminium alloy to the tubular shaft yoke and solid shaft yoke were lower than those of carbon steel because of the low yield stress of aluminium alloy. The folding and underfill phenomenon were not observed on the aluminium alloy in tubular shaft yoke and solid shaft yoke. From these results, the weight reduction of products and the extend life of dies can be expected when aluminium alloy is applied.

The objective of this study is to solve a problem that is occurred during the spline machining of tubular shaft yoke in both side IMS module. In order to simulate the problem, the movement direction of upper die was set as standard case and error case. The material of tubular shaft yoke was set to S20C as refer to the analysis library. The movement directions of upper die were separated with standard case and error case. The error case was set to simulate the problem in the spline machining of tubular shaft yoke. In order to solve the problem, the outer radius of upper die were modelled from 9.40mm to 9.44mm. The simulation results were analyzed and compared in terms of effective stress, metal flow line and folding phenomena characteristics. In case of the outer radius of upper die was 9.42mm, it was observed a relatively uniform effective stress distribution and had a straight metal flow line.

The objective of this study is to investigate the effect of torque variation on stress distributions in A-IMS module with both side tubular shaft yoke by numerically. In order to achieve this, the torque value was increased from 10Nm to 40Nm, and the results of this work were confirmed in terms of Von-mises Stress and the displacement characteristics. As the torque in module assembly was increased, the stress in tubular shaft york and splined shaft york was increased linearly. The indentation due to the steel ball was occurred in over 40N·m torque which is over the yield strength condition. The largest displacement occurred in the tubular shaft yoke 1, however, it does not exceed the yield strength and is supposed to be restored due to the elasticity. Therefore, it was concluded that there is no problem for the manufacturing of A-IMS with both side tubular shaft yoke.

The objective of this study is to find the optimal size of splined shaft in IMS module. Two methods were used in this study. One is for the investigation of effect of indentation process on the tubular shaft yoke, and another is for the investigation of effect of indentation process on splined shaft. The spline outer size of splined shaft was increased from 0.00mm to 0.20mm. The simulation results were analyzed and compared in terms of under-fill, metal flow, effective strain, Von-mises stress and load characteristics. The indentation load was increased with increasing of spline size. However, in case of 0.15mm outer diameter increasing, the separation load was decreased. The case of 0.10mm diameter increasing was the best spline size based on the low indentation load and high separation load.

The objective of this study is to investigate the effect of tubular shaft hole length on the A-IMS production process in numerically. The hole length of tubular shaft was changed from 69.5mm to 79.5mm for distribution of load and stress. Then, the tubular shaft was modeled by S20C which was referred to program library. At the same time, the results of numerical analysis were compared in terms of under-fill, metal flow, principal stress, Von-mises stress and load characteristics. In the results, the load and stress were increased at 4 stage when the hole length of tubular shaft was increased. Also, folding phenomenon was observed to intensify as increasing the hole length of tubular shaft by confirmation of metal flow.

The objective of this study is to solve the problem that was occurred during the spline processing in A-IMS tubular shaft. The upper dies were modelled conventional case and modified case. The tubular shafts were modelled as standard case and error case. The error case assumed production error of raw material. The material of tubular shaft was set to SCM 420H as refer to the analysis library. The simulation results were analyzed and compared in terms of metal flow, effective stress, and effective strain characteristics. The crushed and buckling problems were observed at the upper side of tubular shaft body when conventional upper die was applied. However, the crushed and buckling problems were solved when modified upper die was applied.

The object of this study is to improve the straightness in tubular shaft production. Die bearings of 1, 2 and 3 were inserted onto the lower die, respectively. In this study, the tubular shafts at the stage 5 were modelled as the standard and error cases. The error case assumes the production error of raw material. The coefficient of friction was set to the Oil_Cold conditions as referring to the analysis library. In the results, the effective stress was observed homogeneously on the distribution at yoke top in standard case. However, the effective stress was observed on the distribution at long section of yoke in case of the raw material with error. The metal flow line was stretched straight in standard case. On the other hand, the metal flow line was bent in all of error cases. The biggest displacement occurred when only one die bearing was applied. The smallest displacement occurred when two die bearings were applied in lower die.

