• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.7-12
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• 2017

It is assumed that the buckling and cutting conditions depending on the slenderness ratio will affect the machining quality of the rotary boring tool mounted on a milling machine. In this study, the boring cutter was designed and fabricated to precisely create the Ø30 hole. Through the performance evaluation, the accuracy of the hole according to the slenderness ratio and cutting conditions was analyzed, and the following conclusions were obtained. The higher the RPM, the smaller the change in the working diameter, and the smaller the hole. Next, the smaller the slenderness ratio, the smaller the change in straightness due to the change in cutting conditions. Finally, the slenderness ratio also affects the tendency for changes in the concentricity. The larger the slenderness ratio, the more sensitive the concentricity to changes in cutting conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.412-417
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• 2005

The objective of study is design and structural analysis of multi-axis drill machine for PCB. This is able to reduce the unit cost of manufacture and to ensure safety, that is with the result of analysis by design the multi-axis drill machine for the use of PCB to enhancing suitability and exactitude in mass production the process of PCB.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.110-117
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• 1997

Alloy 690 제1열 시제 전열관을 U 굽힘 가공할 시 전열관에 도입된 표면 잔류응력 및 굽힘 단면에서 치수변화 (벽두께, 진원도)를 위치별로 측정하여 평가하였다. 외측호(extrados)의 표면 잔류응력은 $\psi$=0$^{\circ}$에서 축 방향 응력이 -319 MPa (압축)로 가장 높았으며, 내측호(intrados)는 $\psi$=0$^{\circ}$, 160$^{\circ}$ 위치인 천이영역 부관에서 응력 변화가 크게 되는 경향을 보였다 측면(flank)은 인장 잔류응력으로 $\psi$=90$^{\circ}$(apex)에서 최대 190 MPa 로 축방향 응력으로 나타났다. 잔류응력치는 벽두께 보다는 진원도 변화와 일치되어 나타났으며, 시제 전열관의 벽두께 및 진원도는 ASTM의 치수 허용치 내에 포함되는 것으로 평가되었다. 잔류응력 측정은 스트레인 게이지를 이용한 구멍뚫기 방법 (Hole-Drilling Method)을 사용하였다.

• Transactions of Materials Processing
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• v.28 no.3
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• pp.154-158
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• 2019

The hole expansion tests using conical punch, flat punch or hemispherical punch are widely used for stretch flangeability verification of HSS. In this study, we investigate the strain distribution on the shear edges of the hole expansion test using grid marking and a projector. A small crack at the edge is distributed, resulting in a large gap between the HER and the crack strain. The strain distribution at the edges is irregular due to anisotropy of sheet metal. While an edge perpendicular to the rolling direction indicate a lower strain level compared to an edge parallel to the rolling direction, edge cracks occur at the edge perpendicular to the rolling direction. To predict the manifestation of edge cracks in FE analysis, the result of the hole expansion test with a crack strain measurement may well be a better tool than FLD. In this case, the level of strain and the direction of the edge relative to the rolling direction should be well considered.

• Composites Research
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• v.23 no.6
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• pp.55-60
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• 2010

In this paper, tensile and bending tests of glass/polypropylene composite (Twintex) specimens fabricated by various forming conditions were carried out and the results were compared according to the forming conditions to find the appropriate condition for the forming composite bone plates. From the tests it was found that the most appropriate forming conditions were $230^{\circ}C$, 3MPa. Composite bone plates were formed using this condition by two different fabricating methods for screw holes: one was a net shape molding and the other was drilling. The forming and bending tests revealed that the drilling process provided much better bending stiffness of bone plates. This paper provided the most appropriate condition for forming composite bone plates and this result was also expected to offer informative data on forming of other Twintex structures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.91-97
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• 2006

This paper presents the results of push-out test conducted for the perfobond rib shear connectors welded onto steel-concrete composite deck. Push-out test specimen consists of profiled steel sheeting, perfobond rib, reinforcement, and concrete. To provide longitudinal shear resistance between the profiled sheeting and the concrete, perfobond rib with a number of holes was used. The parameters considered in the design of perfobond rib were the spacing and location of holes, and effect of reinforcing bars placed in the holes. To validate the effectiveness of the proposed system, twelve specimens were fabricated and tested. Although the scope of test was limited in nature, the results of test have shown that the perfobond ribs can be effectively used for shear connection in the steel-concrete composite decks.

