• Title/Summary/Keyword: Limit state function

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A Failure Probability Estimation Method of Nonlinear Bridge Structures using the Non-Gaussian Closure Method (Non-Gaussian Closure 기법을 적용한 비선형 교량 구조계의 파괴확률 추정 기법)

  • Hahm, Dae-Gi;Koh, Hyun-Moo;Park, Kwan-Soon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.1
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    • pp.25-34
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    • 2010
  • A method is presented for evaluating the seismic failure probability of bridge structures which show a nonlinear hysteretic dynamic behavior. Bridge structures are modeled as a bilinear dynamic system with a single degree of freedom. We regarded that the failure of bridges will occur when the displacement response of a deck level firstly crosses the predefined limit state during a duration of strong motion. For the estimation of the first-crossing probability of a nonlinear structural system excited by earthquake motion, we computed the average frequency of crossings of the limit state. We presented the non-Gaussian closure method for the approximation of the joint probability density function of response and its derivative, which is required for the estimation of the average frequency of crossings. The failure probabilities are estimated according to the various artificial earthquake acceleration sets representing specific seismic characteristics. For the verification of the accuracy and efficiency of presented method, we compared the estimated failure probabilities with the results evaluated from previous methods and the exact values estimated with the crude Monte-Carlo simulation method.

The Rearch Of Method in the Appropriate number of Demand and Supply of OMD (한의사인력(韓醫師人力) 공급(供給)의 적정화방안(適定化方案) 연구(硏究))

  • Lee, Jong-Soo
    • The Journal of Korean Medicine
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    • v.19 no.1
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    • pp.299-326
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    • 1998
  • 1. Comparison of demand and supply A. Assumption of estimation of demand and supply we will briefly assumptions used for presumption once more before comparing the result of estimation of demand and supply examined previously 1) supply - The average applying rate for state. examination of graduate: ${\alpha}$=1.03109 - The ratio of successful applicants of state examinations: ${\beta}$=0.97091 - Mortality classified by age : presumed data of the Bureau of statistics - Emigrating rate: 0 % - Time of retire: unconsidered - An army doctor number: unconsidered and regard number of employed oriental medicine doctor. - Standard of 1995 : The number of survival oriental medicine doctor is 8195. the number of employed oriental medicine doctor is 7419. 2) demand - derivated demand method Daily the average amount of medical treatment: according to medical insurance federation data. there is 16 or 6 non allowance patient, we consider amount of medical treatment as 22 persons in practical because 21.94 persons (founded practical examination) are converted to allowance in comming demand. Daily the proper amount of medical treatment: 7 hours form -35 persons 5 hours 30 minutes form -28 persons. Yearly medical treatment days: 229 days. 255 days. 269 days . Increasing rate of visiting hospital days: -1996 year. 1997 year. 1998 year- . Rate of applying insurance: yearly average 71.51% (among the investigated patient) B. Comparison of total sum result 1) supply (provision) Table Ⅳ-1 below shows the estimation of the oriental medicine doctor in the future.

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  • Effect of K-ADL·K-IADL and Quality of life in Day Hospital Program for Stroke Patients (뇌졸중 환자의 낮병원 프로그램이 도구적·일상생활활동 수행 능력과 삶의 만족도에 미치는 영향)

    • Park, Chang-Sik;Song, Byung-Ho
      • The Journal of the Korea Contents Association
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      • v.12 no.11
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      • pp.267-277
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      • 2012
    • This study was to evaluate the effects how to have an influence on activities daily living and quality of life in day hospital program for the stroke patient. 41 experimental groups and 41 control groups in National rehabilitation hospital selected and examined K-ADL, K-IADL and quality of life. The result of this study indicated that experimental group was higher than control group in activity daily living performance and instrumental activity daily living performance. also experimental group was higher than control group all of total items in quality of life. age and economic state of general characteristic had an effect on K-ADL, K-IADL and quality of life and economic state, scholarship, marriage, job, helper had effect on quality of life. pain, social function, mental health, physical role in item of quality of life had effect on K-ADL and limit of physical role had best effect on K-IADL. Consequently we found that it needs to continuous rehabilitation to maintain body function, to prevent secondary disability, to improve social integration and quality of life for stroke patient actually.

