Mid-sized manufacturing companies, which account for 0.7%(5,480 companies), 13.8%(1.169 million persons) of total employment, and 15.7% of total sales, have recently experienced a lot of difficulties in management activities due to the impact of COVID-19, the U.S.-China trade war, and the collapse of global supply chains. To overcome this, revitalization of quality management activities to strengthen corporate competitiveness is emerging as an urgent task. In order for these quality management activities to achieve their intended purpose, the positive leadership of corporate managers is very important above all else. There have been many studies related to positive leadership, but most have focused on charismatic leadership and transformational leadership centered on large companies or small and medium-sized enterprises. Therefore, this study aims to present ways to strengthen the leadership of managers by empirically analyzing how the positive leadership of managers of mid-sized manufacturing companies, which was relatively under-researched, affects quality management activities and Business performance(Balanced Score Card; BSC).

There is a considerable amount of research on metal material product worker’s hearing loss caused by noise that comes from manufacturing process. A further investigation that characterizes the sound that comes from manufacturing process of metal material products. however. To do this, a noise management plan is needed. It should include a generated sound process from the main sources of disturbance at manufacturing process areas. And a soundproof measurement will identify the amount of noise reduction needed for a hearing-safe working environment. Finally, researchers in this study measured tests on the noise and the vibration process, and the noise caused by operations allowed for an investigation on the suitability of certain environmental conditions. Noise-related programs can be used to predict the noise distribution of the noise level characteristic. This can help identify and reduce the presence of sound interference through sound proofing measures.

A Cu-15Ag-5P filler metal (BCuP-5) is fabricated on a Ag substrate using a high-velocity oxygen fuel (HVOF) thermal spray process, followed by post-heat treatment (300oC for 1 h and 400oC for 1 h) of the HVOF coating layers to control its microstructure and mechanical properties. Additionally, the microstructure and mechanical properties are evaluated according to the post-heat treatment conditions. The porosity of the heat-treated coating layers are significantly reduced to less than half those of the as-sprayed coating layer, and the pore shape changes to a spherical shape. The constituent phases of the coating layers are Cu, Ag, and Cu-Ag-Cu3P eutectic, which is identical to the initial powder feedstock. A more uniform microstructure is obtained as the heat-treatment temperature increases. The hardness of the coating layer is 154.6 Hv (as-sprayed), 161.2 Hv (300oC for 1 h), and 167.0 Hv (400oC for 1 h), which increases with increasing heat-treatment temperature, and is 2.35 times higher than that of the conventional cast alloy. As a result of the pull-out test, loss or separation of the coating layer rarely occurs in the heat-treated coating layer.

Aluminum alloys are extensively employed in several industries, such as automobile, aerospace, and architecture, owing to their high specific strength and electrical and thermal conductivities. However, to meet the rising industrial demands, aluminum alloys must be designed with both excellent mechanical and thermal properties. Computer-aided alloy design is emerging as a technique for developing novel alloys to overcome these trade-off properties. Thus, the development of a new experimental method for designing alloys with high-throughput confirmation is gaining focus. A new approach that rapidly manufactures aluminum alloys with different compositions is required in the alloy design process. This study proposes a combined approach to rapidly investigate the relationship between the microstructure and properties of aluminum alloys using a direct energy deposition system with a dual-nozzle metal 3D printing process. Two types of aluminum alloy powders (Al-4.99Si-1.05Cu-0.47Mg and Al-7Mg) are employed for the 3D printing-based combined method. Nine types of Al-Si-Cu-Mg alloys are manufactured using the combined method, and the relationship between their microstructures and properties is examined.

