• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.2
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• pp.108-111
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• 2011

The semiconducting material of ZnO in II-VI group was well known as its good application for photo electronics, chemical sensors and field effect transistors due to the remarkable optical properties with wide energy band gap and great ionic reactivities. Up to now the growth of a good quality of ZnO film has been issued for better performances. Even though there were many deposition methods for making ZnO films, pulse laser deposition methods have been preferred for high crystalline films. In this report, the ZnO film was also created by pulsed laser deposition technique which also showed high crystalinity. By controlling several factors when deposited, it was investigated that the optimal condition for ZnO film formation. Mainly, oxygen partial pressures and growth temperatures were changed when ZnO films were synthesized and followed the characterization by HRXRD and AFM.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1451-1456
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• 2013

This paper presents the improved zero power levitation control algorithm for a quadruple hybrid EMS (Electromagnetic Suspension) system. Quadruple hybrid EMS system is a united form of four hybrid EMS systems one on each corner coupled with a metal plate. Technical issue in controlling a quadruple hybrid EMS system is the permanent magnet's equilibrium point deviation caused by design tolerance which eventually leads to a limited zero power levitation control that only satisfies the zero power levitation in one or two hybrid EMS system among the four hybrid EMS system. In order to satisfy a complete zero power levitation control of the quadruple hybrid EMS system, the proposed method presented in this paper adds a compensating algorithm which adjusts the gap reference of each individual axe. Later, this paper proves the stability and effectiveness of the proposed control algorithm via experiment and disturbance test.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.753-761
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• 2014

We propose a two-step UV irradiation procedure to fabricate polymer-dispersed liquid crystal (PDLC) films by lamination. During the first UV treatment, before lamination, the UV-curable monomers coated on one film substrate are solidified through photo-polymerization as the phase separation between the liquid crystals and the monomers. Introducing an adhesion-enhancement layer on the other plastic substrate and controlling the UV irradiation conditions ensure that UV-induced cross-linkable functional groups remain on the surfaces of the photo-polymerized layers. Thereby, the adhesion stability between the top and bottom films is much improved during a second (post-lamination) UV treatment by further UV-induced cross-linking at the interface. Because the adhesion-enhancement and PDLC layers prepared by the bar-coating process are solidified before lamination, the PDLC droplet distribution and the cell gap between the two plastic substrates remain uniform under the lamination pressure. This ensures that the voltage-controlled light transmittance is uniform across the entire sample.

• Earthquakes and Structures
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• v.4 no.5
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• pp.471-487
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• 2013

Performance of a prototype base isolated building located at Indian Institute of Technology, Guwahati (IITG) has been studied here. Two numbers of three storeyed single bay RCC framed prototype buildings were constructed for experimental purpose at IITG, one supported on conventional isolated footings and the other on a seismic isolation system, consisting of lead plug bearings. Force balance accelerometers and a 12 channel strong motion recorder have been used for recording building response during seismic events. Floor responses from these buildings show amplification for the conventional building while 60 to 70% reduction has been observed for the isolated building. Numerical models of both the buildings have been created in SAP2000 Nonlinear. Infill walls have been modeled as compression struts and have been incorporated into the 3D models using Gap elements. System identification of the recorded data has been carried out using Parametric State Space Modeling (N4SID) and the numerical models have been updated accordingly. The study demonstrates the effectiveness of base isolation systems in controlling seismic response of isolated buildings thereby leading to increased levels of seismic protection. The numerical models calibrated by relatively low level of earthquake shaking provides the starting point for modeling the non-linear response of the building when subjected to strong shaking.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.11
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• pp.713-719
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• 2000

This paper presents an approach toward improving the performance of Moving Coil Type Linear Oscillatory Actuator (MC-LOA) with the application of Finite Element Method (FEM) to a simple control system. MC-LOA has an unbalanced magnetic circuit due to its asymmetric structure and there is a different flux distribution on the air-gap along the current direction. The interaction driven by two fluxes between the Permanent Magnet (PM) and the current causes the unbalanced thrust and interferes with the proper oscillation of MC-LOA. In order to solve the above problems and improve the driving performance, it is necessary to analyze the rate of the unbalanced thrust according to the current direction by using FEM. Then, the analysis results are used to determine the input currents for both directions. Controlling the input currents can be easily achieved by a simple control system, such as Pulse Width Modulation (PWM), without complex units. The validity of the approach is verified by the experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.172-179
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• 2000

