• Journal of the Korea Furniture Society
• /
• v.12 no.2
• /
• pp.29-38
• /
• 2001

This study was carried out to develope a new process of flattening bamboo pieces(3 months old) by two steps of utilizing microwave oven and hot press. Internode bamboo pieces were impregnated with low molecular weight phenol formaldehyde resin (PF) under vacuum of 76 cmHg, heated in a household microwave oven in 1 minute, pressed on the temperature of $145^{\circ}C$ by the hot press for 10 minute, and then cooled by the cold press in their flattened form. The physical and mechanical . Properties of compressed flattened bamboo were as follows: 1) PF1(Mw:427) and PF2(Mw:246) sol. met the success of flattening of internode bamboo pieces in both of P. bambusoides and P. nigra var. PF2 showed the more plasticity to flatten the bamboo than PFI. The PF2 sol. with low molecular weight(Mw:246) gave the more weight gain than that of PF1 in the equal concentration. PF1 of 5% (NVC) and PF2 of 10% (NVC) sol. gave the best result for physical and mechanical properties and from a economical view point. 2) The PFI of 5% (NVC) sol. with low molecular weight decreased the water absorption of 62-63% and increased the bending strength (MaR) of 80-90%, compression strength of 43-54%. 3) The PF2 of 10% (NVC) sol. with low molecular weight decreased the water absorption of 56-57% and increased the bending strength (MaR) of 64-86%, compression strength of 39-63%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.205-208
• /
• 2001

Steady state and transient thermal analysis has been done by a finite element method in a diode of 12kV blocking voltage for microwave oven. The diode was fabricated by soldering ten pieces of 1200V diodes in series, capping a dummy wafer at the far end of diode series, and finally copper wire bonded for building anode and cathode terminal. In order to achieve high voltage and reliability, the edge of each diode was beveled and passivated by resin and epoxy with a thickness of 25$\mu\textrm{m}$ and 3,700$\mu\textrm{m}$, respectively. The chip size, thickness and material properties were very important factor for high voltage diode package. And also, thermal stress value was highest in the edge of diode and solder. So, design of edge in silicon was very important to thermal stress.

• Food Science and Preservation
• /
• v.17 no.3
• /
• pp.334-342
• /
• 2010

We evaluated the physicochemical and sensory properties of rice cake (Baekseolgi) admixed with various amounts of soybean peel and prepared using a microwave oven. Moisture content decreased gradually during storage but the decrease was less when soybean peel was present, compared with the control material p<0.05). Weight reduction was significantly inhibited as soybean peel level increased. The color lightness $(L^*)$ and redness $(a^*)$ values did not significantly change after addition of soybean peel. However, the yellowness $(b^*)$ value increased uponaddition of soybean peel p<0.05). The RVA properties decreased significantly with the addition of soybean peel, but pasting temperature increased. In terms of texture, neither springiness nor cohesiveness changed upon addition of soybean peel. The hardness, gumminess, and chewiness of Baekseolgi tended to decrease in proportion to the amount of soybean peel added. Adhesiveness rose gradually during storage but the increase was less when soybean peel was added, compared with control. On sensory testing, neither color nor flavor changed upon addition of soybean peel. Baekseolgi with 5% (w/w) soybean peel scored lowest in terms of taste. Hardness score and moisture level were highest when soybean peel was added to 2% or 3% (both w/w). Overall acceptability was greatest when soybean peel was added to 2% (w/w). Thus, Baekseolgi with 2% (w/w) added soybean peal was satisfactory. We conclude that addition of soybean peel to Baekseolgi prepared using a microwave oven improves physicochemical and sensory properties, and delays deterioration during storage.

