• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.531-537
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• 2009

When creating large crowds, it is unavoidable that the models and motions of many characters will be cloned. McDonnell implemented experiments focus on appearance and motion of characters to test user perception of crowds. As a result, appearance clones were easier to perceive than motion clones. In this paper, I researched about relation between character cloning and user perception for real-time game environment expanding McDonnell's research. This paper focuses on the way to recognition of multiple clones in dramatic environment free to change view point and has crowds move to every directions by trajectories. In particular, this paper shows the possibility of character diversification applied various shapes, colors and patterns to game item have important elements for game characters. Also, I suggests range of distances between clones by a series of experiments of user perception for clones's moving direction and distance.

• Journal of Korean Foot and Ankle Society
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• v.13 no.2
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• pp.133-137
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• 2009

Purpose: The purpose of this study was to evaluate the clinical results of the old Achilles tendon rupture treated with modified flexor hallucis longus (FHL) tendon transfer. Materials and Methods: Seventeen patients with old Achilles tendon rupture treated with modified FHL tendon transfer between March 2004 and February 2008 were enrolled in this study. Technically FHL was pass through the distal portion of the ruptured tendon instead of the drilled hole made on the calcaneus. The mean age of the patients was 37 years (range, 22~67 years), mean follow-up period was 28 months (range, 12~30 months). Patients' subjective satisfaction, calf circumferential diameter, range of motion of ankle and AOFAS ankle-hind foot score and Arner-Lidholm score was evaluated. Results: The average gap between the ruptured tendon was 52 mm (range, 47~56 mm). The AOFAS score improved from 47 pre-operatively to 91 points at the last follow-up. Sixteen patients were satisfied with the result free from discomfort, a patient had mild discomfort who had DM. fourteen patients had decreased range of motion less than 5 degrees while 2 patients had more than 7 degrees decrease compared to the intact side but had no discomfort in daily activities. Nine patients had less than 1 cm calf circumferential diameter difference and 7 patients had 1 to 3 cm diameter difference compared to the intact side. One who had more than 3 cm diameter difference had deteriorated muscle strength. Conclusion: Modified FHL tendon transfer can be a useful technique for the treatment of old Achilles tendon rupture when the gap is with large gap placed too proximal.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1499-1507
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• 2017

This paper presents an impact-based piezoelectric vibration energy harvester using a freely movable metal sphere and a piezoceramic fiber-based MFC (Macro Fiber Composite) as piezoelectric cantilever. The free motion of the metal sphere, which impacts both ends of the cavity in an aluminum housing, generates power across a cantilever-type MFC beam in response to low frequency vibration such as human-body-induced motion. Impacting force of the spherical proof mass is transformed into the vibration of the piezoelectric cantilever indirectly via the aluminum housing. A proof-of-concept energy harvesting device has been fabricated and tested. Effect of the indirect impact-based system has been tested and compared with the direct impact-based counterpart. Maximum peak-to-peak open circuit voltage of 39.8V and average power of $598.9{\mu}W$ have been obtained at 3g acceleration at 18Hz. Long-term reliability of the fabricated device has been verified by cyclic testing. For the improvement of output performance and reliability, various devices have been tested and compared. Using device fabricated with anodized aluminum housing, maximum peak-to-peak open-circuit voltage of 34.4V and average power of $372.8{\mu}W$ have been obtained at 3g excitation at 20Hz. In terms of reliability, housing with 0.5mm-thick steel plate and anodized aluminum gave improved results with reduced power reduction during initial phase of the cyclic testing.

