• IE interfaces
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• v.17 no.spc
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• pp.90-96
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• 2004

In this paper, we consider the joint replenishment problem of a one-warehouse, n-retailer system. We introduce a joint replenishment and delivery strategy of a warehouse and develop a mathematical model based on the proposed strategy. Two efficient algorithms are presented and compared using numerical examples. The proposed strategy is compared with the common cycle strategy for 1,600 randomly generated problems, and has been proven to be superior to the common cycle strategy.

• Korean Journal of Mathematics
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• v.29 no.3
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• pp.577-580
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• 2021

For a finite simplicial graph 𝚪, let G(𝚪) denote the right-angled Artin group on the complement graph of 𝚪. For path graphs P_k, cycle graphs C_ℓ and complete bipartite graphs K_n,m, this article characterizes the embeddability of G(K_n,m) in G(P_k) and in G(C_ℓ).

• Clean Technology
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• v.24 no.1
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• pp.9-14
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• 2018

In this study, Material life cycle evaluation was performed to analyze the environmental impact characteristics of TiN-Zr membrane manufacturing process. The software of MLCA was Gabi. Through this, environmental impact assessment was performed for each process. Transition metal nitrides have been researched extensively because of their properties. Among these, TiN has the most attention. TiN is a ceramic materials which possess the good combination of physical and chemical properties, such as high melting point, high hardness, and relatively low specific gravity, high wear resistance and high corrosion resistance. With these properties, TiN plays an important role in functional materials for application in separation hydrogen from fossil fuel. Precursor TiN was synthesized by sol-gel method and zirconium was coated by ball mill method. The metallurgical, physical and thermodynamic characteristics of the membranes were analyzed by using Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDS), X-ray Diffraction (XRD), Thermo Gravimetry/Differential Thermal Analysis (TG/DTA), Brunauer, Emmett, Teller (BET) and Gas Chromatograph System (GP). As a result of characterization and normalization, environmental impacts were 94% in MAETP (Marine Aquatic Ecotoxicity), 2% FAETP (Freshwater Aquatic Ecotoxicity), 2% HTP (Human Toxicity Potential). TiN fabrication process appears to have a direct or indirect impact on the human body. It is believed that the greatest impact that HTP can have on human is the carcinogenic properties. This shows that electricity use has a great influence on ecosystem impact. TiN-Zr was analyzed in Eco-Indicator '99 (EI99) and CML 2001 methodology.

• Journal of the Semiconductor & Display Technology
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• v.2 no.2
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• pp.5-8
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• 2003

In this study, as Cu diffusion barrier, tantalum nitrides were successfully deposited on Si(100) substrate and $SiO_2$ by plasma assisted atomic layer deposition(PAALD) and thermal ALD, using pentakis (ethylmethlyamino) tantalum (PEMAT) and NH$_3$ as precursors. The TaN films were deposited at $250^{\circ}C$ by both method. The growth rates of TaN films were 0.8${\AA}$/cycle for PAALD and 0.75${\AA}$/cycle for thermal ALD. TaN films by PAALD showed good surface morphology and excellent step coverage for the trench with an aspect ratio of h/w -1.8:0.12 mm but TaN films by thermal ALD showed bad step coverage for the same trench. The density for PAALD TaN was 11g/cmand one for thermal ALD TaN was 8.3g/$cm^3$. TaN films had 3 atomic % carbon impurity and 4 atomic % oxygen impurity for PAALD and 12 atomic % carbon impurity and 9 atomic % oxygen impurity for thermal ALD. The barrier failure for Cu(200 nm)/TaN(10 nm)/$SiO_2$(85 nm)/ Si structure was shown at temperature above $700^{\circ}C$ by XRD, Cu etch pit analysis.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.617-617
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• 1989

This paper deals with a fatigue life prediction of a surface crack based on the experimentally obtained relationship between surface crack length ratio $a/a_{f}$ and cycle ratio $N/N_{f}$ using micro computer. Firstly $a/a_{f}$-$N/N_{f}$ curves obtained from experimental tests, were assumed as three curves UC(the upper limit curve), LC(the lower limit curve) and MC(the middle curve), and these were utilized to predict the fatigue life. Comparing the calculated values which represent the characteristics of crack growth behaviors from the three assumed curves with the experimental ones, it has been found that in the stable crack growth region, they coincide reasonably well each other. And the differences between the fatigue lives obtained from the assumed curves and the experimental fatigue life did not exceed 20%. Using the characteristics of $a/a_{f}$-$N/N_{f}$ curves, it is possible to predict the da/dN-Kmax curves and the S-$N_{f}$ curves.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.14-19
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• 2002

