• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.45-54
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• 2004

Microwave characteristics of ridge type CPW traveling-wave(TW) electroabsorption modulator and photodetector are affected by the thickness of intrinsic layer, width of guiding layer, and the separation of signal and ground electrodes. These factors are determined effective index of microwave and characteristic impedance due to changing of capacitance(C) and inductance(L) of device. However, conventional equivalent circuit of TW-structure is approximated to microstrip and CPW transmission line by distribution of electric and magnetic fields, respectively. In this paper, we analyzed microwave characteristics of TW-structure and found more accurate value of C and L by using finite difference time domain (FDTD) method. These values are adopted circuit element of equivalent circuit. Microwave characteristics obtained by the FDTD and equivalent circuit model show good agreement.

• Journal of the Korean Vacuum Society
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• v.19 no.6
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• pp.467-474
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• 2010

Packet propagation and absorption for the 28 GHz superconducting ECRIS under developing by KBSI Pusan center is analyzed with limited parameter range. The microwave power generated by 28 GHz gyrotron is axially injected to the plasma cavity through waveguide system. According to the analytical ray tracing calculation, the wave packet launched quasi-longitudinally at a high magnetic field side changes its direction from outward to inward as it is approaching resonance layer. Therefore, initially diverging wave does not likely hit a conducting surface before absorbing by electron cyclotron resonance. Also, absorption by plasma with moderate electron density is so strong that reflection by an extraction plate may not be expected.

• 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.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.75-77
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• 2003

마이크로파 방전을 이용한 고효율 고출력광원으로 연구 개발되고 있는 2-분자 발광체의 고압증기 플라즈마는 그 특성이 충분히 이해되지 않고 있다. 본 논문은 특유한 물리적 성질을 보이는 2-원자 황분자 증기 플라즈마의 물리적 성질과 광학적 특성에 관하여 총체적인 고찰을 할 것이다. 특히 고압 발광 플라즈마의 마이크로파 흡수 메카니즘 플라즈마 전도율, 및 발광 특성에 관하여 논의 할 것이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1169-1175
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• 1993

Plasma spraying method was used to fabricated the microwave absorbing ferrite-silicon carbide on the aluminum-alloy of the fuselage of an aircraft to protect it from RADAR detection. In this paper 15[rm] instead of 34[rm], the mean size of SIC-powder for ferrite-silicon carbide surface films(I) was used. 50(Kg/h) Instead of 70(Kg/h), the powder feed and 100[mm] Instead of 80(mm), spray distance of spray parameters was used. This M/W absorbers were designed experimentally and fabricated trially, as a result of which the relative frequency bandwidth of 2.8% were obtained under the tolerance limits of the reflection coefficients lower than-10[dB], and the maximum absorption thickness becomes 0.5[mm], which is much thinner than that of the conventional ones.

• Journal of the Korean Geotechnical Society
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• v.37 no.2
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• pp.5-17
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• 2021

The Moon has been an attractive planet as an outpost for deep space exploration since He-3 and water ice which can be used as energy resources were discovered. In-Situ Resource Utilization (ISRU) construction material fabrication method is required for sustainable space planet exploration. In this paper, the possibility of microwave sintering technology for construction material fabrication was evaluated using lunar regolith that can be easily collected from the Moon surface. Experimental assessment of the influence factors on microwave sintering was conducted using a hybrid sintering system for efficient processing. The heat distribution in the furnace was observed using thermal paper that is coated with a material formulated to change color when exposed to heat. Based on this result, sintered cylindrical KLS-1s with a diameter of 1 cm and a height of 2 cm were fabricated. Densities were measured for the sintered KLS-1s under rotating turntable conditions that have an effect of microwave dispersion. The more dielectrics were arranged, the more microwaves were dispersed reducing the heat concentration, and thus a uniformity of sintered KLS-1s was enhanced.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.2
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• pp.41-47
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• 1993

Electrical and electromagnetic wave absorbing properties of MnZn ferrite-rubber composites have been examined for varying the volume fraction of ferrite powder from 0.1 to 0.4 in the frequency range between 1-10 GHz. As the volume fraction of MnZn ferrite increased, the complex permittivity and permeability of composite increased. The peak of reflection loss at the frequency corresponding to 1/4 wavelength shifts to lower frequency, and shifts to lower frequency as the thickness of absorber increased. We show that for the ferrite-rubber composites the volume fraction of ferrite should be controled to obtain the absorbing properties required in given frequency range.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.653-659
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• 2005

When emulsion is irradiated by a microwave, the energy absorbed by the emulsion is proportional to irradiation time. In case of a long exposure, the temperature of emulsion rises, its viscosity decrease, and subsequently increase the rate of demulsification. In this work, in order to improve demulsification rate, the studies on demusification and the Sauter mean diameter ($D_{32}$) for each microwaved emulsion with different irradiation mode(continuous, pulsative, and periodical irradiation) have been carried out. When the 30% W/O emulsion (sample #1) was irradiated for 600 sec and settled for 24 h, oil recovery rates from continuous, pulsative, and periodical microwave irradiation were 60.0%, 62.3%, and 96.2%, and the amounts of separated water were 26.5%, 35.0%, and 93.9%, respectively. Also, the Sauter mean diameters ($D_{32}$) were $47.183{\mu}m$, $111.547{\mu}m$, and $220.476{\mu}m$, respectively.

• Clean Technology
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• v.21 no.3
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• pp.178-183
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• 2015

Lead molybdate (PbMoO₄) oxides were successfully synthesized using a conventional hydrothermal method and a microwave-assisted hydrothermal method. They were characterized by XRD, DRS, BET, Raman, SEM and PL. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamine B under UV-light irradiation. From XRD and Raman results, well-crystallized PbMoO₄ crystals have been successfully synthesized regardless of preparation method and had 42~59 nm particle size. The PbMoO₄ catalysts prepared using microwave-assisted process had the similar particle size and enhanced the photocatalytic activity when compared to that prepared by hydrothermal method. The PbMoO₄ catalysts prepared under the irradiation of microwave for 75 min showed the highest photocatalytic activity. The PL peaks appears at about 530 nm at all catalysts and it was also shown that the excitonic PL signal is proportional to the photocatalytic activity for the decomposition of Rhodamine B.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.156-157
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• 2001

전계 흡수 광 변조기는 우수한 소광비와 낮은 전력 소모로 넓은 대역폭을 확보할 수 있으며 LD와의 단일 집적인 EML(electro-absorption modulator integrated laser diode)의 제작도 용이하므로 Microwave-Photonics 시스템에 매우 적합한 소자로써 근래에 활발한 연구가 진행되어지고 있다. 전계 흡수 광 변조기의 대역폭을 최대한 확보하기 위해서는 진행하는 마이크로파의 위상속도와 광파의 그룹 속도가 정합 되어야 하며 소자의 임피던스가 50Ω에 정합 되어야 한다. (중략)