• Design & Manufacturing
• /
• 제17권1호
• /
• pp.7-12
• /
• 2023

Recently, with the emergence of the 4th industrial revolution, the demand for smart factories and factory automation is increasing. In this study, a tool life prediction program was developed to select optimal machining conditions using CNC milling equipment, which is widely used in flexible production and automation. The equipment used in the experiment was Hwacheon Machine Tool's 5-axis machining equipment, and the tool used was a 17F2R tool. For the machining path, the down-milling cutting method was selected and long-term machining was performed. The analysis standard for side wear on the tool was set at 0.1 to 0.2 mm, and tool life data and wear data were obtained in the cutting experiment. The program was created through the data obtained from the experiment, and a prediction rate of over 90% was secured when comparing the experimental data and the predicted data.

• Composites Research
• /
• 제36권4호
• /
• pp.264-269
• /
• 2023

Spent coffee grounds (SCG) are a ubiquitous byproduct of coffee consumption, representing a significant waste management challenge, as well as an untapped resource for economic development and sustainability. Improper disposal of SCG can result in environmental problems such as methane emissions and leachate production. This study aims to investigate the physicochemical properties of SCG and their potential as a reinforcement material in polypropylene (PP) to fabricate an eco-friendly composite via extrusion and injection molding, with SCG filler ratios ranging from 5-20%. To evaluate the effect of SCG on the morphological and mechanical properties of the bio- composite, thermogravimetric analysis, SEM, tensile, flexural, and impact tests were conducted. The results demonstrated that the addition of SCG lead to a slight increase in brittleness of the composite but did not significantly affect its mechanical properties. Impressively, the presence of a significant organic component in SCG contributed to the enhanced thermal performance of PP/SCG composites. This improvement was evident in terms of increased thermal stability, delayed onset of degradation, and higher maximum degradation temperature as compared to pure PP. These findings suggest that SCG has potential as a filler material for PP composites, with the ability to enhance the material's properties without compromising overall performance.

• 열처리공학회지
• /
• 제36권3호
• /
• pp.137-144
• /
• 2023

Micro electro mechanical systems (MEMS) and precision machines require excellent friction and wear characteristics to improve energy efficiency generated during sliding motion. In this study, DLC thin film with high hardness and low friction was deposited on STS304 substrate material by CVD method, and dot-shaped convex and concave micropatterns were fabricated by photolithography process. The diameter of the pattern was 20 ㎛, the pitch was 40 ㎛, and a pattern having a mesh type arrangement was fabricated and an abrasion test was performed. The results of the wear test on the micro pattern confirmed that the friction coefficient characteristics were improved compared to STS 304 and DLC thin films. In addition, in this result, the micro-pattern showed 11.4% more improved friction coefficient than the DLC thin film. The friction coefficient characteristics for convex and concave patterns of the same size showed almost similar results.

• 대한안전경영과학회지
• /
• 제25권2호
• /
• pp.159-165
• /
• 2023

The entire industry is increasing the use of big data analysis using artificial intelligence technology due to the Fourth Industrial Revolution. The value of big data is increasing, and the same is true of the production technology. However, small and medium -sized manufacturers with small size are difficult to use for work due to lack of data management ability, and it is difficult to enter smart factories. Therefore, to help small and medium -sized manufacturing companies use big data, we will predict the gross production time through machine learning. In previous studies, machine learning was conducted as a time and quantity factor for production, and the excellence of the ExtraTree Algorithm was confirmed by predicting gross product time. In this study, the worker's proficiency factors were added to the time and quantity factors necessary for production, and the prediction rate of LightGBM Algorithm knowing was the highest. The results of the study will help to enhance the company's competitiveness and enhance the competitiveness of the company by identifying the possibility of data utilization of the MES system and supporting systematic production schedule management.

• 천문학회보
• /
• 제45권1호
• /
• pp.68.2-68.2
• /
• 2020

UVO-Multiband Polarizing Imager System (UVOMPIS) is an ultraviolet to visible light multi-wavelength polarization/imaging system for Compact Advanced Satellite. We developed Linear Astigmatism Free-Three Mirror System (LAF-TMS) D200F2 as an optical system of UVOMPIS which has an entrance pupil diameter of 200 mm, a focal ratio of 2, a field of view of 2° × 4°. LAF-TMS is a confocal off-axis reflecting telescope system that removes linear astigmatism, and its all mirrors (M1, M2, M3) are optimized with the freeform surface to reduce high-order aberrations. Through the sensitivity analysis and Monte-Carlo simulation as the tolerance analysis, we can confirm the feasibility of the system, relatively sensitive parameters (tilt, decenter, despace, surface RMS error), and considerations for optomechanical design. From the sensitivity analysis, we can discover the relatively sensitive optical alignment parameters to a single perturbation. Further more, in the monte-carlo simulation, we investigate the minimum tolerance budget satisfying the required optical performance and whether the tolerance range is satisfied within manufacturing error.

