• 한국지반환경공학회 논문집
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• 제20권4호
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• pp.17-21
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• 2019

국내 한랭지역의 경우 고속도로터널 및 일반도로터널에서 발생하는 동결피해 사례는 조사 및 보고되고 있지만, 이에 대한 방안대책은 미흡한 상황이다. 한랭지역의 경우 영상권을 유지하는 다른 지역들과는 달리 평균온도가 영하로 떨어지는 지역이며, 동일지역 터널 내에서도 기온이 낮은 입출구에서 손상이 좀 더 발생하는 것으로 조사 되었다. 터널 라이닝의 온도저하를 방지하기 위하여 동절기에 라이닝의 온도를 강제로 상승시킬 수 있는 발열체를 제작하였다. 발열체는 실규모 터널의 라이닝에 부착하여 발열체의 열에 의한 터널 라이닝 주변의 온도변화를 측정하였다. 연구결과 발열체의 발열에 의해 라이닝의 온도상승 정도를 확인하였으며, 일정시간이 경과하면 라이닝의 온도상승이 수렴하는 것으로 나타났다. 이러한 결과를 활용하여 동절기 터널라이닝 및 배면의 동결피해를 줄일 수 있음을 확인하였다.

• 한국지반공학회논문집
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• 제35권1호
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• pp.17-30
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• 2019

본 연구는 3차원 수치해석을 통해 기존말뚝과 보강말뚝의 하중분담율(Load Distribution Ratio)과 근사적 해석 기법으로 보강말뚝의 축방향 강성(Axial Stiffness)을 산정하였다. 시공단계를 고려하여 말뚝기초의 LDR에 영향을 미치는 인자를 파악하기 위해서 1) 말뚝기초의 강성, 2) 말뚝기초의 선단지지조건, 3) 기초판 접촉효과, 4) 보강말뚝의 설치위치에 따라 해석을 수행하여 기존말뚝과 신설말뚝의 하중분담율 거동을 확인하였다. 또한 5) 기존말뚝의 축방향 강성($K_{ve}$)를 사용하여 말뚝지지 전면기초의 3차원 근사적 해석기법(YSPR)으로 보강말뚝의 직경에 따른 강성($K_{vr}$)을 산정하고, 장기간 사용으로 인한 경화를 고려하여 $K_{ve}$를 3단계로 나누어 감소시켜 보강말뚝의 강성 변화의 경향을 살펴보고, 신설 말뚝의 강성 산정방법을 제시하였다.

• 실내환경 및 냄새 학회지
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• 제16권2호
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• pp.187-198
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• 2017

It is very important to treat infected livestock carcasses safely and quickly. In this study, the degradation characteristics and odor generation characteristics of carcasses were investigated during the treatment of swine carcasses using the anaerobic burial composting method. While the carcasses were decomposed, the temperature remained high, at $40{\sim}55^{\circ}C$ on average, and most of the carcasses were decomposed rapidly. The major odor-contributing substances in the buried composting method are sulfuric odor substances such as $H_2S$, $CH_3SH$, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), and the odor contribution of these substances is 93~99%. Among them, $CH_3SH$, which accounts for about 56~89% of odor contribution, was the most representative indicator substance. Despite the anaerobic digestion process, the methane concentration in the digestion process was as low as 0.5~0.8% at the burial point of the carcass. The odor and methane produced during the decomposition of the carcasses decreased considerably during the discharge to the surface layer through the buried layer consisting of compost. These results suggest that anaerobic high temperature burial composting is one of the most useful methods to treat carcasses of infected livestock.

• 한국미생물·생명공학회지
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• 제49권3호
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• pp.432-439
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• 2021

