• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.221-229
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• 2022

Sliding mode control (SMC) is a robust control method to control a robot arm with nonlinear properties. A high switching gain of SMC causes chattering problems, although the SMC allows the adequate control performance by giving high switching gain, without the exact robot model containing nonlinear and uncertainty terms. In order to solve this problem, SMC with sliding perturbation observer (SMCSPO) has been researched, where the method can reduce the chattering by compensating the perturbation, which is estimated by the observer, and then choosing a lower switching control gain of SMC. However, optimal gain tuning is necessary to get a better tracking performance and reducing a chattering. This paper proposes a method that the Q-learning automatically tunes the control gains of SMCSPO with an iterative operation. In this tuning method, the rewards of reinforcement learning (RL) are set minus tracking errors of states, and the action of RL is a change of control gain to maximize rewards whenever the iteration number of movements increases. The simple motion test for a 7-DOF robot arm was simulated in MATLAB program to prove this RL tuning algorithm. The simulation showed that this method can automatically tune the control gains for SMCSPO.

• Steel and Composite Structures
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• v.42 no.3
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• pp.299-313
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• 2022

Steel-concrete-steel composite structures with bidirectional webs (SCSBWs) are used in large-scale projects and exhibit good mechanical performances and constructional efficiency. The shear behaviors of SCSBW deep beam members in key joints or in locations subjected to concentrated forces are of concern in design. To address this issue, experimental program is investigated to examine the deep-beam shear behaviors of SCSBWs, in which the cracking process and force transfer mechanism are revealed. Compared with the previously proposed truss model, it is found that a strut-and-tie model is more suitable for describing the shear mechanism of SCSBW deep beams with a short span and sparse transverse webs. According to the experimental analyses, a new model is proposed to predict the shear capacities of SCSBW deep beams. This model uses strut-and-tie concept and introduces web shear and dowel action to consider the coupled multi mechanisms. A stress decomposition method is used to distinguish the contributions of different shear-transferring paths. Based on case studies, a simplified model is further developed, and the explicit solution is derived for design efficiency. The proposed models are verified using experimental data, which are proven to have good accuracy and efficiency and to be suitable for practical application.

• Structural Engineering and Mechanics
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• v.81 no.5
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• pp.591-606
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• 2022

When the friction pendulum system and shear keys work together to resist the ground motion, which inclined inputs (non 45°) to the bridge structure, the shear keys in XY direction will be sheared asynchronously, endowed the friction pendulum system with a violent curvilinear motion on the sliding surface during earthquakes. In view of this situation, firstly, this paper abandons the equivalent linearization model of friction and constructs a Spring-Coulomb friction plane isolation system with XY shear keys, and then makes a detailed mechanical analysis of the movement process of friction pendulum system, next, this paper establishes the mathematical model of structural time history response calculation by using the step-by-step integration method, finally, it compiles the corresponding computer program to realize the numerical calculation. The results show that the calculation method in this paper takes advantage of the characteristic that the friction force is always µmg, and creatively uses the "circle making method" to express the change process of the friction force and resultant force of the friction pendulum system in any calculation time step, which can effectively solve the temporal nonlinear action of the plane friction; Compared with the response obtained by the calculation method in this paper, the peak values of acceleration response and displacement response calculated by the unidirectional calculation model, which used in the traditional research of the friction pendulum system, are smaller, so the unidirectional calculation model is not safe.

• Research in Community and Public Health Nursing
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• v.33 no.2
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• pp.259-268
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• 2022

Purpose: In Cambodia, noncommunicable diseases (NCDs) account for 64% of all deaths. A lack of risk perception of NCDs leads to poor measures of their prevention and management. This study aimed to investigate Cambodians' risk perceptions of NCDs based on the health belief model. Methods: A cross-sectional design was used, and using convenience sampling, participants included 200 Cambodians aged 40 years or older. A face-to-face administered structured questionnaire was used to assess demographic characteristics, health behaviors, and risk perceptions of NCDs. Results: Of the constructs of NCD risk perception, perceived severity (88.2%) and benefits (86.3%) were high, but relative to these, perceived cues to action (64.1%), barriers (63.5%), and self-efficacy (58.1%) were low. Conclusion: It is important to improve perceived self-efficacy in government health promotion, outreach, and improvement programs and to reduce perceived barriers through medical tests either by facility-based delivery or via outreach health services in Cambodia.

