This study analyzed the influence of ball size and process control agents on the refinement and dehydrogenation behavior of TiH2 powder. Powders milled using ZrO2 balls with diameters of 0.1 mm, 0.3 mm, and 0.3+0.5+1 mm exhibited a bimodal particle size distribution, of which the first mode had the smallest size of 0.23 μm for the 0.3 mm balls. Using ethanol and/or stearic acid as process control agents was effective in particle refinement. Thermogravimetric analysis showed that dehydrogenation of the milled powder started at a relatively low temperature compared to the raw powder, which is interpreted to have resulted from a decrease in particle size and an increase in defects. The dehydrogenation kinetics of the TiH2 powder were evaluated by the magnitude of peak shift with heating rates using thermogravimetric analysis. The activation energy of the dehydrogenation reaction, calculated from the slope of the Kissinger plot, was measured to be 228.6 kJ/mol for the raw powder and 194.5 kJ/mol for the milled powder. TEM analysis revealed that both the milled and dehydrogenated powders showed an angular shape with a size of about 200 nm.

The structure and magnetic properties of composite powders prepared by ball milling a mixture of Fe2O3 ‧ (0.4-1.0)Fe were investigated. Hysteresis loops and differential scanning calorimetry (DSC) curves are used to characterize the materials and to examine the effect of the solid state reaction induced by ball milling. The results showed that a solid state reaction in Fe2O3 ‧ (0.4-1.0)Fe clearly proceeds after only 1 h of ball milling. The system is characterized by a positive reaction heat of +2.23 kcal/mole. The diffraction lines related to Fe2O3 and Fe disappeared after 1 h of ball milling and, instead, diffraction lines of the intermediate phase of Fe3O4 plus FeO formed. The magnetization and coercivity of the Fe2O3 ‧ 0.8Fe powders were changed by the solid state reaction process of Fe2O3 by Fe during ball milling. The coercivity of the Fe2O3 ‧ 0.8Fe powders increased with increasing milling time and reached a maximum value of 340 Oe after 5 h of ball milling. This indicates the grain size of Fe3O4 was clearly reduced during ball milling. The magnetic properties of the annealed powders depend on the amount of magnetic Fe and Fe3O4 phases.

This study investigated the effects of revolution speed and ball size in planetary milling on the microstructure and dehydrogenation behavior of TiH2 powder. The particle size analysis showed that the large particles present in the raw powder were effectively refined as the revolution speed increased, and when milled at 500 rpm, the median particle size was 1.47 μm. Milling with a mixture of balls of two or three sizes was more effective in refining the raw powder than milling with balls of a single size. A mixture of 3 mm and 5 mm diameter balls was the optimal condition for particle refinement, and the measured median particle size was 0.71 μm. The dependence of particle size on revolution speed and ball size was explained by changes in input energy and the number of contact points of the balls. In the milled powder, the endothermic peak measured using differential thermal analysis was observed at a relatively low temperature. This finding was interpreted as the activation of a dehydrogenation reaction, mainly due to the increase in the specific surface area and the concentration of lattice defects.

