• 한국건설관리학회논문집
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• 제4권4호
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• pp.173-181
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• 2003

기성 콘크리트 파일(PHC파일)은 대규모 건축공사 및 토목공사에서 주로 사용되며, 최근 건축물이 중량화, 대형화, 고층화됨에 따라 그 수요가 지속적인 증가 추세에 있다. 이와 같은 PHC파일은 건물 구조체의 기초와 연결되어 지지력을 확보하기 위해 두부정리 작업이 반드시 요구된다. 두부정리 작업은 800$\cal{kg}f/cm^2$이상으로 압축된 기성 콘크리트 파일의 두부를 파쇄하고 약 30-40cm 정도의 강선을 남겨놓아 구조체의 기초와 정착시킬 수 있도록 하는 작업이다. 국내 재래식 두부정리 작업은 노동 집약적이면 노무자간의 숙련도 차이에 의해 품질 및 작업 생산성이 크게 영향을 받고 있다. 또한, 백호에 연결된 크러셔에 의한 무리한 작업으로 인해 PHC파일 그라인딩면에 다량의 균열이 발생됨으로써 구조체의 지지력 확보에 문제점이 있는 것으로 분석되었다. 따라서 본 연구에서는 재래식 두부정리 작업의 문제점을 해결하고 두부정리 작업을 자동으로 수행학 수 있는 자동화 장비를 개발하고자 기존 문헌 고찰 및 국내외 치신기술 동향, 현장조사를 바탕으로 개념디자인을 제시하고 두부정리 자동화 장비의 파일롯타입을 제작$\cdot$실험함으로써 제안된 개념 디자인의 기술적 타당성 제시 및 자동화 장비 개발을 위해 요구되는 설계파라미터를 도출하였다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.578-585
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• 2000

Geometrical characteristics of fresh red pepper(Capsicum annuum L.) were measured and indexed to define some important geometrical characteristics, and malformation of body and fruit stalk which are necessary for the design of the equipments for cutting, spreading and alignment of red pepper in developing a fruit stalk remover of fresh red pepper. The effects of bending of body and fruit stalk on the equipments of cutting, spreading and alignment were studied. The maximum lengths of some parts of fresh red pepper were found to be 180 mm, 125 mm, 144 mm, 67 mm and 76 mm for the body, the bent part of body, the fruit stalk, the bent part and the straight part of fruit stalk, respectively. The fresh red pepper with bending indices more than 0.4 and 0.3 for the body and the fruit stalk, respectively, was defined to be malformed based on the result of cutting rate using cutting unit; while the other ones to be normal in shape. Based on this, among the total fresh red peppers tested, 47%, 40% and 20% were found malformed for the body, the fruit stalk, and for both of the body and the fruit stalk. Malformed red peppers were poorer in spreading and alignment than normal ones, and the processed quantity was decreased with increased feed rate. The required time for the malformed peppers to pass on the alignment plate inclined at 30 increased rapidly at 8.3 Hz with increased feed rate. For the fresh red peppers with average moisture content of 85%,w.b., the maximum tensile strength between fruit stalk and body was 88.1 N; the maximum cutting resistances were 92.1 N and 94.9 N for the fruit stalk-calyx joint and body, respectively. Average coefficients of static friction were 0.99, 0.62, 0.59 and OJ, respectively, for the surfaces of rubber, galvanized iron, acryl and plywood.

• 한국지반환경공학회 논문집
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• 제19권10호
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• pp.27-34
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• 2018

