• Journal of Welding and Joining
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• 제15권1호
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• pp.116-124
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• 1997

A scope of this study is to establish the optimum plasma spray conditions for fine ($5\mu\textrm{m}$) $Al_2O_3$ powder. However, the flowability of the $Al_2O_3$ powder is not so good because of irregular particle shape and fine particle size. Therefore, powder feeding system was modified by 1) change of powder feeding line material from polymer to copper 2) shorten the powder feeding tube length 3) heating the powder feeding system to $80^{\circ}C$4) vibrating the powder feeding line continuously, in order to feed the fine powder homogeneously. The homogeneous powder feeding conditions were obtained with the modified powder feeding system by controlling the powder carrier gas flow and the powder flow rate indicator. The best plasma spraying conditions for the fine $Al_2O_3$ powder were found out as 40kw gun power, 80 g/min. powder feed rate and 50 mm working distance after characterizing the microstructure, hardness and wear loss of the $Al_2O_3$ coating layer.

• Journal of Welding and Joining
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• 제31권4호
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• pp.13-16
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• 2013

In this research, laser cladding characteristics were investigated for various filler metal feeding methods such as powder, cold wire, and hot wire feeding. Appropriate parameter window, deposition rate, material efficiency and dilution for each filler feeding method were evaluated with same laser power and cladding speed range. Laser powder cladding has wider process parameter window but higher material efficiency and lower dilution were achieved by laser wire cladding. Among these feeding methods, laser hot-wire cladding showed best efficiency in material usage and deposition rate.

• Journal of Welding and Joining
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• 제35권3호
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• pp.28-34
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• 2017

The authors derived the criteria on the process parameters of laser depositions with metal powers(SUS316L & IN718) by evaluating the surface and cross-section properties of the deposition layers. The surface characteristics of the deposition layer are investigated through optical microscopy by controlling the process parameters of laser output, powder feeding rate and gas feeding rate. The cross-section characteristics were also analyzed after polishing and chemical etching process. As the gas feeding rate increased, the amount of powder loss increased and the difference in the dilution ratio and heat affected zone depending on laser outputs was observed. In addition, the powder feeding rate used in the experiment did not interfere with the energy absorption of the base material.

• Journal of Nutrition and Health
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• 제19권1호
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• pp.16-22
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• 1986

This study was designed to investigate the nutritional effect of mugowrt powder supple mentation to rice diets with different protein levels. Thirty female albino rats weighing 39-43g were adopted for the feeding trial for 4 weeks. The different 5 kind of experimental diets were performed . Control diet was commercially available forage for rats, experimental diet (I-C) highly milled rice, (Ⅰ) highly milled rice 95% and mugwort powder 5%, (Ⅱ-C)highly milled rice 95% and milk casein 5%, and (Ⅱ) highly milled rice 90%, milk casein 5 % and mugwort powder 5%. Growth rate was remarkably high in the dietary group fed on highly milled rice supplemented with 5% mugwort powder (protein 8%) (P<0.05), but it showed the tendency to be rather low in the group fed on highly milled rice supplemented with 5% casein and 5% mugwort powder (protein 12%). Food efficiency as well as protein efficiency appeared similar to the growth rate. Hematodcrit level demonstrated the same tendency as growth rate, but hemoglobin content was observed to increase by diets supplemented with increasing amount of mugwort regardless of protein level. Each nutrient intake was increased by adding mugwort powder to diets after a week's feeding, but it was increased by 8% protein diet, and decreased by 12% protein diet in 3 weeks as well as 4 weeks after feeding . The absorption rate of carbohydrate and protein decreased by feeding mugwort supplemented diets regardless of protein level and feeding period, and that of lipid increased with 12% protein diet.

• Journal of Welding and Joining
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• 제15권4호
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• pp.109-115
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• 1997

Laser cladding is a technique for modification of metal surface. In this laser cladding experiment a metal powder feeding system was developed for more efficient laser cladding. This system can reduce processing time and be used simpler than the conventional method. The feeding of metal powder has given a rise to the process for sequential buildup of bulk rapidly solidified materials in the form of fine powder stream to the laser cladding process. The parameters of laser cladding have been investigated using this experimental equipment. Bronze on aluminum alloy and copper on aluminum alloy were experimented by using defocused beam, powder feeding system, and gas shielding. Good cladding was achieved in the range of beam travel speed of 2.25m/min. In the case of copper/aluminum and bronze/aluminum substrate, the absorption of laser beam was too high to produce low diluted clad. In the case of copper/1050 aluminum, the optimal laser cladding condition was of laser power of 2.8kW, powder feed rate of 0.31g/s and beam travel speed of 2.25m/min. In the case of bronze/aluminum the optimal condition is of laser power of 2.5kW, powder feed rate of 0.31g/s, and beam travel speed of 2.36m/min.

