• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.142-143
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• 2008

In the present work, high-speed video images of the ground take-off flight of a live butterfly were captured and their dynamic motions during the first full-stroke were analyzed. To capture the dynamic images of the take-off motion, the experimental setup consisted of a high-speed camera, a Xenon lamp as a light source and a transparent chamber of $15^W{\times}15^L{\times}17^H$ $cm^3$ in physical size. The ambient temperature and supplementary lighting devices were precisely controlled. The weight and wing span of the butterfly tested in this study was 104 mg and 63.14 mm, respectively. The ground take-off images were captured with 4000 fps with a spatial resolution of (1024${\times}$512) pixels. The period of the first full-stroke was 80.5ms and the flapping speed of downstroke was 2 times faster than that of upstroke. As a result, butterflies used the fling and near-clap motion to generate lifting force and an interesting take-off behavior of early pronation and downstroke was observed.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.538-544
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• 2009

As the world game marcket has been recording weak growth, the development of new gane concept is required to attract the gamer's attention from those who were fed up with the previous game paradigm. Recently, the game which can recognize the player's motions and provide new interaction between the game and user is more popular than ever before. In the games with somesthesia based on Virtual Reality, the sense of the reality is considered the most important factor for drawing immersion from the gamers. In this work, a new type of 3-axis accelerometer based interactive game interface which can effectively recognize the gamer' motion is suggested. Furthermore, various experiments are carried out to verify the effectiveness of the proposed scheme.

• The Journal of Korean Physical Therapy
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• v.24 no.3
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• pp.235-239
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• 2012

Purpose: To recognize the change in the proprioception under conditions that activate the local muscles, this study found the difference in the proprioception on a fixed and swing chair. Methods: Healthy adults (7 males, 13 females) in their twenties were evaluated lumbar position sense on fixed and swing chair. And the difference of the position sense between the fixed and swing chair were analyzed. Results: The joint position senses were compared between the fixed and swing chair. As a result, there was a significant difference from all motions. Conclusion: This study found that the improvement of proprioception using swing chair means that the local muscle is activated. Therefore, to use a swing chair, which was designed in this study, is able to replace the general chair either at work or during studies. Thus, this method is easily accessible for busy modern people who are exposed to low back pain or spinal disorders due to a pattern of inactivity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.177-178
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• 2014

This work proposes a two-dimensional (2-D) laser scanning mirror actuator with a simple structure composed of one magnet and four coils. The mirror-actuating device generates 2-D scanning motions about two orthogonal axes by combining electromagnetic actuators of the conventional moving-magnet types. The magnet is attached to back side of the mirror placed inside of the moving frame. The four coils is placed on the base frame in a cross shape. We implement a finite element analysis to calculate magnetic flux in the electromagnetic system with the overall size of $20mm(W){\times}20mm(D){\times}13mm(H)$ for the mirror size of $8mm{\times}8mm$. The each moving-magnet type electromagnetic actuator has the motor constant 3.41 mNm/A and the restoring constant 1.75 mNm/rad and the resonance frequency of 58 Hz and the bandwidth of 80 Hz. The proposed compact and simple 2-D scanning mirror predicted advantages of large 2-D angular deflections, wide frequency bandwidth and low manufacturing cost.

• The Journal of Korea Robotics Society
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• v.6 no.3
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• pp.220-229
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• 2011

This paper focuses on a development of an anthropomorphic robot hand. Human hand is able to dexterously grasp and manipulate various objects with not accurate and sufficient, but inaccurate and scarce information of target objects. In order to realize the ability of human hand, we develop a robot hand and introduce a control scheme for stable grasping by using only kinematic information. The developed anthropomorphic robot hand, KITECH Hand, has one thumb and three fingers. Each of them has 4 DOF and a soft hemispherical finger tip for flexible opposition and rolling on object surfaces. In addition to a thumb and finger, it has a palm module composed the non-slip pad to prevent slip phenomena between the object and palm. The introduced control scheme is a quitely simple based on the principle of virtual work, which consists of transposed Jacobian, joint angular position, and velocity obtained by joint angle measurements. During interaction between the robot hand and an object, the developed robot hand shows compliant grasping motions by the back-drivable characteristics of equipped actuator modules. To validate the feasibility of the developed robot hand and introduced control scheme, collective experiments are carried out with the developed robot hand, KITECH Hand.

