Research has been conducted on a wide variety of 3D printer circular fin heads. In this study, we proposed a sequence and method for a more efficient mesh study in the CFD model to calculate the Nusselt number of the circular fin head of an FDM 3D printer using the Taguchi method, sensitivity, and ANOVA. As a result, the CFD model to calculate the Nusselt number of the circular fin head of an FDM 3D printer has high sensitivity and contribution in the order of Base target mesh size, Prism layer number, and Prism layer thickness. We propose to increase work efficiency by performing mesh optimization in the order of factors with high sensitivity to level changes.

Recently 3d printer industry has two demands. first is color 3d printing. second is mass production using 3d printer that has large bed. According to previous studies, 3D printed objects have different weights depending on filament colors. 3D printed tensile specimens with filaments of various colors were checked to see they had the same weight. If so, we wanted to see it was statistically significant. As a result, we found that the weight of 3D printed objects was statistically significantly different depending on the filament color. The average weight of 3d printed objects is: Black(8.63g), Blue(8.58g), Yellow(8.53g), White(8.48g), Natural(8.46g), Green (8.45g), Red(8.42g).

Ppuri or Root technology primarily includes technologies such as casting, mold, plastic working, welding, heat treatment and surface treatment. It is regarded as an essential element for improving the competitiveness of the quality of final products. This study investigates the current status of smart factory implementation for Ppuri companies and analyzes the influencing relationships among various company factors. The factors affecting smart factory implementation for Ppuri companies are sales, exports, number of technical employees, and holding corporate research institutes. In addition, this research shows that even if smart factory implementation is pursued for data collection, data utilization is not implemented properly. Thus, it is suggested that the implementation of smart factories requires not only the availability of facilities and systems but also proper data utilization.

Rare earth elements, which are important components of motors, are in high demand and thus constantly get more expensive. This tendency is driven by the growth of the electric vehicle market, as well as environmental issues associated with rare-earth metal manufacturing. TC 298 of the ISO manages standardization in the areas of rare-earth recycling, measurement, and sustainability. Korea, a resource-poor country, is working on international standardization projects that focus on recycling and encouraging the domestic adoption of international standards. ITU-T has previously issued recommendations regarding the recycling of rare-earth metals from e-waste. ISO TC 298 expands on the previous recommendations and standards for promoting the recycling industry. Recycling-related rare earth standards and drafts covered by ISO TC 298, as well as Korea’s strategies, are reviewed and discussed in this article.

A well-established characterization method is required in powder bed fusion (PBF) metal additive manufacturing, where metal powder is used. The characterization methods from the traditional powder metallurgy process are still being used. However, it is necessary to develop advanced methods of property evaluation with the advances in additive manufacturing technology. In this article, the characterization methods of powders for metal PBF are reviewed, and the recent research trends are introduced. Standardization status and specifications for metal powder for the PBF process which published by the ISO, ASTM, and MPIF are also covered. The establishment of powder characterization methods are expected to contribute to the metal powder industry and the advancement of additive manufacturing technology through the creation of related databases.

SiC is a material with excellent strength, heat resistance, and corrosion resistance. It is generally used as a material for SiC invertors, semiconductor susceptors, edge rings, MOCVD susceptors, and mechanical bearings. Recently, SiC single crystals for LED are expected to be a new market application. In addition, SiC is also used as a heating element applied directly to electrical energy. Research in this study has focused on the manufacture of heating elements that can raise the temperature in a short time by irradiating SiC-I2 with microwaves with polarization difference, instead of applying electric energy directly to increase the convenience and efficiency. In this experiment, Polydimethylsilane (PDMS) with 1,2 wt% of iodine is synthesized under high temperature and pressure using an autoclave. The synthesized Polycarbosilane (PCS) is heat treated in an argon gas atmosphere after curing process. The experimental results obtain resonance peaks using FT-IR and UV-Visible, and the crystal structure is measured by XRD. Also, the heat-generating characteristics are determined in the frequency band of 2.45 GHz after heat treatment in an air atmosphere furnace.

Powder characteristics, such as density, size, shape, thermal properties, and surface area, are of significant importance in the powder bed fusion (PBF) process. The powder required is exclusive for an efficient PBF process. In this study, the particle size distribution suitable for the powder bed fusion process was derived by modeling the PBF product using simulation software (GeoDict). The modeling was carried out by layering sintered powder with a large particle size distribution, with 50 μm being the largest particle size. The results of the simulation showed that the porosity decreased when the mean particle size of the powder was reduced or the standard deviation increased. The particle size distribution of prepared titanium powder by the atomization process was also studied. This study is expected to offer direction for studies related to powder production for additive manufacturing.

