• Journal of Magnetics
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• v.6 no.3
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• pp.86-89
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• 2001

Microstructure modifications are investigated for annealed Co-based amorphous ribbon in vacuum and open air. X-ray diffraction (XRD) spectra for annealed sample in vacuum indicate atomic arrangements with initial nucleation of hcp-Co crystallite at 38$0^{\circ}C$ annealing temperature. However, the XRD spectra in samples with long annealing times of $t_a\geq300$ min demonstrate sharp and good developed surface crystalline hcp-, fcc- Co and $Co_2$Si phases. The giant magnetoimpedance (GMI) profile at 0.1 MHz displaying one-peak behavior in vacuum annealed samples at T = 38$0^{\circ}C$ irrespective of annealing time $t_a$ from 20 to 480 mim. For the annealed samples in an open air, the GMI profile shows two-peaks for $t_a$ = 20 min annealed sample. However, one of peaks disappears and an asymmetric GMI profile exhibits a drastic step-like change near zero field for $t_a\geq300$min. Such asymmetric GMI characteristics is related to the surface microstructures of fcc-Co, hop-Co and $Co_2$Si crystalline phases.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.179-200
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• 1996

The intrinsic instabilities of fluid flow occurred in the melt of the Czochralski crystal growth system Czochralski method, asymmetric flow patterns and temperature profiles in the melt have been studied by many researchers. The idea that the non-symmetric structure of the growing equipment is responsible for the asymmetric profiles is usually accepted at the first time. However further researches revealed that some intrinsic instabilities not related to the non-symmetric equipment structure in the melt could also appear. Ristorcelli had pointed out that there are many possible causes of instabilities in the melt. The instabilities appears because of the coupling effects of fluid flow and temperature profiles in the melt. Among the instabilities, the B nard type instabilities with no or low crucible rotation rates are analyzed by the visualizing experiments using X-ray radiography and the 3-D numerical simulation in this study. The velocity profiles in the Silicon melt at different crucible rotation rates were measured using X-ray radiography method using tungsten tracers in the melt. The results showed that there exits two types of fluid flow mode. One is axisymmetric flow, the other is asymmetric flow. In the axisymmetric flow, the trajectory of the tracers show torus pattern. However, more exact measurement of the axisymmetrc case shows that this flow field has small non-axisymmetric components of the velocity. When fluid flow is asymmetric, the tracers show random motion from the fixed view point. On the other hand, when the observer rotates to the same velocity of the crucible, the trajectory of the tracer show a rotating motion, the center of the motion is not same the center of the melt. The temperature of a point in the melt were measured using thermocouples with different rotating rates. Measured temperatures oscillated. Such kind of oscillations are also measured by the other researchers. The behavior of temperature oscillations were quite different between at low rotations and at high rotations. Above experimental results means that the fluid flow and temperature profiles in the melt is not symmetric, and then the mode of the asymmetric is changed when rotation rates are changed. To compare with these experimental results, the fluid flow and temperature profiles at no rotation and 8 rpm of crucible rotation rates on the same size of crucible is calculated using a 3-dimensional numerical simulation. A finite different method is adopted for this simulation. 50×30×30 grids are used. The numerical simulation also showed that the velocity and flow profiles are changed when rotation rates change. Futhermore, the flow patterns and temperature profiles of both cases are not axisymmetric even though axisymmetric boundary conditions are used. Several cells appear at no rotation. The cells are formed by the unstable vertical temperature profiles (upper region is colder than lower part) beneath the free surface of the melt. When the temperature profile is combined with density difference (Rayleigh-B nard instability) or surface tension difference (Marangoni-B nard instability) on temperature, cell structures are naturally formed. Both sources of instabilities are coupled to the cell structures in the melt of the Czochralski process. With high rotation rates, the shape of the fluid field is changed to another type of asymmetric profile. Because of the velocity profile, isothermal lines on the plane vertical to the centerline change to elliptic. When the velocity profiles are plotted at the rotating view point, two vortices appear at the both sides of centerline. These vortices seem to be the main reason of the tracer behavior shown in the asymmetric velocity experiment. This profile is quite similar to the profiles created by the baroclinic instability on the rotating annulus. The temperature profiles obtained from the numerical calculations and Fourier transforms of it are quite similar to the results of the experiment. bove esults intend that at least two types of intrinsic instabilities can occur in the melt of Czochralski growing systems. Because the instabilities cause temperature fluctuations in the melt and near the crystal-melt interface, some defects may be generated by them. When the crucible size becomes large, the intensity of the instabilities should increase. Therefore, to produce large single crystals with good quality, the behavior of the intrinsic instabilities in the melt as well as the effects of the instabilities on the defects in the ingot should be studied. As one of the cause of the defects in the large diameter Silicon single crystal grown by the

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.383-386
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• 2006

