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Nonlinear Analysis of CFT Truss Girder with the Arch-shaped Lower Chord (아치형상의 하현재를 갖는 CFT 트러스 거더의 재료 비선형 해석)

  • Song, Na-Young;Choung, Chul-Hun;Kim, Young-Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.6A
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    • pp.625-639
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    • 2009
  • Experimental and analytical studies are performed on the mechanical behavior of concrete-filled tubular(CFT) truss girders for different f/L ratios. Bending tests are conducted on two CFT truss girder specimens to determine fundamental structural characteristics such as the strength and deformation properties. Nonlinear material models for CFT members subjected to an axial compressive force are compared in this paper by using the nonlinear finite element program, ABAQUS. Previous researchers have proposed several nonlinear stress-strain models of confined concrete. In this study, the nonlinear analyses are performed applying several stress-strain models for confined concrete proposed by Mander, Sakino, Han, Susantha and Ellobody, and the results are compared with the experimental results in terms of load-deflection and load-strain relationships. Based on the comparisons of the load-deflection relationships, the models proposed by Mander and Susantha provide a maximum load about 12.0~13.8% higher and that by Sakino gives a maximum load about 7.6% higher than the experimental results. The models proposed by Han and Ellobody give a maximum load only about 0.2~1.2% higher than the test results, showing the best agreement among the proposed stress-strain models. However, the load-strain relations predicted by the existing models generally provide conservative results exhibiting larger strains than the experimental data.

Wastewater Treatment by using a Rotating Photocatalitic Oxidation Disk System (회전광촉매 시스템에 의한 폐수처리)

  • Chung, Ho Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.5B
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    • pp.497-502
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    • 2009
  • The wastewater treatment by photocatalyst decomposes pollutants directly in water, and it is easy to decompose indecomposable organics and inorganic. and Especially, it has an advantage that there is no secondary production of pollutants. However, there will be many problems which are generated depending on the type of photocatalyst. The type of rotating photocatalyst minimizes previous problems, and advanced oxidation processes is possible by the application of rotating disc method. The consideration of the characteristics about various designs and operation factors is needed for the application of rotating photocatalyst system. In this study, rotating photocatalyst was manufactured for rotating disc method by fixing of $TiO_2$. The operation factors were derived for the wastewater treatment by the reaction of rotating photocatalyst. The contained quantity of $TiO_2$ was limited about 70%. The more the contained quantity of $TiO_2$ was increased, the more the treatment rate was continually increased. The optimum rotating photocatalyst was R4, and the contained quantity of $TiO_2$ was 36.8%. The more the exposed amount of UV is increased, the more the decomposition effect of TCODcr was continually increased. However, the adequate strength of light source must be determined by the consideration of economical efficiency. The more the speed of rotating photocatalyst is increased, the more treatment efficiency was increased. When UV lamp was not submerged in reactor, the wastewater treatment was efficient in the order of the depth of water 50%, 30%, 10%, 70%, 100%. This study is a basic research for the development of a system which treats organics in solar light.

Analysis of Reinforcement Effect of Steel-Concrete Composite Piles by Numerical Analysis (II) - Bearing Capacity - (수치해석을 이용한 강관합성말뚝의 보강효과 분석 (II) - 지반 지지력 -)

  • Kim, Sung-Ryul;Lee, Si-Hoon;Chung, Moonkyung;Lee, Juhyung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.6C
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    • pp.267-275
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    • 2009
  • The steel pipe of steel-concrete composite piles increases the pile strength and induces the ductile failure by constraining the deformation of the inner concrete. In this research, the load-movement relations and the reinforcement effect by the outer steel pipe in the steel-concrete composite pile were analyzed by performing three-dimensional numerical analyses, which can simulate the yielding behavior of the pile material and the elasto-plastic behavior of soils. The parameters analyzed in the study include three pile materials of steel, concrete and composite, pile diameter and loading direction. As the results, the axial capacity of the composite pile was 1.9 times larger than that of the steel pipe pile and similar with that of the concrete pile. At the allowable movement criteria, the horizontal capacity of the composite pile was 1.46 times larger than that of the steel pile and 1.25 times larger than that of the concrete pile. In addition, the horizontal movement at the pile head of the composite pile was about 78% of that of the steel pile and about 53% of that of the concrete pile, which showed that the movement reduction effect of the composite pile was significant and enables the economical design of drilled shafts.

