• Journal of KIISE:Computing Practices and Letters
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• v.6 no.4
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• pp.411-420
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• 2000

The performance of soft handoffs of CDMA mobile communication systems is potentially determined by several factors such as handoff-related system parameters (T_ADD, T_DROP, T_COMP, T_TDROP), mobile stations' mobility, service areas, capacity of base stations. Due to the importance of handoffs in mobile communications, several methods have been proposed and tested through computer simulations to prove the efficiency of proposed methods. Different assumptions on the above mentioned factors often produce different simulation results. Therefore, the credibility of a simulation result is directly determined by the objectivity of the assumptions made by the simulation. This paper proposes a new soft handoff method that controls handoff delay time based on a mobile station's speed, and compares it with the current method of CDMA systems. The simulation results showed that the new method is much more efficient for mobile stations that are free in their moving direction and space than for those restricted in their moving direction and space. In addition, the results showed that even the same handoff method may produces different simulation results depending on whether a service area is modeled as two-dimensional space or three-dimensional space. These results indicate the importance of suitable models of user mobility, especially the movement types and space allowed for mobile stations, which have been neglected in simulation studies of mobile communications.

• Communications of the Korean Mathematical Society
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• v.20 no.3
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• pp.427-436
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• 2005

Let (R, m) be a 2-dimensional regular local ring with algebraically closed residue field R/m. Let K be the quotient field of R and v be a prime divisor of R, i.e., a valuation of K which is birationally dominating R and residually transcendental over R. Zariski showed that there are finitely many simple v-ideals $m=P_0\;{\supset}\;P_1\;{\supset}\;{\cdotS}\;{\supset}\;P_t=P$ and all the other v-ideals are uniquely factored into a product of those simple ones. It then was also shown by Lipman that the predecessor of the smallest simple v-ideal P is either simple (P is free) or the product of two simple v-ideals (P is satellite), that the sequence of v-ideals between the maximal ideal and the smallest simple v-ideal P is saturated, and that the v-value of the maximal ideal is the m-adic order of P. Let m = (x, y) and denote the v-value difference |v(x) - v(y)| by $n_v$. In this paper, if the m-adic order of P is 2, we show that $O(P_i)\;=\;1\;for\;1\;{\leq}\;i\; {\leq}\;{\lceil}\;{\frac{b+1}{2}}{\rceil}\;and\;O(P_i)\;=2\;for\;{\lceil}\;\frac{b+3}{2}\rceil\;{\leq}\;i\;\leq\;t,\;where\;b=n_v$. We also show that $n_w\;=\;n_v$ when w is the prime divisor associated to a simple v-ideal $Q\;{\supset}\;P$ of order 2 and that w(R) = v(R) as well.

• Journal of Gastric Cancer
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• v.18 no.3
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• pp.218-229
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• 2018

Purpose: This study investigated whether the metabolic avidity of primary tumors and/or metastatic lymph nodes (LNs) measured by $^{18}F$-fluorodeoxyglucose ($^{18}F-FDG$) positron emission tomography/computed tomography (PET/CT) was related to survival after surgery in patients with advanced gastric cancer (AGC). Materials and Methods: One hundred sixty-eight patients with AGC who underwent preoperative $^{18}F-FDG$ PET/CT and curative resection were included. The $^{18}F-FDG$ avidity of the primary gastric tumor and LNs was determined quantitatively and qualitatively. The diagnostic performance of $^{18}F-FDG$ PET/CT was calculated, and the prognostic significance of $^{18}F-FDG$ avidity for recurrence-free survival (RFS) and overall survival (OS) was assessed. Results: In all, 51 (30.4%) patients experienced recurrence, and 32 (19.0%) died during follow-up (median follow-up duration, 35 months; range, 3-81 months); 119 (70.8%) and 33 (19.6%) patients showed $^{18}F-FDG$-avid primary tumors and LNs, respectively. $^{18}F-FDG$ PET/CT showed high sensitivity (73.8%) for the detection of advanced pathologic T ($pT{\geq}3$) stage and high specificity (92.2%) for the detection of advanced pN (${\geq}2$) stage. $^{18}F-FDG$ avidity of LNs was significantly associated with RFS (P=0.012), whereas that of primary tumors did not show significance (P=0.532). Univariate and multivariate analyses revealed that $^{18}F-FDG$ avidity of LNs was an independent prognostic factor for RFS (hazard ratio=2.068; P=0.029). Conclusions: $^{18}F-FDG$ avidity of LNs is an independent prognostic factor for predicting RFS. Preoperative $^{18}F-FDG$ PET/CT can be used to determine the risk and prognosis of patients with AGC after curative resection.