원호활동파괴가 발생한 해안 폐기물 매립장에서 기초지반 전단강도의 보완과 폐기물 침출수가 지하수나 인접지반으로 유동되는 것을 차단하는 최종 시설로서 시멘트계 지중벽체를 시공한 후, 침출수 차단효과를 확인하였다. (1) 육안 확인 및 (2) 압축강도 시험에 의하면 지중에 시공된 벽체의 품질이 상당히 양호하다는 사실을 확인할 수 있고 (3) 현장 투수시험과 (4) 성분 및 성분비 분석과 (5) 질량 분석기를 통해서 얻게 되는 크로마토그램의 분포패턴 판정 등 중복적인 실험 및 조사 분석에 의해서 벽체의 수밀성이나 침출수의 이동에 대한 차단성이 매우 크다는 것을 확인할 수 있었다. 따라서, 폐기물 매립장 내에서 발생하는 침출수와 같은 고농도 환경오염수가 매립장 밖으로 유출되거나 침투하는 것에 대한 신뢰적인 차단 여부는 이 5가지의 조사 및 시험을 실시하는 방안에 의하여 객관적으로 판단될 수 있다고 사료된다.

• 한국표면공학회지
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• 제41권6호
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• pp.335-340
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• 2008

Cutting performance and wear behavior were studied with the diamond micro-blade of Cu/Sn bond materials containing various amount of lubricant materials such as graphite and $MoS_2$. Measurement of instantaneous electric power consumption for cutting glass workpiece at the constant velocity was conducted and proposed as a method to assess cutting efficiency. The energy consumption of micro-blade for glass cutting decreased with the content of graphite and $MoS_2$ while wear amount of blade in volume increased with the amount of lubricant addition during the dicing test. It is because that hardness, flexural strength, and fracture toughness ($K_{IC}$) reduced with the amount of lubricant addition. Blades with $MoS_2$ additive showed higher mechanical properties than those with graphite additives when the same amount of the lubricant additive in wt.% was added. Due to the lower density of graphite than $MoS_2$, higher volume fraction of graphite could result in stronger effect on lowering electric power consumption by reducing the friction between blade and work piece however increasing wear rate due to the reduction in strength and fracture toughness. Adhesive wearing mode of micro blade could be remarkably improved by the addition of graphite as well as $MoS_2$.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.364-369
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• 2002

The purpose of this paper is to introduce the concept design and the structural strength of the double-deck rolling stock vehicle. Aluminum is very useful material for the carbody structure due to its characteristic of light weight. Large alumillum extrusion profiles(panels) have toe of merits such as easy production of complicated shapes, reduction of welding and cutting lines, and cutting down the labor cost. AED type is being applied to the standard EMUs and the EMUs Kwangju subway in Korea. Light material recommended the double-deck rolling stock vehicle because the center of gravity of the train is higher and its weight is heavier than those of the normal vehicle. So we applied the technology of the large aluminum extrusion profiles(panels) to the double-deck vehicle. We performed the structural strength analysis and examined its safety.

• 한국세라믹학회지
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• 제31권2호
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• pp.177-184
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• 1994

AlN-BN ceramics with BN contents in the range of 10 to 40 wt% were prepared by hot pressing using no additive, or 3 wt%, Y2O3 or CaO, which are common densification aids for AlN. And their machinability, bend strength, and microstructures were investigated. Both the main and radial cutting forces decreased with increasing BN content in all three kinds of samples. For the BN contents of 30 wt% or above, the cutting forces were lower than that of a mild steel tested at a same condition. Especially in the case of main forces, the values were less than a quarter of that of a mild steel, indicating excellent machinability. Bend strength (when the tensile surfaces of specimens were perpendicular to the hot pressing direction) also decreased with BN content mainly due to the much lower Young's modulus of BN compared to AlN. With the composition of 30 wt% BN at which the AlN-BN ceramics started to show better machinability than a mild steel, the bend strength was 150 to 160 MPa, which is greater than that of machinable glass-ceramics of a mica system. With tensile surfaces parallel to the hot pressing direction, however, the bend strength obtained for the samples processed with the sintering acids showed low values (about 40 MPa), since most BN particles had such orientation that their cleavage planes (i.e., basal planes) were perpendicular to the pressing direction.

