PURPOSES : It is well known that low temperature cracking is one of the most serious distresses on asphalt pavement, especially for northern U.S. (including Alaska), Canada and the northern part of south Korea. The risk of thermal cracking can be numerically measured by estimating thermal stress of a given asphalt mixture. This thermal stress can be computed by low temperature creep testing. Currently, in-direct tensile (IDT) mixture creep test mentioned in AASHTO specification is used for measuring low temperature creep properties of a given asphalt mixture. However, IDT requires the use of expensive testing equipment for performing the sophisticated analysis process, however, very few laboratories utilize this equipment. In this paper, a new and simple performance test (SPT) method: bending beam rheometer (BBR) mixture creep testing equipment is introduced, and the estimated experimental results were compared with those of conventional IDT tests. METHODS: Three different asphalt mixtures containing reclaimed asphalt pavement (RAP) and roofing shingles were prepared in the Korea Expressway Corporation (KEC) research laboratory. Using the BBR and IDT, the low temperature creep stiffness data were measured and subsequently computed. Using a simple power-law function, the creep stiffness data were converted into relaxation modulus, and subsequently compared. Finally, thermal stress results were computed from relaxation modulus master curve using Gaussian quadrature approach with condierations of 24 Gauss number. RESULTS: In the case of the conventional asphalt mixture, similar trends were observed when the relaxation modulus and thermal stress results were compared. In the case of RAP and Shingle added mixtures, relatively different computation results were obtained. It can be estimated that different experimental surroundings and specimen sizes affected the results. CONCLUSIONS: It can be said that the BBR mixture creep test can be a more viable approach for measuring low temperature properties of asphalt mixture compared to expensive and complex IDT testing methods. However, more extensive research and analysis are required to further verify the feasibility of the BBR mixture creep test.

This paper examines a simple one-step and catalyst-free method for synthesizing carbon nanoparticles from aliphatic alcohols and n-hexane with linear molecule formations by using a stable solution plasma process with a bipolar pulse and an external resistor. When the external resistor is adopted, it is observed that the current spikes are dramatically decreased, which induced production of a more stable discharge. Six aliphatic linear alcohols (methanol- hexanol) containing carbon with oxygen sources are studied as possible precursors for the massive production of carbon nanoparticles. Additional study is also carried out with the use of n-hexane containing many carbons without an oxygen source in order to enhance the formation of carbon nanoparticles and to eliminate unwanted oxygen effects. The obtained carbon nanoparticles are characterized with field emission-scanning electron microscopy, energy dispersive X-ray spectroscopy, and Raman spectroscopy. The results show that with increasing carbon ratios in alcohol content, the synthesis rate of carbon nanoparticles is increased, whereas the size of the carbon nanoparticles is decreased. Moreover, the degree of graphitization of the carbon nanoparticles synthesized from 1-hexanol and n-hexane with a high carbon (C)/oxygen (O) ratio and low or no oxygen is observed to be greater than that of the carbon nanoparticles synthesized from the corresponding materials with a low C/O ratio.

Performance-based seismic evaluation is usually done by considering simplified models for the liquid storage tanks therefore, it is important to validate those simplified models before conducting such evaluation. The purpose of this study is to compare the seismic response results of the FSI (fluid-structure interaction) model and the simplified models for the cylindrical liquid storage tanks and to verify the applicability of the simplified models for estimating failure probability. Seismic analyses were carried out for two types of storage tanks with different aspect ratios (H/D) of 0.45 and 0.86. FSI model represents detailed 3D fluid-structure interaction model and simplified models are modeled as cantilever mass-spring model, frame type mass-spring model and shell type mass-spring model, considering impulsive and convective components. Seismic analyses were performed with modal analysis followed by time history analysis. Analysis results from all the models were verified by comparing with the results calculated by the code and literature. The results from simplified models show good agreement with the ones from detailed FSI model and calculated results from code and literature, confirming that all three types of simplified models are very valid for conducting failure probability analysis of the cylindrical liquid storage tanks.

