• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.155-158
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• 2009

This study was investigated to know the thermal decomposition and measure the reaction time and temperature by EIDS cook-off test for the propellant ingredients and 2 kinds of HTPE propellants. The thermal analysis of the propellant ingredients used in this study showed that the thermal stability of these materials decreases in the following order : AP > HTPE > AN > BuNENA. In addition, propellant HTPE 002 containing AN showed that an endothermic process at around $125^{\circ}C$ corresponding to the solid`solid phase change($II{\rightarrow}I$) of AN was followed by the exothermic process due to decomposition of BuNENA/AN until $200^{\circ}C$. HTPE 001 and HTPE 001 reacted at around $250^{\circ}C$ and $152^{\circ}C$ each other, and the temperature of them sharply increased at $115^{\circ}C$ from EIDS slow cook-off tests.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.3
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• pp.30-39
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• 2011

In this note, a systematic design of a new robust nonlinear continuous variable structure control system(VSCS) based on the modified state dependent nonlinear form is presented for the control of uncertain affine nonlinear systems with mismatched uncertainties and matched disturbance. After an affine uncertain nonlinear system is represented in the form of state dependent nonlinear system, a systematic design of a new robust nonlinear VSCS is presented. The uncertainty of the nonlinear system function is separated into the tow parts, i.e., state dependent term and state independent term for extension of target plants. To be linear in the closed loop resultant dynamics and in order to easily satisfy the existence condition of the sliding mode, the transformed linear sliding surface is applied. A corresponding control input is proposed to satisfy the closed loop exponential stability and the existence condition of the sliding mode on the linear transformed sliding surface, which will be investigated in Theorem 1. For practical application, the discontinuity of the control input as the inherent property of the VSS is improved dramatically. Through a design example and simulation studies, the usefulness of the proposed controller is verified.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.3 s.357
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• pp.59-64
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• 2007

This paper describes the PLL of TCON(Timing Controller) chip for FPD(Flat Panel Display). We propose a new V-I converter which is insensitive to the power supply variation when it is applied to the TCON. The new V-I converter compensated the output frequency of VCO by appling the current that is inversely proportional to the voltage variation. The proposed idea is implemented with a 1-ploy 3-metal 0.25m TSMC CMOS technology and has the output frequency range from 192MHz to 360MHz at the supply voltage of 2.5V. Measurement result shows the RMS jitter of 100ps in the above output frequency range.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.709-716
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• 2016

In this paper, A duplexer module with temperature-insensitive electrical characteristics was proposed for remote wireless communication system. Duplexer modules are required to have performances of low insertion loss, high isolation between transmitted band and received band, harmonic suppression as well as high power durability in the system for transmitting guided information to missile flying a free space on the ground. The proposed duplexer module are consist of transmission bandpass filter and receiving bandpass filter which are connected to common antenna port, planar coupler for output power monitoring and low pass filter for harmonic attenuation of power amplifier and coaxial cavity resonator. The material and dimensions of the resonator are determined for minimum frequency shift by temperature variation using 3D EM simulation. The measured results of the prototype showed a good agreement with the simulation results, and it should be well applied not only for guided weapon systems but also for any other communication systems such as remote radio head.

• Journal of the Korean School Mathematics Society
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• v.17 no.4
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• pp.589-611
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• 2014

Since most people experience mathematics anxiety(MA), the research on mathematics anxiety has been the main theme in the research of mathematics education. The study of brain science related to MA has recently been begun due to the advent of apparatuses so this study might have revisited MA as time passed and aimed to obtain realistic implications for the future study. For this purpose, we analyzed previous studies how to measure MA and how to develop the intervention to reduce MA. As the result, the researchers based on brain science studied the relevance of specific parts of the brain according to the degree of MA using only simple computational tasks. The research for developing the MA scale has upgraded how to measure both the cognitive and affective domains with more efficient ways. The research on intervention for MA has developed the programs using systematic desensitization, clinical counseling, STAD teaching method, writing methods, etc. However, we realized that more specified and reliable studies to solve the MA must be done in the future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.535-543
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• 2014

