• Title/Summary/Keyword: fatigue capacity

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Analysis Evaluation of Torsional Behavior of Hybrid Truss Bridge according to Connection Systems (격점구조형식에 따른 복합트러스교의 비틀림 거동 해석)

  • Choi, Ji-Hun;Jung, Kwang-Hoe;Kim, Tae-Kyun;Lee, Sang-Won;Kim, Jang-Ho Jay
    • Journal of the Korea Concrete Institute
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    • v.26 no.1
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    • pp.3-12
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    • 2014
  • Hybrid Truss Bridge (HTB) uses steel truss webs instead of concrete webs in prestressed box girder bridges, which is becoming popular due to its structural benefits such as relatively light self-weight and good aesthetics appearance. Since the core technology of this bridge is the connection system between concrete slabs and steel truss members, several connection systems were proposed and experimentally evaluated. Also, the selected joint system was applied to the real bride design and construction. The research was performed on the connection system, since it can affect the global behavior of this bridge such as flexural and fatigue behaviors as well as the local behavior around the connection region. The evaluation study showed that HTB applied to a curved bridge or an eccentrically loaded bridge had a weak torsional capacity compared to an ordinary PSC box girder bridge due to the open cross-sectional characteristic of HTB. Therefore, three types of girders with different joint system between truss web member and concrete slab were tested for their torsional capacity. In this study, the three different types of HTB girders under torsional loading were simulated using FEM analysis to investigate the torsional behavior of HTB girders more in detail. The results are discussed in detail in the paper.

Experimental Study on Flexural Capacity of Column Base Plate Made of Cast Steel (주강제 노출형 철골주각부의 휨 성능에 관한 실험 연구)

  • Lee, Sung Ho;Park, Hyung Chul;Oh, Bo Hwan
    • Journal of Korean Society of Steel Construction
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    • v.17 no.1 s.74
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    • pp.93-102
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    • 2005
  • Manufacturing conventional column base plate requires much manpower and time. In this research, a new method for constructing column base plate is introduced to improve on conventional methods through the use ofcast steel that is available for adjusting base plate thickness and enlarging base plate stiffness. The main purposes include reducing welding work, enlarging base plate stiffness, and clarifying the stress flow. Also, construction convenience and improvement in quality can be expected. For developing this cast steel base plate, test specimens of conventional and cast steel base plates are made and tested to analyze strength and stiffness. Also, the efficiency for long-term use is checked by fatigue tests. From these comparative tests, cast steel base plates have the same strength and stiffness as conventional base plates.

Hydrogen Compressor Cycle Analysis for the Operating Pressure of 50 MPa and High Charging Capacity (50 MPa급 대용량 수소압축기 사이클 해석)

  • Song, Byung-Hee;Myoung, No-Seuk;Jang, Seon-Jun;Kwon, Jeong-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.2
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    • pp.66-73
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    • 2020
  • In the hydrogen compression cycle, which is currently being developed, hydrogen is compressed to a very high pressure using a compressor, and then stored and used in a high-pressure vessel. This shows that an increase in the temperature of hydrogen in the vessel due to a pressure rise during the filling process and the pressure fatigue due to the repeated cycle may cause problems in the reliability of the vessel. In this paper, for the entire processes in a 50 MPa hydrogen compression system, theoretical and numerical methods were conducted to analyze the following: the temperature increase of hydrogen in the vessel and the time required to reach thermal equilibrium with the surroundings, the change in temperature of hydrogen passing through the pressure reducing valve, and the required capacity of the heat exchanger for cooling the vessel. The results will be useful for the design and construction of hydrogen compression systems, such as hydrogen charging stations.

