• 한국지반공학회논문집
• /
• 제26권4호
• /
• pp.15-26
• /
• 2010

폐타이어 파우더 혼합에 따른 동상억제 메커니즘을 규명하기 위해, 부동수, 열전도율, 동상실험 등 3종류의 실내실험을 수행하였다. 본 연구에서는 폐타이어 혼합에 따른 투수계수 변화에 주목하여 먼저 마동결토의 불포화 투수계수를 계산하였고 ice-impeding factor, 혼합토내 토립자와 폐타이어 단면적을 고려하여 동결토frozen fringe내의 온도변화에 따른 투수계수 특성을 분석하였다. 그 결과 흡수속도와 투수계수 사이에는 비례관계가 존재함을 확인하였고, 동상성 저하의 주된 원인은 폐타이어 파우더 혼합에 따른 부동수분량과 투수계수의 감소임을 알 수 있었다. 또한 폐타이어 파우더 혼합토 구성성분의 체적비를 이용하여 흙과 폐타이어 간극내의 수분량을 정량적으로 산출하였다.

• 한국진공학회지
• /
• 제6권S1호
• /
• pp.160-165
• /
• 1997

Yttria stabilized zirconia coating is an attractive material for several engineering applications. In order to produce coatings with consistent and reliable performance it is important to understand the influence of spraying parameters on the coating properties and optimize the spraying parameters. In this paper the low pressure plasma spray(LPPS) deposition of as-received zirconia powder has been investigated using simple one-factor-at-a-time approach. The deposition efficiency was chosen to evaluate the melting characteristics of the as-received zirconia powder. The results obtained indicated that the deposition efficiency of zirconia powder is very sensitive to the spraying parameters such as plasma gas flow rate and ranges from 24% to 57% The microstructure and the phase composition of zirconia coating deposited with the different plasma spraying parameters were also examined by SEM and XRD respectively. The relationship between deposition efficiency and the microstructure of zirconia coating was discussed.

• 한국식생활문화학회지
• /
• 제25권4호
• /
• pp.473-479
• /
• 2010

The purpose of this study was to investigate the quality characteristics of Maejakgwas prepared with various concentrations of Enteromorpha intenstinalis powder (0, 1, 2, 3, 4%) substituted for flour. The pH of the Maejakgwas dough decreased significantly in response to all levels of Enteromorpha intenstinalis powder (EIP). However, there were no significant differences in dough values among the test groups. Furthermore, when the spread factor values were compared among the groups, they were found to be inversely proportional to the EIP concentration. In addition, the Hunter's color L, a and b values decreased significantly as the level of EIP increased. Moreover, the addition of 2~4% EIP resulted in increased hardness, cohesiveness, springiness and brittleness compared to those of control. Finally, the results of an acceptance test showed that Maejakgwas containing 3% EIP had the highest scores.

• 한국분말재료학회지
• /
• 제17권5호
• /
• pp.385-389
• /
• 2010

Titanium powders have been usually produced by de-hydrogenating treatment in vacuum with titanium hydride ($TiH_2$) powders prepared by milling of hydrogenated sponge titanium, $TiH_x$. The higher stoichiometry of x in $TiH_x$, whose maximum value is 2, is achieved, crushing behavior is easier. $TiH_x$ powder can be, therefore, easy to manufactured leading to obtain higher recovery factor of it. In addition, contamination of the powder can also minimized by the decrease of milling time. In this study, the hydrogenation behavior of sponge titanium was studied to find the maximum stoichiometry. The maximum stoichiometry in hydride formation of sponge titanium could be obtained at $750^{\circ}C$ for 2 hrs leading to the formation of $TiH_{{\sim}1.99}$ and the treating temperatures lower or higher than $750^{\circ}C$ caused the poor stoichiometries by the low hydrogen diffusivity and un-stability of $TiH_x$, respectively. Such experimental behavior was compared with thermodynamically calculated one. The hydrogenated $TiH_{1.99}$ sponge was fully ball-milled under -325 Mesh and the purity of pure titanium powders obtained by de-hydrogenation was about 99.6%.

• 한국식생활문화학회지
• /
• 제27권2호
• /
• pp.225-232
• /
• 2012

This study was conducted to investigate the effects of acorn ($Quercus$ autissima carruther) powder on the antioxidant activity and quality characteristics of cookies. Cookies were prepared with different amounts of acorn powder (at ratios of 0, 0.5, 1, 3 and 5% to total flour quantity). Antioxidant activity was estimated based on DPPH free radical scavenging activity and total phenol content in acorn powder and cookies. To analyze quality characteristics, bulk density, pH of the dough, spread factor, loss rate, leavening rate, color, texture profile analysis, and sensory evaluations were measured. Loss rate, a values, total polyphenol contents and DPPH free radical scavenging activity of cookies significantly increased with increasing acorn powder content (p<0.01), whereas pH of the dough, L values and b values of the cookies significantly decreased with increasing acorn powder content (p<0.01). The results of sensory evaluation (appearance, taste, flavor, texture and overall preference) demonstrate that the 3% acorn cookie group showed the highest degree of preference among all items of added acorn powder. From these results, we suggest that acorn is a good ingredient for increasing the consumer acceptability and functionality of cookies.

