• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2203_2104
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• 2009

아크는 전원의 양단에 큰 전류가 흐를 때 공기의 이온화와 발열로 인하여 생성된 플리즈마로 정의될 수 있다. 최근 경제발전과 IT산업 발달로 큰 전력계통에서 안정적인 전력 공급이 중요하므로 이러한 아크가 발생하면 부하의 정전사태를 방지하기 위해 일시고장인지 영구 고장인지 빠르게 판단하여 재폐로를 수행하여야 한다. 이를 위해 아크에 대한 특성을 살펴보는 것은 반드시 필요한 사항이므로 본 논문에서는 아크가 발생하는 고장지점에 따른 아크의 특성 변화를 EMTP로 모델링 하여 살펴보고자 하였다. 일반적으로 아크는 특성상 매우 복잡한 구조를 가지며 여러 주위 조건들에 따라 그 특성이 변화한다. 아크의 발생 원인이 되는 사고는 크게 일시고장과 영구고장으로 나눌 수 있는데 여기서 모델링한 것은 스위칭 작용에 의한 2차아크가 발생하는 일시고장의 경우라고 가정하였다. 그리고 아크를 모델링함에 있어서 아크의 특성과 유사한 ZnO 아크 모델을 이용하여 송전선로의 한 상에 연결시켜 연구를 수행하였다.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.664-666
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• 2005

본 논문에서는 장거리 초고압 송전선로에서의 단상재폐로시에 발생가능한 과전압과 2차아크전류를 EMTP를 이용하여 예측계산 하였다. 예측계산결과로부터 과전압을 억제하고 재폐로 동작이 가능한 최적의 중성점 리액터와 400 kV 급 수평배열 1회선 선로를 단상으로 재폐로 하는데 필요한 재폐로 무전압시간을 구하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1032-1041
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• 2009

그라운드 앵커의 유지관리 점검 목적은 크게 두 가지로 구분된다. 첫째는 기 시공된 앵커 및 앵커 구조물이 설계 의도에 맞게 적절히 작용(기능)하고 있는지를 점검하고 원래 목적한 기능을 수행하도록 보수 보강하기 위함이며, 둘째는 점검결과를 바탕으로 장기적인 운용에 따라 앵커에 발생하는 결함을 보완하도록 유지관리를 고려한 설계에 활용하기 위함이다. 그러나 그라운드 앵커가 도입된 이후 40여년이 지났지만 아직 국내의 실정에 맞는 유지관리의 방안이 마련되어 있지 않은 것이 현실이며, 특히, 장기간 그 기능을 유지해야 하는 영구앵커의 경우는 유지관리가 더욱더 중요한 과제이다. 따라서, 본 연구에서는 그라운드 앵커의 유지관리 점검에 대한 방안을 제안하고자 한다.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.106-114
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• 2019

The effect of physical and chemical treatments to reduce staphylococcal phages was investigated. To determine impact of physical treatment on viability of phages, two staphylococcal phages (SAP84 and SAP89) were treated with multiple heat ($55^{\circ}C$ and $60^{\circ}C$) and pH (pH4, 7, 10) conditions. Viability of SAP 84 was dramatically reduced at 60C and SAP 89 was completely inactivated at 60C within 25 min. Overall, the two phages were stable under all the pH conditions tested except for the SAP 89 at pH 10. Treatments, a 10% FAS (Ferrous Ammonium Sulfate) solution and various density of ethanol and sodium hypochlorite were used to reduce the two phages. SAP 84 was unstable in 50% and 70% ethanol. However, SAP 84 and SAP 89 showed high tolerance after exposure to 100 ppm of sodium hypochlorite which is known as an effective sterilizer. As soon as the two phages were treated with 10% FAS, which is used as a virucidal agent, they were inactivated and did not form any plaque. The result of this study provides additional evidence that staphylococcal phages can be controlled by various physicochemical treatments.

• Resources Recycling
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• v.15 no.2 s.70
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• pp.45-49
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• 2006

The removal of copper ion from aqueous solution by adsorption with bone char that made from spent pig bone has been studied. This paper was studied the effects of bone char dosage and pH. The optimal results show that bone char adsorbs about 96.5 percent of copper ion in aqueous solution containing 50 mg/L as initial concentration at pH 5.0 when the bone char of 5g/L is used for 30 hours. Increase in the initial pH of the copper solution resulted in an increase in the copper ion uptake per weight of the sorbent Freundlich isotherm model was found to be applicable for the experimental data of $Cu^{2+}$.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.148-149
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• 2022

