Sukho Park - Academia.edu (original) (raw)

Papers by Sukho Park

Biotechnology and applied biochemistry, Jan 31, 2015

To improve drug delivery efficiency in cancer therapy, many researchers have recently concentrate... more To improve drug delivery efficiency in cancer therapy, many researchers have recently concentrated on drug delivery systems that use anti-cancer drug loaded micro- or nanoparticles. In addition, induction methods, such as ultrasound, magnetic field, and infrared light, have been considered as active induction methods for drug delivery. Among these, focused ultrasound has been regarded as a promising candidate for the active induction method of drug delivery system because it can penetrate a deep site in soft tissue, and its energy can be focused on the targeted lesion. In this research, we employed focused ultrasound as an active induction method. For an anti-cancer drug loaded microparticles, we fabricated poly-lactic-co-glycolic acid-docetaxel (PLGA-DTX) nanoparticle encapsulated alginate microbeads using the single-emulsion technique and the aeration method. To select the appropriate operating parameter for the focused ultrasound, we measured the pressure and temperature induced ...

Biomicrofluidics, 2015

The bacteria-based microrobot (Bacteriobot) is one of the most effective vehicles for drug delive... more The bacteria-based microrobot (Bacteriobot) is one of the most effective vehicles for drug delivery systems. The bacteriobot consists of a microbead containing therapeutic drugs and bacteria as a sensor and an actuator that can target and guide the bacteriobot to its destination. Many researchers are developing bacteria-based microrobots and establishing the model. In spite of these efforts, a motility model for bacteriobots steered by chemotaxis remains elusive. Because bacterial movement is random and should be described using a stochastic model, bacterial response to the chemo-attractant is difficult to anticipate. In this research, we used a population-scale approach to overcome the main obstacle to the stochastic motion of single bacterium. Also known as Keller-Segel&amp;amp;amp;amp;amp;#39;s equation in chemotaxis research, the population-scale approach is not new. It is a well-designed model derived from transport theory and adaptable to any chemotaxis experiment. In addition, we have considered the self-propelled Brownian motion of the bacteriobot in order to represent its stochastic properties. From this perspective, we have proposed a new numerical modelling method combining chemotaxis and Brownian motion to create a bacteriobot model steered by chemotaxis. To obtain modeling parameters, we executed motility analyses of microbeads and bacteriobots without chemotactic steering as well as chemotactic steering analysis of the bacteriobots. The resulting proposed model shows sound agreement with experimental data with a confidence level &amp;amp;amp;amp;amp;lt;0.01.

Transactions of the Korean Society of Mechanical Engineers A, 2009

2004 IEEE International Conference on Robotics and Biomimetics, 2004

The conventional endoscopes generate pains and discomfort to patients due to the stiffness of the... more The conventional endoscopes generate pains and discomfort to patients due to the stiffness of their body and cannot reach to small intestines. Therefore, the wireless capsule-type endoscope, M2A, has been developed. However, commercialized capsule-type endoscopes move passively by peristaltic waves (and the gravity), which has limitation for doctors to diagnose more thoroughly and actively. In order to solve this problem, a locomotive mechanism is proposed for wireless capsule-type endoscopes. Based on the tests of various actuators, spring-type SMA actuators are selected as micro actuators for capsule endoscopes. Thus, two-way linear actuators using a pair of SMA springs are developed based on a static analysis on them. Moreover, a simple and effective clamping device is developed based on bio-mimetic approach. A prototype endoscope with four pairs of SMA springs and four clampers was developed. It has 13 mm in diameter and 33mm in total length, with a hollow space of 7.6 mm in diameter to comprise endoscope components such as a camera, and communication module, sensors, and a battery. A sequential control of the four actuation modules improves the efficiency of locomotion up to four times. For feasibility test of proposed locomotive mechanism, a series of experiments were carried out including in-vitro tests. Based on results of the experiments, we conclude that the proposed locomotive mechanism is effective to be used for micro capsule-type endoscopes.

