• The Korean Journal of Pharmacology
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• v.32 no.2
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• pp.283-292
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• 1996

The spinal dorsal horn is the area where primary afferent fibers terminate and cutaneous sensory information is processed. A number of putative neurotransmitter substances, including excitatory and inhibitory amino acids and peptides, are present in this region. In this study, single neurons of the spinal dorsal horn were acutely isolated and the properties of whole cell current and responses to excitatory and inhibitory neurotransmitters were studied by patch clamp technique. Transverse slice ($(300{\mu}m$) of lumbar spinal cords from young rats$(7{\sim}14\;days)$ were sequentially treated with two pretenses(pronase 0.75 mg/ml and thermolysin 0.75 mg/ml), then single neurons were mechanically dissociated. These neurons showed near-intact morphology such as multipolar, ellipsoidal and bipolar, and pyramidal cells and we recorded the typical whole cell currents of $K^+$, $Ca^{2+}$ and ligand-operated channels from these neurons. Glutamate $(30{\mu}M)$ and N-methyl-D-aspartate(NMDA, $30{\mu}M)$ induced inward currents of $117{\pm}12.4$ pA(n=5) and $49{\pm}6.9$ pA(n=3), respectively. Glycine $(1{\mu}M)$ potentiated glutamate-induced currents $4{\sim}5$ times and NMDA-induced currents $8{\sim}10$ times. In addition, glycine $(30{\mu}M)$ induced Inward current ($31{\pm}6.1$ nA, n=2), which was rapidly desensitized after the peak to a new steady-state level. However, the inward currents induced by ${\gamma}-amino$ butyric acid(GABA, $1{\mu}M$) decreased continuously after the peak($226{\pm}41.6$ pA, n=3) under the similar experimental condition. The ionic currents and pharmacological responses of isolated neurons in this work were similar to those observed in vivo or in vitro spinal cord slice, indicating that acutely isolated neurons could be effectively used for further pharmacological studies.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.611-631
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• 1999

Enviromental geochemisty and heary metal contamination at the Kongjueil mine creek were underaken on the basis of physicohemical properties and mineralogy for various kinds of water (surface, mine and ground water),soil, precipitate and sediment collected of April and December in 1998. Hydrgeochemical composition of the water samples are characterized by relatively significant enricant of Ca+Na, alkiali ions $NO_3$ and Cl inground and surfore water, wheras the mine waters are relatively eneripheral water of the mining creek have the characteristics of the (Ca+Mg)-$(HCO_3+SO_4)$type. The pH of the mine water is high acidity (3.24)and high EC (613$\mu$S/cm)compared with those of surface and ground water. The range of $\delta$D and $\delta^{18}O$ values (relative to SMOW) in the waters are shpwn in -50.2 to -61.6% and -7.0 to -8.6$\textperthousand$(d value=5.8 to 8.7). Using computer program, saturation index of albite, calcite, dolomite in mine water are nearly saturated. The gibbiste, kaolinite and smectite are superaturated in the surface and ground water, respectively. Calculated water-mineral reaction and stabilities suggest that weathing of silicate minerals may be stable kaolinite owing to the continuous water-rock reaction. Geochemical modeling showed that mostly toxic heavy metals may exist larfely in the from of metal-sulfate $(MSO_4\;^2)$and free metal $(M^{2+})$ in nmine water. These metals in the ground and surface water could be formed of $CO_3$ and OH complex ions. The average enrichment indices of water samples are 2.72 of the groundwater, 2.26 of the surface water and 14.15 of the acid mine water, normalizing by surface water composition at the non-mining creek, repectively. Characteristics of some major, minor and rate earth elements (Al/Na, K/Na, V/Ni, Cr/V, Ni/Co, La/Ce, Th/Yb, $La_N/Yb_N$, Co/Th, La/Sc and Sc/Th) in soil and sediment are revealed a narrow range and homogeneous compositions may be explained by acidic to intermediate igneous rocks. And these suggested that sediment source of host granitic gneiss colud be due to rocks of high grade metamorphism originated by sedimentary rocks. Maximum concentrations of environmentally toxic elements in sediment and soil are Fe=53.80 wt.% As=660, Cd=4, Cr=175, Cu=158, Mn=1010, Pb=2933, Sb=4 and Zn=3740 ppm, and extremely high concentrations are found are found in the subsurface soil near the ore dump and precipitates. Normalizing by composition of host granitic gneiss, the average enerichment indices are 3.72 of the sediments, 3.48 of the soils, 10.40 of the precipitates of acid mine drainage and 6.25 of the soils near the main adit. The level of enerichment was very severe in mining drainage sediments, while it was not so great in the soils. mineral composition of soil and sediment near the mining area were partly variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. reddish variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. Reddish brown precipitation mineral in the acid mine drainage identifies by schwertmanite. From the separated mineralgy, soil and sediment are composed of some pyrite, arsenopyite, chalcopyrite, sphalerite, galena, malachite, goethite and various kinds of hydroxied minerals.

