• 한국산업보건학회지
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• 제32권4호
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• pp.425-434
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• 2022

Objectives: This study analyzes TVOC concentrations in root industry workplaces in order to prevent probable occupational disease among workers. Root industry includes all the infrastructure of manufacturing, such as casting and molding. Methods: Real-time TVOC sensors were deployed in three root industry workplaces. We measured TVOC concentrations with these sensors and analyzed the results using a data-analysis tool developed with Python 3.9. Results: During the study period, the mean of the TVOC concentrations remained in an acceptable range, 0.30, 2.15, and 1.63 ppm across three workplaces. However, TVOC concentrations increased significantly at specific times, with respective maximum values of 4.98, 28.35, and 26.65 ppm for the three workplaces. Moreover, the analysis of hourly TVOC concentrations showed that during working hours or night shifts TVOC concentrations increased significantly to higher than twice the daily mean values. These results were scrutinized through classical decomposition results and autocorrelation indices, where seasonal graphs of the corresponding classical decomposition results showed that TVOC concentrations increased at a specific time. Trend graphs showed that TVOC concentrations vary by day. Conclusions: Deploying a real-time TVOC sensor should be considered to reflect irregularly high TVOC concentrations in workplaces in the root industry. It is expected that the real-time TVOC sensor with the presented data analysis methodology can eradicate probable occupational diseases caused by detrimental gases.

• Advances in nano research
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• 제15권1호
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• pp.49-57
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• 2023

As composite materials are used in many applications, the modern world looks forward to significant progress. An overview of the application of composite fiber materials in sports equipment is provided in this article, focusing primarily on the advantages of these materials when applied to sports equipment, as well as an Analysis of the influence of sports equipment of fiber-reinforced composite material on social sports development. The present study investigated surface morphology and physical and mechanical properties of S-glass fiber epoxy composites containing Al₂O₃ nanofillers (for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%). A mechanical stirrer and ultrasonication combined the Al₂O₃ nanofiller with the matrix in varying amounts. A compression molding method was used to produce sheet composites. A first physical observation is well done, which confirms that nanoparticles are deposited on the fiber, and adhesive bonds are formed. Al₂O₃ nanofiller crystalline structure was investigated by X-ray diffraction, and its surface morphology was examined by scanning electron microscope (SEM). In the experimental test, nanofiller content was added at a rate of 1, 2, and 3% by weight, which caused a gradual decrease in void fraction by 2.851, 2.533, and 1.724%, respectively, an increase from 2.7%. The atomic bonding mechanism shows molecular bonding between nanoparticles and fibers. At temperatures between 60 ℃ and 380 ℃, Thermogravimetric Analysis (TGA) analysis shows that NPs deposition improves the thermal properties of the fibers and causes negligible weight reduction (percentage). Thermal stability of the composites was therefore presented up to 380 ℃. The Fourier Transform Infrared Spectrometer (FTIR) spectrum confirms that nanoparticles have been deposited successfully on the fiber.

• 한국주거학회논문집
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• 제26권4호
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• pp.23-32
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• 2015

The purpose of this research is to analyze characteristics and related factors of IAQ (Indoor Air Quality) in newly built wooden houses by measuring pre and post occupancy. The subjects were five wooden houses which were built with similar materials and completed from July to December 2013. Measuring factors were TVOC, HCHO, PM10, $CO_2$, CO, indoor temperature, and relative humidity. As the result of pre occupancy measuring, the houses that revealed the lowest TVOC concentration or HCHO concentration were satisfied with "the standard for newly built apartment houses". Therefore, IAQ by the wooden structures is considered to be in good condition. However, in cases of partial value exceeded the standard, the reason is analyzed to be the materials of molding, wrapping doors, built-in closet, or kitchen furniture, etc. rather than structure materials. Most PM10 concentration level showed slightly below "the standard for occupied multi-use facilities". Remaining of construction dust was considered to be the reason. As the result of post occupancy measuring, every value except of one subject's TVOC concentration was lower than pre occupancy, explaining the importance of natural ventilation.

• 한국융합학회논문지
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• 제8권12호
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• pp.23-29
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• 2017

본 논문은 1mm 이하의 극소형 패키지 개발을 위한 금형 기술을 소개한다. 또한 이 금형 기술을 사용하여 산출된 결과들의 오류 패턴을 분석한다. 기존의 극소형 금형 구조는 일체형이었는데 EDM의 표면이 거칠어 오류율을 증가시키는 원인이 되었다. 이 원인으로 인해 금형의 크기를 더 줄이는데 방해요소로 작용하였다. 이에 반해 제안하는 금형기술은 기존의 일체형 방식에서 벋어나 조립식 방법을 사용하여 일체식의 한계를 극복하고자 한다. 또한 새로 제안된 금형 구조를 이용해 산출한 결과에 결함 패턴을 분류하고, 각 패턴의 발생 확률을 분석하여 검출기를 개발하려는 기초 자료로 사용하려 한다.