• KSBB Journal
• /
• v.19 no.4
• /
• pp.269-273
• /
• 2004

A simple, fast and reproducible quantitative analysis method for sugar concentration composed in oligosaccharide mixture was developed. Two glass TLC plates were prepared per sample. After dipping one plate into the copper bicinchoninate reagent and the other plate into 5% sulfuric acid solution, both plates were baked in microwave oven until sugar spots were developed or the surface temperature of TLC plate becomes 60 to 70 $^{\circ}C$. The corrective factor values [F value =(the value of total sugar concentration converted as glucose unit/the value of reducing sugar concentration converted as glucose unit)/(polymerization degree of sugar)] of different molecular weight sugars were determined. Within the concentration of 0.25∼1.0 $\mu\textrm{g}$ in each sample loaded, the fructose-F (corrective factor value of fructose) was 0.45, yet for the higher concentration (2.5∼7.5 $\mu\textrm{g}$) fructose-F was 1.0. In case of glucose, in the range of 0.5∼7.5 $\mu\textrm{g}$, glucose-F was same as fructose-F, 1.0. However, as the molecular weight of sugar was increased, the F values were decreased in both maltodextrin and isomaltodextrin oligosaccharides in 0.5∼7.5 $\mu\textrm{g}$ of each sample loaded. Interestingly, F values were equal for the same molecular weight sugars, although the structures were different from each other. Using F value of each sugar, we could determine and compare the exact total sugar concentration of different molecular weight maltooligosaccharide and isomaltooligosaccharide. We also could determine if the unknown sugar was a reducing or non-reducing compound by using optimized TLC with microwave oven method.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.12
• /
• pp.29-42
• /
• 2018

Shale and mudstone in Daegu-Gyungbuk area have low strength and resistance to weathering compared to other rocks. Therefore, it is necessary to evaluate their strength depending on the degree of saturation and crack development. In this study, shales and mudstones were collected from several construction sites in Daegu-Gyungbuk area. Their basic material properties such as porosity, SEM, chemical component, and durability were tested. A porosity (absorptivity) of mudstone was 31% (25%), which was 6 (8) times higher than that of shale. Some mudstone was easily disintegrated with water and it consisted of highly-active clay mineral such as smectite type. These rocks were prepared by small cube specimens for unconfined compression test. An unconfined compressive strength of dry rock was compared with saturated one. Microwave oven was operated step by step to stimulate void water within a saturated rock, which resulted into high temperature and micro crack initiation within rocks. A strength of microwaved rocks was compared with operation time and crack initiation. As a result, the average unconfined compressive strength of dry and saturated shale was 62 and 33 MPa, respectively. The strength of mudstone for each condition was 11 and 4 MPa. When a rock became saturated, its strength decreased by 47% and 64% for shale and mudstone at average. In addition to saturation, a rock was in the microwave for 15 secs, its strength decreased into 49% for shale and 52% for mudstone. When a microwave oven operated up to 20 sec, a rock was crushed into several pieces and its temperature was approximately 200 degrees.

• Asian-Australasian Journal of Animal Sciences
• /
• v.23 no.10
• /
• pp.1380-1385
• /
• 2010

Buffalo meat patties with two fat levels, F1 (15% added fat) and F2 (5% added fat and 3% tapioca starch), were cooked in a pre-heated hot air oven (HO) at $175{\pm}2^{\circ}C$ for 15 min, in a microwave oven (MO) for 70 sec and by pressure cooking (PC) at 15 psi pressure for 10 min. and compared for physico-chemical, processing, sensory and microbiological quality attributes. F2 had significantly (p<0.05) higher value for the moisture and moisture protein ratio than F1. However, MO and PC patties had significantly (p<0.05) higher moisture content than HO-cooked buffalo meat patties irrespective of fat content. Highest fat percentage was in MO patties while the minimum was in PC patties. Moisture and fat retention and cooking yield were highest in MO patties irrespective of added fat content in the formulation. Cooking yield and dimensional parameters were better maintained in F2 than F1. Sensory scores viz. appearance and color, flavour, juiciness and texture for HO patties were better than other cooking methods. Sensory panelists rated overall acceptability of HO patties very good to excellent, whereas PC and MO patties were rated as good to very good irrespective of fat content. Microbiological quality was comparable in both groups irrespective of cooking methods used.