• Radiation Oncology Journal
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• v.14 no.4
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• pp.265-279
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• 1996

Damage produced by radiation elicits a complex response in mammalian cells, including growth rate changes and the induction of a variety of genes associated with growth control and apoptosis. At doses of 10,000 cGy or greater, the exposed individual was killed in a matter of minutes to a couple of days, with symptoms consistent with pathology of the central nervous system(CNS) including degenerative changes. The nature of the damage in irradiated cells underlies the unique hazards of ionizing radiation. Radiation injury to CNS is a rare event in clinical medicine, but it is catastrophic for the patient in whom it occurs. The incidence of cerebral necrosis has been reported as high as 16% for doses greater than 6,000 cGy. In this study, the effect of radiation on brain tissue was studied in vivo. Jun and p53 genes in the rat brain were induced by whole body irradiation of rat with 600Co in doses between 1 Gy and 100 Gy and analyzed for expression of jun and p53 genes at the postirradiation time up to 6 hours. Northern analyses were done using 1.8 Kb & 0.8 Kb-pGEM-2-JUN/Eco RI/Pst I fragments, 2.0 Kb-php53B/Bam HI fragment and ,1.1 Kb-pBluescript SK--ACTIN/Eco RI fragment as the digoxigenin or [${\alpha}^{32}P$] dCTPlabeled probes for Jun, p53 and ${\beta}$-actin genes, respectively. Jun gene seemed to be expressed near the threshold levels in 1 hour after irradiation of $^{60}$Co in dose less than 1 Gy and was expressed in maximum at 1 hour after irradiation of $^{60}$Co in dose of 30 Gy. Jun was expressed increasingly with time until 5 or 6 hours after irradiation of $^{60}$Co in doses of 1 Gy and 10 Gy. After irradiation of $^{60}$Co in dose between 20 Gr and 100 Gy, the expression of Jun was however increased to peak in 2 hours and decreased thereafter. p53 gene in this study also seemed to be expressed near the threshold levels in 1 hour after irradiation of $^{60}$Co in dose less than 1 Gy and was expressed in maximum at 6 hours after irradiation of $^{60}$Co in dose of 1 Gy, p53 was expressed increasingly with time until 5 or 6 hours after irradiation of $^{60}$Co in dose between 1 Gy and 40 Gy. After irradiation of $^{60}$Co in doses of 50 Gy and 100 Gy, the expression of p53 was however increased to peak in 2 hours and decreased thereafter. The expression of Jun and p53 genes was not correlative in the brain tissue from rats. It seemed to be very important for the establishment of the optimum conditions for the animal studies relevant to the responses of genes inducible on DNA damage to ionizing radiation in mammalian cells. But there are many limitations to the animal studies such as the ununiform patterns of gene expression from the tissue because of its complex compositions. It is necessary to overcome the limitations for development of in situ Northern analysis.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.87-97
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• 2010