Among the 8,700 in-service bridges in national highway, the steel bridges cover the 1600 sites and make up approximately the 20 percentage of the total amounts. Due to recent rapid increase both in traffic volume and in frequency of overloaded vehicles, the need for re-evaluating the fatigue life of the steel bridges is increasing. However, the existing fatigue life assessment method are too complicate and difficult to apply to field directly. To improve such deficiency of the existing fatigue life assessment procedures, this study reviews the fatigue life assessment methods in Eurocode and then proposes an easier and simpler fatigue life assessment procedure that could evaluate the remaining fatigue life of the steel bridges using traffic data collected from a high-speed weigh-in-motion system installed in the national highway network. The Proposed fatigue life evaluation method is as follows; 1. Calculation of fatigue resistance 𝛾𝑀f and fatigue strength Δ𝜎𝑐 used in design, 2. Calculation of partial safety factor 𝛾𝐹f for equivalent stress range, 3. Calculation of stress range Δ𝜎𝐸2 using influence line, 4. Calculation of damage equivalent factor λ, 5. Review of Fatigue state and evaluation of fatigue life. The Proposed method can omit the existing complicated and repetitive calculation. Therefore, proposed method can estimate the fatigue damage and the theoretical fatigue life simply by comparing with the existing method.

The recent increase in truck traffic volume and overloading frequency causes a growing need to re-evaluation of fatigue life of steel bridges. However, the traditional fatigue analysis method, that is cumulative damage method(CDM), has limitation to apply to a number of bridges because the required calculation steps are very cumbersome and complicated. This study investigates the feasibility and applicability of proposed simple fatigue evaluation method based on the equivalent damage method (EDM) in Eurocode to estimate the remaining fatigue life for a highway bridge. The Proposed fatigue life evaluation method is as follows; 1. Calculation of fatigue resistance 𝛾𝑀f and fatigue strength Δ𝜎𝑐 used in design, 2. Calculation of partial safety factor 𝛾𝐹f for equivalent stress range, 3. Calculation of stress range Δ𝜎𝐸2 using influence line, 4. Calculation of damage equivalent factor λ, 5. Review of Fatigue state and evaluation of fatigue life. The specifications of the target bridge are as follows; Location : Gyeongbu Expressway, Design Life : 100yr, Construction year : 2006, Total length : 341m, Type of superstructure : continuous steel box girder. The resulting remaining fatigue life estimated by both EDM and CDM have been compared. Remaining fatigue life of target bridge in 2016 was calculated 365yr(EDM using WIM data in 2014), 334yr(CDM using strain gauge data in 2012 and reflecting 2% annual traffic volume increase, Gil and Kang(2012)). As a result of comparison, The remaining fatigue life using proposed method(EDM) was evaluated about 10% higher than the CDM. This result, because traffic volume increase had not reflected when calculation of remaining fatigue life using EDM. Proposed method(EDM) can evaluate remaining fatigue life more easily and simply than CDM.

Almost all buildings and infrastructures made of advanced composite materials are fabricated without proper design. Unlike airplanes or automobiles, prototype test is impossible. One cannot destroy 10 story buildings or 100-meter long span bridges. People try to build 100-story buildings or several thousand meter long span bridges. In order to realize "composites in construction", the following subjects must be studied in detail, for his design. Simple method of analysis, Folded plate theory, Size effects in failure, and Critical natural frequency. Unlike the design procedure with conventional materials, his design should include material design, selection of manufacturing methods, and quality control methods, in addition to the fabrication method. In this paper, folded plate theory are presented for practicing engineers.

As buildings are becoming larger, demand for large-scale composite columns for heavy load is increasing. Welded built-up CFT column (ACT Column I) previously developed by authors of this study is structurally stable and economical. Characteristic of welded built-up CFT column is that there is a limitation of cross-sectional size and application of external diaphragm connection to ensure continuity of rib. Then, composite mega column (ACT Column II) was developed to improve limit of cross-sectional size. Composite mega column has a closed cross section like welded built-up CFT column, but thick plate is inserted between cold-formed steel to expand cross section size. However, when external diaphragm connection is applied to composite mega column, amount of steel is increased greatly and interference with finishing material occurs. In this study, internal diaphragm connection is applied through characteristic of composite mega column to which beam flange or stiffener can be attached to plate. In order to analyze this, simple tensile experiment of composite mega column connection with T-shaped stiffener was performed.

Hypsizygus marmoreus is a mushroom with abundant flavor and medicinal properties. However, its application is limited by problems such as long cultivation period, low biological efficiency, and microbiological contamination; therefore, there is a substantial need for development of new cultivars of this species. In this study, 55 strains of H. marmoreus were subjected to inter simple sequence repeat (ISSR) analysis to identify markers for the selection of mother strains for breeding from the collected germplasm. ISSR 13 and 15 were confirmed as polymorphic markers. The three strains (KMCC03106, KMCC03107, and KMCC03108) with white cap color were found to be genetically closely related upon UPGMA analysis of both ISSR 13 and 15. Based on the PCR analysis results for ISSR 15, the collected germplasm were differentiated into three groups according to the strain collection year. Thus, ISSR 15 could be a marker for determining the phylogeny of cap color and genetic variations according to the strain collection year. These results suggest that ISSR markers can be effective tools for the selection of mother strains for breeding of H. marmoreus.