본 논문의 목적은 딴뜨라 요가 전통에서 소리의 의미를 고찰하고, 상캬 다섯 요소의 관점에서 싱 잉볼이 갖는 치유적 의미를 통해 요가 수련에서의 활용법을 제시하는 데 있다. 딴뜨라 요가에서 소리 는 보다 근원적인 진동의 에너지로 자기실현과 영적 성장을 위한 도구로 간주 되어 수련에 적용되어 왔다. 다양한 주파수를 가진 싱잉볼의 진동 또한 파동에너지로 뇌파와 동기화하여 빠른 이완을 유도 하고 에너지장을 조율하며 궁극적으로 심신의 치유를 이끌어 낸다. 싱잉볼의 소리와 진동은 상캬의 25원리(tattva) 중 성(聲) 미세 요소, 공(空) 거친 요소와 관련된다. 이는 다섯 요소 중 가장 미세한 것 으로 마음과 가장 가까이 위치하며 밀접한 영향을 주고 받는다. 또한 성과 공은 누적 전변되는 과정 에서 다른 요소들에 포함된다. 따라서 싱잉볼을 이용한 소리 치유는 가장 미세하면서도 물질의 모든 요소를 아우르는 보편적인 치유법이라 할 수 있으며, 이는 싱잉볼이 물질과 에너지로 이루어진 몸의 차원을 넘어 마음과 영혼에 작용하는 기전을 설명하는 것으로 이해할 수 있다. 요가 수련 또한 다섯 거친 요소로 이루어진 몸의 차원에서 보다 미세한 마음의 차원으로 정화해 가는 과정이며 이 과정에 서 싱잉볼의 소리는 집중의 대상으로, 진동은 이완을 완전하게 하는 요소로 요가 수련에 통합할 수 있다.

이 연구는 지속적인 싱잉볼 힐링이 뇌파와 자율신경계 반응에 어떠한 영향을 미치는지를 알아보기 위한 연구이 다. 5주 동안 8명의 피실험자에게 싱잉볼 힐링을 받은 전,후 뇌파의 변화를 알아보기 위하여, 45분 동안의 싱잉볼 힐링 받기 전, 후 뇌파의 변화를 측정하였다. 뇌파측정은 바이오브레인 BIOS-S8로의 F3, F4, T3, T4, P3, P4 총 6체널에 부착하였고, 심전도 측정을 위하여 표준사지 유도방식에 Lead I에 전극을 부착하여 측정하였다. 수집된 뇌파자료를 통하여 5주간의 싱잉볼 힐링 전,후 뇌파의 변화를 지켜보았으며, 베타파, 알파파, SMR는 낮아지고, 세 타와 델타파, HRV 항목 중 SDNN이 증가시키는 것으로 나타났다. 이 결과 5주 동안의 지속적인 싱잉볼 힐링은 뇌파를 안정시키고, 자율신경계를 활성화 시키며, 부교감신경을 증가시키는 이완유도 효과를 지속, 증대 시킬 수 있다는 점을 확인하였다.

Recently, in the case of the root industry, although it is a basic industry that forms the basis of manufacturing competitiveness, there continues to be a shortage of manpower due to reasons such as dangerous working environments, industrial economic difficulties, and low wage systems. In addition, the demand for automation of production lines using robots is increasing due to a shrinking labor market due to a decrease in the working population due to aging, higher wages, shorter working hours, and limitations of foreign workers. In this study, a system was developed to automate the injection molding process for producing ball valves for automobiles by applying robot system. The applied process flow consists of alignment and insertion of insert parts, and removal, transfer, and loading of the product after injection molding, which is currently performed manually. Through the application of the developed robot automation system, the cycle time was improved by more than 30% and the defect rate was reduced by more than 70%.

수경 재배한 멜론의 생육과 수확 후 모의유통 시 품질 차이를 검토하였다. ‘루비볼춘추계’의 수경재배 된 멜론을 이용하여 저장 온도를 2℃와 5℃, 10℃, 20℃하여 모의유통 시 특성과 가용성고형물(SSC), 경도, 생체중 변화, 외관 등의 변화를 조사하였다. 멜론을 상온으로 유통하는 조건 하에서 저온저장에 따른 과실 특성을 본 연구에서 확인하였다. 멜론 저장 시 가용성고형물, 경도, 생체중, 외관이 저장온도에 따라 차이를 보였다. 가용성고형물은 멜론을 저온(2~5℃)에서 저장하여 모의유통 된 것이 상온(20℃)에서 다른 온도처리보다 높은 수준인 것으로 나타났다. 외관과 경도는 모의유통 중 저장 온도에 따른 영향이 지속적이지는 못하였지만 유통초기 저온(2~10℃) 저장이 외관 지수 및 경도 수치가 높은 경향이었다. 저장 온도에 따른 영향이 모의유통 시 계속 효과를 유지하지 못하여 국내 유통 시 이를 고려하여야 할 것이다. 본 연구 결과, 저장 온도에 따른 모의유통 중에 미치는 영향은 저장 직후 짧은 단기간에만 효과를 유지하여, 국내 유통 하에서 저장할 경우에는 바로 소비할 수 있도록 유도해야 할 것으로 생각된다.

