• Title/Summary/Keyword: stress reduce

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The Estimation of Friction Velocity in an Open Channel by the Entropy Concept (엔트로피 개념을 활용한 개수로 마찰속도 산정)

  • Choo, Tai Ho;Son, Hee Sam;Yun, Gwan Seon;Noh, Hyun Seok;Ko, Hyun Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.2
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    • pp.1533-1540
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    • 2015
  • In order to demonstrate the flow properties of the river bed and the design of hydraulic structures, the estimation of friction velocity is essentially required. However, existing friction velocity equations such as Log method and Power law have trouble to estimate the friction velocity because a boundary condition and various hydraulic properties are changed constantly in near the wall. In the present study, therefore, a new friction velocity equation that can minimize the parameters and reduce an error was suggested. To verify accuracy and reliability for the proposed equation, Clauser method, $\sqrt{gRI}$ method, reynolds stress method by Dr. Song were compared with the proposed method by estimated entropy parameter M for each channel. Consequently, the results show that uniform flow condition as well as non-uniform flow condition with highly accuracy nearly matched in case of accelerating non-uniform condition of $R^2=0.9621$, Decelerating Non Uniform condition of $R^2=0.9274$, Uniform condition of $R^2=0.8865$.

Probabilistic Service Life Analysis of GGBFS Concrete Exposed to Carbonation Cold Joint and Loading Conditions (탄산화에 노출된 GGBFS 콘크리트의 콜드 조인트 및 하중 재하를 고려한 확률론적 내구수명 해석)

  • Kim, Tae-Hoon;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.3
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    • pp.39-46
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    • 2020
  • Carbonation is a deterioration which degrades structural and material performance by permitting CO2 and corrosion of embedded steel. Service life evaluation through deterministic method is conventional, however the researches with probabilistic approach on service life considering loading and cold joint effect on carbonation have been performed very limitedly. In this study, probabilistic service life evaluation was carried out through MCS (Monte Carlo Simulation) which adopted random variables such as cover depth, CO2 diffusion coefficient, exterior CO2 concentration, and internal carbonatable materials. Probabilistic service life was derived by changing mean value and COV (Coefficient of variation) from 100 % to 300 % and 0.1 ~ 0.2, respectively. From the analysis, maximum reduction ratio (47.7%) and minimum reduction ratio (11.4%) of service life were obtained in cover depth and diffusion coefficient, respectively. In the loading conditions of 30~60% for compressive and tensile stress, GGBFS concrete was effective to reduce cold joint effect on carbonation. In the tensile condition, service life decreased linearly regardless of material types. Additionally service life rapidly decreased due to micro crack propagation in the all cases when 60% loading was considered in compressive condition.

Protective Effects of Akebia quinata Fruit Extract on Acute Alcohol-induced Hepatotoxicity in Mice (급성 알코올 간독성을 유발한 생쥐에 있어서 으름 열매 추출물의 간 기능 보호효과)

  • Lee, Sang Hoon;Song, Young Sun;Lee, Seo Yeon;Kim, So Young;Ko, Kwang Suk
    • Korean Journal of Food Science and Technology
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    • v.46 no.5
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    • pp.622-629
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    • 2014
  • We studied the effects of Akebia quinata fruit extract (AQ) on acute alcohol-induced hepatotoxicity in mice. AQ (30-1,000 mg/kg body weight (BW) per day) was orally administered to the study group, once daily for 1 week. On the last day of AQ treatment, ethanol (6 mg/kg BW) was orally administered to induce acute liver injury. The AQ-treated group showed significantly lower levels of alanine aminotransferase and aspartate aminotransferase, compared to the only ethanol-treated group (ETG). The glutathione level in the AQ-treated group elevated up to 20.6%, compared to that observed in the ETG. The mRNA expression of glutathione synthetic enzymes was also higher in the AQ-treated group, compared to the ETG. The AQ-treated group also exhibited lower levels of expression of NADPH oxidase 4 and tumor necrosis factor alpha mRNA. Thus, these results show that AQ treatment can be a potential method to reduce oxidative stress and inflammation in ethanol-treated mouse liver and also that AQ can be a useful therapeutic agent for acute alcohol-induced hepatotoxicity.

