• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.1
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• pp.39-48
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• 2022

Many piping systems installed in the power plant are directly related to the safety and operation of the plant. Various dampers have been applied to the piping system to reduce the damage caused by earthquakes. In order to reduce the vibration of the piping system, this study developed a steel coil damper (SCD) with a straightforward structure but excellent damping performance. SCD reduces the vibration of the objective structure by hysteretic damping. The new SCD damper can be applied to high-temperature environments since it consists of steel members. The paper introduces a design method for the elastoplastic coil spring, which is the critical element of SCD. The practical applicability of the design procedure was validated by comparing the nonlinear force-displacement curves calculated by design equations with the results obtained from nonlinear finite element analysis and repeated loading test. It was found that the designed SCD's have a damping ratio higher than 25%. In addition, this study performed a set of seismic tests using a shaking table with an existing piping system to verify the vibration control capacity on the piping system by SCD. Test results prove that the SCD can effectively control the displacement vibration of the piping system up to 80%.

• The Journal of Economics, Marketing and Management
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• v.11 no.2
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• pp.33-46
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• 2023

Purpose: The purpose of this study is to analyze the relationship between characteristics of social media sites (SNS) and the intention of Pakistani tourists to visit South Korea while determining the role of usefulness, interestingness, and involvement of tourists. Research design, data and methodology: A research model was developed through the previous research, and the questioner-based survey was conducted on Pakistani tourists visiting Korea. The survey data was collected by following multiple hypotheses: the relationship between SNS tourism information and perception of SNS, the relationship between SNS perception and intention to visit, and adjustment of involvement in the relation between tourism information characteristics, and SNS perception. We used SPSS and AMOS24.0 statistical tools to analyze the hypothesis testing data. Results: Based on the data analysis, the study found that the characteristics of SNS have a positive effect on intention to visit via users' perception like usefulness and interestingness. The involvement has a moderating effect between SNS characteristics and users' perception. In the group with high involvement, the degree of influence of the quality factor of SNS on user perception was greater than in the group with low involvement. Conclusions: This study demonstrated that traveler's involvement has a moderating effect on the relationship between SNS characteristics and visit intention for Pakistani travelers visiting Korea. It shows that practitioners or researchers should establish and operate SNS strategies in consideration of user involvement.

• Current Optics and Photonics
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• v.7 no.6
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• pp.755-760
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• 2023

In this paper, an illumination optical system that can mitigate the saturation phenomenon in the center of an image (caused by the typical flexible-endoscope illumination system using LEDs with Lambertian light distribution) is designed. When an LED with Lambertian light distribution is used as a light source, the amount of light in the center of the endoscopic illumination system is relatively high, compared to the periphery, causing saturation in the image. Since this phenomenon causes difficulty in detecting the patient's lesion, it is necessary to find a lighting-system design that can alleviate the saturation phenomenon. Therefore, in this paper a lighting system with bat-wing light distribution, which can lower the intensity at the center and secure the maximum amount of light at the maximum light distribution angle, is designed. In addition, to check the performance of the designed lighting system, a simulation of illumination and luminance is conducted for a system using a common aspherical lens with otherwise the same components. As a result, it is confirmed that the lighting system designed in this paper effectively reduces the luminance value at the center and secures more luminance values at the periphery than the familiar lighting system.

• The Journal of Economics, Marketing and Management
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• v.12 no.4
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• pp.51-64
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• 2024

Recent studies have introduced that digital transformation positively impacts firm performance. However, research on the relationship between organizational capabilities or attitudes as antecedents or situational variables for successfully driving digital transformation remains limited. Therefore, this study aims to systematically analyze how dynamic digital capabilities and the mutual relationships between organizational members' digital acceptance influence firm performance throughout the process of driving and achieving digital transformation. Research design, data, and methodology: This study developed the concepts and measurement items for each variable based on prior research. A survey was conducted with 258 companies participating in mini clusters within industrial complexes across the county. The data was analyzed using a structural equation model with the AMOS software package. Results: Based on existing literature, hypotheses were formulated regarding the causal relationships among variables, and analysis was conducted. The results indicate that digital transformation and employees' technological acceptance play a mediating role in the relationship between dynamic digital capabilities and firm performance. Specifically, the organization's dynamic digital capabilities enhance both digital transformation and technological acceptance. Moreover, digital transformation leads to higher firm performance when technological acceptance is high. Conclusions: This study has shown the importance of enhancing dynamic digital capabilities as a prerequisite for driving digital transformation and highlighted the significance of organizational members' perceptions and attitudes toward information technology. Particularly, through detailed causal analysis among the specific items of each variable, insights were gained for both academic and practical applications.