The object of this study was to investigate for improving of the homogeneous stress distribution according to sliding cage geometry. In order to achieve this, the sliding cage were modelled as type A, type B and type C, then the sliding cage were applied at A-IMS assembly. The numerical simulation was performed by SOLIDWORKS SIMULATION commercial code and the torque range was applied from 10N·m to 40N·m at A-IMS assembly. The results of simulation were compared in terms of Von-mises stress, principal stress and displacement characteristics. Each stress of type B were the highest value. In other hand, Von-mises stress of type A and type C were less than yield stress.

This study was performed for the optimizations of A-IMS assembly by analyzing the stress distributions under the different torque conditions. In order to achieve this, the numerical simulation was performed by SOLIDWORKS commercial code and the torque range that applied on the A-IMS assembly was increased from 10 N·m to 40 N·m. The simulation results were analyzed and compared in terms of Von-mises stress, principal stress, and displacement characteristics. The maximum stress distributions was observed on the contact surface of needle bearing which is located between tubular and solid shaft. It was found that the fracture of A-IMS assembly won’t occur until 30 N·m of torque. Therefore, it was concluded that there is no problem for the manufacturing of A-IMS assembly.

The objective of this work is to investigate the A-IMS structural defects on the tubular shaft and solid shaft by analyzing the under-fill, metal flow, effective stress and load characteristics. The tubular shaft and solid shaft were designed 6 stage process by upper and lower die. The results were analysed by using a finite elements analysis method. The coefficient of frictions were set Oil_Cold conditions as referred to the analysis library. It was found that the actual under-fill phenomenon was not observed in both tubular and solid shaft. The load values of tubular and solid shaft were 520ton and 255ton, respectively. These values were under the limit of forging machine maximum value.

The objective of this study is to investigate the effect of closed and open type on the load characteristics and amount of waste in tubular shaft and solid shaft for optimal design. The open and closed type were designed by 6 stage processes and applied for analysis. The coefficient of friction was set to Oil_Cold conditions as refer to the analysis library. It is found that the actual underfill phenomenon was not observed on the closed and open type. The metal flow of the closed and open type are revealed that the folding phenomenon was not occurred, thus there is no problem in actual production. The load characteristics are similar from stage 1 to stage 3 due to the same geometry of upper and lower die. However, tubular shaft and solid shaft are decreased 26% and 32% load from stage 4 to stage 6. In case of open type, amount of waste of tubular shaft and solid shaft are 11g and 14g, respectively.

The objective of this study was to investigate the optimal design on the tubular shaft and solid shaft for A-IMS of commercial vehicle. The tubular shaft and the solid shaft were designed by 6 stage processes and the results were analyzed by using a finite element analysis method. The coefficient of friction was set to Oil_Cold conditions as referred to the analysis library. It was found that the actual underfill phenomenon was not observed on the tubular shaft and solid shaft. The metal flow of the tubular shaft and solid shaft revealed that the folding phenomenon was not occurred, so there is no problem in actual production. Principal stress and load characteristics of tubular shaft were higher than those of solid shaft since the tubular shaft has many deformation from stage 1 to stage 3.

We describe a survey of quasars in the early universe, beyond z ~ 5, which is one of the main science goals of the Infrared Medium-deep Survey (IMS) conducted by the Center for the Exploration of the Origin of the Universe (CEOU). We use multi-wavelength archival data from SDSS, CFHTLS, UKIDSS, WISE, and SWIRE, which provide deep images over wide areas suitable for searching for high redshift quasars. In addition, we carried out a J-band imaging survey at the United Kingdom InfraRed Telescope with a depth of ~23 AB mag and survey area of ~120 deg2, which makes IMS a suitable survey for finding faint, high redshift quasars at z ~ 7. In addition, for the quasar candidates at z ~ 5.5, we are conducting observations with the Camera for QUasars in EArly uNiverse (CQUEAN) on the 2.1m telescope at McDonald Observatory, which has a custom-designed filter set installed to enhance the effciency of selecting robust quasar candidate samples in this redshift range. We used various color-color diagrams suitable for the specific redshift ranges, which can reduce contaminating sources such as M/L/T dwarfs, low redshift galaxies, and instrumental defects. The high redshift quasars we are confirming can provide us with clues to the growth of supermassive black holes since z ~ 7. By expanding the quasar sample at 5 < z < 7, the final stage of the hydrogen reionization in the intergalactic medium (IGM) can also be fully understood. Moreover, we can make useful constraints on the quasar luminosity function to study the contribution of quasars to the IGM reionization.