• Journal of the Korean Ceramic Society
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• v.48 no.1
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• pp.14-19
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• 2011

Microwave heating (MW) was studied for the sintering of amorphous powders. In comparison to conventional heating (CV), the results show that microwave heating has the potential to substantially accelerate the sintering process and allow for highly densified solidification by eliminating the pores and increasing the shrinkage rate. In the heat treatment to synthesize aluminum borate ($Al_{18}B_4O_{33}$) whiskers from precursors, it was found that microwave heating helps the formation of $Al_{18}B_4O_{33}$ crystal as well as the decrease of crystallization temperature of $Al_{18}B_4O_{33}$ to a level significantly lower than the previously reported value of $1050^{\circ}C$.

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.122-127
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• 2018

PURPOSE. This study evaluated the dimensional stability of a complete-arch prosthesis processed by conventional method in water bath or microwave energy and polymerized by two different curing cycles. MATERIALS AND METHODS. Forty maxillary complete-arch prostheses were randomly divided into four groups (n = 10): MW1 - acrylic resin cured by one microwave cycle; MW2 - acrylic resin cured by two microwave cycles: WB1 - conventional acrylic resin polymerized using one curing cycle in a water bath; WB2 - conventional acrylic resin polymerized using two curing cycles in a water bath. For evaluation of dimensional stability, occlusal vertical dimension (OVD) and area of contact points were measured in two different measurement times: before and after the polymerization method. A digital caliper was used for OVD measurement. Occlusal contact registration strips were used between maxillary and mandibular dentures to measure the contact points. The images were measured using the software IpWin32, and the differences before and after the polymerization methods were calculated. The data were statistically analyzed using the one-way ANOVA and Tukey test (${\alpha}=.05$). RESULTS. The results demonstrated significant statistical differences for OVD between different measurement times for all groups. MW1 presented the highest OVD values, while WB2 had the lowest OVD values (P<.05). No statistical differences were found for area of contact points among the groups (P=.7150). CONCLUSION. The conventional acrylic resin polymerized using two curing cycles in a water bath led to less difference in OVD of complete-arch prosthesis.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1957-1964
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• 2011

Various reaction conditions uding temperature, time and type and concentration of templates have been changed in order to facilely synthesize, especially with microwave (MW) heating, SAPO-34 molecular sieves. SAPO-34 molecular sieve can be synthesized rapidly with microwave irradiation from a gel containing tetraethylammonium hydroxide (TEAOH) as a template. However, other several templating molecules lead to SAPO-5 molecular sieve under microwave irradiation even though SAPO-34 is obtained by conventional electric synthesis from the same reactant gels. Moreover, SAPO-34 can be obtained more easily by increasing the TEAOH or silica concentration or by increasing the reaction temperature. SAPO-34 can be obtained within 5 min in a selected condition (high temperature of 210 $^{\circ}C$) with microwave heating, which may lead to a continuous production of the important material. SAPO-34 synthesized by microwave irradiation is homogeneous and small in size and shows acidity and a stable performance in the dehydration of methanol and 2-butanol to olefins, suggesting potential applications in acid catalysis.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.126-127
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• 2007

본 연구는 Microwave를 이용하여 활성탄의 재생특성을 파악하는데 목적을 두었다. Microwave의 조사횟수를 달리하였을때 활성탄의 특성 변화분석하였다. BET 분석결과 조사 후 분석 값이 조사 후 분석 값보다 떨어짐을 알 수 있다. 이는 MW를 조사함으로써 활성탄의 온도가 상승이 되고 이로 인해 기공의 파괴가 있음을 알 수 있다. 각 물질별로 20번씩 조사 하여서 나타난 결과를 보면 비표면적이 각각 8.2%(A), 5.68%(B), 0.38%(C) 줄었다. 활성탄 C의 경우는 조사 후 감소된 면적이 가장 적었는데 이는 먼저 제조하였던 활성탄의 경우는 활성탄의 성분이 제기능이 못할 정도로 소성을 하였거나 탄소성분의 변질이 있었음을 알 수 있다.

