• 제목/요약/키워드: Long Term Equilibrium

검색결과 122건 처리시간 0.027초

프리스트레스트 콘크리트 휨 부재의 민감도 해석 (Sensitivity Analysis for Flexural Behaviors of PSC Members)

  • 이존자;이봉구;김민주;이용학
    • 한국구조물진단유지관리공학회 논문집
    • /
    • 제6권2호
    • /
    • pp.183-194
    • /
    • 2002
  • A general procedure to evaluate the sensitivity of design variables to stresses and strains in PSC flexural members is proposed. To accomplish the purpose of this study, long-term losses including creep, shrinkage, and PS steel relaxation are formulated based on the equilibrium states of the deformed sectional geometry. Thereby, the formulation follows the basic steps which consider the fundamental formulas adopted by CEB-FIP, ACI, and KCI rather than the age adjusted effective modulus concept. Twenty-one design variable including the material and geometrical properties of concrete, nonprestressing steel and prestressing steel, and the geometry of the cross section are considered in the sensitivity analysis. The gradients of the stresses and strains needed for the sensitivity assessment are calculated in a closed format. The derived formulation is applied to the T-type section PSC beam with prestressing and nonprestressing steels for the sensitivity analysis. The analytically calculated sensitivity results are compared with those numerically calculated to ensure the validity of the proposed procedure.

물리적 노화로 인한 미세 다공성 중합체의 투과성 저하 (Aging: Degradation of Permeability in Microporous Polymeric Membranes)

  • 김규남;고동연
    • 멤브레인
    • /
    • 제29권4호
    • /
    • pp.191-201
    • /
    • 2019
  • 산업 응용에 적용할 수 있는 중합체 막의 상용화 전에, 고성능 중합체가 실질적인 도전, 즉 연장된 서비스 시간에 대한 장기 안정성을 극복해야하는 과제가 남아있다. 매우 높은 분수 자유 부피(fractional free volume) 및 높은 투과성을 나타내는 고유한 미세 다공성 중합체(polymers of intrinsic microporosity)는 비효율적 무작위 패킹에 의해 생성된 여분의 부피가 물질의 부피적 평형에서 멀어짐과 동시에, 다시 부피적 평형 상태로 복귀하려는 특성, 즉 자유 부피를 줄여가는 특정으로 인해 투과성을 감소시키는 물리적 노화에 영향을 받기 쉽다. 본 논문에서 우리는 미세 다공성 고분자의 물리적 노화를 재검토하고 PIM에서 물리적 노화를 완화하려는 가장 두드러진 시도 중 일부를 논의할 것이다.

A Study on the Influence of China-Korea FTA on the Major Industries

  • SU, Shuai;ZHANG, Fan;YU, Li
    • 웰빙융합연구
    • /
    • 제3권4호
    • /
    • pp.1-4
    • /
    • 2020
  • Purpose: This research, based on the tariff reduction table negotiated by South Korea and China free trade area, the specific tariffs of the two countries in the implementation of the Korea-China Free Trade Agreement are calculated, and the global equilibrium model, the global trade analysis project (GTAP) model, is used to simulate and analyze the impact of the Korea-China free trade area on the output and trade of the two countries. Research design, data and methodology: The study conducted a survey on 2018 year GTAP 9.0data. After empirically analyzing the data, we believe that the Major industry in Korea and China will maintain its growth momentum. Results: This study shows that under the assumption that the average tariff of China and South Korea at the beginning of FTA was reduced to 20%, two scenarios were simulated. Two scenarios are simulated under the assumption that the average tariff of China and South Korea FTA will be reduced to 10%. Conclusions: This paper assumes that the average tariff of China-Korea FTA is set at 20%, 10% and zero tariff respectively in the early, middle and long term of the FTA construction. It considers the impact of China-Japan-Korea FTA on China- Korea FTA.