    The Relationship Between Intestinal Iron Absorption and Hepatic Parenchymal Cell Damage (간실질세포(肝實質細胞)의 손상(損傷)이 철흡수(鐵吸收)에 미치는 영향(影響)에 관(關)한 실험적(實驗的) 연구(硏究))

    • Kim, Mok-Hyun;Hahn, Shim-Suck
      • The Korean Journal of Nuclear Medicine
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      • v.5 no.2
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      • pp.19-40
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      • 1971
    • Since the iron balance is maintained by regulated intestinal absorption rather than regulated excretion, there have been many reports concerning the factors which may influence the intestinal iron absorption. As the liver is the largest iron storage organ of the body, any hepatocellular damage may result in disturbances in iron metabolism, e,g., frequent co-existence of hemochromatosis and liver cirrhosis, or elevated serum iron level and increased iron absorption rate in patients with infectious hepatitis or cirrhosis. In one effort to demonstrate the influence of hepatocellular damage on intestinal iron absortion, the iron absorption rate was measured in the rabbits whose livers were injured by a single subcutaneous injection of carbon tetrachloride (doses ranging from 0.15 to 0.5cc per kg of body weight) or by a single irradiation of 2,000 to 16,000 rads with $^{60}Co$ on the liver locally. A single oral dose of $1{\mu}Ci\;of\;^{59}Fe$-citrate with 0.5mg of ferrous citrate was fed in the fasting state, 24 hours after hepatic damage had been induced, without any reducing or chelating agents, and stool was collected for one week thereafter. Serum iron levels, together with conventional liver function tests, were measured at 24, 48, 72, 120 and 168 hours after liver damage had been induced. All animals were sacrificed upon the completing of the one week's test period and tissue specimens were prepared for H-E and Gomori's iron stain. Following are the results. 1. Normal iron absorption rate of the rabbit was $41.72{\pm}3.61%$ when 0.5mg of iron was given in the fasting state, as measured by subtracting the amount recovered in stool collected for 7 days from the amount given. The test period of 7 days is adequate, for only 1% of the iron given was excreted thereafter. 2. The intestinal iron absorption rate and serum iron level were significantly increased when the animal was poisoned by a single subcutaneous injection of 0.15cc. per kg. of body weight of carbon tetrachloride or more, or the liver was irradiated with a single dose of 12,000 rads or more. The results of liver function tests which were done simultaneously remained within normal limit except SGOT and SGPT which were somewhat increased. 3. In each case, there has been good correlation between the extent of liver cell damage and degree of increased iron absorption rate or serum iron level. 4. The method of liver damage appeared to make no obvious difference in the pattern of iron deposit in liver. This may be partly due to the fact that tissue specimens were obtained too late, for by this time the elevated serum iron level had returned within normal range and the pathological changes were almost healed. 5. The possible factors and relationship between intestinal iron absorption and hepatic parenchymal cell damage has been discussed.

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    Critical Strengthening Ratio of CFRP Plate Using Probability and Reliability Analysis for Concrete Railroad Bridge Strengthened by NSM (확률.신뢰도 기법을 적용한 CFRP 플레이트 표면매립보강 콘크리트 철도교의 임계보강비 산정)

    • Oh, Hong-Seob;Sun, Jong-Wan;Oh, Kwang-Chin;Sim, Jong-Sung;Ju, Min-Kwan
      • Journal of the Korea Concrete Institute
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      • v.21 no.6
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      • pp.681-688
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      • 2009
    • The railroad bridges have been usually experienced by vibration and impact in service state. With this reason, it is important that the effective strengthening capacity should be considered to resist the kind of service loading. In this study, NSM strengthening technique is recommended for the concrete railroad bridge because of its better effective resistance for dynamic loading condition and strengthening cost than the conventional externally bonded strengthening using fiber sheet. However, to widely apply NSM method for the concrete railroad bridge, it needs that the strengthening ratio has to be reasonably evaluated with geometrical and material uncertainties, especially for the concrete bridge under long-term service state without the apparent design history and detail information such as concrete compressive strength, reinforcing ratio, railroad characteristics. The purpose of this study is to propose the critical strengthening ratio of CFRP plate for the targeted concrete railroad bridge with uncertainties of deterioration of the structures. To do this, Monte Carlo Simulation (MCS) for geometrical and material uncertainties have been applied so that this approach may bring the reasonable strengthening ratio of CFRP plate considering probabilistic uncertainties for the targeted concrete railroad bridge. Finally, the critical strengthening ratio of NSM strengthened by CFRP plate is calculated by using the limit state function based on the target reliability index of 3.5.

