• Journal of Biosystems Engineering
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• 제8권1호
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• pp.17-29
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• 1983

The milling process is considered as causing one of the greatest grain losses among all the processes in rice post-production. Major source of grain losses in the rice milling is considered as the whitening process. This study was attempted to develop an abrasive-type whitener, the whitening chamber of which being supplied by jet-air evenly and continuously. To investigate the milling performance by the new whitener, three kind of emery-stone grit(#36, #41, and #46), and three levels of rotational speed of emery stone roller (950, 1070, and 1200 rpm) were tested. The jet-air abrasive-type whitener was also compared with the conventional abrasive-type having no jet-air blower in terms of their milling performance. In addition, the effect of different combinations of sequential uses of the abrasive- and friction-type whiteners on the milling performance was also experimentally evaluated. The results of this study are summarized as follows; 1. In general, the whitening system combined with the abrasive type whitener with jet-air supply, which was newly designed, and the existing jet-air friction type whiteners produces more milled- and head-rice by about 0.3% points and 2.8% points, respectively than the system combined with the existing abrasive type without the jet-air supply under the same operational conditions. The former also consumed less electricity by 0.024 KwH per 100kg of milled rice production and gave more milling capacity by about 35 kg/hr. As compared with the conventional whitening system consisting of jet-air friction type whiteners only, the former yielded more milled- and head-rice by 1.5% points and 4.4% points, respectively. 2. The abrasive roller having 46 grit emery was better than the roller having 36 grit in aspects of milling performance and machine efficiency, in general. 3. With regard to the effect of combination method of abrasive type and friction type whiteners, one pass in abrasive type plus three passes in friction type gave better milling performance and energy efficiency than the two passes in abrasive type plus two passes in friction type regardless of the designs of the emery stone rollers. 4. The increase in rotational speed of the emery stone roller from 950 rpm to 1200 rpm presented negative effects on milled and head-rice yields and machine efficiency, but slightly positive effect on milling capacity.

• 소성∙가공
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• 제22권2호
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• pp.80-85
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• 2013

The surface integrity of micro-machined products affects the performance of products significantly. Micro-burrs resulting from micro-cutting degrades the surface quality. Therefore it is desired to eliminate them completely and many studies have been undertaken for this purpose. In this study, micro-end-milling was carried out on nickel alloy and brass materials commercially used for light guide plate mold in 3-D optical devices. After completing this micro-machining, the burr heights were measured with a microscope. Then, deburring was done on the machined edges using the MR jet polishing method. A jet angle of $0^{\circ}$ and deburring times of 1, 3, and 5 min. were chosen. It was found that burrs were completely eliminated after 5 min of MR fluid jet polishing.

• Journal of Biosystems Engineering
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• 제7권2호
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• pp.72-85
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• 1983

Rice whitening is performed by basically two different whitening actions known as abrasive and frictional. The former adopted in the emery stone abrasive type whiteners and the latter in the jet-air friction type. Comparative milling yields and whitening efficiencies between the whitening system consisting of jet-air friction type whiteners only and the system consisting of both abrasive- and jet-air friction-types have not yet been rigorously defined. This study was to examine the effect of combined operations of abrasive- and jet-air friction-type rice whiteners on milling yields and whitening efficiencies. The small capacity commercial units of the abrasive- and friction-type whiteners were used for the experiments. The combinations of whitening treatments were: 1) Once in the abrasive type and then two to three times in the friction type, 2) twice in the abrasive and then two to three times in the friction type and 3) three to five times in friction type. In these tests, counter pressures for the friction type whiteners were established differently as required to get about the same degree of whitening at the end of predetermined numbers of the repeated operations. The speed of emery stone and the slot angle of the screen were also the factors varied in the abrasive type whitener. Sheukwang rice variety having 13.05% M.C. was used in the tests. The dependent variables were the milled- and head-rice recoveries and electricity consumption. The results of the study are summarized as follows: 1. It was found that in the whitening systems consisting of abrasive- and friction-type whiteners slot angle of the screen, the rotational speed of emery stone roller had significant effect on the milling yields and whitening efficiency. In general, the increase of the emery stone roller speed from 690 to 950 rpm presented a positive effect on milling yield, and one-pass abrasive milling combinations had higher milling yields than two-pass abrasive milling combinations. 2. It was apparent that if the slot angle of the screen and the speed of emery stone roller are modified and set at an optimum level, the combination whitening system consisting of abrasive- and friction-type whiteners is better than the pure frictional whitening system consisting of jet-air friction type in terms of milling yields and efficiencies. 3. In the rice whitening system consisting of abrasive- and jet-air friction-type whiteners, the best whitening performance was obtained when the slot angle of the screen and the rotational speed of emery stone roller were $45^{\circ}$ and 950rpm, respectively, for the one-pass abrasive milling combinations. However, for the two-pass abrasive mi11ing combinations, the best performance was obtained with $75^{\circ}$ of slot angle and 950 rpm of the emery stone roller speed. 4. As compared with pure frictional whitening systems, the combination systems produced more milled rice by 0.8-1.0% point and more head rice by 0.5-1.5% point, and consumed less electricity by 0.15-0.20 KwH per 100kg of milled rice when the abrasive whiteners were operated in the modified conditions as described in item 3 above. Further study is recommended to find out optimum operational and design conditions of abrasive type whiterners.

