• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.51-57
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• 2011

Purpose: The aim of this study is to identify clinical usefulness of Wide Beam Reconstruction (WBR) which is called Xpress.cardiac$^{TM}$ to confirm the agreement between segmental perfusion and regional wall motion in myocardium compared to conventional OSEM method. Materials and Methods: Subjects were separated two groups. First group was composed of 20 normal control group. Second group was composed of 10 patients (abnormal group) who had coronary artery disease. Subjects underwent myocardial perfusion SPECT ($^{201}Tl$ rest and $^{99m}Tc$-MIBI stress). Image acquisition and reconstruction were that rest stage was each step per 30, 15 seconds and stress stage was each step per 25, 13 seconds, OSEM and WBR methods were applied. Segmental perfusion and regional wall motion were applied 20-segment model of QPS, QGS algorithm in AutoQuant. Status of perfusion was composed of 5 point scoring system (0=normal, 1=mild, 2=moderate, 3=severe hypokinesia, 4=dyskinesia). Status of regional wall motion was also composed of 5 point scoring (0=normal, 1=mild, 2=moderate, 3=severe hypokinesia, 4=dyskinesia). We evaluated the agreement between conventional OSEM and WBR through automatic quantification value. Results: The agreement of rest segmental perfusion between conventional OSEM and WBR in normal patients was 99% (396/400, k=0.662, p<0.0001) and one of rest regional wall motion was 83.8% (335/400, k=0.283), the agreement of stress segmental perfusion was 95.8%(383/400, k=0.656), one of stress regional wall motion was 87.3% (349/400, k=0.390). The match rate of rest segmental perfusion in abnormal patients was 83% (166/200, k=0.605, p<0.0001) and one of rest regional wall motion was 55.5% (111/200, k=0.385), the agreement of stress segmental perfusion was 79.5% (159/200, k=0.682), one of stress regional wall motion was 63.5% (127/200, k=0.486). Conclusion: Compared to conventional OSEM, WBR method had a good agreement of segmental perfusion in myocardium in normal and abnormal groups. However regional wall motion showed meaningful low agreement. Although WBR offers high resolution and contrast ratio, it is not useful method for gated myocardial perfusion SPECT.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.28-32
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• 2014

Purpose Patient motion during myocardial perfusion SPECT can produce images that show visual artifacts and perfusion defects. This artifacts and defects remain a significant source of unsatisfactory myocardial perfusion SPECT. Motion correction has been developed as a way to correct and detect the patient motion for reducing artifacts and defects, and each motion correction uses different algorithm. We corrected simulated motion patterns with several motion correction methods and compared those images. Materials and Methods Phantom study was performed. The anthropomorphic torso phantom was made with equal counts from patient's body and simulated defect was added in myocardium phantom for to observe the change in defect. Vertical motion was intentionally generated by moving phantom downward in a returning pattern and in a non-returning pattern throughout the acquisition. In addition, Lateral motion was generated by moving phantom upward in a returning pattern and in a non-returning pattern. The simulated motion patterns were detected and corrected similarly to no-motion pattern image and QPS score, after Motion Detection and Correction Method (MDC), stasis, Hopkins method were applied. Results In phantom study, Changes of perfusion defect were shown in the anterior wall by the simulated phantom motions, and inferior wall's defect was found in some situations. The changes derived from motion were corrected by motion correction methods, but Hopkins and Stasis method showed visual artifact, and this visual artifact did not affect to perfusion score. Conclusion It was confirmed that motion correction method is possible to reduce the motion artifact and artifactual perfusion defect, through the apply on the phantom tests. Motion Detection and Correction Method (MDC) performed better than other method with polar map image and perfusion score result.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.9
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• pp.546-550
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• 2017

Ferroelectric properties are governed by domain structures and domain wall motions, so it is of significance to understand domain evolution processes under mechanical stress. In the present study, in situ piezoresponse force microscopy (PFM) observation under compressive stress was carried out for a near-morphotropic PZT. Both $180^{\circ}$ and $non-180^{\circ}$ domain structures were observed from PFM images, and their habit planes were identified using electron backscatter diffraction in conjunction with PFM data. By externally applied mechanical stress, needle-like $non-180^{\circ}$ domain patterns were broadened via domain wall motions. This was interpreted via phenomenological approach such that the total energy minimization can be achieved by domain wall motion rather than domain nucleation mainly due to the local gradient energy. Meanwhile, no motion was observed from curvy $180^{\circ}$ domain walls under the mechanical stress, validating that $180^{\circ}$ domain walls are not directly influenced by mechanical stress.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1903-1908
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• 2003

The motion of a small, heavy rigid particle in the shear flow on a stationary wall is investigated in the context of Stokes flow. The lift force proposed by Saffman(1965) and later modified by Mclaughlin(1991) and Mei(1992) is considered in the prediction of the particle motion far away from the wall. Later, the expression of the lift force is modified to take into account the effect of wall(Cherukat and Mclaughlin, 1994). In the analysis the gravity and buoyancy effect are also taken into account. An analytical and numerical results for the terminal velocities and trajectories of the particle after the enough lapse of time are presented.