The Effects of the Stroke on the Health Knowledge, Optimistic Bias and Health-Promoting Lifestyle in Middle-Aged Adults (중년기 성인의 뇌졸중 관련 건강지식, 낙관적 편견이 건강증진 생활양식에 미치는 효과)

  • Jeong, Young-Ju;Park, Jin-Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.9
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    • pp.141-155
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    • 2016
  • This research is a descriptive study that aimed to identify the health knowledge and optimistic bias related to stroke of middle-aged adults and the effect these had on their health-promoting lifestyle. The research was conducted from July 15 to August 15, 2015. The research subjects were 191 adults aged between 40 to 60 years. A structured questionnaire was used and self-administered for data collection. The PASW Statistics 21.0 and AMOS 21.0 programs were used for data analysis, and analysis of variance, correlation analysis, and structural equation modeling analysis were conducted. It was found that the middle-aged adults recognized smoking and hypertension as higher risk factors for stroke than diabetes, and there was a slight optimistic bias for stroke. Health knowledge about stroke had correlations with optimistic bias (r = -.143, p = .048) and health-promoting lifestyle (r = .268, p = < .001), while optimistic bias had correlations with interpersonal relationships and stress (r = .177, p = .014) in health-promoting lifestyle. In addition, health-promoting lifestyle affected health knowledge more than optimistic bias. In conclusion, it was found that the active information acquisition, health knowledge, and optimistic bias of middle-aged adults toward stroke were important factors pertaining to a stroke-related health-promoting lifestyle. Therefore, an education program to improve the health-promoting lifestyle related to stroke in middle-aged adults should be considered as a way to enhance stroke-related health knowledge and reduce optimistic bias.

Determined Car Door Latch Injection Molding Process Conditions through the Finite Elements Analysis (유한요소 해석을 통한 차량용 도어 래치 사출성형 공정조건 결정)

  • Lee, Jung-Hyun;Lee, Seon-Bong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.10
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    • pp.499-508
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    • 2016
  • Injection molding is a method for manufacturing many products, wherein a plasticized resin is injected into a mold at high pressure and hardened. According to the method, the product can be manufactured into various forms, and the mass production of up to tens of thousands of products is possible. The purpose of this study was to determine the process conditions for manufacturing a door latch for automobiles, through an analysis of the injection molding method. To calculate an appropriate injection flow for injection molding, a primary analysis for comparing the injection time, pressure, flow pattern, consolidation range, shear stress, shear rate, and weld line, as well as a secondary analysis for determining the conditions for stabilizing the molding temperature, holding pressure, and cooling process, were conducted. The characteristics of injection molding, and their influence on the product quality are discussed. No weld line and pores were observed on the products that had been manufactured based on the process conditions determined above. In addition, there were no flaws regarding the deformation compared to the prototype. Therefore, the manufacture of a product under the conditions determined in this study can reduce the defect rate compared to the existing production, and the process is also more competitive due to reduced production time.

Effects of Oleanolic Acid and Hederagenin on Acute Alcohol-Induced Hepatotoxicity in Mice (마우스에서 Oleanolic Acid와 Hederagenin이 급성 알코올성 간독성에 미치는 효과)

  • Jung, Suhan;Lee, Sanghoon;Ko, Kwang Suk
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.45 no.3
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    • pp.307-312
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    • 2016
  • We studied the effects of oleanolic acid and hederagenin on acute alcohol-induced hepatotoxicity in mice. Oleanolic acid [10 and 20 mg/kg body weight (BW)/d] or hederagenin (10 and 20 mg/kg BW/d) was orally administered to the study group for 1 week. On the last day of treatment, ethanol (5 g/kg BW) was orally administered to induce acute liver injury. The oleanolic acid-treated group showed lower levels of alanine aminotransferase compared to the ethanol-treated group (EtOH). The mRNA expression level of alcohol dehydrogenase was significantly increased in the high dosage oleanolic acid-treated group compared with the control and EtOH groups. The glutathione levels of the oleanolic acid or hederagenin-treated groups were elevated significantly compared with those of the control and EtOH groups. The mRNA expression levels of glutathione synthetic enzymes were also elevated in the oleanolic acid-treated groups. The oleanolic acid or hederagenin-treated groups also showed lower levels of mRNA expression of tumor necrosis factor alpha. Thus, these results show that oleanolic acid and hederagenin could reduce oxidative stress and hepatotoxicity in ethanol-treated mouse liver.