    A Study on efficiency of security police through cooperation with private sector (민간영역과의 공조에 의한 경비경찰 효율화에 관한 연구)

    • Kim, Jin-Hyeok
      • Korean Security Journal
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      • no.20
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      • pp.119-140
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      • 2009
    • It seems that security police's business to secure safety of state and citizens has existed since the mankind began to create a community. State was not fully responsible for such security business from the beginning. The business was carried out autonomously by the private sector for a long period. However, as the state system had been strengthened, the public sector absorbed the function. But in the modern society where various risks exist, safety of society could not be guaranteed only by public police. Accordingly, cooperation with the private sector is indispensable. In the limit of public police, autonomous organization of security companies and general citizens is expanding its scope. As a result, they should exercise partnership as a tripod to build social safety net. Security police failed to secure manpower exclusively responsible for security, despite various businesses and excessive mobilization. Accordingly, their professionalism and ability to cope with crisis are being questioned. In particular, efficiency of security police is becoming a more urgent issue in an era of international terrorism. Private sector can be classified into security companies and private autonomous organization. In case of security companies, the problem is quality and business ability of guards compared to a rapid external growth such as quantitative expansion and advancement into various businesses. In terms of pure private activity, the necessity of understanding of public police activity and conditions for organizational and continuous activity should be prepared. To tide over such problems and effectively achieve the common goal, changes in the method of employment, new establishment of security police department, and strengthening of professionalism and crisis management ability are necessary in the public police sector. In case of security companies, improvement of relations with public police through joint education, strengthening of business ability and activation of business cooperation through these matters are necessary. To maximize activity of pure private sector, it needs to establish reserve police, manage such private autonomous organization and bolster publicity with citizens.

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    Thyroid Function Test in Thyroid Diseases and Pregnancy - The diagnostic value of free thyroxine by RIA - (임신 및 각종 갑상선질환에서 갑상선 기능 판정에 관한 연구 - 혈청유리 $T_4$의 진단적 의의에 관한 고찰 -)

    • Yoo, M.H.;Yoon, H.J.;Shin, Y.T.;Lee, J.C.;Chung, S.I.;Cho, B.Y.;Lee, M.;Lee, M.C.
      • The Korean Journal of Nuclear Medicine
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      • v.15 no.1
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      • pp.1-11
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      • 1981
    • To evaluate the diagnostic accuracy of the measurement of free thyroxine (FT4) by radioimmunoassay, we measured free $T_4\;and\;T_4,\;T_3,\;T_3RU$, TSH and TBG serum levels by radioimmunoassay in 18 healthy persons and 52 patients with various thyroid diseases and 11 normal pregnant women. The results are as follows. 1. In 19 cases of overt hyperthyroidism, $T_3,\;free\;T_4$ and FTI, $T_4/TBG$ ratio reflect hyperfunction in all cases. $T_4$ is increased in 94% (18/19) and TBG and TSH are decreased in 79% (15/19). 2. In 8 patients with overt hypothyroidism, TSH is increased in all cases and free $T_4$ and FTI is decreased in all cases. $T_4$ is decreased in 87.5% (7/8), $T_3$ is decreased in 75% (6/8) and $T_4/TBG$ ratio is decreased in 62.5% (5/8). 3. In 5 patients who are clinically in euthyroid state after treatment of hyperthyroidism, $T_4,\;free\;T_4$, FTI and TSH are in the normal range in all cases and $T_3$ is normal in 60% (3/5) and slightly increased in 40% (2/5). 4. In 10 patients who showed clinically borderline hypothyroidism after treatment of hyperthyroidism, TSH is increased in all cases and free $T_4$ and FTI are decreased in all cases, but $T_4\;and\;T_3,\;T_4/TBG$ ratio are in the normal limit in all cases. So after treatment of hyperthyroidism, TSH, free $T_4$ or FTI are recommended as optimal thyroid function test. 5. In normal pregnancy, free $T_4$, FTI and $T_4/TBG$ ratio reflect normal function, but the other parameters revealed unreliable due to the influence of increased TBG. Also TBG and TSH level in pregnancy is increased significantly compared with normal healthy control group. 6. The coefficients of correlation between free $T_4$ and FTI were 0.862 (p<0.001) and 0.685 (p<0.001) between free $T_4\;and\;T_4/TBG$ ratio. In most patients, diagnostic value of free $T_4$ was comparable and even superior to FTI, so free $T_4$ measurement can be used routinely with thyrotropin assay in the diagnosis of hypothyrodism or with $T_3$ for the diagnosis of hyperthyroidism.

