• Economic and Environmental Geology
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• v.34 no.1
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• pp.1-12
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• 2001

The crystal structure of biotite-1M from Bancroft, Ontario, was determined by Rietveld refinement method using high-resolution neutron powder diffraction data at -26.3$^{\circ}C$, 2$0^{\circ}C$, 30$0^{\circ}C$, $600^{\circ}C$, 90$0^{\circ}C$. The crystal structure has been refined to a R sub(B) of 5.06%-11.9% and S (Goodness of fitness) of 2.97-3.94. The expansion rate of a, b, c unit cell dimensions with elevated temperature linearly increase to $600^{\circ}C$. The expansivity of the c dimension is $1.61{\times}10^{40}C^{-1}$, while $2.73{\times}10^{50}C^{-1}$ and $5.71{\times}10^{-50}C^{-1}$ for the a and b dimensions, respectively. Thus, the volume increase of the unit cell is dominated by expansion of the c axis as increasing temperature. In contrast to the trend, the expansivity of the dimensions is decreased at 90$0^{\circ}C$. It may be attributed to a change in cation size caused by dehydroxylation-oxidation of $Fe^{2+}$ to $Fe^{3+}$ in vacuum condition at such high temperature. The position of H-proton was determined by the refinement of diffraction pattern at low temperature (-2.63$^{\circ}C$). The position is 0.9103${\AA}$ from the O sub(4) location and located at atomic coordinates (x/a=0.138, y/b=0.5, z/c=0.305) with the OH vector almost normal to plane (001). According to the increase of the temperature, $\alpha$* (tetrahedral rotation angle), $t_{oct}$ (octahedral sheet thickness), mean distance increase except 90$0^{\circ}C$ data. But the trend is less clearly relative to unit cell dimension expansion because the expansion is dominant to the interlayer. Also, ${\Psi}$ (octahedral flattening angle) shows no trends as increasing temperature and it may be because the octahedron (M1, M2) is substituted by Mg and Fe.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.91-99
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• 2018

This paper has proposed a low-noise and high-linear RF receiver supporting TV white space from 470 MHz to 698 MHz), which is implemented in $0.13-{\mu}m$ CMOS technology. It consists of a low-noise amplifier, a RF band-pass filter, a RF amplifier, a passive down-conversion mixer, and a channel-selection low-pass filter. A low-noise amplifier and RF amplifier provide a high voltage gain to improve the sensitivity level. To suppress strong and nearby interferers, two RF filtering schemes have been performed by using a RF BPF and a down-conversion mixer. The proposed LPF has been based on the common-gate topology and adopted a bi-quad cell to achieve -24dB/oct characteristics. In addition, the RF receiver can support the overall TV band by controlling a LO frequency. The simulated results show a voltage gain of 56 dB, a noise figure of less than 2 dB, and an out-of-channel IIP3 of -2.3 dBm. It consumes 37 mA from a 1.5 V supply voltage.

• Polymer(Korea)
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• v.36 no.4
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• pp.478-485
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• 2012

A series of transparent polyimide (PI) nanocomposite films was synthesized from bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTDA) and 1,3-bis(3-aminophenoxy)benzene (BAPB) with various organoclay contents via solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. Varying organoclay loading in a range of 0 to 1.5 wt% produced variations in the optical transparency, morphology, and oxygen barrier property of the hybrids. An optimum oxygen barrier property was observed for the hybrids containing 1.0 wt% Cloisite 30B; these properties were degraded gradually by further increases in the clay content. The PI hybrid films were found to exhibit excellent optical transparency and almost no color. However, the transparency of the hybrid films decreased slightly with increasing organoclay content. Transparent PI hybrid films containing 1.0 wt% Cloisite 30B were stretched equi-biaxially with various stretching ratios in a range of 100-140% to investigate their optical transparency and oxygen permeability in detail; the variations of clay dispersion and morphology were also determined as a function of equi-biaxial stretching ratio. PI hybrid films with ${\geq}120%$ stretching were found to contain homogeneously dispersed clay in the polymer matrix and exfoliated nanocomposites. The highest barrier to oxygen permeation was found at an equi-biaxial stretching ratio of 130%.