• Korean journal of food and cookery science
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• v.15 no.3
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• pp.264-271
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• 1999

This study was conducted to know the storage stability of Yackwa, a traditional Korean fried cookie, prepared by two different cooking methods; deep fat frying at 160$^{\circ}C$ for 8 min (DFF), and preheating Yackwa dough and then deep fat frying at 180$^{\circ}C$ for 2 min (MW/DFF). Soybean oil (SBO), hydrogenated soybean oil (HSBO) or hydrogenated palm oil (HPO) were used for frying Yackwa. Compared to Yackwa prepared by DFF, all MW/DFF Yackwa samples had low fat content and high moisture content. MW/DFF saved frying time 6 min compared with DFF. Non-hydrogenated soybean oil for frying fats was replaced with hydrogenated types of soybean oil and palm oil to improve the storage stability of Yackwa. To investigate the oxidation stability of Yackwa during the accelerated storage for 15 days at 60$^{\circ}C$, acid value, anisidine value, peroxide value and oxidation value of Yackwas were measured. Acid values of Yackwa made by MW/DFF were higher than those made by DFF through the whole storage periods, regardless of frying fats. Peroxide and anisidine values of Yackwa coated with syrup were much lower than those without syrup. MW/DFF cooking method, using hydrogenated soybean oil or hydrogenated palm oil for frying, showed lowering effects on peroxide value as well as anisidine value, resulting in improved oxidation stability of Yackwa during the storage. In sensory evaluation, the acceptability of MW/DFF Yackwa was higher than those of the commerical products. Yackwa prepared by MW/DFF cooking method using hydrogenated palm oil, showed the highest acceptability in color, taste and texture among the samples.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.928-930
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• 1992

The design beam energy of PLS(Pohang Accelerator Laboratory) Linac is 2Gev. The linac employs total 11 units of modulators and klystrons. The maximum peak output powers of the modulators are 200MW (400kV, 500A, 4.4$\mu$S flat-top, 800$\Omega$ load) to drive the klystrons which have the peak microwave power of 80MW. Prior to the development of the 200MW modulators, a prototype 150MW modulator has been constructed and tested. We have achieved output pulses of 350kV, 420A and 3.5$\mu$S flat-top with 840$\Omega$ water load. In this article, the test results and computer simulations of charging, De-Q'ing, and discharging are presented.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.242-245
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• 2008

A four-channel selective microwave filter was demonstrated incorporating an optical resonator router, which is constructed by integrating a $1{\times}4$ space switch with an arrayed ring filters featuring different free spectral ranges. The center frequency of each channel was determined by the FSR of the corresponding ring resonator, and the four channels centered at 10 GHz, 16 GHz, 18 GHz and 20 GHz were individually selected to provide a bandpass filtering via the control voltage applied to the switched resonator.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.181-198
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• 1998

