• Design & Manufacturing
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• 제7권1호
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• pp.45-49
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• 2013

Since the shell-molds are used to make casting the metal parts for the automobile industry, the quality may well be inconsistent with the lower productivity, increasing the cost of the end products. The primary elbow design shell molded steel castings being produced through extrusion process has $180^{\varnothing}$ O.D., $150^{\varnothing}$ I.D., 14mm thickness and 400mm length, while being processed onto the left side of the tubing. The primary cause for the poor processing is the uneven manual shell molding. If the manual shell molds should be produced to have even quality, they would not be processed for tube linking. The purpose of this study was to develop the flask-molds for manufacturing of the shell molds to ensure mass-production, consistent quality, ommission of processing and comfortable working environment. For this purpose, four flask-molds were produced and thereby, four shell molds were assembled. In particular, the shell molds for processing were formed of the fine coated sand to be blown. As a result, productivity increased about three times, while a consistent quality was ensured. Furthermore, the tubes could be linked with each other without being processed, while pallets could be stacked, stored, transported and managed more easily. In a nut-shell, the molding theory could be applied more effectively. However, it is conceived that this study should be followed up by future studies which will research into reliability and endurability of the end products.

• 대한안전경영과학회지
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• 제15권4호
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• pp.179-184
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• 2013

An accident from machine work is often fatal to the worker. This accident is mostly preventable through perfect process jig. In case of this machine work, however, the disaster frequently occurred because of the design which is not considered the beginning of product design, post-process and mass process of production. As for sand casting method, this has the merits of the production; the product is easily produced by manual labor. On the other hand, this method has the demerits of a bigger dimensional error contrary to other mass process of production. When the sand casting product is in machine work, there are various problems such as unsafe fix and excessive cutting, product desorption and rapid life depreciation of equipment and tools. Considering the characteristics of sand casting method, it is accepted as difficulty to improve the problems. In this study, it suggests shell mold method for mold instead of the machine work after the sand casting of the circle shape container product. And the surface accomplishes the following average of surface roughness Ra$9.94{\mu}m$ of machine work with the casting of flask mold by shell mold method. In accordance with the simplification of processing process and reducing the average thickness variation by mass production of product with detailed appearance, it has a good influence on safety accident prevention caused by production and damaged product. It is confirmed that making higher degree of size precision of all machine work product is possible to increase the safety and productivity, reduce the processing process and improve environment.

• 한국주조공학회지
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• 제22권3호
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• pp.137-143
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• 2002

Silica sand, zircon sand, and steel shots were used as mold packing materials in lost foam casting of the aluminum alloy bar. Vibration acceleration in three directions and temperatures in the casting and mold were measured, and packing and cooling characteristics of these materials were investigated. Packing densities increased with increase in vibration magnitude and time, and were $1.41{\sim}1.49g/cm^2$ for silica sand, $2.54{\sim}2.86g/cm^2$ for zircon sand, and $3.92{\sim}4.52g/cm^2$ for steel shots. Sound castings were obtained only without evacuation of the flask during pouring. Solidification time became faster in order of silica sand, zircon sand and steel shot packing because steel shot has the highest cooling capacity of them. Solidification time of steel shot packing was shortened to about 1/2 of silica sand packing. Cooling capacity of sand mold was generally evaluated by heat diffusivity of the mold, however could be simply evaluated with specific heat per unit volume of the packing material in lost foam casting.

• 한국주조공학회지
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• 제22권5호
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• pp.265-270
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• 2002

A novel jewelry master pattern manufacturing process which reduce manufacturing steps by employing a Duraform rapid prototyping mold and a low melting alloy has been suggested. The novel process follows the steps of 'jewelry 3D CAD design ${\rightarrow}$ Durafrom RP mold ${\rightarrow}$ low melting alloy master pattern' while the previous process follows more complicated steps of 'jewelry idea sketch ${\rightarrow}$ detailed drawing ${\rightarrow}$ wax carving ${\rightarrow}$ flask ${\rightarrow}$ silver master pattern.' An upper and a lower part of molds have been manufactured of Duraform powder, of which melting point is $190^{\circ}C$. A maser pattern was manufactured by pouring a low melting alloy of Pb-Sn-Bi-Cd, so called Woods Metal, of which melting point is $70^{\circ}C$, into the mold. The master pattern is a shape of a disk of 20mm diameter that contains various design factors. The variations of dimensions, surface roughness, surface pore ratio were measured by an optical microscope, a surface roughness profilometer, and a Rockwell hardness tester. The pattern made of were maeasured by an optical microscope, a surface roughness profilometer, and a Rockwell hardness tester. The pattern made of low melting alloy has sufficient surface hardness, and surface pore ratio to be used as the jewelry master pattern.

• 한국주조공학회지
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• 제24권1호
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• pp.34-39
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• 2004

The effects of casting condition and hot melt glue during Lost Foam Casting were investigated on the fluidity of Al alloy melt. The fluidity increased linearly with increasing pouring temperature in thick castings but non-linearly in thin casting due to the difference in main heat flow direction. The metal flow velocity was in range of $0.5{\sim}2.7$ cm/s in no evacuation condition and the minimum value of it was measured after the melt flow through the hot melt barrier. The mold evacuation improved the metal flow velocity by around $0.5{\sim}1$ cm/s. And the reaction zone layer thickness was about 1 cm in no-evacuation conditions but about 0.6 cm in mold evacuation condition of 710 torr due to the easier removal of pyrolsis product of EPS. And hot melt barrier thickness of 0.6 mm increased the reaction zone layer thickness up to about 2.5 cm. The fluidity decreased remarkably with an enlarged thickness of hot melt due to a lot of pyrolysis products.

