• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.831-836
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• 2004

Vibration of electric-powered hand grinder comes from the parts of motor, gear, bearing, and fan. Excessive vibration can be harmful to workers. To reduce vibration of a hand grinder we analyzed the frequency components from the routing electric-powered grinder and did modal test to find the natural frequencies of the each part. It shows that the vibration is due to the resonance of the case. To remove the resonance, the case structure is modified and the bearing cap is replaced on a basis of the results from the rotor dynamic analysis using SAMCEF. As a result the vibration of the hand grinder is reduced greatly.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.171-174
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• 2004

Superalloys with many strengthening alloying elements are frequently used in powder form to alleviate harmful effects of alloy segregation. HIP (hot isostatic pressing) and DB (diffusion bonding) as a form of solid-state bonding process is often used to make turbine components, such as integrated turbine rotors. HIP/DB process requires many technical overcomes related to dimensional changes as well as microstructural control. In this research, HIP/DB process for nickel base superalloys, Udimet 720, were investigated with a view to control the dimensional change during the consolidation process. Simple disc-shaped cans were used to select the conceptual die design for the control of the dimensional change especially in radial direction. The change in the shape of consolidated shape was investigated using commercial FE code with constitutive equations for low temperature plasticity and creep deformation.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.111-118
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• 2003

Recently, environmental damage to urban area becomes serious problem due to the exhaust emissions by increasing the number of vehicle. Especially, exhaust emission from diesel vehicles are blown to be harmful to human health and environment. Photoacoustic Spectroscopy system is very useful technology for simultaneous and continuous measurement of the various components of the automotive exhaust gas. In this study, in order to reduce emission gases from automobile, we tried to develop the measurement system of Photoacoustic Spectroscopy. To improve performance of high sensitive Photoacoustic Spectroscopy system for automotive exhaust emissions, the shape of Photoacoustic Spectroscopy cell was optimized to use the flow analysis. And Exhaust emission data of the 1,500cc gasoline engine was fixed the working fluid. The characteristics of fluid flow for cell were analyzed by various conditions in detail.

• Environmental Analysis Health and Toxicology
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• 제13권3_4호
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• pp.77-85
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• 1998

It is very frequent that LAS meets the chlorine bleaches not only in the processes but also in the path from the sewages to the rivers. Therefore, it is not difficult to imagine that the harmful substances like DBPs are produced when LAs reacts with free chlorine. THMs are the major components of DBPs which are formed by reactions of organic substances with the chlorine oxidants. Among them, chloroform is the most noteworthy material. Since the major behavior observed was the formation of chloroform during reaction of LAS with free chlorine, the models were developed to grasp the tendency of chloroform formation depending on condition. According to these models, the effect of pH in the formation of chloroform is most grave.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.373-375
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• 2003

The subway, a typical electrified transit, is operated by the 1500 V DC-powered system with the overhead positive feeder and the rails negative return. This return path would bring about considerable stray current circuits, that is, from the bottom of rails to sell and then to the station ground, unless the rail-to-soil resistance is sufficiently high. The stray current can cause electrolytic corrosion of subway metallic structures and adjacent underground utilities. In this paper, we reports on-site investigation of the stray current condition, especially influenced by drainage method. The drainage method including both forced drainage and polarized drainage, extensively adopted as a countermeasure for electrolytic corrosion of underground pipelines, was found out to exert a harmful influence upon rail components as well as the pipelines.

• ALGAE
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• 제28권4호
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• pp.297-305
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• 2013

There is increasing interest in the relationships between marine bacteria and red tide organisms. Some bacteria are known to kill red tide organisms, and may be responsible for accelerating the termination of red tides. Thus, certain algicidal bacteria have been proposed for the control of red tides. Meanwhile, many red tide organisms are known to feed on marine bacteria. The roles of marine bacteria and red tide organisms are therefore reversible. In Korean waters, the killing of red tide organisms by algicidal bacteria, and also the feeding of red tide organisms on marine bacteria have been extensively investigated. The findings of such studies may influence the conventional view of red tide dynamics, and also planktonic food webs. Here, we review the species and concentrations of algicidal bacteria that kill red tide organisms in Korean waters, as well as the ingestion rate and grazing impact of red tide organisms on marine bacteria. Furthermore, we offer an insight into the ecological roles of these 2 components in marine planktonic food webs.