In this study, a new manufacturing process for a multilayer-clad electrical contact material is suggested. A thin and dense BCuP-5 (Cu-15Ag-5P filler metal) coating layer is fabricated on a Ag plate using a high-velocity oxygen-fuel (HVOF) process. Subsequently, the microstructure and bonding properties of the HVOF BCuP-5 coating layer are evaluated. The thickness of the HVOF BCuP-5 coating layer is determined as 34.8 μm, and the surface fluctuation is measured as approximately 3.2 μm. The microstructure of the coating layer is composed of Cu, Ag, and Cu-Ag-Cu3P ternary eutectic phases, similar to the initial BCuP-5 powder feedstock. The average hardness of the coating layer is 154.6 HV, which is confirmed to be higher than that of the conventional BCuP-5 alloy. The pull-off strength of the Ag/BCup-5 layer is determined as 21.6 MPa. Thus, the possibility of manufacturing a multilayer-clad electrical contact material using the HVOF process is also discussed.

본 연구는 나노섬유를 제조하는데 빠르고 효과적인 전기방사법을 이용하여 PVA(Polyvinyl alcohol)와 AgNO3를 혼합하여 제조한 용액을 금속산화물 기반 나노 섬유로 이루어진 투명 전극을 제조하고 그 특성을 분석하였다. PVA/AgNO3 혼합 용액을 전기방사법을 이용하여 유리기판 위에 나노 섬유 구조체 형태로 방사하여 250 ℃에서 2 시간 동안 열처리 과정을 통해 전기 전도성이 향상된 은 나노 섬유 기반 투명 전극을 제조하였다. 제조된 투명전극은 four-point probe 장비를 이용하여 전기적 특성을 분석하였으며, UV - Vis spectrophotometer 를 이용하여 제조된 투명전극의 투과도를 확인하였다. 또한, Scanning Electron Microscopy (SEM)과 Energy Dispersive Spectrometer(EDS)를 통해 은 나노 섬유의 표면 특성과 성분을 확인하였다. 이러한 분석들을 통해, 전기 방사 시간에 따른 면 저항과 투과도의 최적화된 조건을 확인할 수 있었으며, 은 나노 섬유로 이루어진 투명 전극은 전기적, 광학적, 기계적 특성이 우수하여 태양전지, 디스플레이, 터치스크린과 같은 차세대 유연 디스플레이에 적용 가능성을 보여주었다.

In this study, we fabricate a thin- and dense-BCuP-5 coating layer, one of the switching device multilayers, through a plasma spray process. In addition, the microstructure and macroscopic properties of the coating layer, such as hardness and bond strength, are investigated. Both the initial powder feedstock and plasma-sprayed BCuP-5 coating layer show the main Cu phase, Cu-Ag-Cu3P ternary phases, and Ag phase. This means that microstructural degradation does not occur during plasma spraying. The Vickers hardness of the coating layer was measured as 117.0 HV, indicating that the fine distribution of the three phases enables the excellent mechanical properties of the plasma-sprayed BCuP-5 coating layer. The pull-off strength of the plasma-sprayed BCuP-5 coating layer is measured as 16.5 kg/cm2. Based on the above findings, the applicability of plasma spray for the fabrication process of low-cost multi-layered electronic contact materials is discussed and suggested.

본 연구에서는 “이온젤” 이라고 불리는 고분자 기반의 PVA(polyvinyl alcohol) 기반의 고체 전 해질에 이온성 액체 BMIMBF4 (1-buthyl-3-methylimidazolium tetrafluoroborate)를 첨가하여 제조한 전 고체 전해질과 활성탄소와 금속유기골격체 복합재료 기반의 전극 재료를 이용하여 슈퍼커패시터를 제작 하였으며, 유기골격체의 유 무에 따른 전기화학적 특성을 분석하여 보았다. 슈퍼커패시터의 전기화학적 특 성은 순환전압전류법(CV), 전기화학적 임피던스 분광법(EIS) 및 전정류 충·방전법(GCD)을 통하여 비교 및 분석하여 보았다. 그 결과로, 금속유기골격체가 함유되지 않은 슈퍼커패시터의 전기용량값은 380 F/g 으로 확인 할 수 있었고, 이 값은 금속유기골격체를 첨가하였을 때 340 F/g로 감소하는 현상을 확인할 수 있었 다. 이러한 결과로 1 wt%의 금속유기골격체의 함유량은 전기화학적 특성 감소에 영향을 주는 것으로 사료 되며 이러한 결과를 바탕으로 금속유기골격체의 첨가량을 최적화 할 필요가 있다고 판단된다

