• Structural Engineering and Mechanics
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• 제64권4호
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• pp.413-426
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• 2017

Probabilistic methods are used in engineering where a computational model contains random variables. The proposed method under development: Direct Optimized Probabilistic Calculation (DOProC) is highly efficient in terms of computation time and solution accuracy and is mostly faster than in case of other standard probabilistic methods. The novelty of the DOProC lies in an optimized numerical integration that easily handles both correlated and statistically independent random variables and does not require any simulation or approximation technique. DOProC is demonstrated by a collection of deliberately selected simple examples (i) to illustrate the efficiency of individual optimization levels and (ii) to verify it against other highly regarded probabilistic methods (e.g., Monte Carlo). Efficiency and other benefits of the proposed method are grounded on a comparative case study carried out using both the DOProC and MC techniques. The algorithm has been implemented in mentioned software applications, and has been used effectively several times in solving probabilistic tasks and in probabilistic reliability assessment of structures. The article summarizes the principles of this method and demonstrates its basic possibilities on simple examples. The paper presents unpublished details of probabilistic computations based on this method, including a reliability assessment, which provides the user with the probability of failure affected by statistically dependent input random variables. The study also mentions the potential of the optimization procedures under development, including an analysis of their effectiveness on the example of the reliability assessment of a slender column.

• 대한조선학회지
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• 제20권2호
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• pp.1-20
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• 1983

In this paper design criteria for semi-submersibles, effective at the stage of basic design, are reviewed first generally. Thereafter an extensive study is focussed on essential problematic areas such as design load, heaving motion, overall structural analysis and welding technique. The necessity for this kind of research is apparent in the light of the fact that ocean exploration and exploitation becomes extended to deeper ocean and that semi-submersibles are the most favorite unit for operation under this environment. In some sense principles in naval architecture are indeed applicable to the design of semi-submersible. However, because of the difference in geometry between ships and semi-submersibles, there are significant deviations in design method. A thorough discussion is made on particular behaviours of a semi-submersible in stability, wave load, motion characteristics and structural responses. Then some calculation-procedures and design guidelines are tentatively proposed. A numerical calculation for a semi-submersible Sedco 708 is exemplified for better understanding of the concept. The structure has 4 main and another 4 secondary stabilizing columns with catamaran-type lower hull. In this example design condition is supposed to be 28m wave height, 90 knots wind speed for survival condition and seastate 6 for operational condition in water of 100m depth. The numerical result implies that the actual design of this model can be assessed close to optimum. Further intensive research is strongly required in the subject fields of dynamic stability, rational evaluation of wave load statistical basis for fatigue life judgement.

• 한국대기환경학회지
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• 제27권4호
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• pp.405-415
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• 2011

The objective of this study was to compare greenhouse gas emissions from road transportation by calculation methods (Tier 1, Teir 2, and Tier 3). Tier 1 based on 2006 IPCC guidelines default emission factor and amount of fuel consumption. The Tier 2 approach is the same as Tier 1 except that country-specific carbon contents of the fuel sold in road transport are used. Tier 2 based on emission factor of guidelines for local government greenhouse gas inventories (Korea Environment Corporation), the fuel consumption per one vehicle, and the registered motor vehicles. The Tier 3 approach requires detailed, country-specific data to generate activity-based emission factors for vehicle subcategories (National Institute of Environmental Research) and may involve national models. Tier 3 calculates emissions by multiplying emission factors by vehicle activity levels (e.g., VKT) for each vehicle subcategory and possible road type. VKT was estimated by using GIS road map and traffic volume of the section. The GHG average emission rate by the Tier 1 was 728,857 $tonCO_2eq$/yr, while Tier 2 and Tier 3 were 864,757 $tonCO_2eq$/yr and 661,710 $tonCO_2eq$/yr, respectively. Tier 3 was underestimated by 10.1 and 20.7 percent for the GHG emission observed by Tier 1 and Tier 2, respectively. Based on this study, we conclude that Tier 2 is reasonable GHG emissions than Tier 1 or Tier 3. But, further study is still needed to accurate GHG emission from Tier 3 method by expanding the traffic survey area and developing the model of local road traffic.

• Journal of Nutrition and Health
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• 제16권4호
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• pp.296-302
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• 1983

국가적(國家的) 차원에서의 국민영양소요양(國民營養所要量)을 확립하는데 중요한 지표(指標)가 되는 한국인(韓國人) 평균1인1일당(平均1人1日當) 영양소요양(營養所要量)설정의 필요성에 의하여, 1980년도(年度) 경제기획원인구(經濟企劃院人口)센서스 자료(資料)와 FAO한국협회(韓國協會)가 1980년(年) 제(第)3 차 (次) 개정(改定)한 한국인영양권장양으로부터 한국인(韓國人) 평균(平均)1인(人)1일당(日當) 영양소요양(營養所要量)을 계산(計算)하였다. 즉 영양소별(營養素別) 평균(平均)1인(人)1일당(日當) 영양소요양(營養所要量)은 에너지 2,200 kcal, 단백질(蛋白質) 70 g, 칼슘 0.72 g, 철(鐵) 14 mg, 비타민 A 1,900 IU, 비타민 C 50 mg, 비타민$B_{1}$ 0.9 mg, 비타민 $B_{2}$ 1.2 mg 그리고 나이아신당양(當量)은 15 mg이었다.

