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Study on the Fabrication of Ceramic Core using a Gel-casting Process in Aqueous medium(I) : Gelation Behavior of Polydispered Ceramic Slip (수용액 매체에서 젤-케스팅 공정을 이용한 세라믹 코어 제조에 관한 연구(I) : 다성분계 분산 세라믹 슬립의 젤화 거동)

  • Kim, Jae-Won;Kim, Du-Hyeon;Kim, In-Su;Yu, Yeong-Su;Kim, Jae-Cheol;Jo, Chang-Yong
    • Korean Journal of Materials Research
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    • v.11 no.2
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    • pp.137-145
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    • 2001
  • A new process, gelcasting in aqueous medium, to fabricate complex-shaped ceramic core has investigated. The ceramic slurry, mixture of fused silica powder and additives such as zircon and cordierite, was electrosterically stabilizes. The slip was prepared by ball milling of polydispered ceramic suspension with monomer, dimer and dispersant. The rheological behavior of slip was evaluated by viscosity measurement. It was found that the high solid loading of polydispersed ceramic slip, which has low viscosity of 50vol%, is possible to obtained. The viscosity of the slip was significantly dependent upon the amount of polymer dispersant and the formulation of monomer and dimer. The green bodies were fabricated through casting and gelation at room temperature followed by drying at $25^{\circ}C$ for 48hrs under relative humidity of 80~85%. Crack-free green body was successfully fabricated through the above process.

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A Study on the Electrochemical Behavior of Au and Pd in Hydrochloric Acidic Solution (염산 수용액 중에서 Au와 Pd의 전기화학적 거동에 관한 연구)

  • Yu, Yeon-Tae;Kim, Chi-Kwon
    • Korean Journal of Materials Research
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    • v.11 no.2
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    • pp.76-81
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    • 2001
  • In order to recover Au and Pd from the leaching solution of various electronic wastes by electrowinning, the electrochemical behavior of Au and Pd in hydorchloric acidic solution was investigated by means of voltammetry. The reduction potential of Au ion was 800mV and the limiting current appeared at 470mV in electrolytic solution of gold. The reduction potential of Pd ion was 500mv and the limiting current appeared at 150mV in electrolytic solution of Palladium. However, in Au-Pd electrolytic solution, the Potentials for reduction and the limiting current of Au decreased as the content of Pd in electrolyte increased, and the potentials for the limiting current of Au and Pd closed nearest together when percentage of Pd electrolytic solution was 37v71% in Au-Pd electrolyte.

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The Effect of Aerobic Exercise and CWT on Cardiorespiratory Function and Body Composition For Female Workers (유산소운동과 Circuit Weight Training이 직장여성의 호흡순환기능 및 신체조성에 미치는 영향)

  • Lee, Jae-Gue
    • Journal of Life Science
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    • v.13 no.4
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    • pp.448-456
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    • 2003
  • The purpose of this study was to determine changes in their cardiorespiratory function and body composition in female workers after aerobic exercise and circuit weight training. The subjects of this study were 16 female workers in B city and was divided into exercise and control groups which were composed of 8 people respectively. The members of exercise group had aerobic exercise and circuit weight training an hour a day, 5 days per week, for 8 weeks while controled group did not. Both groups were pretested and posttested, and the results of this study on cardiorespriatory function and body composition are as follows. Exercise group showed significant decrease in heart rate at rest(p<.001). Exercise group showed significant increase in the oxygen uptake at rest, in the maximum oxygen uptake and in the vital capacity(p<.001). Exercise group showed significant decrease in the %fat and fat(p<.001). Exercise group showed significant increase in the %LBM and LBM(p<.001).

Topology-Based Flow-Oriented Adaptive Network Coding-Aware Routing Scheme for VANETs

  • Iqbal, Muhammad Azhar;Dai, Bin;Islam, Muhammad Arshad;Aleem, Muhammad;Vo, Nguyen-Son
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.5
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    • pp.2044-2062
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    • 2018
  • Information theory progression along with the advancements being made in the field of Vehicular Ad hoc NETworks (VANETs) supports the use of coding-aware opportunistic routing for efficient data forwarding. In this work, we propose and investigate an adaptive coding-aware routing scheme in a specific VANET scenario known as a vehicular platoon. Availability of coding opportunities may vary with time and therefore, the accurate identification of available coding opportunities at a specific time is a quite challenging task in the highly dynamic scenario of VANETs. In the proposed approach, while estimating the topology of the network at any time instance, a forwarding vehicle contemplates the composition of multiple unicast data flows to encode the correct data packets that can be decoded successfully at destinations. The results obtained by using OMNeT++ simulator reveal that higher throughput can be achieved with minimum possible packet transmissions through the proposed adaptive coding-aware routing approach. In addition, the proposed adaptive scheme outperforms static transmissions of the encoded packets in terms of coding gain, transmission percentage, and encoded packet transmission. To the best of our knowledge, the use of coding-aware opportunistic routing has not been exploited extensively in available literature with reference to its implications in VANETs.