Anti-oxidative capacity of mulberry genetic resources (뽕나무 유전자원의 항산화능 비교)

  • Kim, Hyun-bok;Seok, Young-Seek;Seo, Sang-Deok;Sung, Gyoo Byung;Kim, Sung-Kuk;Jo, You-Young;Kweon, HaeYong;Lee, Kwang-Gill
    • Journal of Sericultural and Entomological Science
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    • v.53 no.2
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    • pp.71-77
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    • 2015
  • Much attention has been focused on the activity of the natural antioxidants present in fruits and vegetables, because potentially these components may reduce the level of oxidative stress. Especially, mulberry leaves containing many natural components are considerable resource for natural antioxidants. The antioxidant capacity of mulberry leaves was investigated with minilum L-100 device and ARAW-KIT (anti-radical ability of water-soluble substance), in comparison to the ascorbic acid. The antioxidant capacity of 16 varieties was 3303.4 nmol at opening stage of five leaves in spring. The highest stage of antioxidant capacity (3708.0 nmol) and yield rate was just before the coloration stage with anthocyanin in fruits, whereas the lowest stage was middle of June (2231.6 nmol) and about two months growing stage after summer pruning (2064.6 nmol). But after summer pruning, the antioxidant capacity of mulberry leaves increased gradually until just before fallen leaves stage. Even if samples were same variety, antioxidant effect of those showed different results according to collected regions. Also, antioxidant effect of mulberry leaves were higher than that of branches. The antioxidant capacity of yield-type mulberry leaves and fruits (Morus alba L., M. bombycis Koidz, and M. Lhou (Ser.) Koidz) collected from In-je, Won-ju and Yang-yang regions, Kang-won province, Korea, was investigated. The results indicated that total antioxidant capacity of yield-type mulberry leaves was 2711.2 nmol. In the antioxidant capacity analysis of Jeollabuk-Do genetic resources, autumn's mulberry leaves showed higher antioxidant capacity than that of spring's it. To investigate the effect of tea on antioxidative capacity, five kinds of tea(coffee mix, green tea added brown rice, mulberry leaf tea, Polygonatum odoratum tea and black tea added lemon) were selected and analyzed. Their's anti-oxidative capacity were 2,531.01 nmol, 1,867.42 nmol, 1,053.72 nmol, 292.71 nmol and 188.91 nmol, respectively. The antioxidative capacity of drinking water soaked with mulberry leaf showed 891.96 nmol.

The Rheology of Cement Paste Using Polycarboxylate-Based Superplasticizer for Normal Strength-High Fluidity Concrete (보통강도 고유동 콘크리트용 PC계 고성능 감수제를 사용한 시멘트 페이스트의 레올로지 특성 평가)

  • Kong, Tae-Woong;Lee, Han-Seung
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.3
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    • pp.276-286
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    • 2021
  • General high fluidity concrete is the area of high strength concrete with a high amount of cement to secure the required fluidity and workability. Since most of the concrete structures currently used have normal strength, there is a limit to the practical expansion and practicality of use. Thus it is necessary to develop normal strength-high fluidity concrete with low binders that can be used not only in general buildings but also in special buildings, and can greatly reduce construction time and save labor costs. This requires to develop and apply the polycarboxylate-based superplasticizer. In this study, PCE was prepared for each combination of starting materials(WR, HB, RT) and the rheological properties of cement paste were analyzed using ringflow cone and a rotary viscometer. As a result, when PCE with a combination of WR 80%, HB 6.5%, and RT 13.5% was applied, the yield stress can be minimized while securing the plastic viscosity at level of the normal strength. In addition, high fluidity due to the high dispersion effect was confirmed.