2008 2nd IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics, 2008

Recently, coronary artery disease such as angina pectoris and myocardial infarction has become th... more Recently, coronary artery disease such as angina pectoris and myocardial infarction has become the major causes of death. As a method of medical treatment for the disease, the pharmacological approaches and the surgical operations are executed. Especially, percutaneous coronary intervention (PCI) using catheters are the mostly preferred treatment for coronary artery diseases. The PCI technologies are advanced and the various useful devices are developed and utilized. However, some clinical operations such as the treatment of chronic total occlusion (CTO) remain a limitation of PCI and a major challenge. As robot-assisted coronary interventions, this paper proposes the microrobot for the therapy of CTO. The microrobot consists of the functions of position recognition, locomotion and treatment in the blood vessels. The innovative technologies and surgical concept using the microrobot are currently being developed.

Journal of Applied Polymer Science, 2010

The conducting polymer composite material is desired to have a high dielectric constant and high ... more The conducting polymer composite material is desired to have a high dielectric constant and high dissipation factor in low and high frequency ranges, so that it can be used in charge storing devices, decoupling capacitors, and electromagnetic interference (EMI) shielding applications. Currently, on-going research is trying to enhance the dielectric constant of ceramic powder-polymer, metal powder-polymer, and nanotube-polymer composites in the low frequency region. In this article, we present the dielectric properties of polypropylene (PP)-graphite (Gr) composites in low and radio frequency ranges. Furthermore, the EMI shielding properties of these composites are examined in the radio frequency range. The PP-Gr composites were prepared by mixing and the hot compression mold technique. The electrical conductivity and dielectric constant of PP-Gr composites with graphite volume fraction follow the power law model of percolation theory. The percolation threshold of the composites is estimated to be 0.0257 ($ 5wt % of Gr). The current of PP-Gr composites as a function of voltage shows a nearly ohmic behavior above the percolation threshold. Shore-D hardness of the composites is decreased with the addition of conducting filler. The PP-Gr composites exhibit a high dielectric constant and high dissipation factor with the addition of graphite in low frequency and radio frequency regions, so they can be used in the proposed applications.

Diseases in the gastro-intestinal tract are on an increasing trend. In order to diagnose a patien... more Diseases in the gastro-intestinal tract are on an increasing trend. In order to diagnose a patient, various signals of the digestive organ, such as temperature, pH, and pressure, can offer the helpful information. Among the above mentioned signals, we choose the pressure variation as a monitoring signal. The variation of a pressure signal of the gastro-intestinal tract can offer the information of a digestive trouble or some clues of the diseases. In this paper, a pressure monitoring system for the digestive organs of a living pig is presented. This is why a pig's gastro-intestinal tract is very similar as human's. This system concept is to transmit the measured biomedical signals from a transmitter in a living pig to a wireless receiver that is positioned out of body. The integrated solution includes the following parts: (1) the swallow type pressure capsule, (2) the receiving set consisting of a receiver, decoder box, and PC. The merit of the proposed system is that the monitoring system can supply the precise and repeatable pressure in the gastro-intestinal tract. In addition, the design of low power consumption enables it to keep sending reliable signals while the pressure capsule is working in the digestive organ. The subject of the study for the pressure monitoring system is in-vivo experiments for a living pig. We achieved the pressure tracings in digestive organs and verified the validity of system after several invivo tests using the pressure monitoring system. As a result, we found each organ has its own characterized pressure fluctuation.

We propose a new electromagnetic actuation (EMA) system for an intravascular microrobot with stee... more We propose a new electromagnetic actuation (EMA) system for an intravascular microrobot with steering, locomotion and drilling functions. The EMA system consists of 3 pairs of Helmholtz coil and 1 pair of Maxwell coil. Generally, Helmholtz coils can align a microrobot in a desired direction by generating a uniform magnetic flux. If the uniform magnetic field generated by Helmholtz coils can be rotated, a microrobot with Helmholtz coils can also be rotated. On the other hand, a Maxwell coil, which generates a constant gradient magnetic flux, can supply the propulsion force for the microrobot. A microrobot actuated by the proposed EMA system has a spiral shaped body containing two magnets with different magnetization directions. With the proposed EMA system, the microrobot can move to the target region and perform drilling there by the precessional magnetic field of the Helmholtz coil pairs. The propulsion force for the microrobot is produced by the gradient magnetic field generated by the Maxwell coil pair. The moving velocity and the drilling performance of the microrobot can be increased by the propulsion force of the Maxwell coil pair. Through various tests, the feasibility and enhancement of the microrobot actuated by the proposed EMA system were verified.

