• 전기학회논문지P
• /
• 제60권2호
• /
• pp.76-81
• /
• 2011

Power system frequency is the main index of power quality indicating an abnormal state and disturbances of systems. The nominal frequency is deviated by sudden change in generation and load or faults. Power system is used as frequency relay to detection for off-nominal frequency operation and connecting a generator to an electrical system, and V/F relay to detection for an over-excitation condition. Under these circumstances, power system should maintain the nominal frequency. And frequency and frequency deviation should accurately measure and quickly estimate by frequency measurement device. The well-known classical method, frequency estimation technique based on the DFT, could be produce the gain error in accuracy. To meet the requirements for high accuracy, recently Wavelet transforms and analysis are receiving new attention. The Wavelet analysis is possible to calculate the time-frequency analysis which is easy to obtain frequency information of signals. However, it is difficult to apply in real-time implementation because of heavy computation burdens. Nowadays, the computational methods using the Wavelet function and transformation techniques have been searched on these fields. In this paper, we apply the Recursive Discrete Wavelet Transform (RDWT) for the frequency estimation. In order to evaluate performance of the proposed technique, the user-defined arbitrary waveforms are used.

• 한국환경과학회지
• /
• 제29권8호
• /
• pp.793-800
• /
• 2020

The conventional development of multi-component electrodes is based on the researcher's experience and is based on trial and error. Therefore, there is a need for a scientific method to reduce the time and economic losses thereof and systematize the mixing of electrode components. In this study, we use design of mixture experiments (DOME)- in particular a simplex lattice design with Design Expert^Ⓡ program- to attempt to find an optimum mixing ratio for a three-component electrode for the high RNO degradation; RNO is an indictor of OH radical formation. The experiment included 12 experimental points with 2 center replicates for 3 different independent variables (with the molar ratio of Ru, Ti, Ir). As the Prob > F value of the 'Quadratic' model is 0.0026, the secondary model was found to be suitable. Applying the molar ratio of the electrode components to the corrected response model results is an RNO removal efficiency (%) = 59.89 × [Ru] + 9.78 × [Ti] + 67.03 × [Ir] + 66.38 × [Ru] × [Ir] + 132.86 × [Ti] × [Ir]. The R² value of the equation is 0.9374 after the error term is excluded. The optimized formulation of the ternary electrode for an high RNO degradation was acquired when the molar ratio of Ru 0.100, Ti 0.200, Ir 0.700 (desirability d value, 1).

• Journal of Plant Biotechnology
• /
• 제1권1호
• /
• pp.8-12
• /
• 1999

New winter wheat winter barley hybrids were produced (Mv9 kr1 Igri, Mv9 kr1 Osnova, Asakazekomugi Manas). The wheat-barley hybrids showed entire male sterility and were multiplied in tissue culture. Chromosome configurations were studied with GISH in meiosis in the Mv9 krl x Igri hybrid and in its progenies multiplied in vitro. Chromosome pairing between wheat and barley has been observed in some cells in the hybrids multiplied in vitro. Backcross plants with 43 and 44 chromosomes were selected with the aim of developing new wheat-barley addition lines. Wheat-barley translocations were demonstrated with GISH in backcross progenies originating from in vitro regenerated wheat (Triticum aestivum L. cv. Chinese Spring) x barley (Hordeum vulgare L. cv. Betzes) hybrids. Five different translocations were observed. Sequential N-banding and GISH analyses were performed to further identify the translocations. The N-banding pattern of the Robertsonian translocation suggests that this chromosome consists of the short arm of barley chromosome 4H translocated to the long arm of 2B of wheat. Plants with four different homozygous translocations were selected from the following BC2F3 generation.

• 한국분무공학회지
• /
• 제2권4호
• /
• pp.15-21
• /
• 1997

In a gasoline engine with port injection system, the fuel behavior in the intake port has significant influence on the HC emission and the precise A/F control. That is to say, it is inevitable that the injection direction and behavior of fuel injected in the intake port have an effect on the generation of unburned HC within a cylinder. In this paper, we visualized fuel behavior in the intake port using micro CCD camera synchronized with the stroboscope and investigated the fuel-film characteristics formed at the wall of intake port by processing image captured with VCR in the transparent intake port made of acryl. Using these measuring methods, it was found that fuel behavior and the formation of fuel-film in the intake port could be evaluated qualitatively. And results obtained by these methods show that 2-spray injector minimizes the fuel-film formed in the intake port of a DOHC gasoline engine.

• Journal of Power Electronics
• /
• 제9권2호
• /
• pp.133-145
• /
• 2009

In this paper a modular high performance MV-to-LV rectifier based on a cascaded H-bridge rectifier is presented. The proposed rectifier can directly connect to the medium voltage levels and provide a low-voltage and highly-stable DC interface with the consumer applications. The input stage eliminates the necessity for heavy and bulky step-down transformers. It corrects the input power factor and maintains the voltage balance among the individual DC buses. The second stage includes the high frequency parallel-output DC/DC converters which prepares the galvanic isolation, regulates the output voltage, and attenuates the low frequency voltage ripple ($2f_{line}$) generated by the first stage. The parallel-output converters can work in interleaving mode and the active load-current sharing technique is utilized to balance the load power among them. The detailed analysis for modeling and control of the proposed structure is presented. The validity and performance of the proposed topology is verified by simulation and experimental results.

