• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.3
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• pp.240-245
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• 2013

Each pixel of InfraRed(IR) sensor differently responds to IR light as time elapses or the sensor on/off operation is repeated. As a result, the quality of IR sensor image is deteriorated, and therefore NUC(Non-uniformity Correction) is periodically needed for IR sensor. In this paper, in order to perform NUC in the Satellite, on-board V-grooved blackbody is designed with a baffle so that the emissivity of black body is to be higher than 0.995 as well as the temperature deviation is less than $1^{\circ}C$ in the range of the infrared wave length from 3.3 to $5.2{\mu}m$. To check its performance, the emissivity and the surface temperature of the blackbody by TRT(Transfer Reference Thermometer) and IR Micrometer scanner are measured, respectively. From the results, black body design is verified and the uncertainty of NUC is estimated through the measurement results.

• Journal of the Korean Society of Fashion and Beauty
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• v.4 no.3 s.9
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• pp.13-17
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• 2006

Perm is one the of the most common thing in a beauty salon like hair-cut and hair perm needs processing solutions which is chemical substances. Those chemical substances damage the hair cuticle. Damaged hair cuticles with mistakes of perm will follow with the next performance and it will cause more damage to hair. As damage of hair cuticle become worse, it is harder to recover the hair cuticle like before. Therefore, this study shows that plain rinse is the way to reduce the damage of hair cuticle with perm as much as possible. With experiments, I suggest the right way to do plain rinse to satisfy customers' demand and reduce the damage. During the research, I figured that plain rinse with the knowledge, structure of hair cuticle, principle of perm and plain rinse, is very needed. The hair with plain rinse have more elastic curl and have less scales which came off from hair cuticle than the hair without plain rinse. This experiment concludes that hairdresser has to figure out about the time, temperature and type of water depends on the degree of damaged hair of customers. In order to perm, there is no way to not to use chemical substances to perm. Therefore, hairdresser has to choose suitable processing solutions and right steps, and as this is the age of 'well-being' boom, hairdresser must try to keep the healthy hair. Consequently, in order to meet the demands and conditions of customers, hairdresser needs to find the right method to do plain rinse and use the method in perm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.9
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• pp.691-701
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• 2020

An actuator mixer design using convex optimization technique situation where the propulsion system of an electric VTOL UAV during vertical take-off and landing maneuvers is proposed. The attainable control set to analyze the impact from failure of each motor and propeller can be calculated and illustrated using the properties of the convex function. The control allocation can be defined as a convex function optimization problem to obtain an optimal solution in real time. The mixer is implemented using a convex optimization solver, and the performance of the control allocation methods is compared to the attainable control set. Finally, the proposed mixer is compared with other techniques with nonlinear sux degree-of-freedom simulation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.1
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• pp.51-65
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• 2002

This paper presents a design method of the neural network-based controller using an indirect adaptive control method to deal with an intelligent control for chaotic nonlinear systems. The proposed control method includes the identification and control Process for chaotic nonlinear systems. The identification process for chaotic nonlinear systems is an off-line process which utilizes the serial-parallel structure of multilayer neural networks and simple state space neural networks. The control process is an on-line process which uses the trained neural networks as the system model. An error back-propagation method was used for training of identification and control for chaotic nonlinear systems. The performance of the proposed neural network controller was evaluated by application to the Duffing equation and the Lorenz equation, and the proposed controller was compared with other neural network-based controllers by computer simulations.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.25-34
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• 2000

This paper describes design of a 250-Mbps 10-channel optical receiver array for parallel optical interconnection with the general-purpose CMOS technology The optical receiver is one of the most important building blocks to determine performance of the parallel optical interconnection system. The chip in CMOS technology makes it possible to implement the cost-effective system also. Each data channel consists of analog front-end including the integrated photo-detector and amplifier chain, digital block with D-FF and off-chip driver. In addition, the chip includes PLL (Phase-Lock Loop) for synchronous data recovery. The chip was fabricated in a 0.65-${\mu}{\textrm}{m}$ 2-poly, 2-metal CMOS technology. Power dissipation of each channel is 330㎽ for $\pm$2.5V supply.