Background: Visual and somatosensory integration processing is needed to reduce pusher behavior (PB) and improve postural control in hemiplegic patients with acute stroke. Objects: This study aimed to investigate the effects of game-based postural vertical training (GPVT) on PB, postural control, and activity daily living (ADL) in acute stroke patients. Methods: Fourteen participants with acute stroke (<2 months post-stroke) who had PB according to the Burke lateropulsion scale (BLS) (score>2) were randomly divided into the GPVT group (n1=7) and conventional postural vertical training (CPVT) group (n2=7). The GPVT group performed game-based postural vertical training using a whole-body tilt apparatus. while the CPVT group performed conventional postural vertical training to reduce PB (30 minutes/session, 2 times/day, 5 days/week for 3 consecutive weeks). The BLS was evaluated to assess the severity of PB. And each subject’s postural control ability and ADL level were assessed using the postural assessment scale for stroke (PASS), balance posture ratio (BPR), and Korean-modified Barthel index (K-MBI). Outcomes were measured preand post-intervention. Results: Comparison of the pre- and post-intervention assessment results showed that both interventions led to the following significant changes: decreased severity of PB scores and increased PASS, BPR, and K-MBI scores (p<.05). In particular, statistical analysis between the two groups, the BLS score was significantly decreased in the GPVT group (p<.05). And PASS, BPR, and K-MBI scores were significantly improved in the GPVT group than in the CPVT group (p<.01, respectively). Conclusion: This study demonstrated that GPVT lessened PB severity and improved postural control ability and ADL levels in acute stroke patients.

Since the ISO decided to deal with rare-earth elements at the 298th Technical Committee (TC) in 2015, Korea has participated in four plenary meetings and proposed four standards as of June 2019. The status of ISO TC 298, the standards covered by the TC, and the standardization strategies of Korea are summarized. Korean delegations are actively engaged in WG2, which deals with recycling, proposing four standards for fostering the rare-earth recycling industry. However, the participation of domestic experts is still low compared with the increase in the number of working groups and the number of standards in TC 298. The aim of this article is to summarize the current status of ISO international standards related to rare-earth elements, to encourage relevant experts to participate in standardization, and to develop international standards that accurately reflect the realities of the industry.

Background: Genu varum is also known as bow leg. It is a deformity wherein there is lateral bowing of the legs at the knee. it does give rise to pain, and persistent bowing can often give rise to discomfort in knees, hips and ankles. Objects: This study investigated the effect of narrow squats on the knee joint during a gait and distance between the knees of person with genu varum. Methods: This study analyzed 23 patient with genu varum that grade Ⅲ, 12 narrow squat group and 11 genenal squat group in motion analysis laboratory. The subjects of experiment took gait before and after intervention, the range of joint motion, moment of knee joint adduction, power, distance of the knees were measured. And in order to make an analysis between groups, an paiered t-test and independent t-test was carried out. For statistical significance testing, it was decided that significance level α be .05. Results: It was shown that the group of narrow squat exercise significantly decreased in distance of knees (p<.05),In moment of adduction of knee joint, it was shown to significantly decrease in two groups (p<.05), was significantly decreased in adduction, abduction, and rotation (p<.05). In relation of peak-knee adduction moment and valgus angle, there was significant decrease in narrow squat group (p<.05). Conclusion: When the above result of study were examined, a narrow squat exercise given to the genu varum patients significantly decreased the distance between the knees, range of knee adduction and abduction, knee adduction moment, knee power. And stability gains through the decrease of excursion of knee medial part be effective for the correction of genu varum deformation.

Background: It is very difficult for hemiplegic patients to effectively perform the sit-to-stand (STS) movements independently because of several factors. Moreover, the analysis of STS motion in hemiplegic patients has been thus far confined to only muscle strength evaluation with little information available on structural and environmental factors of varying chair height and foot conditions. Objects: This study aimed to analyze the change in biomechanical factors (ground reaction force, center of mass displacement, and the angle and moment of joints) of the joints in the lower extremities with varying chair height and foot conditions in hemiplegic patients while they performed the STS movements. Methods: Nine hemiplegic patients voluntarily participated in this study. Their STS movements was analyzed in a total of nine sessions (one set of three consecutive sessions) with varying chair height and foot conditions. The biomechanical factors of the joints in the lower extremities were measured during the movements. Ground reaction force was measured using a force plate; and the other abovementioned parameters were measured using an infra-red camera. Two-way repeated analysis of variance was performed to determine the changes in biomechanical factors in the lower extremities with varying chair height and foot conditions. Results: No interaction was found between chair height and foot conditions (p>.05). All measured variables with varying chair height showed a significant difference (p<.05). Maximum joint flexion angle, maximum joint moment, and the displacement of the center of mass in foot conditions showed a significant difference (p<.05); however the maximum ground reaction force did not show a significant difference (p>.05). Conclusion: The findings suggest that hemiplegic patients can more stably and efficiently perform the STS movement with increased chair height and while they are bare-foot.

