• 한국분말재료학회지
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• 제10권6호
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• pp.395-405
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• 2003

In the conventional metallothermic reduction (MR) process for obtaining tantalum powder in batch-type operation. it is difficult to control morphology and location of deposits. On the other hand, a electronically mediated reaction (EMR) process is capable to overcome these difficulties and has a merit of continuous process, but it has the defect that the reduction yield is poor. MR-EMR combination process is a method that is able to overcome demerits of MR and EMR process. In this study, a MR-EMR combination process has been applied to the production of tantalum powder by sodium reduction of $K_2$TaF$_{7}$. The total charge passed through external circuit and average particle size (FSSS) were increased with increasing reduction temperature. The proportion of fine particle (-325 mesh) was decreased with increasing reduction temperature. The yield was improved from 65% to 74% with increasing reduction temperature. Considering the charge, impurities, morphology, particle size and yield, an reduction temperature of 1,123 K was found to be optimum temperature for MR-EMR combination process.

• 한국분말재료학회지
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• 제5권4호
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• pp.319-323
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• 1998

Powder forging with a back pressure was investigated for production of automobile and compressor parts made of a rapidly solidified Al-Si alloy powder. Disk-shaped green compacts made of a rapidly solidified Al-Si alloy powder were hot forged, and hubs were formed by loading back pressure on their top. The influences of the back pressure and die temperatures on forgeabiliy and properties of parts made of a rapidly solidified Al-Si alloy powder were examined. This method was also applied to the production of a scroll part. The results of these studies are summarized as follows : 1. A back pressure on the hub top is very effective for consolidation and preventing crack formation in the hub. 2. When a back pressure tess than 98 MPa is applied, the forging pressure increases by the same amount of the applied back pressure. With more than 98 MPa, the forging pressure increases further due to an increased friction at the hub side. 3. Die temperatures higher than approximately 670k are needed in order to consolidate well the hub top without cracks.

• 한국재료학회지
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• 제14권10호
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• pp.719-724
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• 2004

Production of fine tantalum powder by calciothermic reduction of tantalum oxides ($Ta_{2}O_5$) pellet through an electronically mediated reaction (EMR) has been investigated. $Ta_{2}O_5$ pellet feed and reductant calcium-nickel (Ca-Ni) alloy were charged into electronically isolated locations in a molten $CaCl_2$ bath. The current flow through an external path between the feed (cathode) and reductant (anode) locations was monitored. The current approximately 4.7A was measured during the reaction in the external circuit connecting cathode and anode location. Tantalum powder with approximately 99 $mass\%$ purity was readily obtained after each experiment. Tantalum powder by EMR using $Ta_{2}O_5$ pellet feed was fine compared with that of metal powder by metallothermic reduction and EMR using $Ta_{2}O_5$ powder feed.

• Applied Biological Chemistry
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• 제19권4호
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• pp.227-232
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• 1976

