• Title/Summary/Keyword: relative frequencies

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Effect of the Surface Oxidation on the Electromagnetic Wave Absorption Behavior of a Fe-based Nanocrystalline Alloy (Fe계 나노결정립 분말의 표면 산화에 따른 전자파 흡수특성)

  • Koo, S.K.;Woo, S.J.;Moon, B.G.;Song, Y.S.;Park, W.W.;Sohn, K.Y.
    • Journal of Powder Materials
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    • v.14 no.5
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    • pp.303-308
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    • 2007
  • The oxidation of $Fe_{73}Si_{16}B_7Nb_3Cu_1$ nanocrystalline powder has been conducted to investigate its influence on the electromagnetic wave absorption characteristics of the soft magnetic material. Oxidation occurred primarily on the surface of nanocrystals. Oxidation reduced the real part of complex permeability due to the reduction of the relative volume of the powder, which otherwise contributes to the permeability. Oxidation reduced the absorption efficiency of the sheet at frequencies over 1GHz, indicating that the relative contribution of skin depth increments to the absorption was not significant. The pulverization and milling process lowered the optimum crystallization temperature of the material by $40{\sim}50^{\circ}C$ because of the internal energy accumulated during the fragmentation and powder thinning processes.

The Characteristics of the Fog and Analysis of the Advection.Radiation Fog by KLAPS in Honam Region (호남지방 안개 특성 및 KLAPS를 통한 이류.복사안개 사례 연구)

  • Won, Hyo-Sung;Yu, Keun-Gi;Ryu, Chan-Su
    • Journal of Integrative Natural Science
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    • v.4 no.4
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    • pp.298-310
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    • 2011
  • Recently the traffics and transportation hazzards by fog are tremendously Increased. There occurred the greater traffic disaster by Dense Fog of Oct.2006. In this study frequent occurrences of advection fogs centerd over Honam Prov are investigated. Increment of transportation during the Fog period for 1996~2005(decade)are statistically analyzed with Honam Prov.'s fogs. For Honam west coast(Gunsan, Mokpo), inland of Honam(Junju, Gwangju, Suncheon), Honam south coast(Wando, Yepsu), Wind, Dew point, Diff. of air and sea temp. relative humidity are classified between 12 hours before and on time of fog with three Dimensional Analysis System(KLAPS). High frequencies of advection-radiation Fog occurrence in western Coasts except for Suncheon. The application of fog characteristics analyzed by KLAPS for denser fog over the western coast in Fall to Fog prediction and special advisory issues. The advection-radiation fog can occure favorably when the moisture index is less than $2^{\circ}C$, relative humidity is greater than 90%, but the moisture depth is under 1.5 km. In addition when the height of 925 hPa is rising, then fog occurs, but for sinking is disappearing.

Experimental study of wave energy extraction by a dual-buoy heaving system

  • Kim, J.;Koh, H.J.;Cho, I.H.;Kim, M.H.;Kweon, H.M.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.9 no.1
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    • pp.25-34
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    • 2017
  • The concentric dual-buoy Wave Energy Converter (WEC), which consists of external buoy (hallow-cylinder) with toroidal appendage and cylindrical internal buoy within the moon-pool is suggested in this research and its performance in various wave conditions is studied. The Linear Electric Generator (LEG), consisting of a permanent magnet and coils, is used as a direct Power Take-Off (PTO) system. To maximize the electrical energy extracted from the PTO system, the relative heave motions between the dual buoys must be highly amplified by the multiple resonance phenomena of dual-buoy and internal-fluid motions. The high-performance range can be widened by distributing those natural frequencies with respect to the peak frequency of the wave spectrum. The performance of the newly developed dual-buoy WEC was measured throughout the systematic 1:5.95-model test in regular and irregular waves conducted in a wave tank at Seoul National University. The model-test results are also validated by an independently developed numerical method.

