The purpose of this study is to suggest a plan to improve the level of acceptance of related technologies and the transition to smart factories of small and medium-sized manufacturing enterprises by using ‘technology readiness’ and ‘integrated technology acceptance model’. To this end, the research hypothesis was verified by collecting questionnaire data from 130 small and medium- sized manufacturing companies in Korea and conducting path analysis. First, optimism affects performance expectations, social influence, and facilitation conditions, innovation affects performance expectations, effort expectations, and social influence, discomfort affects performance expectations, social influence, and facilitation conditions, and anxiety affects effort expectations, social influence and facilitation conditions. has been proven to affect Finally, performance expectations, effort expectations, social influence, and facilitation conditions were verified to have a significant positive effect on the intention to accept technology.

본 연구는 제조업 남성 근로자들의 직무스트레스와 피로와의 관계에서 사회적 지지의 매개효과를 검토하는 것을 목적으로 수행하였다. 대상: 조사대상은 제조업 공장에 근무하는 남성 근로자 352명이었다. 방법: 자료 수집은 2020년 4월 1일부터 5월 31일까지의 기간 동안에 구조화된 자기기입식 설문지를 이용한 설문조사에 의하였다. 수집된 자료는 SPSS 23.0 통계프로그램을 사용하여 상관분석, 위계적 회귀분석 및 Sobel test로 분석하였다. 결과: 연구결과, 조사대상자의 피로증상은 업무요구도와 유의한 양의 상관관계를 보인 반면, 업무의 자율성, 상자의 지지 및 동료의 지지와는 유의한 음의 상관관계를 보였다. 직무스트레스와 피로와의 관계에서 사회적 지지의 매개효과를 검증한 결과, 직무스트레스가 높을수록 사회적 지지는 낮아지는 것으로 나타났으며(F=63.93, p<0.01), 피로수준은 높아지는 것으로 나타났다(F=58.64, p<0.01). 직무스트레스를 통제한 상태에서 사회적지지가 피로에 미치는 영향 또한 통계적으로 유의하였으며(F=43.83, p<0.01), 이 때 직무스트레스의 β값이 0.352로 매개변수를 거치지 않았을 때의 β값인 0.545보다 작아 사회적지지가 매개효과를 가지는 것으로 나타났다. Sobel test 결과에서 사회적 지지는 직무스트레스와 피로의 관계에서 부분적 매개역할을 하였다(Z=-4.15, p<0.01). 결론: 위와 같은 결과는 직장에서의 사회적 지지는 근로자의 피로와 관련 있는 직무스트레스를 완화시키는 매개효과가 있을 가능성을 시사한다.

본 연구의 목적은 효소 가수분해 및 유산균 혼합발효기술을 이용하여 GABA 함량이 강화된 발효 다시마 추출물을 생산함에 있다. TLC 분석방법을 통해 GABA 생성능력이 우수한 균주 L. plantarum KCTC 21004, L. acidophilus KCTC 3164, L. sakei subsp. sakei KCTC 3598를 선정하였 다. 선정된 균주를 이용한 유산균 발효의 특성은 배양 시간이 증가 할수록 적정 산도는 증가하였고 pH 는 감소하는 경향을 나타내었다. GABA 생성능력이 우수한 3종의 균주 중 L. plantarum KCTC 21004 이 GABA 함량이 136.4 mg/100g으로 우수하였다. 이러한 연구 결과는 유산균을 이용한 GABA 생산과 정에 있어서 기초적인 자료로 제공될 것으로 판단된다.

Lightweight steel is a crucial material that is being actively studied because of increased carbon emissions, tightening regulations regarding fuel efficiency, and the emergence of UAM, all of which have been recently labeled as global issues. Hence, new strategies concerning the thickness and size reduction of steel are required. In this study, we manufacture lightweight steel of the Fe-Mn-Al-C system, which has been recently studied using the DED process. By using 2.8 wt.% low-Mn lightweight steel, we attempt to solve the challenge of joining steel parts with a large amount of Mn. Among the various process variables, the laser scan power is set at 600 and 800W, and the laser scan speed is fixed at 16.67 mm/s before the experiments. Several pores and cracks are observed under both conditions, and negligibly small pores of approximately 0.5 μm are observed.

