Microstructure, Tensile and Fatigue Properties of Al–5 wt.%Mg Alloy Manufactured by Twin Roll Strip Casting

Joon‑Young Heo,Min‑Seok Baek,Kwang‑Jun Euh,Kee‑Ahn Lee 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.5

This study investigated the microstructure, tensile and fatigue properties of Al–5 wt.%Mg alloy manufactured by twin rollstrip casting. Strips cast as a fabricated (F) specimen and a specimen heat treated (O) at 400 °C/5 h were produced andcompared. In the F specimen, microstructural observation discovered clustered precipitates in the center area, while in theO specimen precipitates were relatively more evenly distributed. Al, Al 6 (Mn, Fe), Mg 2 Al 3 and Mg 2 Si phases were observed. However, most of the Mg 2 Al 3 phase in the heat-treated O specimen was dissolved. A room temperature tensile test measuredyield strength of 177.7 MPa, ultimate tensile strength of 286.1 MPa and elongation of 11.1% in the F specimen and167.7 MPa (YS), 301.5 MPa (UTS) and 24.6% (EL) in the O specimen. A high cycle fatigue test measured a fatigue limit of145 MPa in the F specimen and 165 MPa in the O specimen, and the O specimen achieved greater fatigue properties in allfatigue stress conditions. The tensile and fatigue fracture surfaces of the above-mentioned specimens were observed, and thisstudy attempted to investigate the tensile and fatigue deformation behavior of strip cast Al–5 wt.%Mg based on the fi ndings.

다변량 분석법을 이용한 소양강댐 상류 유역의 하천 수질 평가

최한규,백효선,허준영 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.A

The object of this study is to evaluate the factors affecting the water quality and to propose the influence of dominant factor quantitatively. The correlation analysis was performed to know the correlationship among the water quality items. As a result of partial correlation analysis, it was shown that the water quality items are affected by the rainfall item directly. The factor analysis was performed to grasp some number of factors on each point for deducing the items of similar variable characteristics. The four points were divided into different factor groups. It was grasped that NH_3-N and NO_3-N items have different variable characteristics after comparing the items. The Multiple regression analysis can decrease the number of observation. In the deduced multiple regression formula, it was shown that the rate of T-N, NH_3-N and NO_3-N in the independent variable took about 60% among all the regression formulas.

제주 차귀도 연안해역 미생물 분포 및 이화학적 특성

문영건,김만철,이준백,송춘복,여인규,김종만,박근태,손홍주,최우봉,허문수 한국환경과학회 2006 한국환경과학회지 Vol.15 No.3

산불진화정보 관리를 위한 Mobile GIS 공간 데이터 압축기법 개발

조명희,이명보,이시영,김준범,권봉겸,허영진 한국지리정보학회 2004 한국지리정보학회지 Vol.7 No.2

최근 무선 인터넷 및 통신기술의 눈부신 발달과 LBS(location based service)개념을 기반으로 한 mobile GIS 기술 개발은 대규모 산불 발생시 정확한 현장 파악과 신속한 상황보고 뿐만 아니라 사고 예방과 분석·평가에 이르기까지 의사결정지원시스템으로 자리를 잡고 있다. 본 연구에서는 지상진화대의 정확한 위치와 이동상황을 실시간으로 파악하여 안전한 진화작업 유도 및 산불진화 환경정보를 제공을 목적으로 mobile GIS 기술 기반의 산불진화정보 관리시스템을 설계하고 네트워크 부하감소를 위하여 '.gci'라는 공간 데이터 압축기법을 개발하여 면, 선, 주기 데이터에 대하여 51~62%의 높은 압축률을 구현하였다. 따라서 대규모 산불 발생시 일어날 수 있는 안전사고를 미연에 방지하고 사고 발생시 신속한 후속조치로 안전하고 과학적인 산불진화 업무를 수행할 수 있도록 하였다. Recently GPS and mobile GIS technologies based on LBS (location based service) have played an important role as DSS (decision supporting system) for domestic forest fire extinguishment policies. In this study forest fire extinguishments information management system based on mobile GIS technique was designed to seize the exact location on wireless network so that it helps to guide the safe and efficient extinguishments affairs and provide the extinguishments environment toward ground fighting teams and the central forest government in real time. Moreover, possibly to operate this system, the foundation technologies by the name of `. gci such as the spatial data compression method, the spatial data transmission method over wireless network and the spatial analysis interface on PDA should be mainly considered. Especially, in this study the spatial data compression method having high compression rate from 51% to 62% for each polygon, line, and point data, without the loss of data was developed.

