• Analytical Science and Technology
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• v.35 no.1
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• pp.15-23
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• 2022

Food delivery is gaining popularity due to changes in lifestyle and dietary patterns. However, packages used to delivery food may contain contaminants including heavy metals, or additives added during manufacturing process which may migrate into food during processing and transportation. In this study, a total of 58 food packages for delivery were collected and tested for migration of heavy metals (lead, cadmium and arsenic), bisphenol A and phenol into food simulants. The method was validated by evaluating linearity of calibration curve, limit of detection, limit of quantification, recovery and precision. Result of heavy metal migration showed that lead was the most frequently migrated metal and the highest concentration was detected in a polypropylene sample. Although there are no specific migration limits for bisphenol A and phenol in packaging materials tested in this study, migrations of bisphenol A and phenol were detected in some packages. This may due to contamination or additives added during manufacture of packages. Risk (%) was calculated to analyze the risk associated with the migration of heavy metals, bisphenol A and phenol, and was always below 1 %. These results showed that food packages for delivery are safe in terms of heavy metals, bisphenol A and phenol migration.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.11
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• pp.455-464
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• 2022

There are two unique characteristics of the datasets from a manufacturing process. They are the severe class imbalance and lots of Out-of-Distribution samples. Some good strategies such as the oversampling over the minority class, and the down-sampling over the majority class, are well known to handle the class imbalance. In addition, SMOTE has been chosen to address the issue recently. But, Out-of-Distribution samples have been studied just with neural networks. It seems to be hardly shown that Out-of-Distribution detection is applied to the predictive model using conventional machine learning algorithms such as SVM, Random Forest and KNN. It is known that conventional machine learning algorithms are much better than neural networks in prediction performance, because neural networks are vulnerable to over-fitting and requires much bigger dataset than conventional machine learning algorithms does. So, we suggests a new approach to utilize Out-of-Distribution detection based on SVM algorithm. In addition to that, bagging technique will be adopted to improve the precision of the model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.4
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• pp.233-239
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• 2022

The injection molding process is a process in which thermoplastic resin is heated and made into a fluid state, injected under pressure into the cavity of a mold, and then cooled in the mold to produce a product identical to the shape of the cavity of the mold. It is a process that enables mass production and complex shapes, and various factors such as resin temperature, mold temperature, injection speed, and pressure affect product quality. In the data collected at the manufacturing site, there is a lot of data related to good products, but there is little data related to defective products, resulting in serious data imbalance. In order to efficiently solve this data imbalance, undersampling, oversampling, and composite sampling are usally applied. In this study, oversampling techniques such as random oversampling (ROS), minority class oversampling (SMOTE), ADASYN(Adaptive Synthetic Sampling), etc., which amplify data of the minority class by the majority class, and complex sampling using both undersampling and oversampling, are applied. For composite sampling, SMOTE+ENN and SMOTE+Tomek were used. Artificial neural network techniques is used to predict product quality. Especially, MLP and RNN are applied as artificial neural network techniques, and optimization of various parameters for MLP and RNN is required. In this study, we proposed an SA technique that optimizes the choice of the sampling method, the ratio of minority classes for sampling method, the batch size and the number of hidden layer units for parameters of MLP and RNN. The existing sampling methods and the proposed SA method were compared using accuracy, precision, recall, and F1 Score to prove the superiority of the proposed method.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.25-32
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• 2022

Investment casting is a production method commonly used to manufacture precision equipment, medical fields, and accessories, and has continued to develop through the modernization of equipment and high quality of materials, and its scope of use has been expanded. The purpose of this study is to minimize the defect rate by deriving structural improvement and standardization of mold temperature, which are key elements of the investment casting process, to minimize the defect rate. The scope of the study is limited to jewelry manufacturing casting processes suitable for understanding the structure and principles of small gate, and an experimental research is to be conducted by using soft Wax, gypsum powder, and 14 K gold as research materials. According to the results, the most appropriate casting standard temperature for the casting pattern of Alloy 14 k was the lowest turbulence at 980℃ flask temperature of 550℃, so good products could be produced. As a future task of this study, detailed studies are needed to data the structure and system temperature of small gate, reduce production defects in the field, and provide data for excellent investment casting competitiveness.

• Resources Recycling
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• v.32 no.1
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• pp.60-66
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• 2023

As supply chain management becomes a key factor in the sustainable growth of the industry, securing minerals at the national or corporate level is becoming important. Depending on the industrial structure, the economic status of each minerals is different and the supply risk is different In this study, to examine the economic status of minerals, an index that can quantify the Industrial Economic Importance by minerals was developed and calculated by reflecting the demand structure and cost weight of each industry. As a result, Li, Al, Cu, Si, Co, Ni, etc. were evaluated as having high industrial importance in Korea. In addition, by industry, Al, Cu, Zn, and Pb for primary metal manufacturing, general machinery, assembly metals,Sn, Ba, Ti, Si and Ga for precision equipment, Si and Ga for semiconductors, and Li, Ni, Co, Si, etc. for electronic components had high industrial importance. Such as Europe and the United States, in order to select Critical-minerals, Korea will need to analyze the economic impact on the domestic industry as well as the risks of supply chain by minerals.

