• 한국환경과학회지
• /
• 제22권12호
• /
• pp.1661-1669
• /
• 2013

This study conducted a laboratory simulation using artificial and natural rainfall in order to investigate the runoff characteristics of livestock resources through the analysis of the surface runoff water and infiltration water by rainfall intensity and fertilization level. Cattle manure and pig liquid fertilizer was used as livestock resource. As a result of this study, it was observed that the surface runoff occurred over 32 mm/hr rainfall intensity, and flow rate of the surface runoff water and the runoff ratio of contaminant parameters from livestock resource was increased, as rainfall intensity was stronger. With doubled fertilization level, T-N increased in compost and the amount of $COD_{Mn}$ runoff also considerably increased in liquefied fertilizer. In the case of natural rainfall, the runoff ratio of T-P clearly increased in compost and the T-N of final surface runoff ratio in compost and liquefied fertilizer was ranged from 0.13047 to 0.13623 with stronger rainfall intensity.

• 한국산업보건학회지
• /
• 제24권2호
• /
• pp.169-181
• /
• 2014

Objectives: The purpose of this study was to obtain information regarding classification and health hazards that may result from a 13-week inhalation exposure to 2-methylpentane by Sprague-Dawley rats. Materials: The testing method was conducted in accordance with OECD guidelines for the testing of chemicals No. 413. The rats were divided into four groups(ten male and ten female rats in each group) and exposed to 0 ppm, 290 ppm, 1,160 ppm, 4,640 ppm 2-Methylpentane in each exposure chamber for six hours per day, five days per week, for 13 weeks. Results: No death or particular clinical presentation including weight change and change of feed rate was observed. The relationships between dose, gender and response were also not significantly changed in urinalysis, hematologic examination, or biochemical examination of blood(except for total cholesterol being up, total protein being up, and chloride ion being down in males), and blood coagulation time. For the relative weight measurement of organs, in the male group the weight change of both kidney and liver were increased in proportion to dose. In histopathological examination, nephropathy in the kidney(cystic change of renal tubules, regenerative tubule, inflammatory cell infiltration and necrosis in the interstitial tissue) was increased in a dose-dependent manner in the male group(290 ppm, 1,160 ppm, 4,640 ppm). However, other organs were not affected by the test substance. Conclusions: 2-methylpentane was estimated as a chemical causing nephropathy in the male group. NOAEL(No Observable Adverse Effect Level) in the female group is more than 4,640 ppm, while inthe male group it is less than 290 ppm.

• Archives of Plastic Surgery
• /
• 제33권5호
• /
• pp.621-626
• /
• 2006

Purpose: Erythropoietin is traditionally known to regulate erythropoiesis, but recently its protective effect against ischemia-reperfusion injury has been studied mainly in cardiovascular and neuronal systems. This study was planned to investigate the effects of recombinant human erythropoietin on ischemia-reperfusion injury in rat TRAM flap model. Methods: Superiorly based TRAM flap was elevated and ischemic insult was given for four hours. Thirty minutes before reperfusion, single dose recombinant human Erythropoietin(5000IU/kg) was injected via intraperitoneal route in the treatment group. At 24 hours postoperatively, systemic neutrophil count, tissue myeloperoxidase activity, malonyldialdehyde amount, nitric oxide content, tissue water content and histologic finding of inflammation was evaluated. On 10 days postoperatively, flap survival rate, angiogenesis and change in hematocrit level was evaluated. Results: Tissue nitric oxide level was significantly higher and myeloperoxidase activity was significantly lower in the treatment group 24 hours after reperfusion. Tissue water content was significantly lower in the treatment group. Perivascular neutrophil infiltration and intravascular adhesion was marked in the control group. Mean flap survival after ten days was 69% in the treatment group, and 47% in the control group, demonstrating a significant difference. Neovascularization in the treatment group also outnumbered the control group. No significant hematocrit rise was noted ten days after erythropoietin administration. Conclusion: Recombinant human Erythropoietin improved flap survival in ischemia-reperfusion injured rat TRAM flaps, at least partially owing to suppressed inflammation, increased nitric oxide, and enhanced angiogenesis.

• 화약ㆍ발파
• /
• 제34권4호
• /
• pp.1-9
• /
• 2016

수중 강재 절단을 위해 내압성, 유연성의 외부장치인 스프링 호스와 가소성 성형폭약을 결합한 수중 성형폭약 장치를 고안하였다. 최적조건 설계를 위한 기초실험으로 외부장치의 형상에 따른 관입성능을 비교하였다. 실험결과를 평가하기 위하여 관입 된 강재에 액상 고무를 이용하여 모형을 획득한 후 이미지 분석을 하였고, 성형폭약의 관입 과정을 모사하기 위해 AUTODYN 프로그램을 이용하여 해석하였다. 분석결과 원형 및 사각 외부장치의 평균 관입 깊이는 유사하였으나 관입품질은 원형의 경우 더 균일하였다. 또한, 사각의 경우 침투현상이 발생하였고, 수압증가에 따른 변위가 원형대비 크게 측정되었다.

