• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.1155-1158
• /
• 2006

This paper presents a study on the construction condition and environmental effect of deep soil mixing. Construction condition means the difference in unconfined compressive strength with respect to the depth and location of samples. Environmental effect means alkalinity diffused from soil stabilizer. The experimental results indicate that the unconfined compressive strength vary with respect to the depth, and doesn't show consistency pattern. So, in field application we must decide a mixing ratio enough to satisfy the least unconfined compressive strength. The difference in unconfined compressive strength with respect to the location of samples is negligible. The generation of alkalinity from soil stabilizer is reduced by permeating in non-improved soil and it is expected that the diffusion of alkalinity has no environmental effect on soil and ground water.

• Journal of Advanced Research in Ocean Engineering
• /
• 제4권2호
• /
• pp.53-65
• /
• 2018

The load condition significantly influences ship maneuverability in calm water. In this research, the effect of the load condition on turning performance of a very large crude oil carrier (VLCC) sailing in adverse weather conditions is investigated by an MMG-based maneuvering simulation method. The relative drift direction of the ship in turning to the wave direction is $20^{\circ}-30^{\circ}$ in ballast load condition (NB) and full load condition (DF) with a rudder angle $35^{\circ}$ and almost constant for any wind (wave) directions. The drifting displacement in turning under NB becomes larger than that under DF at the same environmental condition. Advance $A_d$ and tactical diameter $D_t$ become significantly small with an increasing Beaufort scale in head wind and waves when approaching, although $A_d$ and $D_t$ are almost constant in following wind and waves. In beam wind and waves, the tendency depends on the plus and minus of the rudder angle.

• 대한환경공학회지
• /
• 제31권10호
• /
• pp.855-864
• /
• 2009

본 연구에서는 질산화 반응이 활발히 진행되고 있는 기존 하수처리장 슬러지를 이용하여 3개월 이상 농축 배양한 후에 부착 및 부유성장 상태로 적응시킨 질화균을 이용하여 독성물질에 대한 영향을 조사하였다. 본 실험의 목적은 부유 및 부착성장 질화균을 이용하여 이들의 비표면적에 따른 독성물질의 영향을 상호비교하기 위한 것이다. 이를 위하여 부유 및 부착상태의 농축 질화균의 비표면적을 다르게 하여 각각에 대한 독성물질의 영향을 조사하였다. 연구 결과 부착성장 질화균 및 부유성장 질화균의 경우 비표면적이 클수록 독성에 대한 영향을 더 많이 받는 것으로 나타났다. 부착상태와 탈착상태의 질화균을 사용한 실험에서, 독성물질에 대한 영향은 탈착상태보다 부착상태에서 독성의 영향을 적게 받았으며, Nitrosomonas의 경우에는 1.12배, Nitrobacter의 경우에는 1.09배 독성의 영향을 적게 받았다. 부유성장 질화균을 사용한 경우에는 분쇄 전보다 분쇄 후에 독성의 영향을 더 크게 받았으며, Nitrosomonas의 경우에 1.46배, Nitrobacter의 경우에 1.35배 독성의 영향을 적게 받았다. 또한, 기질에 아질산염을 주입하지 않고 실험한 결과에서도 유사한 결과를 얻었다. 부착상태와 탈착상태의 질화균을 사용한 실험에서, 독성물질에 대한 영향은 탈착상태보다 부착상태에서 독성의 영향을 적게 받았으며, Nitrosomonas의 경우에는 1.83배, Nitrobacter의 경우에는 1.78배 독성의 영향을 적게 받았다. 부유성장 질화균을 사용한 경우에는 분쇄 전보다 분쇄 후에 독성의 영향을 더 크게 받았으며, Nitrosomonas의 경우에 1.27배, Nitrobacter의 경우에 1.32배 독성의 영향을 적게 받았다.