• Journal of Radiation Protection and Research
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• v.47 no.4
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• pp.214-225
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• 2022

Background: The conventional cerium-doped Gd₂Al₂Ga₃O₁₂ (GAGG(Ce)) scintillator-based gamma-ray imager has a bulky detector, which can lead to incorrect positioning of the gammaray source if the shielding against background radiation is not appropriately designed. In addition, portability is important in complex environments such as inside nuclear power plants, yet existing gamma-ray imager based on a tungsten mask tends to be weighty and therefore difficult to handle. Motivated by the need to develop a system that is not sensitive to background radiation and is portable, we changed the material of the scintillator and the coded aperture. Materials and Methods: The existing GAGG(Ce) was replaced with Bi₄Ge₃O₁₂ (BGO), a scintillator with high gamma-ray detection efficiency but low energy resolution, and replaced the tungsten (W) used in the existing coded aperture with lead (Pb). Each BGO scintillator is pixelated with 144 elements (12 × 12), and each pixel has an area of 4 mm × 4 mm and the scintillator thickness ranges from 5 to 20 mm (5, 10, and 20 mm). A coded aperture consisting of Pb with a thickness of 20 mm was applied to the BGO scintillators of all thicknesses. Results and Discussion: Spectroscopic characterization, imaging performance, and image quality evaluation revealed the 10 mm-thick BGO scintillators enabled the portable gamma-ray imager to deliver optimal performance. Although its performance is slightly inferior to that of existing GAGG(Ce)-based gamma-ray imager, the results confirmed that the manufacturing cost and the system's overall weight can be reduced. Conclusion: Despite the spectral characteristics, imaging system performance, and image quality is slightly lower than that of GAGG(Ce), the results show that BGO scintillators are preferable for gamma-ray imaging systems in terms of cost and ease of deployment, and the proposed design is well worth applying to systems intended for use in areas that do not require high precision.

• The Journal of the Acoustical Society of Korea
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• v.27 no.6
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• pp.271-278
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• 2008

The electro-mechanical characteristics were theoretically analyzed for the wideband ultrasonic transducer made of non-uniform thickness piezoelectric vibrator. This paper proposes a combination of exponential functions which describes the thickness variation along the length of the vibrator to derive the input admittance and power transfer function of the transducer. The bandwidth and the power transfer function of the transducer were investigated while the lateral shape of the vibrator changes. The results showed there is an optimum shape for the wideband characteristics of the transducer, and the bandwidth has increased up to over 100% as the ratio of minimum value of thickness to maximum value decreases. However, the power transfer function had a downward trend as the ratio of thickness decreases. Also we confirmed that even though the value of transfer function increases as the length of the piezoelectric vibrator increases, the shape providing wideband characteristics is very limited. It means that precision processing is required to manufacturing a wideband ultrasonic transducer with high efficiency.

• Journal of the Korean Society of Costume
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• v.22
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• pp.263-276
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• 1994