• The Journal of Korean Academy of Prosthodontics
• /
• v.34 no.4
• /
• pp.833-849
• /
• 1996

The material of choice for functional and esthetic reconstruction of maxillofacial defects is silicone. Silicone has appropriate physical properties for maxillofacial prosthesis but it has weak edge strength. Therefore, a proper combination of silicone and polyurethane sheet is recommended to improve this weakness. Various primers are also used to enhance the adhesive strength between silicone and polyurethane sheet. The purpose of this study was to determine the adhesive strength of silicone and polyurethane sheet. Silicone elastomer mixture was made by admixing MDX4-4210 elastomer (40%) and Silastic Medical Adhesive Type A(60%). This silicone elastomer mixture was attached to polyurethane sheet, using one of three different primers(1205, S-2260, or A-304), treated for 1, 2, 4, 6, and 8 hours. These were then polymerized in room temperature, dry-heat oven or microwave oven. Six specimens per each group, a total of 270 specimens were prepared for final test. The differences of T-peel bonding strengths were then determined by a test. The differences of T-peel bonding strengths were then determined by a test method that was recommended by American Society for Testing and Materials C794-80. The results were statistically analyzed using the ANOVA and Mutiple Range Tests(Tukey' HSD). The reults were as follow. 1. Type of primer, primer reaction time, and methods of polymerization showed significant correlation on the T-peel bonding strengths in adhesiveness between silicone and polyurethane sheet. 2. A-304 primer showed statistically higher in T-peel bonding strength than otehr type of primers except for the polymerization in microwave oven with reaction times of 2, 6 hours(p<0.05). 3. No significant differences in T-peel bonding strength were observed among the polymerization methods. 4. The effect of reaction time by the primer type and polymerization method showed statistically significant differences in bonding strength among different reaction times. And in most cases, reaction time of 1 or 2 hours showed higher T-peel bonding strength.

• Korean journal of food and cookery science
• /
• v.11 no.2
• /
• pp.98-103
• /
• 1995

The effect of blanching time, blanching water and power settings of microwave oven on the minerals retention in spinach and broccoli were investigated. The vegetables were blanched for 60, 120 and 180 sec, with water 0ml, 50ml and 100ml every 100 g of raw material at two different power settings (700w, 400w). The retention of minerals(Ca,K,Mg,Cu,Fe,Na,p) in spinach and broccoli were higher at the 400w power than 700w power level, regardless of blanching time. At the high power, the retention of minerals in spinach and broccoli were reduced remarkably as the blanching time increased. The reason for this is that the increasing power level results in greater water coming ou from the vegetable. Also, minerals in vegetable as coming out with this water loss in proportion to the blanching time.

• Korean journal of food and cookery science
• /
• v.10 no.4
• /
• pp.351-356
• /
• 1994

Comparisions were made for cooking times, internal temperatures, thiamin contents and textural properties of various portion weights of egg mixture cooked in a microwave oven at high and/or low power levels and in a conventional double boiler. The mean internal temperatures of conventionally cooked egg mixtures were 76.4~80.7$^{\circ}C$. When cooking was made by steaming, the mean internal temperature were comparable among samples. With the microwave cooking, the range of mean temperature was 83.8~96.4$^{\circ}C$, and they were significantly higher than the conventionally cooked egg mixtures. The hardness determination was conducted using universal testing machine and a taste panel. Samples cooked with steam or with larger portion weight had softer texture than samples cooked by microwaves or smaller amount, respectively. Mean internal temperature was significantly(r=0.99, p<0.05) correlated with mechanical hardness determination. Statistical analyses indicated no significant difference in the thiamin content among various treatments.

• Journal of the Korean Ceramic Society
• /
• v.40 no.8
• /
• pp.735-738
• /
• 2003

The PTFE composites for the microwave printed circuit board were prepared using woven glass fiber. The dielectric constant of the PTFE composites with oven glass fiber tended to decrease with an increase of immersion time, and was saturated at 3 times immersion. It resulted from the fact that fine powders of PTFE filled up at the pore and bend of woven glass fiber sufficiently. As the immersion time increased, the propagation velocity increased due to the reduction of dielectric constant.