Earticle

The human body has many degrees of freedom (1-3 degrees of freedom) per joint, enabling smooth and stable walking. However, unlike humans, robots require many more joints, and their design necessitates the control of numerous motors. However, controlling more motors leads to lower walking stability. Therefore, this paper studies a real-time control method for stable walking of a bipedal robot. To enable stable walking of a bipedal robot with 12 degrees of freedom, we study a method for generating and supplementing walking patterns between each joint using numerical analysis of the multi-joint robot's kinematics and learning-based AI. This research is to apply the adaptive control of neuron networks for the real-time attitude control of Multi-articulated robot. Multi-articulated robot is expressed with a complicated mathematical model on account of the mechanic, electric non-linearity which each articulation of mechanism has, and includes an unstable factor in time of attitude control. If such a complex expression is included in control operation, it leads to the disadvantage that operation time is lengthened. Thus, if the rapid change of the load or the disturbance is given, it is difficult to fulfill the control of desired performance. In this research we used the response property curve of the robot instead of the activation function of neural network algorithms, so the adaptive control system of neural networks constructed without the information of modeling can perform a real-time control. The proposed adaptive control algorithm generated control signs corresponding to the non-linearity of Multi-articulated robot, which could generate desired motion in real time.

알루미늄합금 6061-T6 판재에 대하여 마찰교반용접과 텅스텐 이너트 가스 용접의 교차 용접부의 미세조직과 기계적 특성에 있어서 용접 순서의 영향을 분석하기 위한 시험편을 성공적으로 제작하였다. FSW-ED 시험편이 다른 조합들보다 가장 좋은 기계적 특성을 나타내었다. 흥미롭게도, TIG-FSW ED 시험편이 FSW-TIG ED 시험편보다 높은 인장강도를 나타내었다. 용접부 경도의 경우, FSW 시편이 TIG-FSW 및 FSW-TIG 시험편보다 높은 값을 나타내었고, TIG-FSW 시험편이 FSW-TIG 시험편보다 높은 값을 나타내었다. FE-SEM을 이용한 인장 파면에 대한 관찰을 통하여, 모든 시험편에서 연성파괴를 나타내는 다양한 크기의 딤플들이 관찰되었다. FSW-TIG 시험편의 파면에서는 용융지(熔融池) 표면 영역에서 기공들이 관찰되는 반면, TIG-FSW 시험편에서는 기공의 형성은 관찰되지 않았다. 경도와 미세조직의 결과를 통해 TIG-FSW 공정이 FSW-TIG 공정보다 높은 인장강도를 확보할 수 있는 공정임을 확인하였다.

The cross-welded joints for 6061-T6 aluminum alloy sheets were successfully manufactured through friction stir welding(FSW) and tungsten inert gas(TIG) welding methods to reveal the effect of welding sequence on microstructure and mechanical properties of the joints. Results revealed that FSW-ED joint shows maximum joint strength compare to other combinations. Interestingly, TIG-FSW joint shows much higher tensile strength than FSW-TIG joint. It is seen that the average hardness in SZ of friction-stir-welded specimen is comparatively higher than that of TIG-FSW and FSW-TIG joints. TIG-FSW specimen also shows higher hardness compare to FSW-TIG. Through FE-SEM observation for tensile fracture surface, various size of dimples clearly observed indicating ductile type of failure mode in all specimens. In case of FSW-TIG process, several voids were observed at the surface region of weld pool. On the contrary, no as such void formation has been observed in TIG-FSW process. The micro hardness and microstructural results clearly justify the higher tensile strength in TIG-FSW process.

In this study, we intend to develop a control valve with oxidation resistance for hydrogen fluoride that can be applied to the semiconductor production process. Operated Valves currently in use is a form of assembling an air cylinder to the valve body. These valves generally have a cylinder body made of aluminum (Al), so they may corrode depending on the external environment, and the solution leaks along the rod inside the cylinder, causing damage to parts due to corrosion. To solve this problem, the valve plug shape was developed by devising and applying a plug using a valve different from the existing method, and it is possible to block the inflow of hydrogen fluoride into the valve control unit, thereby preventing damage to parts as well as maintaining stable valve operation.