A Study on the Mechanical Properties of Gas Pressure Welded Splices of Deformed Reinforcing Bar (가스압접 이형철근의 기계적 강도 특성 연구)

  • Jeon, Juntai
    • Journal of the Society of Disaster Information
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    • v.11 no.4
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    • pp.520-526
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    • 2015
  • Reinforcing bar splices are inevitable in reinforced concrete structure. In these days, there are three main types of splices used in reinforced concrete construction site - lapped splice, mechanical splice and welded splice. Low cost, practicality in construction site, less time consuming and high performance make gas pressure welding become a favorable splice method. However, reinforcing bar splice experiences thermal loading history during the welding procedure. This may lead to the presence of residual stress in the vicinity of the splice which affects the fatigue life of the reinforcing bar. Therefore, residual stress analysis and tensile test of the gas pressure welded splice are carried out in order to verify the load bearing capacity of the gas pressure welded splice. The reinforcing bar used in this work is SD400, which is manufactured in accordance with KS D 3504. The results show that the residual stresses in welded splice is relatively small, thus not affecting the performance of the reinforcing bar. Moreover, the strength of the gas pressure welded splice is high enough for the development of yielding in the bar. As such, the reinforcing bar with gas pressure welded splice has enough capacity to behave as continuous bar.

The Effectiveness of Ink Foot Print Analysis by Using Pre-post Oriental Medicine Music Therapy on Patient One Case with Cerebral Infarction (뇌경색 환자에게 실행한 한방음악치료 전후(前後)의 Ink foot print analysis 1례)

  • Lee, Seung-Hyun;Park, Kyoung-Su;Shin, Hyun-Dae
    • Journal of Korean Medicine Rehabilitation
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    • v.18 no.3
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    • pp.147-156
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    • 2008
  • Objectives : Oriental Medicine Music Therapy is a new way of treating and preventing various diseases and promoting health by means of music specially picked and designed to produce Qi(氣) fitting to an individual person in the areas of the structure of human body, physiological function, pathological change, diagnosis and treatment. Therefore, it can facilitate the efficiency of the treatment much better and faster than only with herb or acupuncture. Equilibrium between body and mind is its originality. Methods : A 38-year old man came to hospital suffering from left side weakness, dysarthria because of cerebral infarction. After one week's medication in the part of neurology, he was sent to the oriental medicine music therapy center, and he took ten times' medical treatments once a day. Before and after the treatments, implementing 'Ink foot print analysis', as for the movement capacity and walking of left side weakness, these results are acquired. Results and Conclusions : 1. Before the oriental medicine music therapy, except the acceleration and deceleration section, within three meters, a right foot's step was measured 30.55 cm and a left foot was measured 15.2 cm, and the step distance was 15.2 cm. After the 10 times treatments, the right foot's step was 112.6 cm, the left foot's step was 113 cm, and the step distance improved to 51.8 cm. 2. The normal person's average step is about 38 cm, and it could be decreased owing to a decreptitude, pain, fatigue, and the weakness of the legs. In spite of all, from the increased 50 cm step measurement with the patient's body condition, it means that his movement capacity is recovered. 3. In the measurement of walking time, before 10 times treatments, it took 46.35 seconds within 6M, but after the treatments, it increased to 7.47 seconds as same as a normal person's walking speed. 4. In insomnia, and the abnormality of a facial muscle, it shows lots of improvement, and even the accuracy of a pronunciation, but despite of the 10 times treatments, the 'ㄹ(r)' sound placed under a vowel is unclear. 5. Before the 10 times' treatments, he can move the left side shoulder with pain and cannot move below the left elbow. After the treatments, the pain was disappeared, and he was able to move over 60 cm without pain. And improving of the movement of fingers, he can beat over 8 times with a drumstick.

Effects of Custom Nutrition Education on Dietary Intakes and Clinical Parameters in Patients Diagnosed with Iron Deficiency Anemia (맞춤형 영양교육이 철결핍성 빈혈환자의 임상 지표 및 영양섭취 상태에 미치는 효과)

