• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.67-76
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• 2024

In this paper, we present a DIP-MLS testing method that combines digital image processing with a rigid body-based MLS differencing approach to measure mechanical variables and analyze the impact of target location and image resolution. This method assesses the displacement of the target attached to the sample through digital image processing and allocates this displacement to the node displacement of the MLS differencing method, which solely employs nodes to calculate mechanical variables such as stress and strain of the studied object. We propose an effective method to measure the displacement of the target's center of gravity using digital image processing. The calculation of mechanical variables through the MLS differencing method, incorporating image-based target displacement, facilitates easy computation of mechanical variables at arbitrary positions without constraints from meshes or grids. This is achieved by acquiring the accurate displacement history of the test specimen and utilizing the displacement of tracking points with low rigidity. The developed testing method was validated by comparing the measurement results of the sensor with those of the DIP-MLS testing method in a three-point bending test of a rubber beam. Additionally, numerical analysis results simulated only by the MLS differencing method were compared, confirming that the developed method accurately reproduces the actual test and shows good agreement with numerical analysis results before significant deformation. Furthermore, we analyzed the effects of boundary points by applying 46 tracking points, including corner points, to the DIP-MLS testing method. This was compared with using only the internal points of the target, determining the optimal image resolution for this testing method. Through this, we demonstrated that the developed method efficiently addresses the limitations of direct experiments or existing mesh-based simulations. It also suggests that digitalization of the experimental-simulation process is achievable to a considerable extent.

• Journal of Intelligence and Information Systems
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• v.23 no.1
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• pp.47-67
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• 2017

Steel plate faults is one of important factors to affect the quality and price of the steel plates. So far many steelmakers generally have used visual inspection method that could be based on an inspector's intuition or experience. Specifically, the inspector checks the steel plate faults by looking the surface of the steel plates. However, the accuracy of this method is critically low that it can cause errors above 30% in judgment. Therefore, accurate steel plate faults diagnosis system has been continuously required in the industry. In order to meet the needs, this study proposed a new steel plate faults diagnosis system using Simultaneous MTS (S-MTS), which is an advanced Mahalanobis Taguchi System (MTS) algorithm, to classify various surface defects of the steel plates. MTS has generally been used to solve binary classification problems in various fields, but MTS was not used for multiclass classification due to its low accuracy. The reason is that only one mahalanobis space is established in the MTS. In contrast, S-MTS is suitable for multi-class classification. That is, S-MTS establishes individual mahalanobis space for each class. 'Simultaneous' implies comparing mahalanobis distances at the same time. The proposed steel plate faults diagnosis system was developed in four main stages. In the first stage, after various reference groups and related variables are defined, data of the steel plate faults is collected and used to establish the individual mahalanobis space per the reference groups and construct the full measurement scale. In the second stage, the mahalanobis distances of test groups is calculated based on the established mahalanobis spaces of the reference groups. Then, appropriateness of the spaces is verified by examining the separability of the mahalanobis diatances. In the third stage, orthogonal arrays and Signal-to-Noise (SN) ratio of dynamic type are applied for variable optimization. Also, Overall SN ratio gain is derived from the SN ratio and SN ratio gain. If the derived overall SN ratio gain is negative, it means that the variable should be removed. However, the variable with the positive gain may be considered as worth keeping. Finally, in the fourth stage, the measurement scale that is composed of selected useful variables is reconstructed. Next, an experimental test should be implemented to verify the ability of multi-class classification and thus the accuracy of the classification is acquired. If the accuracy is acceptable, this diagnosis system can be used for future applications. Also, this study compared the accuracy of the proposed steel plate faults diagnosis system with that of other popular classification algorithms including Decision Tree, Multi Perception Neural Network (MLPNN), Logistic Regression (LR), Support Vector Machine (SVM), Tree Bagger Random Forest, Grid Search (GS), Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The steel plates faults dataset used in the study is taken from the University of California at Irvine (UCI) machine learning repository. As a result, the proposed steel plate faults diagnosis system based on S-MTS shows 90.79% of classification accuracy. The accuracy of the proposed diagnosis system is 6-27% higher than MLPNN, LR, GS, GA and PSO. Based on the fact that the accuracy of commercial systems is only about 75-80%, it means that the proposed system has enough classification performance to be applied in the industry. In addition, the proposed system can reduce the number of measurement sensors that are installed in the fields because of variable optimization process. These results show that the proposed system not only can have a good ability on the steel plate faults diagnosis but also reduce operation and maintenance cost. For our future work, it will be applied in the fields to validate actual effectiveness of the proposed system and plan to improve the accuracy based on the results.