Purpose: The purpose of this study is to investigate the effects of sports vision training on baseball player's visual performance and baseball records. Methods: All subjects were 21 males of high school baseball players, and they participated on eight weeks of sports vision training program. Pre- and post- test results were obtained for static and dynamic visual acuity, static and dynamic stereo acuity, distance and near phoria, fusional reserves, near point of convergence, contrast sensitivity, visual-reaction time. Results: Statical analysis indicated significant improvement in most of mentioned visual variables and baseball records (p<0.001). Conclusions: It can be concluded that the sports vision training program improves visual skills of baseball players, which could lead to improvement in the baseball records. Vison training will be a promotor for baseball player to enhance their performance if proper test instruments and training course is supplied.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.348-351
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• 1995

A modified silicon direct bonding method has been developed alloying an intimate contact between grooved and smooth mirror-polished oxide-free silicon wafers. A regular set of grooves was formed during preparation of heavily doped $p^+$-type grid network by oxide-masking und boron diffusion. Void-free bonded interfaces with filing of the grooves were observed by x-ray diffraction topography, infrared, optical. and scanning electron microscope techniques. The presence of regularly formed grooves in bending plane results in the substantial decrease of dislocation over large areas near the interface. Moreover two strongly misoriented waters could be successfully bonded by new technique. Diodes with bonded a pn-junction yielded a value of the ideality factor n about 1.5 and the uniform distribution of series resistance over the whole area of horded pn-structure. The suitability of the modified technique was confirmed by I - V characteristics of power diodes and reversly switched-on dynistor(RSD) with a working area about $12cm^2$. Both devices demonstrated breakdown voltages close to the calculation values.

• Geophysics and Geophysical Exploration
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• v.12 no.2
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• pp.173-182
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• 2009

In April 2008, KIGAM carried out an ocean-bottom seismometer (OBS) survey in the central Ulleung Basin where strong bottom simulating reflectors (BSRs) were revealed from previous surveys and some gas-hydrate samples were retrieved by direct sampling. The purpose of this survey is to estimate the velocity structure near the BSR in the gas hydrate prospect area using wide-angle seismic data recorded on the ocean-bottom seismometers. Along with the OBS survey, a 2-D seismic survey was performed whereby stratigraphic and preliminary velocity information was obtained. Two methods were applied to wide-angle data for estimating P wave velocity; one is velocity analysis in the $\tau$-p domain and the other is seismic traveltime inversion. A 1-D interval velocity profile was obtained by the first method, which was refined to layered velocity structure by the latter method. A layer stripping method was adopted for modeling and inversion. All velocity profiles at each OBS site clearly show velocity reversal at BSR depths due to the presence of gas hydrates. In addition, we could confirm high velocity in the column/chimney structure.

• Geomechanics and Engineering
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• v.30 no.2
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• pp.169-185
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• 2022

The urbanization and increasing rate of population demands effective means of transportation system (basement and tunnels) as well as high-rise building (resting on piled foundation) for accommodation. Therefore, it unavoidable to construct basements (i.e., excavation) nearby piled foundation. Since the basement excavation inevitably induces soil movement and stress changes in the ground, it may cause differential settlements to nearby piled raft foundation. To understand settlement and load transfer mechanism in the piled raft due to excavation-induced stress release, numerical parametric studies are carried out in this study. The effects of excavation depths (i.e., formation level) relative to piled raft were investigated by simulating the excavation near the pile shaft (i.e., H_e/L_p=0.67), next to (H_e/L_p=1.00) and below the pile toe (H_e/L_p=1.33). In addition, effects of sand density and raft fixity condition were investigated. The computed results have revealed that the induced settlement, tilting, pile lateral movement and load transfer mechanism in the piled raft depends upon the embedded depth of the diaphragm wall. Additional settlement of the piled raft due to excavation can be account for apparent loss of load carrying capacity of the piled raft (ALPC). The highest apparent loss of piled raft capacity ALPC (on the account of induced piled raft settlement) of 50% was calculated in in case of H_e/L_p = 1.33. Furthermore, the induced settlement decreased with increasing the relative density from 30% to 90%. On the contrary, the tilting of the raft increases in denser ground. The larger bending moment and lateral force was induced at the piled heads in fixed and pinned raft condition.