  • Kim, Hye-Jin;Mok, Hee-Jung;Hong, Jeong-Im;NamGung, Sin-A
    • Journal of the Korean Dietetic Association
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    • v.18 no.1
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    • pp.72-80
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    • 2012
  • This study examined the effects of custom nutrition education on dietary intakes and clinical parameters in patients diagnosed with iron deficiency anemia. A total of 34 patients visited the anemia clinic of Yeouido St. Mary's Hospital. Among these, only 16 patients were available for follow-ups. A follow-up was conducted by a clinical dietitian 2 months from the first nutrition education session. Patients were all women. For custom nutrition education, we investigated anthropometric data, dietary assessment (24 hr-recall, FFQ), and self-recognized anemic symptoms. Weight did not show a significant difference but hemoglobin, hematocrit (P<0.01), serum iron, and serum ferritin (P<0.05) were significantly increased after the nutrition education. Serum total iron binding capacity was significantly decreased (P<0.01). Self-recognized symptoms such as dizziness, fatigue (P<0.001), shortness of breath, headache (P<0.01), brittle nails, and sore tongue (P<0.05) were significantly improved. Daily intakes of protein (P<0.05), total iron (P<0.01), and animal iron (P<0.001) were significantly increased. A significantly negative correlation was observed between current serum iron and the intake of carbohydrates, fat, or phosphorus (P<0.05). But current serum ferritin showed a significantly positive correlation with the frequency of intake of meat, poultry, and fish. It could be concluded that the custom nutrition education might be effective on quality of diet as well as iron status and it might also improve the clinical parameters in patients diagnosed with the iron deficiency anemia.

Tubular Web Reduced Beam Section (TW-RBS) connection, a numerical and experimental study and result comparison

  • Zahrai, Seyed M.;Mirghaderi, Seyed R.;Saleh, Aboozar
    • Steel and Composite Structures
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    • v.23 no.5
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    • pp.571-583
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    • 2017
  • A kind of accordion-web RBS connection, "Tubular Web RBS (TW-RBS)" connection is proposed in this research. TW-RBS is made by replacing a part of web with a tube at the desirable location of the beam plastic hinge. This paper presents first a numerical study under cyclic load using ABAQUS finite element software. A test specimen is used for calibration and comparison of numerical results. Obtained results indicated that TW-RBS would reduce contribution of the beam web to the whole moment strength and creates a ductile fuse far from components of the beam-to-column connection. Besides, TW-RBS connection can increase story drift capacity up to 9% in the case of shallow beams which is much more than those stipulated by the current seismic codes. Furthermore, the tubular web like corrugated sheet can improve both the out-of-plane stiffness of the beam longitudinal axis and the flange stability condition due to the smaller width to thickness ratio of the beam flange in the plastic hinge region. Thus, the tubular web in the plastic hinge region improves lateral-torsional buckling stability of the beam as just local buckling of the beam flange at the center of the reduced section was observed during the tests. Also change of direction of strain in arc shape of the tubular web section is smaller than the accordion webs with sharp corners therefore the tubular web provides a better condition in terms of low-cycle fatigue than other accordion web with sharp corners.

Effects of Nutrition Counseling on Quality of Diet, Iron Status and Hematic Parameters in College Women Who Have Self-Recognized Anemic Symptoms (빈혈 자각증상이 있는 여대생에서 영양상담이 식사의 질, 철분 영양상태 및 혈액학적 지표에 미치는 영향)

  • Jeong, Sook-Hyun;Park, Jin-Hee;Lee, Hye-Ok;Cho, Ryo-Won
    • Korean Journal of Community Nutrition
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    • v.12 no.1
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    • pp.68-79
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    • 2007
  • Iron deficiency is the most common nutritional problem that affects people of all ages in both industrialized and developing countries. Especially, college women are the target population for dietary iron deficiency. Recent study showed that the nutritional status of college women was poor because of insufficient food consumption and repeatabled weight reduction. The purpose of this study was to investigate the effects of nutrition counseling on the diet quality, nutritional status of iron and hematic parameters in college women who have self-recognized anemic symptoms. Anthropometric and dietary assessments as well as blood analysis, were carried out before and after the 8 weeks of nutrition counseling. During the experimental period, the 31 subjects were given nutrition education by a clinical dietitian. Nutrition counseling consisted of pathology of anemia, nutrition information for iron deficient anemia, diet information of balanced meals and menu choices for eating out. As a result, the frequencies of consumption of legumen and vegetables significantly increased after nutrition counseling(p<0.05). Daily intakes of protein, especially animal protein, vitamin E, niacin, heme iron, and zinc significantly increased(p<0.05). After nutrition counseling, some self-reported clinical symptoms such as 'dizziness', 'fatigue', 'short of breath', 'headache', 'sleeplessness', and 'beating heart' were significantly improved. Serum levels of transferrin(p<0.01) and total iron binding capacity levels(p<0.05) significantly increased. It could be concluded that the 8 weeks of nutrition counseling might be effective on quality of diet as well as iron status and it might also improve the some hematic parameters in college women who have self-recognized anemic symptoms.

