• 한국식품조리과학회지
• /
• 제19권4호
• /
• pp.439-446
• /
• 2003

This study was performed to investigate the change in the chemical components of red pepper powder using different packaging materials and various storage conditions. Red pepper powders with 11 and 15% initial moisture content were packed with five different materials and stored at different temperatures (0, 20, and 30 C) for a one year period. Over the storage period, each combination was periodically sampled, and examined for composition changes. The five packaging materials were: linear low density polyethylene(LLDPE), nylon/LLDPE(Ny/LLDPE), saran coated ethylene vinyl acetate copolymer/linear low density polyethylene(B650), nylon/Tie/nylon/ethylene-vinyl alcohol copolymer/nylon/Tie/LLDPE(RDX-2787) and oriented polypropylene/alumimum/LLDPE(OPP/Al/LLDPE), and the three storage conditions were (28.3${\pm}$1.0)$^{\circ}C$ with (15.5${\pm}$2.8)% relative humidity, (18.6${\pm}$0.5)$^{\circ}C$ with (46.6${\pm}$4.9)% RH, and (0${\pm}$2)$^{\circ}C$ with (80${\pm}$10)% RH, respectively. The moisture contents of all samples changed according to the relative storage humidity, except those of the samples packed with OPP/Al/LLDPE, which remained constant throughout the storage period. The capsaicinoids content of the red pepper powder did not change significantly for 6 months, but gradually decreased after that until about 85% of the original amount remained at the final stage of storage. The ASTA color values of all samples decreased gradually throughout the storage period. The higher the storage temperature, the more severe the deterioration. The color deterioration seemed greatly related to the existence of oxygen, as the deterioration was especially severe in the samples packed with LLDPE and B650, where the oxygen transmission rate were highest among the five packaging materials.

• Advances in concrete construction
• /
• 제15권3호
• /
• pp.191-202
• /
• 2023

Palm oil fuel ash (POFA) is a newly emerging pozzolanic material having high amount of silica content. Various forms of POFA were used in cement-based materials (CBMs) in replacement of cement in different dosages of low and high volume. Although, there are many researches on POFA to be used in concrete and mortar, however, this material was not practically used in the construction industry. Engineers and designers need to be confident to use any new developed materials by knowing all engineering properties at short and long terms. As durability concern, concrete pH value is one of the most important properties. Portland cement produces are alkaline initially, however, it may be reduced due to aging and its components. It is believed that by incorporation of supplementary cementitious materials in CBMs the pH value reduces due to utilization of Ca(OH)₂ in pozzolanic reaction. This study is the first attempts to understand the pH value of mortars containing up to 30% POFA under different curing conditions and its changes with time. The results were also compared with the pH of ground granulated ballast furnace slag (GGBFS) and fly ash (FA) content mortars. In addition, the compressive strength of different mortars under different curing conditions were also studied. The results showed that the pH value of control mix (without cementitious materials) was more than all the blended cement mortars indifferent curing conditions at the same ages. However, there was a reducing trend in the pH value of all mortar mixes containing POFA.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
• /
• pp.24-32
• /
• 2004

The characteristics of heat transfer from horizontal cylinder immersed in both a riser and downcomer of a circulating fluidized beds were investigated experimentally under different values of solids mass flux, superficial air velocity, particle size diameter, and different bed materials. The test results indicated that local heat transfer coefficients in both riser and downcomer are strongly influenced by angular position, and mass flux, as well as by particle size and bed materials. The local heat transfer coefficients around a circumference of the cylinder inside a riser and downcomer of a CFB exhibited a general tendency to increase with decreasing particle size and increasing solids mass flux and vary with different bed materials. Also the averaged heat transfer coefficient calculated from local heat transfer coefficient exhibited the same trend as a local i.e increase with decrease particle size and increasing solids mass flux and vary with varying bed materials. The general trend for a riser local heat transfer coefficient is decrease with increase angle until ${\Phi}$ = 0.5-0.6 (Where at angle =180$^{\circ}$ ${\Phi}$ =1). Also the general trend for a local heat transfer coefficient in downcomer is to increase with increase the angle until ${\Phi}$= ${\theta}/{\Pi}$ = 0.3-0.5 (Where at angle =180$^{\circ}$ ${\Phi}$ =1). Comparison the results of the heat transfer in the riser and downcomer of a circulating fluidized beds shows that they have approximately the same trend but the values of heat transfer coefficients in riser is higher than in downcomer.

• 한국세라믹학회지
• /
• 제56권4호
• /
• pp.394-398
• /
• 2019

In this paper, the joining characteristics of GDC-LSM ceramics with Crofer 22 APU metal alloys was investigated at different brazing temperatures and holding times by reactive air brazing. Brazing was performed using Ag-10 wt% CuO filler, at three different temperatures (1000, 1050, and 1100℃ for 30 minutes) as well as for three different holding times (10, 30, and 60 minutes at 1050℃). The interfacial microstructures were examined by scanning electron microscopy and the joining strengths were assessed by measuring shear strengths at room temperature. The results show that with increasing brazing temperature and holding time, joint microstructure changed obviously and shear strength was decreased. Shear strength varied from a maximum of 100±6 MPa to a minimum of 18±5 MPa, depending on the brazing conditions. These changes were attributed to an increase in the thickness of the oxide layer at the filler/metal alloy interface.