The organic light-emitting diodes are fabricated with six anthracene derivatives containing simple substituents such as phenyl or naphthyl group. The device structure is as in the following: Indium tin oxide (ITO) (180 nm)/4,4-4,4`,4``-tris[N-(1-naphthyl)-Nphenylamino] triphenylamine (2-TNATA) (30 nm)/4,4`-bis[N-(1-naphthyl)-N-phenyl-1-amino] biphenyl (NPB) (20 nm)/Emitting compound (30 nm)/2,2′,2"- (1,3,5-Benzinetriyl)-tris (1-phenyl-1-H–benz-imidazole) TPBi (40 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). In the emitting layer the anthracene derivatives are used without any dopant. All the six devices show blue emissions. Among the tested diodes, the one with 9-(2-naphthyl)-10-(p-tolyl) anthracene (2-NTA) exhibited luminous efficiency, power and external quantum efficiencies of 3.26 cd/A, 0.98 lm/A, 2.8 % at 20 mA/cm .

A. bisporus is the fifth most cultivated mushroom in Korea, and approximately 10,757 tons were cultivated in 2015. The genetic diversity of collected strains in Korea and commercial cultivars was analyzed using inter-simple sequence repeat (ISSR) markers. ISSR markers known to be comparable among A. bisporus spp. were selected from various markers. Totally, 16 markers, namely the ISSR markers 807, 808, 810, 811, 834, 835, 836, 841, 842, P3, P8, P17, P22, P30, P38, and P39, were evaluated to discriminate between ASI 1110, 1114, 1115, 1238, 1246, 1365, 1366, and 1369 for selecting suitable markers in 16 markers. The ISSR markers P31, P38 and P39 exhibited various fingerprints that could help classify the strains in species. Using the three markers, genetic relationships among 39 strains, including commercial cultivars, such as SaeA and SaeYeon, were analyzed using the UPGMA method. The results of the analysis of the genetic relationships between commercial cultivars and collected strains in Korea confirmed that the commercial cultivars were different from the collected strains in Korea. These results suggested that the ISSR markers P31, P38, and P30 could be used for selecting the commercial cultivars of A. bisporus.

The white button mushroom, Agaricus bisporus, is commercially the fifth most important edible mushroom, accounting for the production of 9,732 tons of mushrooms in Korea in 2015. The genus Agaricus has been known for its potential to degrade lignocellulosic materials. Chemical analyses carried out during the cultivation of A. bisporus indicated that the cellulose, hemicellulose, and lignin fractions were changed preferentially for both vegetative growth and sexual reproduction. We screened A. bisporus strains for effective biodegradation through extracellular enzyme activity using cellulase, xylanase, and ligninolytic enzymes. The enzyme biodegradations were conducted as follows: mycelia of collected strains were incubated in 0.5% CMC-MMP (malt-mops-peptone), 0.5 Xylan-MMP, and 0.5% lignin-MMP media for 14 days. Incubated mycelia were stained with 0.2% trypan blue. Eighteen strains were divided into 8 groups based on different extracellular enzyme activity in MMP media. These strains were then incubated in sterilized compost and compost media for 20 days to identify correlations between mycelial growth in compost media and extracellular enzyme activity. In this study, the coefficient of determination was the highest between mycelial growth in compost media and ligninolytic enzyme activity. It is suggested that comparison with ligninolytic enzyme activity of the tested strains is a simple method of screening for rapid mycelial growth in compost to select good mother strains for the breeding of A. bisporus.

This study was conducted to develop a simple volume model for the Larix kaempferi species in the Central Region of South Korea. General volume model forms were used and validated using a subset of the data collected for the L. kaempferi species. A total of 550 trees were collected in the different L. kaempferi stands through destructive sampling. The dataset was randomly divided into two: 80% for initial model development(seven volume models) and 20% for model validation. The 100% dataset was used for the final model fitting. Evaluation statistics including bias(Ē), absolute mean deviation(AMD), root mean square error(RMSE), coefficient of determination(R2), and the Akaike Information Criterion values(AIC) and weight (AICw) were used to assess performance of the different volume models. Rank analysis was employed and the first five best volume models were chosen for the model validation and final model fitting. The evaluations showed that volume model 4(V=aDBHb*Hc) had the best performance, while volume model 3(V=aDBH+bDBH2), which has a single variable, had the poorest performance.