• 한국물환경학회지
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• 제36권6호
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• pp.535-545
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• 2020

This study aims to conserve and monitor energy use in public sewage treatment plants by utilizing data from the SCADA system and by controlling the aeration rate required for maintaining effluent water quality. Power consumption in the sewage treatment process was predicted using the equipment's uptime, efficiency, and inherent power consumption. The predicted energy consumption was calibrated by measured data. Additionally, energy efficiency indicators were proposed based on statistical data for energy use, capacity, and effluent quality. In one case study, a sewage treatment plant operated via the SBR process used ~30% of energy consumed in maintaining the bioreactors and treated water tanks (included decanting pump and cleaning systems). Energy consumption analysis with the K-ECO Tool-kit was conducted for unit processing. The results showed that about 58.7% of total energy consumed was used in the preliminary and biological treatment rotating equipment such as the blower and pump. In addition, the energy consumption rate was higher to the order of 19.2% in the phosphorus removal process, 16.0% during sludge treatment, and 6.1% during disinfection and discharge. In terms of equipment energy usage, feeding and decanting pumps accounted for 40% of total energy consumed following 27% for blowers. By controlling the aeration rate based on the proposed feedback control system, the DO concentration was reduced by 56% compared pre-controls and the aeration amount decreased by 28%. The overall power consumption of the plant was reduced by 6% via aeration control.

• 에너지공학
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• 제8권4호
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• pp.605-611
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• 1999

화력발전설비 고온요소의 잔여수명평가는 주로 비파괴검사 및 검사결과의 파괴역학적 해석등으로 행해졌다. 그러나 기존 방법은가동중에는 적용되기 어렵고 급작스런 운전이력에 대한 정량적인 손상을 평가할 수 없었다. 따라서 구조물의 형상, 운전이력 및 재료물성에 근거하여 실시간 수명소비율 및 잔여수명을 평가하는 기술의 개발이 요구되고 있다. 본 연구에서는 고온 증기헤더의 수명을 실시간으로 평가하는 감시시스템 소프트웨어를 개발하였다. 고온헤더에 대하여 해석된 온도, 응력, 그린함수를 이용하여 취약부위의 실시간 응력을 계산하고 천이 사이클을 카운트하여 크리프 및, 피로수명을 계산하였다. 본 소프트웨어를 개발함으로써 운전이력에 따른 소비수명을 실시간으로 평가하고 운전정보를 기록하여 향후 운전계획, 보수주기 및 교체시기를 결정하는데 지침이 되도록 하였다.

• 한국조경학회지
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• 제47권1호
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• pp.88-103
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• 2019

옥구공원 내 공간기능에 적절한 식재개념을 설정하고, 생육환경에 적합한 식재디자인을 제시하고자 하였다. 공간기능은 공원 시설물과 주변 현황, 이용 현황을 파악하여 구분하였고, 식재개념은 식재종 분포 및 정밀 식재구조를 조사하여 파악하였다. 식재종 분포는 48개의 유형으로 잔디식재지(28.84%), 왕벚나무(8.0%), 곰솔(6.73%), 느티나무(6.38%) 순이었다. 정밀 식재구조 조사구는 27개소를 설정하였으며, 조사 및 분석 결과, 평균 녹피율은 38.14%, 평균 녹지용적계수는 $0.72m^3/m^2$이었다. 생육불량률은 개체 수목별 생육상태를 등급화하여 녹지 블록당 평균값으로 도출하였다. 식재디자인 대상지는 옥구공원 중 공간의 활용도가 낮고, 수목의 생육환경이 열악한 지역을 선정하였다. 공간기능과 식재개념의 비교 분석 결과와 수목의 생육을 평가하여 생육 불량한 지역 $36,236m^2$를 파악하였다. 그리고 공간구조와 주요 이용 주변지역을 분석하여 식재개선이 시급한 지역을 도출하였다. 식재디자인 사례지역은 분수 주변지역의 녹음공간을 대상으로 현존식생과 층위구조, 이용 현황 등을 고려하여 식재디자인을 구상하였다. 선정된 지역은 식재디자인을 통하여 경관향상을 위한 식재개념 및 방향을 설정하고, 각 공간별 식재설계를 제안하였다.

