• 한국식품과학회지
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• 제25권5호
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• pp.461-467
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• 1993

마이크로파 가열방법에 따른 감자친분의 특성을 검토하기 위하여 마이크로파를 직접 가열한 전분(A군)과 감자에 마이크로파를 가열하여 분리한 전분(B군)을 대상으로 이화학적 특성을 비교분석한 결과는 다음과 같다. 감자전분의 단백질과 회분 함량은 마이크로파 가열에 의하여 거의 변화되지 않았으나, 유리지질은 마이크로파 가열시간이 길수록 감소한 반면, 결합지질은 마이크로파 가열시간이 길수록 증가하였다. 인의 함량은 마이크로파 가열시간이 길수록 감소하였으며 전분에 마이크로파를 직접 가열한 A군 보다 감자에 마이크로파를 가열하여 분리한 전분인 B군의 변화 정도가 컸다. 광학 및 편광현미경으로 관찰한 전분입자의 형태와 복굴절현상은 마이크로파 가열방법, 가열시간에 따른 차이는 나타나지 않았으나, SEM으로 관찰한 입자의 표면형태는 A군의 경우 300초 가열시 약간의 변형이 나타났고, B군은 180초 때부터 표면의 변화가 나타났으나 변화정도는 A군보다 더 적었다. 물결합능력은 마이로파 가열시간이 길수록 A군, B군 모두 증가되었고, 아밀로오스 함량 및 Blue value는 마이크로파 가열 시간이 길수록 A군, B군 각각 감소하였다. 팽윤력과 용해도는 마이크로파 가열시간이 길어짐에 따라 각각 감소하였는데 마이크로파 가열방법에 따라 다소 차이가 있었다. 감자전분의 X-선 회절도는 A군의 경우 회절각도$(2{\theta})$ $5.4^{\circ}$에서의 peak 높이가 감소되었으나, B군은 회절선의 변화가 없었고 전체적인 결정성이 약간 증가하였다.

• 한국세라믹학회지
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• 제32권4호
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• pp.448-454
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• 1995

The effect of WO3 addition on microwave dielectric properties of BaTiO3-3{(1-x)TiO2-xWO3} system was studied. Addition of WO3 to this system resulted in the formation of BaWO4 and Ba2Ti9O20 phases. Both the dielectric constant (K) and the temperature coefficientof resonant frequency (Tf) were decreased with the amount of WO3 addition. The value of Q$\times$f0 was increased as the amount of WO3 was increased up to x=0.0275, and then decreased when x exceeded 0.03. At x=0.0275, this ceramic showed excellent microwave proprties of K=34-35, Q$\times$f0=50,000-53,000, and near zero ppm/$^{\circ}C$ of Tf.

• 한국세라믹학회지
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• 제29권3호
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• pp.177-182
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• 1992

The effect of heat-treatment temperature on the microwave absorbing properties was investigated in Ni0.8Zn0.2Fe2O4 specimens. The composite specimens were prepared by modling and curing the mixture of prereacted ferrite powder and silicone rubber. The measurement of complex permeability and permittivity was made by the reflection/transmission method. The most sensitive material constants with heat-treatment temperature is the imaginary (loss) component of permeability. The higher the heat-treatment temperature, the greater the magnetic loss. The composite specimens with high magnetic loss exhibited superior microwave absorbing properties. The quantitative estimation of microwave absorbing properties were made by plotting the observed material constants on the calculated solution map of impedance-matching.

• 대한전기학회논문지
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• 제43권3호
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• pp.442-446
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• 1994

In this study, microwave dielectric properties of 0.182BaO-0.818TiOS12T ceramics were investigated with sintering temperature and annealing time, and the application for the microwave dielectric resonator was studied. In the specimen simtered at 1400[$^{\circ}C$], dielectric constant, unloaded Q and temperature coefficient of resonant frequency had good values of 35.36, 5692, -4.43[ppm/$^{\circ}C$], respectively. The specimen which temperature coefficient of resonant frequency($\tau$f) was vared positive to negative value was selected, thereafter microwave dielctric properties was investigated with annealing time(0~4[hr]) in the fixed annealing temperature of 1350[$^{\circ}C$]. Increasing the annealing time, dielectric constant and unloaded Q were increased and temperature coefficient of resonant frequency was decreased.