Ball stud parts are manufactured by a cold forging process, and fastening with other parts is secured through a head part cutting process. In order to improve process quality, stabilization of the forging quality of the head is given priority. To this end, in this study, a predictive model was developed for the purpose of improving forging quality. The prediction accuracy of the model based on 450 data sets acquired from the manufacturing site was low. As a result of gradually multiplying the data set based on FE simulation, it was expected that it would be possible to develop a predictive model with an accuracy of about 95%. It is essential to build automated labeling of forging load and dimensional data at manufacturing sites, and to apply a refinement algorithm for filtering data sets. Finally, in order to optimize the ball stud manufacturing process, it is necessary to develop a quality prediction model linked to the forging and cutting processes.

Tungsten disulfide (WS2) nanosheets have attracted considerable attention because of their unique optical and electrical properties. Several methods for fabrication of WS2 nanosheets have been developed. However, methods for mass production of high-quality WS2 nanosheets remain challenging. In this study, WS2 nanosheets were fabricated using mechano-chemical ball milling based on the synergetic effects of chemical intercalation and mechanical exfoliation. The ball-milling time was set as a variable for the optimized fabricating process of WS2 nanosheets. Under the optimized conditions, the WS2 nanosheets had lateral sizes of 500–600 nm with either a monolayer or bilayer. They also exhibited high crystallinity in the 2H semiconducting phase. Thus, the proposed method can be applied to the exfoliation of other transition metal dichalcogenides using suitable chemical intercalants. It can also be used with highperformance WS2-based photodiodes and transistors used in practical semiconductor applications.

In this study, 3D design, vibration analysis and experiment, and feed rate performance test were performed to develop a vibratory bowl feeder for supplying ultra-thin plate parts of less than 50 microns. The natural frequency and resonant frequency of the vibratory bowl feeder were obtained through the vibration analysis and experiment, and it was confirmed that the results of the analysis and experiment agree well. Through the feed rate experiment, it was confirmed that up to 610 ultra-thin parts per minute were fed at 250Hz and a supply voltage of 220V, where the excitation frequency and the resonant frequency match. And through analysis and experimental research, it was confirmed that the development of a vibratory bowl feeder for supplying ultra-thin parts was successful.

Most of automobile steering parts are manufactured through the multi-stage cold forging process using round-bar drawn materials. The same process is applied to the ball stud parts of the outer ball joint, and various research activities are being carried out to reduce the extreme manufacturing cost in order to survive in the limitless competition. In this paper, we present a quantitative prediction method for the limiting life of the die as a method for cost reduction in the multi-stage cold forging process. The load on the die was minimized by distributing the forming load based on process optimization through finite element analysis. In addition, based on the quantitative prediction algorithm of the limiting life of the die, the application of the split die and the optimization of the phosphate treatment of the material surface are presented as a conclusion as a method to improve the limiting life of the die.

Recently, high-entropy carbides have attracted considerable attention owing to their excellent physical and chemical properties such as high hardness, fracture toughness, and conductivity. However, as an emerging class of novel materials, the synthesis methods, performance, and applications of high-entropy carbides have ample scope for further development. In this study, equiatomic (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide powders have been prepared by an ultrahigh- energy ball-milling (UHEBM) process with different milling times (1, 5, 15, 30, and 60 min). Further, their refinement behavior and high-entropy synthesis potential have been investigated. With an increase in the milling time, the particle size rapidly reduces (under sub-micrometer size) and homogeneous mixing of the prepared powder is observed. The distortions in the crystal lattice, which occur as a result of the refinement process and the multicomponent effect, are found to improve the sintering, thereby notably enhancing the formation of a single-phase solid solution (high-entropy). Herein, we present a procedure for the bulk synthesis of highly pure, dense, and uniform FCC single-phase (Fm3m crystal structure) (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide using a milling time of 60 min and a sintering temperature of 1,600oC.