• Journal of the Korean GEO-environmental Society
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• v.18 no.10
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• pp.23-34
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• 2017

As the electrical property of fully saturated soils is dependent on the pore water, it has been commonly used for the detection of the contamination into the ground. The objective of this study is to investigate the electrical characteristics according to the salinity and the lead concentration in fully saturated soils. Fresh water and saline water with the salinity of 1%, 2% and 3%, which are mixed with 6 different lead solutions with the range of 0~10 mg/L, are prepared in the cylindrical cell incorporated with sensors for measuring electrical resistance and time domain reflectometry signal. Then, the dried sands are water-pluviated into the cell. The electrical resistance and the time domain reflectometry signal are used to estimate the electrical conductivity. Test results show that electrical conductivity determined from electrical resistance at the frequency of 1 kHz continuously increases with an increase in the lead concentration, thus it may be used for the estimation of the contaminant level. In addition, the electrical conductivity estimated by the time domain reflectometry changes even at very low concentration of lead, the variation rate decreases as the lead concentration increases. Thus, the time domain reflectometry can be used for the investigation of the heavy metal leakage. This study demonstrates that complementary characteristics of electrical resistance and time domain reflectometry may be used for the detection of the leakage and contamination of heavy metal in coastal and marine environments.

• Economic and Environmental Geology
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• v.39 no.3 s.178
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• pp.269-284
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• 2006

Aquifer responses to the river stage fluctuations were analyzed between the groundwater level and the river stage in an alluvial aquifer. The auto-correlation and cross-correlation as a time series analysis were applied. Study site is a floodplain in the Mangyeong river. Groundwater levels in each depth representing the silt and sand(SS), gravel and sand(GS), and weathered zone(WZ) layer were monitored. The groundwater levels were more sensitive to the river stage fluctuations than rainfall. Since the river stages are influenced by the gate operations downstream and tide, show periodic patterns, and the correlation coefficients with rainfall is low. Cross-correlation function between groundwater level in each depth do not show any delay time, then response time is very short to each depth. Cross-correlation analysis were performed to estimate the response time of groundwater levels to river stage fluctuations. Groundwater levels respond to the river stage within 30 minutes to 1 hour in wells near the stream. Short time lag between groundwater level and river stage indicates the quick response. A different response time imply the hydraulic inhomogeneity of the site, and a probable high permeability zone between river and aquifer can be inferred. Mangyeong-river in study site is a gaining stream normally, and river stage rising by gate operation or floods makes river water flow into groundwater. The auto-correlation and cross-correlation functions as a time series analysis can be a good tool to interpret the aquifer responses to stream stage fluctuation

• Journal of Animal Science and Technology
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• v.49 no.1
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• pp.89-98
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• 2007

This study was carried out to compare the quality characteristics including aroma compounds and pattern of M. Biceps femoris from Korean native black pigs (70kg, 6 months, KNP) and modern genotype pigs (103kg, 6 months, Landrace×Yorkshire, MGP) during vacuum-storage at 2±0.2℃ for 12 days. KNP had high contents of crude protein and ash, but low content of moisture as compared to MGP (p<0.05). KNP showed lower pH and higher cooking loss than MGP (p<0.05) during storage. CIE a* and b* values of KNP significantly higher during storage as compared to those of MGP (p<0.05). TBARS value of KNP significantly increased after 8 days as compared to that of MGP (p<0.05). Shear force value of KNP was higher than that of MGP until 8 days (p<0.05). Volatiles by SPME-GS/MS was slightly different between KNP and MGP, but aroma pattern by electronic nose was not different. Therefore, KNP had redder and darker color, higher cooking loss and harder texture than MGP. The sensory quality of KNP was better than those of MGP (p<0.05), although aroma characteristics by instruments were not different between KNP and MGP.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.9
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• pp.476-481
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• 2016

Pressure retarded osmosis (PRO) is a quite new technique for power generation using an osmotically driven membrane process. In the PRO process, water permeates through a semipermeable membrane from a low concentration feed solution to a high concentration draw solution due to osmotic pressure. This study carried out to evaluate the performance of the 8 in spiral wound membrane module using reverse osmosis concentrate for a draw solution and reverse osmosis permeate for a feed solution. Three different flowrates of draw and feed solution, such as 2.4 L/min, 5.0 L/min, and 10.0 L/min were used to estimate the power density and water flux under various range of hydraulic pressure differences between 5 bar and 30 bar. In addition, the effects of feed and draw solution concentration, flowrate, and mixing ratio on 8 in spiral wound PRO membrane module performance were investigated in this study. As major results, increases of the draw solution concentration lead to the improvement of power denstiy, and water flux. Also, increase of flowrate resulted in the improvement of power density and water flux. In addition, optimal mixing ratio of draw and feed solution inlet flowrate was found to be 1:1 to attain a maximum power denstiy.

