• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1558-1563
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• 2007

In this paper, phase-locked loop (PLL) of a combinational architecture consisting of an adaptive bandwidth and fractional-N is presented to improve performances and reduce the order of ${\Delta}{\Sigma}$ modulator while maintaining equivalent or better performance with fast locking. The architecture of adaptive bandwidth PLL was simulated by HSPICE using 0.35m CMOS parameters. The behavioral simulation of the proposed adaptive bandwidth fractional-N PLL with a ${\Delta}{\Sigma}$ modulator was carried out by using MatLab to determine if the architecture could achieve the objectives. The HSPICE simulation showed that this type of PLL was able to fast locking, and reduce fractional spurs about 20dB.

• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.546-548
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• 1993

The discrete structure of substituted 9-benzonorbornenyl cation 3a and 3c was studied using the empirical ${\Delta}$J equation which was developed by Kelly and coworker$^5$. The ${\Delta}$J values of substituted 9-benzonorbornenyl cations were obtained from p-methyl-6,7-dimethyl benzonorbornen-9-yl (3a) and 9-methyl-6,7-dimethyl benzonorbonen-9-yl (3c) cations under stable ion conditions, and were compared with those of the corresponding ketone analog; these cations were generated by dissolving the corresponding carbinols in superacid at -120$^{\circ}$C and the nmr spectra taken at -60$^{\circ}$C~-90$^{\circ}$C. The ${\Delta}$J values are 8.7 Hz for the bridgehead carbons in cation 3c and 3.1 Hz for cation 3b. The ${\Delta}$J values at C5,8 in fused benzene ring are 14.3 Hz for cation 3c and 8.7 Hz for cation 3a. The excellent correlation of the ${\Delta}$J values with 1$^9F$ chemical shifts of p-fluorophenyl-6,7-dimethylbenzonorbornenyl cation (3d) indicate that ${\Delta}$J value is a reliable probe to charge density at adjacent cationic carbon. These NMR parameters strongly support that the symmetrically ${\pi}$-bridged nonclassical structure (type 2) of substituted 9-benzonorbornenyl cations in stable ion conditions.

• Journal of the Korean earth science society
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• v.37 no.7
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• pp.389-397
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• 2016

In order to investigate the light curve difference in visual and infrared wavelength of ${\delta}$ Scuti variable Bo Lyn, observations were performed using BOAO 1.8m reflecting telescope and an infrared detector, KASINICS, with J, H, and Ks filters. Infrared light curves of total 7 nights were obtained between March and April in 2011, and those were compared to the V-filter light curve to examine the differences in period, time of maximum light, amplitude, and shape. From the periodic analysis of infrared light curve, a single frequency of $f_1=10.712cycle/day$, $P=0.09335{\pm}0.00002days$ was obtained, and there was no difference in the period along different wavelengths. In the infrared light curve, a frequency of $2f_1$ was detected. This frequency well explains the asymmetric shape of light curve, one of the characteristics of high-amplitude ${\delta}$ Scuti variables. We compared the locations of the measured infrared maxima and the predicted maxima of V-filter, finding that the times of maxima were delayed about 0.3 phase at infrared wavelengths. Amplitude ratios were adopted to be ${\Delta}J/{\Delta}V=0.328$, ${\Delta}H/{\Delta}V=0.216$, and ${\Delta}Ks/{\Delta}V=0.211$, with the range of variation being smaller at longer wavelengths. It seems that the differences in the times of maxima and amplitude occurred because the changes in brightness of a pulsating variable star are mainly caused by the change in temperature.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.345-357
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• 2005

Prostaglandin plays a significant role in the local control of bone metabolism associated with periodontal disease. ${\Delta}^{12}-PGJ_2$ is a natural $PGD_2$ metabolite that is formed in vivo in the presence of plasma. It is known for ${\Delta}^{12}-PGJ_2$ to stimulate calcification in osteoblastic cells. Bone morphogenetic protein(BMP) stimulated osteoblastic differentiation in various types of cells and greatly enhanced healing of bony defects. The purpose of this study was to evaluate the effect of rhEMP-2 on ${\Delta}^{12}-PGJ_2$ induced osteoblastic differentiation and mineralization in vitro. A human osteosarcoma cells line Saos-2 were cultured. In the test groups, 10-7M of ${\Delta}^{12}-PGJ_2$ or mixture of 10-8M of ${\Delta}^{12}-PGJ_2$ and 100ng/ml of rhBMP-2 or 100ng/ml of rhEMP-2 were added to culture media. After 1 day, 2 days and 4 days of culture period, the cell number was measured. Alkaline phosphatase activity was measure at 3 days. Reverse transcription polymerase chain reaction(RT-PCR) was performed to determine the expression of mRNA of bone matrix protein at 8 hours, 1 day and 7 days. The ability to produce mineralized nodules in rat osteoblasts(MC3T3-E1) was evaluated at 21 days. The results were as follows : 1. rhEMP-2 or mixture of rhBMP-2 and ${\Delta}^{12}-PGJ_2$ inhibited cell proliferation of human osteosarcoma cells. 2. rhEMP-2 or mixture of rhBMP-2 and ${\Delta}^{12}-PGJ_2$ stimulated alkaline phosphatase activity significantly higher than ${\Delta}^{12}-PGJ_2$ alone. 3. rhBMP-2 or mixture of rhEMP-2 and ${\Delta}^{12}-PGJ_2$ stimulated mineralization compared to ${\Delta}^{12}-PGJ_2$ alone. 4. mRNA of alkaline phosphatase, BMP-2, cbfa 1, Type I collagen were detected in the group treated with ${\Delta}^{12}-PGJ_2$/rhBMP-2, rhBMP-2 alone, ${\Delta}^{12}-PGJ_2$ alone. These results show that mixture of ${\Delta}^{12}-PGJ_2$ and rhBMP-2 causes more bone formation than ${\Delta}^{12}-PGJ_2$ alone while the bone formation effects of mixture of ${\Delta}^{12}-PGJ_2$ and rhBMP-2 are less than those of rhBMP-2 alone. Further researches would be necessary to clarify the interactions of these agents.

