• Title/Summary/Keyword: Initial Duration Method

Search Result 165, Processing Time 0.026 seconds

Fatigue performance evaluation of reinforced concrete element: Efficient numerical and SWOT analysis

  • Saiful Islam, A.B.M.
    • Computers and Concrete
    • /
    • v.30 no.4
    • /
    • pp.277-287
    • /
    • 2022
  • Due to the scarcity of extortionate experimental data, fatigue failure of the reinforced concrete (RC) element might be achieved economically adopting nonlinear finite element (FE) analysis as an alternative approach. However, conventional implicit dynamic analysis is expensive, quasi-static method overlooks interaction effects and inertia, direct cyclic analysis computes stabilized responses. Apart from this, explicit dynamic analysis may provide a numerical operating system for factual long-term responses. The study explores the fatigue behavior based on a simplified explicit dynamic solution employing nonlinear time domain analysis. Among fourteen RC beams, one beam is selected to validate under static loading, one under fatigue with the experimental study and other twelve to check the detail fatigue behavior. The SWOT (Strength, Weakness, Opportunities, Threats) analysis has been carried out to pinpoint the detail scenario in the adoption of numerical approach as an alternative to the experimental study. Excellent agreement of FE and experimental results is seen. The 3D nonlinear RC beam model at service fatigue limits is truthful to be used as an expedient contrivance to envisage the precise fatigue behavior. The simplified analysis approach for RC beam under fatigue offers savings in computation to predict responses providing acceptable accuracy rather than the complicated laboratory investigation. At higher frequency, the flexural failure occurs a bit earlier gradually compared to the repeated loading case of lower frequency. The deflection increases by 6%-10% at the end of first cycle for beams with increasing frequency of cyclic loading. However, at the end of fatigue loading, greater deflection occur earlier for higher load range because of more rapid stiffness degradation. For higher frequency, a slight boost in concrete compressive strains at an initial stage of loading has been seen indicating somewhat stepper increment. Stiffness degradation in larger loading cycle at same duration escalates the upsurge of the rate of strain in case of higher frequency.

A Study on the Analysis of Concrete Vertical form Demolding Timing Considering the Relationship between the Type of Coarse Aggregate and Ultrasonic Pulse Velocity (굵은 골재의 종류와 초음파 속도의 관계성을 고려한 콘크리트 수직 거푸집 해체 시점 분석에 관한 연구)

  • Nam, Young-Jin;Kim, Won-Chang;Choi, Hyeong-Gil;Lee, Tae-Gyu
    • Journal of the Korea Institute of Building Construction
    • /
    • v.23 no.6
    • /
    • pp.683-692
    • /
    • 2023
  • This research assesses the mechanical properties of concrete, utilizing both normal and lightweight aggregates, through measurements of compressive strength and ultrasonic pulse velocity. The study observed that concrete with normal aggregates exhibited higher compressive strength in its initial stages, whereas concrete with lightweight aggregates showed increased strength over time, likely attributed to the higher water absorption rate of lightweight aggregates. Ultrasonic pulse velocity generally registered higher in normal aggregate concrete, barring a specific duration, presumably due to variations in the internal pore structure of the aggregates. The correlation coefficient(R2) for the strength prediction equation, derived from the relationship between compressive strength and ultrasonic pulse velocity, exceeds 0.95. This high correlation suggests that the predictive equation based on these experimental findings is a reliable method for estimating concrete strength.