• 한국환경교육학회지:환경교육
• /
• 제14권1호
• /
• pp.19-31
• /
• 2001

This study examined the effect of environmental alteration and prompts on recycling behavior. An A-B-BC with a control condition design was employed. Subjects in this study were college students, professors, and employees at a university building. After a baseline phase, environmental alteration was I effect in the next phase and both environmental alteration and prompts were in effect in the final phase for the control condition. The environmental alteration consisted of providing four separation containers for the paper cups, cans recyclable paper, and the disposable on each floor in the building. The prompts consisted of providing the information about the importance of environmental preservation and how to separate the materials in the appropriate containers using an information board and pamphlets. The dependent variables were (1) the number of cans collected in can container, (2) the number of paper cups collected in cup container, (3) the rate of correct separation of cans, (4) the rate of correct separation of paper cups, and (5) the weight of disposable. The rates of correct separations of cans and paper cups were obtained by calculating the percentage of thenumber of recyclable cans and paper cups in the corresponding containers. The results indicated that environmental alteration had positive effects on all the dependent variables. Also, when the prompts were added to the environmental alteration, the incremental effect of the prompts was demonstrated. The implications and limitations of theses findings were discussed and the direction of future studies was also proposed.

• 한국환경과학회지
• /
• 제30권12호
• /
• pp.1093-1100
• /
• 2021

The present study investigated the effect of ammonia load on microbial communities in mesophilic anaerobic digestion of propionic acid. A laboratory-scale continuous anaerobic digester treating propionic acid as a sole organic substrate was operated under non-inhibitory condition and inhibitory conditions with ammonia (1.5 g and 3.5 g ammonia-N/L, respectively), and bacterial and archaeal communities in the steady states of each ammonia condition were analyzed using high-throughput sequencing. Thirteen bacterial families were detected as abundant bacterial groups in mesophilic anaerobic digestion of propionic acid. Increase in ammonia concentration resulted in significant shifts in microbial community structures. Syntorophobacter, Pelotomaculum, and Thermovigra were determined as the dominant groups of (potential) propionate oxidizing bacteria in the non-inhibitory condition, whereas Cryptanaerobacter and Aminobacterium were the dominant groups of (potential) propionate oxidizing bacteria in the ammonia-inhibitory condition. Methanoculleus and Methanosaeta were the dominant methanogens. Acetate-oxidation coupled with hydrogenotrophic methanogenesis might be enhanced with increases in the relative abundances of Methanoculleus and Tepidanaerobacter acetatoxydans under the ammonia-inhibitory condition. The results of the present study could be a valuable reference for microbial management of anaerobic digestion systems that are exposed to ammonia inhibition and propionic acid accumulation.

• 한국도로학회논문집
• /
• 제16권3호
• /
• pp.51-57
• /
• 2014

PURPOSES : This study is to suggest tunnel length to spray curing compound, based on the field tests. METHODS : At first field test, length from the entrance of tunnel to wet wall was checked by visual survey. The second and third test, various sensors were installed in concrete or in tunnel, such as RH sensor, temperature sensor, portable weather station and etc.. And also, test for bleeding and retaining water of concrete were conducted to evaluate environmental effect on concrete pavement. RESULTS : The result of the field experiment for tunnel length to spray curing compound indicates that length changes depending on tunnel length, season, and location. Environmental condition of a short tunnel was not much different between location near entrance and at center of tunnel. However, in case of a medium and long tunnel, effect of outside environmental condition decreased, when location moved into tunnel center of it. CONCLUSIONS : From the testing results, it can be proposed that optimum tunnel length to spray curing compound is 60m for a medium and long tunnel, and whole length for a short tunnel.