• Composites Research
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• v.29 no.6
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• pp.369-374
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• 2016

In this study, a structural optimal design of 10 MW composite blade was performed using bend-twist coupled(BTC) design concept. Bend-twist coupling of blade means the coupling behavior between the bending and torsional deflections due to the composite lamina with fiber angle biased from the blade longitudinal axis. This can potentially improve the overall performance of composite blade and reduce the dynamic loading. Parametric studies on layup angle, thickness and area of off-axis carbon UD were conducted to find the optimum coupling effect with weight reduction. Comparing the results of fatigue load analysis between conventional model and BTC applied model, the damage equivalent load(DEL) of blade root area were decreased about 3% in BTC model. To verify the BTC effect experimentally, a 1:29 scaled model was fabricated and the torsion at the tip under deflection behavior of blade stiffener model was measured by static load test.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.5
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• pp.72-79
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• 2010

In this paper, we describe the design and implementation of a high efficiency Doherty power amplifier using gallium nitride (GaN) high-electron mobility transistor (HEMT). The carrier and peaking amplifiers of the proposed Doherty power amplifier consist of the switching-mode Class-E power amplifiers. The test conditions are a duty of 10% and a pulse width of $100\;{\mu}s$ and pulse repetition frequency (PRF) of 1 kHz for a S-band radar application. A RF performance peak PAE of 64% with drain efficiency of 80.6%, at 6 dB output back-off point from saturated output power of 45.5 dBm, was obtained at 2.85 GHz.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.47-54
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• 2016

In the underwater environment, high resolution can be achieved in the range direction by transmitting and receiving a signal of a particular band and/or waveform. The design of a transmit signal used in the active sonar is very important in order to detect a cylindrical object within a short distance less than 1 km, which is the detection distance of this paper. Designing a transmit signal optimal to a sonar requires appropriate selection of its center frequency and bandwidth, which allows the maximum detection distance of a sonar. In this paper, in terms of maximizing echo excess and signal to noise ratio (SNR), optimum frequency analysis is carried out under various conditions of diverse parameters. In addition, the investigation focused on the determinating a bandwidth is also performed for the purpose of satisfying the performance requirement of range resolution and azimuth resolution.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.705-712
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• 2001

In this paper, a new type of aperture coupled microstrip patch antenna with tilted-beam based on the principal of the dipole yagi antenna is proposed and investigated experimentally. Its configuration is composed by 3 types of patches; reflector, driver, and director. Tilted beam patterns are effected by many parameters as those of dipole yagi antenna; sizes of the patches, gaps between the patches, characteristics of the substrates, feeding method and etc. Therefore, in this paper, the effects of varying design parameters of this antenna are studied with a goal of enhancing the gain and tilting the beams. A microtrip patch antenna with tilted beam based on performance trade-offs is designed and fabricated. Measured and simulated results for return loss and radiation patterns are presented. It has 45$^{\circ}$ tilted beam and very close to simulation beam pattern at resonant frequency, 2.58 GHz.

• Composites Research
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• v.17 no.3
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• pp.15-22
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• 2004

Acoustic load generated by rocket propulsion system is one of major dynamic loads during lift-off phase so that it causes the structural failure and electronic malfunction of payloads. Acoustic loads can be greatly reduced by an appropriate acoustical design of nose faring structures. This paper deals with the acoustical design of the nose fairing structure for launch vehicle. It is well known that a honeycomb sandwich structure is a poor sound insulator because of its high specific stiffness. In this paper, the sound transmission characteristics of four kinds of honeycomb structures for noise fairing were investigated by means of numerical and experimental ways. In order to estimate transmission loss, infinite plate theory by Moore and Lyon and statistical energy analysis (SEA) method were used. The predicted results showed a good agreement with measured ones. These enabled us to determine a proper core material for nose fairing, which shows good sound insulation performance per weight.