Study for Treatment Effects and Prognostic Factors of Bronchial Asthma -Follow Up Over 2 Years- (2년 이상 관찰중인 성안 기관지 천식환자의 치료 효과 및 예후인자에 관한 연구)

  • Choung, Bo-Young;Park, Jung-Won;Kim, Sung-Kyu;Hong, Chein-Soo
    • Tuberculosis and Respiratory Diseases
    • /
    • v.44 no.3
    • /
    • pp.559-573
    • /
    • 1997
  • Background : Asthma causes recurrent episodes of wheezing, breathlessness, chest tightness, and cough. These symptoms are usually associated with widespread but variable airflow limitation that is partly reversible either spontaneously or with treatment. The inflammation also causes an associated increase in airway responsiveness to a variety of stimuli. Method : Of the 403 adult bronchial asthma patients enrolled from March 1992 to March 1994 in Allergy Clinics of Severance Hospital in Yonsei University, this study reviewed the 97 cases to evaluate the treatment effects and to analyse prognostic factors. The patients were classified to five groups according to treatment responses ; group 1 (non control group) : patients who were not controlled during following up, group 2 (high step treatment group) : patients who were controlled longer than 3 months by step 3 or 4 treatment of "Global initiative for asthma, Global strategy for asthma management and prevention" (NHLBI/WHO) with PFR(%) larger than 80%, group 3 (short term control group) : patients who were controlled less than 1 year by step 1 or 2 treatment of NHLBI/WHO, group 4 (intermediate term control group) : patients who were controlled for more than 1 year but less than 2 years by step 1 or 2 treatment of NHLBI/WHO, group 5 (long term control group) : patients who were controlled for more than 2 years by step 1 or 2 treatment of NHLBI/WHO. Especially the patients who were controlled more than 1 year with negatively converted methacholine test and no eosinophil in sputum were classified to methacholine negative conversion group. We reviewed patients' history, atopy score, total IgE, specific IgE, methacholine PC20 and peripheral blood eosinophil count, pulmonary function test, steroid doses and aggrevation numbers after treatment. Results : On analysis of 98 patients, 20 cases(20.6%) were classified to group 1, 26 cases(26.8%) to group 2, 23 cases(23.7%) to group 3, 15 cases(15.5%) to group 4, and 13 cases(13.4%) to groups 5. There were no differences of sex, asthma type, family history, smoking history, allergic rhinitis and aspirin allergy among the groups. In long term control group, asthma onset age was younger, symptom duration was shorter, and initial pulmonary function was better. The long term control group required lower amounts of oral steroid. had less aggrevation during first 3months after starting treatment and shorter duration from enrollment to control Atopy, allergic skin test, sputum and blood eosinophil, total IgE, nonspecific bronchial responsiveness was not significantly different among the groups. Seven out of 28 patients who were controlled more than 1 years showed negatively converted methachloine test and no eosinophils in the sputum. The mean control duration was $20.3{\pm}9.7$ months and relapse did not occur. Conclusion : Patients who had asthma of onset age younger, shorter symptom duration, better PFT, lower treatment initial steps, lower amounts of steroid needs and less aggravation numbers after starting treatment were classified in the long term control groups compared to the others.

  • PDF

Combustion Characteristics of Volume Variation of Torch in a CVCC (토치 점화 장치의 체적에 따른 연소특성 파악)

  • Kwon, Soon-Tae;Kim, Hyeong-Sig;Choi, Chang-Hyeon;Park, Chan-Jun;Ohm, In-Young
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
    • /
    • 2010.04a
    • /
    • pp.166-170
    • /
    • 2010
  • Six different size of torch-ignition device were applied in a constant volume combustion chamber for evaluating the effects of torch-ignition on combustion. The torch-ignition device was designed six different volumes and same orifice size. The combustion pressures were measured to calculate the mass burn fraction and combustion enhancement rate. In addition, the flame propagations were visualized by shadowgraph method for the qualitative comparison. The result showed that the combustion pressure and mass burn fraction were increased when using the torch ignition device. And the combustion duration were decreased. The combustion enhancement rates of torch-ignition cases were improved in comparison with conventional spark ignition. Finally, the visualization results showed that the torch-ignition device the torch-ignition induced faster burn than conventional spark ignition due to the earlier transition to turbulent flame and larger flame surface, during the initial stage. And the initial flame propagation was effected torch-ignition volume.