Fosfomycin의 항균효과 및 capillary electrophoresis에 의한 측정법에 관한 연구

윤효인,박승춘,이규승,권진욱,조준형,신광순,김무열,허강준,조명행 충남대학교 수의과대학 동물의과학연구소 1996 動物醫科學硏究誌 Vol.4 No.-

Fosfomycin, a low molecular antibiotic, is to be easily synthesized, therefore to be possibly used in veterinary sectors due to econimic reasons. In this study, we determined the antibacterial activities of fosfomycin against some domestic animal-origin pathogens, and its combined effects with some important antibacterials available. We also compared detection methods of fosfomycin from various measuring instruments. The results obtained through this experiment were as follows: 1. Antibacterial activities of fosfomycin against the pathogens used in this experiment were appeared fairly low. We found the antobacterial activities depanded on the kinds of media and the addition of some material thereins, which suggests the importance of appropriate medium so as to judge the antibacterial activity of fosfomycin. 2. Fosfomycin showed varying antibacterial effects in combination with other antibacterials, which should be taken into consideration when combining other antobacterials especially in the clinical settings. Of the combined antivacterials, fosfomycin had synergistic effects in combination with amoxicillin but antagonistic effects with oxytetracyline. 3. Conventional detection methods using HPLC, GC and spectrophotometer were not appropriate to measure fosfomycin. Capillary electrophoresis by the way of the indirect ultraviolet detection method was good enough to detect fosfomycin in the range of expected concentration in tissues, with the limit of quantitation (LOQ) of 1.25 ㎍/㎖. We recommend the eletrophoresis method could be used to detect fosfomycin, thereby being able to set the optimal dosage for animals and providing the measures in relation with the residual concentration in the meat.

A new methodology for measuring coastline recession using buffering and non-linear least squares estimation

Heo, Joon,Kim, Jung Hwan,Kim, Jin Woo Taylor Francis 2009 International Journal of Geographical Information Vol.23 No.9

<P> Coastline recession is one of the best indicators of coastal erosion. Three methods for computing coastline recession - the baseline approach, the dynamic segmentation approach and the area-based approach - have been used, each of which has one or more drawbacks. To overcome these problems, a new methodology for measuring coastline recession is proposed, using buffering and non-linear least squares estimation. The proposed method was compared with the three existing methods with respect to two simulated cases and two real coastlines. Test results confirmed that the new method is more reliable than the three other methods, all of which are susceptible to variability of recession, scale, number of line segments, length of coastlines and direction of the baseline. The proposed method, incorporating two physically meaningful values - magnitude and variability of coastline recession according to the mean and standard deviation of coastline offsets, respectively - presents itself as an effective alternative method of assessing coastline recession.</P>

Comparison of filtration performance of commercially available automotive cabin air filters against various airborne pollutants

Heo, Ki Joon,Noh, Jung Woo,Lee, Byung Uk,Kim, Yeonsang,Jung, Jae Hee Elsevier 2019 Building and environment Vol.161 No.-

