• Dementia and Neurocognitive Disorders
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• v.17 no.4
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• pp.163-173
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• 2018

Background and Purpose: Behavioral variant frontotemporal dementia (bvFTD) is a subtype of frontotemporal dementia, which has clinical symptoms of progressive personality and behavioral changes with deterioration of social cognition and executive functions. The pathology of bvFTD is known to be tauopathy or TDP-43 equally. We analyzed the $^{18}F-THK5351$ positron emission tomography (PET) scans, which were recently developed tau PET, in patients with clinically-diagnosed bvFTD. Methods: Forty-eight participants, including participants with behavioral variant frontotemporal dementia (bvFTD, n=3), Alzheimer's disease (AD, n=21) and normal cognition (NC, n=24) who completed 3T magnetic resonance images, $^{18}F-THK5351$ PET scans, and detailed neuropsychological tests were included in the study. Voxel-wise statistical analysis and region of interest (ROI)-based analyses were performed to evaluate the retention of THK in bvFTD patients. Results: In the voxel-based and ROI-based analyses, patients with bvFTD showed greater THK retention in the prefrontal, medial frontal, orbitofrontal, anterior cingulate, insula, anterior inferior temporal and striatum regions compared to NC participants. Left-right asymmetry was noted in the bvFTD patients. A patient with extrapyramidal symptoms showed much greater THK retention in the brainstem. Conclusions: The distribution of THK retention in the bvFTD patients was mainly in the frontal, insula, anterior temporal, and striatum regions which are known to be the brain regions corresponding to the clinical symptoms of bvFTD. Our study suggests that $^{18}F-THK5351$ PET imaging could be a supportive tool for diagnosis of bvFTD.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.99-101
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• 2008

At 21st century, material development concepts were changed to fulfill the environmental friendly demands. This study is to study the effect of pressurized nitrogen gas and manganese in high nitrogen austenitic stainless steel(HNS) in which N and Mn elements substitute the nickel element. 100kg HNS ingots were made by Pressurized Vacuum Induction Melting(P-VIM) and were forged according to free forging process. As forged HNS were hot and cold rolled by pilot scale rolling machine. Depending on the rolling condition, the mechanical properties of HNS were changed. The roll thrust and sheet folding showed asymmetry condition between work and drive side during cold and hot rolling. The purpose of this study are to improve workability the hot and cold rolling machine and to set the conditions for establishing the rolling process.

• Speech Sciences
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• v.11 no.1
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• pp.87-103
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• 2004

This study investigates Korean listeners' perception of the English stop epenthesis between the sonorant and fricative segments. Specifically this study investigates 1) how often English epenthetic stops are perceived by native Korean listeners, given the fact that Korean does not allow consonant clusters in codas; and 2) whether perception of the epenthetic stops, which are optional phonetic variations, not phonemes, could be improved without any explicit training. 120 English non-words with a mono-syllable structure of CVC1C2, where C1=/m, n, $\eta$, 1/, and C2=/s, $\theta$, $\int$/, were given to two groups of native Korean listeners, and they were asked to detect the target stops such as [p], [t], and [k]. The number of their responses were computed to determine how often listeners succeed in recovering the string of segments produced by the native English speaker. The results of the present study show that English epenthetic stops are poorly identified by native Korean listeners with low English proficiency, even in the case where stimuli with strong acoustic cues are provided with, but perception of epenthetic stops is closely related with listeners' English proficiency, showing the possibility of the improvement of perception. It further shows that perception of epenthetic stops shows asymmetry between coronal and non-coronal consonants.

• Archives of Pharmacal Research
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• v.6 no.2
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• pp.115-121
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• 1983

Cholesteryl p-[3-(2-chloroethyl_-3-nitrosoureido] phenylthioaccetate (2) was synthesized : an intermediate, p-[3(2-chloroethyl_-3-nitrosoureido] phenylthioacetic acid (1) is a congener of an antitumor chlorambucil which both the -CH$_{2}$CH$_{2}$-linkage and -N(CH$_{2}$CH$_{2}$Cl)$_{2}$ group of chlorambucil molecule is doubly modified into the respective -S-linkage and -NH-CO-NNO-CH$_{2}$CH$_{2}$CL group. The attackment of cholesterol moiety as a carrier group to p-[3-(2-chloroethyl-3nitrosoureido] phenylthioacetic acid was accomplished through the esterification of cholesterol with p-[3-(2-chloroethyl-3-nitrosoureido] phenylthioacetyl chloride which was obtained from the treatment of p-[3-(2-chloroethyl)-3-nitrosourei-do] phenylthioaceticacid with SOCL$_{2}$, p-[3-(2-chloroethyl)ureido]]-phenythioacetic acid was nitrosated with NaNO$_{2}$ IN 98-100% HCOOH to give exclusively p-[3-(2-chloroethyl_-3-nitrosoureido] phenylthioacetic acid. Antitumor evaluation of compounds, 1 and 2 on L 1210 leukemia did show significant activity (ED$_{40}$ : 1.14.mu./ml and 8.4.mu.g/ml, repectively). Further studies were subjected..