• Archives of Plastic Surgery
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• v.39 no.2
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• pp.138-142
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• 2012

Background : Electrical burns are one of the most devastating types of injuries, and can be characterized by the conduction of electric current through the deeper soft tissue such as vessels, nerves, muscles, and bones. For that reason, the extent of an electric burn is very frequently underestimated on initial impression. Methods : From July 1999 to June 2006, we performed 15 cases of toe tissue transfer for the reconstruction of finger defects caused by electrical burns. We performed preoperative range of motion exercise, early excision, and coverage of the digital defect with toe tissue transfer. Results : We obtained satisfactory results in both functional and aesthetic aspects in all 15 cases without specific complications. Static two-point discrimination results in the transferred toe cases ranged from 8 to 11 mm, with an average of 9.5 mm. The mean range of motion of the transferred toe was $20^{\circ}$ to $36^{\circ}$ in the distal interphalangeal joint, $16^{\circ}$ to $45^{\circ}$ in the proximal interphalangeal joint, and $15^{\circ}$ to $35^{\circ}$ in the metacarpophalangeal joint. All of the patients were relatively satisfied with the function and appearance of their new digits. Conclusions : The strategic management of electrical injury to the hands can be both challenging and complex. Because the optimal surgical method is free tissue transfer, maintenance of vascular integrity among various physiological changes works as a determining factor for the postoperative outcome following the reconstruction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.859-865
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• 2007

This paper presents a method to analyze the unbalance response of a high speed polygon mirror scanner motor supported by sintered bearing and flexible supporting structures by using the finite element method and the mode superposition method. The appropriate finite element equations for polygon mirror are described by rotating annular sector element using Kirchhoff plate theory and von Karman non-linear strain, and its rigid body motion is also considered. The rotating components except for the polygon mirror are modeled by Timoshenko beam element including the gyroscopic effect. The flexible supporting structures are modeled by using a 4-node tetrahedron element and 4-node shell element with rotational degrees of freedom. Finite element equations of each component of the polygon mirror scanner motor and the flexible supporting structures are consistently derived by satisfying the geometric compatibility in the internal boundary between each component. The rigid link constraints are also imposed at the interface area between sleeve and sintered bearing to describe the physical motion at this interface. A global matrix equation obtained by assembling the finite element equations of each substructure is transformed to a state-space matrix-vector equation, and both damped natural frequencies and modal damping ratios are calculated by solving the associated eigenvalue problem by using the restarted Arnoldi iteration method. Unbalance responses in time and frequency domain are performed by superposing the eigenvalues and eigenvectors from the free vibration analysis. The validity of the proposed method is verified by comparing the simulated unbalance response with the experimental results. This research also shows that the flexibility of supporting structures plays an important role in determining the unbalance response of the polygon mirror scanner motor.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.217-224
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• 2014

We have developed the novel device that can extract energy from ocean waves utilizing the heaving motion of a floating mass. The major components of the energy converter are: a floater, a counterweight, a cable, a driving pulley, two idler pulleys, a ratchet, and a generator. The device generates power through the tension force in the cable and the weight difference between the floater and the counterweight. When the system is at static free condition, the tension in the cable is equal to the weight of the counterweight which is minimum. Therefore it is desirable to keep the counterweight lighter than the floater. However, experiments show that during the rise of the water level, the torque generated by weight of the counterweight is insufficient to rotate the driving pulley which causes the cable on the floater side to slack. The proposed application of the tension pulley rectifies these problems by preventing the cable from becoming slack when the water level rises. In this paper, the dynamics model is modified to incorporate the dynamics of the tension pulley. This has been achieved by first writing the dynamical equations for the tension pulley and the energy converter separately and combining them later. This paper investigates numerically the effect of the tension pulley on various physical quantities such as the cable tension, the floater displacement, and the floater velocity. Results obtained indicate that this application is successful in suppressing large fluctuations of the cable tension.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.7
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• pp.665-670
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• 2010

The effect of a particle's spin is investigated numerically by taking into account the effect of lift forces originating due to difference between the rotations of a particle and of a fluid, such as the Saffman and Magnus lift forces. These lift forces have been ignored in many previous studies on particle-laden turbulence. The trajectory of the particles can be changed by the lift forces, resulting in a significant modification of the stochastic characteristics of heavy particles. Probability density functions and autocorrelations are evaluated from the velocity of solid particle, acceleration of solid particles, and acceleration of fluid at the position of solid particle. Changes in velocity statistics are negligible but statistics related with acceleration are affected by the rotation of particle. When a laden particle encounters coherent structures during its motion, the particle's rotation might significantly affects the motion due to intermittently large fluid acceleration near the coherent structures.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.816-824
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• 2010