Subsurface temperature is affected by heat advection due to groundwater advection. Temperature-depth profile can be perturbed especially when there are significant vertical groundwater flux caused by external force such as injection or extraction. This research is to clarify the change of subsurface temperature distribution when the 40m x l0m sandy aquifer is stimulated by two different vertical flux($case1:\;{\pm}10^{-5}m^3/s,\;case2:\;{\pm}4{\times}10^{-5}m^3/s$) using a program called HydroGeoSphere. The resulting temperature distribution contour map shows pumping causes vertical attraction of water from deeper and warmer place which result in rising up isotherm. Additionally more injection/extraction rate, more vertical groundwater flux leads to faster Increase in temperature near the pumping well.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.93-98
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• 2008

We investigated the effect of process temperature on removal rate and non-uniformity based on single head kinematics in oxide CMP. Generally, it has been known that the temperature profile directly transfers to the non~uniformity of removal rate on the wafer, which has similar tendency with the sliding distance of wafer. Experimental results show that platen velocity is a dominant factor in removal rate as well as average temperature. However, the non-uniformity does not coincide between process temperature and removal rate, due to slurry accumulation and low deviation of temperature. Resultantly, the removal rate is strongly dependent on the rotational speed of platen, and its non -uniformity is controlled by the rotational speed of polishing head. It means lower WIWNU (With-in-wafer-non-uniformity) can be achieved in the region of higher head speed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.86-94
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• 2004

The flash temperature distribution on the contact surfaces between cam and roller-follower mechanism was analysed numerically. The elasto-hydrodynamic lubrication pressure and film thickness were used to get the accurate analysis results. The temperature distribution was obtained by numerical integration by making use of Carslaw and Jaeger's formulation to the whole contact surfaces. The maximum flash temperature was increased with both the increasing slip ratio of the contact surface and increasing external load Profile of the temperature distribution was affected by the sliding velocity of the surface.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.1
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• pp.1-10
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• 1988

The vertical temperature profiles of the Yellow Sea in summer are investigated by means of the nine air temperature (AT) patterns which are classified with the AT of winter and summer. The sea surface temperature (SST) is high when the AT of summer is high, and vice versa. The gradient of thermocline in the offshore region is higher than that in the coastal region and is not always favorable with the AT patterns. The relation between sea bottom temperature (SBT) and the AT of winter is favorable when the SBT is averaged in the coastal and offshore stations. In addition, the SST of coastal stations is higher than that of offshore stations because of the strong mixing by the tidal current in the coastal region. The correlation between the AT and the SST of August is favorable (r=0.44-0.69), while the correlation between the AT of February and the SBT of August is not favorable except the stations, A2 (r=0.57) and B2 (r=0.61).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.368-377
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• 2004

A mathematical model was developed for the prediction of the average temperature and RDT(RM Delivery temperature) in a roughing mill. The model consisted of three parts as follows (1) The intermediate numerical model calculated the deformation and heat transfer phenomena in the rolling: region by steady state FEM and the heat transfer phenomena in the interpass region by unsteady state FEM (2) The Off-line prediction model was derived from non-linear regression analysis based on the results of intermediate numerical model considering the various rolling conditions, (3) Using the heat flux in rolling region, temperature profile along thickness direction was calculated. For validation of the presented model, the rolling force per pass and RDT measued in on-line process was compared with those of model and the results showed close agreement with the existing data. In order to demonstrate the effectiveness of the proposed model, the various rolling conditions was tested.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1989.10a
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• pp.13-18
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• 1989

Temperature distribution of 250W high-pressure mercury lamp has been measured by the spectroscopic method using relative intensities of spectral lines. To obtain radial temperature distribution, the measured intensity which was integrated along the line of sight was transformed into radial line intensity by Abel's inversion. Temperature was determined from relative intensities of spectral lines of the same atomic species. The measured temperature of 250W high-pressure mercury lamp is 6000K at the axis. In this experiment temperature profile of high-pressure arc is papabolic as known.

• Journal of Environmental Impact Assessment
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• v.20 no.4
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• pp.435-442
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• 2011

In this study, a regression model was developed for prediction of inflow temperature to support an effective thermal stratification simulation of Yongdam Reservoir, using the relationship between gaged inflow temperature and air temperature. The effect of reproductability for thermal stratification was evaluated using EFDC model by gaged vertical profile data of water temperature(from June to December in 2005) and ex-developed regression models. Therefore, in the development process, the coefficient of correlation and determination are 0.96 and 0.922, respectively. Moreover, the developed model showed good performance in reproducing the reservoir thermal stratification. Results of this research can be a role to provide a base for building of prediction model for water quality management in near future.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.206-208
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• 2000

0.65 mol% MgO-doped LiNbO$_3$single crystals were grown by CZ method. The obtained single crystals were colorless and transparent. Noncritically phase-matched second harmonic generation (SHG) of 532-nm radiation from 1064-nm in MgO-doped LiNbO$_3$has been investigated by using pulsed Nd:YAG laser. The phase-matching temperature was room temperature. SHG conversion efficiencies were typically achieved higher than 50% at the phase-matching temperature with no photorefractive damage in the region of fundamental power density which was used in this experiment. The thermo-birefringence coefficient and the electro-birefringence coefficient of SHG were calculated from the temperature phase-matching profile with the electric field.