• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.373-376
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• 2004

A novel Er(III) complex with oxydiacetate and 1,10-phenanthroline was synthesized and its structure and luminescence properties were characterized. The complex of $[Er(ODA){\cdot}(phen){\cdot}4H_2O]^+$ crystallizes in the monoclinic space group $P2_1$/n with a = 12.216(4) ${\AA}$, b = 16.680(2) ${\AA}$, c = 12.627(3) ${\AA}$, ${\beta}=108.30(2)^{\circ}$, V = 2442.7(11) ${\AA}^3$, Z = 4 and ${\rho}=1.841 g/cm^3$. When the complex is excited at the He-Cd 325-nm line, it produces two broad bands spanning the regions 350-650 nm and 1200-1650 nm. The emission band of the complex is characterized by a series of spectral dips in the visible emission profile. The complex exhibits sensitized near- IR emission via two kinds of energy transfers from phen to Er(III): nonradiative and radiative energy transfers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.363-369
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• 2004

We propose, for the first time to our knowledge, a novel gain-clamping method for EDFA in WDM add/drop networks by introducing a disturbance observer technique. The control input signal for gain-clamping is composed of a nominal control signal and an additional control signal of compensating the gain fluctuations caused by channel add/drops. Based on disturbance observer technique, we designed the additional control signal such that it has the compensating information of estimated disturbance resulted from channel add/drops. The circuit for generating additional control signal can easily be implemented by using simple electronic devices. We proved the superiority of the new technique over the previous ones by showing simulation results of minimized dips and spikes that appear in power profile of EDFA in the process of channel add/drops.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1056-1058
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• 1998

Voltage dips caused by transmission system faults are usually of a short duration. High speed relaying and breaker operation will typically limit the disturbance to 0.1 seconds. Most motor controllers obtain their control power directly from the bus by means of a control transformer. Under this condition, a voltage dip can cause the contactor to drop out. disconnecting the motor from the line. The rapid re-energizing of the controller is in effect a fast reclosure which may result in motor damage. The time delay re-energizing of controller will result in a greater loss of speed and possibly loss of stability. Other means of controller can be used to prevent the motor from being disconnected from line during the fault. This can be accomplished by DC power controller or mechanically latched controller. This paper demonstrates that DC power controller or mechanically latched type controller to prevent the motor from being disconnected from line during the fault is, the most effective in minimizing speed reduction, transient motor current, transient motor torque and transient shaft torque by EMTP calculation.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.1-11
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• 1998

A line profile synthesis method is presented that minimizes the nearest-neighbor crosstalk peak level for high-speed pulse transmission in multi-coupled microstrip signal buses. We adopted the optimization technique for the reflected wave control on bus lines resulting in increasing the average spacing between strip conductors, since in a parallel-conductor bus the crosstalk energy is concentrated at the nearest neighbors of the driven line. The generalized S-matrix technique is applied for the input and output waveform prediction, and crosstalk characteristics of various nonuniform lines synthesized for increasing the average spacing are analyzed by comparing each other. Simulation results demonstrate that the Chebyshev taper with dips is adequate to significantly minimize the crosstalk peak level under the satisfactory waveform integrity since the profile is oriented to evenly reflect significant pulse spectra within the frequency range of pulse.

• Journal of Magnetics
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• v.14 no.1
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• pp.11-14
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• 2009

We investigated the I-V curves and differential tunneling conductance of two, CoFeB/MgO/CoFeB-based, magnetic tunnel junctions (MTJs): one with a low tunneling magnetoresistance (TMR; 22%) and the other with a high TMR (352%). This huge TMR difference was achieved by different MgO sputter conditions rather than by different annealing or deposition temperature. In addition to the TMR difference, the junction resistances were much higher in the low-TMR MTJ than in the high-TMR MTJ. The low-TMR MTJ showed a clear parabolic behavior in the dI/dV-V curve. This high resistance and parabolic behavior were well explained by the Simmons' simple barrier model. However, the tunneling properties of the high-TMR MTJ could not be explained by this model. The characteristic tunneling properties of the high-TMR MTJ were a relatively low junction resistance, a linear relation in the I-V curve, and conduction dips in the differential tunneling conductance. We explained these features by applying the coherent tunneling model.

• Geomechanics and Engineering
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• v.17 no.3
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• pp.279-285
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• 2019

The process of slope stability analysis is one of the most important stages in design of some civil and mining projects. Bimslopes are made from bimrocks (block-in-matrix rocks) where rocky blocks are distributed in a bonded matrix of finer texture. These kind of slopes are often seen in weathered and near-surface depths. Previous studies have shown that VBP (Volumetric Block Proportion) is one of the most significant factors affecting bimrocks strength and consequently the stability of bimslopes. In this paper, the influence of block inclinations on bimslope stability have been investigated. For this purpose, 180 theoretical models have been made with various VBPs, all of them have a specified block size distribution. These bimslopes contain blocks with differing dips relative the slope inclination. Also for each kind of block inclination, 10 different blocks arrangements have been modeled. The Finite Element Method (FEM) was used to analysis the stability of these bimslopes models. The results showed the inclination of blocks has a strong impact on the Safety Factor and stability of bimslopes. When the difference in angle of dip of blocks relative to the slope angle is maximum, the Safety Factor of bimslopes tends to be a maximum compared with the matrix-only state. Furthermore, with increasing VBP of bimslopes stability increases. The graphs obtained from this study could be used for preliminary guidance in the projects design with bimslopes.

