• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.478-478
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• 2021

전 세계적으로 많은 나라들이 기후변화에 적응하기 위해 수자원 관리 전략을 마련하고 있으며, 수자원의 근간이 되는 빗물의 효율적 사용을 위해 우리나라에서도 빗물이용시설이 많이 도입되고 있다. 본 연구에서는 사용자 편의 환경(graphical user interface; GUI)을 갖춘 빗물이용시설의 용량 결정 프로그램(capacity design aid for rainwater harvesting; CARAH)을 개발하여 관련 연구와 업무에 활용성을 높이고자 하였다. CARAH는 저수지 질량 보존식과 python의 pyswarm package에 탑재된 메타 휴리스틱 방법 중 하나인 입자 군집 최적화(particle swarm optimization; PSO) 기법을 연계하여 빗물이용시설의 최적 용량을 짧은 시간에 결정될 수 있도록 개발되었다. 그리고, C#의 Windows Forms Application을 이용하여 사용자 편의 환경을 구현하였다. CARAH의 입력 자료는 모의 기간, 유입량, 목표공급량, 공급보장률이고, 출력 자료는 공급보장률-저류조용량, 목표공급량-실공급량-미달성량, 저류용량-유입량-실공급량이다. 빗물이용시설 계획에 필요한 여러 입력 자료를 쉽게 입력할 수 있도록 구현하였고, 그래프와 표의 형태로 계산된 결과를 화면에 직접 표출함으로써 사용자가 직관적으로 확인할 수 있도록 하였다. 한편, 입·출력 자료를 포함한 분석 결과는 파일로 관리할 수 있도록 기능을 갖추어 수정 및 보완 등의 반복적 활용이 가능하도록 하였다. 개발된 프로그램의 활용성을 검토하기 위해 실제 저류지가 설계된 인천의 청라지구 1공구를 대상으로 적용하였고, 분석 결과의 적절성을 확인하였다. 본 연구에서 개발된 CARAH는 빗물이용시설의 용량 결정에 관한 효율을 높일 수 있는 프로그램이고, 누구나 쉽고 간편하게 사용할 수 있는 프로그램으로서 향후 활용성이 높을 것으로 판단된다.

• Journal of the Korean Applied Science and Technology
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• v.33 no.2
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• pp.352-360
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• 2016

The purpose of this study was to determine the electrochemical properties develop DSA electrode for sewage sludge solubilization. Using Ir as a main catalyst, the catalyst selected for the sewage sludge solubilization durability and proceeds to functional electrode suitable for sewage sludge electrolysis experiment were obtained the following results. Less mass reduction of the sintering temperature of the main catalyst, Ir coated electrodes, the endothermic reaction zone $300^{\circ}C$ to $500^{\circ}C$, which was selected from a range of experiments. The efficiency of the catalyst results came up to $350^{\circ}C$ best. Each Binder stars (Ta, Sn, W) in this experiment was the biggest catalyst efficiency at $350^{\circ}C$. Used as a binder, $TaCl_5$, $SnCl_4$, $WCl_6$ of the Ta and without affecting the other characteristics of the main catalyst than Sn, W. For the 50% $IrO_2$ electrode is 1.4 V (vs. Ag / AgCl) in a current of about $29mA/cm^2$ was caused to evaluate the effectiveness of the electrode.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1146-1153
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• 2008

Numerical simulation was carried out to study the trichloroethylene (TCE) degradation by permeable reactive barrier (PRB), and revealed the effect of concentration of TCE, iron medium mass, and concentration of iron-reducing bacteria (IRB). Newly developed model was based on axial dispersion reactor model with chemical and biological reaction terms and was implemented using MATLAB ver R2006A for the numerical solutions of dispersion, convection, and reactions over column length and elapsed time. The reaction terms include reactions of TCE degradation by zero-valent iron (ZVI, Fe$^0$) and ferrous iron (Fe$^{2+}$). TCE concentration in the column inlet was maintained as 10 mg/L. Equation for Fe$^0$ degradation includes only TCE reaction term, while one for Fe$^{2+}$ has chemical and biological reaction terms with TCE and IRB, respectively. Two coupled equations eventually modeled the change of TCE concentration in a column. At Fe$^0$ column, TCE degradation rate was found to be more than 99% from 60 hours to 235 hours, and declined to less than 1% in 1,365 hours. At the Fe$^{2+}$ and IRB mixed column, TCE degradation rate was equilibrated at 85.3% after 210 hours and kept it constant. These results imply that the ferrous iron produced by IRB has lowered the TCE degradation efficiency than ZVI but it can have higher longevity.http://kci.go.kr/kciportal/ci/contents/ciConnReprerSearchPopup.kci#