• Journal of the Korean Magnetics Society
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• v.7 no.5
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• pp.225-231
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• 1997

Sulphur Spinel $Co_{0.95}Fe_{0.05}Cr_2S_4$ has been studied with Mossbauer Spectroscopy between 4.2 K and room temperature. The $Fe^{2+}$ ion in a tetrahedral site is the Jahn-Teller active and the dynamic Jahn-Teller distortion starts below the magnetic ordering temperature. The distortion cause a quadrupole shift to appear which increases with decreasing temperature. The magnetic hyperfine field has a maximum at 100 k and then decreases with decreasing temperature. The magnitude of the interaction ratio R between the electric quadrupole and magnetic dipole interaction increases from 0 near the magnetic ordering temperature to 5.4 at 4.2 K. The optimum values of 0, the polar angle of the magnetic hyperfine field with respect to the principle axis of the electric field gradient (EFG) remains zero and the asymmetry of the EFG n is about 0.25. The simulations of Mossbauer spectra coincidence with the experimental results.

• Journal of Korean Critical Care Nursing
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• v.9 no.1
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• pp.51-65
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• 2016

Purpose: This study aimed to estimate the pooled prevalence of workplace bullying among nurses and examine the effect of moderate factors. Methods: Studies that assessed nursing workplace bullying using the negative act questionnaire developed by Einarsen et al. were searched for in 8 databases. The pooled prevalence was calculated with overall event rate and meta-ANOVA was performed for subgroup analysis. A funnel plot and Egger's linear regression asymmetry test were performed to confirm the publication bias of meta-analyzed studies. Results: A total of 23 studies (N=11,748) were included in the systematic review, and 14 studies (N=4,585) that reported prevalence using operational criteria of victim were selected for meta-analysis. The pooled prevalence of workplace bullying was 22.2% (95% CI: 19.0~25.7). Domestic studies reported lower prevalence than international studies (18.6% vs. 27.0%, Q=8.75, p=.003). The prevalences were different according to publication year (30.6% in 2008~2010, 19.5% in 2011~2014, 21.8% in 2015, Q=11.89, p=.003). Studies that recruited only new nurses reported higher prevalence than others (28.4% vs. 20.6%, Q=3.92, p=.048). Publication bias was not found. Conclusions: Workplace bullying is prevalent in the nursing profession, and is more serious for new graduate nurses. Individual and organizational measures for preventing workplace bullying among nurses need to be sought.

• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.287-293
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• 2016

The equatorial region of the Earth's ionosphere exhibits large temporal variations in electron density that have significant implications on satellite signal transmissions. In this paper, the first observation results of the variations in the trough of the equatorial ionospheric anomaly at the permanent Global Navigation Satellite System (GNSS) site in Chuuk (Geographic: $7.5^{\circ}N$, $151.9^{\circ}E$; Geomagnetic: $0.4^{\circ}N$) are presented. It was found that the daytime Global Positioning System (GPS) total electron content (TEC) values vary according to the 27 day period of solar rotation, and that these trends show sharp contrast with those of summer. The amplitudes of the semi-annual anomaly were 12.4 TECU (33 %) on $19^{th}$ of March and 8.8 TECU (23 %) on $25^{th}$ of October respectively, with a yearly averaged value of 38.0 TECU. The equinoctial asymmetry at the March equinox was higher than that at the October equinox rather than the November equinox. Daily mean TEC values were higher in December than in June, which could be interpreted as annual or winter anomalies. The nighttime GPS TEC enhancements during 20:00-24:00 LT also exhibited the semi-annual variation. The pre-midnight TEC enhancement could be explained with the slow loss process of electron density that is largely produced during the daytime of equinox. However, the significant peaks around 22:00-23:00 LT at the spring equinox require other mechanisms other than the slow loss process of the electron density.

• KDI Journal of Economic Policy
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• v.12 no.1
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• pp.127-148
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• 1990