• 대한치과보철학회지
• /
• 제27권2호
• /
• pp.249-259
• /
• 1989

Dental impression materials often become contaminated with patients' saliva and blood which creates the potential for cross-infection. It was the purpose of this study to investigate the effects of disinfection of three different rubber impression materials with four different disinfecting solutions. Polysulfide, vinyl polysiloxane and polyether impression materials were mixed according to the manufacturer's directions and samples were formed on a stainless steel model. On removal from the standard model, impressions were immersed in a disinfectant (acid-potentiated glutaraldehyde, phenollic compound, chlorine compound, iodophor) at room tempera tures for ten minutes. After disinfection, the distance between reference points(linear dimension) was measured using the non-contact automatic cordinate measuring projector(MZ-1, Nikon). Through statistical analyses on the data from this study,. the following conclusions were obtained. 1. Polysulfide, vinyl polysiloxane impressions were disinfected without dimensional change.(p>0.05) 2. Polyether impressions which were immersed in acid-potentiated glutaraldehyde were statistically different from control group.(p<0.05) But the amount of shrinkage(0.04%) would not be clinically significant. 3. By immersion of polysulfide, vinyl polysiloxane, polyether impressions in Banicide, Biocide, Multicide plus, sodium hypochlorite for ten minutes, clinically accurate impressions were obtained without dimensional change.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.622-624
• /
• 2008

This investigation studies the effects of material properties and corresponding propagation wave types on optimal configurations of sound absorbing porous materials in maximizing the absorption performance by topology optimization. The acoustic behavior of porous materials is characterized by their material properties which determine motions of the frame and the air. When the frame has a motion, two types of compressional wave propagate in the porous material. Because each wave in the material make different influence on the absorption performance, it is important to understand the relative contribution of each wave to the sound absorption. The relative contribution of the propagating waves in a porous material is determined by the material properties, therefore, an optimal configuration of a porous material to maximize the absorption performance is apparently affected by the material properties. In fact, virtually different optimal configurations were obtained for absorption coefficient maximization when the topology optimization method developed by the authors was applied to porous materials having different material properties. In this investigation, some preliminary results to explain the findings are presented. Although several factors should be considered, the present investigation is focused on the effects of the material properties and corresponding propagation waves on the optimized configurations.

• 한국가구학회지
• /
• 제25권3호
• /
• pp.223-232
• /
• 2014

To make metalized wood composites of 10 different korean wood species, it was tested by Low temperature melting Bi-Sn alloy injection method at high temperature and high pressure condition. Metalized wood composite of each wood species had light ash color, but still maintained its own natural wood grain and wood figures. It was evaluated on coating properties. Furthermore, it also was check on effect of coating as like a changes of main color, wood grain and wood figures. The results of test were following as; a coating properties as like a cold resistance, heat resistance, acid resistance, alkali resistance, durability of abrasion, and cross-cut test was proper on the conditions of the KS standard. And, In aspect of color changes, the metalized wood composites of 10 different korean wood species had a light ash color, but still maintained its own natural wood grain and wood figures. Also, the more weight per gain of alloy is, the more grey background of metalized wood composite is.

• 한국재료학회지
• /
• 제23권3호
• /
• pp.177-182
• /
• 2013

Nanosphere lithography is an inexpensive, simple, high-throughput nanofabrication process. NSL can be done in different ways, such as drop coating, spin coating or by means of tilted evaporation. Nitride-based light-emitting diodes (LEDs) are applied in different places, such as liquid crystal displays and traffic signals. The characteristics of gallium nitride (GaN)-based LEDs can be enhanced by fabricating nanopatterns on the top surface of the LEDs. In this work, we created differently sized (420, 320 and 140 nm) nanopatterns on the upper surfaces of GaN-based LEDs using a modified nanosphere lithography technique. This technique is quite different from conventional NSL. The characterization of the patterned GaN-based LEDs revealed a dependence on the size of the holes in the pattern created on the LED surface. The depths of the patterns were 80 nm as confirmed by AFM. Both the photoluminescence and electroluminescence intensities of the patterned LEDs were found to increase with an increase in the size of holes in the pattern. The light output power of the 420-nm hole-patterned LED was 1.16 times higher than that of a conventional LED. Moreover, the current-voltage characteristics were improved with the fabrication of differently sized patterns over the LED surface using the proposed nanosphere lithography method.

• 반도체디스플레이기술학회지
• /
• 제13권1호
• /
• pp.43-49
• /
• 2014

Zinc-tin oxides (ZTO) thin film transistors have been fabricated at different process pressure via re sputtering technique. TFT properties were improved by depositing channel layers at lower pressure. From the analysis of TFTs comprised of multi layer channel, deposited consecutively at different sputtering pressure, it was suggested that the electrical characteristics of TFTs were mainly affected by interfacial layer due to their high conductance, however, the stability under the NBIS condition was influenced by whole bulk layer due to low concentration of positive charges, which might be generated by the oxygen vacancy transition, from Vo0 to $Vo^{2+}$. Those improvements were attributed to increasing sputtered target atoms and decreasing harmful effects of oxygen molecules by adopting low sputtering pressure condition.

• 한국재료학회지
• /
• 제19권12호
• /
• pp.674-679
• /
• 2009

Yttria stabilized zirconia single crystals show plastic deformation at high temperatures by activating dislocations. The plastic deformation is highly dependent on crystallographic orientation. When the samples were deformed at different orientations, stress-strain curves changed by operating different slip systems. The strength of samples was also highly dependent on crystallographic orientation, i.e., samples without yield drop showed higher strength than that of samples exhibiting yield drop. The slip systems in the sample deformed along <112>, <111> and <001> agreed with the theoretical values of the plastic deformation, following Schmid's Law. Dislocations play a major role in the plastic deformation of this crystal. At the early stages of plastic deformation, all samples exhibited dislocation dipoles and, in the later stages, dislocation interactions occurred by forming nodes, tangles and networks. In this study, three different orientations, [11-2], [111] and [001] were employed to explain the plastic deformation behavior. A microstructural analysis was performed to elucidate the mechanism of the plastic behavior of this crystal.