• 산업기술연구
• /
• 제39권1호
• /
• pp.21-25
• /
• 2019

This work experimentally determined the effect of microaerobic condition on anaerobic digestion of thickened waste activated sludge in semi-continuous mesophilic digesters at hydraulic retention time of 20 days. The concentration of hydrogen sulfide was $7{\pm}2ppm$ at the microaerobic condition and $14{\pm}2ppm$ at the anaerobic condition. Removal efficiency of volatile solid was not significantly different between microaerobic ($40{\pm}8%$) and anaerobic ($38{\pm}8%$) conditions. There was no important difference between microaerobic ($1,352{\pm}98ml/d$) and anaerobic ($1,362{\pm}104ml/d$) conditions in the biogas production, either. Therefore, it could be concluded that the application of the microaerobic condition was an efficient method of the hydrogen sulfide removal from the biogas.

• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2009년도 추계학술발표논문집
• /
• pp.100-102
• /
• 2009

Effect of temperature, pH and soil depth on germination of Dianthus chinensis, Dianthus barbatus, and Perennial pennant were investigated in growth chamber and soil condition at the ratio of 7:3 (natural soil and organic soil) in laboratory condition. the optimum temperature for seed germination was recorded for $20^{\circ}C-\;25^{\circ}C$. Maximum germination was observed for Dianthus barbatus (76%) where as in soil condition Perennial pennant (51%) showed maximum germination at 1 cm soil depth. Similarly, optimum pH for seed germination was at pH 6 in all the species. So in lower pH (at pH4) seed germination was inhibited. Germination of these selected species at different environmental condition help to construct the ecological sound proof wall to mitigate the noise especially in urban areas.

• 환경영향평가
• /
• 제21권1호
• /
• pp.81-91
• /
• 2012

In this study, it is grasped the status of nutrients through an investigation of release characteristics and physicochemical properties of sediments on reservoir. And then the effect of sediments is evaluated on the water quality in reservoir. In the results of physicochemical analysis, the pollution level of midstream is the highest, which shows the traits that the water is more deeper and takes place a deposition consistently. Then, the pollution level of upstream is higher than downstream's because inflow has influence on the upstream directly. The downstream is located near tidal gate so that the soil particles can be moved easily and are difficult to be deposited due to the distribution of seawater by control of tidal gate. Therefore, the downstream is showed the lowest pollution level than the others. Also, the concentration of SOD(Sediment Oxygen Demand) in the upstream which is influenced on the effect of inflow is highest than the others. When it analyzes under anaerobic and aerobic condition to understand the release characteristic of sediment, it shows that the release rate is low or negative under the aerobic condition. Whereas the release rate is usually positive under the unaerobic condition relatively. According to these results, it is necessary to maintain the proper environmental factors of water body for decreasing the release rate of sediment. Because the release rate is changeable under the different condition of water body. Therefore, proper strategies are required for increasing the self-purification of water as well as keeping the aerobic condition of sediment and managing a sediment layer directly to control the inner-pollution by the sediment of reservoir.

• Journal of Ship and Ocean Technology
• /
• 제9권1호
• /
• pp.11-26
• /
• 2005

In this study, the program to investigate the multiple body interaction effects between a floating platform and a shuttle tanker considering the coupled effect of hull (FPSO) with mooring lines and risers was developed. The coupled analysis program, which is called WINPOST-MULT using the hydrodynamic analysis results by WAMIT, was made. For the verification of WINPOST-MULT by means of numerical experiments, two multiple-body models of an FPSO-FPSO and an FPSO-shuttle tanker system are adopted. With the FPSO-FPSO model and a two-mass-spring system to idealize two identical bodies for the 100-year storm wave condition in GOM, the numerical simulations were performed to investigate the interaction effects between two identical bodies. For the more reality, the coupled analysis for the FPSO-shuttle tanker model in the tandem arrangement was carried out in the consideration of the environmental condition of the West Africa Sea as a rather mild condition. Through the case studies with interaction effect and without interaction effect by the iteration method and the combined method, it is verified that the program is a very useful tool for the analysis of the interaction problem of multiple-body system and the coupled problem of the hull/mooring/riser.