• Development and Reproduction
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• v.15 no.1
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• pp.25-30
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• 2011

Embryonic stem (ES) cells can self-renew maintaining the undifferentiated state. Self renewal requires many factors such as Oct4, Sox2, FoxD3, and Nanog. NF-${\kappa}B$ is a transcription factor involved in many biological activities. Expression and activity of NF-${\kappa}B$ increase upon differentiation of ES cells. Reportedly, Nanog protein directly binds to NF-${\kappa}B$ protein and inhibits its activity in ES cells. Here, we found a potential binding site of NF-${\kappa}B$ in the human Nanog promoter and postulated that NF-${\kappa}B$ protein may regulate expression of the Nanog gene. We used human embryonic carcinoma (EC) cells as a model system of ES cells and confirmed decrease of Nanog and increase of NF-${\kappa}B$ upon differentiation induced by retinoic acid. Although deletion analysis on the DNA fragment including NF-${\kappa}B$ binding site suggested involvement of NF-${\kappa}B$ in the negative regulation of the promoter, site-directed mutation of NF-${\kappa}B$ binding site had no effect on the Nanog promoter activity. Furthermore, no direct association of NF-${\kappa}B$ with the Nanog promoter was detected during differentiation. Therefore, we conclude that NF-${\kappa}B$ protein may not be involved in transcriptional regulation of Nanog gene expression in EC cells and possibly in ES cells.

• Biomaterials and Biomechanics in Bioengineering
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• v.3 no.2
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• pp.105-114
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• 2016

The purpose of this study is to evaluate the effects of cryopreservation on dental pulp-derived stem cells (DPSC) viability over a period of three years. Dental pulp-derived stem cells were isolated and cultured from thirty-one healthy teeth. DPSC isolates were assessed for doubling-time and baseline viability prior to cryopreservation and were assessed again at three time points; one week (T1), 18 months (T2), and 36 months (T3). DPSC can be grouped based on their observed doubling times; slow (sDT), intermediate (iDT), and rapid (rDT). Viability results demonstrated all three types of DPSC isolates (sDT, iDT and rDT) exhibit time-dependent reductions in viability following cryopreservation, with the greatest reduction observed among sDT-DPSCs and the smallest observed among the rDT-DPSC isolates. Cryopreserved DPSCs demonstrate time-dependent reductions in cellular viability. Although reductions in viability were smallest at the initial time point (T1) and greatest at the final time point (T3), these changes were markedly different among DPSC isolates with similar doubling times (DTs). Furthermore, the analysis of various DPSC biomarkers - including both intracellular and cell surface markers, revealed differential mRNA expression. More specifically, the relative high expression of Sox-2 was only found only among the rDT isolates, which was associated with the smallest reduction in viability over time. The expression of Oct4 and NANOG were also higher among rDT isolates, however, expression was comparatively lower among the sDT isolates that had the highest reduction in cellular viability over the course of this study. These data may suggest that some biomarkers, including Sox-2, Oct4 and NANOG may have some potential for use as biomarkers that may be associated with either higher or lower cellular viability over long-term storage applications although more research will be needed to confirm these findings.

• Korean Journal of Medicinal Crop Science
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• v.4 no.2
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• pp.139-144
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• 1996

This research was carried out to clarify effects of cultural condition on the content of Alisol B-monoacetate, whose function is antihypercolesterol in blood, and yield in Alisma Rhizomes. When the corm part of Alisma Rhizomes was extracted by shaking extraction at $25^{\circ}C$ and reflux extraction at $40^{\circ}C$ to $100^{\circ}C$ four times, the total content of Alisol B-monoacetate was 0. 402%, 0. 425% and 0. 402% at $25^{\circ}C$, $40^{\circ}C$ and $60^{\circ}C$ respectively. The recovery rate was 97% by three times extraction at $25^{\circ}C$, and 96% and 97% by three times extraction at $40^{\circ}C$ and $60^{\circ}C$ respectively. When the corm was harvested on Oct. 30, the content of Alisol B-monoacetate was 0. 46% but it was increased to 0. 71% on Nov. 30. In the case of Oct. 30, the corms of $S(4{\sim}14g\; FW)$ size were determined to contain the highest level of Alisol B-monoacetate (0. 53%), and the content was decreased as the corn size was increased. This tendency was also adopted on Nov. 30. On the other hand, the content of crude protein and starch was changed rarely by the period of harvest. When the planting depth was $0{\sim}1cm$, the yield was the highest as 206kg/10a, and the yield was decreased as the planting depth was deep. The variation of the content of Alisol B-monoacetate was small as 0. 33% to 0. 39% by planting depth. From the above results it could be concluded that the optimum time for harvest of Alisma Rhizomes is Nov. 30 and the optimum planting depth is $0{\sim}1cm$.

