• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.47-47
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• 2003

The presenilin 1 (PS1) or PS2 is an essential component of the ${\gamma}$-secretase complex, which mediates the intramembrane proteolysis of selected type-I membrane, including the ${\beta}$-amyloid precursor protein (APP) to yield A${\beta}$. Familial Alzheimer's disease (FAD)-associated mutations in presenilins give rise to an increased production of a highly amyloidogenic A${\beta}$42. In addition to their well-documented proteolytic function, the presenilins play a role in calcium signaling. We have previously reported that presenilin FAD mutations cause highly consistent alterations in intracellular calcium signaling pathways, which include deficits in capacitative calcium entry (CCE), the refilling mechanism for depleted internal calcium stores. However, molecular basis for the presenilin-mediated modulation of CCE remains to be elucidated. In the present study, whole-cell patch clamp method was used to identify a specific calcium-permeable ion channel current(s) that is responsible for the CCE deficits associated with FAD-linked PS1 mutants. Unexpectedly, both voltage-activated and conventional store depletion-activated calcium currents I(CRAC), were absent in HEK293 cells, which were stably transfected either with wild-type or FAD mutant (L286V, M146L, and delta E9) forms of PS1. Recently, magnesium-nucleotide-regulated metal cation current, or I(MagNum), has been described and appears to share many common properties with I(CRAC) including calcium permeability and inhibitor sensitivity (e.g. 2-APB). We have detected I(MagNum) in all 293 cells tested. Interestingly, FAD mutant 293 cells developed only about half of currents compared to PS1 wild type cells.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.150-151
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• 2003

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the progressive deterioration of cognition and memory in association with widespread neuronal loss. AD is supposed to be very often associated with missense mutation located on homologous protein Presenilin (PS1) and (PS2). Up to now, the molecular mechanisms underlying the role of the gene mutation in AD still remain unclear. (omitted)

• Journal of the Microelectronics and Packaging Society
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• v.6 no.2
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• pp.1-12
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• 1999

Brown oxide and/or black oxide layers were formed on the surface of Cu-based leadframe by chemical oxidation of leadframe in hot alkaline solutions, and their growth characteristics were studied. Then, to measure the adhesion strength between leadframe and epoxy molding compound (EMC), oxidized leadframe samples were molded with EMC and machined to form sandwiched double-cantilever beam (SDCB) specimens and pull-out specimens, respectively. Results showed that the adhesion strength of un-oxidized leadframe/EMC interface was inherently very poor but could be increased drastically with the nucleation of acicular CuO precipitates on the surface of leadframe. The presence of smooth faceted $Cu_2O $ on the surfaces of leadframe gave close to zero interfacial fracture toughness (Gc) and reasonable pull strength (PS). A direct correlation between Gc and PS showed that PS can be a measure of Gc only in a limited range.

• Korean Journal of Environmental Agriculture
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• v.21 no.1
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• pp.17-23
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• 2002

In order to investigate effects if loess on the mycellial pellet formation a phosphate-solubilizing fungus. Aspergillus sp. PS-104 was cultured in potato dextrose broth containing loess. The strain formed an amorphous pellet or loose aggregates agitated at a low speed (50 rpm) while spherical and regular pellets at a high speed (150 rpm) The higher concentration of loess was added, the smaller size of a pellet was formed during the submerged culture of the strain. As shown in results, being cultured in the PDB medium supplemented with 1.0% loess the pellet size was maximally reduced to a fourth compared to the control. Evaluating the addition effect of several components of loess such as $SiO_2$, $Fe_2O_3$, $Al_2O_3$, $CaCO_3$, $CaSO_4$ and $MgCO_3$ on the reduction of mycellial pellet size the higher concentration was supplied, the smaller size of pellet was formed except $Al_2O_3$. And the smallest pellet size was recorded at the concentration of 1.0% (W/V) magnesium carbonate.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.111-115
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• 2007

Bimodally porous ${\gamma}$-alumina granules, including mesopores (2~50 nm) and macropores (>50 nm), were prepared by sol-gel and oil-drop method. Mesopores are made from the voids among the alumina crystallites, while macropores are from the space of the decomposed PS particles used as physical templates during the granulation process. The product ${\gamma}$-alumina granules with the average diameter of 2 mm were characterized by FE-SEM, XRD, FT-IR, $N_2$ porosimetry, and universal mechanical testing system.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2178-2182
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• 2011

