• Environmental Engineering Research
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• 제25권3호
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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.

• 한국터널지하공간학회 논문집
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• 제20권1호
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• pp.39-53
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• 2018

일반적으로 터널 내 총환기저항계수는 입출구 손실계수, 벽면마찰계수 그리고 급격한 확대나 축소단면 등에 의해 발생하는 부차적 손실계수의 총합으로 구성된다. 개통 전 터널의 경우는 가동 중인 환기팬을 중단하게 되면, 터널 내 풍속은 총환기저항력에 의해 감소하는 현상이 나타난다. 즉, 속도감쇄법은 개통 전 터널에서 비교적 안정적이면서도 손쉽게 터널 내 벽면마찰계수를 추정하는 방법이다. 그러나 기존의 선행연구에서 환기팬의 가동을 중단 후 수렴되는 풍속이 음수일 경우는 속도감쇄법에 따른 벽면마찰계수의 추정이 곤란한 특성이 있다. 반면 교통환기력이 작용하는 공용 중인 터널에서는 좀더 복잡한 과정을 거치지만, 합리적인 벽면마찰계수를 추정할 수 있다. 본 연구에서는 교통환기력의 측정변수를 최소화할 수 있는 방법을 제안하였고, 공용 중 터널에 적용할 수 있는 방법을 고찰하였다. 또한 환기팬 정지 후 터널 내 풍속이 감소하는 동안에 외부 자연풍의 급격한 변화가 발생하여도 교통환기력이 일정할 경우에 대하여, 교통환기력의 증분을 계산할 수 있는 방법과 터널 내 벽면마찰계수를 추정할 수 있도록 동적 시뮬레이션이 가능한 프로그램 로직을 개발하였다.

• 한국조경학회지
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• 제25권3호
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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.

• 대한수학회지
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• 제55권6호
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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.

• 상하수도학회지
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• 제17권4호
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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.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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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.

• 한국방사선학회논문지
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• 제17권7호
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• pp.1075-1089
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• 2023

핵감식은 국제사회에서 핵물질 통제 및 핵비확산 검증에 필수적인 부분으로 인식되고 있다. 핵감식을 위한 연대추정은 붕괴계열 특성 및 베이트만 방정식을 기반으로 핵물질의 정제 및 생산시기를 추정한다. 연대추정을 위한 요소 중 붕괴상수와 핵종 수는 분석이나 반복 실험을 통해 도출된 통계로 불확도를 가지기 때문에 연대추정의 결과도 불확도를 가진다. 본 연구는 기존의 베이트만 방정식 기반의 연대추정 불확도 계산의 한계를 극복하기 위해 전산모사를 통한 불확도 계산 알고리즘을 연구하였다. 불확도 계산 결과 기존 불확도 계산 방법과 동등한 수준의 결과가 나타났으며, 기존의 한계를 극복하여 2세대 이상의 불확도 계산이 가능하였고 불확도 계산 중 붕괴상수의 과소평가도 개선되었다.

• Journal of applied mathematics & informatics
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• 제19권1_2호
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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.

• 한국항만경제학회지
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• 제19권2호
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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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• 제39권2호
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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.