Influence of Carotene Supplementation on Serum Carotene and Retinol Levels in Lactoovovegetarian and Nonvegetarian Women (카로텐 공급이 정상식이 여성과 채식주의 여성의 혈청 카로텐 및 레티놀 수준에 미치는 영향)

  • 김혜영
    • Journal of Nutrition and Health
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    • v.22 no.4
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    • pp.257-265
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    • 1989
  • Normal healthy non vegetarian and lact$\infty$,vo­v vegetarian women were studied after they con­S sumed carrot juices as supplements. Daily sup­p plementation resulted in significant increase in serum levels of $\alpha$-, $\beta$-carotene and total carote­n noid in nonvegetarians and $\alpha$-and $\beta$-carotene in lactoovovegetarians. Reflection in serum and $\beta$-carotene was higher in nonvegetarians m than lactoovovegetarians. However, serum caro­t tene values were not significantly different between group after continous supplementation of reducing amounts of carotenes. Serm retionol levels were not changed throughout the study period and were not significantly different bet­w ween nonvegetarians and lactooovegetarians. The results suggest that serm total carotenoid cannot bean indicator of individual carotene such as $\alpha$-or $\beta$-carotene in serum and serum carotene levels are closely related to dietary carotene intake both in nonvegetartins and lac­t toovovegetanans

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ON PETERSON'S OPEN PROBLEM AND REPRESENTATIONS OF THE GENERAL LINEAR GROUPS

  • Phuc, Dang Vo
    • Journal of the Korean Mathematical Society
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    • v.58 no.3
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    • pp.643-702
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    • 2021
  • Fix ℤ/2 is the prime field of two elements and write 𝒜2 for the mod 2 Steenrod algebra. Denote by GLd := GL(d, ℤ/2) the general linear group of rank d over ℤ/2 and by ${\mathfrak{P}}_d$ the polynomial algebra ℤ/2[x1, x2, …, xd] as a connected unstable 𝒜2-module on d generators of degree one. We study the Peterson "hit problem" of finding the minimal set of 𝒜2-generators for ${\mathfrak{P}}_d$. Equivalently, we need to determine a basis for the ℤ/2-vector space $$Q{\mathfrak{P}}_d:={\mathbb{Z}}/2{\otimes}_{\mathcal{A}_2}\;{\mathfrak{P}}_d{\sim_=}{\mathfrak{P}}_d/{\mathcal{A}}^+_2{\mathfrak{P}}_d$$ in each degree n ≥ 1. Note that this space is a representation of GLd over ℤ/2. The problem for d = 5 is not yet completely solved, and unknown in general. In this work, we give an explicit solution to the hit problem of five variables in the generic degree n = r(2t - 1) + 2ts with r = d = 5, s = 8 and t an arbitrary non-negative integer. An application of this study to the cases t = 0 and t = 1 shows that the Singer algebraic transfer of rank 5 is an isomorphism in the bidegrees (5, 5 + (13.20 - 5)) and (5, 5 + (13.21 - 5)). Moreover, the result when t ≥ 2 was also discussed. Here, the Singer transfer of rank d is a ℤ/2-algebra homomorphism from GLd-coinvariants of certain subspaces of $Q{\mathfrak{P}}_d$ to the cohomology groups of the Steenrod algebra, $Ext^{d,d+*}_{\mathcal{A}_2}$ (ℤ/2, ℤ/2). It is one of the useful tools for studying these mysterious Ext groups.

Characteristics of Potential Gamma-Aminobutyric Acid-Producing Bacteria Isolated from Korean and Vietnamese Fermented Fish Products

  • Vo, Thi Thu-Thao;Park, Jong-Hyun
    • Journal of Microbiology and Biotechnology
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    • v.29 no.2
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    • pp.209-221
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    • 2019
  • Gamma-aminobutyric acid (GABA) is a neurotransmitter that exerts several physiological functions and positive effects on human health. The aim of this study was to isolate and characterize the strains that had GABA-producing abilities from various fermented fish products. A total of 91 acid-producing strains were isolated from 41 samples of fermented fish products, and 27 strains showing GABA-producing abilities were identified by the 16S rDNA sequences. Among the strains, 31% strains tolerated at high-salt environment of 10-20% throughout the fermentation of fish sauces. The 27 isolates that produced GABA at various concentrations did so in the range of 5 to 454 mM. These GABA-producing isolates were identified as lactic acid bacteria of 14 strains, which included twelve Lactococcus lactis, one Enterococcus faecium, and one Lactococcus pentosus; eight Bacillus cereus group, which included seven B. thuringiensis and one B. cereus; and five Staphylococcus spp. Interestingly, with Vietnamese fish sauces, we mostly identified species of B. thuringiensis and Staphylococcus spp., while with Korean fermented fish products, the majority of the strains identified belonged to L. lactis. Among the strains, B. thuringiensis LH2134 produced the highest levels of GABA at 366 mM among the strains identified from Vietnamese fish sauces, whereas L. lactis LA43, a new strain isolated from Korean jeotgal (salted shrimp paste), produced the highest amount of GABA at 454 mM and the glutamate concentration in the medium was essential for GABA accumulation. Therefore, such the isolates might serve as good starters for development of more GABA-reinforced foods among fermented fish products.