• Economic and Environmental Geology
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• v.2 no.4
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• pp.1-21
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• 1969

The Sin po fluorite deposit is of a fissure vein type which strikes $N75^{\circ}E$, dips $80^{\circ}SE$, and is embedded in the pre-Cambrian crystalline schist. The vein is 1 meter in average in thickness, about 800 meters in length and nearly 400 meters in depth. Narrow veins of crustified fluorites and agatic quartz are discontinuously embedded in the quartz gangue. Two-phase fluid inclusions, which are available for the homogenization method by using the Heating Stage Microscope 350, are found in the fluorite crystals. Most of the fluid inclusions are primary in origin and mainly composed of liquid phase associated with minor gas phase. They are tetrahedral, rounded-tubular, wedge shaped, rectangulartrapezoid, and irregular in shape. The maximum diameter of inclusions is 0.5mm and the minimum, 0.03mm, ranging from 0.2mm to 0.08mm in an average. The homogenization temperatures obtained from the test are $135-147^{\circ}C$, $125-138^{\circ}C$, $121-137^{\circ}C$, $116-133^{\circ}C$ and $106-128^{\circ}C$ in greenish, bluish, violet, light grayish blue, colorless and pinkish fluorites respectively. The range of formation temperatures of fluorites is $106-147^{\circ}C$. Therefore, the fluorite deposit of Sinpo Mine is considered to be of low temperature hydrothermal origin. The isothermal lines were drawn on the longitudinal section of the vein from the data of homogenization test. According to the results, the central and lower parts of the ore shoot in the west ore body show the higher temperatures of $130-138^{\circ}C$ and the peripheral and upper parts of it show the lower temperatures of $108-128^{\circ}C$. It seems that the isothermal trend roughly coinside with the pitch of the ore shoot.

• The Journal of Engineering Geology
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• v.16 no.1 s.47
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• pp.23-30
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• 2006

This study was carried out to understand the relationship between orientation of tecto-lineaments obtained from aero-photograph and orientation of discontinuities measured at field for the rock types of igneous, sedimentary and metamorphic rocks in Andong area. Total 847 tecto-lineaments were extracted from the aero-photographs and total 1,940 discontinuities including joints, foliations and faults were measured during geologic survey. By using the software DIPS, preferred trends of tecto-lineaments were deduced as N30E-N40E for igneous rocks and N50E-N60E for both sedimentary and metamorphic rocks, while the trends of discontinuities were found as N40E-N50E for igneous rocks, N50E-N80E for sedimentary rocks and N50E-N60E for meta morphic rocks. Even though both orientations for a given rock type showed relatively good agreement in its trend, some discrepancy is also appeared. Since construction safety of geo-structures such as tunnel and slope, etc., is significantly affected by the orientation of discontinuities in rock masses, it is highly recommended to perform a detailed geologic survey as well as an aero-photograph interpretation at a design stage.

• The Journal of Engineering Geology
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• v.13 no.2
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• pp.193-205
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• 2003

Fine grained granite, porphyritic granite and biotite granite together with intruded and extruded andesitic rocks are distributed in the study area which is bounded by the Yangsan and Dongrae faults. A new domestic road is being constructed along the area between the two major faults. The NNE trending Bupki fault and NE trending Myungkog fault are also developed within the area cross the road. The sheeting joints with dips of less than 30 degrees are only developed in the area of granite outcrop. High angle joints can be divided into 3 sets, such as, NE trending, NW trending and nearly EW trending joints. The joint space is mostly more than 20cm and the joint compressive strength is more than 100 MPa. These data show that even though the study area is situated between large faults, the ground condition is good because the damage zone of the Yangsan and Dongrae faults is relatively narrow.

• Economic and Environmental Geology
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• v.3 no.3
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• pp.169-176
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• 1970

Kubong Gold Mine is located in Kuryongri, Sayang-myun, Chungyang-gun, Choongchung-Namdo.(latitude $36^{\circ}24^{\prime}N$. longitude $126^{\circ}45^{\prime}30^{{\prime}{\prime}}E$) The mine was begun to work soon after the inhabitants of this village had accidently discovered the outcrops in April 1908. It is one of the largest gold mines in Korea which produces 4,500 tons of crude ore a month. The geology in the area consists of granitic gneiss, banded gneiss, augen-gneiss, mica schist, limesilicate of Pre-Cambrian series and sedimentary rocks(sandstones & conglomerates) of Daedong series. Basic dikes intrude the former formations. The country rock of the ore deposit is a group of the metamorphic rocks mentioned above. Gold-silver bearing quartz vein contains small amounts of pyrite, chalcopyrite, arsenopyrite, galena and sphalerite in which gold and silver occur as native state. The vein strikes $N30^{\circ}{\sim}60^{\circ}E$ and dips $20^{\circ}{\sim}50^{\circ}S$ and the average width of the vein is estimated 1 to 1.5m. Average grade of ore is Au:6~8gr/t and Ag:5~6gr/t. The ore shoot continues from the outcrop to the depth of -1760ML with dip of $20{\sim}25^{\circ}$ and strike extension reaches to 400m at the depth of -1440 ML and to more or less 200m at below. Highgrade of ore vein was found at the lowest level of the ore shoot at the time of recent field survey at the end of August 1970. Its average grade was estimated as Au:20gr/t and its width 1~2.5M in average. A series of futher prospecting for other new ore shoot or parallel veins are urgent and crosscut prospecting along the horizontal level is strongly recommended.