PURPOSES : The aim of this study is to review freeze-and-thaw testing apparatuses, develop a freeze-and-thaw testing setup with a test protocol, test the freeze-and-thaw properties of soils collected from different parts of South Korea, and suggest an index for frost susceptibility criteria for soils found in South Korea. METHODS : Based on a literature review, a new freeze-thaw testing setup was developed. In addition, a test protocol was developed for freeze-thaw testing. Soils collected from different parts of South Korea and bedding sand used for block pavements were tested to determine whether the measurements from the newly developed test setup could capture important freeze-thaw characteristics of the soils. Finally, to develop local frost susceptibility criteria, a parameter including both the vertical deformation and thermal conductivity characteristics of the soils was suggested. RESULTS : The results from the laboratory experiments indicate that the newly developed freeze-and-thaw setup captures the required parameters to quantify the responses of soils subjected to cyclic freeze-and-thaw testing. In addition, a vertical deformation of up to 2.437 mm is measured. Moreover, seven soils out of the nine tested soils are classified as having a medium frost susceptibility, whereas the remaining two show low frost susceptibility. The bedding sand experiment also shows that there is a possibility of having a frost susceptible condition based on the moisture content. When submerged, the bedding sand is classified as having a medium frost susceptibility. CONCLUSIONS : The "HEART" freeze-thaw testing setup was able to capture the parameters required for evaluating the frost susceptibility of soils. This setup and testing procedure could be further used to test and prepare criteria for classifying the frost susceptibility of soils found in South Korea.

Recently, phosphine resistance of Sitophilus oryzae has been reported from China, India, Brazil and Australia. In this study, susceptibility of three fumigants were assesses on phosphine resistant and susceptible S. oryzae to investigate domestic phosphine resistance level and to use base data for resistance control. On susceptible insects, LCT50 of phosphine was 0.440mg h/L for egg, 0.602mg h/L for early larvae, 3.901mg h/L for late larvae, 6.171mg h/L for pupae and 0.295mg h/L for adult stage, respectively. LCT50 of methyl bromide was 9.997mg h/ L for egg, 12.113mg h/L for early larvae, 18.952mg h/L for late larvae, 21.104mg h/L for pupae and 17.824mg h/L for adult stage, respectively. LCT50 of ethyl formate was 75.795mg h/L for egg, 60.110mg h/L for early larvae, 160.491mg h/L for late larvae, 255.797mg h/L for pupae and 77.711mg h/L for adult stage, respectively. On resistant insects, LCT50 of phosphine was 6.959mg h/L for egg, 28.456mg h/L for early larvae, 48.170mg h/L for late larvae, 29.106mg h/L for pupae and 16.550mg h/L for adult stage, respectively. LCT50 product of methyl bromide was 17.842mg h/L for egg, 14.900mg h/L for early larvae, 25.840mg h/L for late larvae, 43.520mg h/L for pupae and 16.397mg h/ L for adult stage, respectively. LCT50 of ethyl formate was 60.034mg h/L for egg, 64.450mg h/L for early larvae, 149.028mg h/L for late larvae, 140.408mg h/L for pupae and 66.043mg h/L for adult stage, respectively. Domestic resistant S. oryzae showed 4 to 56 times higher resistance rate than susceptible insects.

목적 : Coagulase-negative Staphylococci 분리 균주에 대한 quinolone 계열 및 그람양성균에 효과적인 vancomycin과 erythromycin 항생제 감수성 정도를 알아보고 DNA gyrase 유전자를 분석하고자 한다. 방법 : 세균성 각막염이 의심되는 사람의 각막에서 검출한 Coagulase-negative Staphylococci 6 균주를 대상으로 ofloxacin, ciprofloxacin, levofloxacin, vancomycin, erythromycin 항생제 감수성을 실시한 후 각 균주들의 genomic DNA를 추출하여 PCR 증폭한 후 gyraseA 유전자의 DNA를 분석하였다. 결과 : 항생제 감수성 검사에서 S. epidermidis (SE-2, SE-3), S. hominis (SH-1) 그리고 S. saprophyticus (SS-1) 균주에서는 ofloxacin, ciprofloxacin, levofloxacin, vancomycin 감수성, erythromycin 내성으로 나타났으며, 나머지 균주에서는 모두 감수성으로 나타났다. gyraseA 유전자 분석에서는 S. epidermidis (SE-1) 균주에서 Met75→Thr, Met93→Val 으로 아미노산 이중 mutation이 관찰되었으며, S. warneri (SW-1)와 S. saprophyticus (SS-1) 균주에서는 다수의 silent mutation이 관찰되었다. 결론 : Coagulase-negative Staphylococci 분리균주에서 erythromycin 항생제의 내성이 있다는 것을 확인 할 수 있었으며, gyraseA 유전자 분석결과 아미노산 이중 mutation 및 silent mutation이 관찰되었다. 따라서 지금은 내성이 아니지만 silent mutation이 언제든지 내성을 일으킬 수 있을 것으로 생각된다.