• Korean Journal of Microbiology
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• v.24 no.4
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• pp.352-356
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• 1986

A study was carried out to determine the effect of ginseng saponin an its related materials on aflatoxin production by Aspergillus parasiticus NRRL2999 in glucose-salts(GS) medium. Maximal growth of the mold and AF froduction in the medium occurred after 5 and 9 days at $28^{\circ}C$, respectively. When various concentrations of saponin added to the medium aflatoxin synthesis were significantly reduced (p<0.05) compared to the control after 9 days at $28^{\circ}C$. 0.05% of saponin inhibited aflatoxin production most effectively in the low concerntrations of saponin (0.01-0.2%) and the toxin synthesis reduced with an increasing concentrations of saponin in the high concentrations (0.03-5.0%). Various concentrations (0.01-1.0%) of saponin diol and triol in the media also caused to reduce aflatoxin synthesis by the mold (p<0.05). All saponin fractions were found to decrease aflatoxin production significantly. Saponin fraction numbers of 1,2,4 and 6 were shown to reduce aflatoxin production effectively, and the number 1 was the most effective. Addition of 0.05% of nucleic acid related materials to the medium reduced aflatoxin production (p<0.05). Aflatoxins could not be found in broth at all, but in mycelia when 0.05% of caffeine was added to the medium. Aflatoxin synthesis was well correlated with total lipid synthesis, growth and glucose uptake. When aflatoxin synthesis inhibited (5.0% of saponin) both total lipid synthesis and growth were stimulated and the efficiency of glucose utilization was reduced.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.369-375
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• 2014

This study examined the changes of microstructural compositions in cement matrix according to the depth from the surface of a reinforced concrete (RC) column exposed to fire. The RC column was exposed to a standard fire for 180 minutes. After the fire test, core samples passing through the column section were obtained. Using the core samples, the remaining fractions of calcium-silicate-hydrates (C-S-H) and calcium hydroxide in cement matrix at the surface, the depth of 40 mm and 80 mm and the center (175 mm) were examined using thermal gravimetric analysis (TGA) and X-ray diffraction analysis (XRDA). Using nuclear magnetic resonance (NMR) technique, the silicate polymerization of C-S-H in cement matrix was also evaluated. The experimental results indicated that the amount of C-S-H loss at the center of column experiencing the transferred fire temperature of $236^{\circ}C$ has been underestimated as the TGA results showed the highest C-S-H contents are located at the depth of 80 mm, where the transferred fire temperature is $419^{\circ}C$. Moreover, the destruction of silicate connections at the center was observed as similar as that at the depth of 40 mm, where the transferred fire temperature was $618^{\circ}C$. This might be attributed to the temperature changes during cooling time after the fire test was neglected. Due to the relatively low thermal conductivity of concrete, the high temperature, which can affect the change of microstructure in cements, will hold longer at the center of the column than other depth.

• Macromolecular Research
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• v.11 no.4
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• pp.207-223
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• 2003