• Journal of Magnetics
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• v.18 no.4
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• pp.417-421
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• 2013

The dominant magnetization reversal behavior of electrodeposited CoPt samples with various thicknesses deposited at different current densities was the domain wall motion by means of wall pinning. The magnetic interaction mechanism was dipolar interaction for all samples. The dipolar interaction strength was significantly affected by the sample thickness rather than by the current density, while the magnetic properties were closely related to the current density.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.171-176
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• 2003

Peristaltic mass transfer of fluid in a channel with standing wall oscillations is analyzed. Averaged nonlinear Navier-Stokes equations of motion are examined for a wide range of Reynolds numbers and external pressure drops. Nonpropogating wall oscillations with relatively big amplitudes essentially increase the liquid flow. Most effective intensifying of mass transfer occurred for low Reynolds numbers.

• Archives of Plastic Surgery
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• v.50 no.1
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• pp.10-16
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• 2023

Background The chest wall defects can be caused by various reasons. In the case of malignant tumor resection of the chest wall, it is essential to reconstruct the chest wall to cover the vital tissue and restore the pulmonary function with prevention of paradoxical motion. With our experience, we analyzed and evaluated the results and complications of the chest wall reconstructions followed by malignant tumor resection. Methods From 2013 to 2022, we reviewed a medical record of patients who received chest reconstruction due to chest wall malignant tumor resection. The following data were retrieved: patients' demographic data, tumor type, type of operation, method of chest wall reconstruction of the soft and skeletal tissue and complications. Results There were seven males and six female patients. The causes of reconstruction were 12 primary tumors and one metastatic carcinoma. The pathological types were seven sarcomas, three invasive breast carcinoma, and three squamous cell carcinomas. The skeletal reconstruction was performed in six patients. The series of the flap were eight pedicled latissimus dorsi (LD) myocutaneous flaps, two pectoralis major myocutaneous flap, two vertical rectus abdominis myocutaneous free flap, and one LD free flap. Among all the cases, only one staged reconstruction and successful reconstruction without flail chest. Most of the complications were atelectasis. Conclusion In the case of accompanying multiple ribs and sternal defect, skeletal reconstruction would need skeletal reconstruction to prevent paradoxical chest wall motion. The flap for soft tissue defect be selected according to defect size and location of chest wall. With our experience, we recommend the reconstruction algorithm for chest wall defect due to malignant tumor resection.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.403-412
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• 2006

The effect of a wall temperature on the soot deposition process from a diffusion flame to a solid wall was investigated in a microgravity environment to attain in-situ observations of the process. The fuel for the flames was an ethylene ($C_2H_4$). The surrounding oxygen concentration was 35% with surrounding air temperatures of $T_a=600K$. In the study, three different wall temperatures. $T_w$=300, 600, 800K, were selected as major test conditions. Laser extinction was adopted to determine the soot volume fraction distribution between the flame and burner wall. The experimental results showed that the maximum soot volume fractions at $T_w$=300, 800 K were $8.8{\times}10^{-6},\;9.2{\times}10^{-6}$, respectively. However, amount of soot deposition on wall surface was decreased because of lower temperature gradient near the wall with increasing wall temperature. A numerical simulation was also performed to understand the motion of soot particles in the flame and the characteristics of the soot deposition to the wall. The results from the numerical simulation successfully predicted the differences in the motion of soot particles by different wall temperature near the burner surface and are in good agreement with observed soot behavior that is, the 'soot line', in microgravity.

• The Korean Journal of Nuclear Medicine
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• v.29 no.4
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• pp.473-477
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• 1995

Information about regional wall motion obtained with gated $^{99m}Tc-MIBI$ SPECT was compared in 23 subjects(4 normals) to echocardiography or contrast left ventriculography. Gated SPECT study using 20-30 mCi $^{99m}Tc-MIBI$ were aquired lot 8 frames/RR interval (aqusition time=40min.) and processed with Cine Mode computer protocol. Regional wall motion was assessed by visual analysis. The concordance with echocardiography was 88% and with contrast ventriculography was 78%. We conclude that gated $^{99m}Tc-MIBI$ SPECT was effective in assessing the regional wall motion with the information of regional perfusion in one study.

• Journal of Chest Surgery
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• v.49 no.5
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• pp.366-373
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• 2016

Background: The aim of the study was to test the hypothesis that in patients with chronic complex sternum dehiscence, the use of muscle flap repair minimizes the occurrence of paradoxical motion of the chest wall (CWPM) when compared to sternal rewiring, eventually leading to better respiratory function and clinical outcomes during follow-up. Methods: In a propensity score matching analysis, out of 94 patients who underwent sternal reconstruction, 20 patients were selected: 10 patients underwent sternal reconstruction with bilateral pectoralis muscle flaps (group 1) and 10 underwent sternal rewiring (group 2). Eligibility criteria included the presence of hemisternum diastases associated with multiple (${\geq}$3) bone fractures and radiologic evidence of synchronous chest wall motion (CWSM). We compared radiologically assessed (volumetric computed tomography) ventilatory mechanic indices such as single lung and global vital capacity (VC), diaphragm excursion, synchronous and paradoxical chest wall motion. Results: Follow-up was 100% complete (mean $85{\pm}24months$). CWPM was inversely correlated with single lung VC (Spearman R=-0.72, p=0.0003), global VC (R=-0.51, p=0.02) and diaphragm excursion (R=-0.80, p=0.0003), whereas it proved directly correlated with dyspnea grade (Spearman R=0.51, p=0.02) and pain (R=0.59, p=0.005). Mean CWPM and single lung VC were both better in group 1, whereas there was no difference in CWSM, diaphragm excursion and global VC. Conclusion: Our study suggests that in patients with complex chronic sternal dehiscence, pectoralis muscle flap reconstruction guarantees lower CWPM and greater single-lung VC when compared with sternal rewiring and it is associated with better clinical outcomes with less pain and dyspnea.