The Spent Nuclear Fuel (SNF) cladding serves as the first barrier that prevents the release of radioactive materials. It is very important to maintain cladding integrity in SNF management. It is known that the pinch load applied to the cladding can lead to Mode-3 failure and the cladding becomes more vulnerable to this failure mode with the existence of radial hydrides and other forms of mechanical defects. In this study, a numerical analysis process was proposed to scientifically and systematically evaluate the fracture resistance of cladding with reoriented hydrides under pinch load. The mechanical behavior and fracture of the irradiated cladding under pinch load can be evaluated by Ring Compression Test (RCT). Under the stress field generated by RCT, the cracks propagate more easily through radial hydrides than circumferential hydrides. The δ-hydride which form within the α-zirconium matrix causes a large expansion strain due to the volume difference and voids form at the interface between the hydride and the zirconium matrix. Chan demonstrated that the load needed to form voids and separate the hard hydride precipitates from the Zr matrix is considerably lower than that which initiates brittle fracture of hydrides using a micro-cantilever test. Therefore, we propose a microstructure crack propagation analysis method based on Continuum Damage Mechanics (CDM) that can simulate fracture of hydride, zirconium matrix, and Zr/hydride interface. CDM is possible to simulate the hydride, zirconium matrix, and interface cracking in a continuum model based on cladding deformation. The RCT simulation model was constructed from the microscopic images of irradiated cladding. A pixel-based finite element model was created by separating the hydride, zirconium matrix, and interface using the image segmentation method on a morphology operation basis. The appropriate element size was selected for the efficiency of the analysis and crack propagation using CDM. The force-displacement curves and strain energy from RCT were compared and analyzed with the simulation results of different element sizes. The finalized RCT simulation model can be used to evaluate the fracture resistance of the irradiated cladding under the quantified pinch load and to establish the failure criterion of fuel rods under pinch load. The advantages and limitations of the proposed process are discussed.

The evaluation of the damage ratio of spent nuclear fuel is a very important intermediate variable for dry storage risk assessment, which requires an interdisciplinary and comprehensive investigation. It is known that the pinch load applied to the cladding can leaded to Mode-3 failure and the cladding becomes more vulnerable to this failure mode with the existence of radial hydrides and other forms of mechanical defects. In this study, the failure resistance of Zircaloy-4 cladding against the pinch load is investigated using numerical simulations assuming the existence of radial hydrides. The simulation model is based on the microscopic images of cladding. A pixel-based finite element model was created by separating the Zircaloy-4 and hydride using the image segmentation method. The image segmentation method uses a morphology operation basis, which is a preprocessing method through erosion operation after image expansion to enable normal segmentation by emphasizing pixels corresponding to hydrides. The segmented images are converted into a finite element model by assigning node and element numbers together with corresponding material properties. Using the generated hydride cladding finite element model, several numerical methods are investigated to simulate crack propagation and cladding failure under pinch load. Using extended finite element (XFEM) models the initiation and propagation of a discrete crack along an arbitrary, solution-dependent path can be simulated without the requirement of remeshing. The applicability of fracture mechanical parameters such as stress intensity, J-integral was also investigated.

This study developed an analytical methodology for the mechanical integrity of spent nuclear fuel (SNF) cladding tubes under external pinch loads during transportation, with reference to the failure mode specified in the relevant guidelines. Special consideration was given to the degraded characteristics of SNF during dry storage, including oxide and hydride contents and orientations. The developed framework reflected a composite cladding model of elastic and plastic analysis approaches and correlation equations related to the mechanical parameters. The established models were employed for modeling the finite elements by coding their physical behaviors. A mechanical integrity evaluation of 14 × 14 PWR SNF was performed using this system. To ensure that the damage criteria met the applicable legal requirements, stress-strain analysis results were separated into elastic and plastic regions with the concept of strain energy, considering both normal and hypothetical accident conditions. Probabilistic procedures using Monte Carlo simulations and reliability evaluations were included. The evaluation results showed no probability of damage under the normal conditions, whereas there were small but considerably low probabilities under accident conditions. These results indicate that the proposed approach is a reliable predictor of SNF mechanical integrity.