Evaluation of Americium Solubility in Synthesized Groundwater: Geochemical Modeling and Experimental Study at Over-Saturation Conditions

  • Hee-Kyung Kim;Hye-Ryun Cho
    • 방사성폐기물학회지
    • /
    • 제20권4호
    • /
    • pp.399-410
    • /
    • 2022
  • The solubility and species distribution of radionuclides in groundwater are essential data for the safety assessment of deep underground spent nuclear fuel (SNF) disposal systems. Americium is a major radionuclide responsible for the long-term radiotoxicity of SNF. In this study, the solubility of americium compounds was evaluated in synthetic groundwater (SynDB3), simulating groundwater from the DB3 site of the KAERI Underground Research Tunnel. Geochemical modeling was performed using the ThermoChimie_11a thermochemical database. Concentration of dissolved Am(III) in Syn-DB3 in the pH range of 6.4-10.5 was experimentally measured under over-saturation conditions by liquid scintillation counting over 70 d. The absorption spectra recorded for the same period suggest that Am(III) colloidal particles formed initially followed by rapid precipitation within 2 d. In the pH range of 7.5-10.5, the concentration of dissolved Am(III) converged to approximately 2×10-7 M over 70 d, which is comparable to that of the amorphous AmCO3OH(am) according to the modeling results. As the samples were aged for 70 d, a slow equilibrium process occurred between the solid and solution phases. There was no indication of transformation of the amorphous phase into the crystalline phase during the observation period.

인공 구조물에 의한 해빈변형 연구 (The Study of the Beach Change into Structures)

  • 김효섭;정병순;오병철
    • 한국수자원학회:학술대회논문집
    • /
    • 한국수자원학회 2004년도 학술발표회
    • /
    • pp.1445-1449
    • /
    • 2004
  • Even though there can be a relative long-term or short-term change of their size in natural beaches due to various changes of sea condition such as the location, weather condition (wind and rain) and sea water flow, the budget of deposits in a specific area is generally regarded to be in a condition of equilibrium in terms of technology. However, as coasts are developed by many different kinds of ways (such as construction of sea walls and estuarine, dredging for gathering the aggregate and shore protection construction for establishing a structure) and sources of silt and gravel from rivers are decreased in balanced beaches, the beaches are in a serious danger of lack of sand and sand sources which are one of the maul elements to consist of them. Many swimming beaches in East Sea are directly exposed by waves generated and transmitted from outer seas. On the other hand, the Song-Do sandy beach which is this study's target area has a great condition for beach development because it locates the deepest place that is relatively shallow in Young-Il Man and there is big energy decrease given to waves from outer seas while the waves are reaching the Song-Do beach. Nevertheless, it is considered that artificial condition changes such as dredging for site extension by POSCO, getting straight of Hyoung-San Gang river flow and extension of Po-Hang harbor caused the sand loss of the beach. Therefore, some recovery plans of Song-Do sandy beach will be presented in this study and they will be compared and examined each other by numerical modeling experiment. After that, the best plan will be recommended.