• 한국식품과학회지
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• 제38권6호
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• pp.751-755
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• 2006

본 연구에서는 제분기, 건조방법별 등 다양한 조건별로 흑미쌀가루를 제조하여 각 쌀가루별 품질특성을 조사하였다. 건조조건에 다른 roll mill로 제분한 흑미쌀가루의 수분함량은 열풍건조 10.3% 마이크로파 건조 14.4%로 측정되었다. 대조구인 백미쌀가루의 수분함량은 10.0%였다. Jet mill 분쇄 후 쌀가루의 수분함량은 7.5-7.9%로 roll mill 분쇄 후 수분함량 보다 낮은 수분함량을 보였다. WAI는 0.32-0.45로 차이를 나타내지 않았으나, WSI는 입자크기가 작은 jet mill로 분쇄한 흑미쌀가루가 7.3-16.3%로 높았고, 입자크기가 큰 roll mill 분쇄한 대조구와 흑미쌀가루가 각각 0.7, 3.7, 4.1%로 낮은 값을 나타내어 입자크기가 감소함에 따라 증가하였다. 입자크기가 작을수록 L값은 증가하였고, a값은 감소하였다. Jet mill로 분쇄한 모든 흑미쌀가루의 평균입도는 건조조건, 침지조건에 상관없이 39.1-41.5 ${\mu}m$로 유사한 입도분포를 나타내었으나 초미세 흑미쌀가루의 평균입도는 9.4 ${\mu}m$로 가장 작은 입도분포를 나타내었다. 대조구인 백미가 6.3 mg/100 g으로 가장 낮고, 흑미쌀가루는 91.4-115.8 mg/100 g으로 유사한 값을 보였다. 제분방법에 따른 흑미쌀가루 총 아미노산 함량은 74.9-96.4 mg/100 g으로 측정되어 백미 쌀가루 총아미노산 30.5 mg/100 g 보다 약 3배 높은 함량을 보였다. 결과적으로 가공제품으로 흑미쌀가루 이용시 건조방법 보다는 제분방법 즉 입도분포가 흑미쌀가루에 품질특성 변화에 더 영향을 주는 것으로 판단된다.

• 한국생산제조학회지
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• 제25권1호
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• pp.83-88
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• 2016

Because of the increasing tool cost for cutting hard-to-cut materials, abrasive water jet (AWJ) milling recently has been regarded as a potential alternative machining method. However, it is difficult to control the depth and width of cut in AWJ milling because they vary depending on many AWJ cutting parameters. On 27 conditions within a limited range of pressure, feed rate, and abrasive flow rate, AWJ cutting was conducted on titanium, and depth profiles were measured with a laser sensor. From the depth profile data, depth and width of cut were acquired at each condition. The relationships between depth and parameters and between width and parameters were derived through regression analysis. The former can provide proper cutting conditions and the latter the proper pick feed necessary to generate a milled surface. It is verified that pressure mostly affects depth, whereas abrasive flow rate mostly affects width.

