• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.590-593
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• 2002

Using two- and three-dimensional fluid simulation codes, we have suggested several new plasma display panel (PDP) cell structures that have high luminous efficiency compared with conventional structure. To improve the luminance and discharge efficiency, we utilize long discharge path, lower electric field region, and reduction of power consumption by adding one auxiliary electrode or reducing the electrode area. Consequently, luminous efficiency increases about 1.8 times. Furthermore for the resonance radiation trapping effect in PDP system, we have described a self-consistent radiation transport model coupled with fluid simulation using modified Holstein's equation.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.873-881
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• 2014

Speed sensorless modes of operation are becoming standard solution in the area of electric drives. This paper presents flux estimator and speed estimator for the speed sensorless vector control of induction motors. The proposed sensorless methods are based on the model reference adaptive system (MRAS) observer and adaptive speed observer (ASO). The proposed speed estimation algorithm can be employed in the power control of grid connected induction generator for wind power applications. Two proposed schemes are verified through computer simulation PSIM and compared their simulation results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.387-398
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• 2002

The impact response and damage of CLAS panel was investigated experimentally. The facesheet material used was RO4003 woven-glass hydrocarbon/ceramic and the core material was Nomex honeycomb with a cell size of 3.2mm and a density of 96 kg/㎥. The shield plane used was RO4003 and 2024-T3 aluminum. Static indentation and impact test was conducted to characterize the type and extent of the damage observed in two CLAS panels, and the performance of antenna used in a wireless LAN system. Correlation of peak contact force, residual indentation and the delamination area shows impact damage of the panel with an aluminum shield plane is larger than that of the panel with RO4003 shield plane, although the former is more penetration resistant. The damage was observed by naked eye, ultrasonic inspection and cross sectioning. The shape and size of delamination was estimated by ultrasonic inspection, and the area of delamination linearly increases as impact energy increases. The performance of impact damaged antenna was estimated by measuring return loss and radiation pattern. It was revealed that the performance of antenna was related to the impact damage and there was a threshold that the performance of antenna fell as impact energy level changed. The threshold was between the impact energies of 1.5J and 1.75J.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.3
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• pp.404-416
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• 2015

Small-area, low-power coarse and fine frequency detectors (FDs) are proposed for an adaptive bandwidth referenceless CDR with a wide range of input data rate. The coarse FD implemented with two flip-flops eliminates harmonic locking as long as the initial frequency of the CDR is lower than the target frequency. The fine FD samples the incoming input data by using half-rate four phase clocks, while the conventional rotational FD samples the full-rate clock signal by the incoming input data. The fine FD uses only a half number of flip-flops compared to the rotational FD by sharing the sampling and retiming circuitry with PLL. The proposed CDR chip in a 65-nm CMOS process satisfies the jitter tolerance specifications of both USB 3.0 and USB 3.1. The proposed CDR works in the range of input data rate; 2 Gb/s ~ 8 Gb/s at 1.2 V, 4 Gb/s ~ 11 Gb/s at 1.5 V. It consumes 26 mW at 5 Gb/s and 1.2 V, and 41 mW at 10 Gb/s and 1.5 V. The measured phase noise was -97.76 dBc/Hz at the 1 MHz frequency offset from the center frequency of 2.5 GHz. The measured rms jitter was 5.0 ps at 5 Gb/s and 4.5 ps at 10 Gb/s.