• 한국세라믹학회지
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• 제41권1호
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• pp.9-12
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• 2004

The effect of x wt% CuO-y wt% $V_2O_5$ content on the microwave properties of $(Pb_{0.45}Ca_{0.55})[(Fe_{0.5}Nb_{0.5})_{0.9}Sn_{0.1}]O_3$ (PCFNS) ceramics was investigated. In order to decrease the sintering temperature and use as a Low Temperature co-firing Ceramics (LTCC), CuO-$V_2O_5$ are added in the PCFNS. The bulk density, dielectric constant (${\varepsilon}_r$) and quality factor(Q${\cdot}f_0$) increased with increase in CuO content within a limited value. The microwave properties were degraded with increases in $V_2O_5$ content. The temperature coefficient of the resonant frequency (${\tau}_f$) of PCFNS was shifted to positive value abruptly with increasing the $V_2O_5$ content, while the ${\tau}_f$ was slightly shifted to positive value with increasing the CuO content. The optimized microwave properties, ${\varepsilon}_r$ = 88, Q${\cdot}f_0$ = 6100 (GHz), and ${\tau}_f$ = 18 ppm/$^{\circ}C$, were obtained in $(Pb_{0.45}Ca_{0.55})[(Fe_{0.5}Nb_{0.5})_{0.9}Sn_{0.1}]O_3$ with 0.2wt% CuO 0.05 wt% $V_2O_5$ and sintered at $1000^{\circ}C$ for 3 h. The relationship between the microstructure and microwave dielectric properties of ceramics was studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM)

• 한국식품영양과학회지
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• 제27권3호
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• pp.489-494
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• 1998

For the purpose of improving the qualities of popcorn, potato, frozen hotdog and steamed egg, the effects of food height(0mm: HO, 5mm: H5, 10mm, 15mm: H15) for microwave cooking on physicochemical properties were investigated. In popcorn, weight loss was decreased as height increased while volume of popcorn was increased, which indicated that popcorn was poped very well as height increased. H10 showed the highest taste score in sensory evaluation. In potato, degree of gelatinization was increased as hight increased. H10 showed the highest overall acceptance score. In frozen hotdog, hardness of hotdog was decreased as hight increased and H15 showed the lowest hardness score (408.8g). In steamed egg, H5 showed the highest temperature and H10 showed the highest overall acceptance score. Physicochemical properties of food were changed by heating height of microwave heating.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
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• pp.86-90
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• 2001

Modified coaxial-slot antenna for minimally invasive microwave thermal therapy for liver tumor is studied in this paper. Minimally invasive microwave antenna in medicine are applied for hyperthermia for medical treatment for cancer, cardiac catheter ablation for ventricular arrhythmias treatments, microwave treatment of Benign prostatic hypertrophy, and so on. Microwave hyperthermal ablation for liver tumors is expected for enthusiasts as an alternative to curative surgical resection. Tumors have to heated up to 60 degree C to coagulate .cancer cells but less than 100 degree C to avoid evaporation. Temperature dependence of properties of the tissues should be considered for wide range of treatment. Electrical properties of liver tissue were measured for different temperatures. SAR distribution around the antenna into the liver are simulated using Remcom's XFDTD.

• 한국식품영양과학회지
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• 제27권1호
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• pp.109-114
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• 1998

For the purpose of improving quality of defrosted-frozen chicken leg, beef and yellow corvina, the effects of height(0mm : H0, 5mm : H5, 10mm : H10, 15mm ; H15) for microwave defrosting on their physicochemical properties were investigated. In frozen chicken leg, color values were not significant different between each treatment while H10 and H15 had the highest score on appearance. Hardness of defrosted chicken leg was increased as height increased. In frozen beef, temperature of beef after defrosting increased as hight increase and H10 had the highest appearance score. In frozen yellow corvina, H10 had the highest hardness and appearance scores. Physicochemical properties of color, texture and appearance of microwave-defrosted frozen food were changed by height within microwave oven.

• 한국전기전자재료학회논문지
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• 제16권4호
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• pp.311-316
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• 2003

Effects of pores on the microwave properties in microwave dielectric ceramics were studied by a computer simulation. Scattering matrix S$\_$21/ obtained from the network analyzer was compared to the S$\_$21/ obtained from the simulation. From electric field distribution, the dominant resonant TE$\_$01$\delta$/ mode could be easily determined. The effects of the porosity and pore size inside the dielectrics on the microwave properties were investigated by the HFSS simulation. When the total pore volume remains constantly, the quality factor decreased as the pore size Increases. As the total pore volume of the dielectrics increased. quality factor decreased.

• 한국세라믹학회지
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• 제33권9호
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• pp.1019-1023
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• 1996

The dielectric properties at microwave frequencies of B site complex perovskite La(Zn1/2Ti1/2)O3 which has +3 ion in A site were investigated. maximum Q*F value of the specimens was 59000 dielectric constant 34, temperature coefficient of resonant frequency -52 ppm/$^{\circ}C$. XRD pattern of the sintered specimen shows (111) ssuperlattice reflection which indicates Zn and Ti cation ordering.