• Journal of the Korean Society for Railway
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• v.2 no.3
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• pp.5-7
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• 1999

Ten years have passed since my last visit to Korea on the occasion of the International Symposium on High Speed Rail Systems organized by the Korean Transport Institute in October 1989. At that time, it was the objective to introduce the maglev and VHSR (very high speed rail) systems with their different areas of application and to discuss them with local partners against the background of the Seoul-Pusan HSR project. Congratulations on the success of the Centennial seminar. I am much pleased to be invited to the memorable seminar and I would like to express my sincere gratitude to Korean members' hospitality. (omitted)

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.407-409
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• 1995

CS PWM converter is appropriate for the high power and high precision current control. The input/output filters of the CS PWM converter limit the output DC current range and may destroy the system with filter resonance, and make the system equation more complicated. In this paper, the systematic and simple filter design method which considers not only the harmonic attenuation but the total system performance also is proposed.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.177-184
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• 2015

In order to use the high-volume slag cement as a construction materials, a proper activator which can improve the latent hydraulic reactivity is required. The dissolved aluminum silicon ions from ground granulated blast furnace slag (GGBFS) react with sulfate ions to form ettringite. The proper formation of ettringite can increase the early-age strength of high-volume GGBFS (80%) cement. The aim of this study is to investigate the hydration properties with sulfate activators (sodium sulfate, anhydrite). In this paper, the effects of $Na_2SO_4$ and $CaSO_4$ on setting, compressive strength, hydration, micro-structure were investigated in high-volume GGBFS cement and compared with those of without activator. Test results indicate that equivalent $SO_3$ content of 3~5% improve the early-age hydration properties such as compressive strength, heat evolution rate, micro-pore structure in high-volume GGBFS cement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.1-7
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• 2017

This study investigates the high-frequency heat treatment characteristics with the distance between a coil and SCM440 parts for an automobile. Global automobile makers are focusing on research to develop high-performance automobiles with improved fuel efficiency and lower emissions in accordance with consumer demand and environmental policies. However, most research on high-frequency heat treatment has been experimental, and it is very difficult to obtain high-frequency heat treatment conditions for a specific product. Therefore, all the conditions of high-frequency heat treatment except the distance between a coil and SCM440 parts were kept the same. As a result, the optimized distance between the coil and SCM440 parts was observed to be 1-2 mm. When the distance between the coil and SCM440 parts was over 3 mm, the effective case hardness depth and total case hardness depth did not satisfy the standards.

• Journal of Advanced Technology Convergence
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• v.2 no.4
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• pp.13-19
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• 2023

Following the signing of the Paris Agreement on Climate Change (UNFCCC, 2015), the world is expanding greenhouse gas reduction activities through comprehensive participation that includes not only developed countries but also developing countries. Major countries around the world are placing high expectations on the effectiveness of total carbon emissions regulation through the carbon emissions market. However, in order to obtain carbon credits, third-party verification is required based on quantitative carbon reduction data. Accordingly, in this paper, we developed an AIoT high-efficiency street light for carbon emissions and conducted a performance analysis study to measure the luminous efficiency of the lighting fixture. To obtain carbon emissions rights, we used high-efficiency LED PKG, developed our own high-voltage PFC, and developed high-efficiency lighting fixtures capable of communication. For communication, the 2.4GHz LoRa method was adopted between the lighting fixture and the gateway. Lens design was conducted through simulation of Korea Expressway Corporation's standard streetlight types A, B, and C. The performance of the streetlight was verified as being more efficient than other existing products through the measurement of luminous efficiency by an accredited rating agency, and it is expected that carbon emissions rights will be obtained by reducing electrical energy through this.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.76-91
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• 2019

There have been many studies to examine the patterns in innovations reflecting industry-specific characteristics from an evolutionary economics perspective. The purpose of this study is to identify industry-specific differences in product innovation patterns and determinants of innovation performance. For this, Korean manufacturing is classified into high-tech industries and low-tech industries according to technology intensity. It is also pointed out that existing research does not reflect the decision-making process of firms' R&D implementations. In order to solve this problem, this study presents a Heckman sample selection model and a double-hurdle model as alternatives, and analyzes data from 1,637 firms in the 2014 Survey on Technology of SMEs. As a result, it was confirmed that the determinants and patterns of manufacturing in small and medium-size enterprise (SME) product innovation are significantly different between high-tech and low-tech industries. Also, through an extended empirical model, we found that there exist a sample selection bias and a hurdle-like threshold in the decision-making process. In this study, the industry-specific features and patterns of product innovation are examined from a multi-sided perspective, and it is meaningful that the decision-making process for manufacturing SMEs' R&D performance can be better understood.