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An Enhanced Force Bounding Approach for Stable Haptic Interaction by Including Friction
백상윤,박상수,류제하 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.6
There is an inherent trade-off between stability and transparency in haptic interaction systems when interacting with virtual environments. Therefore, no perfect transparency can be displayed with absolute stability. For meaningful interactions, anyhow, some level of transparency is necessary for providing realistic feelings. On the other hand, robust stability must absolutely be guaranteed against any virtual environments because unstable behaviors disrupt contact realism completely and/or may also injure human operators. In order to increase magnitude transparency of the haptic interaction system, this paper proposes a way of systematic inclusion of Coulomb friction component in the previous force bounding approach. In the inclusion, two type of force bounding approach are derived. The less conservative condition can generate significantly higher magnitude transparency in terms of the initial contact crispness as well as the steady-state contact force for very stiff virtual objects. However, there occur some contact oscillations to diminish contact realism due to the energy accumulation during free motion. In order to avoid contact oscillations, a more conservative condition is proposed for systematically removing the past accumulated energy. The proposed algorithm is also compared with the other similar algorithm. Comprehensive experimental results are presented to show the effectiveness of the proposed approaches.
Fabricating Elastomeric Photomask with Nanosized-Metal Patterns for Near-Field Contact Printing
백상윤,김광묵,서동철,심우영 대한금속·재료학회 2021 대한금속·재료학회지 Vol.59 No.2
When an elastomeric photomask is used for near-field contact printing, the high deformability of the elastomer mask plate enables gap-free full contact with the substrate, minimizing the effect of diffraction. This image-transfer technique provides sub-50 nm resolution and depth-of-focus-free lithographic capability with cost-efficient equipment. However, the method’s application is limited due to the lack of a wellestablished protocol for fabricating a nanoscale mask pattern on an elastomeric substrate, which remains a major technical challenge in the field of near-field contact printing. In this study, we present a reliable protocol for fabricating a metal-embedded polydimethylsiloxane (PDMS) photomask. Our fabrication protocol uses conventional nanofabrication processes to fabricate nanosized chromium mask patterns and then transfers the chromium patterns to an elastomeric mask plate using a sacrificial Ni layer. Our protocol provides a high flexibility mask pattern design, and highly stable metal patterns during transferring process. By careful optimizing the experimental parameters, we determined a perfect pattern transfer ratio, which avoided any mechanical failure of the metal pattern, such as debonding or wrinkling. We then fabricated a PDMS photomask and confirmed its nanoscale patterning resolution, with the smallest feature 51 nm in width under a 400-nm light source. We anticipate that our fabrication protocol will enable the application of cost-efficient and high-resolution near-field photolithography.
“To All the Money I’ve Spent Before” : Why People Share their Bookkeeping Records with Strangers
김송현,백상윤,강연아 한국에이치씨아이학회 2020 한국HCI학회 논문지 Vol.15 No.2
This paper scrutinized online communities where users spontaneously shared their bookkeeping records. Unlike music or photos, it addressed phenomena in interacting with strangers about extremely personal and sensitive information. We analyzed why some users are willing to share data about their personal financial status and some are not. Based on our interviews, users in the online community can be categorized into four types. Regarding users' willingness to pay, we examined the motives behind the sharing of expenditure-tracking data even when a monthly fee is charged. This paper investigated the motivation and contextual reasons behind the sharing of such private and tricky data about one's financial status. Our findings explain the interaction necessary to facilitate exchange of transaction information and demonstrate that an anonymous online community can be utilized in the financial sector.