• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.04a
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• pp.33-37
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• 1994

When a bolt is tightened up to the range of plastic deformation, yielding is governed by the combined stresses due to the axial force developed in the bolt and the frictional torque developed on the thread in contact with the nut. Consideration is taken account of the fact that the unused portion of the thread has least sectional area being subject to initial yielding. Once yielding has taken place some strain hardening effect will result, Incremental stress-strain relations are used to treat the continued yielding, which is equivalent to treat continued yielding as if summing up the effects of thin walled cylinders subject to plastic deformation. M10 bolts of common and fine series thread are used for computational purposes. Variation of axial forces and frictional torques vs. the frictional coefficients tare presented together with other plots showing some characteristics of bolt under plastic deformation.

• Proceedings of the KIEE Conference
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• 1984.07a
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• pp.92-95
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• 1984

This paper describes a general method for the design of variable structure Model-Following Control systems (VSMFC). This design concept is developed using the theory of variable structure systems and slide mode. The feasibility and the advantages of the method are illustrated by applying it to a 1000 MWe Boiling Water Reactor. The control is studied in the range of 85 - 90 % of rated power for load-following control. A set of 12 nonlinear differential eq. are used to simulate the total plant. A 6th order linear model has been developed from these equations at 85% of rated power. The obtained controller is shown by simulations to be able to compensate for a plant parameter variation over a wide power range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.451-454
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• 2002

A silicone rubber has been used so many dielectric materials for extremely high voltage(EBW) electric appliances. The reason why it is very stable in the thermal, mechanical and electrical environment. In this paper, we have studied the dependence of dielectric characteristics of silicone rubber on frequency-dependent variation. The dielectric characteristics were measured in the temperature range of 25[$^{\circ}C$] and 150[$^{\circ}C$]. Also we measured in the voltage range of 1[V] and 20[V]. The energy of activation on the dielectric loss obtained 2.44[kcal/mol], 2.1[kcal/mol], 1.63[kcal/mol] and 1.57[kcal/mol] by appling respectively.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1306-1308
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• 1998

Diamond like carbon(DLC) thin films possesed not only marvelous material charateristics such as large thermal conductivity, high hardness and being chemically inert, but also possesed negative electron affinity(NEA) properties. The NEA is an extremely desirable property of the material used in microelestronics and vacuum microelestronics device. DLC films were fabricated by pulsed laser deposition(PLD). The effect of the laser energy density and the substrate temperature on the properies of DLC films was investigated. The experiment was accomplished at temperatures in the range of room temperature to $400^{\circ}C$. The laser energy density was in the range of $6 J/cm^2$ to $16 J/cm^2$.

• Journal of Photoscience
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• v.9 no.1
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• pp.23-28
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• 2002

In order to obtain thermal-stable, low birefringent, and low optical loss waveguiding materials, we synthesized several fluorinated poly (maleimide-co-glycidylmethacrylate)s using a pentafluorophenylmaleimide (PEM) and two kinds of methacrylate derivatives as comonomers and glycidylmethacrylate as a crosslinker. One comonomer is a linear fluorinated methacrylate (HFBM) and another is a bulky norbornane-derived methacrylate (NMMA). These copolymers could be self-crosslinked by heating due to epoxy groups of glycidylmethacrylates. As a maleimide contents increased to 50 mol%, these copolymers showed high decomposition temperatures of above 300$^{\circ}C$. The refractive index could be precisely controlled by the variation of PFM/HFBA or PFM/NMMA feed ratio in the range of 1.410∼1.508 at 643 nm. The copolymers had very low birefringence in the range of 1∼5${\times}$10$\^$-4/.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.241-246
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• 2007

This paper presents two novel compensation circuits for leakage current and power supply noise (PSN) in phase locked loop (PLL) using a nanometer CMOS technology. The leakage compensation circuit reduces the leakage current of the charge pump circuit and the PSN compensation circuit decreases the effect of power supply variation on the output frequency of VCO. The PLL design is based on a 32nm predictive CMOS technology and uses a 0.9 V power supply voltage. The simulation results show that the proposed PLL achieves 88% jitter reduction at 440 MHz output frequency compared to the PLL without leakage compensator and its output frequency drift is little to 20% power supply voltage variations. The PLL has an output frequency range of 40 $M{\sim}725$ MHz with a multiplication range of 1-1023, and the RMS and peak-to-peak jitter are 5psec and 42.7 psec, respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.301-306
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• 2008

A pyrogen igniter was designed to satisfy the required condition of kick motor system for the space launch vehicle. We analyzed the ignition characteristics and performed the combustion tests to verify the internal ballistic performance. In the design process, the arc-image test was carried out to find the sufficient heat flux as varying the initial pressure from 10 to 700kPa. The analysis indicated that the initial pressure condition would delay ignition time within a range from 100 to 500ms. The combustion test with an inert chamber was also performed to understand the ignition characteristics with the variation of the initial pressure of free chamber volume. Finally, we confirmed that the igniter could provide the acceptable energy to ignite the propellant of kick motor at the ground test. The result of the ground tests showed that the ignition delay time was within the design range at the atmospheric pressure condition.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.36-40
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• 2017

In this paper, a new method of laser trimming of thick film heater is studied. Various laser waves (IR, Green, UV) are used to ablation the heater and the process parameters are also presented. For given initial printed resisters, the cutting length should be prepared to obtain the target resister value in advance. Therefore, the cutting model is very important. The well-known model was tested and proven that it is valid only within a certain range of cutting length. A new model is proposed for a wide range of resister laser trimming. The cutting lengths and resister variation was obtained and formulated. To verify the presented method, the cutting lengths of each resister are calculated for various target resister value and laser trimming using UV is conducted.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.3
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• pp.251-261
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• 2006

The purpose of this study is to quantitatively estimate the settling property for fine-cohesive sediments in Keum Estuary and to evaluate the spatial variation by analyzing and comparing the local and seasonal variation of the settling properties in Keum Estuary with that of the settling properties in the other sites. After the spatial variation of physico-chemical properties such grain size distribution, the percentage of organic contents, mineralogical composition etc is investigated through experiments and analyses, interrelation between the physico-chemical properties and settling velocities and effect that the physico-chemical properties have on the quantitative variation of settling velocities were also analyzed in this study. Experimental results of settling tests shows that settling velocities of Keum Estuary mud vary in the range of two orders of magnitude (from 0.01 to 1mm/sec) over the corresponding concentration range of 0.1 to 80 g/L, and a feature of settling velocity profile is quite different in quantity as compared to those of previous studies with mud of other regions: Saemankuem, Tampa Bay, Sevem Estuary and lake Okeechobee. However, their local and seasonal variabilities within Keum Estuary appear to be insignificant.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.1
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• pp.10-16
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• 2016

In this paper, a design for a fully digital voltage sensor using a 32-nm fin-type field-effect transistor (FinFET) is presented. A new characteristic of the double gate p-type FinFET (p-FinFET) is examined and proven appropriate for sensing voltage variations. On the basis of this characteristic, a novel technique for designing low-power voltage-to-time converters is presented. Then, we develop a digital voltage sensor with a voltage range of 0.7 to 1.1V at a 50-mV resolution. The performance of the proposed sensor is evaluated under a range of voltages and process variations using Simulation Program with Integrated Circuit Emphasis (SPICE) simulations, and the sensor is proven capable of operating under ultra-low power consumption, high linearity, and fairly high-frequency conditions (i.e., 100 MHz).