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    Effect of Partially Restrained Connections on Seismic Risk Evaluation of Steel Frames (강 뼈대 구조물의 지진위험도 평가에 대한 부분구속 접합부의 영향)

    • 허정원;조효남
      • Journal of the Computational Structural Engineering Institute of Korea
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      • v.14 no.4
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      • pp.537-549
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      • 2001
    • The effect of partially restrained(PR) connections and the uncertainties in them on the reliability of steel frames subjected to seismic loading is addressed. A stochastic finite element method(SFEM) is proposed combining the concepts of the response surface method(RSM), the finite element method(FEM), the first-order reliability method (FORM), and the iterative linear interpolation scheme. The behavior of PR connections is captured using moment-relative rotation curves, and is represented by the four-parameter Richard model. For seismic excitation, the loading, unloading, and reloading behavior at PR connections is modeled using moment-relative rotation curves and the Masing rule. The seismic loading is applied in the time domain for realistic representation. The reliability of steel frames in the presence of PR connections is calculated considering all major sources of nonlinearity. The algorithm is clarified with the help of an example.

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    Static performance of a new GFRP-metal string truss bridge subjected to unsymmetrical loads

    • Zhang, Dongdong;Yuan, Jiaxin;Zhao, Qilin;Li, Feng;Gao, Yifeng;Zhu, Ruijie;Zhao, Zhiqin
      • Steel and Composite Structures
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      • v.35 no.5
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      • pp.641-657
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      • 2020
    • A unique lightweight string truss deployable bridge assembled by thin-walled fiber reinforced polymer (FRP) and metal profiles was designed for emergency applications. As a new structure, investigations into the static structural performance under the serviceability limit state are desired for examining the structural integrity of the developed bridge when subjected to unsymmetrical loadings characterized by combined torsion and bending. In this study, a full-scale experimental inspection was conducted on a fabricated bridge, and the combined flexural-torsional behavior was examined in terms of displacement and strains. The experimental structure showed favorable strength and rigidity performances to function as deployable bridge under unsymmetrical loading conditions and should be designed in accordance with the stiffness criterion, the same as that under symmetrical loads. In addition, a finite element model (FEM) with a simple modeling process, which considered the multi segments of the FRP members and realistic nodal stiffness of the complex unique hybrid nodal joints, was constructed and compared against experiments, demonstrating good agreement. A FEM-based numerical analysis was thereafter performed to explore the effect of the change in elastic modulus of different FRP elements on the static deformation of the bridge. The results confirmed that the change in elastic modulus of different types of FRP element members caused remarkable differences on the bending and torsional stiffness of the hybrid bridge. The global stiffness of such a unique bridge can be significantly enhanced by redesigning the critical lower string pull bars using designable FRP profiles with high elastic modulus.

    Non-linear Shimmy Analysis of a Nose Landing Gear with Friction (마찰을 고려한 노즈 랜딩기어의 비선형 쉬미 해석)

    • Yi, Mi-Seon;Bae, Jae-Sung;Hwang, Jae-Hyuk
      • Journal of the Korean Society for Aeronautical & Space Sciences
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      • v.39 no.7
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      • pp.605-611
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      • 2011
    • Shimmy is a self-excited vibration in lateral and torsional directions of a landing gear during either the take-off or landing. It is caused by a couple of conditions such as a low torsional stiffness of the strut, a free-play in the landing gear, a wheel imbalance, or worn parts, and it may make the aircraft unstable. This study was performed for an analysis of the shimmy stability on a small aircraft. A nose landing gear was modeled as a linear system and characterized by state-equations which were used to analyze the stability both in the frequency and time-domain for predicting whether the shimmy occurs and investigating a good design range of the important parameters. The root-locus method and the 4th Runge-Kutta method were used for each analysis. Because the present system has a simple mechanism using a friction to reinforce the stability, the friction, a non-linear factor, was linearized by a describing function and considered in the analysis and observed the result of the instability reduction.


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