바이오파울링은 역삼투막 여과 공정에서 운전 성능을 저해하는 주요 원인이다. 이전 연구들은 분리막 표면에 발생하는 바이오파울링을 제어하기 위해서 화학적 세정제를 주입하는 방법을 주로 사용하였다. 화학적 세정제의 주입은 분리막의 손상뿐만 아니라 이차적으로 수계 오염을 발생시키기 때문에 주입 농도와 운영 방법에 주의가 요구된다. 이러한 문제를 극복하기 위해, 본 연구에서는 분리막 표면에 생물막 저해제를 고정하여 바이오파울링을 제어하는 연구를 수행하였다. 표면 고정화를 위한 방법으로 Layer-by-layer 기술을 적용하였고, 생물막저해제로 클로르헥시딘과 글루타알데하이드를 사용하였다. 막 표면의 생물막 저해제 고정화는 미생물의 부착 억제 및 사멸로 생물막 형성이 지연되어 운전 성능이 유지되는 효과를 나타냈다.

Rare earth elements (REEs) are considered to be vital to modern industry due to their important roles in applications such as permanent magnets, automobile production, displays, and many more. The imbalance between demand and supply of REEs can be solved by recycling processes. Regarding the needs of industry and society, the International Organization for Standardization, Technical Committee 298 (ISO/TC298) Rare Earths has been recently launched for developing international standards on rare earth elements. In accordance with the suggestion of its constituents, it is tentatively working to develop the appropriate standards under five working groups (WG) on terms and definitions (WG1), element recycling (WG2), environmental stewardship (WG3), packaging, labelling, marking, transport, and storage (WG4), and testing analysis (WG5). The scope and structure of ISO/TC298 on the topic of rare earths is discussed in this document.

투과증발 공정은 공비점 부근의 함수 유기화합물로부터 선택적으로 물은 분리하는 기술로 에너지 절약형 분리 기술이다. 본 연구에서는 이와 같은 투과증 발 플랜트의 개발을 위하여 α-Alumina 지지체에 합성한 NaA제올라이트 분리막 을 사용하였으며, 1 ton/day급과 250 L/batch급의 플랜트를 개발하였다. 개발한 투과증발 플랜트는 함수에탄올을 대상으로 탈수 평가를 수행하였으며, 250 L/batch급의 플랜트는 억새의 발효를 통해 생산한 함수 바이오에탄올을 이용하여 탈수 성능을 평가하였다.

The purpose of this study was to investigate the effect of taping on knee joint for patellofemoral compressive force (PCF) during stair descent for elderly women. Ten healthy elderly women voluntarily participated in this study. A three-dimensional motion analysis system and force plates were used to analyze the movements of the joints for the lower extremities. The results were as follows: There were no significant differences for the maximum PCF, maximum quadriceps contraction force and maximum knee extension moment (p>.05) but, there was a pattern decreasing all values with the taping during stair descent. There were significant differences for the knee and ankle angle on the event of maximum PCF (p<.05) and there was a pattern decreasing all values with the taping during stair descent. Therefore, taping on the knee would be effective to relieve the pain like patellofemoral pain syndrome in the knee joint.

상법 제336조 제1항에서는 주식의 양도는 주권의 교부에 의한다고 규정하고 있다. 그러나 일정한 경우 주권의 발행 전에도 주식의 양도를 인정한다. 이때는 주권의 교부없이 주식의 양도가 이루어지므로 주식의 이중양도의 가능성이 있게 된다. 그런데 주식의 양도에 관하여 상법에서는 단지 명의개서를 하지 않으면 회사에 대하여 대항할 수 없다는 취지의 규정(상법 제337조 제1항)만을 두고 있다. 만일 동일 주식이 이중으로 양도되었다면 이중 양도인 상호간에 누구에게 우선권을 인정할 것인가 하는 문제와, 회사는 이 경우 누구를 주주로 인정할 것인가라는 문제가 발생하는 바, 상법 제337조 제1항의 문언은 이러한 문제에 대한 해법을 제시하기에는 부족하다. 결과적으로, 주권발행 전 주식양도시에 양도의 효력요건과 대항요건, 그리고 대항할 수 있다는 것의 구체적인 의미에 대해서는 학설과 판례에 맡겨져 있다. 이에 대하여 다수설·판례는 주권발행전의 주식양도에 대하여 민법상의 지명채권양도의 방법에 의하고, 그 대항력도 결정된다고 한다. 이 논문은 주권발행전의 주식의 이중양도가 문제된 대법원 판례를 중심으로 검토하고 있다. 이 사안에서 이중 양수인 모두 민법상의 제3자에 대한 대항요건을 갖추지 못하였다. 그러나 제2양수인이 명의개서를 하였음에도 제1양수인은 이를 하지 못하였고, 회사는 그러한 사유를 알고 있었다. 이에 대하여 고등법원 판결은 제1양수인이 주주로 취급되어야 한다고 판시함에 반하여 대법원에서는 이중양수인 모두 제3자에 대한 대항요건을 갖추지 못하였으므로, 어느 당사자도 다른 당사자에 대하여 우위에 있지 않으며, 회사로서는 주주명부상의 주주를 주주로 취급해야 할 의무를 가지고 있으므로 주주명부의 기재에 따라서 주주로서의 권리행사의 기회를 제공한 회사의 행위에 아무런 하자가 없다는 태도를 취하였다. 기본적으로 이 논문은 대법원의 태도가 타당하다는 입장에서 논리를 전개하였다.

