• Communications of the Korean Mathematical Society
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• v.18 no.1
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• pp.105-115
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• 2003

It is well known that there exists a regular branched covering map from T$^2$ onto $\={C}$ iff the ramification indices are (2,2,2,2), (2,4,4), (2,3,6) and (3,3,3). In this paper we construct (count-ably many) chaotic homeomorphisms induced by hyperbolic toral automorphism and regular branched covering map corresponding to the ramification indices (2,2,2,2). And we also gave an example which shows that the above construction of a chaotic map is not true in general if the ramification indices is (2,4,4) and also show that there are no chaotic homeomorphisms induced by hyperbolic toral automorphism and regular branched covering map corresponding to the ramification indices (2,3,6) and (3,3,3).

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.67-72
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• 1998

The mapping of the spin-spin relaxation time T2 in pixel-by-pixel was suggested as a quantitative diagnostic tool in medicine. although the CPMG pulse sequence has been known to be the best pulse sequence for T2 measurement in physics NMR, the supplied pulse sequence by the manufacture of MRI system was able to obtain the maximum of 4 CPMG images. Eight or more images with different echo time TEs are required to construct a reliable T2 map, so that two or more acquisitions were required, which easily took more than 10 minutes. 4-echo CPMG imaging pulse sequence was modified to generate the maximum of 8 MR images with evenly spaced echo time TEs. In human MR imaging, since patients tend to move at least several pixels between the different acquisitions, 8-echo CPMG imaging sequence reduces the acquisition time and may remove any mis-regitration of each pixels signal for the fitting of T2. The resultant T2 maps using the theoretically simulated images and using the MR images of the human brain suggested that 8 echo CPMG sequence with short echo spacing such as 17-20 msec can give the reliable T2 map.

• Journal of Animal Science and Technology
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• v.52 no.6
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• pp.513-519
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• 2010

A series of experiments were performed to study the influence of the following parameters on the physical traits and composition of swine manure compost: (1) addition of magnesium (Mg) at a molar ratio of 1.2 with respect to $PO_4$, and (2) reutilization of compost containing $MgNH_4PO_4{\cdot}6H_2O$ (magnesium ammonium phosphate, MAP). Three independent batch tests were conducted for replication: batch test I-control (C) and Mg added (T), batch test II-C, T and compost recycle ($T_{R1}$), and batch test III-C, T and compost recycle ($T_{R2}$). Magnesium addition and compost reutilization had no adverse effect on the degradation of organic matter. Reuse of the compost, however, had a clear effect on the total nitrogen (TN) and total phosphorus (TP) contents in the final compost. Repeated compost reutilization as a bulking material was resulted in composts rich in N and P. Upon adding the Mg supplement to the composting materials, the ortho-phosphate (OP) to TP ratio decreased due to the MAP crystallization reaction. The decrease in the OP/TP ratio and the increase in the TP content of the compost indicate that water-soluble phosphate is converted into a slow-release phosphate by the formation of crystals during composting. X-ray diffraction analysis of the irregular shaped crystals in the compost indicated that they are MAP crystals and that the crystallization of MAP begins immediately after the addition of the Mg supplement. The Mg addition to composting materials and the reutilization of compost as a bulking material would be a practical means to conserve nutrient content.

• Animal cells and systems
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• v.10 no.2
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• pp.79-83
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• 2006

Tissue plasminogen activator (tPA) is used to lyse clots and reperfuse brain in ischemic stroke. However, sideeffects of intracerebral hemorrhage (ICH) and edema limit their clinical application. In part, these phenomena has been linked with elevations in matrix metalloproteinase-9 (MMP-9) in neurovascular unit. However little is known about their regulatory signaling pathways in brain cells. Here, I examine the role of MAP kinase pathways in tPA-induced MMP-9 regulation in rat cortical astrocytes. tPA $(1-10\;{\mu}g/ml)$ induced dose-dependent elevations in MMP-9 and MMP-2 in conditioned media. Although tPA increased phosphorylation in two MAP kinases (ERK, JNK), only inhibition of the JNK pathway by the JNK inhibitor SP600126 significantly reduced MMP-9 upregulation. Neither ERK inhibition with U0126 nor p38 inhibition with SB203580 had any significant effects. Taken together, these results suggest that c-jun N-terminal kinase (JNK) plays an essential role for tPA-induced MMP-9 upregulation.