• KSBB Journal
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• v.16 no.4
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• pp.389-397
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• 2001

The effect of sludge digestion on the leaching efficiency of heavy metals from sludge by bioleaching with Thiobacillus thiooxidans MET was investigated. The used sludges were a non- and anaerobically digested. The leaching efficiency of heavy metals was strongly dependent on the pH of the sludge solution rather than the sludge condition and stolid concentration. The lower the pH the more heavy metal was leached from 3.0 of pH. The sequent orders of leaching heavy metals were Zn, Cu, and Cr. Although the buffering capacity of non-digested sludge was similar to anaerobically digested sludge, the pH decrease rate of the anaerobically digested sludge solution was faster than that of the non-digested sludge solution due to the higher sulfur oxidation rate of T. thiooxidans MET in the anaerobically digested sludge. The amount of leached heavy metals from the anaerobically digested sludge showed higher than that of non-digested sludge at the same pH value. This result might be caused by the difference of the insoluble metal types, which were contained in the sludge. An increase in sludge solids concentration decreased the leaching efficiency of heavy metals in the range of solids concentration 10 g/L to 70 g/L. The optimum ratio of S° to sludge stolid was 0.1 in both the sludge. The bioleaching process of heavy metals with T. thiooxidans MET showed the disinfecting effect over 90% as well as the reduction effect in sludge weight of 20%.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.97-104
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• 2020

The present study conducted mock-up tests under the simulated sewage environments to examine the practical significance and limitation of coating materials that were previously developed on the basis of the bacterial glycocalix as a protection of concrete structures exposed to microbiological and sulphate attacks. The variations of the compressive strength and mass of the concrete due to the sulphate attack were measured using cylinder specimens. The bacteria growth and glycocalix formulation were calculated from the samples extracted from the sewage pipes. The next generation sequencing analysis was also conducted for environmental damage assessment due to the use of Rhodobacter capsulatus in the simulated sewage environments. The mock-up tests revealed that the developed coating materials have a good potential in resisting the sulphate attack, indicating no reduction on compressive strength and mass of the coated concrete under the sewage environment. At the age of 91 days, the concentrations of viable bacteria and glycocalix measured from the hardened coating materials were 1.4×10⁴cell/mL and 67.5mg/㎤, respectively. Moreover, harmful strains were not observed in the sewage water including glycocalix-coated concrete pipes. This implies that Rhodobacter capsulatus used in the coating materials does not influence negatively the microorganism cluster in the sewage environments.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.3
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• pp.235-242
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• 2015

A commercially available copper mesh was investigated as an iodine off-gas capturing medium for pyroprocessing, with an aim to replace costly silver based adsorbents. Theoretical calculation results suggested that the reaction between metallic copper and gaseous iodine will occur spontaneously to produce copper iodide in the temperature range of 100 ~ 500℃. The effect of the reaction temperature on iodine capturing efficiency was investigated by experimentation, and it was found that 5 and 6 wt% of iodine (initial mass 2.0 g) was captured by a single copper mesh (0.26 g) at 300 and 400℃, respectively. The repeated experimental results also suggested that copper utilization can be increased with the help of the spontaneous detachment of the reaction product (CuI) from a copper mesh. The formation of the CuI phase was confirmed using the X-ray diffraction technique, and the surface morphology of the reaction product was observed using scanning electron microscopy.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.117-122
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• 2008