• Journal of Welding and Joining
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• 제11권2호
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• pp.74-85
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• 1993

Effect of Si metal powders addition with the plasma transferred arc(PTA) overlaying process on characteristics of the alloyed layer in aluminum alloy(A5083) has been investigated. The overlaying conditions were 175-250A in plasma arc current, 500mm/min in travel speed, the 5-20g/min in powder feeding rate. Main results obtained are summarized as follows. 1)Sufficient size of molten pool on surface of base metal was required for forming an alloyed layer; in a fixed travel, the formation of alloyed layer with clear and beautiful surface depend upon the plasma arc current and powder feeding rate; the greater plasma arc current and the smaller powder feeding rate were, the better bead was formed. Optimum alloyed conditions by which an excellent alloyed bead obtained was 225A in plasma arc current. PTA process made it possible to form an alloyed layer with up to 67wt% Si. 2)Microstructure in the alloyed layer was in accord with prediction from the Al-Si phase diagram 3)The hardness of the alloyed layer increased in proportion to Si content. 4)As volume fraction of primary Si increased, the specific wearness of the alloyed layer was significantly improved. However, no further improvement was found when the volume fraction was greater than about 30%. 5)Utilizing the PTA process, a crack free alloyed layer with maximum hardness of about Hv 310 could be obtained.

• Journal of Welding and Joining
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• 제34권1호
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• pp.35-40
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• 2016

Recent developments of Laser metal 3D deposition with wire feeding are reviewed which provide an alternative to powder feeding method. The wire feeding direction, angle and position as well as laser power, wire feeding rate, and deposition speed are found to be key parameters to make quality deposition with high throughput. When compared with the powder feed, the wire feed shows higher material efficiency, higher deposition rate, and smoother surface. Large elongated columnar grains which have epitaxial growth across deposit layers are observed in deposit cross sections. The growth direction is parallel to the thermal gradient during the deposit process. Tensile properties are found to be dependent on the direction due to the anisotropic deposit property. A real-time feedback control is demonstrated to be effective to improve the deposition stability.

• Journal of Welding and Joining
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• 제14권4호
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• pp.53-61
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• 1996

It was attempted to improve the wear resistance of Al alloy under the load condition by making a formation of the thicker surface hardening alloy layers. The thicker surface hardening alloy layers were formed on 6061 Al alloys overlayed by MIG and TIG welding process with Cu powders feeding. The characteristics of hardening and wear resistance have been investigated in relation to the microstructures of alloyed layers, with a selection of optimum alloying conditions for formation of overlaying layer. The results obtained were summarized as follows With increasing feeding rate of Cu powders by MIG welding, the hardness and specific wear of the overlay weld alloys were increased. It is considered that these high hardness and specific wear of overlay weld alloys were due to the formation of Θ($Al_2Cu$) phases. With increasing feeding rate of Cu powders by TIG welding, the hardness and specific wear of the overlay weld alloys were increased in feeding rates 12 and 18g/min. However, the hardness and specific wear were decreased in the powder feeding rate 38g/min. It is considered that considered that decrease of hardness and specific wear in the powder feeding rate 38g/min due to formation of ${\gamma}$($Al_4Cu_9$) phases.

• Journal of Nutrition and Health
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• 제10권3호
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• pp.33-47
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• 1977

This study was devised to observe the nutritional effect by feeding of rice diet supplemented with Ginseng powder in Albino rats. The male albino rats (84 heads), weghing about 56g, were used for the experimental animals. They were divided into six diet groups; which were the 6.4% protein diet, the 12.8% protein diet and the 17.9% protein diet as the control and each control diet was supplemented with 3% of Korean Ginseng powder as experimental diet. These diet groups were again divided into 2 groups according to the feeding terms, 3 weeks and 6 weeks. The animals were sacrificed after feeding the coresponding diet for 3 weeks and 6 weeks and the liver, heart, kidney, intestine and serum were collected as samples for analysis. The growth rate, efficiencies of protein and food, lipid, cholesterol and nitrogen in the samples were determined. The results obtained are summerized as follows; 1. The growth rate were improved by feeding of the 13% and the 18% protein diet supplemented with 3% ginseng powder than the coresponding control diet group, although the same results were not observed in the 6.8% protein diet groups. 2. The consumptions of the food and the protein in each dietary group were similar to each other. 3. The efficiencies of the food and the protein were improved by feeding of the 13% and the 18% protein diet supplemented with the ginseng powder than each control diet group. 4. The lipid contents in the liver of each expperimental diet group, in the feeding for 3 weeks, were shown the tendency to increase slightly, compared with the coresponding control group, whereas in the feeding group for 6 weeks, the contents were shown rater the decreasing tendency. 5. The total cholesterol contents in the liver of each experimental diet group, in the feeding group for 3 weeks, were maintained slightly higher level than the coresponding control group, whereas in the feeding group for 6 weeks, the contents were shown similar levels. 6. The total cholesterol contents in the heart were maintained with similar level in each diet group and each feeding term.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.405-409
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• 2010

금속분말을 청정 에너지원으로 이용하기 위해 금속분말 소형 연소기의 구현이 필요하다. 이를 위한 선행연구로 연료 공급 시스템인 핀틀인젝터형(pintle injector type) 금속분말 공급장치의 중요 성능인 분사량을 실험적으로 측정하였다. 분사량 측정 시험에 앞서 간단한 금속분말 공급 시험으로 확인된 문제점을 장치의 변경을 통해 해결하였다. 측정 시험의 결과, 연료 공급 장치에 이송 가스 압력이 상승함에 따라 많은 질유량의 금속분말이 분사되었고 압력에 따른 정량적 분사량을 확인하였다. 이송 가스와 금속분말의 혼합 성능을 개선하여 균일한 분사를 하고자 이송 가스를 25 Hz로 가진 하여 공급하였고 가진이 없는 경우의 실험결과와 비교하였다.