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.

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.

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 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.

반도체 직접회로 패키지에서, 실리콘 칩의 탑 표면은 양면 리드 프레임 영역에서 바로 붙게 된다. 여기서, 양면이란 베이스 층에 상위 접착층과 하위 접착층으로 되어 있음을 말한다. IC 패키지 구조는 탈 라미네이트 화와 같이 열-기계적 파손 모드로 나타나게 된다고 알려져 왔다. 이 파손 모드의 원인은 실리콘 칩 접착면의 잔류응력 과 냉간 숙성 공정 내에 리드 프레임으로 인해 일어난다. 숙성 공정 내 유도된 열응력은 실리콘 칩과 리드 프레임위에 냉간 잔류 응력에 영향을 가진다. 본 연구에서는 칩 표면 손상의 최소화를 위해서, 실리콘 칩 위에 접착 위상 최적화 방법들이 유한 요소 해석(Finite Element Analysis)을 통해 연구되었다

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.

Recently, 3D printing has been actively studied. A representative material in this 3D printing technology is plastic, and PLA, an eco-friendly material, is widely used. FDM is widely used as a way to output these PLA materials. However, this method lacks mechanical properties compared to injection-molded products as it is a method of stacking materials by melting. Therefore, in this study, using an FDM-type 3D printer, a tensile test was performed after printing a tensile specimen with PLA filament with the layer angle and layer density as control factors. After that, changes in tensile properties according to the layer angle and density were compared and evaluated. As a result, to improve the tensile strength, the layer density had to be considered, and to improve the elastic modulus, both the layer angle and the layer density had to be considered.