A Milgrom-Roberts style signalling model of limit pricing is developed to analyze the possibility and the scope of limit pricing in general, noncooperative oligopolies. The model contains multiple incumbent firms facing a potential entrant and assumes an information asymmetry between incombents and the potential entrant about the market demand. There are two periods in the model. In period 1, n incumbent firms simultaneously and noncooperatively choose quantities. At the end of period 1, the potential entrant observes the market price and makes an entry decision. In period 2, depending on the entry decision of the entrant, n' or (n+1) firms choose quantities again before the game terminates. Since the choice of incumbent firms in period 1 depends on their information about demand, the market price in period 1 conveys information about the market demand. Thus, there is a systematic link between the market price and the profitability of entry. Using Bayes-Nash equilibrium as the solution concept, we find that there exist some demand conditions under which incumbent firms will limit price. In symmetric equilibria, incumbent firms each produce an output that is greater than the Cournot output and induce a price that is below the Cournot price. In doing so, each incumbent firm refrains from maximizing short-run profit and supplies a public good that is entry deterrence. The reason that entry is deterred by such a reduced price is that it conveys information about the demand of the industry that is unfavorable to the entrant. This establishes the possibility of limit pricing by noncooperative oligopolists in a setting that is fully rational, and also generalizes the result of Milgrom and Roberts to general oligopolies, confirming Bain's intuition. Limit pricing by incumbents explained above can be interpreted as a form of credible collusion in which each firm voluntarily deviates from myopic optimization in order to deter entry using their superior information. This type of implicit collusion differs from Folk-theorem type collusions in many ways and suggests that a collusion can be a credible one even in finite games as long as there is information asymmetry. Another important result is that as the number of incumbent firms approaches infinity, or as the industry approaches a competitive one, the probability that limit pricing occurs converges to zero and the probability of entry converges to that under complete information. This limit result confirms the intuition that as the number of agents sharing the same private information increases, the value of the private information decreases, and the probability that the information gets revealed increases. This limit result also supports the conventional belief that there is no entry problem in a competitive market. Considering the fact that limit pricing is generally believed to occur at an early stage of an industry and the fact that many industries in Korea are oligopolies in their infant stages, the theoretical results of this paper suggest that we should pay attention to the possibility of implicit collusion by incumbent firms aimed at deterring new entry using superior information. The long-term loss to the Korean economy from limit pricing can be very large if the industry in question is a part of the world market and the domestic potential entrant whose entry is deterred could .have developed into a competitor in the world market. In this case, the long-term loss to the Korean economy should include the lost opportunity in the world market in addition to the domestic long-run welfare loss.

• Animal Bioscience
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• v.34 no.5
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• pp.880-885
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• 2021

Objective: Omasum is an important site for the absorption of short chain fatty acids. The major route for the transport of acetate is via sodium hydrogen exchanger (NHE). However, a discrepancy in the symmetry of sodium and acetate transport has been previously reported, the mechanism of which is unclear. In this study, we investigated the possible role of carbonic anhydrase (CA) for this asymmetry. Methods: Omasal tissues were isolated from healthy sheep (N = 3) and divided into four groups; pH 7.4 and 6.4 alone and in combination with Ethoxzolamide. Electrophysiological measurements were made using Ussing chamber and the electrical measurements were made using computer controlled voltage clamp apparatus. Effect(s) of CA inhibitor on acetate and sodium transport flux rate of Na22 and 14C-acetate was measured in three different flux time periods. Data were presented as mean±standard deviation and level of significance was ascertained at p≤0.05. Results: Mucosal to serosal flux of Na (JmsNa) was greater than mucosal to serosal flux of acetate (JmsAc) when the pH was decreased from 7.4 to 6.4. However, the addition of CA inhibitor almost completely abolished this discrepancy (JmsNa ≈ JmsAc). Conclusion: The results of the present study suggest that the additional protons required to drive the NHE were provided by the CA enzyme in the isolated omasal epithelium. The findings of this study also suggest that the functions of CA may be exploited for better absorption in omasum.

• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.18-21
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• 2007

The hexagonal $HoMn_{1-x}-Fe_xO_3$(x=0.00, 0.05) thin films were prepared using pulsed laser deposition(PLD) method on $Pt/Ti/SiO_2/Si$ substrate. The microstructure and magnetic properties have been studied by x-ray diffraction(XRD), atomic force microscopy (AFH), scanning electron microscope(SEM:), x-ray photoelectron spectroscopy(XPS), and conversion electron $M\"{o}ssbauer$ spectroscopy(CEMS). From the analysis of the x-ray diffraction patterns, the crystal structure for all films was found to be a hexagonal($P6_3cm$), which was preferentially grown along(110) direction. The lattice constant $c_0$ of the film with x=0.05 was close to that of single crystal, whereas lattice constant $a_0$ with respect to single crystal shows a slight decrease. This difference of lattice parameters between film and single crystal was caused by the lattice mismatch between the film and $Pt/Ti/SiO_2/Si$ substrate. Conversion electron $M\"{o}ssbauer$ spectrum of $HoMn_{0.95}Fe_{0.05}O_3$ thin film shows an asymmetry doublet absorption ratio at room temperature, which is due to the oriented direction of crystallographic domains. This is corresponding with analysis of x-ray diffraction. The quadrupole splitting(${\Delta}E_Q$) at room temperature is found to be $1.62{\pm}0.01mm/s$. This large ${\Delta}E_Q$ was caused by asymmetry environment surrounding Fe ion.