• Microbiology and Biotechnology Letters
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• v.40 no.4
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• pp.333-338
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• 2012

Lichens are a symbiosis between fungi, algae and cyanobacteria. Our group recently studied the antioxidant properties of some bacterial species isolated from Arctic lichens and we confirmed that they possess high antioxidant activities. In this paper, we investigated the antioxidant capacity of 5 microorganisms newly isolated from 4 Arctic lichen species, Cladonia sp., Sterocaulon sp., Umbilicaria sp. and Cetraria sp., using various solvent extractions. We carried out 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging activity test and ferric reducing antioxidant power (FRAP) assay. Also total phenolic and flavonoid content assays were performed. Among the bacterial culture extracts of the tested lichen-microorganisms, ethyl acetate extracts of Burkholderia sordidicola S5-B(T) had not only a high antioxidant activity (72.9%) when compared with the ascorbic acid used as the control (51.3%) in the DPPH assay, but also a high amount of phenolic content as well as flavonoid content. As a result, these lichen-microorganisms may be potentially useful sources of natural antioxidants.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1315-1329
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• 2015

The objective of this study was to investigate anticytotoxic and antioxidatative capacities of ethanol extracts from Acer tegmentosum Maxim (A. tegmentosum) stem in vitro. The extract at concentration of 200 ug/mL inhibited 10 and 20 ug/mL arsenic trioxide-induced cytotoxicity of HepG2 cells by 79.3 and 57.5%, respectively. The extract at concentration of 200 ug/mL inhibited 0.2 and 0.5 mM t-BHP-induced cytotoxicity of HepG2 cells by 66.3 and 35.7%, respectively. Antioxidative effects of the extract were examined via measurement of ABTS, superoxide, and peroxyl radical scavenging activities. ABTS radical scavenging activity of the extract was higher than that of ${\alpha}$-tocopherol. Superoxide scavenging activity of the extract was higher than that of catechin. Oxygen radical absorbance capacity of the extract was higher than that of ascorbic acid. Cupric reducing antioxidant capacity of the extract was higher than that of ${\alpha}$-tocopherol. The extract at concentrations of 100 and $500{\mu}g/mL$ inhibited 10 mM t-BHP-induced lipid peroxidation of HepG2 cells by 38.2 and 80.7%, respectively. The extract prevented supercoiled DNA strand breakage induced by hydroxyl or peroxyl radical. Total phenolic and flavonoid contents of the extract at concentration of $100{\mu}g/mL$ were 71.3 nmol/mL gallic acid and 18.8 nmol/mL catechin equivalents, respectively. Thus, strong cytoprotective and antioxidant effects of A. tegmentosum stem extract seem to be due to, at least in part, the prevention from free radicals-induced oxidation as well as high levels in polyphenolic contents.

• Parasites, Hosts and Diseases
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• v.48 no.3
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• pp.267-270
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• 2010

The principal objective of this study was to investigate the prevalence of toxoplasmosis in household and stray cats in Seoul, Republic of Korea. We collected blood samples from 72 stray and 80 household cats, and all samples were examined by ELISA and nested peR. The overall positive rates of Toxoplasma gondii in stray cats were 38.9% (28/72), with 15.3% (11/72) in ELISA and 30.6% (22/72) in peR. The positive rate in male stray cats was Slightly higher than that of female stray cats. The highest positive rate of T. gondii infection was noted in Gangnam and Songpa populations in ELISA and in Gwangjin population in PCR. In household cats, however, we could not detect any specific antibodies or DNA for T. gondii. In conclusion, we recognized that the infection rate of toxoplasmosis in stray cats in Seoul was considerably high but household cats were free from infection.

