• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.219-224
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• 2011

In this study, a piezoelectric smart sensor that can be embedded inside of concrete structures is developed to investigate the early stage of concrete curing. A waterproof coating is used to protect the piezoelectric sensor from moistures of concrete mixture. Also, a mortar case is utilized to encapsulate the sensor to protect it from impact loads. To estimate the strength of concrete, a self-sense guided-wave actuated sensing technique is applied. In the guided wave, its velocity is varied according to the mechanical properties of concrete such as modulus of elasticity. Because modulus of elasticity directly affects the strength of concrete, the guidedwave's velocity also affects the concrete strength development. To verify the feasibility of using the proposed approach, the smart sensor was embedded into a 100MPa concrete cylinder and the self-sense guided wave is continuously measured throughout the curing process. The measurements showed that the propagation time (TOF) of the measured guided waves gradually decreased as the curing age increased. Especially, at the early age of the curing process, the variation of the TOF was very significant. Furthermore, the results showed that there is a linear relationship between the TOF of the self-sense guided waves and the strength of concrete existed. It is safe to conclude that the proposed approach can be used very effectively in monitoring of the strength development of high strength concrete structures.

• Journal of Korean Society of Forest Science
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• v.76 no.2
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• pp.119-126
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• 1987

This study was carried out to elucidate the desirable PEG molecular weight and it's blending methods which can promote the dimensional stabilization of Corpus controversa, Quercus variabilis and Prunus sargentii. The results may be summarized as follows: 1. PEG polymer loading in woods was affected by specific gravity of wood. And the PEG polymer loading was satisfactory except in Quercus variabilis, which shows the blending method of PEG V was proper. 2. Bulking coefficiency of PEG V was high in Corpus controversa and Prunus sargentii, and it is necessary to paint or coat water-proofing wood preservative: for high bulking coefficiency of Quercus variabilis. 3. In the treatment of PEG V, the antishrink efficiency of Prunus sargentii was 82.59% and that of Quercus variabilis 62.79%. 4. Dimensional stabilization of hardwoods did not have apparant relation with PEG blending method. 5. Judging from results, PEG-400 and PEG-1000 would be enough for dimensional stabilization of hardwood having high specific gravity if other factors are considered well.

• Journal of the Society of Disaster Information
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• v.16 no.3
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• pp.602-610
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• 2020

Purpose: This paper aims to develop an asphalt pavement system with reduced cracks, structural stability and waterproofing at sub-zero temperature conditions. Method: Under various temperature conditions, SIS polymer asphalt, normal asphalt, and guss asphalt were tested for adhesion strength of the binder and deformation strength of the mixture. Result: The adhesion strength of asphalt binder was higher in SIS polymer asphalt than that of normal asphalt and guss asphalt. The deformation strength of the asphalt mixture was almost the same as that of SIS polymer asphalt and normal asphalt. The energy absorption of the SIS polymer asphalt mixture was relatively higher than that of the normal asphalt mixture and the guss asphalt mixture. Conclusion: The maximum load of the SIS polymer asphalt mixture was lower than that of the guss asphalt mixture. However, in sub-zero temperature conditions, sufficient energy absorption was secured by stable load reduction. Therefore, it is expected to improve the durability of asphalt pavement by reducing the occurrence of microcracks with stable fracture behavior.

• Korean Journal of Remote Sensing
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• v.27 no.1
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• pp.59-68
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• 2011

The analysis of optimal infiltration path is one of the representative fields in which the GIS technology can be useful for the military purpose. Usually the analysis of the optimal path is done with network data. However, for military purpose, it often needs to be done with raster data. Because raster data needs far more computation than network data, it is difficult to apply the methods usually used in network data, such as Dijkstra algorithm. The genetic algorithm, which has shown great outcomes in optimization problems, was applied. It was used to minimize the detection probability of infiltration route. 2D binary array genes and its crossover and mutation were suggested to solve this problem with raster data. 30 tests were performed for each population size, 500, 1000, 2000, and 3000. With each generation, more adoptable routes survived and made their children routes. Results indicate that as the generations increased, average detection probability decreased and the routes converged to the optimal path. Also, as the population size increases, more optimal routes were found. The suggested genetic algorithm successfully finds the optimal infiltration route, and it shows better performance with larger population.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.35-44
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• 2018

The purpose of this study was to derive the factors that affect the development cost and the priority/weight of effectiveness in the pre-development stage of a service robot to estimate the development cost. In particular, the functions of service robots vary according to the field of application, and their prices are not only different but most of them are small-scale production; hence, a cost estimation is necessary. In this research, the factors affecting the service robot development cost in the process of service robot development and adding functions are classified as a functional factor while the factors that affect the entire development cost due to environmental causes, in which the service robot is operated or in the development process, are classified as an adjustment factor. The FGI was conducted to derive the factors and a Delphi survey was conducted among 84 domestic experts to determine the weights of the factors. As a result of the analysis, six functional factors (41 detailed criteria) and five adjustment factors (17 criteria) were derived, the cost weight and rank of the factors were suggested. This study suggests that the development cost of the service robot can be used as a decision-making strategy to select the operation functions in the development process, and can be utilized as an essential tool for the service robot development.

• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.433-440
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• 2005

Four varieties of perilla(Perilla ocimoids L.) were tested to investigate the ecological adaptation of the crop to variations in sowing time extending from April 25 to July 25 with an interval of 30 days between each of the four sowing. As sowing time was delayed, the plant height, the number of first branches and cluster, the weight of fresh and dried stems, the day to germination and flowering decreased, showing a highly negative correlation between the showing dates and these characteristics, but a highly positive correlation between days to flowering and the required accumulated temperature. With early sowing under low temperature and long day conditions, it took about 132 days from sowing to flowering due to the long period of vegetative growth, but as sowing was delayed, the days to flowering decreased with a minimum period of 57 days. The yield of seeds in each case varied with each variety. Type A(Nonsan var.) and type B(Jinchon var.) had higher yields when sowed earlier. But type C(Namyang var. and Wooljin var.) had its highest yield in the plot sowed on May 25 and the 1000 grain weight showed a tendency to increase as sowing was delayed. In conclusion, the perilla was preyed to be a short-day plant that flowers from the begining to the middle of Sep. regardless of sowing time, so that the sowing time should be decided after due consideration of the length of the vegetative growth periods of the varieties.

• Radiation Oncology Journal
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• v.7 no.1
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• pp.85-92
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• 1989

Dosimerty based on electron spin resonance (ESR) analysis of radiation induced free radicals in amino acids is relevant to biological dosimetry applications. Alanine detectors are without walls and are tissue equivalent. Therefore, alanine ESR dosimetry looks promising for use in the therapy level. The dose range of the alanine/ESR dosimetry system can be extended down to 1 Gy. In water phantom the absorbed dose of electrons generated by a medical linear accelerator of different initial energies $(6\~21MeV)$ and therapeutic dose levels (1~60 Gy) was measured. Furthermore, depth dose measurements carried out with alanine dosimeters were compared with ionization chamber measurements. As the results, the measured absorbed doses for shallow depth of initial electron energies above 15 MeV were higher by$2\~5\%$ than those calculated by nominal energy $C_E$ factors. This seems to be caused by low energy scattered beams generated from the scattering foil and electron cones of beam projecting device in medical linear accelerator.

• Journal of the Korean Geosynthetics Society
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• v.10 no.4
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• pp.71-79
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• 2011

In this study, the variation of wetting front and ground water level at the embankment constructed in the Saemangeum area were predicted considering rainfall duration times and the slope stability analysis of the embankment was carried out according to prediction results of wetting front and ground water level. The embankment was formed by dredging soils. A suction stress, a cohesion and a frictional angle of dreding soils measured by soil tests were applied to estimate the unsaturated soil properties. According to the analysis results of the wetting front and the ground water level for various rainfall duration time, the wetting front began to descend from the upper part of embankment at the beginning time of rainfall and after 1 hour of rainfall duration time. After that, the ground water level continued to ascend as the rainfall duration time was getting longer. After rainfall, the ground water level was distributed at a certain depth, and the ground water level was gradually descending as time goes by. According to the slope stability analysis of the embankment considering the variation of the wetting front and the ground water level, the safety factor of slope was rapidly reduced as the rainfall began to infiltrate into the ground, and the minimum safety factor of slope was estimated after 24 hours of rainfall duration time. Meanwhile, the safety factor of slope was increased with regaining the matric suction in the ground after rainfall.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.134-152
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• 2020

Objectives: The objective of this study was to evaluate volatile organic compounds (VOCs) and toluene diisocyanates (TDIs) exposure among polyurethane waterproofing workers in the construction industry. Methods: Task-based personal air samplings were carried out at seven construction sites using organic vapor monitor for VOCs (n=88) and glass fiber filters coated with 1-(2-pyridyl)piperazine(1-2PP) for TDIs (n=81). The concentration of VOCs and TDIs were shown for four different work types(mixing paint, primer roller painting, urethane resin spread painting, painter assistant) at five different worksites (rooftop, ground parking lot, piloti, bathroom, and swimming pool). The two TDI sampling methods (filter vs impinger) were evaluated in parallel to compare the concentrations. Results: The geometric mean(GM) concentration of VOCs Exposure Index (EI) was highest for primer roller painting (1.4), followed in order by, urethane resin spread painting (0.85), mixing paint (0.53), and painter assistant (0.35) by work types. The GM of VOCs EI was highest for bathroom (1.4) followed in order by, swimming pool (0.85), piloti (0.89), ground parking lot (0.82) and rooftop (0.57) by worksites. The GM of 2,4-/2,6-TDI concentration was 0.052 ppb and 0.432 ppb each. There was no statistical difference in TDIs concentrations among worksites. The concentration of 2,6-TDI was ten times higher than that of 2,4-TDI. The concentration of 2,6-TDI by impinger method was 5.7 times higher than that by filter method. Conclusions: In this study, we found 38.6% of the VOCs samples exceeded the occupational exposure limits and 19.8% of the 2,6-TDI samples exceeded 1 ppb among polyurethane waterproofing workers. The most important determinants that increase the concentration of VOCs and TDIs was indoor environment and primer painting work.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.5
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• pp.440-448
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• 1990

To obtain the basic information an seed quality improvement in sesame, protein content of 114 varieties and amino acid composition of 12 varieties was analyzed. Protein content showed the vaietal difference ranged 20.6-30.2% and the mean was 24.72%. The highest variety in protein content was PI158066 (30.2%) originated from U.S.A. Protein content of Korean local varieties were highest among original group analyzed. Seed coat texture and seed coat color affected to protein content so, smooth type was higher than rough type in protein content, and black seeded varieties showed the hight protein content. Amino-acid composition of sesame was uneque in balance and higher than FAO reference. Total amino-acid of variety PI258372 was highest as 25.03%. Essential amino-acid (EAA) /total amino-acid(TAA) ratio of sesame was higher as 42-58.2% than soybean, corn, rice, peanut. Korean local variet 'Samcheck' showed best quality in amino-acid composition as 58.2% in EAA/TAA ratio with high tyrocin and lysine. Total amino acid content was high in order of Korean local '||'&'||'gt; introduced '||'&'||'gt; Korean bred varieties.