  • PDF

Estimation of Permeability and Initial Pressure in Reservoir by DFIT Data Analysis (DFIT 자료 해석을 통한 저류층의 투과도 및 초기압력 추정)

  • Kim, Tae Hong;Lee, Sung Jun;Lee, Kun Sang
    • Tunnel and Underground Space
    • /
    • v.23 no.3
    • /
    • pp.169-179
    • /
    • 2013
  • Well testing in unconventional reservoirs, such as tight or shale gas formations, presents considerable challenges. It is difficult to estimate the reservoir properties in ultra-low permeability formation because of poor inflow prior to stimulation and excessive test duration. Moreover, radial flow may not develop in hydraulically fractured horizontal wells. For these reasons, the cost of test is high and the accuracy is relatively low. Accordingly, industry is turning to an alternate testing method, diagnostic fracture injection test (DFIT), which is conducted prior to the main hydraulic fracture treatments. Nowadays, DFIT are regarded as the most practical way to obtain good estimates of reservoir properties in unconventional reservoirs. Various methods may be used for interpreting DFIT data. This paper gives an explanation of those methods in detail and examines three actual field data. These show how various analysis methods can be applied to consistently interpret fracture closure pressure and time, as well as before and after closure flow regimes and reservoir properties from field data.

Improvement of Transfer Alignment Performance for Airborne EOTS (항공용 전자광학추적장비의 전달정렬 성능 개선)

  • Kim, Minsoo;Lee, Dogeun;Jeong, Chiun;Jeong, Jihee
    • Journal of Aerospace System Engineering
    • /
    • v.16 no.4
    • /
    • pp.60-67
    • /
    • 2022
  • An Electro-Optical Tracking System (EOTS) is an electric optical system with EO/IR cameras, laser sensors, and an IMU. The EOTS calculates coordinates of targets, using attitude and acceleration measured by the IMU. In particular for an armed aircraft, the performance of the weapon system depends on how quickly and accurately it acquires the target coordinates. The IMU should be operated after alignment is complete, to meet the coordinate accuracy required by the weapon system so the initial stabilization time of the IMU should be reduced, by quickly measuring the attitude and acceleration. Alignment is the process of determining the initial attitude by resolving the attitude error of the IMU, and the IMU of mission equipment such as an airborne EOTS, uses velocity matching based on the velocity from GPS/INS for aircraft navigation. In this paper, a method is presented to improve the transfer alignment performance of the airborne EOTS, by maneuvering aircraft and the mission equipment. First, the performance factor of the alignment was identified, as a heading error through the velocity matching model and simulation results. Then acceleration maneuvers and attitude changes were necessary, to correct the error. As a result of flight tests applied to an EOTS on a OOO aircraft system, the transfer alignment performance was improved as the duration time was decreased, by more than five times when the aircraft accelerated by more than 0.2g and the EOTS was moving until 6.7deg/s.

Continual Reassessment Method in Phase I Clinical Trials for Leukemia Patients (백혈병환자 대상의 제1상임상시험 연속재평가방법)

  • Lee, Joo-Hyoung;Song, Hae-Hiang
    • Communications for Statistical Applications and Methods
    • /
    • v.18 no.5
    • /
    • pp.581-594
    • /
    • 2011
  • The traditional method of 3+3 standard design and model-based Bayesian continual reassessment method (CRM) are commonly used in Phase I clinical trials to identify the maximal tolerated dose(MTD) of a new drug. In this paper we review clinical examples of Phase I trials that were carried out in patients with refractory or relapsed leukemia and myelodysplastic syndrome. The recently proposed 3+1+1 design and rolling-6 design can shorten the trial duration, when a very slow accrual of patients with a simple 3+3 standard design may result in the untimely termination of trials. Too conservative approaches in determining the dose levels in Phase I clinical trials can leave clinical investigators unable to accurately determine the MTD. When determining future patient doses, the designs that use a time-to-event CRM can cooperate late toxicities by accounting for the proportion of the observation period of each enrolled patient. With the CRM design, simulations under different scenarios during the trial are important in detecting the under- or over-estimation of the initial estimate of the dose-limiting toxicity rate for each dose level. We present the advantages and drawbacks of the designs used in Phase I clinical trials for leukemia patients.

