• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.136-142
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• 2008

The influence of different grids on numerical prediction of subsonic compressor performance and stall was investigated. Two types of grids were examined, structured H type grid and structured O-H type grid. Evaluations were conducted by comparing the numerical results with experimental results obtained from a low-speed single-stage rig test for a new concept compressor, called diffuser passage compressor, aiming at improving tip clearance sensitivity. At low mass flow operating conditions, the numerical calculation with O-H type grid showed that the lowest mass flow operating point for which the calculation was able to converge was almost the same as the lowest steady mass flow obtained from the rig test. On the other hand, the numerical calculation with structured H type grid diverged at higher mass flow operating point. It was found that this difference was attributed to the effect of double-valuedness of H type grid that existed at leading edge on the boundary layer development on the blade surface.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2102-2104
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• 2004

In this study, sheathless electrospray from PDMS/glass microchips with conducting metal emitter tip is described. A chip-based capillary electrophoresis/mass spectrometry (CE/MS) system has advantages of the CE separation and on-line electrospray detection of peptide solution. We have fabricated a new electrospray ionization(ESI) device composed of the metal emitter tip and CE separation channel monolithically in a glass microchip. The separation channel and metal emitter tip are fabricated using a glass wet etching and gold electro plating process, respectively. The fabricated micro electrospray chip was tested by spraying peptide sample for mass spectrometric analysis. Singlely-charged peak and doublely-charged peak of peptide were detected and further MS/MS fragmentation was performed in each peak. Direct comparisons with conventional glass or fused silica emitters showed very similar performance with respect to signal strength and stability.

• Korean Journal of Head & Neck Oncology
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• v.36 no.2
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• pp.33-36
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• 2020

Cutaneous horn is the clinical entity, which is circumscribed, conical, markedly hyperkeratotic lesion in which the height of the keratotic mass amounts to at least half of its largest diameter. It may be associated with many different pathological lesions. It is a relatively rare and a kind of epidermal tumor that generally appears as a conical projection. Here, we report rare case of congenital cutaneous horn. A 39-month-old female Korean patient presented at our clinic with a mass at the tip of her nose present since birth. Under general anesthesia, cutaneous horn of nasal tip was completely excised without any complications. The operation site was small enough to perform a primary closure, without any nasal deformity. Histopathologically, it was reported as a fibroepithelial polyps. After operation, there is no evidence of recurrence at 16 months of follow-up.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.10
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• pp.645-651
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• 2016

Effects of pressure-side winglet width on the tip leakage flow and aerodynamic loss downstream of a turbine blade with a pressure-side squealer rim have been investigated for the tip gap-to-span ratio of h/s = 1.36%. The pressure-side squealer has a fixed height-to-span ratio of $h_p/s=3.75%$ and the pressure-side winglet, which is installed at an elevation of tip surface, has width-to-pitch ratios of w/p = 2.64%, 5.28%, 7.92% and 10.55%. The results show that with increasing w/p, aerodynamic loss in the passage vortex region decreases, whereas that in the leakage flow region increases. As a result, the mass-averaged loss coefficient all over the measurement plane tends to decrease minutely with the increment of w/p. It is concluded that the pressure-side winglet for the pressure-side squealer tip can hardly contribute to the tip-leakge loss reduction.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.577-582
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• 1989

This is a study of the translational end-point control of a single link flexible arm-with a tip mass. The beam is mounted on a translational mechanism driven by the ball screw, whose rotation is controlled by DC servomotor. The problem of shifting the end-point from its initial position to the commanded position is studied analytically both for the open-loop control subjected to some path functions and for the closed-loop control using the feedback of the tip information.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.290-303
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• 2017

This paper aims to build a drone platform based on an optimum design of its single arm. We assumed its single arm as a cantilevered beam with a tip mass. Based on the numerical optimization theory, we conducted validation and optimization of a new design by comparing the results with the similar ones obtained by ANSYS. Finally, this design is reflected in the control simulation, and the requirement of an optimum structural design considering the resonance situation is demonstrated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.5
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• pp.453-459
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• 2010

In this paper, the purpose is to investigate the stability of cracked cantilever T-beams subjected to axial force. In addition, an analysis of the natural frequency of a cracked beams as crack position, crack depth and tip mass is investigated. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by the energy expressions using extended Hamilton's Principle. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. The results of this study will contribute to the safety test and stability estimation of structures of a cracked T-beams subjected to axial force.

• Journal of KSNVE
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• v.5 no.3
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• pp.385-394
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• 1995

Recently, since robot manipulator becomes faster and lighter, its link is no longer regarded as rigid body, and robot controller which only controls robot position cannot reduce vibration of the flexible link. Therefore vibration control is needed in robot manipulator control in addition to position control. In the case that tip mass changes when robot manipulator in working, it is clear that the efficiency of the vibration/position controller designed for the fixed system goes down. In this paper, the system with time varying parameters, adaptive control theory is adopted which estimates parameters changed by the variation of the tip mass and re-calculates the gain of the controller. Validify of the proposed adaptive controller and capability of the estimator are evaluated by computer simulations and experiments. Comparison results of the optimal controller for the fixed system and proposed adaptive controller and carried out.

• Journal of Korean Neurosurgical Society
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• v.51 no.1
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• pp.62-65
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• 2012

Despite the remarkable developments in neurosurgical and neuro-interventional procedures, the optimal treatment for large or giant partially thrombosed aneurysms with a mass effect remains controversial. The authors report a case of a partially thrombosed aneurysm with a mass effect, which was successfully treated by stent-assisted coil embolization. A 41-year-old man presented with headache. Brain computed tomography depicted an $18{\times}18$ mm sized thrombosed aneurysm in the interpeducular cistern. More than 80% of the aneurysm volume was filled with thrombus and the canalized portion beyond its neck measured $6.8{\times}5.6$ mm by diagnostic cerebral angiography. Stent-assisted endovascular coiling was performed on the canalized sac and the aneurysm was completely obliterated. Furthermore, most of the thrombosed aneurysm disappeared in the interpeduncular cistern was clearly visualized follow-up brain magnetic resonance imaging conducted at 21 months. The authors report a case of selective coiling of a large, partially thrombosed basilar tip aneurysm.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.65-75
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• 2001

Modern vehicles require a high degree of refinement including good driveability. Vehicle driveability, which becomes a key decisive factor f3r marketability, is affected by many parameters such as engine control and the dynamic characteristics in drive lines. Therefore engine and drive train characteristics should be considered to achieve a well balanced vehicle response simultaneously. This paper describes experimental procedures which have been developed to measure engine torque and investigate shuffle characteristics. To analyze the vehicle dynamic behavior, fractional torques and inertia mass moment of engine, and drive train were measured. Shuffle characteristics during tip-in condition were investigated in an experimental vehicle at 2nd and 3rd gear stages. It was found that the shuffle characteristics were caused by sudden changes of engine torque and have a different vibration frequency with gear stage variation. Inertia mass moment of engine including flywheel rotation showed a key factor for the shuffle characteristics.