The Symbolic Consumption in Clothing and Related Factors (청소년들의 상징적 의류제품 소비성향과 관련변수와의 관계연구)

  • 이옥희;홍병숙
    • Journal of the Korean Society of Clothing and Textiles
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    • v.22 no.6
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    • pp.781-792
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    • 1998
  • The purpose of this study was to investigate the factors related to the propensity for symbolic consumption and the effects of materialism, reference group, and social stratification on the symbolic consumption in clothing. Data were administered to 957 adolescence in middle, high school, and college student living in Seoul, Chonju, Sunchon, Yousu, and Kwangyang from May to June 1997. For analysis of the data, frequencies, percentage, means, standard deviation, factor analysis, 1-test, one-way anomia, duncan's multiple range test, and multiple regression analysis were employed. The results of this study can be summarized asfollows. 1) Symbolic consumption, materialism, and reference group were found to have the significant differences according to social stratification groups by objectivemethod. The higher social stratification is, the higher symbolic consumption, materialism, and reference group were. 2) symbolic consumption were proven to have the significant differences according to materiaiism and reference group. The higher materialism and the influence of referencegroup indicated, the higher symbolic consumption. 3)according to the results of the regression analysis examining the relative influences of variables affecting symbolic consumption in clothing, the relative importance of the variables are in order of : the influences of the reference group, materialism, social stratification, status inconsistency type (occupation-income), and their explanatory power totalled 40.0%.

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Immunohistochemistry of Gastrointestinal Endocrine Cells in the Meckel′s Diverticulum of the Bean Goose, Anser fabalis Latham

  • Ku, Sae-Kwang;Lee, Hyeung-Sik;Park, Ki-Dae;Lee, Jae-Hyun
    • Animal cells and systems
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    • v.4 no.4
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    • pp.375-379
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    • 2000
  • The appearance of some gastrointestinal endocrine cells in the Meckel's diverticulum (MD) of the bean goose, Anser fabalis Latham was observed using specific antisera against serotonin, gastrin, cholecystokinin (CCK)-8, glucagon, secretin, somatostatin and human pancreatic polypeptide (HPP) with the peroxidase antiperoxidase (PAP) method. Among these specific antisera, serotonin-, gastrin-, CCK-8-, somatostatin- and HPP-immunoreactive cells were demonstrated in this study. Serotonin-, gastrin- and somatostatin-immunoreactive cells were detected at moderate frequency and CCK-8- and HPP-immunoreactive cells was rare and low frequencies, respectively. These immunoreactive cells were located in the superficial epithelium, intestinal crvpt and intestinal glands with spherical or spindle shaped cells having long cytoplasmic processes (open typed-cell). Mucosal layer of MD was composed of simple columnar epithelium and numerous intestinal glands. In addition, numerous lymphatic tissues were also demonstrated. In conclusion, histological profiles of MD were similar to any parts of the large intestine, especially the cecum, but the appearance, distribution and relative frequency of gastrointestinal endocrine cells were similar to those of upper parts of the small intestine. Although the exact digestive functions were unknown, the finding that the appearance, distribution and relative frequency of gastrointestinal endocrine cells in MD is similar to small intestine may be considered as distinct evidence that this organ may have some digestive functions.

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A numerical study on vibration-based interface debonding detection of CFST columns using an effective wavelet-based feature extraction technique

  • Majid Gholhaki;Borhan Mirzaei;Mohtasham Khanahmadi;Gholamreza Ghodrati Amiri;Omid Rezaifar
    • Steel and Composite Structures
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    • v.53 no.1
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    • pp.45-59
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    • 2024
  • This paper aims to investigate the impact of interfacial debonding on modal dynamic properties such as frequencies and vibration mode shapes. Furthermore, it seeks to identify the specific locations of debonding in rectangular concrete-filled steel tubular (CFST) columns during the subsequent stage of the study. In this study, debonding is defined as a reduction in the elasticity modulus of concrete by a depth of 3 mm at the connection point with the steel tube. Debonding leads to a lack of correlation between primary and secondary shapes of vibration modes and causes a reduction in the natural frequency in all modes. However, directly comparing changes in vibration responses does not allow for the identification of debonding locations. In this study, a novel irregularity detection index (IDI) is proposed based on modal signal processing via the 2D wavelet transform. The suggested index effectively reveals relative irregularity peaks in the form of elevations at the debonding locations. As the severity of damage increases at a specific debonding location, the relative irregularity peaks would increase only at that specific point; in other words, the detection or non-detection of a debonding location using IDI has minimal effects on the identification of other debonding locations.