In order to determine the optimum pasteurization conditions by microwave heating(MWH) at $50^{\circ}C{\sim}70^{\circ}C$ for 30 minute compared with water bath heating(WBH) at $65^{\circ}C$ for 30minute during storage at $5^{\circ}C$, the chemical composition, microbiological changes and keeping quality were examined and the results were as follows: 1. The fat protein lactose, total solid contents of raw milk, at $50{\sim}70^{\circ}C$ for 30 min. in MWH and at 65 for $30^{\circ}C$ min. in WBH did not changed significantly during the storage at $5^{\circ}C$. 2. The pH and acidity for the raw milk untreated were 6.75 and 0.16%, and those of MWH heated and WBH milk wee 6.75~6.50 and 0.16%~0.19%, phosphatase test were negative at $61^{\circ}C$ for 20 min. at $62^{\circ}C$ for 15 min. at $63^{\circ}C$ for 10 min. at $64^{\circ}C$ for 5 min. at $65^{\circ}C$ for 5 min. in MWH and at $65^{\circ}C$ for 30 min. in WBH. 3. Whey protein content was $18.53mg/m{\ell}$ in raw milk untreated, however, those were decreased as the heating temperature increased. The proteolytic activity of treated milk by WBH(44%) was lower than that by MWH(94%). 4. Total bacteria counts were $2.8{\times}10^5CFU/m{\ell}$ in raw milk untreated, $2.8{\times}10^3CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. $2.4{\times}10^3CFU/m{\ell}$ at $70^{\circ}C$ for 30 min. in MWH and $3.0{\times}10^3CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. in WBH. Because total bacteria count did not increased in MWH at $65^{\circ}C$, $70^{\circ}C$ for 30 min. and $65^{\circ}C$ for 30 min. in WBH during the 10 days storaging, Also, total bacteria counts for treated milk were a most drastic decrease after $61^{\circ}C$, $62^{\circ}C$, $63^{\circ}C$, $64^{\circ}C$, $65^{\circ}C$ for 5 min. in MWH. 5. Coliform bacteria counts were $2.6{\times}10^3CFU/m{\ell}$ in raw milk untreated. There were not detected at $55^{\circ}C{\sim}70^{\circ}C$ for 30 min. in MWH and at $65^{\circ}C$ for 30 min. in WBH. Coliform bacteria counts were not detected after $61^{\circ}C$, $62^{\circ}C$, $63^{\circ}C$, $64^{\circ}C$, $65^{\circ}C$ for 5 min. in MWH. 6. Thermoduric bacteria counts were $5.2{\times}10^4CFU/m{\ell}$ in raw milk untreated, $2.0{\times}10^3CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. $1.9{\times}10^3CFU/m{\ell}$ at $70^{\circ}C$ for 30min. in MWH and $2.2{\times}10^3CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. in WBH. Because thermoduric bacteria counts did not increased in MWH at $65^{\circ}C$, $70^{\circ}C$ for 30 min. and $65^{\circ}C$ for 30 min. in WBH during the 10days storaging. Also, thermoduric bacteria counts were a most drastic decrease after $61^{\circ}C$, $62^{\circ}C$, $63^{\circ}C$, $64^{\circ}C$, $65^{\circ}C$ for 5 min. in MWH. 7. Psychrotrophic bacteria counts were $2.8{\times}10^5CFU/m{\ell}$ in raw milk untreated, $2.0{\times}10^1CFU/m{\ell}$ at $65^{\circ}C$ for 30 min. $2.0{\times}10^1CFU/m{\ell}$ at $70^{\circ}C$ for 30 min. in MWH and $3.0{\times}10^1CFU/m{\ell}$ at $65^{\circ}C$for 30 min. in WBH. Because psychrotrophic bacteria counts did not increased in MWH at $65^{\circ}C$, $70^{\circ}C$ for 30min. and $65^{\circ}C$ for 30 min. in WBH during the 10 days storaging. Also, psychrotrophic bacteria counts were a most drastic decrease after $61^{\circ}C$, $62^{\circ}C$, $63^{\circ}C$, $64^{\circ}C$, $65^{\circ}C$ for 5 min. in MWH.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.631-637
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• 1999

An investigation was carried out to study the effects of aging time, storage temperature, and drying type on the physical, chemical and sensory properties of Korean rice cake. Water content and cooking properties were significantly influenced by aging time and storage temperature. However, aging time did not affect the soup turbidity. Difference in water content was noticeable by drying type. The microwave treated rice cake (MW) showed a higher water content than the other ones. The lightness (L-value) was not affected by the aging time and drying type. Rice cake storaged at 4oC showed the highest L-value. The textural properties of rice cake were influenced by the all sources of variables. There was a significant difference in hardness between microwave and hot air treated rice cake (MWH), and microwave and vacuum treated rice cake (MWV). In the sensory properties, mean intensities of all attributes except chewiness were significantly different among drying types. The MWV showed a higher acceptability than the MW and the MWH. Scanning electron photomicrographs revealed that the MWV has more porous structure. The MWV was the most desirable one as determined by the physical, chemical and sensory evaluation.

• Applied Biological Chemistry
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• v.37 no.2
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• pp.77-84
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• 1994

Sweetpotatoes were baked (BK), microwaved (MW), microwaved/baked (MWBK), and microwaved/hold/microwaved (MWHO). Sugars, Huntercolors, compression and shear forces, sensory scores, moisture content, starch, and alcohol insoluble solids (AIS) were determined for each treatment. The BK roots contained higher (p<0.05) amount of sugars and less (p<0.05) starch. The MW roots contained higher (p<0.05) amount of starch, AIS, and less (p<0.05) sugar. The BK product resulted in the least (p<0.05) compression and shear forces needed to break it. The MW product demanded the greatest (p<0.05) force. The MWHO showed very similar results to the BK. Sensory scores for the BK and the MWHO sweetpotatoes were very acceptable. In color scores, the MWHO products were very acceptable and similar to the BK in flavor.