• Journal of Drive and Control
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• v.18 no.4
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• pp.77-83
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• 2021

With the progress in virtual reality technology, various virtual objects can be displayed using head-mounted displays (HMD). However, force feedback sensations such as pushing against a virtual object are not possible with an HMD only. Focusing on force feedback, desktop-type devices are generally used, but the user cannot move in a virtual space because such devices are fixed on a desk. With a wearable force feedback device, users can move around while experiencing force feedback. Therefore, the authors have developed a wearable force feedback device using a magnetorheological fluid clutch and pneumatic rubber artificial muscle, aiming at presenting the elasticity, friction, and viscosity of an object. To date, we have developed a wearable four-degree-of-freedom (4-DOF) force feedback device and have quantitatively evaluated that it can present commanded elastic, frictional, and viscous forces to the end effector. However, sensory evaluation with a human has not been performed. In this paper, therefore, we conduct a sensory evaluation of the proposed method. In the experiment, frictional and viscous forces are rendered in a virtual space using a 4-DOF force feedback device. Subjects are asked to answer questions on a 1- to 7-point scale, from 1 (not at all) to 4 (neither) to 7 (strongly). The Wilcoxon signed rank test was used for all data, and answer 4 (neither) was used as compared standard data. The experimental results confirmed that the user could feel the presence or absence of viscous and frictional forces. However, the magnitude of those forces was not sensed correctly.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.685-692
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• 1991

The pool boiling behavior of a heated surface has been investigated experimentally, focusing on the cases when only a part of the contact surface is heated. Characteristic boiling curves are obtained with circular metal surface test pieces heated below while immersed in Refrigerant-113. Locally heated test pieces are fabricated by inserting a heating block at the center inside a larger conducting block. Overall heat transfer rates are measured while the experimental conditions are systematically varied. The local temperature profiles along the radius are measured for conducting blocks. It is found that the conjugated boiling condition exists and the total heat fluxes should be correlated to a suitably defined temperature difference.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.05a
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• pp.134-138
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• 2005

Recently many researches related with biotechnology are processed and it is the situation that research about micro fluidic devices is active. Micro fluidic devices has been one of the most widely used devices for the analysis in biotechnology because they have many advantages, flexibility, transparency, thermal and electrical stability, nontoxic, etc. In this study, micro fluidic device with PDMS is developed for particle counter which separates a small quantity of particles, The principle of micro particle counter is electrical-impedance method, and it was also applied hydrodynamic flow focusing. It is more efficient method to analyzing particles furthermore it can be applied to cell count ins for biotechnology.

• Ceramist
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• v.23 no.2
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• pp.145-165
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• 2020

Halide perovskites are promising photovoltaic materials due to their excellent optoelectronic properties like high absorption coefficient, low exciton binding energy and long diffusion length, and single-junction solar cells consisting of them have shown a high certified efficiency of 25.2%. Despite of high efficiency, perovskite photovoltaics show poor stability under actual operational condition, which is the mostly critical obstacle for commercialization. Given that the stability of the perovskite devices is significantly affected by charge-transporting layers, the use of inorganic charge-transporting layers with better intrinsic stability than the organic counterparts must be beneficial to the enhanced device reliability. In this review article, we summarized a number of studies on the inorganic charge-transporting layers of the perovskite solar cells, especially focusing on their effects on the enhanced device reliability.

• Journal of Advanced Engineering and Technology
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• v.10 no.2
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• pp.203-208
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• 2017

Due to global climate change issues, there is a growing demand for systems throughout the industry. In the case of power conversion, studies have been actively conducted to change the structure of the power conversion circuit and to apply new power devices. In particular, the WBG (Wide Band Gap), which is newly emerged device in the market for developing semiconductor technology, has demonstrated advantages in applying for various aspects in comparison to the existing Si (Silicon) Semiconductor. Recent research centers in the railway industry are focusing on developing technologies suitable for railway vehicles by utilizing these new developments in railway countries such as Japan and Europe. This paper researches the WBG device that is applicable to the auxiliary power supplies (APS) in railway system, and analyzes the downsizing effects to APS in high-speed railway by conducting a theoretical analysis and simulation.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.1
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• pp.17-24
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• 2020

