• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.289-294
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• 2010

Numerical stud of an oscillating body in incompressible fluid is performed. Stabilized finite element method comprising of Streamline-Upwind/Petrov-Galerkin (SUPG) and Pressure-Stabilizing/Petrov-Galerkin (PSPG) formulations of linear triangular elements was employed to solve 2D incompressible Navier-Stokes equations whereas the motion of the body was considered by incorporating the arbitrary Langrangian-Eulerian(ALE) formulation. An algebraic moving mesh strategy is utilized for obtaining body conforming mesh deformation at each time step. Two tests cases, namely motion of a circular cylinder and of an airfoil in incompressible flow were analyzed. The model is first validated against the stationary cases and then the capability to handle moving boundaries is demonstrated.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.5 s.149
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• pp.538-549
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• 2006

A code is developed to simulate a viscous flow field around a deformable body using the hybrid Cartesian/immersed boundary method. In this method, the immersed boundary(IB) nodes are defined near the body boundary then velocities at the IB nodes are reconstructed based on the interpolation along the normal direction to the body surface. A new method is suggested to define the IB nodes so that a closed fluid domain is guaranteed by a set of IB nodes and the method is applicable to a zero-thickness body such as a sail. To validate the developed code, the vorticity fields are compared with other recent calculations where a cylinder orbits and moves into its own wake. It is shown the code can handle a sharp trailing edge at Reynolds number of $10^5$ under moderate requirements on girds. Finally the developed code is applied to simulate the vortex shedding behind a deforming foil with flapping tail like a fish. It is shown that the acceleration of fluids near the flapping tail contributes to the generation of the thrust for propulsion.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.136-137
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• 2002

We have been researching upgrade version of a stereotactic whole body frame, used for evaluating daily setup accuracy of the patient positioning during fractionated extra-cranial stereotactic radiotherapy. Currently, we are focusing on the development of a new stereotactic whole body frame, and then will handle organ movement produced by breathing at the next stage. MeV-Green is chosen for the best immobilizer possible and the epoxy board is for the frame with the dimension of 110 em in length, 50 cm in width in order to maximize transmission rate of the beam from lateral or posterior direction and to fit CT and PET scanners with an aperture of 55 cm at least. The key point of an upgraded stereotactic whole body frame will be set on the collision-free rotation of the gantry with the frame, and the development of the checking structure for the daily patient repositioning regarding internal target.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2555-2560
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• 1996

Inspecting the dimensional accuracy of a car-body in assembly line is a very important process to assure high productivity. Now there exist two common inspecting methods in practice. One is to measure a sampled car-body with three dimensional measuring machine, and the other is to measure car-body with three dimensional measuring machine, and the other is to measure car-body in assembly line using many sensors fixed to a large jig frame. The formal method takes too long to inspect a sampled car-body of a same sort, and cannot therefore give an useful error trend for the whole production. On the other hand, the latter lacks flexibility and is very cost-intensive. By using industrial robots and sensors, an in-line Car-Body Measuring(CBM) system which ensured high flexiblity and sufficient accuracy was developed. This CBM cell operates in real production line and measures the check points by the non-contact type using camera and laser displacement sensor(LDS). This system can handle about 15 Measuring points within a cycle time of 40 seconds. A process computer controls whole process such as data acquisition file handling and data analysis. Robot arms changes in length due to ambient temperature fluctuation affecting the measuring accuracy. To compensate this error, a robot arm calibration process was developed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.24-30
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• 2021

In this study, an augmented reality (AR) app that detects the screw-assembly state of a car valve-body and assists the assembly work is developed and the effectiveness of the app is shown through testing. The app creates the contents indicating the screw-assembly position and order, and the screw-assembly state. Then, the contents are registrated onto the valve-body image on a smart-phone screen to be shown to the worker during assembly. To this end, the features are extracted from the 2D image of the valve-body and the location of the valve-body is tracked. By extracting the areas where the screws are to be assembled, and periodically determining the luminance of these areas, it is checked whether the screws are assembled in order at the predetermined position of the valve-body. When an error is detected during assembly, a warning sound is notified to the worker, and the worker can check the assembly state on the smart-phone screen and handle the error, immediately. Study results found that it takes about 65 ms to detect the assembly state of the five screws, and the assembly state is detected without error for 1 hour.