고춧가루가 국균(麴菌)의 각종(各種) 효소생산(酵素生産) 및 균체생육(菌體生育)에 미치는 영향을 규명할 목적(目的)으로 Aspergillus oryzae A (단모균)와 Aspergillus oryzae G(장모균) 균주를 고춧가루를 첨가한 밀기울 배지 및 Czapek-Dox 액체배지에 배양하여 그 효소력(酵素力), 건조균체중량 pH. 적정산도 등을 측정한 결과는 다음과 같다. 1. 밀기울 고체배지에 $0.05{\sim}30%$ 농도(濃度)의 고춧가루를 첨가한 구에서는 무염기질(無鹽基質)에서의 중성 및 알카리 protease의 활성이 대조구(밀기울 단독 배양구)에 비하여 높았으나 Aspergillus oryzae G의 경우는 고춧가루 첨가시 무염기질(無鹽基質)에서의 산성 protease의 생성이 오히려 저하 되었다. 2. $0.05{\sim}10%$의 고춧가루 첨가시는 내염(耐鹽)기질에서의 중성 및 알카리 protease의 활성이 대조구에 비하여 높았다. 3. 고춧가루 첨가(添加)는 amylase활성(活性)에 별(別)로 효과(效果)가 없었다. 4. Cellulase활성은 밀기울 단독구에 비하여 고춧가루 첨가구(添加區)에서 전반적(全般的)으로 높은 경향을 보였다. 5. Czapek-Dox액체배지상(液體培地上)에서 각균(各菌)의 건조균체중량(乾燥菌體重量)은 고춧가루 첨가농도(添加濃度)가 증가함에 따라 증가하는 경향을 보였고 단모균은 장모균에 비해 그 증가 현상이 현저하였다. 6. 고춧가루는 Czapek-Dox 첨가배지((添加培地)의 pH를 저하(低下)시키는 경향을 나타내었다. 7. 고춧가루 첨가농도(添加濃度)가 증가함에 따라 Czapek-Dox 액체배지의 적정산도는 증가현상을 나타내었으며 장모균에 비하여 단모균의 경우 적정산도의 증가현상이 현저했다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.221-226
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• 1998

The processing conditions for the mass production of platelet WS$_2$ lubricant powder were optimized. The mixture of tungsten and sulfur powders was sealed in a vacuum of 10$^{-3}$ torr and heat-treated at 850$\circ$C for 2 h. The internal pressure of reaction chamber was maintained at certain level by controlling the release valve automatically. The reaction product was the platelet WS$_2$ powder with an average size of 15 $\mu$m. The synthesized WS$_2$ powder was then coated on the wiper-blade of automobiles and the commercial deep-grooved ball bearing using wet and dry coating methods, respectively. High lubricity and wear resistance of wet coated wiper-blade were confirmed by the life test of 70,000 cycles. The life-time of the ball bearing assembled after WS$_2$ coating onto each part increased 50 times compared to the non-coated ball bearing.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.747-749
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• 2006

SMS Meer GmbH, formerly Mannesmann and today part of the SMS Group, has been building powder presses since the early 1950s. The patents developed here in this field have long since documented the pioneering work carried out for the PM industry. The paper focuses on the challenge of reconciling the contradictory demands in the production of highly complex and crack-free PM parts. The process employed with the patented Controlled Punch Adapter (CPA) [1] counters possible cracking reliably and directly at the source. In this way is it possible to develop new and highly complex parts to series production maturity in a minimum of time even without simulation of the press cycle [2]. The quality data achieved in the production series, almost 100% crack and micro crack-free green parts with optimum density distribution over all press levels is unrivalled and thus gives the user a clear lead over the competition.

• Nuclear Engineering and Technology
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• 제45권7호
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• pp.979-986
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• 2013

Uranium metal particle dispersion plates have been proposed as targets for Molybdenum-99 (Mo-99) production to improve the radioisotope production efficiency of conventional low enriched uranium targets. In this study, uranium powder was produced by centrifugal atomization, and miniature target plates containing uranium particles in an aluminum matrix with uranium densities up to 9 $g-U/cm^3$ were fabricated. Additional heat treatment was applied to convert the uranium particles into UAlx compounds by a chemical reaction of the uranium particles and aluminum matrix. Thus, these target plates can be treated with the same alkaline dissolution process that is used for conventional $UAl_x$ dispersion targets, while increasing the uranium density in the target plates.