• Economic and Environmental Geology
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• v.21 no.2
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• pp.117-129
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• 1988

The purpose of this study is to determine the stratigraphy of the volcanic rocks in the Chilpo-Weolpo area, the north of Pohang basin, based on field survey and lithological properties of the rocks. The volcanic pile(Chilpo tuff) overlies the Cretaceous sedimentary formation and is unconformably overlain by the Miocene Yeonil Group. The Chilpo tuff comprises a thick sequence(>200m) of pyroclastic flow deposits. Five members are distinguished, each representing separate flow units, comprising none(or weakly) to densely welded rhyolite tuff. The Chilpo tuff consists of, in ascending order, greenish weakly welded tuff, volcanic conglomerate, alternation of tuff breccias and fine tuffs, greenish none to densely welded tuff and red-brownish densely to weakly welded vitric tuff. This study revealed that the volcanic rocks in this area were formed by 4 volcanic stages. On the basis of K-Ar age($44.7{\pm}1.1\;Ma$) and lithologic data, geological age of the Chilpo tuff may be Eocene.

• Corrosion Science and Technology
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• v.4 no.6
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• pp.236-241
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• 2005

Hydrogen induced cracking (HIC) is one of the hydrogen degradation phenomena of linepipe steels caused by $H_2S$ gas in the crude oil or natural gas. However, NACE TM0284-96 standard HIC test method is hard to satisfy the steel requirements for sour service application since it uses more severe environmental conditions than actual conditions. Therefore, in order to use steels effectively, it is required to evaluate HIC resistance of steels in the practical range of environmental severity. In this study, HIC resistance of two high strength low alloy (HSLA) steels being used as line pipe steels was evaluated in various test solutions with different $H_2S$ pressures and pH values. The results showed that the key parameter affecting crack area ratio (CAR) is $H_2S$ partial pressure of test solution when the pH value of test solution is not over 4. Hydrogen diffusivity was not a constant value, but it was rather affected by the hydrogen ion concentration (pH value) in the solution.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.155-167
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• 2015

An adaptive equalization scheme based on all-digital jitter measurement is proposed for a continuous time linear equalizer (CTLE) preceding a clock and data recovery (CDR) in a receiver circuit for high-speed serial interface. The optimum equalization coefficient of CTLE is determined during the initial training period based on the measured jitter. The proposed circuit finds automatically the optimum equalization coefficient for CTLE with 20", 30", 40" FR4 channel at the data rate of 5 Gbps. The chip area of the equalizer including the adaptive controller is 0.14 mm2 in a $0.13{\mu}m$ process. The equalizer consumes 12 mW at 1.2 V supply during the normal operation. The adaptive equalizer has been applied to a USB3.0 receiver.

• Geotechnical Engineering
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• v.14 no.5
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• pp.77-88
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• 1998

This study discusses the engineering characteristics and distribution of marine clay in Pohang by providing evidence that Pohang area has been upheaving in connection with the changes of sea level and geographical development in the Babt Coast. It is estimated that the sea level of the East Coast about 10,000 years ago had been 25 meters below than that of the present. The corroborative fact is that the marine clay deposited below the sea level due to the changes of the crust in Pohang is usually found above the sea level. Judging from their OCR values of leas than 0.77 and Bu/po'ratio of less than 0.14 at the depth of 7.8 meters below the ground level, marine clays of Dohu 1-dong and Jangsung-dong in Pohang City are presumed to be in a state of underconsolidation. However, more sophisticated measures and analysis are needed to prove it.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.3
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• pp.3-10
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• 2019

On November 15, 2017, an earthquake($M_L5.4$) occurred in Pohang. Pohang earthquake was the second largest earthquake since earthquake was observed in Korea, but structural damage caused by earthquake was biggest. Structural damage caused by Pohang earthquake was mainly caused by schools and pilotis, above all damage to pilotis was outstanding. This is because area where pilotis structures are concentrated is located near epicenter, and seismic performance of pilotis structures is not excellent compared with general structures. In this study, described results of damage investigation and analysis of damage causes through analysis of pilotis Structures on 131 buildings that were investigated immediately after Pohang earthquake. In addition, cause of damage was analyzed through analysis of seismic wave. Investigation site was selected to Jangseong-dong, where damage occurred in large numbers. Damage level was classified into A, B, and C level by measuring residual crack width and story drift of structural members.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2001.06a
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• pp.116-119
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• 2001