Transactions of the Korean Society of Mechanical Engineers A

A treatment system for Korea Heavy Ion Medical Accelerator (KHIMA) project has more restricted be... more A treatment system for Korea Heavy Ion Medical Accelerator (KHIMA) project has more restricted beam irradiation range than other treatment systems that use the rotating gantry mechanisms since its beam direction is fixed. Therefore, in order to extend the range of beam irradiation, a 6-DOF robotic patient positioning system (PPS) is necessary. In this paper, we explain a design approach for the 6-DOF robotic PPS suitable for KHIMA project.

Recently, there have been efforts to develop bone fracture reduction robotic systems to relieve t... more Recently, there have been efforts to develop bone fracture reduction robotic systems to relieve the surgeons' physical load and X-ray exposure. In this paper, an interactive mode control scheme is proposed where a surgeon manipulates a positioning robot directly by applying force at a knob on a 6-axis Force/Torque sensor attached on a so-called positioning robot. The positioning robot supports and/or moves the distal fracture relative to the proximal fracture that is attached to the bed. However, F/T sensor noise, the knob's gravity and the extra torque caused by the offset force deteriorate the robot's maneuverability in the interactive mode control. In this work, the gravity force compensation method is introduced. These two schemes improved the maneuverability of interactive mode control for the positioning robotic system.

The Journal of Rheumatology

As a service robot, we proposed a flower robot which has several functions, such as motion mechan... more As a service robot, we proposed a flower robot which has several functions, such as motion mechanism, sensing ability, and home appliance functions. Among the various functions of flower robot, the motion mechanism is very important function because flower robot should describe their emotion by making gesture. Flower robot can be divided as a flower, a stem and leaves. In previous research, we already proposed stem mechanism actuated by tendons and motors. But this previous stem mechanism has two kinds of drawbacks. Firstly, the previous stem structure has a limited bending angle only about 10 degrees and thus it has the restricted view-angel. Secondly, the stem structure has only two degree of freedom bending motion and it cannot describe various motions. Therefore, we need more advanced stem mechanism which has more degree of freedom in order for the flower robot to express various motions of the flower robot. The new stem mechanism has totally five degree of freedom. Two degrees ...

This paper deals with a study and development of the flower robot among service robots, which has... more This paper deals with a study and development of the flower robot among service robots, which has the functions of interior and robotic movements. The proposed flower robot consists of flower, stem and leaves, which are actuated by the tendon mechanism. The flower, stem and leaves structures are integrated and controlled as one flower robot. For the control, we used dSPACE system and Simulink of MATLAB. From the development of the flower robot, we mimic the blooming of the flower, the swaying of the stem, and the stirring of the leaves, respectively, and can fabricate the sensor integrated robotic flower robot.

As a service robot, we proposed a flower robot which has several functions, such as moving mechan... more As a service robot, we proposed a flower robot which has several functions, such as moving mechanism, sensing ability, and home appliance functions. Among the various functions, the moving function of the flower robot is very important function. The moving flower robot can be divided as a flower, a stem and leaves. We tried to mimic the blooming of flower, the swaying of the stem and the stirring of the leaves in the wind. For the actuation of the flower robot, we used micromotors and tendon mechanisms. From the motions of the flower, the stem and the leaves, the desired target positions are decided. In addition, based on inverse kinematics and trajectory generations, the overall control system for the moving flower robot is constructed. Through the various experiments, the performances of each part of the flower robot are verified and the characteristics are discussed.