The forces applying to an object in the transferring pipe of waste are analyzed and the equation of motion is established in this paper. It is shown that the equation of motion becomes the 1st order non-linear differential equation. Using its general solution, the velocity of the object in the transferring pipe of waste can be expressed in the explicit form. Noting that the velocity of object is impact velocity to the elbow or curved part of the transferring pipe of waste, the kinetic energy of the object can be calculated and the necessary impact strength of inner wall is obtained. The velocity of object is also calculated and presented in the graphic forms with the condition of air velocity 30m/sec. The impact test of cast basalt tube is carried out by the free fall of a weight and the test results show that the impact strength of the cast basalt tube is sufficient to apply to protecting inner wall of the transferring pipe of waste.

• Investigative Magnetic Resonance Imaging
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• v.21 no.1
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• pp.20-27
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• 2017

Purpose: To evaluate quantification results of single breath-hold (SBH) magnetic resonance (MR) cine imaging compared to results of conventional multiple breath-hold (MBH) technique for left ventricular (LV) function in patients with cardiac arrhythmia. Materials and Methods: MR images of patients with arrhythmia who underwent MBH and SBH cine imaging at the same time on a 1.5T MR scanner were retrospectively reviewed. Both SBH and MBH cine imaging were performed with balanced steady state free precession. SBH scans were acquired using temporal parallel acquisition technique (TPAT). Fifty patients ($65.4{\pm}12.3years$, 72% men) were included. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), myocardial mass, and LV regional wall motion were evaluated. Results: EF, myocardial mass, and regional wall motion were not significantly different between SBH and MBH acquisition techniques (all P-values > 0.05). EDV, ESV, and SV were significant difference between the two techniques. These parameters for SBH cine imaging with TPAT tended to lower than those in MBH. EF and myocardial mass of SBH cine imaging with TPAT showed good correlation with values of MBH cine imaging in Passing-Bablok regression charts and Bland-Altman plots. However, SBH imaging required significantly shorter acquisition time than MBH cine imaging ($15{\pm}7sec$ vs. $293{\pm}104sec$, P < 0.001). Conclusion: SBH cine imaging with TPAT permits shorter acquisition time with assessment results of global and regional LV function comparable to those with MBH cine imaging in patients with arrhythmia.

• Journal of Chest Surgery
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• v.21 no.1
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• pp.70-81
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• 1988

From January 1962 to March 1987, 97 patients underwent operation for mitral valve disease. Of these patients, 61 [62.9%] required mitral valve replacement. Thirty-six patients [37.1%] had mitral valve repair. The mean age was 26.9*11.6 years [range 5 months to 48 years]. There were 32 [88.9%] cases of rheumatic valve disease, 4 [11.1%] cases of congenital mitral valve disease. Valve dysfunction was classified into three types: type I [normal leaflet motion], 6 patients; type II [prolapsed leaflet], 1 patient; type III [restricted leaflet motion], 29 patients. Twenty-nine patients [80.6%] had pure or predominant stenosis and 7[19.4%] had pure regurgitation. No patient was in NYHA functional class I. Three patients [16.7%] were in functional class II, 15[83.3%] were in functional class II. The techniques used included closed mitral commissurotomy [16 patients], open mitral commissurotomy [13 patients], localized Wooler type annuloplasty [4 patients], suture repair of leaflet defect [3 patients], chordal shortening [1 patient], Carpentier ring annuloplasty [1 patient], and fenestration of fused chordae [1 patient]. There were two perioperative deaths [5.6%], related to left ventricular failure and reoperation. The survivors were followed up for 94 patient-years [mean 4.68*5.54 years]. One late death [1.1*1.1% per patient-year] occurred and was valve related. Reoperation was required in 3 patients, of whom 2 were deaths. There was 1 case [1.1*1.1% per patient-year] of thromboembolism. No patient received anticoagulant after operation. At 10 year, 92*7.4% of the patients were still alive. The actuarial survival rate of patients free of valve-related complication was 79*6.4% at 6 years, 27*12.1% at 11 years. After surgery, 18 patients [88.9%] were in NYHA functional class I or II.