Study on Optimum Design for Embankment Construction on Soft Ground Treated by SCP (SCP개량지반상에 성토시공 시 최적설계에 관한 연구)

  • Chae, Jong-gil;Park, Yeong-Mog;Jung, MinSu
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.6C
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    • pp.251-258
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    • 2009
  • In this study, the optimum design conditions for embankment construction on soft clay layer improved by soil compaction pile (SCP) are discussed by comparing the practical design method to the reliability design which is based on the loss function and advanced first order second moment (AFOSM) method. The results are summarized as follows; 1) the relationship between safety factor and failure probability becomes heavy exponentially, failure probability decreases rapidly till 1% approximately until safety factor is smaller than 1.2 and after then, failure probability decrease gradually along the increase of the safety factor. The design safety factor of 1.2 may be the critical value that has been established on considering both relationships appropriately, 2) the safety factor of 1.15 at the minimum expected total cost is a little smaller than the design safety factor of 1.2 and the failure probability is about 1%, 3) the sensitivities of the ratio of stress share and the internal friction angle of sand is larger than the variables related the undrained shear strength of soft layer. This result means that the distribution characteristic of n and ${\phi}$ influences on the stability analysis considerably and they should be considered necessarily on stability analysis of embankment on soft layer improved by SCP, 4) new failure points of the input variables at the design safety factor of 1.2(below failure probability of 0.1~0.3%) is far 1~2 times of standard deviation from the initial design values of themselves.

Response Analysis of Nearby Structures with the Consideration of Tunnel Construction and Ground Conditions (터널시공 및 지반조건을 반영한 인접구조물의 거동분석)

  • Son, Moorak;Yun, Jongcheol
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.6C
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    • pp.255-263
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    • 2010
  • This paper investigates the effects of tunnelling-induced ground movements on nearby structures, considering soil-structure interactions of different construction (ground loss) and soil characteristics. The response of four-story block structures, which are subjected to tunnelling-induced ground movements, has been investigated in different construction (ground loss) and soil conditions using numerical analysis. The structures for numerical analysis has been modelled using Discrete Element Method (DEM) to have real cracks when the shear and tensile stress exceed the maximum shear and tensile strength. The response of four-story block structures has been investigated with a ground movement magnitude and compared in terms of construction (ground loss) and soil conditions considering the magnitude of deformations and cracks in structures. In addition, the damage levels, which are possibly induced in structures, has been provided in terms of construction (ground loss) and soil conditions using the state of strain damage estimation criterion (Son and Cording, 2005). The results of this study will provide a background for better understandings for controlling and minimizing building damage on nearby structures due to tunnelling-induced ground movements.

Impact of concurrent inspiratory muscle and aerobic exercise training on pulmonary function and cardiopulmonary responses (흡기근육 훈련과 유산소운동의 동시적용이 심폐반응과 폐기능에 미치는 영향)

  • Jung, H.J.;Lee, D.T.
    • Exercise Science
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    • v.21 no.3
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    • pp.373-384
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    • 2012
  • The effects of inspiratory muscle training in conjunction with aerobic exercise on inspiratory muscle strength, pulmonary function, and maximal oxygen uptake(VO2max) were examined. Twenty four healthy collegiate men were divided into three groups; respiratory muscle training group(RTG; n=8), running exercise group(REG; n=8), and both respiratory muscle training and running group(BTG; n=8). Their pulmonary function, maximal inspiratory pressures(PImax), and VO2max were assessed before and after intervention. RTG underwent inspiratory muscle training(IMT) with load set to 50 % of PImax, 30 times per session, twice a day, 4 days a week REG ran on a treadmill at 70-75 % of VO2max for 30 min a day, 4 days a week. BTG participated both IMT and the running exercise. Participant's anthropometric parameters and pulmonary function were not changed. VO2max increased by 6.1±3.3 %, 5.9±6.6 %, and 10.0±8.3 % in RTG, REG, and BTG, respectively(p< .05), and PImax also increased by 21.7±14.3 %, 19.7±12.0 %, and 27.0±12.1 % in RTG, REG, and BTG, respectively, but no group differences were found. Based on the study, although statistically insignificant, BTG showed the biggest increase of VO2max and PImax indicating a possible synergic effect of inspiratory muscle training and aerobic exercise on respiratory responses.

Comparison between South Korean and Taiwanese college culture: Focusing on the Hierarchical Sexist Influence of Military Culture (한국과 대만의 대학문화 비교 : 위계와 성차별, 폭력의 군대적 징후를 중심으로)

  • Kwon, Insook;Nah, Yoonkyeong;Moon, Hyona
    • Women's Studies Review
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    • v.27 no.1
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    • pp.145-183
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    • 2010
  • This study has compared South Korea with Taiwan, a society which has an almost non-hierarchical college culture in spite of its social and historical similarities to Korea, including the recruit system. By the means of quantitative and qualitative comparative studies and analysis, it has tried to clarify the reasons behind the hierarchical and sexist military culture of Korean universities. According to the comparative studies, Taiwan's college culture is less hierarchical than that of South Korea, and support for the necessity of hierarchy is weaker. Hierarchy had a greater influence on the payment of meals, appellations and society admissions in South Korea. Elements of military culture such as violence or group discipline were usually only present in South Korean college culture. Male-centered drinking and prostitution culture was also found to be stronger in South Korea. The historical and social reason for these differences is that Taiwan has a weaker basis for nationalism and militarism, both essential factors in the founding of hierarchical and collective culture. The most direct reason for the lack of hierarchy in Taiwanese college culture is the period of recruitment. In South Korea, young men usually apply for military service during the first or second year or college, and return to school as second or third-year studies. In Taiwan, however, men are usually recruited after having graduated from college. Students who have served in the army have proved to have a significant influence on violence, hierarchy and drinking culture in Korea's college culture. South Korea's college culture has two main problems. The first is that South Korean college students are not able to be critical towards the harms of South Korea's oppressively hierarchical collective culture, and therefore do not develop the strength to fight against it. This is all the more problematic because they are the future components of South Korea's main institutions. The second is that it roots male-centeredness even further into the South Korean mentality.

