• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.632-637
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• 2021

In order to develop future construction technology, research is actively being conducted on concrete construction technology using 3D printing, which is currently in the spotlight as a future industry in domestic and foreign construction industries and academia. However, 3D printing technology is currently being developed and does not meet the requirements for proper construction technology and the properties of concrete materials, and it is difficult to apply in the actual field. Research is also needed for the durability management and maintenance of constructed structures. This work compares the compressive and flexural strength to that produced in conventional molds by dividing the 3D printed concrete output by the laminated X, Y, and Z axes. The compressive strength of a test specimen in the II Z-axis test direction was 8-10% higher than that of the other test directions (I and III Y axes and X axis). The strength was 4% lower than that of a molded test specimen. As of 28th of the age, the bending strength of the test specimen in the Z-axis direction was 5 to 7% higher than that of the I and III Y, and X-axis test directions, and the strength was 2% lower than that of the molded test specimen.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.417-425
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• 2020

Recently, the development of weapons systems in conjunction with the Fourth Industrial Revolution has increased the number of weapon systems that integrate individual commercial systems by actively incorporating the superior fields of private commercial technologies. In the case of such commercial product-based weapons systems, however, the development of ILS elements across all areas, such as technical manual, military field maintenance support equipment, interactive electronic technical manual (IETM), and Computer Based Training (CBT) development, and weapons system Reliability, Availability, Maintainability(RAM) target values, and logistics support analysis (LSA) was requested to expand the level of development by developers. The commercial product-based System Integration (SI) weapon system will be able to complete the comprehensive military balance for complementing and effective maintenance of the military and developers only when the ILS development, which is limited to the essential elements of the required group, Request For Proposal (RFP) and Post-Logistics Support (PLS) directions were applied in the framework of outsourcing maintenance implementation. As a result, by checking the operation status of current weapons systems, the logistics support of commercial product-based weapon systems selected outsourcing as the basic policy that is decided based on the development requirements, focusing on maintaining operation through a rational decision-making process, and presented a plan for applying the development plan to the RFP for the determined core elements and PLS.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.43-50
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• 2021

A Leg Mating Unit (LMU) is a device utilized during the float-over installation of offshore structures that include hyperelastic pads and mating part. The hyperelastic pads absorb the loads, whereas the mating part works as guidance between topside and supporting structures during the mating sequence of float-over installation. In this study, the design optimization of an LMU for the float-over installation of floating-type offshore structures is conducted to enhance the performance and to satisfy the requirements defined by classification society regulations. The initial dimensions of the LMU are referred to the dimensions of those used in fixed-type float-over installation because only the location and the number of LMUs are known. The two-parameter Mooney-Rivlin model is adopted to describe the hyperelastic pads under given material parameters. Geometric variables, such as the thickness, height, and width of members, as well as configuration variables, such as the angle and number of members, are defined as design variables and are parameterized. A sampling-based design sensitivity analysis based on latin hypercube sampling method is performed to filter the important design variables. The design optimization problem is formulated to minimize the total mass of the LMU under maximum von Mises stress and reaction force constraints.

• The Journal of Korean society of community based occupational therapy
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• v.10 no.3
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• pp.27-35
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• 2020

Objective : This study was to examine the effects of general characteristics and fall efficacy on health care program needs through a comparative analysis of general characteristics and health care program needs for the elderly. Methods : In this study, we analyzed data from 118 elderly people with t-test and ANOVA for comparison of fall effectiveness and health care program requirements and with regression for general characteristics and effects of fall effectiveness on health care program needs. Results : The results were as followed: First, there was a significant difference in gender(p=.00), age (p=.00),educational background(p=.00), and existence of spouse(p=.00), and no significant difference in income(p=.17) based on fall efficiency according to the general characteristics. There was a significant difference in gender(p=.00), age(p=.00), educational background(p=.00), and income(p=.00) and no significant difference in existence of spouse (p=.46) based on health care program needs according to the general characteristics. Second, it was shown that the higher age, the higher the income, the higher the effectiveness of the fall, and in case of woman, the more significant the effect of the exercise program had.. The explanation was 56 percent. Third, the higher the age, the higher the income, and the higher the fall efficiency, the more meaningful the cognitive program demand. The explanation was 48 percent. Conclusion : The data from this study showed the importance of fall efficacy in older people with significantly higher risk of falls than in other age groups, and the need for exercise and cognitive management programs to prevent falls.

• Korean Journal of Food Science and Technology
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• v.53 no.1
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• pp.78-84
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• 2021

As a calorie supplement for the elderly, functional beverages based on black sesame were prepared with different roasting times (0, 10, 15, and 20 min for R-0, R-10, R-15, and R-20, respectively), and their properties were compared. The total calorie content of the beverage was adjusted to match that of half a meal to meet the nutritional requirements of the elderly. The suspension stability of all samples was maintained for 5 day by the addition of xanthan gum. Regarding the color of the beverage, L* and a* values decreased, whereas b* increased with the increase in black sesame roasting time. Among the samples, the total lignan content did not change, except for R-20, which showed a significantly lower value than the others. Total polyphenol content significantly increased with roasting time, reaching the maximum value in R-15 and R-20; however, the free radical scavenging effect decreased for R-20. Based on the results of the sensory test, R-15 was the most acceptable for customized beverages.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.351-361
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• 2021