In this study, the effect of slit length on the reduction of waste material was studied numerically. At the same time, the tightening axial force between steering shaft and asymmetry pinch yoke was also studied and compared. To achieve this study, the numerical simulation was performed by AFDEX commercial code. The slit length(Ls) of pinch yoke was increased from 25mm to 34mm by the steps with an interval of 3mm. AISI 1025 was applied for the source material of asymmetry pinch yoke. Amount of deformation was applied as much as 0.1mm for tightening the pinch bolt yoke and the steering gear shaft. It was revealed that the stress of steering shaft ear in XX-direction and YY-direction showed the highest value in 34mm and 31mm of slit length cases, respectively. The stress of ZZ-direction has the same value in all cases. The tightening stress between the asymmetry pinch yoke and the shaft of steering gear had the highest value in XY-direction. In additions, when slit length was increased by the steps with an interval of 3mm, the material was more wasted approximately as much as 0.844g. In conclusions, 31mm of lit length was the optimal length in aspect of the tightening stress and the waste material.

In this study, the effect of upper die type on the load characteristics of lower die and the wasted material was studied numerically. The different shapes(A-type, B-type, and C-type) of upper die were applied. Also finite element analysis method was applied for the analysis in each stage. The half of X, Y plane was analyzed due to the symmetrical shape in order to reduce the analysis time and be accurate results. The coefficient of friction was set to oil_cold conditions as refer to the system library. It was revealed that principal stress was the order in A, C, and B. A and B type have the highest value in 4 stage, and C type shows the highest value in 3 stage. In addition, Von mises stress were higher in order A, B, and C. A and B type have the highest in 4 stage, and C type shows to have about the same value in the 2 - 5 stage. The load was generally higher than C type. The load of C type was reduced in YY-direction at each stage without 2, 5, 6 stage.

In this study, the effect of upper die type on the load characteristics of lower die and the wasted material was studied numerically. The open and closed types of upper die were applied for each stage and the results are analyzed using a finite element analysis method. The half of x,y plane was analyzed due to the symmetrical shape in order to reduce the analysis time. The coefficient of friction was set to Soap_Cold conditions as refer to the analysis library. It was revealed that a lot of underfill portion was observed the open type in stage 4. As a result of the maximum and minimum values of the max principal stress, closed type case much receives compressive stress about 620MPa-2019MPa. In case of open type, The load was reduced in all direction at each stage

This paper carried out design in order to reduce the process of asymmetric pinch yoke, one of the important parts which transfer power to wheels through gearing box in automobile steering system. The purpose of the study is to reduce prime costs and strengthen competitiveness by designing the total 8 processes including the up-setting and forging process of the No. 1 as the forging process the current method of production. The process with die stress analysis by using the finite element method have been carried out through new optimal die design. As this study result, it is expected that die life can be secured as excellent material flow and caused by forming load. A prototype has been produced by basis of the analysis result and the reduction of the process was successful. As the unit price is lower than that of the current process, the competitiveness can be expected.

The aims of this study were to investigate the correlation between the electromyographic (EMG) activity of the abductor hallucis (AbdH) and the amount of pressure measured by a pinch gauge (PG), and to compare the EMG activity of AbdH and the pressure measured by the PG during short foot (SF) exercise in subjects with pes planus and in subjects with a neutral foot alignment. Fourteen subjects were recruited for this study (pes planus group=7; neutral foot alignment group=7). A surface EMG was used to collect AbdH activity, and a PG was positioned under the first metatarsophalangeal joint to measure the pressure produced by the first metatarsal head during the SF exercise. The AbdH activity and the pressure measured by the PG showed a positive good correlation (r=.80, p<.05). The EMG activity of the AbdH and the pressure measured by the PG were significantly lower for subjects with pes planus than for subjects with a neutral foot alignment (p<.05). Based on these findings, the PG can be recommended as an effective instrument for evaluating the performance of the AbdH. It may also be beneficial for monitoring how well the SF exercise is performed, and for providing visual feedback to patients with pes planus during SF exercise in a clinical setting.

In using both hands, everyone dominantly use one hand and it is called left-handedness or right-handedness person. Measurements of grip and pinch strength provide objective indexes to represent functional integrity of the upper extremity. This study was conducted for thirty female college students(19 right-handedness and 11 lefthandedness). For assessment of the type of handedness, questionnaire was used; for grip strength, Jamar dynamometer was used; for pinch strength, Jamar pinch gauge was used. In right handedness, the grip and pinch strength of the dominant right hand was significantly higher than those of the non-dominant hand. In addition, regular exercises were shown to give influences on reduction of strength gaps between dominant and non-dominant hands. In both groups of left and right handedness, the grip and pinch strength of the dominant hand were significantly higher than those of the non-dominant hand, and regular exercises were shown to give influences on reduction of strength gaps between dominant and non-dominant hand.