Background: Muscle activities of gluteus maximus (GM) and hamstring (HAM) have important roles in the stability and mobility of the hip joint during various functional activities including bridge and prone hip extension exercises. Objects: The purpose of this study is to investigate muscle activities of GM, multifidus (MF) and HAM during three different bridge exercises in healthy individuals. Methods: Twenty healthy subjects were participated. Electromyography device was used to measure muscle activities of GM, MF and HAM. Each subject was asked to perform three different bridge exercises with hip abduction (0°, 15°, 30°) in random order. One-way repeated measures analysis of the variance and a Bonferroni post hoc test were used. Statistical significance was set at α = 0.01. Results: The muscle activity of GM was significantly different among three conditions (hip abduction 0°, 15°, 30°) (adjusted p-value [Padj] < 0.01). The muscle activity of GM was significantly greater during bridge exercise with hip abduction 30° compared to 0° and 15° (Padj < 0.01). There was no significant difference in the muscle activity of MF and HAM muscle (Padj > 0.01). The ratio of muscle activity (ratio = GM/HAM) during bridge exercise with hip abduction 30° was significant greater compared to the hip abduction angles 0° and 15° (Padj < 0.01). Conclusion: Bridge exercise with hip abduction 30° can be recommended to selectively facilitate the muscle activity of GM and improve the ratio of muscle activity between GM and HAM.

Tin/graphite composites are prepared as anode materials for Li-ion batteries using a dry ball-milling process. The main experimental variables in this work are the ball milling time (0–8 h) and composition ratio (tin:graphite=5:95, 15:85, and 30:70 w/w) of graphite and tin powder. For comparison, a tin/graphite composite is prepared using wet ball milling. The morphology and structure of the different tin/graphite composites are investigated using X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and scanning and transmission electron microscopy. The electrochemical properties of the samples are also examined. The optimal dry ball milling time for the uniform mixing of graphite and tin is 6 h in a graphite-30wt.%Sn sample. The electrode prepared from the composite that is dry-ballmilled for 6 h exhibits the best cycle performance (discharge capacity after 50th cycle: 308 mAh/g and capacity retention: 46%). The discharge capacity after the 50th cycle is approximately 112 mAh/g, higher than that when the electrode is composed of only graphite (196 mAh/g after 50th cycle). This result indicates that it is possible to manufacture a tin/graphite composite anode material that can effectively buffer the volume change that occurs during cycling, even using a simple dry ball-milling process.

포인세티아(Euphorbia pulcherrima. Willd. Ex Klotzch) ‘Red Ball’은 국립원예특작과학원에서 2019년에 육성한 품종이다. ‘Red Ball’은 긴 관상 기간을 가지는 ‘Christmas Eve’를 모본으로 빨간색 주름진 덮개잎이 볼 타입 꽃을 만드는 ‘Winter Rose Early Red’를 부본으로 교배하여 획득한 실생 계통을 선발하여 육성하였다. 2016년부터 2018년 생육, 개화, 균일성 등에 대하여 1,2차 특성 검정을 실시하였다. 이후 2019년 3차 특성검정을 실시하여 최종선발한 후 직무육성품종심의회에 상정하여 ‘Red Ball’로 명명하였다. ‘Red Ball’품종은 전체적으로 짧은 적색 덮개잎을 가지며 꽃 모양이 납작하지 않아 입체감이 높다. 또한 단일 처리후 약 5.5~6주가 경과하면 완전히 착색되어 출하가 가능할 만큼 착색소요기간이 짧다. ‘Red Ball’은 2021년 4월 12일에 국립종자원에 품종등록(제8497호) 되었다.