Video-Assisted Thoracoscopic Surgery for Fibrinopurulent Empyema (섬유농성 농흉의 비디오 흉강경을 이용한 치료)

  • 손정환;모은경;지현근;김응중;신호승;신윤철
    • Journal of Chest Surgery
    • /
    • v.36 no.6
    • /
    • pp.404-410
    • /
    • 2003
  • Different treatment options are available according to the stage and duration of the empyema. Stage I empyema (exudate stage) is treated concurrently by the administration of appropriate antibiotics and chest tube drainage. Stage III empyema (organized stage) is considered for decortication through an open thoracotomy. However, the treatment of fibrinopurulent, stage II empyema remains controversial. Recently, debridement with the use of Video-Assisted Thoracoscopic Surgery (VATS) has been proposed for the treatment of stage II empyema. We analyzed and report our initial experience of 5 cases of stage II empyema, treated with the use of VATS. Material and Method: Between June 2001 and February 2002, 5 patients with fibrinopurulent empyema that did not respond to antibiotics, chest tube drainage or Percutaneous Catheter drainage (PCD), and instillation of fibrinolytic agent were treated by debridement and irrigation with the use of VATS. A CT scan was performed in all patients before the operation to confirm the diagnosis of loculated empyema and to detect additional lung parenchymal diseases. Result: All 5 patients underwent successful debridement and irrigation with the use of VATS and the chest tube was inserted properly. And no patients needed conversion to open thoracotomy. The ratio of sex was 4 : 1 (male : female), the mean age was 53 years old (range, 26~73 years), the mean operative time was 73.4 minutes (range, 52~95 minutes), the mean duration of postoperative chest tube placement was 12.4 days (range, 6~19 days), and the mean duration of postoperative hospital stay was 20.8 days (range, 10~36 days). In all patients, clinical symptoms such as pain and fever subsided and simple chest PA view revealed satisfactory lung expansion. No major postoperative complication was observed during the hospital course and no patient suffered from the recurrence of empyema in the follow-up period. Conclusion: We think that early operation with the use of VATS is safe and efficient for stage II empyema which did not respond to medical treatment(antibiotics and chest tube drainage), therefore, it can prevent stage II empyema from advancing to stage III, organized empyema.

Clinical review of Typhoid Fever Patients (장티브스에 관한 임상적 관찰)