In this study, additive manufacturing of a functionally graded material (FGM) as an alternative to joining dissimilar metals is investigated using directed energy deposition (DED). FGM consists of five different layers, which are mixtures of austenitic stainless steel (type 316 L) and low-alloy steel (LAS, ferritic steel) at ratios of 100:0 (A layer), 75:25 (B layer), 50:50 (C layer), 25:75 (D layer), and 0:100 (E layer), respectively, in each deposition layer. The FGM samples are successfully fabricated without cracks or delamination using the DED method, and specimens are characterized using optical and scanning electron microscopy to monitor their microstructures. In layers C and D of the sample, the tensile strength is determined to be very high owing to the formation of ferrite and martensite structures. However, the elongation is high in layers A and B, which contain a large fraction of austenite.

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.

This study was carried out to examine the physical characteristics of bacterial cellulose (BC) and its optimal culture condition using coffee by-products. Recently, recycling resources and employing eco-friendly materials have been raised as significant issues in the food industry. As the coffee industry develops, interests and efforts for recycling coffee wastes are also growing. This study attempted to confirm the production of BC by utilizing spent coffee grounds filtrate as a medium. In order to confirm the optimal culture conditions for BC production, different culture methods, initial pH, culture temperature, and culture period were examined. The optimal pH and temperature were 6.0 and 30oC, and the optimal culture period was 14 days. The cultivated BC was dried by hot air drying, freezedrying, and mold drying, respectively. Then, the properties of the BC films, such as tensile strength, elongation, water-solubility, thickness, and chromaticity were compared. The drying method affected the shape and structure of the final BC films. The production of BC film is expected to expand opportunities for recycling coffee by-products and contribute to solving environmental problems caused by food waste.

This study aims to investigate the physicochemical properties of meat analogs by using high and low moisture extrusion processes to create a plant-based analog burger patty material. The isolated soy protein blends of low- and high-meat analogs (LMMA and HMMA) were texturized using the twin-screw extruder equipped with a cooling die. The highest hardness, cohesiveness, chewiness, and cutting strength were observed in beef, but the highest stringiness was indicated in HMMA. The highest integrity index was seen in beef, while LMMA had the highest nitrogen solubility index (NSI). LMMA also had the highest water holding capacity (WHC) and water absorption capacity (WAC), whereas beef had the highest oil absorption capacity (OAC). LMMA had the highest emulsifying activity (EA) and emulsion stability (ES) in emulsifying properties. Further, the highest protein digestibility was revealed in LMMA. This study suggested that extrusion process types influence the quality of meat analog, which could be the elementary source for manufacturing the analog burger patty.

This study demonstrates the effect of the compaction pressure on the microstructure and properties of pressureless-sintered W bodies. W powders are synthesized by ultrasonic spray pyrolysis and hydrogen reduction using ammonium metatungstate hydrate as a precursor. Microstructural investigation reveals that a spherical powder in the form of agglomerated nanosized W particles is successfully synthesized. The W powder synthesized by ultrasonic spray pyrolysis exhibits a relative density of approximately 94% regardless of the compaction pressure, whereas the commercial powder exhibits a relative density of 64% under the same sintering conditions. This change in the relative density of the sintered compact can be explained by the difference in the sizes of the raw powder and the densities of the compacted green body. The grain size increases as the compaction pressure increases, and the sintered compact uniaxially pressed to 50 MPa and then isostatically pressed to 300 MPa exhibits a size of 0.71 m. The Vickers hardness of the sintered W exhibits a high value of 4.7 GPa, mainly due to grain refinement.

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.