• 한국식품영양과학회지
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• 제42권5호
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• pp.828-831
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• 2013

고춧가루 첨가 시기에 따른 사과고추장혼합물에서의 에탄올 생성과 고추장 제조 후 관능검사를 실시하여 사과고추장의 가능성을 검토하고자 하였다. 고춧가루 첨가 전의 사과고추장혼합물에서 효모의 생육은 발효 5일 후 약 6.5 log CFU/ g으로 빠른 증식을 보였으며, 에탄올 생성 농도는 발효 15일 후 3.8%에 도달하였다. 고춧가루를 미리 첨가한 사과고추장혼합물의 경우에 효모균주의 생육은 발효 20일 후 7 log CFU/g으로 증가하였고, 25일 발효 후에 에탄올 농도가 1.3 %에 이르러 고춧가루 첨가 방법에 따른 에탄올 생성 농도에서 큰 차이를 보였다. 그러나 고춧가루 첨가시기에 따른 사과고추장의 전체적인 기호성에서는 큰 차이를 보이지 않았다.

• Steel and Composite Structures
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• 제46권5호
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• pp.689-707
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• 2023

Geopolymer concrete production is interesting as it is an alternative to portland cement concrete. However, workability, setting time and strength expectations limit the sustainable application of geopolymer concrete in practice. This study aims to improve the production of geopolymer concrete to mitigate these drawbacks. The improvement in the workability and setting time were achieved with the additional use of NaOH solution whereas an increase in the strength was gained with the addition of recycled steel fibers from waste tires. In addition, the use of 25% basalt powder instead of fly ash and the addition of recycled steel fibers from waste tires improved its environmental feature. The samples with steel fiber ratios ranging between 0.5% and 5% and basalt powder of 25%, 50% and 75% were tested under both compressive and flexure forces. The compressive and flexural capacities were significantly enhanced by utilizing recycled steel fibers from waste tires. However, decreases in these capacities were detected as the basalt powder ratio increased. In general, as the waste wire ratio increased, the compressive strength gradually increased. While the compressive strength of the reference sample was 26 MPa, when the wire ratio was 5%, the compressive strength increased up to 53 MPa. With the addition of 75% basalt powder, the compressive strength decreases by 60%, but when the 3% wire ratio is reached, the compressive strength is obtained as in the reference sample. In the sample group to which 25% basalt powder was added, the flexural strength increased by 97% when the waste wire addition rate was 5%. In addition, while the energy absorption capacity was 0.66 kN in the reference sample, it increased to 12.33 kN with the addition of 5% wire. The production phase revealed that basalt powder and waste steel wire had a significant impact on the workability and setting time. Furthermore, SEM analyses were performed.

• 동아시아식생활학회지
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• 제21권6호
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• pp.844-852
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• 2011

The purpose of this study was to determine the optimum chemical composition, color value, salinity, pH, total acidity, and texture for the production of short-term Green Gochujang using Cheongyang pepper powder and Meju powder. The results were as follows. The moisture content for Green Gochujang made from Cheongyang pepper powder was 33.50% for CON, and 27.21% for GG1. Crude fat and crude protein contents increased as the amount of added Meju powder increased (p<0.001). GG1 and CON contained 9.47% and 9.05% crude ash contents. Water activity was between 0.89 to 0.90. A higher amount of added Meju powder resulted in an increased color L value (p<0.001). CON showed the highest a value and b value compared to GG4, which had the lowest a and b values. Salinity was between 5.10% to 5.83%, which was lower compared to a former study. CON had a pH of 5.25, and GG4 had a pH of 6.06. Regarding total acidity, CON had a total acidity of 0.85, and GG4 had a total acidity of 0.44. Hardness value was highest in GG1 (1535.63), and lowest in CON (422.07) (p<0.001). GG1 showed the highest value in the adhesiveness property test, whereas CON showed the lowest value. GG1, which contained the highest amount of Cheongyang pepper powder showed the highest gumminess value (698.47). In an acceptance test, CON and GG3 showed the best appearance and scent value. GG3 received the highest interest in taste, texture, and overall quality. Through these results, GG3 made with 150 g of Chengyang Green pepper powder, 200 g of Meju powder, 600 g of starch syrup, 500 g of water, and 75 g of salt showed fine overall sensory interest, and therefore can be used for the production of fine Green Gochujang and Gochujang sauce.