• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.19-26
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• 2021

The lattice structure is attracting attention from industry because of its excellent strength and stiffness, ultra-lightweight, and energy absorption capability. Despite these advantages, widespread commercialization is limited by the difficult manufacturing processes for complex shapes. Additive manufacturing is attracting attention as an optimal technology for manufacturing lattice structures as a technology capable of fabricating complex geometric shapes. In this study, a unit cell was formed using a three-dimensional coordinate method. The relative density relational equation according to the boundary box size and strut radius of the unit cell was derived. Simple cubic (SC), body-centered cubic (BCC), and face-centered cubic (FCC) with a controlled relative density were designed using modeling software. The accuracy of the equations for calculating the relative density proposed in this study secured 98.3%, 98.6%, and 96.2% reliability in SC, BCC, and FCC, respectively. A simulation of the lattice structure revealed an increase in compressive yield load with increasing relative density under the same cell arrangement condition. The compressive yield load decreased in the order of SC, BCC, and FCC under the same arrangement conditions. Finally, structural optimization for the compressive load of a 20 mm × 20 mm × 20 mm structure was possible by configuring the SC unit cells in a 3 × 3 × 3 array.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.321-331
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• 2021

This study sought to analyze factors influencing high-risk drinking in single-person households. For this, data from the 2018 community health survey were used. Subjects were 32,389 adults above the age of 19 in single-person households. For the data analysis, high-risk drinking groups were extracted according to the high-risk drinking rate index of the survey to arrive at influencing factors and differences in health-related and sociodemographic characteristics. The IBM SPSS 25.0 software was used for analysis and a complex sampling design was applied. The results showed that the high-risk drinking rate of Korea's single-person households was 15.0% (male: 25.8%, female: 5.8%) and age, education under high school level, service-industry employees, smokers, people with depression, high blood pressure, and irregular breakfast eaters appeared as common elements for both genders. Stress appeared to only affect males while being diabetic only affected females. High-risk drinking was higher for males in their 30~40s and women in their 20~30s. The younger generation showed the highest numbers in high-risk drinking and factors like stress or depression appeared to be influencing factors for high-risk drinking. Hence, mental health programs along with customized health policies through health forms and lifestyle changes will be required to lower the high-risk drinking rates of single-person households.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.524-533
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• 2021

Recently, due to the increasing necessity of developing core parts for weapons systems, the project for localization of parts for weapons systems is expanding. In order to apply the developed core parts to the domestic weapon system and advance into the overseas market, it is necessary to plan a project that reflects the technology trends in advance. This study derived trend of technology development through conducting the patent research and analysis. Also, suggested plan for applying the analysis results when project planning and selecting. As a detailed method, patents related to the 2019 year selection project were investigated. The number of patent applications by year and number of applicants from the time of the first application to the present were analyzed. And the growth stage of the technology market was derived. The comprehensive result was derieved through the portfolio analysis by arranging the parts localization technology in each area of the matrix consisting of market growth stage and the criteria for the selection of parts localization project. This research suggested the applying plan for improving project selection process. we expect the promotion of defense industry and the effective task planning.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.267-272
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• 2021

In this study, the output results of 3D printed exterior materials for application to buildings of various shapes are output tests using test specimens, in which 3D printing concrete is cast in a mold and accelerating agents are used to ensure stackability. The unit weight and strength characteristics of the body were analyzed. Compared to the unit weight of concrete placed in the mold, the unit weight of 3D printing concrete using accelerating agents tends to decrease by approximately 3.5% to 5.0%, and the compressive strength is the compressive strength of the concrete placed in the mold. In comparison, the compression strength of the output by 3D printing tended to decrease by approximately 36% to 46%. In the flexural strength, the compressive strength of the output through 3D printing decreased by approximately 36% to 46% compared to the compressive strength of concrete placed in the mold. The impact on the strength characteristics of 3D printed concrete using accelerating agents tended to decrease by approximately 2.0 to 5.8%. Therefore, 3D printing output accelerating agents can be used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.248-258
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• 2021

The study analyzed the financial determinants of corporate R&D intensity that require more attention from academics and practitioners in the Korean capital market. Domestic small and medium enterprises (SMEs) may face with developing substitutes by making more R&D investments in scale and scope, given the unprecedented economic conditions such as the limitation of importing core components and materials from other nation(s). KOSDAQ-listed SMEs were selected as sample data, whose R&D expenditures may be less than those of large firms during the post-global financial turmoil period (2010~2018). Static panel data model was applied, along with Tobit and stepwise regression models, for examining the validity of results. Logit, probit, and complementary log-log regressions were also employed for a relative analysis. R&D expenditures in the prior year, the interaction effect between the previous R&D intensity and high-tech sector, firm size, and growth rate were significant to determine R&D intensity. Moreover, a majority of explanatory variables were found to change between the years 2011 and 2018, while time-lagged effects between the R&D intensity and growth rate exist. Results of the study are expected to be used for future research to detect optimal levels of R&D expenditures for the value maximization of SMEs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.261-267
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• 2020