Microbial community plays important roles in the culture environment of mud crab Scylla serrata. One of the environmental management efforts for the cultivation of S.serrata is by stabilizing microorganisms involved in nitrogen cycle process. The availability of dissolved inorganic nitrogen in its culture environment under a recirculating system closely relates to the nitrogen cycle, which involves both anaerobic and aerobic bacterial activities. Anaerobically, there are two major nitrogen compound degradation processes, i.e., denitrification and dissimilatory nitrate reduction to ammonium (DNRA). This study aimed to identify denitrifying and DNRA bacteria isolated from the recirculating cultivation of S. serrata. The water samples were collected from anaerobic filters called close filter system, which is anaerobically conditioned with the addition of varying physical filter materials in the recirculating mud crab cultures. The results showed that three denitrifying bacterial isolates and seven DNRA bacterial isolates were successfully identified. The phylogenetic analysis based on 16S rRNA gene of the denitrifying bacteria revealed that HIB_7a had the closest similarity to Stenotrophomonas daejeonensis strain MJ03. Meanwhile, DNRA bacterial isolate of HIB_92 showed a 100% similarity to Bacillus sonorensis strain N3, Bacillus vallismortis strain VITS-17, Bacillus tequlensis strain TY5, Geobacillus sp. strain DB24, Bacillus subtilis strain A1, and Bacillus mojavensis strain SSRAI21. This study provides basic information denitrifying and DNRA bacterial isolates identity which might have the potential to be applied as probiotics in aquaculture systems in order to maintain optimal environmental conditions.

• 한국지반환경공학회 논문집
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• 제12권11호
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• pp.31-37
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• 2011

본 연구는 Hydroxyapatite(HAP)/$TiO_{2}$ 여재에 의한 Reactive Black 5(RB5)의 흡착과 광촉매 반응을 조사하였다. RB5에 대한 $TiO_{2}$, HAP와 $TiO_{2}$/HAP의 흡착은 연속적인 회분식 실험을 통해 조사하였다. 흡착평형에 따른 결과를 나타내었으며 Langmuir와 Freundlich isotherm model을 사용하여 적용성을 조사하였다. $TiO_{2}$, HAP와 $TiO_{2}$/HAP 흡착제별 흡착평형 결과는 Langmuir isotherm model에 적합하였으며 최대흡착량(Qmax)의 값은 각각 단일 $TiO_{2}$는 5.28mg/g, 단일 HAP는 12.45mg/g, $TiO_{2}$/HAP는 9.03mg/g으로 나타났다. 흡착과 광촉매 반응에 대한 kinetic model들은 유사 1차 반응을 통해 분석하였으며, 이들 model에 따르면 $TiO_{2}$/HAP에 의한 RB5 제거는 광촉매 반응과 흡착반응의 상호작용의 영향을 받는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제85권2호
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• pp.275-287
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• 2023

The use of environmental-friendly building materials is becoming increasingly popular worldwide. Compared to the normal concrete, rubber-based concrete is considered more durable, environmentally friendly, socially and economically viable. In this investigation, M20 grade concrete was designed and the fine aggregates were replaced with crumb rubber of two different micron sizes (0.221 mm and 0.350 mm). Fly ash (FA) and silica fume (SF) replaces the binder as supplementary cementitious materials at a rate of 0, 5, 10, 15, and 20% by weight. The mechanical properties of concrete including compressive strength, tensile, and flexural strength were determined. The polynomial work expectation validates the response surface approach (RSM) concept for optimizing SF and FA substitution. The maximum compressive strength (22.53 MPa) can be observed for the concrete containing 10% crumb rubber, 15% fly ash and 15% silica fume. The reduced unit weight of the rubberized concrete may be attributed to the lower specific gravity of the rubber particles. Two-way ANOVA with a significance criterion of less than 0.001 has been utilized with modest residual error from the lack of fit and the pure error. The predictive model accurately forecasts the variable-response relationship. Since, the crumb rubber is obtained from wasted tires incorporating FA and SF as a cementitious ingredient, it helps to significantly improve mechanical properties of concrete and reduce environmental degradation.

• 한국물환경학회지
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• 제38권5호
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• pp.211-219
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• 2022

In this study, the effect of liquid height/volume on sonochemical oxidation reactions was investigated in 300 kHz sonoreactors. The gas mixture of Ar/O₂ (50:50) was applied in two modes including saturation and sparging, and zero-order reaction (KI dosimetry) and first-order reaction (Bisphenol A (BPA) degradation) were used to quantitatively analyze sonochemical oxidation reactions. For the zero-order reaction, the highest sonochemical oxidation activity was obtained for the liquid height of 5𝛌, and the lowest height for both the gas saturation and sparging conditions. In addition, the sparging did not enhance the sonochemical oxidation activity for all height conditions except for 50𝛌, where very low activity was obtained. It was found that in sonochemiluminescence (SCL) images the sonochemical active zone was formed adjacent to the liquid surface for the gas sparging condition due to the formation of the standing wave field while the active zone was formed adjacent to the transducer at the bottom due to the blockage of ultrasound. For the first-order reaction, the highest activity was also obtained at 5𝛌 and the comparison based on the reactant mass was not appropriate because the concentration of the reactant (BPA) decreased significantly as the reaction time elapsed. Consequently, it was revealed that the determination of optimal liquid height (ultrasound irradiation distance) based on the wavelength of the applied ultrasound frequency was very important for the optimal design of sonoreactors in terms of reaction efficiency and reactor size.