• Proceedings of the Safety Management and Science Conference
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• 2011.11a
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• pp.573-582
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• 2011

This study has three objectives; 1) Evaluate major jobs of hospital workers based on Criterion(Notification number 2003-24 from Ministry of Labor in Korea) for high-risk job for musculoskeletal disorders(MSDs), 2) Relate each jobs in criterion and the hospital jobs considered in this study, 3) Relate each jobs in criterion and MSDs symptoms of hospital workers. A total 141 hospital jobs was evaluated. Most hospital jobs belonged to the numbers 2(Job with repetitive motions by neck, shoulder, elbow, wrist or hand more than 2 hours a day) and 4(Job with unsupported and deviated postures by neck or back more than 2 hours a day) from criterion. Most hospital workers participated in this study thought that the numbers 1(Job with keyboard or mouse work more than 4 hours a day) and 2 from criterion were associated with their jobs. Further study for hospital jobs should be focused on breaking down quantification levels of each numbers in the criterion due to its atypical and non-repetitive job characteristics of hospital jobs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1182-1187
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• 2004

Robust, real-time, fully automatic tracking of facial features is required for many computer vision and graphics applications. In this paper, we describe a fully automatic system that tracks eyes and eyebrows in real time. The pupils are tracked using the red eye effect by an infrared sensitive camera equipped with infrared LEDs. Templates are used to parameterize the facial features. For each new frame, the pupil coordinates are used to extract cropped images of eyes and eyebrows. The template parameters are recovered by PCA analysis on these extracted images using a PCA basis, which was constructed during the training phase with some example images. The system runs at 30 fps and requires no manual initialization or calibration. The system is shown to work well on sequences with considerable head motions and occlusions.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.17-25
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• 2009

This study was aimed to analyze of characteristics of Musculoskeletal disorders (MSDs) based on the industrial accident statistics which were extracted from the Ministry of Labor. In this study all MSDs cases in 2007, 7,723 cases, were investigated. First of all, for the analysis of a wide view point concerning the characteristics of MSDs, We have inspected characteristics of the user population (i.e. age, gender, employed periods, etc.). Secondly, work-related risk factors such as repetitive motions, awkward postures, manual material handling were analyzed in terms of disease code, injured part of body, types of business, etc. Next, characteristics of handling of heavy materials were analyzed according to weight, types of handling, agency of cause, etc. Finally, we have compared and analyzed the features between the period of hospitalization and other variables. In addition to that we also conducted statistics analysis. The study results showed that there were significant characteristics of MSDs that could be used as basis data for the MSDs prevention policy.

• Composites Research
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• v.33 no.2
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• pp.50-54
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• 2020

Soft robotics and wearable devices require large motions and flexibility. In this regard, there is a demand for developing stretchable strain sensors which can be attached to the soft robots and wearable devices. In this work, we fabricated stretchable and electrically conductive composite fibers by combining polyurethane (PU) and silver nanoflowers (AgNFs). The PU/AgNF composite fibers showed the change of the resistance as a function of the applied strain, demonstrating the potential for stretchable strain sensors in soft robotics and wearable devices. The mechanical and electrical characteristics of the composite fibers were measured and analyzed to use the composite fibers for stretchable strain sensors.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.111-124
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• 2011

The objective of this study is to develop the blind control strategy and method which reduce negative effect of incoming daylight on visual comfort of occupants, minimize psychological anxieties caused by frequent motions of a blind, and maximize positive effect of incoming daylight by opening/closing of a blind. In previous researches on blind controls, major problem is that the time interval and amount of blind movement do not meet the control objective at the inflected zone of solar profile curve. To overcome these limitations revealed in theprevious researches, following tasks were performed in this study. i)To establish the control objective to accomplish the goal of this study. ii)To develop the control methods and algorithms which prevent glare on the work-plane at any time and which control the time interval and amount of blind movement to follow the control objective at various solar profile angle curves. This study proposed the control strategy and method that define the base control section implying the inflection point within the control objective zone and subsequently, divide the control sections for the residual time zones. The proposed strategy and method are found to increase the incoming daylight and solar irradiation by 0 to 15 %.