• Current Optics and Photonics
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• v.7 no.1
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• pp.73-82
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• 2023

In this study, we demonstrate ultrahigh-resolution spectral-domain optical coherence tomography with a 200-kHz line rate using a superluminescent diode with a -3-dB bandwidth of 100 nm at 849 nm. To increase the line rate, a subset of the total number of camera pixels is used. In addition, a partial-spectrum detection method is used to obtain OCT images within an imaging depth of 2.1 mm while maintaining ultrahigh axial resolution. The partially detected spectrum has a flat-topped intensity profile, and side lobes occur after fast Fourier transformation. Consequently, we propose and apply the super-Gaussian window function as a new window function, to reduce the side lobes and obtain a result that is close to that of the axial-resolution condition with no window function applied. Upon application of the super-Gaussian window function, the result is close to the ultrahigh axial resolution of 4.2 ㎛ in air, corresponding to 3.1 ㎛ in tissue (n = 1.35).

• Journal of Korean Physical Therapy Science
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• v.3 no.3
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• pp.93-104
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• 1996

The purpose of this study is improvement of clinical practice education through examination of satisfaction on clinical practice of physical therapy students and grasping the factor have on effect on satisfaction of clinical practice. The students of the survey were 328 junior college students and 41 University students selected from 8 junior college and 2 University by questionnaire from Oct. 6 to Oct. 26, 1993. The collected data was analyzed by ANOVA, T-test, Multiple range test (Tukey, LSD, Duncan), principal factor analysis according to purpose of study. The results were as follows : The degree of satisfaction according to the item on clinical practice was low as 0.346 of a total 1.0. The degree of satisfaction of instruction(0.40) revealed to be high. Compared with the degree of satisfaction on contents(0.39), practice environment(0.38), satisfaction after practice(0.36), practice hours(0.35), personalrelations(0.33), problem of practice place(0.31), practice evaluation(0.25) revealed to be low. 1. The degree of satisfaction on clinical practice according to education system was lower junior college than University. 2. The degree of satisfaction on clinical practice according to volitional group and another intention group and another intention group was not different. 3. The degree of satisfaction on clinical practice according to the order of merit was not difference A group, B group, C group, but it of D group was low. 4. The degree of satisfaction on clinical practice according to the time of practise, the group that clinical enforce during a session was higher than the group that it enforce during vacation. 5. The degree of satisfaction on clinical practice according to clinical practice place was high in University hospital and general hospital, but was low in hospital and clinic. 6. The degree of satisfaction on clinical practice according to existence or non-existence of a hospital in affiliation was higher existence a hospital in affiliation group than non-existencea hospital in affiliation group. 7. The degree of satisfaction on clinical practice according to satisfaction of major was high in group of high satisfaction major.

• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.293-299
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• 2011

In this study, we demonstrated Fourier-domain/swept-source optical coherence tomography (FD/SS-OCT) at a center wavelength of 800 nm for in vivo human retinal imaging. A wavelength-swept source was constructed with a semiconductor optical amplifier, a fiber Fabry-Perot tunable filter, isolators, and a fiber coupler in a ring cavity. Our swept source produced a laser output with a tuning range of 42 nm (779 to 821 nm) and an average power of 3.9 mW. The wavelength-swept speed in this configuration with bidirectionality is 2,000 axial scans per second. In addition, we suggested a modified zero-crossing method to achieve equal sample spacing in the wavenumber (k) domain and to increase the image depth range. FD/SS-OCT has a sensitivity of ~89.7 dB and an axial resolution of 10.4 ${\mu}m$ in air. When a retinal image with 2,000 A-lines/frame is obtained, an acquisition speed of 2.0 fps is achieved.

• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.1
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• pp.18-24
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• 1987

This experiment was carried out to investigate the effects of the final cutting time and cutting height on the winter survival, regrowth, and carbohydrate reserves in stubble, and early spring yield of orchardgrass-dominated pasture before and after the winter season. The experiment was conducted at the experimental field of the Livestock Experiment Station, in Suwon, from October 1985 to early 1986. The results obtained are summarized as follows: 1. Regrowth of plant after the final cut increased significantly (P<0.05) with plot of the early cutting time (Oct. 10) and high cutting height at the final. For winter survival, cut plant should regrow over 15cm in plant height. Therefore limit cutting time and cutting height were forced to be on Oct. 25 and at 6-9cm, respectively. 2. Total water soluble carbohydrate (TSC) content in stubble after the final cut was not significantly changed by different cutting time and cutting height. 3. The percentage of dead plant after wintering was found to be high with plot of the late cutting time and low cutting height at the final cut (P<0.05). And the correlation between the percentage of dead plant after wintering and final plant height before wintering was significantly negathe (r = -0.728**). 4. Fresh and DM yield at the early spring after wintering were increased in the plot of the early cutting time and high cutting height (P<0.05) at the final cut. And significantly positive correlation was observed between the early spring yield and final plant height before wintering (r = 0.720**).