For last five years, we are developing the novel local drug delivery devices using biodegradable polymers, especially polylactide (PLA) and poly(D,L-lactide-co-glycolide) (PLGA) due to its relatively good biocompatibility, easily controlled biodegradability, good processability and only FDA approved synthetic degradable polymers. The relationship between various kinds of drug [water soluble small molecule drugs: gentamicin sulfate (GS), fentanyl citrate (FC), BCNU, azidothymidine (AZT), pamidronate (ADP), $1,25(OH)_2$ vitamin $D_3$, water insoluble small molecule drugs: fentanyl, ipriflavone (IP) and nifedipine, and water soluble large peptide molecule drug: nerve growth factor (NGF), and Japanese encephalitis virus (JEV)], different types of geometrical devices [microspheres (MSs), microcapsule, nanoparticle, wafers, pellet, beads, multiple-layered beads, implants, fiber, scaffolds, and films], and pharmacological activity are proposed and discussed for the application of pharmaceutics and tissue engineering. Also, local drug delivery devices proposed in this work are introduced in view of preparation method, drug release behavior, biocompatibility, pharmacological effect, and animal studies. In conclusion, we can control the drug release profiles varying with the preparation, formulation and geometrical parameters. Moreover, any types of drug were successfully applicable to achieve linear sustained release from short period ($1{\sim}3$ days) to long period (over 2 months). It is very important to design a suitable formulation for the wanting period of bioactive molecules loaded in biodegradable polymers for the local delivery of drug. The drug release is affected by many factors such as hydrophilicity of drug, electric charge of drug, drug loading amount, polymer molecular weight, the monomer composition, the size of implants, the applied fabrication techniques, and so on. It is well known that the commercialization of new drug needs a lot of cost of money (average: over 10 million US dollar per one drug) and time (average: above 9 years) whereas the development of DDS and high effective generic drug might be need relatively low investment with a short time period. Also, one core technology of DDS can be applicable to many drugs for the market needs. From these reasons, the DDS research on potent generic drugs might be suitable for less risk and high return.

• The Journal of Industrial Distribution & Business
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• v.1 no.1
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• pp.5-12
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• 2010

The retail business of drugstore was introduced to Korea for the first time 10 years ago. Since Olive Young introduced a retail store in the name of drugstore in 1999 for the first time in Korea, new distribution channel combining drugstore, cosmetic products and dairy products, etc has been made. At initial stage, the new distribution channel grew up slowly because of low specialty and economic stagnation. However, the three big distribution channels, that is to say, Olive Young (CJ), Watsons (GS) and W Store (Kolon Well Care), etc, were established to produce new distribution system following large-scaled discount stores as well as convenience stores. The purpose of the study is to investigate ways making Korean style drugstore be new retail business in addition to traditional markets, department stores, E-Mart and other general super markets and to examine problems preventing the drugstore from being promoted and to find out solutions. The speciality retailers that is called a category killer attacking department stores as well as marts is expanding market quickly. New consumption trend that gives priority to wellbeing is being expanded in accordance with high level of standards of living life: The drugstore is thought to be new alternative of distribution because it keeps special products. Young ladies who are main customers of drugstores respond to the trend sensitively to have more buying power that is thought to be promising. And, consumers' desire has become concrete and special. This is because consumers want not only convenient shopping but also special shopping system that is current trend. These days, so called Multi-shop and Total shop and other special shops have been recently opened. Special multi-shop has been concentrated on fashion product and miscellaneous goods so far: Health total wellbeing shop shall be popular in accordance with wellbeing trends. Drugstores can play an important role. Drugstores were opened for the first time ten years ago. In particular, Olive Young succeeded in going into the black after making efforts for a long time by many persons. Drugstores could succeed in the business owing to many persons in the past as well as customers who liked drugstores. However, drugstores once lost ways and recorded poor business results. The three drugstores, that is to say, Olive Young, Watsons making efforts to go into the black and W-Store pursuing traditional drugstore shall compete each other and make effort to satisfy customers' desire. In that way, the three drugstores can be assured of present business as well as future business. The consumers' demand trend has become special at sub-division so that drugstores that can satisfy the demand can succeed in the business. Large businesses may be more interested in the 4th generation retail business to produce good income and to have bright future. Drugstore business and market are likely to expand and develop owing to large business' participation in drugstore business. Drugstores expanded shop at Seoul and Gyeonggi-do until middle of 2000. Drugstore business at station sphere in Seoul and Gyeonggi-do that have high ratio of temporary population has low customer loyalty to have limitation on continuous growth. Since 2009, drugstores have opened new shops at local towns: From the year of 2010, drugstores need to establish multiple shop strategy by accelerating business speed and to allow customers to drop in the shop anywhere in the nation and to enter consumers' life deeply, so that they can strengthen business base definitely. Drugstores need to have price competitiveness to have multiple shop opening strategy and to satisfy consumers and to supply high quality services that is future subject to solve. And, Olive Young and Watsons that are Korean style drugstore need to keep system in order and to strengthen substance as Korean style drugstore and to expand marketing, so that they can get business outcome within 5 years that was done 10 years before and they become the 4th generation retail business. The study had difficulties at collecting material from the three drugstore because of poor cooperation. And, the author had great difficulty at collecting statistical material that was made in disorder. Further effort is needed considering such problems.