The purpose of this study was to determine the difference of the pinch strength according to testing posture(standing and sitting) and elbow flexion degree(0。, 45。, 90。and 135。). Forty normal young adults(male: 20, female: 20, mean age: 22.68±2.91 years) participated in this study. The methods of this study were categorized as follows: 1) One set of measurement was performed on four elbow flexion degrees(0。, 45。, 90。and 135。) in two testing postures(standing and sitting) and all subjects were measured for 3 sets testing procedures in every experimental sessions. 2) Pinch strength in various elbow flexion degree was measured after 2 min rest time, and then each test set was repeatedly performed with 5 min rest time to prevent fatigue of muscles involved in the elbow joint. The result was obtained as follow: 1) In standing posture, there was statistically significant difference at 0。and 45。, 0。and 90。, 0。and 135。, 45。and 90。, 45。and 135。, 90。and 135。. 2) In sitting posture, there was statistically significant difference at 0。and 45。, 0。and 90。, 0。and 135。, 45。and 90。, 45。and 135。, 90。and 135。. 3) Statistically, there was no significant difference between standing and sitting posture in same elbow flexion degree, however pinch strength in standing posture was higher than sitting posture.

The LNG carriers have been propelled by steam turbines and the LNG boil-off(BOG) has been used as fuel or vented. However, as the alternative propulsion systems such as diesel engines are being equipped on the LNG carriers for better fuel efficiency, a need for the LNG BOG re-liquefaction system that liquefies the BOG and sends the liquid BOG back to the LNG cargo has arisen in recent years. This study investigates the design of the BOG re-liquefaction system based on the reverse Brayton refrigeration cycle. The thermodynamic and heat exchanger analysis are carried out and the limitations to the system performance are discussed.

The purpose of this study is to find the standard value of hand width, of grip strength and of pinch strength by age, sex, and by left hand and right hand and also to find how the general characteristics influences grip strength and pinch strength. Martin Vigorimeter (List No. 17-27-01) was used for measuring grip strength, and the pinch gauge (0∼30 lbs) of B&L engineering for measuring pinch strength. The subjects of this study are the children at the age of three to seven years, who attending the babies' play room, kindergarten and the primary school in Seoul and the Kyungki province area. They all were normally developed without any significant neurology problem. wo hundred girls and two hundred boys were partifipated in this study. They were divided into ten subgroups according to the age of six month interval. Each group consisted of forty children of twenty boys and twenty girls. Analysis of data presents the technical statistics upon the hand width of right and left hand and the grip strength and pinch strength according to the age and sex. Multiple regression analysis using mixed liner model was operated in order to find how the general characteristics (of the age, sex, and side of hand) influence hand width, grip strength, and pinch strength individually. Also, we calculated the correlation among hand width, grip strength and pinch strength under the condition of controlling general characteristics; and to find correlation between the right hand and the left hand of the age and sex, we carried out paired t-test and came to the conclusion as follows: 1.　Hand width is significantly increased with the increase of age (p<0.01). The increase of hand width according to age, boy is wider than that of girl significantly (p<0.01), and the right hand is wider than that of the left hand significantly (p<0.01). 2.　Grip strength is significantly increased as the age and hand width increased (p<0.01). The increase of grip strength according to the age, boy is stronger than that of girl significantly (p<0.01), and grip strength of the right hand is stronger than that of the left hand(p<0.01). 3.　Three-jaw pinch strength is increased as the age, hand width and grip strength are increased(p<0.01). But there is no significant difference of three-jaw pinch strength according to sex and the side of hand(p>0.05). 4.　Tip pinch strength is significantly increased as the age and grip strength are increased(p<0.05). The increase of tip pinch strength according to the age, boy is stronger than that of girl significantly (p<0.05), but there is no significant difference between the right hand and the left hand(p>0.05). 5.　Lateral pinch strength is significantly increased as the age and grip strength are increased(p<0.01). But the increase of lateral pinch strength, there is no significant difference according to the hand width, sex and the side of hand(p>0.05). 6.　The test of correlation among hand width, grip strength and pinch strength showed the correlation between grip strength and pinch strength was stronger than the correlation between hand width and pinch strength(0.3<r<0.7). There was strong correlation between each pinch strength(0.3<r<0.7). Above all, the correlation of three-jaw pinch strength and tip pinch strength was strongest(0.7<r<1.0). 7.　The test of hand width according to the age and sex, and the difference between the right hand and the left hand in grip strength and pinch strength showed that there was significant difference against all the test of hand width, of grip strength, and of pinch strength in the age group from seven years and six months to seven years and eleven months than the age group under six years, specially in girls group(p<0.05).