The co-doping effect of aliovalent metal ions such as Mg2+, Ca2+, Sr2+, Ba2+, and Zn2+ on the photoluminescence of the Y2O3:Eu3+ red phosphor, prepared by spray pyrolysis, is analyzed. Mg2+ metal doping is found to be helpful for enhancing the luminescence of Y2O3:Eu3+. When comparing the luminescence intensity at the optimum doping level of each Mg2+ ion, the emission enhancement shows the order of Zn2+ Ba2+ > Ca2+ > Sr3+> Mg2+. The highest emission occurs when doping approximately 1.3% Zn2+, which is approximately 127% of the luminescence intensity of pure Y2O3:Eu3+. The highest emission was about 127% of the luminescence intensity of pure Y2O3:Eu3+ when doping about 1.3% Zn2+. It is determined that the reason (Y, M)2O3:Eu3+ has improved luminescence compared to that of Y2O3:Eu3+ is because the crystallinity of the matrix is improved and the non-luminous defects are reduced, even though local lattice strain is formed by the doping of aliovalent metal. Further improvement of the luminescence is achieved while reducing the particle size by using Li2CO3 as a flux with organic additives.

Recently, as the quality of life of modern people improves, interest in environmental noise is gradually increasing. As the public's awareness of environmental rights increased, it was necessary to grasp the actual condition of the noise source and systematic noise management plan. The data is expected to be used as a response to noise-related complaints. As a result measured using the factory noise monitoring system, the amount of data measured every 5 minutes from 00:00 to 24:00 can obtain 288 noise levels and frequency characteristics per day, and frequency using 1/3 octave-band. The analysis reveals what frequency range affects the noise from the metal working plant near the office. In addition, it can be seen that it is possible to compare with the reference value by using the stored data divided into night time, day time, and evening time for each time zone, and it is determined that it is possible to secure smooth data about the noise source to be measured.

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.

The Fe-22wt.%Cr-6wt.%Al foams were fabricated via the powder alloying process in this study. The structural characteristics, microstructure, and mechanical properties of Fe-Cr-Al foams with different average pore sizes were investigated. Result of the structural analysis shows that the average pore sizes were measured as 474 μm (450 foam) and 1220 μm (1200 foam). Regardless of the pore size, Fe-Cr-Al foams had a Weaire-Phelan bubble structure, and α-ferrite was the major constituent phase. Tensile and compressive tests were conducted with an initial strain rate of 10−3 /s. Tensile yield strengths were 3.4 MPa (450 foam) and 1.4 MPa (1200 foam). Note that the total elongation of 1200 foam was higher than that of 450 foam. Furthermore, their compressive yield strengths were 2.5 MPa (450 foam) and 1.1 MPa (1200 foam), respectively. Different compressive deformation behaviors according to the pore sizes of the Fe-Cr-Al foams were characterized: strain hardening for the 450 foam and constant flow stress after a slight stress drop for the 1200 foam. The effect of structural characteristics on the mechanical properties was also discussed.

The purpose of this study was to establish the noise characteristics of noise sources and the corresponding noise reduction measures during each manufacturing process closest to the workers in the metalworking factory. To this end, the noise generated in the manufacturing process of metal products was measured and analyzed, and the frequency characteristics of noise sources and the causes of noise were identified. The noise map was used to predict the noise reduction effect. Moreover, it is expected that this will ultimately contribute to the reduction of human risks caused by the noise of the civil environment around metalworking factories.