• Environmental Engineering Research
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• v.25 no.3
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• pp.374-383
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• 2020

Landfill gas (LFG) emissions from a given amount of landfill waste depend on the carbon flows in the waste. The objective of this study was to more accurately estimate the first-order decay parameters through methane (CH₄) and carbon flow balances based on the analysis of a full-scale landfill with long-term data and detailed field records on LFG and leachate. The carbon storage factor for the case-study landfill was 0.055 g-degradable organic carbon (DOC) stored per g-wet waste and the amounts of DOC lost with the leachate were less than 1.3%. The appropriate CH₄ generation rate constant (k) for bulk waste was 0.24 y-1. The the CH₄ generation potential (L0) values ranged 33.7-46.7 m3-CH₄ Mg-1, based on the fraction of DOC that can decompose (DOCf) value of 0.40. Results show that CH4 and carbon flow balance methods can be used to estimate model parameters appropriately and to predict long-term carbon emissions from landfills.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.39-53
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• 2018

Generally, the total ventilation resistance coefficient in a tunnel consists of inlet/outlet loss coefficient, wall friction coefficient, and other loss coefficient caused by sudden expansion and contraction of cross-section, etc. For the tunnel before opening, when the running ventilation fan is stopped, the wind speed in the tunnel is reduced by the total ventilation resistance drag. The velocity decay method is comparatively stable and easy to estimate the wall friction coefficient in the pre-opening tunnel. However, the existing study reported that when the converging wind speed is a negative value after the ventilation fan stops, it is difficult to estimate the wall friction coefficient according to the velocity decay method. On the other hand, for the operating tunnel in which the piston effect acts, a more complex process is performed; however, a reasonable wall friction coefficient can be estimated. This paper aims at suggesting a method to minimize the measurement variables of the piston effect and reviewing a method that can be applied to the operating tunnel. Also, in this study, a new method has been developed, which enables to calculate an variation of the piston effect if the piston effect is constant with a sudden change of external natural wind occurring while the wind speed in the tunnel decreases after the ventilation fan stops, and a programming logic has been also developed, which enables dynamic simulation analysis in order to estimate the wall friction coefficient in a tunnel.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.3
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• pp.1-11
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• 1997

This study aims to estimate the relative importance of quality management items through the defect analysis in the landscape construction process. The RIQMI are decided by the defect coefficient and it's cause weight. The defect items in the landscape construction process were classified by 56 items based on the classification form of '96 landscape architectural construction standard and the cause pattern were categorized 4 types as design, material, construction, and environment factors. To analyze the defect coefficient and the aucse weight by defect, the researcher surveyed the questionnaires on the 103 engineers and the 31 experts on the landscape architectural construction. The result of this study are as follows. The relative importance by facilities pattern turn out to be much higher construction, material fator than design. environment factor in wood facilities, paving facilities, and steel facilities, the RIQMI is very high in timber crack, timber vending, faulty of timber against decay, welding faulty of steel facilities in material factor, and timber crack, faulty of timber against decay, finish faulty of steel facilities, welding faulty of steel facilities in construction factor.

• Journal of the Korean Mathematical Society
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• v.55 no.6
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• pp.1423-1433
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• 2018

This paper is concerned about several quasilinear elliptic systems with m-Laplacians. According to the Liouville theorems of those systems on ${\mathbb{R}}^n$, we obtain the singularity estimates of the positive $C^1$-weak solutions on bounded or unbounded domain (but it is not ${\mathbb{R}}^n$ and their decay rates on the exterior domain when ${\mid}x{\mid}{\rightarrow}{\infty}$. The doubling lemma which is developed by Polacik-Quittner-Souplet plays a key role in this paper. In addition, the corresponding results of several special examples are presented.

• Journal of Korean Society of Water and Wastewater
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• v.17 no.4
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• pp.510-518
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• 2003

The fluoride work management of water supply conveyance has been recommending by the WHO to prevent of tooth decay. Fluoridation of public water supplies has been practiced since 1945. The present approximately 67 countries reported community water fluoridation benefiting many cities. At our country, Fluoridation began in 1981 in Chongiu and Jinhea. In 2002, approximately 40 cities have large populations consuming fluoridated water. But Chongiu stopped fluoridation water works. Few public health measures have been accorded greater clinical and laboratory research, epidemiological study, clinical trials, and public attention than has water fluoridation. In this study, chemical analysis of Sodium Silicofluoride and Fluoride Feed Equipment analyzed. And this study proposed to Fluoride concentration experimental (lab. and field exp.), economics analysis, prevention effect. This study can be decided on the concentration of fluoride injection in Water Fluoridation. Hereafter, this study will be useful in safety and economics of Water Fluoridation in the future.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.59-62
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• 2003

We fabricated two HTS closed coils by using resistive-joint method and the joint resistance of the coil was estimated by field decay technique at 77 K. In addition, we used the Runge-kutta method for the numerical analysis to estimate the decay properties. The joint resistances were evaluated as a function of critical current of HTS closed coil and external field strength of excitation coil. It was observed that joint resistance was independent of critical current and external field strength. It was estimated that joint resistance was 8.0$\times$10$^{-9}$ $\Omega$ to 11.9$\times$10$^{-9}$ $\Omega$ for coils of contact length for 7 cm.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1075-1089
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• 2023

Nuclear forensics is an essential part of nuclear material control and nuclear non-proliferation verification. Radiochronometry for nuclear forensics is used to estimate the timing of refinement and production of nuclear materials based on decay chain characteristics and the Bateman equation. The results of radiochronometry have uncertainties because the decay constant and number of nuclides are statistics derived from analyses or repeated experiments and involve uncertainties. The aim of this study was to develop an uncertainty calculation algorithm by performing computational simulation to overcome the limitations of the existing uncertainty calculation method for radiochronometry based on the Bateman equation. The results of the proposed uncertainty calculation algorithm were comparable to those of the existing method. The algorithm allowed for more than two generations of uncertainty calculations and mitigated the underestimation of the decay constant during the uncertainty calculation.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.385-395
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• 2005

A finite element scheme is considered for the viscous Cahn-Hilliard equation with the nonconstant gradient energy coefficient. The scheme inherits energy decay property and mass conservation as for the classical solution. We obtain the corresponding error estimate using the extended Lax-Richtmyer equivalence theorem.

• Journal of Korea Port Economic Association
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• v.19 no.2
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• pp.55-67
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• 2003

The purpose of this study is to estimate and forecast the marine trading volumes based on the structural model. We employ GPH cointegration test since the structural model must be stationary to get the accurate predicted values. The empirical results show that our model is stationary. This paper also applies variance decompositions and impulse-response functions to the structural model composed of exchange rate, domestic industrial activity, and world business. The results indicate that while both loading and unloading volumes respond positively to the shocks in income and then decay very slowly, their responses are different to the shocks in exchange tate.

• Nuclear Engineering and Technology
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• v.39 no.2
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• pp.143-148
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• 2007

Spent nuclear fuel generated at nuclear power plants must be safely stored during interim storage periods. A dry storage cask to safely store the spent nuclear fuel should be able to adequately emit the decay heat from the spent nuclear fuel. Therefore, heat removal tests using a half scale dry storage cask have been performed to estimate the heat transfer characteristics of a dry storage cask under normal, off-normal, and accident conditions. In the normal condition, the heat transfer rate to an ambient atmosphere by convective air through a passive heat removal system reached 83%. Accordingly, the passive heat removal system is designed well and works adequately. In the off-normal condition, the influence of a half blockage in the inlet on the temperature appears minimal. In the accident condition, the temperature rose for 12 hours after the accident, but the temperature rise steadied after 36 hours.