• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.10 no.3
• /
• pp.199-205
• /
• 2017

In a small cell base station used in densely populated areas, a dual polarized multiple antenna(MIMO) is mainly used to increase the cell capacity. This paper demonstrates a dual-polarization antenna with high cross-polarization discrimination(XPD) that can improve the capacity of a small cell using a dual polarization multiple antenna (MIMO). By using the symmetric structure and differential feeding, high XPD in all directions is achieved. In addition, a very similar radiation pattern is observed between each polarization. Because of high XPD and similar radiation pattern in all directions, proposed antenna is well adopted for small-cell multiple-input multiple-output(MIMO) system. Experimental results shows that the proposed antenna has a bandwidth of 180 MHz (2.51~2.7 GHz), a maximum gain of 4.5 dBi (3.5~4.5 dBi), and a half-power beam width of 85 degrees. In addition, average XPD of 26.4 dB in all directions, more than 13.8 dB increase than previous dual-polarization antennas which use single emitter by using different feeding or selectively use polarization through switching.

• Journal of Energy Engineering
• /
• v.8 no.4
• /
• pp.553-559
• /
• 1999

This study has been implemented to investigate various characteristics of coals which are imported from abroad. KIER has developed 1 T/D bench-scale unit, entrained-flow coal-slurry gasification technology to investigate the followings: 1) to assess the appropriate foreign coals for gasification. 2) to establish the data base for gasification phenomena, 3) to minimize the technical risks prior to introduction of commercial scaled IGCC power plant, 4) to develop essential key technologies and to establish operational experiences for coal gasification. The foreign coals used in the gasification are Cyprus and Alaska coals from U. S. A. Cyprus coal(bituminous) and Alaska coal (lignite) were shown about 1.29$0^{\circ}C$. The concentrations of coal-slurry for Cyprus were maintained up to 58%, 62% and 65% in order to enable to feed satisfactorily it into the gasifier without any other problems at feeding systems. However, the Alaska coal was unable to maintain slurry concentration over the 60% due to its high viscosity. During the experiments, $O_2/coal$ ratios in both coals ere maintained from 0.6~1.2, but especially Alaska coal was required excessive oxygen feed due to its high ingerent moisture contents. During the experiments with two different coals, the concentrations of syngas $(H_2+CO)$ were shown as 40~62%, and the heating value of syngas were detected as 1,400~2,050 kcal/N㎥

• Cartoon and Animation Studies
• /
• s.25
• /
• pp.109-132
• /
• 2011

The Vampire has relatively universal images in through the cultural and verbal usages. The comic Higajima and movie display the latest image of Japanese Vampire of asian mode of production. After the Meiji political reformation of 18th Century, Japanese had rapidly changed into European style in every places. However, the Higajima is denied the structural changes, it is insisted that the changing is only the skin deep and colour of hair but the structure of the society is same as feudal Japan. Asian mode of production is claimed by Karl Marx, according to him, it is before the historical developing model in Europe and it was controversial. The major character of modern Japanese history would be the change of hierarchy of king-shogun-samurai-peasant based on the regional ground. The feudal structure is changed by the Meiji reformation and Japan was rushed for the westernized country rather than the asian mode of production. However, Higajima argued that the changing is just the clothes of ruler but the democracy and individual citizenship was lost in that reformation. Vampire is cursed creature that cannot see the sun and it has not the functioned as a human organ. For human it is dead but this creature actively moves and stronger than human and much superior than human in every aspects. It is managed the feeding through the suck the human blood and power to seduction. Even it is not exist, it is quite symbolic phenomenon of cultural usage of superior entity of chain of feeding. The aim of this paper is display the symbolic code Vampire of Asian mode of production in Higajima and political struggling of Japan in actual. To search of the cultural meaning and possibility of the Korean solution of modernity.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.6
• /
• pp.95-104
• /
• 2003

The electric traction systems are quite differ from general power systems which is single-phase and heavy load. Therefore, there are inevitably power quality problems such as steady state or transient voltage drop, voltage imbalance and harmonic distortion. Among these problems, since steady-state volatge drop is the one of most important factor in electric power quality, many researches about on the compensation of volatge drop by using SVC(Static Var Compensator) and/or STACOM(Static Compensator) have been studied and proposed Also, it is expected that transient voltage drop(voltage sag) could affect the control and safety of high speed traction load. In this paper, voltage sag compensation of AT(Auto Transformer) feeding system are studied The detailed transient models of utility source, scott transformer, AT, and traction load are estabilished. The application of DVR(Dynamic Voltage Restorer) in electric traction system is proposed to compensate the voltage sag of traction network which is occured by the fault of utility source. It can be shown that application of the DVR in electric traction system is very useful to compensate the volatge sag from the result of related simulation works.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.7
• /
• pp.683-693
• /
• 2011