Effects of photoperiod and light intensity on milk production and milk composition of dairy cows in automatic milking system

  • Lim, Dong-Hyun;Kim, Tae-Il;Park, Sung-Min;Ki, Kwang-Seok;Kim, Younghoon
    • Journal of Animal Science and Technology
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    • v.63 no.3
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    • pp.626-639
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    • 2021
  • The purpose of this study was to determine the effects of photoperiod and light intensity on milk production, milk composition, hormones levels and blood metabolites indices of Korean Holstein dairy cows in automatic milking system (AMS). A total of 24 Holstein dairy cows were selected and used to four subsequent treatments for the experimental periods of 60 days. The light programs consisted of (1) Control: the natural photoperiod with 14.2 h of the light period and 9.4 h of the dark period (below 10 Lux); (2) T1: 16 h of the long day photoperiod (LDPP) with 50 Lux of light; (3) T2: 16 h of LDPP with 100 Lux of light; and (4) T3: 16 h of LDPP with 200 Lux of light, respectively. Importantly, there was a significant difference in the thurl activity of dairy cows between the different light intensity programs (p < 0.05). Milk yield was higher in T1 and T2 (40.80 ± 1.71 and 39.90 ± 2.02 kg/d, respectively) than those of Control and T3 (32.18 ± 1.51 and 35.76 ± 2.80 kg/d, respectively) (p < 0.05), but DMI was lower in T1, T2, and T3 compared to Control (p < 0.05). Also, milk fat percentage, the contents of milk fat and total solids were higher in T2 than those in the others (p < 0.05). The average daily melatonin level in milk was high to T3 (28.20 ± 0.43 pg/mL), T2 (24.62 ± 0.32 pg/mL), T1 (19.78 ± 0.35 pg/mL), and Control (19.36 ± 0.45 pg/mL) in order (p < 0.05). Also, the cortisol levels in milk and blood were lower in treatment groups than in Control (p < 0.05). The results of this study showed that it will be effective to improve the milk yield and milk composition, and to reduce the stress of dairy cows when the light conditions regulate to extend the photoperiod to 16 h at a light emitting diode (LED) intensity of 100 Lux under the AMS in dairy farm.

Destructive and Non-destructive Tests of Bamboo Oriented Strand Board under Various Shelling Ratios and Resin Contents

  • Maulana, Sena;Gumelar, Yuarsa;Fatrawana, Adesna;Maulana, Muhammad Iqbal;Hidayat, Wahyu;Sumardi, Ihak;Wistara, Nyoman Jaya;Lee, Seung Hwan;Kim, Nam Hun;Febrianto, Fauzi
    • Journal of the Korean Wood Science and Technology
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    • v.47 no.4
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    • pp.519-532
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    • 2019
  • The objectives of this study were to evaluate the effects of shelling ratio and resin content on the properties of bamboo oriented strand board (BOSB) from betung (Dendrocalamus asper) and to determine the correlation between the results of dynamic and static bending tests. Strands were steam-treated at $126^{\circ}C$ for 1 h under 0.14 MPa pressure and followed by washing with 1% NaOH solution. Three-layer BOSB with the core layer perpendicular to the surface was formed with shelling ratios (face:core ratio) of 30:70; 40:60; 50:50; 60:40 and binded with 7% and 8% of phenol formaldehyde (PF) resin with the addition of 1% of wax. The evaluation of physical and mechanical properties of BOSB was conducted in accordance with the JIS A 5908:2003 standard and the results were compared with CSA 0437.0 standard for commercial OSB (Grade O-1). Non-destructive testing was conducted using Metriguard Model 239A Stress Wave Timer which has a wave propagation time from 1 to $9,999{\mu}s$ and a resolution of $1{\mu}s$. BOSB with 8% resin content showed better physical and mechanical properties than those with 7% resin content. The increase of the face layer ratio improved the strength of BOSB in parallel direction to the grain. The results suggested that shelling ratio of 50:50 could be used as a simple way to reduce PF resin requirements from 8% to 7% and to meet the requirements of CSA 0437.0 standard. The results of non-destructive and destructive tests showed a strong correlation, suggesting that non-destructive test can be used to estimate the bending properties of BOSB.