• Phonetics and Speech Sciences
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• v.7 no.4
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• pp.93-99
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• 2015

In case of PAS test, the air is sometimes leaked although the mask is tightly attached to the face, which is not reliable on the measured values. Therefore, this study aimed to assist the clinical practice suggesting the test method of PAS without air leakage. In the healthy subjects with 12 males and 12 females over 19 years old, three types of tests were performed on the voicing efficiency among the protocol of PAS Model 6600. They are; first, to attach the mask tightly to the face holding the handle of PAS with the subject's two hands (Method 1); second, to attach the mask tightly to the face holding the handle of PAS with the subject's one hand and pushing the body of PAS strongly with the other hand (Method 2); and third, to attach the mask tightly to the face pushing the upper part of the mask by the tester when the subject attached the mask to his or her face holding the handle of PAS with two hands (Method 3). Upon the study analyses, the mean negative pressure, the mean phonogram, subglottic air pressure, and voicing efficiency were shown to be statistically significantly different during PAS test in males depending on the methods. (p<.05) In case of females, only the target airflow rate showed significant difference depending on the methods during PAS test. (p<.001) In conclusion, Method 2 enhanced the noise level and strength while Method 1 was likely to leak the air more compared to the other two methods in males. In case of females, Method 1 showed significant leakage of the air flow. Not to allow the air flow leakage without affecting the outcome of PAS test, it will be the most useful for the tester to push the mask to the subject's face tightly (Method 3).

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.481-491
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• 1995

Endovaginal and endorectal receiver only surface coils were designed for MR imaging (MRI) and $^1H$ MR spectroscopy (MRS) for the uterine cervix and the prostate. The shape of endovaginal coil wire was rectangular with round corner. Size of the coil wire was empirically determined for 7cm and 4cm along the long and short axis, respectively. The coil wire loop was supported by acryl handle and bent about $150^{\circ}$ at one side of the loop considering the average angle of the cervix to the vagina. We called this as a "spoon-type endovaginal coil". The wire of the endorectal coil was made of the flexible materials so that the wire loop became long elliptic shape by pushing the acryl handle into the plastic tube for the comfort of patients when the coil was inserted into the cervix. Then, the shape was maintained to be circle by popping out handle. Conventional spin echo (SE) and fast spin echo (FSE) sequences were used as 71 and 72 weighted imaging sequences, respectively. Matrix size was 128~$256{\times}256$. FOVs for surface coil and body coil were 14cm and 24cm, respectively. 3D volume localized in vivo $^1H$ MR spectroscopy of the human cervix and prostate was performed using PRESS or STEAM localization method with the following parameters . TR=3 sec, TE=135 msec for PRESS or 30 msec for STEAM, NEX=2, NS=48, Sl=2048, and SW=2500 Hz. Using home-built endovaginal and endorectal coils, excellent T1- and T2-images were obtained to visualize early cervical and prostate tumors. 3D volume localized in vivo IH MRS was useful to differentiate the cancerous tissue from the normal tissue.

• Safety and Health at Work
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• v.8 no.1
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• pp.11-18
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• 2017

The purpose of this review is to name and describe the important factors of musculoskeletal strain originating from pushing and pulling tasks such as cart handling that are commonly found in industrial contexts. A literature database search was performed using the research platform Web of Science. For a study to be included in this review differences in measured or calculated strain had to be investigated with regard to: (1) cart weight/ load; (2) handle position and design; (3) exerted forces; (4) handling task (push and pull); or (5) task experience. Thirteen studies met the inclusion criteria and proved to be of adequate methodological quality by the standards of the Alberta Heritage Foundation for Medical Research. External load or cart weight proved to be the most influential factor of strain. The ideal handle positions ranged from hip to shoulder height and were dependent on the strain factor that was focused on as well as the handling task. Furthermore, task experience and subsequently handling technique were also key to reducing strain. Workplace settings that regularly involve pushing and pulling should be checked for potential improvements with regards to lower weight of the loaded handling device, handle design, and good practice guidelines to further reduce musculoskeletal disease prevalence.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1857-1862
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• 2016

Human activity recognition using depth information is an emerging and challenging technology in computer vision due to its considerable attention by many practical applications such as smart home/office system, personal health care and 3D video games. This paper presents a novel framework of 3D human body detection, tracking and recognition from depth video sequences using spatiotemporal features and modified HMM. To detect human silhouette, raw depth data is examined to extract human silhouette by considering spatial continuity and constraints of human motion information. While, frame differentiation is used to track human movements. Features extraction mechanism consists of spatial depth shape features and temporal joints features are used to improve classification performance. Both of these features are fused together to recognize different activities using the modified hidden Markov model (M-HMM). The proposed approach is evaluated on two challenging depth video datasets. Moreover, our system has significant abilities to handle subject's body parts rotation and body parts missing which provide major contributions in human activity recognition.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1166-1172
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• 2003

The extremely strong competition among the world automobile industries has introduced the concept of PLM in the total production activities, one of whose major components is VM(Virtual Manufacturing). If the production lines are equipped with robots, the application of OLP in the virtual space is fully mature. However, in the point of the investment's and the maintenance's view, there are always some activities, which can not be automated: for example, typically the manual welding for prefixing in the automobile body shop and the material loading. Process planning for these activities, therefore, are decided mainly by experiences, which caused many repeated rework of the processes and the inconvenience of the workers, and resulted consequently in the reduction of the productivity and the safety of the workers. In this paper, the optimal dimension of the welding gun and its handle position and the optimal working path is simulated and decided by use of DELIMN/IGRIP and DELMIA/Ergo and the working area modelized in the virtual workcell of DELMIA.