The demand for faster, lighter, and thinner portable electronic devices has brought about a change in semiconductor packaging technology. In response, a stacked chip-scale package(SCSP) is used widely in the assembly industry. One of the key materials for SCSP is a die-attach film (DAF). Excellent flowability is needed for DAF for successful die attachment without voids. For DAF with high flowability, two-step curing is often required to reduce a cure crack, but one-step curing is needed to reduce the processing time. In this study, DAF composition was categorized into three groups: cure (epoxy resins), soft (rubbers), hard (phenoxy resin, silica) component. The effect of the composition on a cure crack was examined when one-step curing was applied. The die-attach void and flowability were also assessed. The cure crack decreased as the amount of hard components decreased. Die-attach voids also decreased as the amount of hard components decreased. Moreover, the decrease in cure component became important when the amount of hard component was small. The flowability was evaluated using high-temperature storage modulus and bleed-out. A decrease in the amount of hard components was critical for the low storage modulus at 100℃. An increase in cure component and a decrease in hard component were important for the high bleed-out at 120℃(BL-120).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.434-439
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• 2020

Selective laser melting (SLM) manufactures an alloy using laser as a heat source, and has recently been introduced in the dental industry. However, there is a lack of analytical research on metal-ceramic restorations achieved by SLM. This study evaluates and compares the metal-ceramic bond strength of Co-Cr alloys produced by selective laser melting and casting methods. Co-Cr samples required for this study were produced through the sintering process of ceramics, by applying the SLM and CAST methods. The metal-ceramic bond strength was measured by applying the shear bond strength test. In order to determine the area fraction of adherent ceramic, Si content of the specimen was measured using scanning electron microscopy SEM/ EDS. Results of the metal-ceramic bond strength and AFAC were analyzed by t-test (α = 0.05). No significant difference was observed comparing the bond strength of SLM and CAST Co-Cr alloys (P> 0.05). However, the SLM group had much better ceramic adherence than the CAST group (P < 0.001). Moreover, oxidation characteristics were similar for both SLM and CAST Co-Cr alloys, but metal structures were different. These results imply that although the bond of ceramic and Co-Cr alloy is not related to the manufacturing method, SLM alloys impart better ceramic adherence. This indicates that alloys made with SLM can be used to fabricate upper implant prostheses in the future. In particular, it is expected to overcome the shortcomings of the CAST method, and save time and cost.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.446-452
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• 2021

As a higher standard for food consumption is required, the consumption of chicken meat that can satisfy the subdivided food preferences is increasing. In March 2003, the quality criteria for chicken carcasses notified by the Livestock Quality Assessment Service suggested quality grades according to fecal contamination and the size and weight of blood and bruises. On the other hand, it is too difficult for human inspection to qualify mass products, which is key to maintaining consistency for grading thousands of chicken carcasses. This paper proposed the computer vision algorithm as a non-destructive inspection, which can identify chicken carcass parts according to the detailed standards. To inspect the chicken carcasses conveyed at high speed, the image calibration was involved in providing robustness to the side effect of external lighting interference. The separation between chicken and background was achieved by a series of image processing, such as binarization based on Expectation Maximization, Erosion, and Labeling. In terms of shape analysis of chicken carcasses, the features are presented to reveal geometric information. After applying the algorithm to 78 chicken carcass samples, the algorithm was effective in segmenting chicken carcass against a background and analyzing its geometric features.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.597-602
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• 2021

Even in the era of the 4th industrial revolution, the prevention of industrial accidents is still an important issue in industrial sites. In solving the problem of industrial safety, a product can be difficult to market if there is a lack of standard or method for a reliable performance evaluation. The purpose of this study was to develop and evaluate a test method for a wearable airbag product for protecting the body from falls that was newly developed to respond to fall accidents in industrial sites. As a research method, reliable evaluation standards were developed and applied through four stages of the evaluation and development process (Step 1: Product review, Step 2: Data research, Step 3: Expert meeting, Step 4: Drawing evaluation standard). In addition, the impact force was evaluated according to the developed evaluation standard. The fall impact force obtained through the evaluation showed a reduction effect of approximately 96% compared to the existing impact force. Therefore, the fall impact force was reduced significantly when the airbag was applied. This will enable new convergence products to be launched on the market and produce an environment where industrial workers can work safely.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.429-438
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• 2021

Owing to the development of science technology, particularly the smart concept and defense policy factors of the 4th industry, military weapon systems are advanced, and the scientific and operational force is reduced dramatically. The aspect of the future war is characterized by the operation of troops with reduced forces from advanced and scientific weapon systems in an operational area that has expanded more than four times compared to the present. Reflecting on these situational factors, it is necessary to improve combat methods based on the changes in the battlefield environment and advanced weapon systems. In this study, to find a more efficient future combat method in a changing war pattern, this study applied the battle experiment methodology using Vision21 war game model, which is an analytical model used by the army. Finally, this study aimed to verify the future combat method and unit structure. Therefore, the scenario composition and experiment method that reflect the change in the ground operational environment and weapon system was first composed. Subsequently, an analysis method based on the combat effectiveness was applied to verify the effective combat performance method and unit structure of future infantry units.