Key Determinants for Users Intention to Use Smarthome Devices in Vietnam

  • Nguyen, Thi-Hong-Linh;Duong, Minh-Hung;Nguyen, Hai-Dang;Vo, Dang-HongNgan;Vu, Duy-Phuong-Trinh;Le, Hoanh-Su
    • Journal of Multimedia Information System
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    • v.5 no.4
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    • pp.283-290
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    • 2018
  • Smarthome is one of the remarkable fields of the industrial revolution 4.0, which are popular in many countries such USA, EURO, Japan and Korea. However, how Vietnamese people are considering and having intension to use smarthome devices is still a question for marketers and researchers. This study develops a comprehensive research model that can explain potential customers' behavioral intentions to adopt and use Smarthome services in Viet Nam and figure which key factors affect the intention. This study proposes and validates a new theoretical model that extends the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2). The model consists of eight factors that affect one element (Behavioral Intention), specifically: Habits, Perceived usefulness, Perceived ease of use, Trust, Innovativeness Personal, Perceived value, Hedonic motivations and Social influences. Data were collected from 304 Vietnamese citizens by sending the email to survey questionnaire, direct contact with the experienced smarthome users. Through regression analysis, data from samples were analysed with SPSS 20 software and verification of hypotheses, the results show the key determinants affecting the intention to use smarthome appliances in Vietnam: Perceived Value, Social Influence, Perceived Usefulness, Perceived Ease of Use and Trust. From this result, several recommendations have been suggested to to smarthome devices vendors and marketer to improve products as well as marketing approaches to meet customer needs.

Production Regimes, Family Policy and Gender Wage Gap (생산레짐과 일가정양립정책이 성별 임금격차에 미치는 영향연구)

  • Kang, Ji Young
    • Korean Journal of Social Welfare Studies
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    • v.48 no.3
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    • pp.145-169
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    • 2017
  • Female plays an important role in new welfare policies as emerging new social risks including care needs resulted from increasing female employment participation and changes in family structures. Whereas the effects of work and life reconciliation policies on female employment are well established, less is known for the role of production regime as an important institution on gender wage gap. This study examines the questions in what way and to what extent production regimes and work and family reconciliation policies influence gender wage gap in advanced capitalism countries using the Luxembourg Income Study (LIS). The coordinated market economies (CMEs), presented as higher firm-specific skills, are associated with lower income rank for female workers than male workers, hence larger degree of gender wage gap. Longer parental leave weeks and higher childcare expenditures are associated with less degree of gender wage gap. This research highlights the importance of production regimes in understanding gender wage gap and potential interaction between production regimes and work and life reconciliation policies on gender wage gap.

A Meta-analysis for the Effects of Exercise on Pulmonary Function in Patients with Ankylosing Spondylitis (강직성 척추염 환자의 폐기능에 미치는 운동효과에 대한 메타분석)

  • Kim, Eun-Jeong;Lee, Eun-Nam;Yu, Eun-Jeong
    • Journal of muscle and joint health
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    • v.26 no.2
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    • pp.141-154
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    • 2019
  • Purpose: This study aimed to analyze the effects of exercise on pulmonary function in patients with ankylosing spondylitis (AS). Methods: Randomized controlled trials (RCTs) were identified by searching MEDLINE, EMBASE, CENTRAL, and CINAHL (through Jan 2019). Three reviewers independently retrieved articles, extracted data, and assessed methodological quality using the Cochrane's Risk of Bias for randomized studies. Results: Fourteen studies met the inclusion criteria with a total of 729 participants. CE (SMD 0.58, 95% CI 0.41~0.75, p<.001) and $VO_2peak$ (SMD 0.56, 95% CI 0.24~0.88, p=.001) had a significant effect on the most exercise interventions. As a secondary variable, BASFI (SMD -0.53, 95% CI -0.70~-0.37, p<.001), BASMI (SMD -0.75, 95% CI -0.92~-0.58, p<.001) showed an effect size of more than medium. However, PFT and QoL did not produce a significant results. Conclusion: Pulmonary involvement is common in patients with AS and might have disturbed functionality and exercise modality. Exercise can be an effective intervention to improve pulmonary function in patients with AS. More attention is needed to improve the chest and spinal mobility to maintain the appropriate pulmonary function. It is also necessary to consider how to construct a patient-tailored exercise program to increase performance, accuracy and safety of exercise.