A Study on Production of Nitrogen Oxides in Plasma Reactors

  • Lim, Gye-Gyu
    • Journal of Korean Society for Atmospheric Environment
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    • v.17 no.E3
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    • pp.91-99
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    • 2001
  • Plasma reactor was used to generate a high potential difference between two surfaces of concentric pyrex tubes by electrical current. The annular gap of the reactor was calculated by trial and error from the breakdown voltage equation and set at 0.45 cm. The overall objective of this research was to know the effects of the frequency, humidity, and residence time on the formation of nitrogen oxides in a plasma reactor. The primary voltage varied from 50 to 90 volts and the frequency was varied in increments of 10 Hz from 60 to 650 Hz at the primary voltage of 90. The increase in the secondary voltage was not linear but exponential at high frequencies. At a maximum concentration of about 745 ppm, the frequency and secondary voltage was 600 Hz and 4,200 volts, respectively. All tests for the effects of humidity on NO$_{x}$ production were performed at the optimal setting of 90 colts and 600 Hz frequency. Since the NO$_{x}$ production was not an one dimensional phenomenon, competing reactions were assumed to occur in the discharge chamber. The sharp peak concentration of 1,810 ppm was observed at 38% of relative humidity, The enhanced production was choked off, and the production rate rapidly dropped to 3 ppm at above 40% of relative humidity. It is assumed that the corona attacks the most vulnerable molecules in the reaction chamber before attacking other more lightly bonded molecules, possibly at humidities above 38% and the optimized 90 volt setting. Thus, there was not enough energy left after attacking all water molecules to decompose an appreciable amount of $N_2$. If nitrogen breakdown does not occur, then oxides of nitrogen are not likely to be produced.ced.

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Cytochrome P4501A1 and Glutathione S-transferase M1 Polymorphism and Individual Genetic Susceptibility to the Korean head and neck Cancer patients (한국인 두경부암 환자에서 CYP1A1 및 GSTM1 유전자 다형성 분석에 의한 유전적 감수성에 대한 연구)

  • 김현준;채현기;태경;공구
    • Environmental Mutagens and Carcinogens
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    • v.20 no.1
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    • pp.26-33
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    • 2000
  • Genetic polymorphisms of metabolizing enzymes to chemical carcinogens have been recognized as a major important host factors in human cancers. To datermine the frequencies of genotypes of CYP1A1 and GSTM1 metabolizing enzymes in healthy controls and head and neck cancer patients in Korean and to identify the relative high risk genotypes of these metabolizing enzymes to head and neck cancer, we have analyzed 133 head and neck cancer patients and corresponding healthy controls matched in age and sex using polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP). In analysis of CYP1A1, the Val/Val genotype of exon 7 polymorphism and m2/m2 genotype of Msp 1 polymorphism were associated with higher relative risks to head and neck cancers (Odds ratio : 2.34, 95% CI : 0.79-6.96 and 1.27, 95% CI : 0.59-2.73, respectively). In combined genotyping of CYP1A1 and GSTMI enzymes polymorphisms, the patients with Val/Val ad GSTM1(-), and m1/m21 and GSTM1(-) combined genotypes had higher relative risks than the patients with each base genotype of combined genotypes (Odds ratio : 4.57, 95% CI : 0.5-41.25 and 1.65, 95% CI L 0.73-3.77, respectively). These results sugget the combined genotyping of metabolizing enzymes could be useful for predicting individual genetic susceptibility and screening the high risk subpopulation to head and neck cancer in Korea.