• 한국수산과학회지
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• 제40권1호
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• pp.39-49
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• 2007

Species competition among the toxic dinoflagellates Alexandrium tamarense and Gymnodinium catenatum and the diatom Skeletonema costatum was simulated using a mathematical model. Prior to the model simulation competition experiments using the three species were conducted to obtain data for validation by the simulation model. S. costatum dominated at a density of ${\sim}10^{4}\;cells/mL$ compared to the other species in the medium with dissolved inorganic phosphorus (DIP). The growth of S. costatum was also stimulated by the addition of dissolved organic phosphorus (DOP), such as uridine-5-monophosphate (UMP) or glycerophosphate (Glycero-P), although this species is unable to take up DOP. This implies that the growth of S. costatum may be supported by DIP, which is hydrolyzed by alkaline phosphatase produced from A. tamarense and G. catenatum. The species competition model was run assuming the environmental conditions of northern Hiroshima Bay, Japan, during spring and summer. G. catenatum increased in cell density and neared the level of S. costatum at the end of the calculation. In the sensitivity analyses by means of doubling and halving parameters, depleted DIP had little effect on the cell density of G. catenatum. However the growth of A. tamarense and S. costatum was significantly affected by changes in the parameter values. These results indicate that if DIP depletion is ongoing, species that have a large phosphate pool in their cells, such as G. catenatum, will predominate in the community.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.77-79
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• 1996

The model interrupters of $SF_6$ gas electromagnetic contactor whose ratings are 7.2kV, 4.0kA have been designed and manufactured on the basis of theoretical and computational analysis for its development. The eddy current analysis, the magnetic field analysis and the calculation of the rotational force on arcs have been conducted using FLUX2D package. The short circuit current interrupting tests have been conducted for the model interrupters using the simplified synthetic testing facility in KERI. The results show that the model interrupters have sufficient interrupting capability and the new design concept is prefer for good interrupting performance.

• 한국분무공학회지
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• 제1권4호
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• pp.24-31
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• 1996

This study addresses the behavior characteristics of diesel spray injected on the impinging disk with the room temperature. The models of impinging spray are the stick, the reflect and the wall jet model In the initiative of the fuel injection the impinging spray was the reflect model. because the momentum of droplets was very large. This model developed to the wall jet model according to the time approaches. On the low temperature disk the fuel film was made by the attachment of the droplets with low Weber number. The thickness of impinging spray was increased when the disk approached to the nozzle tip. Mathematical analysis for calculation with the behavior of impinging spray have to consider the reflecting effect and the influence of the fuel film.

• 한국전산유체공학회지
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• 제7권4호
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• pp.1-7
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• 2002

The phase-change transformation processes are relevant in many engineering applications. In particular, this phenomenon plays an important role in the extraction and fabrication operations in the metallurgical industry. The control of the heat transfer and fluid flow patterns is important to achieve casting quality and competitive production times. In the present study, a simple finite-element algorithm is developed for solid-liquid phase change problems. Natural convection in the liquid phase due to the temperature dependency of water density is considered by a numerical model. The predictions are compared with measurements by the particle image velocimetry(PIV). to show that the calculation results are in good agreement with the experiment results.

• Journal of Magnetics
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• 제3권4호
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• pp.120-122
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• 1998

The higher order harmonic components of magnetostriction during ac magnetization in 3% SiFe are measured as a function of the magnetizing angle respect to [001] axis using a constructed laser interferometry. The magnetostriction with magnetizing angle from [001] axis agrees ith the calculation based on domain reorientation. The relative amplitudes of odd and even harmonics respectively for magnetic induction and magnetostriction decrease with the order of harmonics, accompanying the contraction of the amplitudes. The contraction of harmonics order of magnetostriction harmonics is shown to be the even number times of that of magnetic induction.

• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.2931-2936
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• 2013

This paper presents results for the calculation of transport properties of noble gases (He, Ne, Ar, Kr, and Xe) at 273.15 K and 1.00 atm using equilibrium molecular dynamics (EMD) simulations through a Lennard-Jones (LJ) intermolecular potential. We have utilized the revised Green-Kubo formulas for the stress (SAC) and the heat-flux auto-correlation (HFAC) functions to estimate the viscosities (${\eta}$) and thermal conductivities (${\lambda}$) of noble gases. The original Green-Kubo formula was employed for diffusion coefficients (D). The results for transport properties (D, ${\eta}$, and ${\lambda}$) of noble gases at 273.15 and 1.00 atm obtained from our EMD simulations are in a good agreement with the rigorous results of the kinetic theory and the experimental data. The radial distribution functions, mean square displacements, and velocity auto-correlation functions of noble gases are remarkably different from those of liquid argon at 94.4 K and 1.374 $g/cm^3$.