  • PDF

Glass Dissolution Rates From MCC-1 and Flow-Through Tests

  • Jeong, Seung-Young
    • 한국방사성폐기물학회:학술대회논문집
    • /
    • 한국방사성폐기물학회 2004년도 학술논문집
    • /
    • pp.257-258
    • /
    • 2004
  • The dose from radionuclides released from high-level radioactive waste (HLW) glasses as they corrode must be taken into account when assessing the performance of a disposal system. In the performance assessment (PA) calculations conducted for the proposed Yucca Mountain, Nevada, disposal system, the release of radionuclides is conservatively assumed to occur at the same rate the glass matrix dissolves. A simple model was developed to calculate the glass dissolution rate of HLW glasses in these PA calculations [1]. For the PA calculations that were conducted for Site Recommendation, it was necessary to identify ranges of parameter values that bounded the dissolution rates of the wide range of HLW glass compositions that will be disposed. The values and ranges of the model parameters for the pH and temperature dependencies were extracted from the results of SPFT, static leach tests, and Soxhlet tests available in the literature. Static leach tests were conducted with a range of glass compositions to measure values for the glass composition parameter. The glass dissolution rate depends on temperature, pH, and the compositions of the glass and solution, The dissolution rate is calculated using Eq. 1: $rate{\;}={\;}k_{o}10^{(ph){\eta})}{\cdot}e^{(-Ea/RT)}{\cdot}(1-Q/K){\;}+{\;}k_{long}$ where $k_{0},\;{\eta}$ and Eaare the parameters for glass composition, pH, $\eta$ and temperature dependence, respectively, and R is the gas constant. The term (1-Q/K) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_{0},\;{\eta}\;and\;E_{a}$ are the parameters for glass composition, pH, and temperature dependence, respectively, and R is the gas constant. The term (1-Q/C) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_0$, and Ea are determined under test conditions where the value of Q is maintained near zero, so that the value of the affinity term remains near 1. The dissolution rate under conditions in which the value of the affinity term is near 1 is referred to as the forward rate. This is the highest dissolution rate that can occur at a particular pH and temperature. The value of the parameter K is determined from experiments in which the value of the ion activity product approaches the value of K. This results in a decrease in the value of the affinity term and the dissolution rate. The highly dilute solutions required to measure the forward rate and extract values for $k_0$, $\eta$, and Ea can be maintained by conducting dynamic tests in which the test solution is removed from the reaction cell and replaced with fresh solution. In the single-pass flow-through (PFT) test method, this is done by continuously pumping the test solution through the reaction cell. Alternatively, static tests can be conducted with sufficient solution volume that the solution concentrations of dissolved glass components do not increase significantly during the test. Both the SPFT and static tests can ve conducted for a wide range of pH values and temperatures. Both static and SPFt tests have short-comings. the SPFT test requires analysis of several solutions (typically 6-10) at each of several flow rates to determine the glass dissolution rate at each pH and temperature. As will be shown, the rate measured in an SPFt test depends on the solution flow rate. The solutions in static tests will eventually become concentrated enough to affect the dissolution rate. In both the SPFt and static test methods. a compromise is required between the need to minimize the effects of dissolved components on the dissolution rate and the need to attain solution concentrations that are high enough to analyze. In the paper, we compare the results of static leach tests and SPFT tests conducted with simple 5-component glass to confirm the equivalence of SPFT tests and static tests conducted with pH buffer solutions. Tests were conducted over the range pH values that are most relevant for waste glass disssolution in a disposal system. The glass and temperature used in the tests were selected to allow direct comparison with SPFT tests conducted previously. The ability to measure parameter values with more than one test method and an understanding of how the rate measured in each test is affected by various test parameters provides added confidence to the measured values. The dissolution rate of a simple 5-component glass was measured at pH values of 6.2, 8.3, and 9.6 and $70^{\circ}C$ using static tests and single-pass flow-through (SPFT) tests. Similar rates were measured with the two methods. However, the measured rates are about 10X higher than the rates measured previously for a glass having the same composition using an SPFT test method. Differences are attributed to effects of the solution flow rate on the glass dissolution reate and how the specific surface area of crushed glass is estimated. This comparison indicates the need to standardize the SPFT test procedure.

  • PDF

구조변화를 고려한 한국의 LNG 가격 추정 (Estimation of Korean LNG Price Allowing a Structural Change)

  • 조홍종;한원희
    • 자원ㆍ환경경제연구
    • /
    • 제24권4호
    • /
    • pp.679-708
    • /
    • 2015
  • 현재 한국은 천연가스 수요의 99%를 LNG 형태로 해외로부터 수입하고 있으며, 80% 이상을 유가에 연동된 가격 공식을 갖고 있는 장기 LNG 계약을 통해 도입하고 있다. LNG 도입 가격 추정은 다양한 천연가스 이해 관계자들에게 중요한 정보를 제공하게 됨에도 불구하고 아직까지 활용할 수 있는 계량 모형이나 실증 분석이 이루어지지 않았다. 따라서 본 논문에서는 한국 LNG 도입 가격의 특성을 반영하여 국제 유가와 장기적인 균형 관계(공적분 관계)가 있는지와 그러한 장기 균형 관계에 구조적 변화가 있었는지를 실증적으로 분석하고, 한국의 LNG 가격 추정 모형으로 구조변화를 고려한 조건부 확장 오차수정모형을 구축하였다. 최종적으로 선정된 조건부 확장 오차수정모형에 따르면, 국제 유가의 충격은 과거와는 다른 양상으로 한국의 LNG 가격에 비선형적으로 파급된다.