• 대기
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• 제33권5호
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• pp.531-548
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• 2023

We developed the Aviation Convective Index (ACI) for predicting deep convective area using the operational global Numerical Weather Prediction model of the Korea Meteorological Administration. Seasonally optimized ACI (ACI_SnOpt) was developed to consider seasonal variabilities on deep convections in Korea. Yearly optimized ACI (ACI_YrOpt) in Part 1 showed that seasonally averaged values of Area Under the ROC Curve (AUC) and True Skill Statistics (TSS) were decreased by 0.420% and 5.797%, respectively, due to the significant degradation in winter season. In Part 2, we developed new membership function (MF) and weight combination of input variables in the ACI algorithm, which were optimized in each season. Finally, the seasonally optimized ACI (ACI_SnOpt) showed better performance skills with the significant improvements in AUC and TSS by 0.983% and 25.641% respectively, compared with those from the ACI_YrOpt. To confirm the improvements in new algorithm, we also conducted two case studies in winter and spring with observed Convectively-Induced Turbulence (CIT) events from the aircraft data. In these cases, the ACI_SnOpt predicted a better spatial distribution and intensity of deep convection. Enhancements in the forecast fields from the ACI_YrOpt to ACI_SnOpt in the selected cases explained well the changes in overall performance skills of the probability of detection for both "yes" and "no" occurrences of deep convection during 1-yr period of the data. These results imply that the ACI forecast should be optimized seasonally to take into account the variabilities in the background conditions for deep convections in Korea.

• 농촌계획
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• 제30권1호
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• pp.43-55
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• 2024

The purpose of this study is to examine residents' perspectives on factors contributing to rural decline, including population decrease and landscape degradation, with the goal of proposing strategies to revitalize rural spaces in response to these challenges. After exploring rural decline issues in Jinan, a questionnaire was developed based on a review of existing research. Following this, participants were selected, and Focus Group Interviews(FGI) were conducted. Through the analysis of the findings, strategies for local revitalization were suggested in four sectors. Based on the research findings, there is a need to reassess public transportation and vacant property projects. On the social front, preventing the misuse of rural relocation policies and enhancing residential environments through spatial clarity are essential. Environmentally, clustering renewable energy and livestock facilities and attracting educational facilities are necessary to minimize disruption to rural landscapes. From a governance perspective, fostering entrepreneurship in rural tourism and business models utilizing the local landscape is crucial for an increase in regional visits. This study holds significance by emphasizing the practical situation of rural decline, steering away from resource-centric or business-focused policies. It underscores the potential usefulness of integrating this understanding into detailed planning within policies aimed at tackling rural decline.

• 보존과학연구
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• 통권25호
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• pp.31-45
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• 2004

The archeological remains usually exist in some excavated ancient soils. The ancients oils are buried in underground with the environmental, biological and social facts for circumstantial evidence at past times. Consequently, it is very important thing to carry out scientific analysis of the ancient soils side by side with archeological study. In this study, we accumulated some basic data for scientific analysis of 5 kinds of ancient soils excavated at Wanggung-ri, Iksan city. So we obtained some characterizations of organic chemical source, ancient parasite egg, and some seeds in the soils. The organic sources showed the content of high organic material as 7~22%, and strong acidic condition as pH 2~6. It is indicated that Wanggung-ri soils have included so many organic materials from the degradation of biological remains. Most of all, we searched a lot of eggs of parasite Trichuris trichiura and so it is possible that this area had been a ancient toilet at that times. The more scientific analysis of the soils will be showed us about the utility of the area, ancient dietary life style, ancient environment and ancient human diseases.