• Tribology and Lubricants
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• 제34권6호
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• pp.292-299
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• 2018

The objective of this research is to investigate the impact of engine oil aging on PM(Particulate Matter), exhaust gases, and DPF. It is widely known that the specification of a lubricant and its consumption in an ICE considerably influences the release of regulated harmful emissions under normal engine operating conditions. Considering DPF clogging phenomena associated with lubricant-derived soot/ash components, a simulated aging mode is designed for DPF to facilitate engine dynamometer testing. A PM/ash accumulation cycle is developed by considering real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for ash accumulation. The test duration for DPF aging is approximately 300 h with high- and low-SAPs engine oils. Detailed engine lubricant properties of new and aged oils are analyzed to evaluate the effect of engine oil degradation on vehicle mileage. Furthermore, physical and chemical analyses are performed using X-CT, ICP, and TGA/DSC to quantify the engine oil contribution on the PM composition. This is achieved by sampling with various filters using specially designed PM sampling equipment. Using high SAPs engine oil causes more PM/ash accumulation compared with low SAPs engine oils and this could accelerate fouling of the EGR in the engine, which results in an increase in harmful exhaust gas emissions. These test results on engine lubricants under operating conditions will assist in the establishment of regulated and unregulated toxic emissions policies and lubricant quality standards.

• 한국의류산업학회지
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• 제23권6호
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• pp.844-851
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• 2021

Due to the increase in consumers' interest about well-being, interest in eco-friendly products has been increasing due to the harmful effects of various harmful substances contained in textile products and environmental issues. As a result, natural dyes of less potential risk than synthetic dyes and digital textile printing(DTP) textile products with less environmental pollution are drawing attention. However, due to the lack of evaluation criteria for DTP textile products with natural ink and the nature of many colors are stacked layer by layer for dying, the need for simultaneous analysis is emerging. To evaluate whether the natural dye is derived from natural ingredients, the biocarbon content is analyzed. However, in the case of ink made using natural dyes and DTP textile products using natural ink, it is difficult to analyze the biocarbon content due to the limitation of the presence of a small amount of dye contained therein. In this study, we were shown the possibility of natural derived verification by cross-checking the analytes of natural dyes (Persicaria tinctoria, an indigo dye; Dactylopius coccus, a light red; and Curcum longa L., i.e., turmeric) and natural ink with HPLC-MS/MS. The coefficient of determination was 0.999 or higher, the limit of quantification was 0.647-3.664 ㎍/L and a %RSD of each indicator material was less than 10. Then, the extraction amount of natural dyes for five patterned fabrics was analyzed.

• 한국식품영양학회지
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• 제36권3호
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• pp.193-201
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• 2023

Prebiotics are known as components of intestinal microbiota that can improve and maintain human health status by stimulating the growth and activity of the intestinal tract as a method of controlling the intestinal environment. In this study, we examined whether 2'-fucosyllactose (FL) could affect intestinal microbial population and bowel activity. Water content and frequency of mouse feces were increased in the 2'-FL treated group at a high concentration (1,000 mg/kg), with brightness of the color enhanced and physical properties diluted. In addition, intestinal microbial analysis showed that harmful bacteria Clostridium and Staphylococcus strains were decreased and beneficial bacteria such as Lactobacillus strains were markedly increased in the group treated with a high concentration of 2'-FL compared to those in the control group. These findings suggest that administration of 2'-FL can maintain healthy bowel activity by reducing harmful bacteria population and improving diluted physical properties.

• 생명과학회지
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• 제23권5호
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• pp.664-668
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• 2013

본 연구에서는 흰점박이꽃무지 유충의 식 약용으로써의 가능성을 제시하기 위해 영양성분분석 및 유해물질 검사를 실시하였다. 일반성분은 건량 기준 조단백질 함량이 57.86%로 매우 높았으며, 조지방 16.57%, 조섬유 8.36%, 조회분 5.38%로 구성됨을 확인하였다. 또한 불포화 지방산 중 혈압강하작용 및 여러 약리기전이 알려져 있는 oleic acid (omega-6)가 전체지방산 중 60% 이상을 차지하고 있었고, linoleic acid (omega-6) 5.22%, arachidonic acid (omega-6) 0.25% 함유되어 있었다. 유해물질의 분석 결과, 중금속의 일종인 수은이 0.07 mg/kg으로 존재하였으나 일반식품(어패류의 경우, 0.5 mg/kg) 허용 기준치 이하의 미량인 것으로 확인되었으며, 병원성 미생물인 대장균 O157:H7과 살모넬라균은 검출되지 않았으므로 식용으로 사용하기에 문제가 없는 것으로 판단되었다. 따라서 흰점박이꽃무지 유충은 고함량의 단백질과 필수아미노산 및 생체 내에서 합성할 수 없는 영양소들을 다량 함유하고 있으므로 육류나 어류를 대신할 수 있는 대체식품으로 활용 가능할 것으로 판단되며 안전한 식품소재로의 기준 및 규격마련을 통해 식 약용으로 이용 가능할 것이라 기대된다.