In the robust optimization field, the robustness of the objective function emphasizes an insensitive design. In general, the robustness of the objective function can be achieved by reducing the change of the objective function with respect to the variation of the design variables and parameters. However, in conventional methods, when an insensitive design is emphasized, the performance of the objective function can be deteriorated. Besides, if the numbers of the design variables are increased, the numerical cost is quite high in robust optimization for nonlinear programming problems. In this research, the robustness index for the objective function and a process of robust optimization are proposed. Moreover, a method using the supremum of linearized functions is also proposed to reduce the computational cost. Mathematical examples are solved for the verification of the proposed method and the results are compared with those from the conventional methods. The proposed approach improves the performance of the objective function and its efficiency.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.1-8
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• 2008

Shack-Hartmann sensors are widely employed as a wavefront measuring device in various applications. Adaptive optics is one of the major applications. Since an adaptive optics system should be operated in real-time, high-speed wavefront sensing is essential. In high-speed operation, integration time of an image detector is very short. In this case, noises such as readout noise and photon noise greatly influence the accuracy of wavefront sensing. Therefore a fast and noise-insensitive centroid finding algorithm is required for the real-time wavefront sensing. In this paper, the multi-resolution correlation method is proposed. By employing multi-resolution images, this method greatly reduces the computation time when compared to the fast Fourier transform (FFT) correlation method. The verification is performed through the computational simulation. In this paper, the center of mass method, correlation method and multi-resolution correlation method are employed to compare the measurement accuracy of the centroid finding algorithms. The accuracy of a Shack-Hartmann wavefront sensor using the proposed algorithm is proved to be comparable to that of the conventional correlation method.

• Applied Biological Chemistry
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• v.29 no.1
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• pp.78-82
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• 1986

Panax ginseng seedlings were grown in vermiculite with nutrient solution different in nitrogen, phosphorus ana potassium level. Ginsenoside contents of root were investigated by high performance liquid chromatogram. Elimination or increase of one of N.P.K. increased or decreased total saponin content. Nitrogen was most effective (15.5% for-N to 8.9% for 3N) and potassium least. Similar trend was shown in each ginsenoside. According to coefficient of variation in one nutrient treatment or among all nutrient treatments ginsenoside Re was most insensitive to nutrient change and also other environmental factors and Rd most sensitive. Diol content (PD) was more variable than triol (PT) and variation of PT/PD was about half of them. Variation of ginsenoside content by nutrient change had no relation with the ginsenoside content. Similarity of ginsenoside pattern slightly decreased with the difference of saponin content by nutrient change. Root weight was significantly small only in tap water plot.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.375-378
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• 2013

A reference voltage generator which is insensitive to PVT (process-voltage-temperature) variation necessary for NVM memory IPs such as EEPROM and MTP memories is designed in this paper. The designed BGR (bandgap reference voltage) circuit based on MagnaChip's $0.18{\mu}m$ EEPROM process uses a low-voltage bandgap reference voltage generator of cascode current-mirror type with a wide swing and shows a reference voltage characteristic insensitive to PVT variation. The minimum operating voltage is 1.43V and the VREF sensitivity against VDD variation is 0.064mV/V. Also, the VREF sensitivity against temperature variation is $20.5ppm/^{\circ}C$. The VREF voltage has a mean of 1.181V and its three sigma ($3{\sigma}$) value is 71.7mV.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.41-46
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• 2020

In this study, measurement and analysis results from Differential scanning calorimetry(DSC) and Thermogravimetric analysis(TGA) on the newly developed high-energy thermoplastic elastomer(ETPE) propellant are described, followed by the previous study done under the same title as this paper [1]. The characteristics of high-energy thermoplastic propellant were also verified by conducting thermal analysis, and the LSGT, Shotgun & RQ Bomb test, was carried out as well. High energetic thermoplastic binders containing 45% of GAP(Glycidyl Azide Polymer), energetic plasticizer(DEGDN) and Oxidizer Aonium Perchlorate), RDX(reseach development explosive, cyclotrimethylenetrinitramine) were used to formulate the propellant.