PURPOSES: It is theoretically well known all over the world, that porous hot mixed asphalt (HMA) with hydrated Lime improves moisture and rutting resistance, and reduces pothole occurrence frequency, as well as the life cycle cost (LCC). METHODS : Addictive in the two different formations of the liquid anti-stripping Agent and powder Hydrated-Lime was applied in this investigation in order to obtain relatively clear results according to their types and conditions. Firstly, the moisture conditions were set, and applied to the porous HMA mixtures with hydrated lime (anti-stripping agent). Next, it was followed by a non-destructive test with the application of three freeze-thaw cycles, which were individually carried out thrice to compare the results of the dynamic moduli. Lastly, the hydrated lime effect related to moisture sensibility to porous HMA has been verified through the analysis of the modulus results regarding the change rate of dynamic modulus per n-cycle. RESULTS: It is clear from this investigation, that the dynamic modulus is inversely proportional to the change in temperature, as the graph representing the rigidity of the thermorheologically simple (TRS) material showed gradual decline of the dynamic modulus with the increase in temperature. CONCLUSIONS: The porous HMA mixture with the anti-stripping agent (hydrated Lime) has been found to be more moisture resistant to freezing and thawing than the normal porous HMA mixture. It is clear that the hydrated lime helps the HMA mixture to improve its fatigue resistance.

목 적: 콘택트렌즈 케이스에서 분리한 균주들을 동정하고, Serratia marcescens 균주들에 대해 항생 제 감수성 검사를 시행하였다. 방 법: 총 65개의 콘택트렌즈 케이스를 수거하여 분리한 균주들을 16s rRNA gene 염기서열을 분석하여 동정하였고, Serratia marcescens 균주들을 Nalidixic acid(30㎍), Ciprofloxacin(5㎍), Ofloxacin(5㎍), Levofloxacin(5㎍) 항생제를 이용하여 디스크 확산법으로 항생제 감수성 검사를 실시하였다. 결 과: 30개의 콘택트렌즈 케이스에서 세균이 검출되었으며, 균주로는 Achromobacter sp. 8균주, Achromobacter xylosoxidans 3균주, Achromobacter spanius 1균주, Pandoraea pnomenusa 1균주, Serratia marcescens 17균주가 동정되었다. Serratia marcescens 균주에 대한 항생제 감수성 검사에서는 Nalidixic acid, Ciprofloxacin, Ofloxacin, Levofloxacin 모두 감수성으로 나타났다. 결 론: 콘택트렌즈 케이스에서 분리한 균주들을 16S rRNA gene 염기서열을 분석하여 동정한 결과 모두 30 균주가 동정되었으며, 콘택트렌즈 케이스에서 많이 분리 동정된 Serratia marcescens 균주에 대한 Quinolone 계 항생제 감수성 검사에서 모두 감수성으로 나타났다. 그러나 항생제의 지속적인 사용으로 내성 균주들이 나타날 것으로 예측되며 Quinolone 항생제의 내성 발생률에 대한 체계적인 연구와 관리가 필요한 것으로 사료된다.

PURPOSES : The purpose of this paper is to evaluate the moisture susceptibility of asphalt mixtures containing developed liquid antistripping agents using the boiling water test as a screening test. METHODS: The boiling water test was used to evaluate the moisture susceptibility of asphalt mixtures containing different anti-stripping agents. The tensile strength ratio was calculated to compare the moisture susceptibility of the asphalt mixtures after indirect strength tests were performed. Additionally, image analysis techniques were used to calculate and analyze the quantity of stripped area in the asphalt mixtures. RESULTS: In general, the asphalt mixtures containing anti-stripping agents showed a higher resistance of anti-stripping based on the boiling water test and tensile strength ratio. CONCLUSIONS: The boiling water test can be used to differentiate the resistance of moisture susceptibility of asphalt mixtures, except for asphalt mixtures containing hydrated lime. The boiling water test can be used as a screening test for asphalt mixtures before conducting time consuming and expensive indirect tensile strength tests.