• 지질공학
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• 제9권1호
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• pp.1-15
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• 1999

여름철 집중강우시 발생하는 공주 송산리고분군의 누수 원인을 분석하기 위하여 인공함양시험을 실시하였다. 함양시험을 모사하는 2차원 불포화 지하수 유동 모델을 개발하고, 시험 중 측정한 관측정 수위와 함양량의 변화를 이용하여 모델변수의 보정을 수행하였으며 보정된 모델변수에 의하여 함양시험 모사를 실시하였다. 함양시험 및 모사 결과 고분군 누수현상의 주된 원인은 고분군 상부의 누수방지층에 발생한 균열을 통한 지하수의 직접적인 유입에 의한 것으로 분석되었다. 장기간 강우가 지속될 경우 고분군 북측의 원지반으로부터 불포화대를 통한 지하수의 유입 가능성이 존재하나 고분군 북측 벽체에 10% 내외의 유효포화도 증가만을 일으킬 것으로 정류상태 모사를 통하여 분석되었다. 따라서 고분군 누수 방지를 위한 대책으로는 트렌치에 의한 유도배수시설보다는 효과적인 누수방지층의 보강이 더 시급한 것으로 판단된다.

• Membrane and Water Treatment
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• 제9권3호
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• pp.137-146
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• 2018

Soil washing is one of the most frequently used remediation technologies for heavy metal-contaminated soils. Inorganic and organic acids and chelating agents that can enhance the removal of heavy metals from contaminated soils have been employed as soil washing agents. However, the toxicity, low removal efficiency and high cost of these chemicals limit their use. Given that humic substance (HS) can effectively chelate heavy metals, the development of an eco-friendly, performance-efficient and cost-effective soil washing agent using a nano-scale chelator composed of HS was examined in this study. Copper (Cu) and lead (Pb) were selected as target heavy metals. In soil washing experiments, HS concentration, pH, soil:washing solution ratio and extraction time were evaluated with regard to washing efficiency and the chelation effect. The highest removal rates by soil washing (69% for Cu and 56% for Pb) were achieved at an HS concentration of 1,000 mg/L and soil:washing solution ratio of 1:25. Washing with HS was found to be effective when the pH value was higher than 8, which can be attributed to the increased chelation effect between HS and heavy metals at the high pH range. In contrast, the washing efficiency decreased markedly in the low pH range due to HS precipitation. The chelation capacities for Cu and Pb in the aqueous phase were determined to be 0.547mmol-Cu/g-HS and 0.192mmol-Pb/g-HS, respectively.

• 한국실내디자인학회논문집
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• 제19권3호
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• pp.196-204
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• 2010

Human beings are having suffered from the unexpected climate changes which are caused by global warming leaded from air pollution. More than 3 billions of people will be forced to experience insufficient water in 2015. In Korea, over 70% of precipitation has been concentrating in Summer season. Furthermore, natural disasters has been occurred constantly all over the country. The unusual flood and drought have broken out not only victims but also, property damages. By the natural condition, the effective consuming and controlling system of water is going to be the core business field and constructing dams will be encouraged and promoted for the system. To convince the objectionable against the constructing dams, a dam exhibition center stands the very important position by being responsible for the presenting positive factors and highlighting the beneficial functions. The dam exhibition center is built as complex space combined by information center regarding water resources and visitor center for the community nearby the inundated area. Combined of the different purposes, the dam exhibition center can be confused to understand the concept and contents established in the space. To enhance the visitors' understanding contents of the dam exhibition center, the spatial composition and contents are being analyzed with existing centers and define the most effective exhibition methods between the spaces and visitors. This study will be the basic quantitative analysis data for the following design works those can get the better insight how to make visitors to get information and agreement of constructing dams effectively.

• 한국재료학회지
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• 제23권10호
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• pp.543-549
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• 2013

The purpose of this paper was to investigate the effect of a high-energy milling (HEM) process on the particle morphology and the correlation between a thermal treatment and tetragonal/monoclinic nanostructured zirconia powders obtained by a precipitation process. To eliminate chloride residue ions from hydrous zirconia, a modified washing method was used. It was found that the used washing method was effective in removing the chloride from the precipitated gel. In order to investigate the effect of a pre-milling process on the particle morphology of the precipitate, dried $Zr(OH)_4$ was milled using a HEM machine with distilled water. The particle size of the $Zr(OH)_4$ powder exposed to HEM reduced to 100~150 nm, whereas that of fresh $Zr(OH)_4$ powder without a pre-milling process had a large and irregular size of 100 nm~1.5 ${\mu}m$. Additionally, modified heat treatment process was proposed to achieve nano-sized zirconia having a pure monoclinic phase. It was evident that two-step calcining process was effective in perfectly eliminating the tetragonal phase, having a small average particle of ~100 nm with good uniformity compared to the sample calcined by a single-step process, showing a large average particle size of ~300 nm with an irregular particle shape and a broad particle size distribution. The modified method is considered to be a promising process for nano-sized zirconia having a fully monoclinic phase.