• 유기물자원화
• /
• 제16권1호
• /
• pp.46-52
• /
• 2008

자연계로 유출된 유류 및 유기용매 등 비수용성액체는 토양공극사이에 존재하며 서서히 용해되면서 지속적인 수질오염원으로 작용한다. 본 연구는 유리로 제작된 다공성매체 실험장치를 이용하여 토양 공극사이에 위치한 비수용성액체의 용해현상을 시각화하였고, 이미지 분석기술을 이용하여 용해속도를 정량화하였다. 다공성매체 공극사이 TCE는 물의 유량을 빠르게 할수록 용해속도가 증가하는 것으로 나타났다. 이는 TCE로 오염된 지역의 강우량이 많거나, 지하수 유속이 빠른 지역일 경우 토양내 TCE 제거는 용이하게 일어날 수 있지만, 용해된 TCE의 지하수 유입으로 증가한다는 점을 시사한다. 다공성매체 공극사이 TCE의 현미경 이미지 관측결과, 물의 유량이 빠른 경우 역시 TCE blob 수가 급격히 감소함을 확인하였다. 물의 흐름이 용이한 우선흐름경로에 존재하고 있는 TCE는 물과의 용이한 접촉으로 용해가 빠르게 진행되었다. 반면 정체구역에 존재하는 TCE의 용해속도는 매우 느리게 나타났다. 현장 토양에서도 동일한 현상이 일어날 것이므로 지하수 조사결과 TCE의 검출이 계속된다면, 토양 공극사이에 여전히 TCE가 존재하고 있음을 암시하므로 이에 대한 대책이 강구되어야 한다.

• The Korean Journal of Pain
• /
• 제31권2호
• /
• pp.93-101
• /
• 2018

Background: Magnesium is one of the effective, safe local anesthetic adjuvants that can exert an analgesic effect in conditions presenting acute and chronic post-sternotomy pain. We studied the efficacy of continuous infusion of presternal magnesium sulfate with bupivacaine for pain relief following cardiac surgery. Methods: Ninety adult patients undergoing valve replacement cardiac surgery randomly allocated into three groups. In all patients; a presternal catheter was placed for continuous infusion of either 0.125% bupivacaine and 5% magnesium sulfate (3 ml/h for 48 hours) in group 1, or 0.125% bupivacaine only in the same rate in group 2, versus conventional intravenous paracetamol and ketorolac in group 3. Rescue analgesia was iv $25{\mu}g$ fentanyl. Postoperative Visual Analog Scale (VAS) and fentanyl consumption during the early two postoperative days were assessed. All patients were followed up over two months for occurrence of chronic post-sternotomy pain. Results: VAS values showed high significant differences during the first 48 hours with the least pain scale in group 1 and significantly least fentanyl consumption ($30.8{\pm}7{\mu}g$ in group 1 vs. $69{\pm}18{\mu}g$ in group 2, and $162{\pm}3$ in group 3 respectively). The incidence of chronic pain has not differed between the three groups although it was more pronounced in group 3. Conclusions: Continuous presternal bupivacaine and magnesium infusion resulted in better postoperative analgesia than both presternal bupivacaine alone or conventional analgesic groups.

• 한국농공학회논문집
• /
• 제53권6호
• /
• pp.129-136
• /
• 2011

To measure effects of surface cover on runoff and sediment discharge reduction using rainfall simulator, four(5 m${\times}$30 m scale) plot experiments were conducted in this study. Surface covers made with straw mat, Polyacrylamide (PAM), chaff, and sawdust were simulated 4 times under 31.1~44.4 mm/hr rainfall intensities. Compared with results from control plot, the time of runoff generation is delayed and outflow volume decreased with surface cover. Effects on runoff reduction of straw mat, PAM, sawdust and chaff ranged 4.7~81.5 % and runoff rate reduced by 6.5~76.1 % respectively, when compared with those from control plot. The percentage of decrease in sediment discharge were 99.7~99.8 % from straw mat+sawdust+PAM plots, 85.9~95.6 % from straw mat+PAM plots, and 98.5~99.4 % from straw mat+chaff+PAM plots. The runoff, sediment discharge, and SS concentration reduction efficiencies of the cover materials were outstanding when compared to control plot. It was analyzed that reduction of runoff and sediment discharge were mainly contributed by decrease in rainfall energy impact and flow velocity and increase of infiltration due to the surface cover materials. The results could be used as a base for the development of best management practices (BMPs) to reduce runoff, sediment discharge from sloping field.