In this paper, a design of high current and broad-band microwave bias-tee was presented for a stable bias of a high power amplifier. An input impedance of bias-tee should be shown to 50 ohm with the wideband in order to be stably-biased the amplifier. For this design of the bias-tee, a capacitor of bias-tee for a DC block was designed with a high wide-band admittance by a parallel sum of capacitors, and a inductor for a RF choke and a DC feeding was designed with a high wide-band impedance by a series sum of inductors. As this inductor and capacitor for the sum has each SRF, band-limitation of lumped element was driven from SRF. This limitation was overcome by control of a resonance's quality factor with adding a resistor. 1608 SMD chips for design's element was mounted on the this pattern for the designed bias-tee. The fabricated bias-tee presented 10 dB of return loss and wide-band about 50 ohm input impedance at 10 MHz~10 GHz.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.146-147
• /
• 2011

Processing a large area substrate for liquid crystal display (LCD) or solar panel applications in a capacitively coupled plasma (CCP) reactor is becoming increasingly challenging because of the size of the substrate size is no longer negligible compared to the wavelength of the applied radio frequency (RF) power. The situation is even worse when the driving frequency is increased to the Very High Frequency (VHF) range. When the substrate size is still smaller than 1/8 of the wavelength, one can obtain reasonably uniform process results by utilizing with methods such as tailoring the precursor gas distribution by adjustingthrough shower head hole distribution or hole size modification, locally adjusting the distance between the substrate and the electrode, and shaping shower head holes to modulate the hollow cathode effect modifying theand plasma density distribution by shaping shower head holes to adjust the follow cathode effect. At higher frequencies, such as 40 MHz for Gen 8.5 (2.2 m${\times}$2.6 m substrate), these methods are not effective, because the substrate is large enough that first node of the standing wave appears within the substrate. In such a case, the plasma discharge cannot be sustained at the node and results in an extremely non-uniform process. At Applied Materials, we have studied several methods of modifying the standing wave pattern to adjusting improve process non-uniformity for a Gen 8.5 size CCP reactor operating in the VHF range. First, we used magnetic materials (ferrite) to modify wave propagation. We placed ferrite blocks along two opposing edges of the powered electrode. This changes the boundary condition for electro-magnetic waves, and as a result, the standing wave pattern is significantly stretched towards the ferrite lined edges. In conjunction with a phase modulation technique, we have seen improvement in process uniformity. Another method involves feeding 40 MHz from four feed points near the four corners of the electrode. The phase between each feed points are dynamically adjusted to modify the resulting interference pattern, which in turn modulate the plasma distribution in time and affect the process uniformity. We achieved process uniformity of <20% with this method. A third method involves using two frequencies. In this case 40 MHz is used in a supplementary manner to improve the performance of 13 MHz process. Even at 13 MHz, the RF electric field falls off around the corners and edges on a Gen 8.5 substrate. Although, the conventional methods mentioned above improve the uniformity, they have limitations, and they cannot compensate especially as the applied power is increased, which causes the wavelength becomes shorter. 40 MHz is used to overcome such limitations. 13 MHz is applied at the center, and 40 MHz at the four corners. By modulating the interference between the signals from the four feed points, we found that 40 MHz power is preferentially channeled towards the edges and corners. We will discuss an innovative method of controlling 40 MHz to achieve this effect.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.36 no.8
• /
• pp.965-974
• /
• 2007