Developmental Disability Animal Model Based on Neonatal Lipopolysaccharide with Altered 5-HT Function

  • Kim, Jae-Goo;Kim, Min-Soo;Lee, Se-Oul;Kim, Gun-Tae;Lee, Jong-Doo;Kim, Dong-Goo
    • The Korean Journal of Physiology and Pharmacology
    • /
    • 제11권3호
    • /
    • pp.113-119
    • /
    • 2007
  • Developmental disability shows life-long behavioral abnormality with no significant physical malformation. This study was undertaken to develop an animal model for developmental disability by using two-factor approach. Lipopolysaccharide (LPS), a bacterial toxin, and NAN-190, a $5-HT_{1A}$ receptor antagonist, were administered to Sprague-Dawley rats on postnatal day (PND) 5 to induce inflammation and an altered 5-HT system, respectively. Long-term alteration of behavior occurred in the drug-treated groups. The LPS-treated group showed impaired motor coordination in the Rota-rod test. The LPS- treated or both LPS and NAN-190-treated groups showed impaired fore-paw muscle power in the wire maneuver test. These groups also showed decreased white matter volume and increased serotonergic fibers. The LPS and NAN-190-treated group also exhibited neurologic deficit in the placing reaction test and impaired equilibrium function in the tilt table test. The results showed that a variety of altered behaviors can be generated by two factor model, and suggested that combination of important etiologic factors and possible underlying defects is a promising strategy of establishing an animal model for developmental disabilities.

환율과 경기가 우리나라의 대 동남아시아 항만 수출입에 미치는 영향 (Effects of the Exchange Rate and Industrial Activity on Export to and Import from the Southeast Asia Via Korean Port)

  • 김창범
    • 한국항만경제학회지
    • /
    • 제27권4호
    • /
    • pp.207-218
    • /
    • 2011
  • 본고에서는 환율과 경기가 우리나라의 대 동남아시아 항만 수출입에 미치는 영향을 분석하였다. 분석을 시작하기 이전에 먼저 단위근 검정과 공적분 검정을 이용하여 변수와 모형이 안정적인가를 살펴보았다. 단위근 검정 결과 1차 차분한 시계열자료는 귀무가설의 기각에 성공함에 따라 Johansen 검정을 실시하여 적어도 하나의 공적분 벡터가 존재하는 것으로 나타났다. 이에 따라 공적분 벡터와 VECM을 추정하였다. 추정결과 대체적으로 가격변수와 소득변수의 부호는 이론과 일치하였다. 수출의 경우 수출의 환율탄력성의 경우 그 크기의 순서는 인도네시아가, 수출의 소득탄력성의 경우는 베트남이 가장 큰 것으로 나타났다. 그리고 오차수정항 크기의 순서는 베트남이 가장 큰 것으로 나타났다. 또한 수입의 경우 수입과 소득의 환율탄력성의 경우 그 크기의 순서는 베트남이 가장 큰 것으로 나타났다. 그리고 오차수정항 크기의 순서는 말레이시아가 가장 큰 것으로 나타났다. 결론적으로 대부분의 국가들에서 수출의 환율과 경기탄력성보다 수입의 환율과 경기탄력성이 크게 나타남으로써 수출시장 확대에는 큰 한계가 존재함을 보여주었다.

물리적 처리에 따른 낙엽송 방부원주목의 표면할렬 방지효과 (Surface Checking Reduction Effect of Preservative-treated Korean Larch Round-woods with Various Physical Treatments)

  • 방성준;오정권;이상준;박준호;장성일;이전제
    • Journal of the Korean Wood Science and Technology
    • /
    • 제45권1호
    • /
    • pp.107-115
    • /
    • 2017
  • 본 연구에서는 국산 낙엽송 방부원주목을 대상으로 물리적 처리(인사이징, 배할, 열기건조)에 따른 표면할렬 방지효과와 장기 사용연한 확보 가능성을 실험적으로 검토하였다. 표면할렬이 목재 내 외부의 급격한 수분경사로 인해 발생하기 때문에 본 연구에서는 국내 최저 평형함수율 조건[온도($2^{\circ}C$), 습도(44.6%)]에서 시험편이 평형함수율(8.6%)에 도달할 때까지 실험을 진행하였다. 물리적 처리에 따른 표면할렬 방지효과를 검토한 결과, 무처리 시험편(Type C)의 경우, 모든 시험편에서 약제 침투 깊이보다 깊은 할렬이 발생하여 장기 내부후성을 확보할 수 없는 것으로 나타났다. 한편, 약제침투도 개선을 위해 사용하는 인사이징 처리만으로도 시험편의 80%에서 약제침투깊이보다 깊은 표면할렬을 방지하는 효과가 있었다. 그러나 국내에서 할렬을 방지하고자 사용하는 배할 처리는 인사이징 처리에 비하여 약제 침투깊이보다 깊은 표면할렬을 야기하였다.