• 한국자원식물학회지
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• 제24권4호
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• pp.379-394
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• 2011

본 연구는 강원도 남부지역에서 이용되는 민속식물을 파악하기 위하여 2010년 3월부터 10월까지 수행되었다. 9개시 군지역의 32개소에서 주민 83명을 대상으로 수집한 조사야장 1,103장의 설문조사를 분석한 결과, 강원도 남부지역에서 파악되고 수집된 민속식물은 총 92과 222속 274종 2아종 29변종 6품종의 총 311분류군으로 정리되었다. 용도별 이용은 식용 227종류, 약용 174종류, 관상용 14종류, 유지 5종류, 향신료 5종류, 염료 4종류, 섬유 1종류, 향료 1종류, 연료 1종류, 기타 32종류로서 식용으로의 이용 빈도가 가장 높았으며, 이용 부위로는 잎, 뿌리, 열매, 줄기 순으로 나타났다. 연령별 표준식물명과 지방명의 일치성은 50대에서 가장 높았으며, 80대에서 가장 낮았다.

• 한국식품과학회지
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• 제37권6호
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• pp.1042-1047
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• 2005

작업 현장에서 사용하는 살균소독제의 유효성을 평가하고 사용되는 제품의 저장기간별 안정성을 조사하였다. 다양한 식품을 생산하는 공장에서 식품가공 시 살균소독제 사용전후 미생물 오염정도를 파악하고 네 가지 대표 살균소독제의 보관기간 별 살균력의 안정성을 조사하기 위하여 2개월 간 저장성 시험을 실시하였다. 8개 식품가공공장에서 실제 사용 중인 살균소독제를 테스트한 결과, 살균소독제 사용 전 일반세균수는 $10^1-10^5CFU/cm^2$, 대장균군수는 $10^1-10^2CFU/cm^2$, 대장균은 $10CFU/cm^2$ 미만이었으며 살균소독제 사용 후 일반세균수는 $10^1-10^3$ 수준으로 감소하였으나 모두 사멸시키지는 못하였다. 살균소독력 지속여부를 S. aureus 와 E. coli를 이용하여 검증한 결과, 권장사용농도에서 alcohol계, hydrogen peroxide계, QAC계 제품은 2개월간 그 효과가 유지되었으나 chlorine계 제품은 개봉 2주 이내에 8 log에서 4 log로 효과가 감소되는 것으로 나타났다. 실제 법적으로 인정을 받은 살균소득제는 in vitro에서 S. aureus와 E. coli를 5 log 감소시켜 그 살균력을 인정받았으나 실제 현장에서는 그 정도의 효과를 거두지 못하고 있으며 개봉 후 즉시 사용하지 않고 보관될 경우 그 효력이 현저히 감소되는 것으로 파악되었다.

• Restorative Dentistry and Endodontics
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• 제40권1호
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• pp.50-57
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• 2015

Objectives: The usage of medicinal plants as natural antimicrobial agents has grown in many fields including dental medicine. The aim of this in vitro study was three-fold: (i) to determine the chemical compositions of the Ferula gummosa essential oil (FGEO), (ii) to compare the antimicrobial efficacy of the oil with sodium hypochlorite (NaOCl) and chlorhexidine (CHX), (iii) to assess the toxic behavior of FGEO in different concentrations compared to 5% NaOCl and 0.2% CHX. Materials and Methods: Gas chromatography/mass spectrometry (GC/MS) was used to determine the chemical compositions of the oil. The disk diffusion method and a broth micro-dilution susceptibility assay were exploited to assess the antimicrobial efficacy against Enterococcus faecalis, Staphylococcus aureus, Streptococcus mitis, and Candida albicans. The cytocompatibility of the FGEO was assessed on L929 fibroblasts, and compared to that of NaOCl and CHX. Results: Twenty-seven constituents were recognized in FGEO. The major component of the oil was ${\beta}$-pinene (51.83%). All three irrigants significantly inhibited the growth of all examined microorganisms compared to the negative control group. FGEO at $50{\mu}g/mL$ was effective in lower concentration against Enterococcus faecalis than 5% NaOCl and 0.2% CHX, and was also more potent than 0.2% CHX against Candida albicans and Staphylococcus aureus. FGEO was a cytocompatible solution, and had significantly lower toxicity compared to 5% NaOCl and 0.2% CHX. Conclusions: FGEO showed a promising biological potency as a root canal disinfectant. More investigations are required on the effectiveness of this oil on intracanal bacterial biofilms.

• 전기학회논문지
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• 제59권8호
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• pp.1456-1463
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• 2010

The safety critical systems in nuclear power plants should be designed to have a high level of fault tolerant capability because those systems are used for protection or mitigation of the postulated accidents of nuclear reactor. Due to increasing of the system complexity of the digital based system in nuclear fields, the reliability of the digital based systems without an auto-test or a self-diagnostic feature is generally lower than those of analog system. To overcome this problem, additional redundant architectures in each redundant channel and self-diagnostic features are commonly integrated into the digital safety systems. The self diagnostic function is a key factor for increasing fault tolerant capabilities in the digital based safety system. This paper presents an availability and safety evaluation model to analyze the effect to the system's fault tolerant capabilities depending on self-diagnostic features when the loss or erroneous behaviors of self-diagnostic function are expected to occur. The analysis result of the proposed model on the several modules of a safety platform shows that the improvement effect on unavailability of each module has generally become smaller than the result of usage of conventional models and the unavailability itself has changed significantly depending on the characteristics of failures or errors of self-diagnostic function.