Development of community-based intensive health care program for the community dwelling elderly (재가노인을 위한 지역사회 중심의 집중건강관리프로그램의 개발과 적용)

  • Song, Mi-Sook;Song, Hyun Jong
    • 한국노년학
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    • v.29 no.1
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    • pp.37-50
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    • 2009
  • The purpose of the present study was to develop a community-based intensive health care program for the community dwelling elderly to strength their functional status and to verify the effect on their geriatric syndrome. A one-group pretest-posttest design was used for the study. A total of 69 frail elderly, who lived in the area within 20 minutes by car, were committed themselves to the day care center(Sangikjae), and had the ability of verbal communication were selected from G city in Kyunggi province. The participants completed a set of questionnaires to measure the sub-score of frailty, fall, urinary incontinence, malnutrition, and mild cognitive disorder domain, using the Otasha-Kensin through the physical examinations and interviews. After 4 weeks of intervention, the outcome was measured to evaluate the effects of the program, and the data obtained were analyzed using descriptive statistics, paired t-test and McNemar test. The results showed that the sub-score of frailty, fall, urinary incontinence, and malnutrition domain were statistically significantly decreased after intervention except those of urinary incontinence and mild cognitive disorder domain, implying that the risk of frailty, fall, and malnutrition was decreased. These findings indicated that community-based the intensive health care program is effective for relieving geriatric syndrome of the community dwelling elderly.

The Difference of Fitness according to Blood Pressure Level in Korean Women (한국성인 여성의 혈압수준에 따른 체력의 차이)

  • So, Wi-Young;Choi, Dai-Hyuk
    • 한국노년학
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    • v.29 no.1
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    • pp.135-147
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    • 2009
  • Recently, The number of hypertension is increasing with westernized diet and lack of exercise. Many researchers are trying to treat and prevent hypertension by exercise therapy. However, not only did most of studies analyze the effect and usefulness of exercise related to lowering hypertension, but also there is no analysis of the difference of fitness with regard to hypertension according to ages. It is assumed to be important research work to be continued to identify, from the public health's point of view, the difference of fitness with regard to hypertension according to ages can be a essential data for treating and preventing hypertension. Thus, this study is to identify the difference of fitness according to hypertension of adult female over 20s and emphasize the importance of fitness level to the hypertension. Also, this study is to devise valuable study by examining the difference of cardiovascular function. Subjects were 8889 of adult female over 20s. Subjects visited promotion of health center at Y Gu public health center and took comprehensive medical test including hypertension test in Seoul in Korea. It was divided into normal, prehypertension, stage I hypertension and stage II hypertension group by JNC7. The evaluation of cardiorespiratory function was by resting heart rate and lung capacity, the evaluation of fitness was by cardiorespiratory endurance, muscular endurance, muscular strength, power, agility, balance, and flexibility, and the difference of fitness was analyzed by ANCOVA revising independent variable of BMI, drinking, and smoking which affects hypertension. At result, there was significant difference between normal and hypertension group according to most ages in two variable of all cardiorespiratory function, seven fitness variable. Through this study, it was defined that hypertension group had lower cardiorespiratory function and fitness than normal group.

Effects of Intermittent Walking for Health Related Physical Fitness and Metabolic Syndrome Risk Factors in Elderly Women (간헐적인 걷기가 고령여성의 건강관련체력과 대사증후군 위험요인에 미치는 영향)

  • Kim, Sang-Hoon
    • 한국노년학
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    • v.29 no.4
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    • pp.1397-1411
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    • 2009
  • This study was aimed to examine the effects of intermittent walking on health related fitness and metabolic syndrome risk factors in elderly women. Forty five elderly women were randomly assigned to three groups: three 10-min walks per day, one 30-min walk per day or no exercise, respectively. Both walking groups exercised three days a week at moderate intensity for 12 weeks. Two-way repeated measures ANOVA was used to test the hypothesis with a significant level of α = .05. The results indicated that body composition(body weight, body mass index, percent body fat), muscle endurance, flexibility and cardiorespiratory fitness significantly increased after 12 weeks for both walking groups. However, it was found that muscle strength significantly increased only in a continuous walking group. Metabolic syndrome risk factors comprised of waist circumference, systolic blood pressure, triglyceride, high-density lipoprotein, and fasting glucose were significantly improved in both walking groups. In addition, there was a difference in these metabolic syndrome risk factors between pre and post exercise. The results of this study support the hypothesis that intermittent walking has a significant impact on health related physical fitness and metabolic syndrome rick factors in elderly women as continuous walking does.