This study analyzed the methods and characteristics of hydrogen production, storage, transportation, charging, and use of hydrogen presented as an energy supply and demand system for hydrogen. Hydrogen produced by reforming hydrogen, which exists in the form of compounds, is essential to use metal materials exposed to the hydrogen atmosphere in storage and transportation. The mechanism of hydrogen embrittlement and damage cases, which are phenomena in which hydrogen atoms penetrate into the crystal lattice of metal and cause crack failure, were investigated. In addition, it is intended to present a research direction related to the evaluation of physical properties such as thermal conductivity, thermal expansion coefficient, and heat capacity, which are the criteria for selecting materials for hydrogen in a cryogenic environment.

This study is based on the screen printing method with heat resistant thin film as base material and development for expansion is proceeding. Therefore, it is convenient to be applicable to the installation and it will be possible to reduce the cost compared with the existing construction such as heat trace by 50% or more. As a result, it is possible to develop and commercialize the market for Polar ship, shipbuilding and offshore plants as it is possible to secure CNT(Carbon Nano Tube) based surface heating element and heating paste composition technology as a heating element material at a cryogenic temperature. It is expected that the efficiency will be great when this method is applied to other industries.

In order to reduce environmental pollution, it is necessary to increase the recycling rate of waste. For this, the separation of recyclables is of utmost importance. The paper conducted a study to automatically discriminate containers by material for beverage containers among recyclables. We developed an algorithm that automatically recognizes containers by four materials: metal, glass, plastic, and paper by measuring the vibration signal generated when the beverage container collides with the bottom plate of the collection box. The amplitude distribution, time series information, and frequency information of the vibration signal were used to extract the characteristics indicating the characteristic difference of the vibration signal for each material, and a classifier was developed through machine learning using these characteristics.

Unlike wheeled vehicles, tracked armored vehicles require a highly developed transmission technology since the transmission has to not only shift gears but also steer and brake the heavy ground weapon system precisely. Even though weapons systems including the K00 Infantry Fighting Vehicle (IFV) have recently been developed with domestic technology, it is true that many core parts in the systems are still being imported. In this paper localization process of the accumulator which is one of the most important hydraulic parts in the K00 transmission is introduced. In order to determine design variables such as operating pressure we analyzed torque characteristics of the transmission and calculated spring constant by disassembling the original accumulator. And tests such as durability, safety, etc. were conducted to assure the validation of the development. We expect that the process of reverse engineering we adopted will be helpful to localize similar hydraulic parts.

This paper studied a new shape unit model based on Gibson and Ashby's theory. As a result of theoretical research, the relative density equation is correlated with relative elasticity, and through this study, the theoretical relationship between the relative elasticity equation was defined. The relative elasticity equation was defined based on the model for which the analysis was performed. According to the analysis results, the diameter of the model was set to 3 mm, and the maximum stress values ​​were confirmed by reflecting the same boundary conditions. The maximum stress for each model is 5668.9MPa for Type 1, 5136.7MPa for Type 2, 5642MPa for Type 3, and 6032.9MPa for Type 4 when the truss diameter is 3mm. The relative elasticity equation was defined based on this condition. In the future, compression analysis will have to be performed in the same way, reflecting the diameter of the truss at 5 mm and 7 mm, to find and define the coefficients of the relative elasticity equation, and verification through experiments will have to be carried out based on the theoretical equation. In addition, in order to be applied in each field, proof through prototype production and installation must be carried out.

In this study, SM45C-STKM13B hollow shaft of different thickness was joined by friction welding. After friction welding, we treated to specimen of annealing(post-weld heat treatment). The specimens were tested as-welded and post-weld heat treatment(PWHT). The mechanical properties including tensile test and vickers micro-hardness were examined. And then, the mechanical properties were compared for as-welded and PWHT in SM45C to STKM13B. Microstructure of joining part were examined in the weld interface and weld region and heat affected zone and base metal of weld parts.

In this study, we attempted to examine how the management commitment and safety communication affect the safety behavior of flight crew members while performing their duties. In addition, we attempted to examine how the individual cultural values ​​of each flight crew are involved and influenced in such influence relationships. As a result of the study, among the sub-variables of safety behavior, the relationship between commitment to safety compliance and communication was found to have no statistically significant effect (∆R2 = .049, p = .5), and the relationship between commitment to safety participation and communication was found to had a statistically significant effect (∆R2 = .088, p < .001). As a result of examining the moderating effect of individual culture values ​​in the relationship between commitment to safety participation and communication, the moderating effect of uncertainty avoidance (β = .256, p < .05) showed statistically significant results, and management's commitment/communication The interaction effect between and uncertainty avoidance had a statistically significant effect when uncertainty avoidance was low, but was not statistically significant when uncertainty avoidance was high.