As an interconnect scaling faces a technical bottleneck, the device stacking technologies have been developed for miniaturization, low cost and high performance. To manufacture a stacked device structure, a vertical interconnect becomes a key process to enable signal and power integrities. Most bonding materials used in stacked structures are currently solder or Cu pillar with Sn cap, but copper is emerging as the most important bonding material due to fine-pitch patternability and high electrical performance. Copper bonding has advantages such as CMOS compatible process, high electrical and thermal conductivities, and excellent mechanical integrity, but it has major disadvantages of high bonding temperature, quick oxidation, and planarization requirement. There are many copper bonding processes such as dielectric bonding, copper direct bonding, copper-oxide hybrid bonding, copper-polymer hybrid bonding, etc.. As copper bonding evolves, copper-oxide hybrid bonding is considered as the most promising bonding process for vertically stacked device structure. This paper reviews current research trends of copper bonding focusing on the key process of Cu-SiO₂ hybrid bonding.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.4
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• pp.332-337
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• 2013

This paper presents a subsequent research work on the roller design of IRB(isolation roller bearing) seismic isolation device presented in Part 1 by focusing on heat treatment. The hardness and friction factor are very important factors of material and after-treatment process selection. Normally, roller bearing consists of roller and retainer. The roller gets high pressure constantly, while the retainer gets tensile and compressive stress. Therefore, sensitive material selection and heat treatment of each part is quite important. In this experimental evaluation, carbon steel, chrome special steel and others are employed and their characteristics after heat treatment are identified. Each material is prepared by refining high frequency heat treatment. The friction factor and static load capacity of manufactured material are experimentally identified and destructive test of material is processed. Optimal material and heat treatment conditions for IRB roller bearing are determined based on experiment results.

• Journal of Biomedical Engineering Research
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• v.38 no.4
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• pp.205-210
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• 2017

The convergence healthcare industry in Korea has been stalled due to conflicts between stakeholders as well as a supplier-centered industry structure. This situation is caused by the structural contradiction in which the Korean industry has a prolonged conflict structure among stakeholders due to a strong regulation and an institutional inertia from the viewpoint of the sociotechnical system. Therefore, it is necessary to identify new system management plan that enhances social acceptability such as laws, customs and ideas while reducing conflicts between stakeholders. In this study, mainly adapting the stakeholder-oriented autopoiesis and focusing on publicness of healthcare, we propose the rationale and direction for policy making to harmonize various systems within the convergence healthcare industry.

• Journal of Semiconductor Engineering
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• v.1 no.1
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• pp.57-63
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• 2020

Complementary metal-oxide-semiconductor (CMOS) technology is now facing a power scaling limit to increase integration density. Since 1970s, multi-valued logic (MVL) has been considered as promising alternative to resolve power scaling challenge for increasing information density up to peta-scale level by reducing the system complexity. Over the past several decades, however, a power-scalable and mass-producible MVL technology has been absent so that MVL circuit and system implementation have been delayed. Recently, compact MVL device researches incorporating multiple-switching characteristics in a single device such as 2D heterojunction-based negative-differential resistance (NDR)/transconductance (NDT) devices and quantum-dot/superlattices-based constant intermediate current have been actively performed. Meanwhile, wafer-scale, energy-efficient and variation-tolerant ternary-CMOS (T-CMOS) technology has been demonstrated through commercial foundry. In this review paper, an overview for MVL development history including recent studies will be presented. Then, the status and its future research direction of MVL technology will be discussed focusing on the T-CMOS technology for peta-scale information processing in semiconductor chip.

• The Journal of Information Systems
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• v.28 no.2
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• pp.129-152
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• 2019

Purpose The purpose of this study is to empirically identify the risky behavior of mobile device users using the Internet of Things on a situational perspective. Design/methodology/approach This study made a design of the research model based on model of the determinants of risk behavior. Data were collected through a survey including hypothetical scenario. SmartPLS 2.0 was used for the structural model analysis and t-test was conducted to compare the between normal and situational behavior. Findings The results were as follows. First, the central roles of risk propriety and risk perception were verified empirically. Second, we identified the role of locus of control as a new factor of impact on risky behavior. Third, mobile risk propensity has been shown to increase risk perception. Fouth, it has been shown that risk perception does not directly affect risky behavior and reduce the relationship between mobile risk propensity and risk behavior. According to the empirical analysis result, Determinants of risk behavior for mobile users were identified based on a theoretical framework. And it raised the need to pay attention to the impact of locus of control on risk behavior in the IS security field. It provided direction to the approach to risky behavior of mobile device users. In addition, this study confirmed that there was a possibility of taking risky behavior in the actual decision-making.