Recently, the synthesis of ordered macroporous materials has received much attention due to its potential use as photonic band gap materials.$^1$ In this study, we have used the three-dimensional (3D) latex array template impregnated with benzenesulfonic acid (BSA), which is capable of catalyzing the reaction using tetraethyl orthosilicate (TEOS) as a precursor and distilled water. The polystyrene (PS) templates were reacted with TEOS in $scCO_2$ at 40 $^{\circ}C$ and at 80 bar. In the reactor, TEOS was filtrated into the PS particle lattice. After the reaction, porous silica materials were obtained by calcinations of the template. The stability test of the PS template in pure $CO_2$ was conducted before the main experiment. Scanning electron microscopy (SEM) images showed that the reaction in $scCO_2$ takes place only on the particle surface. This new method using $scCO_2$ has advantages over conventional sol-gel processes in its capability to control the fluid properties such as viscosity and interfacial tension. It has been found that the reaction in $scCO_2$ occurs only on the particle surface, making the proposed technique as more rapid and sustainable method of synthesizing inverse opal materials than conventional coating processes in the liquid phase and in the vapor phase.

• BMB Reports
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• v.40 no.5
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• pp.644-648
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• 2007

Exposure of algae or plants to irradiance from above the light saturation point of photosynthesis is known as high light stress. This high light stress induces various responses including photoinhibition of the photosynthetic apparatus. The degree of photoinhibition could be clearly determined by measuring the parameters such as absorption and fluorescence of chromoproteins. In cyanobacteria and red algae, most of the photosystem (PS) II associated light harvesting is performed by a membrane attached complex called the phycobilisome (PBS). The effects of high intensity light (1000-4000 ${\mu}mol$ photons $m^{-2}s^{-1}$) on excitation energy transfer from PBSs to PS II in a cyanobacterium Spirulina platensis were studied by measuring room temperature PC fluorescence emission spectra. High light (3000 ${\mu}mol$ photons $m^{-2}s^{-1}$) stress had a significant effect on PC fluorescence emission spectra. On the other hand, light stress induced an increase in the ratio of PC fluorescence intensity of PBS indicating that light stress inhibits excitation energy transfer from PBS to PS II. The high light treatment to 3000 ${\mu}mol$ photons $m^{-2}s^{-1}$ caused disappearance of 31.5 kDa linker polypeptide which is known to link PC discs together. In addition we observed the similar decrease in the other polypeptide contents. Our data concludes that the Spirulina cells upon light treatment causes alterations in the phycobiliproteins (PBPs) and affects the energy transfer process within the PBSs.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.7
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• pp.43-49
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• 2000

We proposed ADD(Alternate Directional Delay) circuit technique as the DLL(Delay Locked Loop) circuits which technique is established the data valid window(tDV) in DDR(Double Data Rate) Synchronous DRAM. This technique could be decrease area-overhead which it could generated bidirectional clock simultaneously using only one delay chain block. In this paper for high speed memory with relatively small size. This technique decreased area-overhead more 2 times than SMD(Synchronous Mirror Delay) technique. ADD technique has 50ps-140ps jitter and the operation frequency has 166MHz-66MHz range.(at 2.5V, TYP. condition)

• Macromolecular Research
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• v.15 no.5
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• pp.403-411
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• 2007

Monodisperse micron-sized polystyrene (PS) spheres were successfully obtained using a single stage soap-free emulsion method in aqueous media mixed with ethanol (co-solvent) containing NaCI as the electrolyte. The optimum conditions for preparing the monodisperse PS microspheres, using soap-free emulsion polymerization in a water/ethanol mixture with an electrolyte, were studied. The presence of the co-solvent and electrolyte controlled the particle dispersion stability during the polymerization. The microspheres formed using PS, with a weight-average diameter of $2.6{\mu}m$, coefficient of variation of 5.3% and zeta potential of -15.1 eV, were successfully obtained in the presence of 0.1 wt% NaCI, 10 wt% monomer, 0.1 wt% initiator and 95/5 (g/g) of a water/ethanol mixture reacted at $70^{\circ}C$ for 24 h.

• Journal of IKEEE
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• v.17 no.4
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• pp.544-549
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• 2013

This paper describes a modified binary phase detector (Bang-Bang phase detector - BBPD) for jitter reduction in clock and data recovery (CDR) circuits. The proposed PD reduces ripples in the VCO control voltage resulting in reduced jitter for CDR circuits. A 2.5 Gbps CDR circuit with a proposed BBPD has been designed and verified using Dongbu $0.13{\mu}m$ CMOS technology. Simulation shows the CDR with proposed PD recovers data with peak-to-peak jitter of 10.96ps, rms jitter of 0.86ps, and consumes 16.9mW.