Although the pulse diagnosis is the one of the most important diagnostic process to traditional medical doctors, there is no proper communication tool between experts and trainees. In this paper, we have developed a indentation training system which consists of a hardware measuring indent pressure on artificial arm quantitatively and a software providing a indentation training program. The hardware for measurement of indent pressure profile includes 3 load cells embedded in the artificial arm, signal amplification part and digitization part, NI-USB 6009 with 200Hz sampling rate. For setting up a relationship table between weights and output voltages, 8 standard weights were used. To evaluate this hardware, 3 oriental medical specialists were involved and their indent pressure profile were recorded three times respectively. From these, it was found that pulse diagnosis process could be divided into 3 periods and the maximum load were $500g{\cdot}f$ approximately while doctors perform a pulse diagnosis. The indentation training program was implemented with LabView and designed to monitor the differences between the pressure profile of a expert and that of a trainee so to offer some visual feedback to the trainee. Also, this program could provide the trends of training performances. With this developed system, the education of pulse diagnosis is expected to be more quantitative and effective.

• Analytical Science and Technology
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• v.16 no.2
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• pp.152-158
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• 2003

This study was conducted to evaluate two sample digestion procedures and instrumental determination parameters for analysis of lead in bone. Amputated human legs were treated by acid digestion or microwave dissolution prior to spectrometric analysis. Inductively coupled plasma mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GF-AAS) were used for determining bone lead levels. Recovery efficiencies using standard reference material from acid digestion measured by ICP-MS were in good agreement with those of the certified value, but in cases of acid digestion by GF-AAS and microwave digestion by both two methods, recovery underestimated and overestimated, respectively. For the bone samples, the lead concentrations obtained by ICP-MS after acid digestionwere in good agreement with those by GF-AAS (correlation coefficient = 0.983), but GF-AAS gave systematically higher values than ICP-MS. While a good agreement between two analytical methods after microwave digestion was also obtained (correlation coefficient = 0.950), bone lead concentrations from microwave were relatively higher than those from acid digestion. In conclusion, the use of the simple nitric acid digestion procedure at an ambient temperature coupled to ICP-MS seems to be efficient for the determination of lead in bone in consideration for both the convenience and validity.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.3-11
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• 1999

The effects of major cations in soils, soil : extractant ratio, and EDTA : lead stoichiometric ratio on the extraction efficiency of lead using EDTA were studied for 4 different actual lead-contaminated soils and one artificially lead-contaminated soil. Extraction of lead from the lead-contaminated soil was not affected by a soil : extractant ratio as low as 1 : 3 but instead was dependent on the quantity of EDTA present. Results of the experiments showed that the extraction efficiency for each soil was different, but if sufficiently large amount of EDTA was applied, all the lead may be extracted except for a soil from lead mining area. The differences in extraction efficiencies nay be due to the major cations present in soils which may compete with lead for active sites on EDTA. The total molar amount of major cations extracted was as muck as 20 times more than the added molar amount of EDTA. For some of the soils tested, the extraction efficiency of lead may be affected by being occluded in the Fe and Mn oxides present in the soil. While major cations present in the soil may be one of the factors affecting lead extraction efficiency, the type of lead species present may also play a role. When these factors affect severely, the using of EDTA to extract lead from lead-contaminated soil might be non-effective method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.389-397
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• 2014

An absorption chiller-heater using only a natural refrigerant hardly causes any environmental pollution. In an absorption chiller-heater, the performance of its high-temperature generator, which uses exhaust gases, is essential to achieving superior system performance. To investigate the performance of such a high-temperature generator, a laboratory-scale high-temperature generator working with exhaust gases was designed and tested. Changes in the performance of the high-temperature generator as a function of inlet conditions of the absorbing solution, such as air inlet temperature and mass flow, were investigated. It was observed that when the air mass flow rate ratio was increased from 80% to 120%, the heat capacity was increased by 30%, 33%, 34%, and 37%, respectively. Additionally, when the air inlet temperature was elevated from $170^{\circ}C$ to $210^{\circ}C$ for absorption solution concentrations of 56%, 55%, 545, and 53%, the heat capacity increased by 140%, 160%, 220%, and 224%, respectively.