• Corrosion Science and Technology
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• 제4권4호
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• pp.155-163
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• 2005

Heavy duty coating are required to have minimum durable period of 15 years under average usage environment because these paints are coated with purpose of anti-corrosion, antifouling, plastering etc. Onto steel structures constructed upon land and sea and other ferrous structures of electric power generation plants, electricity transmission towers, large structures of various plants, etc. Therefore we tried to estimate heavy duty coating longevity through reliability evaluation method and used combined cyclic anti-conrrosion test method composed of drying, moisturizing and salt spray as for accelerated life test to estimate longevity. Accelerated life test hours to heavy duty coating of first grade (with longevity not less than 15 years) specification may be obtained from troubleless test hours $t_n=\frac{B_p}{n^{1/\beta}}\left[\frac{1n(1-CL)}{1n(1-p)} \right]^{1/\beta}=19.671$ (yr) where shape parameter $\beta=1.1$, confidence level CL=80 %, warranty life $B_{10}=15$ yr and sampling size n=10 (2 sets). Because acceleration factor {AF} found by accelerated test is 41.7, accelerated life test hours required may be represented about 4,132 hr so that if this amount of hours is converted to number of cycles(6 hr/cycle) of complex cycle corrosion resistance test then the amount is tantamount about 690 cycles. That means if there does not occur trouble failure (with defect factor sum not more than 20) during when there is performed 690 cycles of combined cyclic anti-corrosion test to heavy duty coating specimen then it signifies that there can be warranted longevity $B_{10}$ of 15 yr under condition of confidence level CL=80 %.

• Advances in environmental research
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• 제3권2호
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• pp.173-183
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• 2014

A comprehensive mathematical model was developed for this study to estimate on-site and off-site GHG emissions from wastewater treatment plants (WWTPs). The model was applied to three different hybrid WWTPs (S-WWTP, J-WWTP, and T-WWTP) including anaerobic, anoxic, and aerobic process, located in Seoul City, South Korea. Overall on-site and off-site GHG emissions from S-WWTP, J-WWTP, and T-WWTP were $305,253kgCO_2e/d$, $282,682kgCO_2e/d$, and $117,942kgCO_2e/d$, respectively. WWTP treating higher amounts of wastewater produced more on-site and off-site GHG emissions. On average, the percentage contribution of on-site and off-site emissions was 3.03% and 96.97%. The highest amount of on-site GHG emissions was generated from anoxic process and the primary on-site GHG was nitrous oxide ($N_2O$). Off-site GHG emissions related to electricity consumption for unit operation was much higher than that related to production of chemicals for on-site usage. Recovery and reuse of biogas significantly reduced the total GHG emissions from WWTPs. The results obtained from this study can provide basic knowledge to understand the source and amount of GHG emissions from WWTPs and strategies to establish lower GHG emitting WWTPs.

• 인간식물환경학회지
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• 제22권6호
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• pp.665-676
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• 2019

The Korean society is currently showing a decrease in the child population and a rapid increase in the elderly population due to low birth rates and aging, but the current park system does not reflect the changing population structure. This study aimed to find ways to plan and promote use of senior-friendly parks for the aging society. The results are as follows. First, the elderly mostly gathered in Tapgol Park and Jongmyo Park which were accessible to subways and close to amenities and traditional markets. The elders usually gathered around buffer zones or green spaces set up to protect cultural heritages. Second, many elderly users were observed in Osolgil Silver Park and Sinteuri Park which were renovated with senior-friendly concept. These parks were recognized as places that the elderly people could visit without minding users of other generations because the elderly users were ensured by words such as 'seniors only' or 'senior-friendly'. Third, the importance of the locational conditions for the senior-friendly parks should be mentioned. A senior-friendly park must be located in an urban center to have convenient access to transportation, secure large green spaces, and make elderly users feel at ease with social connectivity when they use the amenities there. Fourth, the survey results showed that elderly people visited parks to exerciseand take a walk (track),by age, older age groups visited the park to socialize with other elders around their age. Fifth, the most desired facilities for constructing senior-friendly parks were fitness equipment, and sports facilities like a trail, track, and gateball field, and in some cases, vegetable gardens and indoor rest area to avoid wind in cold weather.