• 한국산림과학회지
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• 제94권6호
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• pp.481-487
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• 2005

이 연구에서는 지표화 중심의 산불확산예측 알고리즘을 기반으로 GIS 환경에서 운용이 가능한 지표화 확산예측모델을 개발하였다. 이 모델은 지형, 연료, 기상 등 산불환경인자를 분석하고 입력하는 부분과 시간에 따라 확산속도, 화선에서의 산불강도, 연소면적을 예측하는 지표화 확산예측 부분, 마지막으로 예측결과를 사용자에게 제시하는 출력 부분으로 구성되었다. 산불확산속도를 계산하기 위해서 산불행동에 영향을 미치는 산불환경인자중에서 지형인자는 경사, 기상인자는 풍속, 풍향, 실효습도를 고려하였다. 또한 연료인자는 수치임상도를 이용하여 연료깊이, 연료량, 소화습도를 계산할 수 있는 연료모듈을 개발하여 입력되도록 하였다. 연료습도는 실효습도, 최고온도, 강수량, 일일 적산량의 함수관계로 추정하였다. 모델을 2002년 청양에서 발생한 산불에 적용한 결과 확산속도에 대해 61%의 일치도를 보였다.

• 한국농공학회논문집
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• 제61권3호
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• pp.77-88
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• 2019

Drought is the recurrent natural disasters which harshly affect agricultural production and society in various parts in Bangladesh. Information on the spatiotemporal variability of drought events plays a vital role to take necessary action towards drought mitigation and sustainable development. This study aims to analyze the spatial and temporal variation of meteorological drought in Bangladesh during 1981-2015 using Effective Drought Index (EDI). Monthly precipitation data for 36 years (1980-2015) were obtained from 27 meteorological stations. Drought frequency (DF) and areal extent of drought were considered to investigate the spatiotemporal structure of drought. The DF analysis showed that the northern, southwestern and central regions of the country are comparatively vulnerable to meteorological drought. The frequency of drought in all categories has considerably increased during the recent five years from 2011 to 2015. Furthermore, the most significant increasing trend of the drought-affected area was found over the central region especially for pre-monsoon (March-May) season during this period while the decreasing trend of the affected area was found within the eastern region during the study period. To prevent and mitigate the damages of drought disasters in Bangladesh, agricultural and government managers should pay more attention to those regional drought events that occur in pre-monsoon season. The outcome of the present study can be used as explanatory data in building the strategies to drought monitoring and mitigation activities in Bangladesh.

• 한국미생물·생명공학회지
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• 제51권4호
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• pp.449-456
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• 2023

Sugar or dextrose increases the cost of production of xanthan gum by Xanthomonas campestris. Brewers' Spent Grain (BSG) was chosen as a source of fermentable sugars. BSG is a significant industrial by-product generated in large quantities from the breweries. Primarily used as animal feed due to its high fiber and protein content, BSG holds great potential as an economically and ecologically sustainable substrate for fermenting biomolecules. This study explores BSG's potential as a cost-effective carbon source for producing xanthan, utilizing Xanthomonas campestris NCIM 2961. An aqueous extract was prepared from BSG and inoculated with the bacterium under standard fermentation conditions. After fermentation, xanthan gum was purified using a standard protocol. The xanthan yield from BSG media was compared to that from MGYP media (control). The fermentation parameters, including pH, temperature, agitation and duration were optimized for maximum xanthan gum yield by varying them at different levels. Following fermentation, the xanthan gum was purified from the broth by alcoholic precipitation and then dried. The weight of the dried gum was measured. The obtained xanthan from BSG under standard conditions and commercial food-grade xanthan were characterized using FTIR. The highest xanthan yields were achieved at 32 ℃, pH 6.0, and 72 h of fermentation at 200 rpm using BSG media. The FTIR spectra of xanthan from BSG media closely resembled that of commercial food-grade xanthan. The results confirm the potential of BSG as a cost-effective alternative carbon source for xanthan production, thereby reducing production costs and solid waste.