• Proceedings of the ESK Conference
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• 1997.04a
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• pp.331-335
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• 1997

'인체공학적 학생용 책상과 의자 개발(김정용, 1996)'에 관한 연구에서 제작된 1차 시제품을 면밀히 재평가한 결과, 책상 상판의 상하 탄력으로 인한 안전성, 파이프 처리 기술과 높이 조절의 용이성, 한 호수의 의자로 초등 학생부터 고등 학생까지 만족시키지 못하는 신체 적합도 등의 보완점이 제기되었 다. 이를 해결하기 위해 1차 시제품에서 추구하고자 했던 인체공학적 설계 요소를 유지하면서 재료역 학적인 요소와 파이프 가공 기술 등을 고려하여 개선안을 제시하였다. 책상의 무게중심이 중앙에 위치 하도록 다리를 안쪽으로 이동시켜 상판의 흔들림을 방지하였고, 파이프 사이에 삽입된 PVC와 열쇠 모 양의 조립 구멍, 특수 설계된 나사로 조절이 용이하고 고정성과 안전성이 향상되었으며, 파이프 용접 방식으로 넓은 범위의 신체 특성을 포함할 수 있게 되었다. 의자는 초등 학생용과 중.고등 학생용으로 나누어 2호로 설계하였고, 좌판의 곡면을 보다 완만하게 디자인하여 Lumbar와 오금 부위의 압박을 최 소화하였다. 이 외에도 좌판 밑부분에 보조 서랍을 두어 수납 공간의 부족 문제를 해결하였으며, 등받 이에 손잡이용 구멍을 뚫어 이동 시 편의를 제공하였다. 다양하고 세심한 평가 결과를 바탕으로 세부 설계를 완성하였고, 개선된 2차 시제품은 신체 적합도가 더욱 향상되고, 기능성과 편이도가 증대되어 초.중.고등 학생용 교구로서 학생들의 건강한 신체 발달과 학습 의욕 증가 및 중소기업의 이윤 향상 이 기대된다.

• Journal of Life Science
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• v.23 no.4
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• pp.554-559
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• 2013

Brown rice (Oryza sativa) is rich in nutrients, including dietary fiber, vitamins, minerals, and other unmeasured constituents, as well as carbohydrates. Brown rice is an applicable staple for chronic diseases, such as diabetes and hyperlipidemia, but it is not commonly used in dietary management due to several reasons. In this study, we investigated the possibility of using digestive enzymes to process brown rice. When the weight of the brown rice was measured after packing in the same volume of water, it was increased in pectinase-treated brown rice compared to control or collagenase-treated brown rice. Using SEM analysis, we observed huge scratches and nanopores on the surface of the brown rice after the pectinase treatment, but the nutritional components were preserved. We also analyzed the water adsorption rate and performed a starch reaction assay to examine the physical changes after the pectinase treatment. The pectinase-treated brown rice showed a higher water adsorption rate and a faster starch reaction than the nontreated brown rice. These results suggest that digestive enzymes like pectinase can aid the nutritional preservation of brown rice and improve its taste.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.4
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• pp.39-45
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• 2010

Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. The purpose of the present paper is to predict the accurate residual stress of SCM440 high strength steel using the Kendall model which was adopted by ASME Code. Hydraulic pressure process was applied in the inner part and thick-walled cylinders were autofrettaged up to 30% overstrain levels. Electro polishing on the surface of autofrettage specimen was performed to get more accurate residual stress. Residual stresses were measured by X-ray diffraction method. The autofrettage surface which was plastically deformed analyzed using a scanning electron microscope(SEM). Although there were some differences in measured residual stress and numerical results, it has a tendency to agree comparatively with each other.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.46-52
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• 2009

Drilling operation is such an important machining process, which has been wildly applied to the industry, occupied over 30% of whole industry. However, there are many aspects of drilling process should be improved, such as increases of thrust force, surface roughness, and roundness, ect. In this study, we are aiming to reduce the thrust force, surface roughness, and roundness in drilling process. For this purpose, multi facet drills (MFD) of three types that are modified from standard drill (STD) are developed. The first type is multi stair drill (MSD) with shape of stair on relief plane. The second type is rough facet drill (RFD) with shape of round on relief plane. The third type is rough flute drill (RFLD) with shape of round on flute plane. For three types of MFD, we were carried out performance evaluation from the perspective of thrust force, surface roughness and roundness of machined hole. From obtained result, we could confirmed that performance of rough flute drill (RFLD) type is most excellent.