The achievement of notable social reoforms attained during the period of 19th and 20th centuries needlessly speaking remodelded the social environmental into several different patterns such as :1) high industrialization 2) propensity to consume 3) up graded overall social stands. Accordingly the industrial world of the but-tons too established the mess production syhstem by breaking from convention of hand-craft work of 17th century. The raw materials used in the production line on buttons during the 20th century are almost all-kind of materials one can possibly named including cheap plastic which enabled production lines to produce cheaper but higher productivities of the buttons being produced, The design (incused design) used in the 19-20h centuries are : men landscape, sports features, birds, livestocks, bugs, or geomatric features, tec, 1, The classification o f the buttons by materials Techniques shapes colors marking (Incused design) used in the productionof buttons in the England United States of America Laska Italy france Denmark Japan and India are categolizzed as : natural raw materials and syntetical resines. 1) Of the natural raw materials used are : Matal Enamel Iodine Agate, Coral, Green jade(Jasper) Granite, Wood, Ivory, Horn and bone etc. 2) The sythetical resin used in the button in-dustries are : Artificial jewell glass Acrylic material Styroform Celluloid and Nylon etc. 2. The thecnique quoted in producing buttons are hand craft work inlay work precision casting press mosic dye etching, processing, engraving and embossed carving etc. 3. The major designs used in the buttons in -dustries are : Round shape however elliptical column angular and edge shape often used. 4. The colors used are : The multi-colors were highly used than mono-colored materials such as : Adjoining Color and Contrast Color. The highest consideration to be considered in choosing the colors for the buttons are harmonization and matching factor with the garment or dresses to be wore. 5. The major design(incused design) on the buttons are embodiment and the design were also used in order of abstractive-combination abstractive with has offers much surprising. The button industries during the 19th and 20th centuries were not only the determination factors those can judge the value of self-pride of Nation and which were far beyond the in-dustrial arts in those days but also highly refelected and influenced by cultural sense ideology and self-pride of the Nation of those period. The followings are details of the role of the buttons categolized in the order of functional ornamental and symbolical aspects : 1. The functional role : The functional role of the buttons were simply designed for dress how-ever the buttons beyond from this role of function now a days. 2. The ornamental role : The ornamental role of he button beyond from this role of the button were effectuated by : 1) shape materials colors 2) technique locations size and design (incused design) 3) The ramaterials used for buttons shall not be over looked because it is highly depends on the taste sense and combination of harmony with the garment to be wore. 4) The color of the buttons are made well contrasted with the color of garments just as in the case of other artistical area such as matchs with the color of garment of contrast with brigtness of colors contrasted as complementary color and so and so. 5) The technique being adoped are: precision casting press handcraft inlay work etching mosic etc,. Since the buttons are no longer a simple catching devise used to fasten together the different part of the dress but now it has formed own and occupied the independent role in the garment or dresses location can be de-termined and varying depending on the ideas of designers. The size of the buttons has no specific limits, However the variation has widely dependined on the entire circumperence rhythm contrast harmonization of the garments. 3. The symbolical role : Since the button is no longer a just a simple devise for catching and fastening device used fastening together the different part of the garments but now were built a independent area as major part of the Garment and well reflected all kinds of occupations political background cultural as-pect etc. on the buttons. The design of buttons in the western circles are more simplified but they are polished looks and their techniques of manufacturing are comination of both machanis and handcraft. The colors used in the buttons are pretty well harmonized with garment(dress). Almost all kind of materials can be used in the but-tons however materials used in the buttons are : Bone of livestocks ivory, turtle shell are no longer used because the prevention of cruely of animal. On the contraly the level of buttons indus-try of Korea is far to reach and catch up with the level of western circles. It is highly suggested therefore the but-tons industrial field of Republic of Korea shall place and encouragement in producing beter industrial environment of the buttons based on the traditional and cultural aspect of republic of Korea to produce both manufacturing of qulified and best designed and colored buttons.

• Journal of Practical Engineering Education
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• v.15 no.1
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• pp.119-126
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• 2023

Today, in order to improve fuel efficiency and dynamic behavior of automobiles, an era of light weight and simplification of automobile parts is being formed. In order to simplify and design and manufacture the shape of the product, various components are integrated. For example, in order to commercialize three products into one product, product processing is occurring to a very narrow area. In the case of existing parts, precision die casting or casting production is used for processing convenience, and the multi-piece method requires a lot of processes and reduces the precision and strength of the parts. It is very advantageous to manufacture integrally to simplify the processing air and secure the strength of the parts, but if a deep and narrow pocket part needs to be processed, it cannot be processed with the equipment's own spindle. To solve a problem, research on cutting processing is being actively conducted, and multi-axis composite processing technology not only solves this problem. It has many advantages, such as being able to cut into composite shapes that have been difficult to flexibly cut through various processes with one machine tool so far. However, the reality is that expensive equipment increases manufacturing costs and lacks engineers who can operate the machine. In the five-axis cutting processing machine, when producing products with deep and narrow sections, the cycle time increases in product production due to the indirectness of tools, and many problems occur in processing. Therefore, dedicated machine tools and multi-axis composite machines should be used. Alternatively, an angle spindle may be used as a special tool capable of multi-axis composite machining of five or more axes in a three-axis machining center. Various and continuous studies are needed in areas such as processing vibration absorption, low heat generation and operational stability, excellent dimensional stability, and strength securing by using the angle spindle.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.85-99
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• 2020

Reservoir is an important infrastructure of our society because it can store immense amount of water for various usages - manufacturing, agriculture, drinking, power generation, tourism etc. For maintenance of reservoir, various efforts in administrative and technological aspects are periodically conducted and monitoring the conditions of reservoir bed is the first priority for maintenance of reservoir. To check the conditions of reservoir bed, we measured depth of reservoir by using echo sounder, which is relatively reliable, prior to discharging of stored water and surveyed topography of reservoir by using UAV after discharging of water. Then, we conducted interpolation of measured depth of water by means of inverse distance weighting interpolation, Kriging interpolation, minimum curvature interpolation and radial basis function interpolation and calculated the volume of reservoir for each interpolation method. We compared the calculated volume of reservoir with the volume of water calculated by UAV after discharging of water and found the following results: First, as results of the above processes, we found that the Kriging interpolation was 97% correct in measurement of the volume of reservoir. Second, as results of comparison of differences between topographical areas and interpolated areas after selection of cross section for comparison, Kriging interpolation was found to have the most similar configuration with the topographical configuration by showing the least difference in the area of cross section. Therefore, it is determined that the optimal modeling of reservoir bed with the water depth data measured by echo sounder shall provide basic information for efficient maintenance of reservoir.