In this paper a technology for the fabrication of the oblique structure using the LIGA process will be presented. The fabricated microstructure is a tetrahedral 3- facet mirror. The mirror has an equilateral triangular base of hundreds ${\mu}m$ length mirror-like three side-facets inclined to the base at 45$^{\circ}$ and knife edges. Two regular triangles of 45$^{\circ}$ and tan-12. After development the shaded part of the PMMA the tetrahedral mirror remains, The completed mirror shows excellent aspects of mirror-like facets and knife-edges. By controlling the gap between the mask and the substrate the size of mirror easily can be changed. This mirror would be used as a laser beam splitter for the feedback control of the HDD slider.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.36 no.4
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• pp.103-111
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• 2020

Perforated metal sheets are used as panels of facades for controlling environmental factors while ensuring user's visibility. Despite their functional potentials, only a specific direction of facades or an orientation of a building was considered in the relevant studies. This study proposed a design methodology for the perforated panel facades that reflects the location on the facades and the user's requirements. The optimization of quantitative and qualitative performance is achieved through communication between designers and users in a VR system. In optimizing quantitative performances, designers use machine learning techniques such as clustering and genetic algorithm to allocate optimal panels on the facades. In optimizing qualitative performances, through the VR system, users intervene in evaluating performances whose preferences are depending on them. The experiment using the office project showed that designers were able to make decisions based on clustering using GMM to optimize multiple quantitative performances. The gap between the target and final performance could be narrowed by limiting the types of perforated panels considering mass customization. In assessing visibility as a qualitative performance, users were able to participate in the design process using the VR system.

• Journal of Korean Society for Quality Management
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• v.50 no.2
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• pp.221-233
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• 2022

Purpose: This study investigates how the salespersons behave in coordinating the multiple communication channels during supplier integration (SI) for new product development (NPD), especially when their engineers directly collaborate with the buyer. Methods: This study conducted a qualitative study to explore the dynamics of the supplier's salespersons during SI for NPD. With the support of a consumer goods manufacturer (focal firm) in South Korea, we interviewed several managers, including purchasing and engineering, from the focal firm and salespersons from eight tier-1 suppliers of the focal firm. Results: The results found that the supplier's salespersons show two different behaviors toward managing and controlling the collaboration between their engineers and the buyer: (1) Process regulating behaviors that control the flows of information or communication between the engineers and the buyer, and (2) knowledge regulating behaviors that directly and indirectly support the engineers to be equipped with accurate and complete knowledge so that they can share the right knowledge with the buyer. Conclusion: This study contributes to academia and practitioners as follows. To academia, this study fill the gap in the literature by introducing the distinct behaviors of the supplier's salesperson in SI for NPD. To practitioner, in addition, our findings present coordination mechanisms to manage and control multiple communications within an inter-organizational collaboration.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.127-136
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• 2024

Because the hazardous working environments and high labor intensity of the root industry can potentially impact the health of workers, current regulations have focused on measuring and controlling environmental factors, on a semi-annual basis. However, there is a lack of quantitative criteria addressing workers' health conditions other than the physical work environment. This gap makes it challenging to prevent occupational diseases resulting from continuous exposure to harmful substances below regulatory thresholds. Therefore, this paper proposes a machine learning-based method for determining the peak level of risk in root industry work environments and enables real-time safety assessment in workplaces utilizing this approach.

• Steel and Composite Structures
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• v.50 no.6
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• pp.721-734
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• 2024

In this research, the efficiency of a metallic energy dissipation device for seismic retrofit of an existing structure is evaluated by cyclic loading test. The proposed device, which is called multi-slit damper, is made of weak and strong slit dampers connected in series. Its energy dissipation mechanism consists of two stages: (i) yielding of the weak-slit damper under minor earthquakes; (ii) restraint of further deformations of the weak slit damper and activation of the strong slit damper under major earthquakes using a gap mechanism. A reinforced concrete (RC) frame with characteristics similar to soft-first-story structures is tested under cyclic loading before and after retrofit using the proposed device. The details of the experimental study are described and the test is simulated in an available commercial software to validate the analytical model of the damper. To further verify the applicability of the damper, it is applied to an analysis model of a 4-story structure with soft first story and its seismic performance is evaluated before and after retrofit. The experimental and analysis results show that the multi-slit damper is effective in controlling seismic response of structures.