• Economic and Environmental Geology
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• v.30 no.1
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• pp.25-33
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• 1997

The purpose of this study is to examine the feasibility of using stable isotopes as a hydrologic tracer, and to elucidate the groundwater circulation system and the source of S component dissolved in thermal water of the Chonju Jukrim thermal spring district based on the O, H and S isotopic variabilities of environmental materials including bedrock, rainwater, surface water, shallow subsurface water and thermal spring water. The ${\delta}^{18}O$ and ${\delta}D$ of subsurface waters and surface water show highly restricted range and plotted on the same meteoric water line as a ${\delta}D=8{\delta}^{18}O+19$ line, and derivate from the mean annual isotopic composition of the rain water but are analogous to those of rain waters precipitated during winter season, indicating that ground waters are originated from the meteoric water and are strongly affected by the seasonal variation of air mass. Thermal spring waters are more depleted in ${\delta}^{18}O$ and ${\delta}D$ than those of shallow ground water and surface water. It can be explained by the difference of recharge area. The hydrochemical properties of subsurface waters and surface water devide into two groups: $Ca(HCO_3)_2$ type including shallow subsurface water and surface water, and $Na(HCO_3)$ type of thermal spring waters. The ${\delta}^{34}S$ values of thermal spring water show very high positive and quitely distinct from those of shallow subsurface water and surface water that are similar to those of bed rocks, indicating that sulfate dissolved in thermal spring water has not only a terrigenic origin, but also originates partially from the foreign source containing very heavy ${\delta}^{34}S$ component such as an ancient sea water. However, the presence of $H_2S$ can not be ignore the affact of the isotopic fractionation to explaine the heavy ${\delta}^{34}S$ of thermal spring water. Overall, the Oxygen and Hydrogen stable isotopes can identify the source and the circulation system of the natural waters and the S-isotopes can provide a crucial clue on tracing the dissolved material transports in the circulation system of the natural water.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.16-20
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• 1988

This paper presents a new algorithm for solving the inverse kinematics in real-time applications. The end-tip movement of each link can be resolved into the basic resolution unit, .DELTA.l, which depends on link length, reduction ratio and resolution of the incremental encoder attached to the joint. When x- and y-axis projection of the end-tip movement are expressed in .DELTA.l unit, projectional increments .DELTA.x and .DELTA.y become -1, 0 or I by truncation. By using the incremental computation with these ternary value and some simple logic rules, a coordinate transformation can be realized. Through this approach, it should be noted that the floating-point arithmetic and the manipulation of trigonometric functions are completely eliminated. This paper demonstrates the proposed method in a parallelogram linkage type, two-link arm.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.3
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• pp.244-252
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• 1992

This paper describes a reactive power compensator using current-source delta modulation converter, which compensates the reactive power in the ac sides of 3-phase rectifier. In the conventional current control methods for the current-type reactive power compensators, it is usual to compare the reactive reference current signal with the triangular wave and hence to generate the ON-OFF signals for the reactive power compensator. To improve the response as well as the control capability, the delta modulated current control technique is used in this paper. As a result, the input power factor is improved close to unity and both simulation and experimental results show good compensating performances.

• Publications of The Korean Astronomical Society
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• v.24 no.1
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• pp.9-18
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• 2009

From the short-period variability survey (SPVS) in Bohyunsan Optical Astronomy Observatory, we obtained time-series BV CCD images in the region of an open cluster M38 (NGC 1912) for 23 nights from February 1, 2007 to December 7, 2008. We found 18 $\delta$ Scuti stars and 2 $\gamma$ Doradus stars. Among them, only 3 $\delta$ Scuti stars were known ones. From the color-magnitude diagram (CMD) of M38, most of them have been located in the instability strip. The two $\gamma$ Doradus stars have been located within $\gamma$ Doradus strip of M38. But, only four $\delta$ Scuti stars were located within radius 10' from the center of M38. To confirm of their membership for M38, we need more study, such as, proper motion by spectroscopic observation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.545-550
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• 2007

Due to many advantages such as lightweight, high durability and speedy construction, increasing number of bridges of various girder types are being built recently with glass-fiber reinforced composite deck. A profile of the composite deck, called 'Delta deck', is developed which has 3 trapezoidal cells of 200mm depth. This paper introduces how to develop 'Delta deck' and its application to the world largest composite-deck bridge, which is 300m long and 35m wide and is currently under construction.

• Journal of Astronomy and Space Sciences
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• v.6 no.1
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• pp.41-47
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• 1989

UBV photoelectric observations of RS CVn type variable star HD 8358 were made using the 61cm reflector at Sobaeksan Astronomical Observatory. The data were obtained on 15 nights from October 1987 to December 1988. Double peaks of maximum light is seen from the light curve and continuous change of phase in notified from the times of maximum lights. The colors of October, 1987 - January, 1988 observations are bluer in $\Delta(b-\upsilon)$, but redder in $\Delta(\upsilon$-b), than those of November -December, 1988 observations.