• 융합보안논문지
• /
• 제22권3호
• /
• pp.13-18
• /
• 2022

IT 기술의 급속한 발전과 함께 기존 산업과의 융합을 통해 4차 산업혁명 기술을 기반으로 프로세스의 간소화 및 생산성을 높일 수 있는 스마트 제조가 증가하고 있으며, 이와 비례하여 공급망 공격에 대한 보안위협도 증가하고 있다. 공급망 공격의 경우 사전 탐지가 힘들고 피해 규모가 매우 크다는 점 때문에 차세대 보안 위협으로 부상하고 있으며 이에 따른 탐지 기법에 대한 연구가 필요하다. 따라서 본 논문에서는 오픈소스 기반 분석 솔루션인 ELK Stack과 Sysmon을 통해 다중 환경에서 실시간으로 로그를 수집, 저장, 분석 및 시각화하여 공급망 공격에 대한 이상 행위 등의 정보를 도출하여 효율적인 탐지 기법을 제공하고자 한다.

• 소성∙가공
• /
• 제32권1호
• /
• pp.5-11
• /
• 2023

The aim of this study is to manufacture an aluminum pipe yoke of automotive steering system for lightweight. In a multistage cold forging process for aluminum pipe yoke, the surface defects frequently occur due to excessive deformation or friction during extrusion process for forming hollow pipe part. It is import to reduce the friction between the material and the forging die. This study investigated a multistage forging process with sliding die to reduce friction for aluminum pipe yoke. After evaluating by FE analysis, the forging experiment with the sliding die was carried out. As a result, it was possible to manufacture a sound aluminum pipe yoke.

• Design & Manufacturing
• /
• 제16권2호
• /
• pp.13-19
• /
• 2022

Recently, electric vehicles are gaining popularity among many domestic and foreign users due to their eco-friendly advantages of reducing fine dust and environmental greenhouse gases. As the demand and supply of electric vehicles increase, the demand for electric vehicle charging infrastructure is also growing together. Many users are experiencing inconvenience due to poor charging infrastructure, which makes them hesitant to buy electric vehicles. Research on the user experience of chargers in apartment complexes, a common residential type in Korea, is being conducted somewhat, but research on the design of electric vehicle charging devices in public places is insufficient. The purpose of this research is to identify user requirements and complaints based on the product design of the electric vehicle charger in public places and propose a new electric vehicle product design concept that meets the requirements. The research method understood the charging base and status of electric vehicles in public places through literature research and examined and analyzed the characteristics and problems of product design cases that improved the charging problem of electric vehicles recently released in the market. It is intended to identify and analyze the problems of the charging device product design through user interviews, a qualitative research method, and based on this, it is intended to propose a user-centered product design concept that improves major complaints.

• 한국초전도ㆍ저온공학회논문지
• /
• 제25권4호
• /
• pp.65-69
• /
• 2023

Hydrogen is an eco-friendly energy source and is being actively researched in various fields around the world, including mobility and aerospace. In order to effectively utilize hydrogen energy, it should be used in a liquid state with high energy storage density, but when hydrogen is stored in a liquid state, BOG (boil-off gas) is generated due to the temperature difference with the atmosphere. This should be re-condensed when considering storage efficiency and economy. In particular, large-capacity liquid hydrogen storage tank is required a gaseous helium circulation cooling system that cools by circulating cryogenic refrigerant due to the increase in heat intrusion from external air as the heat transfer area increases and the wide distribution of the gas layer inside the tank. In order to effectively apply the system, thermo-hydraulic analysis through process analysis is required. In this study, the condenser design and system characteristics of a gaseous helium circulation cooling system for BOG recondensation of a liquefied hydrogen storage tank were compared.

• 한국항공운항학회지
• /
• 제31권3호
• /
• pp.133-141
• /
• 2023

In the recent context of the Fourth Industrial Revolution, there is growing interest in digital transformation and smart factory as a focal point. But, the Aerospace and Defense (A&D) sector has seen limited research on digital transformation, primarily concentrating on digitally-driven areas. The study validates hypotheses pertaining to the factors that facilitate successful digital transformation within the A&D sector and the influence of digital leadership and dynamic capabilities, employing statistical tools like SPSS and AMOS. The comprehensive analysis reveals that, similar to manufacturing industries, digital leadership in A&D companies exerts an influence on successful digital transformation through dynamic capabilities. Furthermore, digital transformation within the A&D sector has a positive impact on firm performance. This paper offers empirical insights into digital transformation within the A&D sector, shedding light on how successful digital transformation can be achieved within the domestic A&D industry.