• Steel and Composite Structures
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• 제6권6호
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• pp.531-555
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• 2006

H-shaped welded steel column members are fabricated by welding together pre-cut flanges and the web. Modern fabricators are increasingly using plasma-cutting technique instead of traditional flame cutting. Different fabrication techniques result in different degrees of geometric imperfections and residual stresses, which can have considerable influence on the strength of steel columns. This paper presents the experimental investigation based temperature profiles, geometric imperfections, and built-in residual stresses in plasma cut-welded H-shaped steel column members and in similar flame cut-welded H-shaped steel columns. Temperature measurements were taken during and immediately after the cutting operations and the welding operations. The geometric imperfections were established at closely spaced grid locations on the original plates, after cutting plates into plate strips, and after welding plate strips into columns. Geometric imperfections associated with plasma cut element and members were found to be less than those of the corresponding elements and members made by flame cutting. The "Method of Section" technique was used to establish the residual stresses in the plate, plate strip, and in the welded columns. Higher residual stress values were observed in flame cut-welded columns. Models for idealized residual stress distributions for plasma cut and flame cut welded sections have been proposed.

• 한국정밀공학회지
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• 제25권3호
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• pp.56-62
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• 2008

The biocompatibility and the fatigue strength of Co-Cr-Mo alloy are excellent, so it is used well for the material of artificial joints. The head of artificial joint needs mirror surface for reduction of abrasive resistance. Mirror finishing of Co-Cr-Mo alloy with geometrically defined single crystal diamond cutting tools is handicapped by micro chipping of tool edge. In general, it is said that the micro chipping of diamond tool is caused by work hardening of Co-Cr-Mo alloy for the cut. In the present research, mirror finishing of Co-Cr-Mo alloy by applying ultrasonic elliptical vibration cutting was carried out. The experimental results show that the micro chipping of diamond tool was suppressed and the tool wear was remarkably reduced as compared with the ordinary diamond cutting without elliptical vibration motion. It was confirmed that the good mirror surface of maximum surface roughness of 25 nmP-V was obtained for the cutting length of about 14 m. It is expected that mirror finishing of Co-Cr-Mo alloy can be achieved by applying ultrasonic elliptical vibration cutting practically.

• 한국기계가공학회지
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• 제18권11호
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• pp.76-82
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• 2019

This study aims to find the shapes of an end-mill with low cutting temperature during the end-mill process of Ti-6Al-4V alloy. Such ${\alpha}-{\beta}$ titanium alloys are increasingly more used for their high tensile strength and high corrosion resistance. The cutting characteristics of Ti-6Al-4V alloy were studied using an analytical method validated by comparing the estimated cutting resistance with that from experiments. The end-mill shape was analyzed using an experimental method. The end-mill shape with low cutting resistance and low cutting temperature was confirmed by analyzing the signal-to-noise ratios for various conditions. Then, the factors with significance factor of 95% or more were determined in the variance analysis. Finally, an end-mill shape that can ensure a low cutting temperature was proposed.

• 한국산업융합학회 논문집
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• 제5권3호
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• pp.201-208
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• 2002

The machine tool which operates by hand is replacing by CNC machine tool to improve the quality of the product and the productivity in modem mechanic industry. The precision of machine part is influenced greatly the surface roughness by cutting condition of machine tool. So this study was performed to examine the aluminium surface roughness of section according to change of strength rating, nose radius, cutting speed, using live center. The results of this study are as follows; 1. In the case of 56mm diameter of test piece(length is below triple of diameter), whether establish the live center or not, doesn't influence to the surface roughness, and it is possible to make product without the live center. 2. The average surface roughness of 42mm diameter(length is quadruple of diameter) is similar to the 56mm diameter in the cutting condition of nose radius 0.8mm and cutting speed 140mm/min, but there are increases and differences in other cutting conditions. 3. In the case of test piece length more 70m/min(140m/mm) and nose radius improved greatly using the live center. 4. In the case of test piece length is quintuple of diameter, the nose radius must choose big tool and increase the cutting speed in preference live center establishment availability to improve that is surface roughness. Conclusively, if aluminum test piece length is fewer than triple of diameter, can process without establishing live center. If aluminum test piece length is more than quintuple of diameter, cutting conditions to improve surface roughness are (1) cutting speed (2) nose radius (3) whether the live center uses or not.