• Title/Summary/Keyword: parameter sensitivity

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A study on the Dynamic Behavior Enhancement of the Korean High-speed Train (고속열차의 주행동특성 개선에 관한 연구)

  • Jeon, Chang-Sung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.81-87
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    • 2017
  • This paper describes the dynamic behavior and enhancement of Korean high-speed trains. The tail vibration reduction method of the yaw damper installation method change, which was derived from previous research, was applied to the running test of high-speed train. In addition, the vibration reduction method for the entire vehicle was derived by a numerical method and its effect was confirmed by a running test. The improved design was applied to the double-deck high-speed train coaches and the commissioning proceeded without problems in dynamic behavior. Sensitivity analysis of the suspension parameters affecting the critical speed of Korean next-generation high-speed trains was performed and four design variables that greatly affected the critical speed were derived. These were in the order of the primary elastic joint x-directional stiffness, the secondary yaw damper series stiffness, the secondary lateral damper damping coefficient, and the carbody damper damping coefficient. By optimizing the design variables, the suspension parameter that improves the critical speed by 23.3% can be used in the commercial designs of Korean next-generation high-speed trains.

Study on the Calculation Method of Design Flood Discharge of Dam (댐 설계홍수량 산정방법에 관한 연구)

  • Lee, Jai-Hong;Moon, Young-Il;Beck, Yoo-Hyun;Jang, Kwang-Jin
    • Proceedings of the Korea Water Resources Association Conference
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    • 2011.05a
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    • pp.277-281
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    • 2011
  • In this study, past method and recent method for flood discharge with domestic multi-purpose dams in Korea were compared and analyzed with respect to the scale of watershed. Rainfall depth, temporal distribution, effective rainfall, rainfall-runoff model, parameter estimation and base flow were selected as the principal factors affecting flood discharge and effects on flood discharge were analyzed quantitatively by using sensitivity analysis. The results showed that the flood discharges calculated by past and recent method increased and decreased with a wide range of discharge with respect to the scale of watershed. The reason for decrease of flood discharge is the exchange of temporal distribution pattern of rainfall and the principal reason for increase of flood discharge are the increase of rainfall depth by unusual weather phenomena and the difference of estimation method of parameters of unit hydrograph.

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Low Temperature Deposition of Microcrystalline Silicon Thin Films for Solar Cells (태양전지용 미세결정 실리콘 박막의 저온 증착)

  • Lee, J.C.;Yoo, J.S.;Kang, K.H.;Kim, S.K.;Yoon, K.H.;Song, J.;Park, I.J.
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1555-1558
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    • 2002
  • This paper presents deposition and characterizations of microcrystalline silicon(${\mu}c$-Si:H) films prepared by hot wire chemical vapor deposition at substrate temperature below $300^{\circ}C$. The $SiH_4$ Concentration$[F(SiH_4)/F(SiH_4)+F(H_2)]$ is critical parameter for the formation of Si films with microcrystalline phase. At 6% of silane concentration, deposited intrinsic ${\mu}c$-Si:H films shows sufficiently low dark conductivity and high photo sensitivity for solar cell applications. P-type ${\mu}c$-S:H films deposited by Hot-Wire CVD also shows good electrical properties by varying the rate of $B_2H_6$ to $SiH_4$ gas. The solar cells with structure of Al/nip ${\mu}c$-Si:H/TCO/glass was fabricated with sing1e chamber Hot-Wire CVD. About 3% solar efficiency was obtained and applicability of HWCVD for thin film solar cells was proven in this research.