본 논문에서는 지역별로 발생 양상이 다른 사회재난의 종합적 위험분석을 위한 정보활용 방안 및 전략을 제안한다. 사회재난은 재난유형이 매우 다양하며, 각기 다른 발생 및 전파양상을 가지고 있어 전문성을 기반으로 관계하고 있는 개별부처에서 각각 관리되고 있다. 재난이 발생 후 대응, 수습 및 복구에 이르는 활동은 대표적인 현장대응 부처인 행정안전부, 경찰청, 소방청 등에서 주로 담당하고 있으나, 예방 및 대비 활동은 각 부처에서 개별법령에 의한 제도 및 정책에 의해 위험요소를 저감하기 위한 활동으로 진행된다. 예를 들어 화학사고의 경우 화학사고예방관리계획서, 장외영향평가, 화재는 방화지구, 화재경계지구, 산불은 산불취약지수 등 각각의 물리적 매커니즘을 적정히 고려하는 이론적 근거의 의해 사전에 그 위험을 평가하고 있으나 재난관리 예방을 담당하는 부처에 까지 연속성을 가지고 그 결과들이 적극적으로 활용되고 있지 못하고 있다. 이에 본 연구에서는 각 부처에서 개별법령에 의해 평가되는 공신력 있는 자료들의 융합적 해석에 근거한 종합위험 평가 개념을 정립하고 실제 활용 가능성에 대해 논하고자 한다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.10
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• pp.1225-1233
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• 2017

The aim of this study was to evaluate the microbial inhibitory activity and physicochemical quality of fresh carrot juice prepared with different environmentally-friendly washing methods during low temperature storage. Individual and combined treatments with sodium bicarbonate (baking soda, $NaHCO_3$) and citric acid were applied to carrots for 10 min. Tap water and 50 ppm of sodium hypochlorite (NaOCl) were used as the control. Combined treatment of 1% $NaHCO_3$ and 1% citric acid significantly reduced total aerobic counts and coliforms. In addition, combined treatment of 1% $NaHCO_3$ and 1% citric acid inhibited microbial growth for 7 days at $4^{\circ}C$ and $10^{\circ}C$ in a shelf-life study. There were no significant differences among the sanitizers in terms of $^{\circ}Brix$, acidity, pH, and color. Changes in physicochemical quality were not significantly different by sanitizer but were affected by storage temperature. These results indicate that washing with combined treatment of 1% $NaHCO_3$ and 1% citric acid is an effective method to inhibit the microbial population and maintain physicochemical quality. Therefore, combined treatment of 1% $NaHCO_3$ and 1% citric acid can be effectively used to sanitize and prepare carrot juice without affecting other properties.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.227-233
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• 2013

In this study, we evaluated the ability of various disinfectants to suppress the growth of microorganisms in fresh-cut products and organic vegetable. The growth of more than 50% of B. cereus isolates were suppressed by 50% ethanol, 0.1% hydrogen peroxide, 0.4% sodium hypochlorite or 1% calcium oxide. E. coli generally showed high susceptibility to concentration of 10% ethanol, 0.4% sodium hypochlorite and 1% calcium oxide. Eighty percent or more of S. aureus isolates exhibited resistance to ethanol, hydrogen peroxide and sodium hypochlorite, but the isolates were susceptible to concentrations of 1% calcium oxide. All isolates evaluated in this study were sensitive to benzalkonium chloride (BAC) and growth in the presence of $2.0{\mu}g/mL$ of BAC was completely inhibited. These pathogens showed widely different susceptibilities to different organic acids. Greater than 0.5% acetic acid and 2% and higher concentrations of malic acid and tartaric acid inhibited the growth of 60% of the isolates of B. cereus. Two percent acetic acid and tartaric acid inhibited 50% of the S. aureus isolates. Seventy percent of the E. coli isolates were resistant to malic acid and susceptible to 1% acetic acid and 10% tartaric acid. The antibacterial effects of the various sanitizers evaluated in this study were not only dependent on the type of disinfectant but also on the pathogen. Thus, it is important to select a sanitizer that is safe and effective at removing specific types of microorganisms.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.12
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• pp.1846-1853
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• 2010

The storage attributes of green juice prepared by washing Angelica keiskei with various washing solutions using air bubble method were investigated. The washing solutions were distilled water (DW), sodium hypochlorite electrolyzed water (SHEW), and slightly acidic electrolyzed water (SAEW). During storage at $4^{\circ}C$, the number of bacteria after 1 day was $>10^5$ CFU/mL when DW was used, whereas bacterial growth was $<10^5$ CFU/mL after 4 days when SHEW or SAEW was used. The pH and color were not changed, and the polyphenol content, electron donating ability and total antioxidant ability were decreased slowly with the increase of storage time. No significant difference in any of the measured properties was found among washing methods (p<0.05). Consequently, these results suggest the possible use of electrolyzed water for washing to enhance the shelf life of green juice with A. keiskei because SHEW and SAEW decreased bacterial growth without affecting other properties of the green juice.

• Restorative Dentistry and Endodontics
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• v.35 no.4
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• pp.295-301
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• 2010

Recent studies demonstrated that the combination of chlorhexidine (CHX) and sodium hypochlorite (NaOCl) resulted in the formation of a precipitate, para-chloroaniline (PCA). Alexdidine (ALX) is a kind of biguanides like CHX, and has stronger detoxification effect against the bacterial virulence factors such as lipoteichoic acid and lipopolysacchardide compared with CHX. The purpose of this study was to determine whether PCA was formed after chemical interaction between ALX and NaOCl using mass spectrometry. Mass spectrometry was performed for the mixture of five different concentrations of ALX (1, 0.5, 0.25, 0.125, 0.0625%) and 4% NaOCl. Results showed that the peak of PCA was not detected in mixed solutions of ALX and NaOCl in mass spectrometry analysis. The color of mixed solution of ALX and NaOCl after chemical interaction was light yellow to white, but there wasn't any precipitate found.