This study investigated the effect of a load of 15% body weight on trunk, pelvis and hip joint coordination and angle variability in subjects with and without chronic low back pain (CLBP) during an anterior load carriage task. Thirty volunteers participated in the study (15 without CLBP, 15 with CLBP). All participants were asked to perform an anterior carriage task with a load of 15% body weight. The outcome measures included the means and standard deviations for measurements of three-dimensional coordination and angle variability of the trunk, pelvis and hip joint. As CLBP patient group .06, control group .70, the correlation coefficient between the groups showed a significant difference only in trunk-pelvic in the sagittal plane (p<.05). Angle variability of CLBP patient group increased significantly in the trunk in frontal plane, the pelvis in all sagittal plane, frontal plane, transverse plane, and the hip in sagittal plane, the hip in frontal plane than angle variability of control group (p<.05). This results mean that the CLBP patient group showed a disconnected coordination pattern in the trunk-pelvis in the sagittal plane, an increased pelvic angle variability in all three planes, and hip angle variability in the sagittal, and frontal planes. The CLBP patient group may have developed a compensatory movement of the pelvis and hip joint arising from the changed stability due to the abnormal coordination patterns of the trunk-pelvic in the sagittal plane. Therefore, CLBP symptoms can potentially worsen in the pelvis and adjacent hip joint in CLBP patients who perform weight-related behaviors in their daily lives. Further research is needed to determine the three-dimensional characteristics of the electromyography and neuromuscular aspects of subjects with CLBP.

The monolayer engineering diamond particles are aligned on the oxygen free Cu plates with electroless Ni plating layer. The mean diamond particle sizes of 15, 23 and 50 μm are used as thermal conductivity pathway for fabricating metal/carbon multi-layer composite material systems. Interconnected void structure of irregular shaped diamond particles allow dense electroless Ni plating layer on Cu plate and fixing them with 37-43% Ni thickness of their mean diameter. The thermal conductivity decrease with increasing measurement temperature up to 150oC in all diamond size conditions. When the diamond particle size is increased from 15 μm to 50 μm (Max. 304 W/mK at room temperature) tended to increase thermal conductivity, because the volume fraction of diamond is increased inside plating layer.

It is known that bones get damaged by accidents and aging. Since the discovery of Bioglass, various kinds of ceramics have been also found to bond to living bone; some of these ceramics are already being clinically used as bone-repairing materials. In the present study, antibacterial calcium silicate gel (Ag-30CaO·70SiO2 gel) was prepared by sol-gel method in order to control the microstructure, which is related to the dissolution rate and induction period of apatite formation in body environment. In addition, biological Ag-30CaO·70SiO2 is tested. This was done to impart antimicrobial activity to the 30CaO·70SiO2. Ag ion was added during sol-gel synthesis to replace the H2O added during the making of the 30CaO·70SiO2 gel, which has silver solutions of various concentration. After the sol-gel process, 1N-HNO3 solution was used to wash the gel when synthesizing the gel, in order to maintain the porous structure and remove PEG, water soluble polymers. Then, the apatite forming ability of the sol-gel derived CaO-SiO2 gels was investigated using simulated body fluid (SBF), which had almost the same ion concentration as that of human blood plasma. The gels were analyzed by FT-IR spectroscopy, SEM observation, XRD, and fluorescent microscopy. The apatite was successfully created even after washing the gel; apatite is present in an amorphous state, and was found to affect the concentration of the Ag ion in cells in MC3T3 live & dead assay results. From these results, it is suggested that a good material that can be used to repair defects of nature bone is Ag-30CaO·70SiO2 gel.