• 한국안전학회지
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• 제30권4호
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• pp.32-38
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• 2015

In this paper, we analyzed the vehicle fire accidents due to damage of vehicle's electrical components, which is applied to a vehicle. In recent development of electrical components technology, approximately 40% of vehicle manufacturing parts have applied electronic circuit technology. Phenomenon such deterioration of insulating performance or electric breakdown on the vehicle's electrical components and printed circuit boards(PCBs) resulted from moisture, contamination and aging due to repetitive operations, lead to the vehicle fire. Therefore, the application of electrical components with adequate electric capacity for vehicle and usage of molding techniques using a non-combustible materials to shut off the oxygen should be applied in order to prevent vehicle fire due to damage of the electrical components and PCBs.

• 대한기계학회논문집
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• 제15권6호
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• pp.1933-1947
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• 1991

본 연구에서는 특징형상기반 CAD 시스템의 기계가공을 고려한 기하학적 모델 링 기능과 부형상의 합성과 해석을 위한 사출성형에 관한 광범위한 지식을 연계, 종합 한 형태의 지식형 CAD 시스템을 제안하였다.

• 한국기계가공학회지
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• 제1권1호
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• pp.79-88
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• 2002

High speed machining system have been used in industrial because it is effective to a material manufacturing with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. Therefore this study proposed to decide best manufacturing cutting condition for surface roughness and rapid manufacturing tune by using computer Image processing system and 3D modelling. Until the 16,000 rpm, the surface roughness is decreased rapidly, but it is not over that. The 22,000 rpm is the spindle speed with the optimum surface in the high speed end-milling. In the case of the feed rate with 2,000 mm/mm and 8,000 mm/mm, the surface roughness is better than 4,000 mm/min and 6,000 mm/min. By using the 3D modelling, it is effectively represented shape characteristics of working surface m high speed end-milling.

• 한국가구학회지
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• 제28권4호
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• pp.371-379
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• 2017

This study established the scope of the main contents and interpretation of wooden product design using the CNC manufacturing technology as well as the basic concepts of which were defined, accordingly. After coming up with the definition of the CNC wood manufacturing technology from the academic point of view, a design study, using the practical CNC manufacturing technology, was conducted by analyzing and summarizing the contents of each process. In addition, data research and analysis including review on literatures and case studies of existing products were promoted besides design development through application of the design concepts, ergonomics, principle of molding, etc. Ultimately, this study suggested the step-by-step procedure in design drawing, 3D modeling, CAD/CAM data production, CNC manufacturing, and prototype completion together with figures. Through this, the study proposed a standard manufacturing guideline for wood product design using digital manufacturing technology. Base on such efforts, the advantages and points for improvement in product design using CNC manufacturing technology and the future direction of development were forwarded. Meanwhile, a prototype image that was developed through collaborative efforts between the academic circle and field workers was presented to help the case study on the wooden product design technique using CNC.

• 한국산업정보학회논문지
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• 제20권1호
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• pp.57-62
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• 2015

최근 인체에서 방출되는 적외선을 감지하여 질병부위를 진단하는 의료기기로써 체열촬영이 가능한 열화상카메라가 활용되고 있다. 본 연구에서는 칼코지나이드 소재 적외선 성형렌즈를 채용한 열화상카메라 시제품을 제작하고, 열영상 분석을 통해 체열진단 장비로써의 시제품 성능을 검증하였다. 열화상카메라 시제품은 $20{\sim}50^{\circ}C$에서 체열이 촬영됨을 확인 하였고, 온도분해능(NEDT) 측정결과 87.7mK의 우수한 결과를 나타냈다. 이를 통해 칼코지나이드 성형렌즈를 채용한 열화상카메라 시스템이 체열진단을 위한 의료기로 사용가능함을 확인 하였다.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2228-2236
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• 2002

The axial piston pump by which the mechanical energy is converted into hydraulic energy has been widely used in a press, a injection molding machine and construction equipments due to the high specific power compared to the electric power system. In this paper, the one-piece shoe holder spring of the axial piston pump to simplify its structure and reduce this manufacturing cost was designed and tested. The finite element analyses using the 3-D shell element and contact element were performed to determine the thickness, width and initial angle of the shoe holder spring. Also, the compressive tests of the shoe holder spring were performed and their results were compared with those of the finite element analysis. Also, the performance and endurance limit of axial piston pump with the shoe holder spring were tested and evaluated.