멤브레인은 분리 기술 및 다양한 사용처에 따라서 유기물, 액체, 용질, 증기, 기체, 이온 또는 전자 등 다양한 물질 을 선택적으로 분리할 수 있다. 멤브레인은 크게 대칭막과 비대칭막으로 나누며, 기공의 유무에 따라 다공성과 비다공성으로 분류된다. 또한 멤브레인의 계면은 분자적으로 균일하거나, 또는 화학적으로 또는 물리적으로 불균일할 수 있다. 제조기술로 는 용융 압출 제조법, 연신법, 템플레이트 침출법, 트랙-에치법, 용액 캐스팅법, 상전이법 및 용액 코팅법 등이 있다. 제조된 멤브레인은 정밀여과, 한외여과, 나노여과, 역삼투, 기체분리 및 에너지 분야와 같은 다양한 응용 분야에 적용될 수 있다. 본 총설에서는 멤브레인의 분류 및 종류에 따른 제조 방법에 대한 튜토리얼을 제공한다.

Production management in the automobile parts industry is carried out according to the production plan of the customer, so it is important to prevent shortages in product supply. As the product composition became increasingly complex, the MES System was built for the purpose of efficient production plan management and inventory management, but its utilization is low. This study analyzed the problems of the MES system and sought to improve it. Through previous studies, it was confirmed that the inventory management of the pull approach that actually occurred in the warehouse is more suitable than the push approach based on the forecast of the warehouse for the volatility, complexity, and uncertainty of orders in the auto parts industry. To realize this, we tried distributed MRP by using the ADO function of VBA to link the standard information of the MES system with Excel and change the structure of the BOM table. Through this, it can help increase the accuracy of production planning and realize efficient inventory management, thereby increasing the utilization of the MES system in the auto parts industry and enhancing the competitiveness of the company.

광전기화학 성능을 향상시키기 위해 각 ZnO, ZnSe과 g-C3N4 소재의 장점을 살리도록 3성분계 적층 구조를 디자 인했다. 용액공정으로 FTO 기판위에서 ZnO 나노로드 어레이가 성장하도록 한 후 ZnO표면에 Se을 부착시켜 ZnO표면에 서 ZnSe층이 형성 되도록 이온 치환법을 도입하였다. ZnO/ZnSe 나노로드 위에 g-C3N4 층을 스핀코팅 한 후 각 층이 화 학적 접합이 되도록 질소 분위기 하에서 열처리를 하였다. AM 1.5G, 0.5 V 외부전압하에서 각 적층구조별로 광전기화학 적 전류밀도를 측정하였고 비교 결과 ZnO/ZnSe/g-C3N4 나노로드가 ZnO 및 ZnO/ZnSe 나노로드에 비하여 보다 높은 광 전류 밀도가 측정되었다. 수직 정렬된 ZnO 육각 프리즘형태는 큰 비표면적과 축 방향을 따라 전자 흐름을 원활히 하고, ZnSe 층은 비표면적과 광흡수 범위를 더욱 넗히는 효과를 가져왔다. 이로 인하여 ZnO/ZnSe/g-C3N4 삼원 접합 전극의 향상된 성능은 가시광선 흡수범위 확장, 전하 분리 강화 및 전자 전도도 향상으로 인한 시너지 효과에 기인되는 것으로 판단된다.

It was legislated in Korea that the small-sized enterprise with fewer than 50 employees should appoint at least one managing officer in order to improve safety and health of the employees since 2016. Study on the effectiveness of this legislation is hardly found, however. This study tried to evaluate effectiveness of the regulations for appointing the safety and health management officer in small-sized manufacturing companies and make suggestions to improve it. It was done by pairwise comparison between the level of safety and health achievement of 52 companies before and after the legislation. A scorecard system and questionnaires were devised for assessing the level of safety and health achievement and surveying awareness and practice of the regulation in the field. Results from quantitative and qualitative analyses performed in the study confirm that the safety and health achievement score has increased significantly after appointing the managing officer. It is also revealed that the lack of expertise and motivation of the appointed officer would yield pointless outcomes. Recommendations to make it better the effectiveness of the regulation are: to administrate requirements more strictly to be appointed as a safety and health management officer, to revise the curriculum to train the expertise of the appointed officers, and to expand financial support of the government to settle the safety and health management system.