Model Test of Dual-Buoy Wave Energy Converter using Multi-resonance (다중 공진을 이용한 이중 부이 파력발전장치의 모형실험)

  • Kim, Jeong-Rok;Hyeon, Jong-Wu;Koh, Hyeok-Jun;Kweon, Hyuck-Min;Cho, Il-Hyoung
    • Journal of Ocean Engineering and Technology
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    • v.29 no.2
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    • pp.191-198
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    • 2015
  • In this study, we proposed a new type of dual-buoy wave energy converter (WEC) exploiting multi-resonance and analyzed the experimental results from a model test in a 2-D wave flume. A dual-buoy WEC using multi-resonance has two advantages: high efficiency at the resonant frequencies and the potential to extend the frequency range available to extract wave power from the WEC. The suggested WEC was composed of an outer buoy and an inner buoy sliding vertically inside the outer buoy. As the power take-off device, a linear electric generator (LEG) consisting of permanent magnets and coils fixed at each buoy was adopted. Electricity was produced by the relative heave motion between the two buoys. To search for the optimal shape of a dual-buoy WEC, we conducted experiments on the heave motion of a two-body system in regular waves without an LEG installed. Model tests with six combinations of experimental models were conducted in order to find the motion characteristics of a dual-buoy WEC. It was found that model 2, which included a ring-shaped appendage to move the resonant frequency of the outer buoy toward a high value, showed a higher relative heave response amplitude operator (RAO) curve than model 1. In addition, the double-peak shape of the heave RAO curve shown for model 2 indicated the extension of the frequency range for extracting wave power in irregular waves.

Comparison of the oral microbial composition between healthy individuals and periodontitis patients in different oral sampling sites using 16S metagenome profiling

  • Kim, Yeon-Tae;Jeong, Jinuk;Mun, Seyoung;Yun, Kyeongeui;Han, Kyudong;Jeong, Seong-Nyum
    • Journal of Periodontal and Implant Science
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    • v.52 no.5
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    • pp.394-410
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    • 2022
  • Purpose: The purpose of this study was to compare the microbial composition of 3 types of oral samples through 16S metagenomic sequencing to determine how to resolve some sampling issues that occur during the collection of sub-gingival plaque samples. Methods: In total, 20 subjects were recruited. In both the healthy and periodontitis groups, samples of saliva and supra-gingival plaque were collected. Additionally, in the periodontitis group, sub-gingival plaque samples were collected from the deepest periodontal pocket. After DNA extraction from each sample, polymerase chain reaction amplification was performed on the V3-V4 hypervariable region on the 16S rRNA gene, followed by metagenomic sequencing and a bioinformatics analysis. Results: When comparing the healthy and periodontitis groups in terms of alpha-diversity, the saliva samples demonstrated much more substantial differences in bacterial diversity than the supra-gingival plaque samples. Moreover, in a comparison between the samples in the case group, the diversity score of the saliva samples was higher than that of the supra-gingival plaque samples, and it was similar to that of the sub-gingival plaque samples. In the beta-diversity analysis, the sub-gingival plaque samples exhibited a clustering pattern similar to that of the periodontitis group. Bacterial relative abundance analysis at the species level indicated lower relative frequencies of bacteria in the healthy group than in the periodontitis group. A statistically significant difference in frequency was observed in the saliva samples for specific pathogenic species (Porphyromonas gingivalis, Treponema denticola, and Prevotella intermedia). The saliva samples exhibited a similar relative richness of bacterial communities to that of sub-gingival plaque samples. Conclusions: In this 16S oral microbiome study, we confirmed that saliva samples had a microbial composition that was more similar to that of sub-gingival plaque samples than to that of supra-gingival plaque samples within the periodontitis group.