• The Journal of Natural Sciences
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• v.7
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• pp.5-9
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• 1995

We have controlled the chaotic output of Lorenz equation by using a return map. By applying small perturbations, the chaotic temporal behaviors and phase diagrams have been stabilized to period-1T, -2T, -3T which are unstable fixed points respectively as the same behaviors as the OGY method.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.3
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• pp.13-26
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• 2018

This study estimated the carbon sequestration from urban green spaces in Ansan City using environmental spatial information. We examined study results of carbon sequestration from existing urban green spaces, using a land cover map (level 3). In particular, the carbon sequestration of trees by land use and the IPCC Global default value were linked with the land cover map level 3. Domestic research showed that carbon storage in urban green spaces in Ansan City was 17,927.2 tC, and the annual carbon sequestration was calculated as 2,680.5 tC/yr. On the other hand, applying the IPCC Global Default value resulted in annual carbon sequestration of 5,287.8 tC/yr, which was 2,607.3 tC/yr more that the domestic research value. This resulted from difference in detailed methodologies such as background data, sample size for on-site investigation, and measurement of tree species. The study presented a consistent assessment method to assess the sequestration of carbon from municipal urban green spaces. Furthermore, we provided basic data that could be useful in urban green space policies.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.40.2-40.2
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• 2018

NGC 5024 and NGC 5053 are among the most metal-poor globular clusters in the Milky Way. Both globular clusters are considered to be accreted from dwarf galaxies (like Sagittarius dwarf galaxy or Magellanic clouds), and common stellar envelope and tidal tails between globular clusters are also detected. We present a search for extra-tidal cluster member candidates around these globular clusters from APOGEE survey data. Using 20 chemical elements (e.g., Fe, C, Mg, Al) and radial velocities, t-distributed stochastic neighbour embedding (t-SNE), which identifies an optimal mapping of a high-dimensional space into fewer dimensions, was explored, and we find that globular cluster stars are well separated from the field stars in 2-dimensional map from t-SNE. We also find that some stars selected in t-SNE map are placed outside of the tidal radius of the clusters. The proper motion of stars outside tidal radius is also comparable to that of globular clusters, which suggest that these stars are tidally decoupled from the globular clusters. We manually measure chemical abundances for the clusters and extra-tidal stars, and discuss the association of extra-tidal stars with the clusters.

• Journal of the Korean Magnetic Resonance Society
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• v.1 no.1
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• pp.7-20
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• 1997

The mapping of the spin-spin relaxation time T2 in pixed-by-pixel was suggested as a quantitative diagnostic tool in medicine. Although the CPMG pulse sequence has been known to be the best pulse sequence for T2 measurement in physics NMR, the supplied pulse sequence by the manufacture of MRI system was able to obtain the maximum of 4 CPMG images. Eight or more images with different echo time TEs are required to construct a reliable T2 map, so that two or more acquisitions were required, which easily took more than 10 minutes. 4-echo CPMG imaging pulse sequence was modified to generate the maximum of 8 MR images with evenly spaced echo time TEs. In human MR imaging, since patients tend to move at least several pixels between the different acquisitions, 8-echo CPMG imaging sequence reduces the acquisition time and may remove any misregistration of each pixel's signal for the fitting T2. The resultant T2 maps using the theoretically simulated images and using the MR images of the human brain suggested that 8 echo CPMG sequence with short echo spacing such as 17∼20 msec can give the reliable T2 map.

• The KIPS Transactions:PartD
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• v.8D no.4
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• pp.367-376
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• 2001

For the electronic map service by wireless, the existing map database cannot be used directly. This is because, the data volume of a map is too big to transfer by wireless and although the map is transferred successfully, the devices to display the map usually don’t have enough resources as the ones for desktop computers. It is also not acceptable to construct map database for the exclusive use of wireless service because of the vast cost. We propose new technique to generate a map for wireless service dynamically, from the existing map database. This technique includes the generalization method to reduce the map data volume and filtering method to guarantee that the data volume don’t exceed the limit of bandwidth. The generalization is performed in 3 steps :ㅁ step of merging the layers, a step of reducing the size of spatial objects, and a step of processing user interface. The filtering is performed by 2 module, counter and selector module. The counter module checks whether the data blume of generated map by generalization, exceeds the bandwidth limit. The selector module eliminates the excess objects and selects the rest, on the basis of distance.

• BMB Reports
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• v.47 no.12
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• pp.685-690
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• 2014

The Ras/Raf/MEK/Erk signaling pathway is important for regulation of cell growth, proliferation, differentiation, survival, and apoptosis in response to a variety of extracellular stimuli. Lack of Erk MAPK activation is observed in several cancer cells despite active activation of Ras. However, little is known about the modulation of Erk1/2 activity by active Ras. Here, we show that overexpression of active H-Ras (H-RasG12R) in NIH3T3 fibroblasts impaired FGF2-induced Erk1/2 phosphorylation, as compared to wild-type cells. Northern blot analysis revealed that prolonged expression of active Ras increased MAP kinase phosphatase 3 (MKP3) mRNA expression, a negative regulator of Erk MAPK. Inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway abrogated active Ras-induced up-regulation of MKP3 expression, leading to the rescue of Erk1/2 phosphorylation. Our results demonstrated that the Ras/Raf/MEK/Erk signaling cascade is negatively regulated by the PI3K/Aktdependent transcriptional activation of the MKP3 gene.