Young Eun Song

Reaction force estimation of surgical robot instrument using perturbation observer with SMCSPO algorithm

This paper proposes a sensorless force estimation method for the end effector tip of a surgical robot instrument. Due to various size and safety constraints related to the surgical robot instrument, it is difficult to measure the reaction force at the instrument tip. This paper presents a method of estimating the reaction force of the surgical robot instrument without sensors and attempts to use state observer of control algorithm. Sliding mode control with sliding perturbation observer (SMCSPO) is used to drive the instrument, where the sliding perturbation observer (SPO) computes the amount of perturbation defined as the combination of the uncertainties and nonlinear terms where the major uncertainties arise from the reaction force. Based on this idea, this paper proposes a method to estimate the reaction force on the end-effector tip of the surgical robot instruments using only SPO and encoder without any additional sensors. To evaluate the validity of this paper, experiment was performed and the results showed that the estimated force computed from SPO is similar to the actual force.

Recent applications of bioelectrochemical system for useful resource recovery: retrieval of nutrient and metal from wastewater

Sustainable energy and carbon neutrality has been a key issue in waste/wastewater management. Recovery and recycling of materials such as nutrients and metal are highly anticipated to achieve a zero-energy treatment and pollution control, and subsequently secure sustainability of exhausted resources. The difficulty of resource recovery from waste/wastewater and sediment is mainly due to the immature technology, and dispersed (or less concentrated) target resources in wastewater and natural source that results in technical challenges and poor economics. Bioelectrochemical system (BES) has been widely investigated for electrical energy recovery, intermediate chemical production and recently for useful resource recovery. Certain amounts of energy in wastewater can be used as reducing power for energy production as well as for useful material recovery from wastewater and natural sources using a novel inter-disciplinary biotechnology, BES simultaneously treating wastewater.

Electrochemically enhanced microbial CO conversion to volatile fatty acids using neutral red as an electron mediator.

Conversion of C1 gas feedstock, including carbon monoxide (CO), into useful platform chemicals has attracted considerable interest in industrial biotechnology. Nevertheless, the low conversion yield and/or growth rate of CO-utilizing microbes make it difficult to develop a C1 gas biorefinery process. The Wood-Ljungdahl pathway which utilize CO is a pathway suffered from insufficient electron supply, in which the conversion can be increased further when an additional electron source like carbohydrate or hydrogen is provided. In this study, electrode-based electron transference using a bioelectrochemical system (BES) was examined to compensate for the insufficient reducing equivalent and increase the production of volatile fatty acids. The BES including neutral red (BES-NR), which facilitated electron transfer between bacteria and electrode, was compared with BES without neutral red and open circuit control. The coulombic efficiency based on the current input to the system and the electrons recovered into VFAs, was significantly higher in BES-NR than the control. These results suggest that the carbon electrode provides a platform to regulate the redox balance for improving the bioconversion of CO, and amending the conventional C1 gas fermentation.

Biologically activated graphite fiber electrode for autotrophic acetate production from CO2in a bioelectrochemical system

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Co-culture-based biological carbon monoxide conversion by Citrobacter amalonaticus Y19 and Sporomusa ovata via a reducing-equivalent transfer mediator

The biological conversion of carbon monoxide (CO) has been highlighted for the development of a C1 gas biorefinery process. Despite this, the toxicity and low reducing equivalent of CO uptake make biological conversion difficult. The use of synthetic co-cultures is an alternative way of enhancing the performance of CO bioconversion. This study evaluated a synthetic co-culture consisting of Citrobacter amalonaticus Y19 and Sporomusa ovata for acetate production from CO. In this consortium, the CO2 and H2 produced by the water-gas shift reaction of C. amalonaticus Y19, were utilized further by S. ovata. Higher acetate production was achieved in the co-culture system compared to the monoculture counterparts. Furthermore, syntrophic cooperation via various reducing equivalent carriers provided new insights into the synergistic metabolic benefits with a toxic and refractory substrate, such as CO. This study also suggests an appropriate model for examining the syntrophic interaction between microbial species in a mixed community.