<P><B>Abstract</B></P> <P>Controlling air pollutants in the automobile cabin environment has become increasingly important owing to the health risks of exposure to high concentrations of harmful air pollutants. To protect daily commuters and drivers against the harmful effects of air pollution, modern automobiles are commonly equipped with automotive cabin air filters (ACAFs). Thus, understanding the filtration performance of ACAFs is essential for assessing cabin indoor air quality. In this study, six original equipment manufacturer (OEM) and nine after-market ACAFs were selected and their particulate matter (PM) filtration performance against standard particle (ISO 12103-1 A2 dust), filter pressure drop under various airflow velocities, and gas removal performance against standard test gases (<I>n</I>-butane and toluene) were estimated. In the PM filtration test, the lowest filtration performance occurred at a particle size range of 0.3–0.5 μm, with a filtration efficiency of 50–90%, and the filtration performance increased with increasing particle size. The PM filtration performance of OEM ACAFs (72.3 ± 13.81%) was higher than that of after-market ACAFs (56.4 ± 23.72%). All test OEM ACAFs satisfied the Korea Air Cleaning Association standard filtration performance guidelines for 0.3–0.5-μm particles (>50%), but four of the nine after-market ACAFs did not satisfy the standard guidelines. In addition, only one of the six OEM ACAFs simultaneously satisfied the standard removal performance guidelines for <I>n</I>-butane (>70% after 1 min and >45% after 5 min) and toluene (>80% after 1 min and >70% after 5 min). This study provides valuable baseline information on ACAFs for understanding and improving cabin indoor air quality.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Commercial automotive cabin air filters (ACAFs) were evaluated and compared in terms of filtration and removal performance. </LI> <LI> Eleven of the 15 ACAFs tested satisfied the standard guidelines for PM filtration performance. </LI> <LI> Only one ACAF satisfied the standard guidelines for gas removal performance of both <I>n</I>-butane and toluene. </LI> <LI> The filtration performance of ACAFs varied depending on the type of filter (OEM or after-market filter). </LI> <LI> Careful selection of commercial ACAFs based on performance is essential to protect cabin indoor air quality. </LI> </UL> </P>

Efficacy and safety of norfloxacin for the control of bacterial diseases in eel (Anguilla japonica)

Heo, Gang-joon The Korean Society of Veterinary Science 1999 大韓獸醫學會誌 Vol.39 No.2

A study on quinolone antibacterial, norfloxacin, was performed to apply for the control of bacterial diseases in eel (Anguilla japonica). Norfloxacin was proved excellent in antibacterial activity and sensitivity against fish bacterial pathogens when compared with the existing antibacterials and antibiotics. And any side effect was not observed during the period of indicated use. An outline of minimal inhibitory concentration was $0.03{\sim}0.1{\mu}g/ml$, $TLm_{48h}$ value was 3,500mg/l. The residual time of the day in fish body was less than 17 days and any pathological changes were not observed. The study has revealed that norfloxacin can be applied to treat some fish bacterial disease by the dosage of 100g/day/ton of fish body weight for about 3 days perorally. Further, norfloxacin may be used for the control of bacterial pathogens in eel.

New Line Accuracy Assessment Methodology Using Nonlinear Least-Squares Estimation

Heo, Joon,Woo Kim, Jin,Sang Park, Ji,Sohn, Hong-Gyoo American Society of Civil Engineers 2008 Journal of surveying engineering Vol.134 No.1

Gold “Nanograils” with Tunable Dipolar Multiple Plasmon Resonances

Heo, Chul-Joon,Kim, Se-Heon,Jang, Se Gyu,Lee, Su Yeon,Yang, Seung-Man WILEY-VCH Verlag 2009 Advanced Materials Vol.21 No.17

<B>Graphic Abstract</B> <P>Gold “nanograils”, novel plasmonic nanostructures that can be represented as three different-sized rings connected vertically by curved surfaces, similar to a miniaturized grail, are presented. Reflectance measurements and FDTD simulations demonstrate the existence of strong multiple plasmon resonances with the same dipolar symmetry around the sharp ring edges of the nanograils. <img src='wiley_img/09359648-2009-21-17-ADMA200802776-content.gif' alt='wiley_img/09359648-2009-21-17-ADMA200802776-content'> </P>