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Studies on the Preparation of Digestive Enzyme Tablets(III) (소화효소정제(消化酵素錠劑)의 제조(製造)에 관(關)한 연구(硏究) (제3보)(第3報))

  • Kim, Yong-Bae;Yi, Pyong-Kuk;Min, Shin-Hong;Shin, Hyun-Jong
    • Journal of Pharmaceutical Investigation
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    • v.6 no.2
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    • pp.69-82
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    • 1976
  • Tablet product design problem was structured as constrained optimization problem and subsequently solved by multiple regression analysis and Lagrangian method of optimization. We used Lagrangian method for the purpose of finding the reason of the previous results. Biodiastase and cellulase were the enzymes, chosen, $Avicel{\circledR}$ and corn starch or calcium carboxy methyl cellulose were the binder and disintegrant, respectively. The effect of the dry binder and disintegrant concentration on tablet hardness, friability, volume, disintegration time was recorded. Optimization of this parameter was studied by using the constrained optimization method. In addition to finding a optimal condition of the enzyme tablets, the application of sensitivity analysis studies to such problems was also illustrated. In order to get a stable preparations of the enzyme tablets, accelerated test of coating tablets was carried out in this study. the results are as follows. 1) The minimum disintegration time, such that the average tablet volume did not exceed 0.0154 cubic inch and the average friability value did not exceed 0.62%, was 6.6 minutes and then $Avicel{\circledR}$ and corn starch were 15.4% and 17.2%, respectively. 2) The multiple-correlation coefficients for the regression models of tablet hardness, friability, disintegration time and volume were with in the 95% confidence range. 3) According to the test results, calcium carboxymethyl cellulose can be used as a disintegrant instead of corn starch.

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Research on a Stability of Feedwater Control System after Stretched Power Uprate and Replacement Steam Generator for Ulchin Units 1&2 (울진1,2호기 출력최적화 및 증기발생기 교체가 주급수 제어계통 안정도에 미치는 영향연구)

  • Yoon, Duk-Joo;Kim, In-Hwan;Kim, Sang-Yeol
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.8 no.2
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    • pp.14-20
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    • 2012
  • Full load rejection capability of nuclear power plant depends primarily on steam dump capacity (SDCAP) and steam generator level control capability. Recently, Ulchin Units 1&2 have performed stretched power uprate (SPU) and replacement steam generator (RSG) projects, which increase the power by 4.5 percent. They change major design or operating parameters and especially reduces steam dump capacity at full power due to increase of the steam flow. The reduction of SDC after SPU results in degradation of heat removal capability in full load rejection transients. Therefore, we should perform evaluation to determine whether reactor trips occur in large load rejection transients. Uchin Units 1&2 have experienced full load rejection (FLR) three times from 2004 to 2010. Operating data from the plant occurrence of FLR at Ulchin Units 1&2 showed that steam generator (SG) level transients were limiting in point of reactor trip. However the plant had never reached reactor trip in the FLR and successfully continued in house load operation. The parameters and setpoints for the SG will be changed if the SG is replaced. Therefore, we evaluated the appropriateness of steam dump, main feedwater and steam generator water level control system preventing the plant from reactor trip in case of FLR by the parameter sensitivity study whether SG water level operated smoothly after SPU and RSG projects.

Optimum Design of a Coil Spring for Improving the Performance of a Spring -Operated Mechanism (스프링 조작기의 성능 개선을 위한 코일스프링의 최적 설계)

  • Lee, Dae Woo;Sohn, Jeong Hyun;Yoo, Wan Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.3
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    • pp.275-280
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    • 2016
  • In this study, a release test bed is designed to evaluate the dynamic behaviors of a coil spring. From the release tests, the dynamic behaviors of a coil spring are analyzed. A lumped parameter spring model was established for numerical simulation of a spring. The design variables of a coil spring are optimized by using the design of experiments approach. Two-level factorial designs are used for the design optimization, and the primary effects of the design variables are analyzed. Based on the results of the interaction analysis and design sensitivity analysis, the level of the design variables is rearranged. Finally, the mixed-level factorial design is used for the optimum design process. According to the optimum design of the opening spring, the dynamic performance of the spring-operated mechanism increases by 2.90.