• 한국산림과학회지
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• 제84권4호
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• pp.479-488
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• 1995

송이 발생(發生)의 제한인자(制限因子)를 파악(把握)하고 극복방안(克服方案)을 개발(開發)하기 위(爲)하여 18개(個) 주요(主要) 송이산지(産地)의 생산량(生産量)과 송이 발생(發生)에 관여(關與)하는 주요(主要) 기상인자(氣象因子)(월별(月別) 강수량(降水量), 상대습도(相對濕度) 평균기온(平均氣溫), 최고(最高) 최저기온(最低氣溫), 지중온도(地中溫度), 일조율(日照率)의 관계(關係)을 지난 17년간(年間)(1978-1994)의 자료(資料)를 이용(利用)하여 분석(分析)하였다. 송이 발생(發生)에 가장 큰 영향(影響)을 미치는 인자(因子)는 지역별(地域別)로 다르지만 대체로 송이 발생기(發生期)인 9월(月)의 기상(氣象)이었으며 각(各) 인자(因子)들의 중요도(重要度)는 지역별(地域別)로 다르게 나타났다. 이 중(中)에서 1% 유의수준(有意水準)에서 $$r^2{\geq_-}0.41$$를 나타낸 인자(因子)는 9월(月) 평균최저기온(平均最低氣溫)으로 이 온도(溫度)가 높을수록 송이 발생량(發生量)이 많았으며, 이런 현상(現象)이 있는 지역(地域)은 영덕(盈德), 울진(蔚珍), 삼척(三陟), 봉화(奉化) 등(等) 9개(個) 지역(地域)이었다. 이들 지역(地域)에서는 식생정리(植生整理)를 통해 임내(林內)에 햇빛이 많이 들어 오도록 하여 균환(菌環) 주변(周邊)의 온도(溫度)를 높이면 송이 증수(增收)에 효과적(效果的)일 것으로 예상(豫想)되었다. 9월(月) 강수량(降水量)이 $$r^2{\geq_-}0.41$$인 지역(地域)은 남원(南原), 문경(聞慶), 상주지역(尙州地域)이었고, 이 지역(地域)에서는 송이 발생시기(發生時期)에 균환주변(菌環周邊)에 관수(灌水)하는 것이 효과(效果)를 거둘 것으로 기대(期待)되었다. 1994년(年)에는 가뭄으로 인(因)하여 1993년(年)에 버금가는 흉년(凶年)을 맞이하였는데, 문경(聞慶)과 거창지역(居昌地域)에서는 관수처리(灌水處理)를 통해 가뭄을 극복(克服)하여 송이를 증산(增産)할 수 있는 가능성(可能性)을 확인(確認)할 수 있었다.

• 한국환경과학회지
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• 제17권6호
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• pp.601-609
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• 2008

In this study for the development of area due to the increasing of industry, population and spreading of urbanization is rapidly increasing but about seventy percent of our nation's areas consists of the mountainous districts. In such case, when those areas have the heavy rains break, they are washed away by a fast-flowing stream of a valley and overflowed. Thus it could result on human life and property damage and also the widespread of flood damage in the downstream area. To decrease those damage, the construction of flood control reservoir is necessary. This research was aim to construct the flood runoff models of a mountainous small district and to determine the probability rainfall by analyzing precipitation. The study also examined the effects of location and size of flood control reservoir on flood reduction. The result showed that the construction of detention basin was an effective way to ensure the safety of flood control and multiple detention basin had superior result for reducing amount of runoff in the down stream area than the single detention basin.

• 한국재료학회지
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• 제24권9호
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• pp.488-494
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• 2014

The effect of tungsten (W) addition on the hardenability of low-carbon boron steels was investigated using dilatometry, microstructural observations and secondary ion mass spectroscopy. The hardenability was discussed with respect to transformation behaviour aspects depending on the segregation and precipitation of boron at austenite grain boundaries. A critical cooling rate producing a hardness corresponding to 90 % martensite structure was measured from a hardness distribution plot, and was used as a criterion to estimate hardenability at faster cooling rates. In the low-carbon boron steel, the addition of 0.50 wt.% W was comparable to that of 0.20 wt.% molybdenum in terms of critical cooling rate, indicating hardenability at faster cooling rates. However, the addition of 0.50 wt.% W was not more effective than the addition of .0.20 wt.% molybdenum at slower cooling rates. The addition of 0.20 wt.% molybdenum completely suppressed the formation of eutectoid ferrite even at the slow cooling rate of $0.2^{\circ}C/s$, while the addition of 0.50 wt.% W did not, even at the cooling rate of $1.0^{\circ}C/s$. Therefore, it was found that the effect of alloying elements on the hardenability of low-carbon boron steels can be differently evaluated according to cooling rate.