This study was performed to investigate the effects of vegetable sprout powder on serum and adipose tissue lipid metabolism in rats fed high-fat diet for 4 weeks for induction hyperlipidemic model rat. Weight-matched male Sprague-Dawley rats were assigned to five groups according to dietary fat level (10% or 20% of diet wt.) and mixture of vegetable sprout powder levels (5% or 10% 10% or 20% of diet wt.). Vegetable sprout powder was the mixture of same amounts of dried barley, broccoli, rapeseed, alfalfa, radish, mustard, buckwheat and brussels sprouts. Experimental groups were normal fat diet with 5% cellulose (NF-C), high fat diet without fiber (HF-N), high fat diet with 5% cellulose (HF-C), HF-C diet with 5% vegetable sprout powder (HF-CSL), and HF-C diet with 10% vegetable sprout powder (HF-CSH). The body weight of HF-N group increased 16% compared with the NF-C group, while it was decreased by 15% and 22% for HF-CSL group and HF-CSH group, respectively. Fat mass and fat cell size of adipose tissue were lower in HF-CSL group and HF-CSH group compared with HF-C group, and lower in HF-CSH group compared with HF-CSL group. Serum triglyceride, total cholesterol and LDL-cholesterol contents were markedly decreased by vegetable sprout powder containing diet, while the serum HDL-cholesterol and phospholipid contents were higher in vegetable sprout powder containing diet in a dose-dependent manner. Leptin and insulin levels in serum showed a decrease in HF-CSH group. Significantly increased contents of triglyceride, total cholesterol, LDL-cholesterol, leptin and insulin in the serum of HF-N group were returned to normal or even below normal levels by feeding 10% vegetable sprout powder diet. The increased activities of NADP-malate dehydrogenase (ME), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) and lipoprotein lipase (LPL) in adiposetissue by HF-N group were decreased to the activity of normal fat group by feeding vegetable sprout powder in a dose-dependant manner. These results indicate that lipid metabolism in rats fed high-fat diet was suppressed by feeding vegetable sprout powder.

• Polymer(Korea)
• /
• v.29 no.6
• /
• pp.549-556
• /
• 2005

Effects of the dimensionless variables on the heat transport phenomena in the extrusion process of a single screw extruder have been studied numerically. Based on the understanding of the solids conveying related to the geometrical structure and characteristics of the screw, the heat balance equation for the solids conveying zone was established and normalized. The finite volume method and power-law scheme were applied to derive a discretized equation and the equation was solved using the alternating direction iterative method with relaxation. Effects of the dimensionless parameters, Biot and Peclet numbers, that define the heat transfer characteristics of the solids conveying zone have been investigated with respect to the temperature of the feeding zone and the length of the solids conveying zone. As the Biot number is increased, the heat loss by cooling dominates to decrease the temperature of the barrel but it has little effects on the temperature of the solids bed and the length of the solids conveying zone. On the other hand, if the Peclet number is increased, the convection term dominates to decrease the temperature of the solids bed and it results in an increase in the length of the solids conveying zone.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.3
• /
• pp.286-291
• /
• 2013

In this paper, a compact rectenna system is designed using a circular sector antenna with harmonic-rejecting characteristics and a direct impedance matching method. The system is designed with bandpass filtering performed by the harmonic-rejection of the circular sector antenna and without impedance matching circuit for the diodes by the direct impedance matching technique. Therefore, while the rectifying circuit of the proposed system can be implemented without a bandpass filter and a impedance matching circuit, it is integrated on the back side of the antenna using precise fabrication techniques for coaxial feedings without degrading the system performances corresponding to the feeding points. From the experimental results, the optimized rectenna system has presented excellent performances of a conversion efficiency of more than 52 % and a conversion voltages of more than 1.5 V at 2.5 GHz.

• Journal of Electrochemical Science and Technology
• /
• v.8 no.4
• /
• pp.265-273
• /
• 2017

Solid-state alkaline water electrolysis is a promising method for producing hydrogen using renewable energy sources such as wind and solar power. Despite active investigations of component development for anion exchange membrane water electrolysis (AEMWE), understanding of the device performance remains insufficient for the commercialization of AEMWE. The study of assembled AEMWE devices is essential to validate the activity and stability of developed catalysts and electrolyte membranes, as well as the dependence of the performance on the device operating conditions. Herein, we review the development of catalysts and membranes reported by different AEMWE companies such as ACTA S.p.A. and Proton OnSite and device operating conditions that significantly affect the AEMWE performance. For example, $CuCoO_x$ and $LiCoO_2$ have been studied as oxygen evolution catalysts by Acta S.p.A and Proton OnSite, respectively. Anion exchange membranes based on polyethylene and polysulfone are also investigated for use as electrolyte membranes in AEMWE devices. In addition, operation factors, including temperature, electrolyte concentration and acidity, and solution feed methods, are reviewed in terms of their influence on the AEMWE performance. The reaction rate of water splitting generally increases with increase in operating temperature because of the facilitated kinetics and higher ion conductivity. The effect of solution feeding configuration on the AEMWE performance is explained, with a brief discussion on current AEMWE performance and device durability.