• 한국해양학회지
• /
• 제26권2호
• /
• pp.101-107
• /
• 1991

영산강 하구역에 분포하는 진주담치에 기생하는 요각류, Pseudomyicola spinosus 의 계절 변동을 조사했다. 본 종은 일년에 4세대를 영위하며 여름에 나타난 세대의 개 체수가 가장 많았다. 성비는 9월을 제외하고 6∼10월은 수컷이 1월을 제외한 11∼5월 은 암컷성체가 각각 우세하게 나타났다. 포란성체는 2월을 제외하고 연중 발견되었다. 포란성체가 많이 나타난 1개월 후에는 copeodid가 많이 출현하였다. copeodid는 1∼3 기는 전체의 약 4%에 불과하였으며, 이러한 결과는 copeodid 3기에 본격적인 감염이 이루어지고 있음을 시사하였다.

• Fisheries and Aquatic Sciences
• /
• 제15권1호
• /
• pp.43-47
• /
• 2012

Growth hormone (GH) transgenesis in fish has the potential to improve aquaculture efficiency and capacity. However, many fast-growing transgenic fish have experienced side effects caused by excess GH expression. To overcome this unwanted issue associated with several GH transgenic mud loach Misgurnus mizolepis lines carrying GH construct driven by a strong ${\beta}$-actin regulator ($pml{\beta}$-actGH), we performed an alternative version of GH autotransgenesis using a weaker but more stable regulator, the mud loach lectin promoter. GH transgenesis with a pmlectGH construct consisting of the mud loach GH gene driven by the 2.3-kb lectin promoter exhibited significant growth stimulation. However, the extent of the growth acceleration in pmlectGH transgenics (six times maximum when assessed 2 months post hatching) was much less than that in transgenic individuals carrying the $pml{\beta}$-actGH construct. Additionally, the extraordinary gigantism that was common in $pml{\beta}$-actGH-transgenic mud loaches was diminished in transgenic loaches harboring the pmlectGH construct. Transgenic founders (pmlectGH) successfully transmitted their transgene into the next generation with up to 41% frequency. Growth stimulation also persisted in the transgenic F1 strains, with a seven-fold increase in maximum body weight at 6 months of age.

• Nuclear Engineering and Technology
• /
• 제40권2호
• /
• pp.139-146
• /
• 2008

This paper presents two of the fuel channel designs being considered for the CANDU-SCWR, a pressure-tube type supercritical water cooled reactor. The first is an insulated pressure tube design. The pressure tube is thermally insulated from the hot coolant by a porous ceramic insulator. Each pressure tube is in direct contact with the moderator, which operates at an average temperature of about $80^{\circ}C$. The low temperature allows zirconium alloys to be used. A perforated metal liner protects the insulator from being damaged by the fuel bundles and erosion by the coolant. The coolant pressure is transmitted through the perforated metal liner and insulator and applied directly to the pressure tube. The second is a re-entrant design. The fuel channel consists of two concentric tubes, and a calandria tube that separates them from the moderator. The coolant enters between the annulus of the two concentric fuel channel tubes, then exits the fuel channel through the inner tube, where the fuel bundles reside. The outer tube bears the coolant pressure and its temperature will be the same as the coolant inlet temperature, ${\sim}350^{\circ}C$. Advantages and disadvantages of these designs and the material requirements are discussed.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.432-432
• /
• 2010

Organic light emitting diodes (OLED) thin films were fabricated by Electrostatic spray deposition (ESD). In this study, we reported the thickness, morphology, current efficiency, luminescence of OLED fabricated by ESD. These results were compared with the spin coating method, and showed that also ESD is a good fabrication method for OLED because of its characteristics similar with the results using spin coating. The active layer consists of organic blends with Poly(N-vinylcarbazole) (PVK), 2-(4-Biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), N,N'-Bis(3-methylphenyl) -N,N'-bis(phenyl)-benzidine (TPD), Tris(2-phenylpyridine)iridium(III) (Ir(ppy)3), and the structure of OLED consists of aluminum (Al), lithium fluoride (LiF), organic blends, PEDOT:PSS and Indium-tin-oxide (ITO), which was used as the top cathode, cathode interfacial layer, emitting layer and bottom anode, respectively. The results suggest that Electrostatic spray deposition is a promising method for the next generation of OLED fabrication since it has a probability fabricating large-area thin films.

• 한국재료학회지
• /
• 제29권2호
• /
• pp.121-128
• /
• 2019

Supercapacitors are attracting much attention in sensor, military and space applications due to their excellent thermal stability and non-explosion. The ionic liquid is more thermally stable than other electrolytes and can be used as a high temperature electrolyte, but it is not easy to realize a high temperature energy device because the separator shrinks at high temperature. Here, we report a study on electrochemical supercapacitors using a composite electrolyte film that does not require a separator. The composite electrolyte is composed of thermoplastic polyurethane, ionic liquid and fumed silica nanoparticles, and it acts as a separator as well as an electrolyte. The silica nanoparticles at the optimum mass concentration of 4wt% increase the ionic conductivity of the composite electrolyte and shows a low interfacial resistance. The 5 wt% polyurethane in the composite electrolyte exhibits excellent electrochemical properties. At $175^{\circ}C$, the capacitance of the supercapacitor using our free standing composite electrolyte is 220 F/g, which is 25 times higher than that at room temperature. This study has many potential applications in the electrolyte of next generation energy storage devices.