Improvement in Exercise Endurance by Hovenia dulcis Fruit Hot Water Extract in Mice (헛개나무열매 열수추출물 투여에 의한 흰쥐의 지구력 향상 효과)

  • Kwon, Tae-Hyung;Han, Joon-Hee;Lee, Sun-Yeop;Yu, Keun-Hyung
    • The Korean Journal of Food And Nutrition
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    • v.33 no.4
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    • pp.363-371
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    • 2020
  • This study was designed to evaluate the improvement in exercise endurance by Hovenia dulcis fruit hot water extract (HDWE) for the potential application as a functional food material. The effect was based on the evaluation of the forced-swimming capacity and changes in biochemical parameters in mice. Six-week-old mice were classified into four groups based on a randomized block design: the negative control group, the HDWE 50 mg/kg body weight group, the HDWE 200 mg/kg body weight group, and the 1-octacosanol 50 mg/kg body weight group (n=8 mice per group). The swimming exercise time in the HDWE-50 group was increased at 545±43 sec compared to the control group at 263±28 sec. The HDWE-200 fatigue indicators, lactate acid and ammonia content, decreased to 4.99±0.33 mg/mL and 0.63±0.05 mg/mL, respectively. In addition, the content of glycogen in the liver and muscle tended to increase in the group administered HDWE but was not significant. Likewise, the LDH and glucose contents were increased compared to the control group. The muscle damage indicators ALT (52.7±2.6 U/L) and AST (42.5±5.2 U/L) tended to decrease compared to the control group (76.4±10.2 U/L).

A Study on the Clinical Characteristics in Oral Lichen Planus (구강편평태선 환자의 임상적 특징에 관한 연구)

  • Yoon-Mi Lee;Myoung-Chan Kim;Jong-Youl Kim
    • Journal of Oral Medicine and Pain
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    • v.21 no.1
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    • pp.141-152
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    • 1996
  • Oral Lichen Planus(OLP) is a idiopathic chronic inflammatory disease with more difficult to clear and higher recurrent rate than cutaneous lesions. But, there has been no estabilished theories about the proper treatment for OLP. The purpose of this study is to examine the clinical feature, relationship with systemic disease and dental treatment of OLP patients of Korea and to gain helpful information about clinical characteristics and treatment of OLP. The subjects chosen for the study were 54 patients who had visited Department of Oral Diagnosis & Oral Medicine at Yonsei University Dental Hospital Dental Hospital and diagnosed as OLP. Previous clinical records has been reviewed and questionnaires, oral examination, laboratory examination were done and recorded. The following results were obtained : 1. Of the 54 patients, 21 were men and 33 were women with an average age of 47.8 years. 2. The most common intraoral site was bilateral buccal mucosa, followed by unilateral buccal mucosa, gingiva, vesibule, lip mucosa, glossal mucosa, palatal mucosa and mouth floor. 3. The mixed, erosive and reticular form of OLP was most frequent(83.3%) clinical form. 4. OLP patients with liver disease were 5, and drug medication patients were 7. But, we could not find its evidence of association with OLP. 5. Associated events on onset of symptom were stress, denture wearing, dental treatemtn, and common cold. 6. Associated symptoms were dry mouth, tingling, sore throat, and altered taste perception. 30.8% of patients had no specific associated symptoms. 7. Aggravating factors of symptom were peppery food, hot food, fatigue, toothpaste, salty food, sour food, tension, and conversation. Reducing factors were cold food, sleeping. 69.2% of patients had no specific reducing factors. 8. There were no significant differences between normal papulation and OLP patients in CBC, SGOT< SGPT, Serum iron, Total iron binding capacity. 66.7% of subjects were positive response to fungus study for Candida Albicans. The incidence of stress and dental treatment on onset of symptom appeared high in OLP patients. Especially, high incidence of positive response to fungus study for Candida albicans, prescription of anti-fungal agents and dental treatment considerations may be helpful to treatment of OLP.

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