• 한국식품조리과학회지
• /
• 제22권5호통권95호
• /
• pp.712-719
• /
• 2006

Sugar cookies using various levels of citron powder were prepared and the physicochemical and sensory characteristics were investigated in this study. The pH of the dough was relatively lower in the groups with increased citron powder. The yellowness of dough color was significantly increased from value of 23.47 to 36.99 as the substitution levels of citron powder content was increased (p<0.05). The degree of gelatinization of the dough measured using DSC was reduced with increasing delayed with the increased amount of the powder content. Cookies with powders content of 4-6 g showed significantly lower water contents than compared to those with 0-2 g(p<0.05). The spread factor tended to decrease as the substitution levels of the sample groups were increased. The results of sensory characteristics showed significantly higher bitterness and lower sweetness with the 6 g substituted sample group at (p<0.05). Desired citron cookie was prepared with the group of a substitution levels of 4 g citron powder from the confounded viewpoint of the physicochemical and sensory properties that were investigated.

• 소성∙가공
• /
• 제32권3호
• /
• pp.114-121
• /
• 2023

During rolling, rolling mill rolls endure wear when shaping metal billets into a desired form, such as bars, plates, and shapes. Such wear affects the lifespan of the rolls and product quality. Therefore, in addition to rigidity, wear performance is a key factor influencing the performance of rolling mill rolls. Conventional methods such as casting and forging have been used to manufacture rolling mill rolls. However, powder alloying methods are increasingly being adopted to enhance wear resistance. These powder manufacturing methods include atomization, canning to shape the powder, hot isostatic pressing to combine the powder alloy with conventional metals, and various wear performance tests on rolls prepared with powder alloys. In this study, numerical simulations and experimental tests were used to develop and elucidate the wear analysis mechanism of rolling mill rolls. The wear characteristics of the rolls under various rolling conditions were analyzed. In addition, experimental tests (wear and surface analysis tests) and wear theory (Archard wear model) were used to evaluate wear. These tests were performed on two different materials in various powder states to evaluate the different aspects of wear resistance. In particular, this study identifies the factors influencing the wear behavior of rolling mill rolls and proposes an analytical approach based on the actual production of products. The developed wear analysis mechanism can serve the future development of rolls with high wear resistance using new materials. Moreover, it can be applied in the mechanical and wear performance testing of new products.

• 한국수산과학회지
• /
• 제42권4호
• /
• pp.395-398
• /
• 2009

This study was conducted to investigate the effects of supplemental medicinal herb mixture, laver powder and paprika powder in extruded pellet (EP) on growth and feed utilization of juvenile olive flounder. Triplicate groups of fish (average body weight of 19.6 g) were fed four experimental EPs containing 0.2% medicinal herb mixture (MHM), 1% laver powder (LP), 1% paprika powder (PP) and without supplementation (CON) for 9 weeks. Weight gain, daily feed intake, hepatosomatic index and condition factor were not influenced by dietary additives. Peed efficiency and protein efficiency ratio of flounder fed the diet containing laver powder were significantly higher than those of fish fed the medicinal herb mixture and paprika powder (P<0.05), but not significantly different from control group. The results of this study suggest that all tested additives in the dietary formulation did not affect growth and feed utilization of olive flounder.

• 농업과학연구
• /
• 제49권4호
• /
• pp.905-917
• /
• 2022

It is well known that the fruit of the vitamin tree (Hippophae rhamnoides L.) provides excellent anti-diabetic, antibacterial, immune regulation, anti-inflammatory, and anti-aging effects. In some countries including Europe the fruit has been added to certain foods to develop functional foods. The present research was carried out to elucidate the biological function of vitamin tree fruit powder added to fermented milk. It was found that there was an antioxidant effect of yoghurt made with vitamin tree fruit powder, and this effect was greater with increased incubation time and amount of vitamin powder, as shown by 1,1-diphenyl2-picrylhydrazyl (DPPH) and 2,2-anziobis (3-ehtylbenzothiazoline-6-sulfonic aicd) (ABTS) radical scavenging activities. The antibacterial effect of yoghurt containing vitamin tree fruit powder was shown to be effective against four pathogenic microorganisms, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonela Typhimurium. In particular, yoghurt supplemented with 5% of vitamin tree fruit powder showed the best antibacterial effect. The yogurt containing the vitamin tree fruit powder significantly inhibited the expression of the anti-inflammatory cytokines interleukin (IL)-6 (yogurt [Y] + Hippophae rhamnoides L. powder [HP] and yogurt containing 5% Hippophae rhamnoides L. powder [HPY]) and IL-1β (HP, Y + HP and HPY) in a concentration-dependent manner among tumor necrosis factor (TNF)-α, IL-6, IL-1, and induced nitric oxide synthase (iNOS). Our results clearly demonstrated that vitamin tree fruit powder could be a good functional ingredient for improving health through yoghurt manufactured with vitamin tree.

• 한국세라믹학회지
• /
• 제30권2호
• /
• pp.131-138
• /
• 1993

The effects of silane coupling agents on the injection molding process were investigated using silicone nitride mixtrues with a binder system containing polypropylene as a major binder (55vol% solid loading). The formation of bonding between silicon nitride powder and coupling agents was confirmed through the analyses of powder surface. The use of coupling agents improved mixing characteristics judged by the torque change during mixing process. the coupling agents also reduced molten viscosity of the mixture considerably, which is a main factor to determine the flow of the mixture. However, the bonding between coupling agents and polymers had a negative effect on the debinding process by retarding the thermal decomposition.