• Asian Journal of Innovation and Policy
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• v.12 no.1
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• pp.001-026
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• 2023

This paper dealt with the Korean manpower policy in science and technology, focusing on the contents and tools of the Special Act and its Master Plans. After briefly introducing the historical development of the Korean manpower policy from the 1960s to the present, it discussed and analyzed the Special Act and Plans from the framework of personnel development, distribution, utilization and infrastructure. Korea's science and technology manpower policy has focused on fostering and supplying manpower in line with the country's industrial growth strategy. In the early stage of industrial development during the 1960s and 1980s, government research institutes were direct and effective tools for nurturing S&T manpower. Since the 1990s, the importance of university research has increased. The government fostered graduate research manpower through the research-oriented university policy of the BK21 program. After the IMF financial crisis in 1997, the tendency of students to avoid careers in science and technology led to enacting the Special Act (2004) governing the field of S&T human resources. The Special Act has contributed to leveling up the university education system in science and engineering and sophisticated the policy to include entrepreneurship training, spin-off startups, industry-university cooperation, and offering degree programs. The Special Act and the regularly revised Master Plans have been essential tools in systematically managing the science and technology manpower policies of the Korean government.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.1
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• pp.43-51
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• 2022

Platform lending or online lending, sometimes called peer-to-peer (P2P) lending, arose due to the digital revolution to meet people's requirements for simple fund borrowing. It quickly became an alternative to other traditional lending techniques, for example, loans banks. Along with the growth of P2P lending, several academics have investigated how information technology is used in financial services, emphasizing extended application methods. This study proposes an enhanced technology acceptance model (TAM) that investigates how consumers embrace P2P lending platforms by using quality of service and perceived risk as drivers of trust, relative advantage and compatibility as drivers of perceived usefulness. For the purpose of this study, we created a questionnaire, distributed it to clients of P2P lending platforms and fintech services in general in cities in Java, Indonesia. We received 290 replies to our questionnaire. The data was analyzed to test the hypotheses using structural equation modeling (SEM). The findings show that consumers' trust, relative advantage, perceived usefulness, and perceived ease of use in P2P lending platforms substantially affect their views toward adoption. The research's findings are useful for fine-tuning platform marketing strategies and putting strategic goals into action.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.661-669
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• 2009

Various kinds of shear connectors such as headed stud, channel, perforated steel plate and others are commonly used to transfer stress and conduct composite performance in steel concrete composite structures, and many researches have been conducted to improve the characteristics of different types of shear connectors. It is focused in this study on the pull-out and pushout performance of steel pipe pile cap with the open type perfobond for the composite connection to the spread footing. A parameter analysis was conducted, using ABAQUS, a nonlinear finite element analysis program, to obtain data for determining the characteristics of the structure and to allow various parametric analyses of steel pipe cap with the open perfobond.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.361-363
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• 2021

Digital character rigging is an important technology to improve animation vividness, and there are many kinds of complex ways of rigging system. To move naturally, the fish are tested for movement. Because 2,4 family role information although some, but the study of fish (0 family) action information is not much. As the diversity and complexity of fish production increases, inefficient time and capital are required. How to build a fish-like skeleton system depends on how to build an efficient and agile rigging program. The aim of this study is to compare the Advanced Skeleton-based animation process with Maya Rig, which can solve the high time-cost rigging problem, and to explore the best automatic plug-in based on the advantages of Advanced Skeleton, broadening the research scope of fish animation.

• Earthquakes and Structures
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• v.25 no.2
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• pp.113-123
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• 2023

A novel type of buckling restrained brace with built-up angle steel was developed. The core segment was formed by welding angle steel, and the middle section was reduced by cutting technology to solve the problem that the end of BRB was easy to buckle. The experimental program has been undertaken to study the performance of BRBs with different unbonded materials (silica gel, kraft paper) and different filler materials (ordinary concrete, full light-weight concrete). Four specimens were designed and fabricated for low cycle reciprocating load tests to simulate horizontal seismic action. The failure mode, hysteretic curves, tension-compression unbalance coefficient and other mechanical parameters were compared and analyzed. The finite element software ABAQUS was used to conduct numerical simulation, and the simulation results were compared with the experimental phenomena. The test results indicated that the hysteretic curve of each specimen was plump. Sustaining cumulative strains of each specimen was greater than the minimum value of 200 required by the code, which indicated the ductility of BRB was relatively good. The energy dissipation coefficient of the specimen with silica gel as unbonded material was about 13% higher than that with kraft paper. The experimental results were in good agreement with the simulation results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.197-204
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• 2006

This experimental study of prominent section bending behavior beam without shear connector provides bond capacity between concrete profile and initial stiffness of SC beam by comparing the test result with a theological analysis result and an ANSYS(common structural analysis program) analysis result. The compared result provides a fundamental study for practical use of efficient SC beam. Test result indicates 88%-98% rate of theological result in moment capacity and composition ratio shows 30%-70%. In other words, the results are insufficient to make a complete composite action. Therefore, it is need to make pull shear connection of connection method.