  • 최정신
    • Journal of Korean Academy of Nursing
    • /
    • v.6 no.1
    • /
    • pp.60-71
    • /
    • 1976
  • The author reviewed the medical records of 96 typhoid fever patients who were diagnosed, admitted, and treated at Sea grave Memorial Hospital from January 1 , 1973 through August 31, 1975. Diagnosis was determined by clinical observation, aerology and bacteriology, eighty patients were treated medically, the remaining 16 patients required surgical intervention. The following results were obtained: 1) The age distribution of the patients revealed that 33.3% wert between 10 and 19 years old 21.9% were between 20 and 29, and 19.8% were between 30 and 39. The majority of patients were from these more active age groups. Male to female sex ratio was 1.3 : 1 2) Seasonal distribution was observed. Most illness occurred in the summer and autumn month 5. 3) 84. 3%of the patients came from farm families. 4) Duration between onset and admission averaged 16.0 days. The group without compilations was admitted after an average of 15. 1 days; The group with complications was ad-matted after an average of 19.4 days. 5) Methods of treatment before admission were as follows: 10.4% at medical clinics, 61, 5% at pharmacies (antibiotics 47.9%, other. drugs 13.5%), 7.3% by herb medications, 20.8% had no treatment. 6) Main clinical symptoms were as follows: fever 93.8%, headache 47.9%, abdominal pain 47.9%, chills 38.5%, cough 36.5%, general weakness 26.0%, nausea e vomiting 24.0% and generalized pain 21.9%. 7) Temperature of patients on admission: 22.9% were 39f or more, 67.6% were between 37℃ and 38℃, and 9.4% were 37℃ or less. 8) Occurrence of intensional bleeding after onset of disease averaged 9.3 days; perforation occurred at an average of 19. 1 days. 9) Interval between onset of major complication and surgical intervention averaged 2.8 days. 10) Among the 68 patients who underwent the bacteriological test the positive rate was 44.1% (30). The positive ,ales to, each separate culture method were as follows: 20.4% in the blood culture, 40.4% in the stool culture and 6.7% in the urine culture. Among these bacteriological positive patients 15 patients had a negative results or less than 160 titer of vidal reaction. 11) The initial vidal test of the total group showed a counts of 160 titer or more in 60.4% and less than 160 titer in 39.6%, 12) W. B. C. Counts in the uncomplicated group indicated that 32.5% were 6,000/㎣ or less, 47.5% were between 6,000 and 10,000, arid 20.0% were 10,000/㎣ or more. In the complicated group, 37.6% were 6,000/㎣ or less, 25,0% were 6,000-10,000/㎣ and 37.6% were 10,000/㎣ or more. 13) Duration of hospital stay of the patients averaged 6.4 days in the uncomplicated group and 12.7 days in the complicated group. 14) Subdiaphragmatic free air simple X-ray was found in 91.7% of the perforated cases. 15) Duration of antibiotic therapy until an febrile state was attained averaged 4.8 days in the uncomplicated group and 6.5 days in the complicated group. 16) Operative procedures were as follows: one layer simple closure of their perforation with or without debasement in 56.3%, drainage only in 6.3%, small bowel resection with primary anastomosis in 18.8% , externalization in 6.3%, cholecystectomy in 6.3%, The clinical findings of this study suggest the following recommendations. According to Top's report; 1% of typhoid fever patients treated with chlorarnphenicol and 2% of patients treated with other drugs become chronic carriers. Therefore, importance should be given to the strict control of these carriers. Immunization, improvement of sanitation and living standards are all needed for the prevention and treatment of disease, but a more serious problem is a lack of knowledge on the part of patients and their families. Thus it is most urgent to enlighten the citizens about the transmission and hygiene related to contagious disease. Legal restriction of sale of antibiotics at drug stores without a physician's prescription is an urgent matter for public health administrators. An even more important nursing responsibility is the reemphasis on health education both in the clinical setting and in the home.

  • PDF

Flowering and Seed Setting Characteristics of Eleutherococcus spp. Reproducted by Cutting Method (오갈피나무속 식물의 개화(開花)와 결보특성(結寶特性))

  • Cho, Seon-Haeng;Choi, Seong-Rak
    • Korean Journal of Medicinal Crop Science
    • /
    • v.9 no.3
    • /
    • pp.186-191
    • /
    • 2001
  • This study was conducted to find the flowering and seed setting characteristics of Eleutherococcus spp. Plants of Eleutherococcus spp. were 7 years old trees reproducted by cutting method using seven species in Gongju. Initial flowering date was foremost by May 9 in E. sieboldianus and hindmost by August 23 in E. divaricatus among seven species. Flowering duration was most short by 20 days in E. sieboldianus and extremely long by 42 days in E. sieboldianus. Number of flowers per plant in E. sieboldianus and E. chilsanensis were higher by 4677 and 4634 than those in E. divaricatus and E. sieboldianus by 780, 84, respectively. The fruit setting percent was the highest in E. sieboldianus by 95% and numbers of fruit setting per cluster showed the highest value by 153 in E. sieboldianus. The seed setting percent was almost same by ${92{\sim}95%}$ in E. sessiliflorus, E. chiisanensis, E. koreanus, E. divaricatus and E. seoulensis, but lower by ${11{\sim}37%}$ in E. senticosus and E. sieboldianus. The dry weight per plant and 100-fruit weight showed the highest value by 270g, 6.7g in E. sessiliflorus, respectively.

  • PDF