• 한국균학회지
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• 제27권6호
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• pp.412-414
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• 1999

최근 국내 큰느타리버섯 재배농가가 증가하면서 병해의 발생이 문제점으로 나타나고 있다. 본 연구에서는 큰느타리 버섯의 자실체에 발생하는 푸른곰팡이 병반으로부터 Penicillium sp.균을 분리하여 동정하였고 생리적 특성을 조사하였다. 분리된 Penicillium sp.균의 형태적 특성을 조사한 결과, 분생포자는 타원형이고 크기는 $2.3{\sim}3.4{\times}2.6{\sim}3.2\;{\mu}m$였다. 분생자병은 균사로부터 one-stage branch 모양을 형성하고, metulae는 $2{\sim}4$개로 크기가 $10{\sim}l8{\times}2.5{\sim}3.0\;{\mu}m$이며, phialides는 플라스크상이고 크기가 $9{\sim}13{\times}2.2{\sim}2.8\;{\mu}m$였다. Czapek 배지에서 배양할 경우 $25^{\circ}C$에서 7일에 균총이 21 mm 성장했으며, 균총의 색은 회녹색이었다. 이상과 같은 형태 및 배양적 특징으로 공시균을 Penicillium corylophilum로 동정하였고 이균을 상처접종하였던바 $6{\sim}7$일만에 재배농가에서와 동일한 증상을 나타내었다.

• 한국산학기술학회논문지
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• 제3권2호
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• pp.110-114
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• 2002

주얼리 제조 공정중 마스터패턴 제조 공정은 전체 제조원가의 20%를 차지하기 때문에 매우 중요한 공정이다. 지금까지는 수작업으로 왁스 패턴을 제작하고 이를 이용하여 석고형을 만들고 석고형으로 마스터 패턴을 제작하는 복잡한 공정을 거쳐 제작하였다. 본 연구는 쾌속조형기를 이용하여 듀라폼 재질의 몰드를 만들고 저융점합금을 이용하여 마스터패턴을 직접 제작하는 새로운 공정을 개발하였다. 듀라폰의 용융진이 190℃ 이므로 용융점 70℃의 Pb-Sn-Bi-Cd 계의 저융점 합금을 주물재료로 이용하여 마스터패턴을 제작하였다.

• 공업화학
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• 제9권6호
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• pp.935-941
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• 1998

키토산에 음이온계 수용성의 함인계 모노머인 mono(2-methacryloy1 oxyethyl) acid phosphate를 그라프트공중합시켜 새로운 유도체를 합성하였다. 그라프트공중합의 최적 그라프트율은 개시제농도 $3.5{\times}10^{-3}M$, 모노머농도 0.19 M, 반응온도 $40^{\circ}C$에서 가장 높은 값을 나타내었고, 반응시간 4시간 이후로는 거의 같은 값을 나타내었다. 그라프트공중합체와 chitosan의 유리아민의 함량에 따른 항균성을 Candida albicans, Trichophyton rubrum 및 Trichophyton violaceum에 대하여 shake flask법으로 조사한 결과, pH 5.75에서 가장 우수한 항균성능이 발현되고, 곰팡이 균류에 대한 선택성이 나타남을 확인할 수 있었다.

• 식물병연구
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• 제8권3호
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• pp.184-188
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• 2002

Botrytis cinerea에 의한 들깨 잿빛곰팡이병의 생물학적 방제를 위해 선발한 Bacillus lirheniformis Nl 글주를 제제화하여 미생물농약을 제조하고 이의 방제 효과를 검정하였다. Nl균주의 길항력에 미치는 탄소원과 질소원의 영향을 실험한 결과 탄소원으로는 glucose, 질소원으로는 tryptone이 가장 높은 효과를 보였다. 또한 Nl 균주를 이들 glucose와 tryptone을 첨가한 NB배지에 대량배양하고 그 배양액에 콩가루, 쌀가루, glucose, FeSo$_4$~7$H_2O$ 및 MnCl$_2$. 4$H_2O$ 을 첨가하여 수화형 미생물농약 Soy제제로제조하고,이 병원균에 대한 방제효과를 하우스내에서 폿트 검정한 결과 방제가가 93.1%로서 유의성은 없으나 베노밀 수화제에 의한 86.1%보다 높았다.

• 한국버섯학회지
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• 제5권1호
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• pp.25-28
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• 2007

본 연구에서는 상황버섯 (P. baumii)의 자실체에 발생하는 Penicillium sp.균을 동정하기 위하여, 분리균의 배양적 형태적 특징을 조사하였다. 분리된 Penicillium sp.의 형태적 특성을 조사한 결과, 분생포자의 모양은 타원형이고 직경이 1.8~2.3 ${\mu}m$ 크기로 분생포자를 많이 형성하였다. 분생포자경은 균사로부터 one-stage branch 모양을 형성하였고, matulae는 3~5개로 길이가 5.2~7.8 ${\mu}m$이며, phialide는 플라스크상이고 크기가 $5.7{\sim}7.5{\times}2.2{\sim}2.7{\mu}m$이였다. Czapek's agar 배지에서 생육시 $25^{\circ}C$에서 8일간 균체가 23 mm 생장하였다. PDA 배지 상에서 균총의 형태는 처음에는 조밀한 솜털모양의 백색을 띄었으며 차츰 기중균사가 형성되었고, 점차 회녹색으로 변하였다. 이상과 같은 형태 및 배양적 특징으로 이 균을 P. rubrum으로 동정하였다. 상황버섯 (P. baumii)에서 P. rubrum에 의한 병은 아직 국내에 보고된바 없어, P. rubrum에 의한 상황버섯 (P. baumii) 푸른곰팡이병을 최초로 보고한다.