• Journal of Microbiology and Biotechnology
• /
• 제29권11호
• /
• pp.1707-1716
• /
• 2019

The development of new antimicrobial agents is essential for the effective treatment of diseases such as sepsis. We previously developed a new short peptide, Pap12-6, using the 12 N-terminal residues of papiliocin, which showed potent and effective antimicrobial activity against multidrug-resistant Gram-negative bacteria. Here, we investigated the antimicrobial mechanism of Pap12-6 and a newly designed peptide, Pap12-7, in which the 12^th Trp residue of Pap12-6 was replaced with Val to develop a potent peptide with high bacterial selectivity and a different antibacterial mechanism. Both peptides showed high antimicrobial activity against Gram-negative bacteria, including multidrug-resistant Gram-negative bacteria. In addition, the two peptides showed similar anti-inflammatory activity against lipopolysaccharide-stimulated RAW 264.7 cells, but Pap12-7 showed very low toxicities against sheep red blood cells and mammalian cells compared to that showed by Pap12-6. A calcein dye leakage assay, membrane depolarization, and confocal microscopy observations revealed that the two peptides with one single amino acid change have different mechanisms of antibacterial action: Pap12-6 directly targets the bacterial cell membrane, whereas Pap12-7 appears to penetrate the bacterial cell membrane and exert its activities in the cell. The therapeutic efficacy of Pap12-7 was further examined in a mouse model of sepsis, which increased the survival rate of septic mice. For the first time, we showed that both peptides showed anti-septic activity by reducing the infiltration of neutrophils and the production of inflammatory factors. Overall, these results indicate Pap12-7 as a novel non-toxic peptide with potent antibacterial and anti-septic activities via penetrating the cell membrane.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
• /
• pp.726-731
• /
• 2002

Reaction synthesis is a process to form ceramics, intermetallics and their composites from elemental powder mixture. Application of this process to a surface modification techniques has a possibilities to enable the process at a lower temperature or for a shorter time, although synthesized materials are likely to include voids and unreacted elements. This paper intend to examine the effect of Si addition to the mixture of Al and Ni on the densification of synthesized Ni-Al intermetallic compounds and to evaluate the surface properties of obtained coatings. By the Si addition, exothermic reaction temperature to form Ni-Al intermetallic was lowered to be below the melting point of Al. Si soluted $Al_3$Ni$_2$, $Al_3$Ni and $Al_{6}$Ni$_3$Si were mainly formed in the coating layer when powder mixture was heated to 973K for 300s. Besides, densification was enhanced by increasing hot press pressure, Si additions and heating rate. When the composition of eutectic Al-Si reaches 78%, void ratio of sintered compact reduced to 0.4%. It is caused by higher flowability of Al-Si liquid phase generated and its infiltration into the void. Since the hardness of NiAl(Si) compound (about 600HV) formed in the coating layer is higher than that of Ni-Al compound (about 400HV), coating layer with high density and superior wear property is obtained by hot press using reaction synthesis from Al-Ni-Si powder mixture.

• 한국물환경학회지
• /
• 제36권2호
• /
• pp.109-115
• /
• 2020

Recently, since impervious areas have increased due to urban development, the water cycle system of urban watersheds has been destructed. Hence, researches on LID (Low Impact Development) technique have been conducted to solve such problems environmentally. In order to verify suitability with the scale and arrangement of LID technique, the runoff reduction effect of the LID technique should be analyzed per small watershed unit. In this study, pre-post difference of the runoff by applying the LID was estimated using the rational method and rainwater treatment capacity equation. As a result, the runoff before and after the application of LID were estimated as 22,533.5 ㎥ and 14,992.1 ㎥, respectively. In addition, rainfall-runoff simulations were carried out using SWMM to evaluate the efficiency of the LID technique. The SWMM simulation results showed that the runoff before and after the application of LID were 21,174 ㎥ and 15,664 ㎥, respectively. Based on the results of the two methods, the scale and arrangement of the LID technique were revised in order to maximize the effect of the water cycle improvement. Rainfall-runoff simulations were carried out using the SWMM with the revised LID techniques. As a result, despite 34.8 % reduction of pervious pavement area, the rate of runoff reduction increased by 2.1 %. These results indicate that designing the scale and arrangement of LID technique, while considering the total amount of inflow entering into each LID techniques, is essential to effectively achieve the goals of runoff reduction in urban development.