• The Journal of Engineering Geology
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• v.7 no.1
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• pp.63-79
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• 1997

In this study, our purpose is to develop a technique to discriminate artificial explosions from local microearthquakes on the basis of time-frequency domain. To obtain spectral features of artificial explosions and microearthquakes, we used 3-d spectrograms(frequency, time and amplitude) because this is a useful tool to study the frequency content of entire seismic waveforms observed at local and regional distances (e. g., Kim et al., 1994). P and S waves from quarry blasts show that frequency content of dominant amplitude appeared above 10 Hz and Rg phases that are observed at near distance ranges. But P and S waves from microearthquakes have more broad frequency content as well as below 10 Hz. And for discrimination, Pg/Lg spectral ratio is performed below 10 Hz. In order to select time windows we computed group velocity using multiple filter method(MFM) and removed free surface effects from all 3-components data for improving on data quality. Next step, we computed Fast-Fourier transform, and a log average spectral amplitude over seven frequency bands : 0.5 to 3, 2 to 4, 3 to 5, 4 to 6, 5 to 7, 6 to 8 and 8 to 10 Hz. The best separation is observed from 6 to 8 Hz.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.128-133
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• 2008

Phase-change random access memory (PRAM) chip cell phase of amorphous state is rapidly changed to crystal state above 160 Celsius degree within several seconds during Infrared (IR) reflow. Thus, on-board programming method is considered for PRAM chip programming. We demonstrated the functional 512Mb PRAM with 90nm technology using several novel core circuits, such as metal-2 line based global row decoding scheme, PN-diode cells based BL discharge (BLDIS) scheme, and PMOS switch based column decoding scheme. The reverse-state standby current of each PRAM cell is near 10 pA range. The total leak current of 512Mb PRAM chip in standby mode on discharging state can be more than 5 mA. Thus in the proposed BLDIS control, all bitlines (BLs) are in floating state in standby mode, then in active mode, the activated BLs are discharged to low level in the early timing of the active period by the short pulse BLDIS control timing operation. In the conventional sense amplifier, the simultaneous switching activation timing operation invokes the large coupling noise between the VSAREF node and the inner amplification nodes of the sense amplifiers. The coupling noise at VSAREF degrades the sensing voltage margin of the conventional sense amplifier. The merit of the proposed sense amplifier is almost removing the coupling noise at VSAREF from sharing with other sense amplifiers.

• Journal of The Korean Astronomical Society
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• v.55 no.5
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• pp.173-194
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• 2022

We complete the survey for finite-source/point-lens (FSPL) giant-source events in 2016-2019 KMTNet microlensing data. The 30 FSPL events show a clear gap in Einstein radius, 9 𝜇as < 𝜃_E < 26 𝜇as, which is consistent with the gap in Einstein timescales near t_E ~ 0.5 days found by Mróz et al. (2017) in an independent sample of point-source/point-lens (PSPL) events. We demonstrate that the two surveys are consistent. We estimate that the 4 events below this gap are due to a power-law distribution of free-floating planet candidates (FFPs) dN_FFP/d log M = (0.4 ± 0.2) (M/38 M_⊕)^-p/star, with 0.9 ≲ p ≲ 1.2. There are substantially more FFPs than known bound planets, implying that the bound planet power-law index 𝛾 = 0.6 is likely shaped by the ejection process at least as much as by formation. The mass density per decade of FFPs in the Solar neighborhood is of the same order as that of 'Oumuamua-like objects. In particular, if we assume that 'Oumuamua is part of the same process that ejected the FFPs to very wide or unbound orbits, the power-law index is p = 0.89 ± 0.06. If the Solar System's endowment of Neptune-mass objects in Neptune-like orbits is typical, which is consistent with the results of Poleski et al. (2021), then these could account for a substantial fraction of the FFPs in the Neptune-mass range.