With the advent of the Fourth Industrial Revolution, the liberal arts education of universities has been called for fundamental innovation in its content and methods. H university has continuously made efforts to improve its general education curriculum with the goal of satisfying students' needs as well as the demands of the times. Its efforts can be summarized as the harmonization of competency-based education and the traditional liberal arts education. In more detail, it has tried to meet the demands of Ministry of Education which requests each university to establish its general education system focusing on key competencies. Simultaneously, it also radically changed its education system based on the guidelines of the Korea National Institute for General Education(KONIGE). The starting point of those changes was the basic consulting by KONIGE in 2017. According to the consulting report, H university introduced comprehensive and overall revision of its liberal arts education curriculum, increasing its liberal arts credit requirements from 22 to 28 credits in 2019. It has also reorganized and reclassified its liberal arts courses by introducing distributive elective classes. In 2020, in accordance with the guidelines of the Ministry of Education, H university altered its curriculum once more in order to establish a competency-based general education curriculum. Under the new curriculum, all requirement subjects are completely matched with key competencies of H university. It also includes newly opened courses and subject areas such as "Social Service" and "Global Citizenship." Through these changes, H university hopes that its general education contributes to fostering students equipped with key competencies, who can face actively this challenging period.

• Journal of Aerospace System Engineering
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• v.15 no.1
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• pp.86-94
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• 2021

PCB-based deployable solar panel is mainly used for CubeSat due to its lightweight and easy of electrical connection. However, as the size of solar panel increases, there is a limit to ensuring the structural safety of solar cells due to excessive dynamic displacement under launch vibration environment. In previous mechanical designs, for the minimization of dynamic deflection, panel stiffness is increased by applying additional stiffeners made of various materials such as aluminum or composite. However, it could have disadvantages for CubeSat design requirements due to limited mass and volumes. In this study, a high-damping 6U solar panel was proposed. It had superior damping characteristic with a multi-layered stiffener laminated with viscoelastic acrylic tapes. Basic characteristics of this solar panel were measured through free-vibration tests. Design effectiveness of the solar panel was validated through qualification-level launch vibration test. Based on test results, vibration characteristics of a typical PCB solar panel and the high-damping laminated solar panel were predicted and a comparative analysis was performed.

• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.89-92
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• 2020

According to the various IoT(Internet of Things) services, there have been lots of task offloading researches for IoT devices. Since there are service response delay and core network load issues in conventional cloud computing based offloadings, fog computing based offloading has been focused whose location is close to the IoT devices. However, even in the fog computing architecture, the load can be concentrated on the for computing node when the number of requests increase. To solve this problem, the opportunistic fog computing concept which offloads task to available computing resources such as cars and drones is introduced. In previous fog and opportunistic fog node researches, the offloading is performed immediately whenever the service request occurs. This means that the service requests can be offloaded to the opportunistic fog nodes only while they are available. However, if the service response delay requirement is satisfied, there is no need to offload the request immediately. In addition, the load can be distributed by making the best use of the opportunistic fog nodes. Therefore, this paper proposes a delayed offloading scheme to satisfy the response delay requirements and offload the request to the opportunistic fog nodes as efficiently as possible.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1323-1337
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• 2020

GEO-KOMPSAT-2A AMI (Advanced Meteorological Imager) radiometric calibration evaluation is an essential element not only for functional and performance verification of the payload but for the quality of the sensor data. AMI instrument consists of six reflective channels and ten thermal infrared ones. One of the key parameters representing radiometric properties of the sensor is a SNR (Signal-to-Noise Ratio) for the reflective channels and a NEdT (Noise Equivalent delta Temperature) for the IR ones respectively. Other important radiometric calibration parameters are a dynamic range and a gain value related with the responsivity of detectors. To verify major radiometric calibration performance of AMI, an offline radiometric evaluation tool was developed separately with a real-time AMI data processing system. Using the evaluation tool, validation activities were carried out during the GEO-KOMPSAT-2A In-Orbit Test period. The results from the evaluation tool were cross checked with those of the HARRIS, which is the AMI payload vendor. AMI radiometric evaluation activities were conducted through three phases for both sides (Side 1 and Side 2) of AMI payload. Results showed that performances of the key radiometric properties were outstanding with respect to the radiometric requirements of the payload. The effectiveness of the evaluation tool was verified as well.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.103-110
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• 2020

In the recent seismic design code KDS 41 17 00, selection and modification procedures of ground motions which are used for nonlinear dynamic analyses were adopted. However, its practical applications are still limited due to the lack of literatures. This paper introduces case studies which used site-response analyses to select and modify ground motions for nonlinear dynamic analyses. Based on the case studies, design criterion for site-response analyses were reviewed thoroughly in the viewpoint of practical applications. It was found that design requirements related with bedrock motions are too conservative that ground motions are selected and modified in the excessive manner. It is especially true for low-rise building structures with period ranges including acceleration-sensitive regions. Even though surface motions have shown appropriate responses, such building structures have to re-select and re-modify ground motions based on pre-analysis procedures rather than post-ones according to the current seismic design code. Also, it was observed that building structures with soft soils under strong ground motions need more comprehensive investigations on soil properties and efficient analysis methods in order to perform site-response analyses. This is due to the fact that lack of reliabilities on soil properties and analysis methods could result in unstable site-responses.