• 한국식품과학회지
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• 제25권5호
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• pp.546-551
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• 1993

제분방법별(Pin mill, Colloid mill, Micro mill, Jet mill)로 제조한 쌀가루의 특성과 쌀 수제비 제조후 식미에 미치는 영향을 조사하였다. 지방, 회분, 단백질은 제분 방법에 따라 큰 차이를 보이지 않았다. 제분방법별 쌀 가루의 청값, 열수가용성 아밀로오스 함량, 그리고 전분 손상도는 Jet mill, Micro mill, Colloid mill, Pin mill의 순으로 높았음을 나타내었다. 수분흡수지수, 수분용해지수 및 보수력을 측정한 결과 전분손상도가 증가함에 따라 전체적으로 증가하였다. 또한 시료농도 15%의 겔을 형성하였을 때 Pin mill의 경우 강도에 있어서 가장 높음을 보여주었다. 아밀로그램을 이용한 호화개시온도와 최고점도는 입자가 미세하여 짐에 따라 점차 낮아지는 경향을 보였으며 Differential Scanning Colorimetry 측정에 의한 측정값도 아밀로그램에서와 동일한 양상을 나타내어 호화흡열의 면적에서 산출한 호화엔탈피$({\Delta}H)$가 Jet mill의 경우 0.83 kcal로 가장 낮았다. 즉 전분의 손상도가 증가함에 따라 호화엔탈피는 감소하였다. 쌀수제비 제조실험 결과는 Jet mill이 관능검사 결과 가장 우수한 것으로 판명되었고 반죽상태도 양호함을 보여주었다.

• 한국생산제조학회지
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• 제25권2호
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• pp.118-123
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• 2016

Overlap cutting is a fundamental method of applying abrasive water jet (AWJ) machining to milling to produce a wider surface because the nozzle outlet is approximately 1.0 mm wide. In this study, the effects of overlap cutting on the depth profile and surface roughness are investigated. The overlapping area depends on the amount of step over, which is controlled in the pick-feed direction. If the step over is equal to or larger than the diameter of the nozzle, no overlap cut occurs but large cusps remain between the cut paths. A step over as small as one-thirds of the nozzle diameter may lead to triple-overlap cutting resulting in an extraordinary depth. By using pocket milling experiments with a step over of 0.46 (or 0.47), it is verified that AWJ can produce a milled surface of titanium, one of the hard-to-cut materials, with $76{\mu}m$ Ra.

• 한국염색가공학회지
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• 제15권5호
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• pp.321-326
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• 2003

In order for disperse dye based ink to be fitted with the critical requirements of ink jet printing, this study was undertaken to investigate the effects of 6 different dispersants on the milling efficiency of insoluble dye particles and dispersion stability of the final ink. It was found that a polystyrene dispersant with high molecular weight exerted relatively better dispersion stability which may be associated with its steric stabilization effect in the ink solution.

• 한국식품조리과학회지
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• 제29권6호
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• pp.741-747
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• 2013

This study was carried out to investigate the quality characteristics of roll mill, jet mill Hericium erinaceus (HE) powders and seasonings using them (RPS and JPS). Water binding capacity of the jet mill HE powder(JP) was higher than that of roll mill HE powder(RP). The reduction of particle size resulted in the increases of specific surface area and JP showed smaller particle size than RP. $L^*$ of JP was significantly higher than that of RP. In sensory evaluation, the color and the flavor of seasoning showed on significant difference. Control and JPS got significantly high scores in 'Overall Acceptability' than RPS. Based on the results in this study, JPS is considered to have potential to be developed commercially as seasoning.

• 한국식품과학회지
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• 제25권5호
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• pp.541-545
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• 1993

Sieve shaker와 Elzone particle size analyzer에 의한 두 가지 방법으로 제분방법에 따른 입자크기를 조사하였다. 제분방법별로 제조한 쌀가루의 입도분포를 측정한 결과 입자크기는 제분방법에 따라 영향을 받았으며 표준망체를 이용한 Sieve shaker 방법보다 Elzone particle size analyzer를 사용한 방법이 정확도가 우수하였다. 입도분포를 측정한 결과 Pin mill의 경우 $200{\sim}270$mesh가 30.38%으로 가장 많았고 $60{\sim}500mesh$의 분포도를 가졌다. Colloid mill은 $140{\sim}200mesh$가 가장 많았으며, $40{\sim}500mesh$의 분포도를 가졌다. Micro mill은 500mesh 이상이 41.62%로 가장 많았고 $140{\sim}500mesh$의 분포도를 보여주었다. Jet mill은 500 mesh 이상의 분포도로 입자크기가 가장 미세하였다. 또한 미세한 입자일수록 L간과 a값이 증가하였다. 쌀가루의 집합체를 살펴본 결과 습식제분은 분리된 쌀가루의 집합체형태로 구성되어 있고 건식제분은 분활된 조직체로 구성되었다. 전자주사현미경은 Elzone particle size analyzer 방법과 같은 입자분포도를 나타내었고 제분방법에 따라 구조의 특성을 보여주었다.