Safety Assessment on the Human Intrusion Scenarios of Near Surface Disposal Facility for Low and Very Low Level Radioactive Waste (저준위 및 극저준위 방사성폐기물 표층처분시설의 인간침입 시나리오 안전평가에 대한 고찰)

  • Hong, Sung-Wook;Park, Sangho;Park, Jin Beak
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.14 no.1
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    • pp.79-90
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    • 2016
  • The second-stage near surface disposal facility for low and very low level radioactive waste's permanent disposal is to be built. During the institutional control period, the inadvertent intrusion of the general public is limited. But after the institutional control period, the access to the general public is not restricted. Therefore human who has purpose of residence and resource exploration can intrude the disposal facility. In this case, radioactive effects to the intruder should be limited within regulatory dose limits. This study conducted the safety assessment of human intrusion on the second-stage surface disposal facility through drilling and post drilling scenario. Results of drilling and post drilling scenario were satisfied with regulatory dose limits. The result showed that post-drilling scenario was more significant than drilling scenario. According to the human intrusion time and behavior after the closure of the facility, dominant radionuclide contributing to the intruder was different. Sensitivity analyses on the parameters about the human behavior were also satisfied with regulatory dose limits. Especially, manual redistribution factor was the most sensitive parameter on exposure dose. A loading plan of spent filter waste and dry active waste was more effective than a loading plan of spent filter waste and other wastes for the radiological point of view. These results can be expected to provide both robustness and defense in depth for the development of safety case further.

A Probabilistic Safety Assessment of a Pyro-processed Waste Repository (A-KRS 처분 시스템 확률론적 안전성 평가)

  • Lee, Youn-Myoung;Jeong, Jongtae
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.10 no.4
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    • pp.263-272
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    • 2012
  • A GoldSim template program for a safety assessment of a hybrid-typed repository system, called A-KRS, in which two kinds of pyro-processed radioactive wastes, low-level metal wastes and ceramic high-level wastes that arise from the pyro-processing of PWR nuclear spent fuels are disposed of, has been developed. This program is ready both for a deterministic and probabilistic total system performance assessment which is able to evaluate nuclide release from the repository and farther transport into the geosphere and biosphere under various normal, disruptive natural and manmade events, and scenarios. The A-KRS has been probabilistically assessed with 9 selected input parameters, each of which has its own statistical distribution for a normal release and transport scenario associated with nuclide release and transport in and around the repository. Probabilistic dose exposure rates to the farming exposure group have been evaluated. A sensitivity of 9 selected parameters to the result has also been investigated to see which parameter is more sensitive and important to the exposure rates.

A Sensitivity Study of the Number of Parcels to the Numerical Simulation of Sprinkler Sprays (통계적 액적군집수에 따른 스프링클러 분무해석의 민감도에 관한 연구)

  • Kim, Sung-Chan;Lee, Sang-Woo;Park, Won-Ju
    • Fire Science and Engineering
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    • v.23 no.1
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    • pp.48-54
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    • 2009
  • The present study has been performed to investigate the effect of statistical number of droplets on the simulation of the sprinkler spray using fire field model. In order to simulate the sprinkler spray characteristics, the present study uses NIST Fire Dynamics Simulator version 5.2. A group of Lagrangian particles with similar droplet characteristics, such as diameter, velocity, temperature and so on, is represented by parcel concept to decrease the total number of droplets tracked in the simulation. The present study introduces a new parameter to represent the ratio between real number of droplets and computational parcels. The dependency of the number of parcels on the fire suppression characteristics and spray patterns is quantitatively examined for different ratio between the real number of droplets and computational parcels.

Analysis of the Uncertainty of Compressive Forces Acting on the Patella by Using Multi-Body Modeling and Muscle Mechanics (다물체 모델링과 근의 특성을 이용한 무릎뼈에 가해지는 압력의 불확실성 추정 연구)

  • NamGoong, Hong;Yoo, Hong-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.7
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    • pp.785-790
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    • 2011
  • The goal of this study is to estimate the force acting on the knee joint in the human body by using the Hilltype muscle model based on a musculoskeletal model of the human lower extremity in the sagittal plane. For estimating the force applied, the human leg is modeled using multi-body modeling. This leg model comprises biarticular muscles acting on two joints of the upper and lower limbs, and the muscles include some of the major muscles such as the hamstring. In order to analyze the uncertainty of the applied forces acting on the knee joint, statistical distributions of human body, leg part, parameters are required and to obtain the parameter's statistical characteristic of the part sample survey method is employed. Finally, by using the sensitivity information of the parameters, the force acting on the knee joint can be estimated.