• Bulletin of the Society of Naval Architects of Korea
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• v.12 no.2
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• pp.35-42
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• 1975

This paper investigates the distribution of stress and its behavior at the Root Toe in fillet welding joint. Furthermore, the stress components and principal stresses in the fillet welds are calculated by the finite element method. The distribution of stresses obtained numerically by means of the finite element method is also compared with the experimental results of two dimensional photoelasticity. A Cover plate type and Center block type of fillet welds are used as models for the numerical calculations covering the variations of 2 W/M(thickness of main plate/thickness of cover plate)=1 through 2W/M=4. The results obtained in these studies are summarized as follows; 1) When W2/M values become small, the stress concentration factors of the Root are larger than of the Toe in a C-type. Its critical value is 2W/M=3.00. However, no critical value exists in a T-type. 2) For 2W/M Values being avove 3.5 in a C-type and above 4.0 in a T-type, $K_R$ and $K_{\tau}$ become 1. 3) According to the differences of 2W/M values, the differences in stress become increasing in the Root but become decreasing in the Toe. These differences, however, disappear as the free boundary surface is approached. 4) The stress concentration factors of both the Root and Toe obtained by means of the finite element method have somewhat lower values than obtained by the photoelasiticity. But their principal stress directions coincide in either method. 5) It proves beneficial to employ the finite element method for two-dimensional plane stress analysis in front fillet welding joint.

• Korean Journal of Biological Psychiatry
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• v.26 no.1
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• pp.14-21
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• 2019

Objectives Thyroid hormone deficiency during the neurodevelopmental period can impair brain development and induce psychiatric symptoms. This study examined the association between thyroid dysfunction and the severity of symptoms in schizophrenia patients, and the treatment response of patients with schizophrenia. Methods Three hundred thirty-eight schizophrenia patients, with no prior history of thyroid disease or taking medication associated with it, were studied. We assessed the blood thyroid hormone level, the Brief Psychiatric Rating Scale (BPRS) scores on the day of admission and discharge, admission period, dose of administered antipsychotics, and the number of antipsychotic combinations. The collected data were subsequently analyzed using the Kruskal-Wallis test and Pearson's chi-square test. Results The percentage of schizophrenia patients who presented with abnormal thyroid hormone level was 24.6%. High total triiodothyronine (TT3) (p = 0.003), low TT3 (p = 0.001), and high free thyroxine (fT4) (p < 0.001) groups showed a higher BPRS score on admission than did the normal thyroid hormone group, while thyroid stimulating hormone (TSH) levels were not significantly correlated with the severity of symptoms. Furthermore, thyroid hormone was not associated with the treatment response assessed by the rate of BPRS score reduction, admission days, use of clozapine, and dose of antipsychotics. Conclusions The TT3 and fT4 hormone levels were significantly associated with the severity of symptoms in schizophrenia patients. These relations suggested that thyroid dysfunction may be associated with the severity of schizophrenia. And hence, further analysis of the results of the thyroid function test, which is commonly used in cases of psychiatric admission, is required.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.558-567
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• 2019

This study examined the effects of complex dance program(ballet, contemporary dance, yoga) on the body composition, BDNF, and serotonin of delivery women, by providing this program for 12 weeks to 14 women(within one year delivery: seven woman, 1-3 years after delivery: seven women). In the results of body composition, in the main effects in accordance with period, both groups showed significant decreases of body fat percentage. The fat-free mass was significantly increased in the group of women within one year after childbirth(t=3.821, p=.009). Regarding BDNF and serotonin, there were no interactive effects between groups and periods while the main effects did not show differences between groups and periods(p>.05). In the results of correlation analysis and regression analysis on BDNF, body composition, and serotonin, the BDNF and serotonin showed the positive correlation(p=.025). In the results of simple regression analysis, the explanatory power was 17.9%(r=.424, $r^2=.179$).

• Polymer(Korea)
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• v.24 no.6
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• pp.886-892
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• 2000

Poly(4-vinyl phenol) (PVPh) was neutralized by LiOH and PVPh ionomers (PVPh-Li) with different Li neutralization extents were synthesized. The variation in $T_{g}$ with Li neutralization was determined by DSC and the results show that the $T_{g}$ increases by 3.$8^{\circ}C$ per Li mol%. When comparing this result with the 3.$2^{\circ}C$ per Na mol% reported for poly (styrene-co-hydroxy styrene), the greater value for PVPh-Li may be due to a strong interaction between unneutralized free -OH and -OLi produced. No distinct small angle X-ray scattering (SAXS) peak was observed for these PVPh ionomers in bulk. In the 50/50 blend of PVPh-Li with PVPh, the miscibile blend was obtained when the Li neutralization in PVPh-Li was 10 mol%. On the contrary, the 50/50 PVPh-Li/PMMA was immiscible when the Li neutralization was 5 mol%. It can be concluded that, even if the starting blend is miscible owing to hydrogen bonding, the miscibility of blend becomes diminished by introducing small amount of ion groups into one of the constituent polymers and the blend can be immiscible as long as any new strong intermolecular ion-dipole interaction is not generated.