In this study, as Cu diffusion barrier, tantalum nitrides were successfully deposited on Si(100) substrate and SiO2 by plasma assisted atomic layer deposition(PAALD) and thermal ALD, using pentakis (ethylmethlyamino) tantalum (PEMAT) and $NH_3$ as precursors. The TaN films were deposited on $250^{\circ}$C by both method. The growth rates of TaN films were $0.8{\AA}$/cycle for PAALD and $0.75{\AA}$/cycle for thermal ALD. TaN films by PAALD showed good surface morphology and excellent step coverage for the trench with an aspect ratio of h/w - $1.8 : 0.12 \mu\textrm{m}$ but TaN films by thermal ALD showed bad step coverage for the same trench. The density for PAALD TaN was $11g/\textrm{cm}^3$ and one for thermal ALD TaN was $8.3g/\textrm{cm}^3$. TaN films had 3 atomic % carbon impurity and 4 atomic % oxygen impurity for PAALD and 12 atomic % carbon impurity and 9 atomic % oxygen impurity for thermal ALD. The barrier failure for Cu(200nm)/TaN(l0nm)/$SiO_2(85nm)$/Si structure was shown at temperature above $700^{\circ}$C by XRD, Cu etch pit analysis.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.306-314
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• 2015

This paper examines the difference in the value of the nuclear fuel cycle cost calculated by the deterministic and probabilistic methods on the basis of an equilibrium model. Calculating using the deterministic method, the direct disposal cost and Pyro-SFR (sodium-cooled fast reactor) nuclear fuel cycle cost, including the reactor cost, were found to be 66.41 mills/kWh and 77.82 mills/kWh, respectively (1 mill = one thousand of a dollar, i.e., $10^{-3}$ $). This is because the cost of SFR is considerably expensive. Calculating again using the probabilistic method, however, the direct disposal cost and Pyro-SFR nuclear fuel cycle cost, excluding the reactor cost, were found be 7.47 mills/kWh and 6.40 mills/kWh, respectively, on the basis of the most likely value. This is because the nuclear fuel cycle cost is significantly affected by the standard deviation and the mean of the unit cost that includes uncertainty. Thus, it is judged that not only the deterministic method, but also the probabilistic method, would also be necessary to evaluate the nuclear fuel cycle cost. By analyzing the sensitivity of the unit cost in each phase of the nuclear fuel cycle, it was found that the uranium unit price is the most influential factor in determining nuclear fuel cycle costs.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.51-56
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• 1999

Fatigue crack propagation rates and characteristics of the SA516-70 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $10^{\circ}C$ and low temperature ranges of $-10^{\circ}C,\;-30^{\circ}C,\;-50^{\circ}C,\;and\;-70^{\circ}C$ with stress ratio of R=0.05. The obtained experimental results are as follows; 1) In the logarithmic relationship between the fatigue crack propagation rate(da/dN) and stress intensity factor K, the linear relationship was obtained up to da/dN > $8{\times}10^3$ mm/cycle in the same of room temperature, but in low temperature case, the relationship was extended to the range of low crack propagation rate. 2) The lower limit stress intensity factor of SA516-70 ${\Delta}K_{th}\;was\;23MPa\sqrt{m}$ and in the case of low temperature $-50^{\circ}C\;and\;-70^{\circ}C$, the crack propagation rate da/dN which showed a linear relation, reached rapidly to the ${\Delta}K_{th}$. As the results, the crack propagation rates of $-50^{\circ}C\;and\;-70^{\circ}C$ were lower than that of room temperature and according to the testing temperature the rates were decreased rapidly to the ${\Delta}K_{th}$. 3) On the relationship between the stress intensity factor ${\Delta}K$ and the track propagation cycle, the stress intensity factors of low cycle region was rapidly increased at low temperature, but ${\Delta}K$ was increased rapidly at room temperature of high cycle. 4) On the relationship between the fatigue crack propagation rate and cycle, the fatigue crack propagation rate showed higher gradient in the room temperature than the low temperature due to the increment in ductility at low temperature.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.240-245
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• 2000

Fatigue crack propagation rates and characteristics of the SA516-60 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $25^{\circ}C$ and low temperature ranges of $10^{\circ}C,\; -10^{\circ}C,\; -30^{\circ}C,\; -50^{\circ}C, \;and\; -70^{\circ}C4 with stress ratio of R=0.05. The obtained experimental results are as follows; 1) In the logarithmic relationship between the fatigue crack propagation rate(da/dN) and stress intensity factor K, the linear relationship was obtained up to da/dN 〉$8\times10^{-3}$/mm/cycle in the same of room temperature, but in low temperature case, the relationship was extended to the range of crack propagation rate. 2) The lower limit stress intensity factor of SA516-60 $\DeltaK_{th}$ was 15.8MPa and in the case of low temperature $-50^{\circ}C\; and\; -70^{\circ}C$, the crack propagation rate da/dN which showed a linear relation, reached rapidly to the $\DeltaK_{th}$/. As the results, the crack propagation rates of $-50^{\circ}C\; and\; -70^{\circ}C$ were lower than that of room temperature and according to the testing temperature the rates were decreased rapidly to the $\DeltaK_{th}$/. 3) On the relationship between the stress intensity factor $\DeltaK$ and the crack propagation cycle, the stress intensity factors of low cycle region was rapidly increased at low temperature, but $\DeltaK$ was increased rapidly at room temperature of high cycle. 4) On the relationship between the fatigue crack propagation rate and cycle, the fatigue crack propagation rate showed higher gradient in the room temperature than the low temperature due to the increment in ductility at low temperature.

• Nuclear industry
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• no.8
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• pp.22-29
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• 1978