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Yong‑Ho Kim,Hyo‑Sang Yoo,Jeong‑Han Lee,Ik‑Hyun Oh,Hyun‑Kuk Park,Hyeon‑Taek Son 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pureelements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloypowder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overallpowder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Sialloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification wasclearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformationof particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis ofthe sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remainedthe alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strengthof the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi,Al13Cr4Si4and Al8Cr5phases sintering process, resulting from the improvement of mechanical properties.
Clinical Significance of Preoperative Embolization for Non-Hypervascular Metastatic Spine Tumors
Yoo, Sung-Lim,Kim, Young-Hoon,Park, Hyung-Youl,Kim, Sang-Il,Ha, Kee-Yong,Min, Hyung-Ki,Seo, Jun-Yeong,Oh, In-Soo,Chang, Dong-Gune,Ahn, Joo-Hyun,Kim, Yong-Woo The Korean Neurosurgical Society 2019 Journal of Korean neurosurgical society Vol.62 No.1
Objective : The efficacy of preoperative embolization for hypervascular metastatic spine disease (MSD) such as renal cell and thyroid cancers has been reported. However, the debate on the efficacy of preoperative embolization for non-hypervascular MSD still remains unsettled. The purpose of this study is to determine whether preoperative embolization for non-hypervascular MSD decreases perioperative blood loss. Methods : A total of 79 patients (36 cases of preoperative embolization and 43 cases of non-embolization) who underwent surgery for metastatic spine lesions were included. Representative hypervascular tumors such as renal cell and thyroid cancers were excluded. Intraoperative and perioperative estimated blood losses (EBL), total number of transfusion and calibrated EBL were recorded in the embolization and non-embolization groups. The differences in EBL were also compared along with the type of surgery. In addition, the incidence of Adamkiewicz artery and complications of embolization were assessed. Results : The average age of 50 males and 29 females was $57.6{\pm}13.5$ years. Lung (30), hepatocellular (14), gastrointestinal (nine) and others (26) were the primary cancers. The demographic data was not significantly different between the embolization and the non-embolization groups. There were no significant differences in intraoperative EBL, perioperative EBL, total transfusion and calibrated EBL between two groups. However, intraoperative EBL and total transfusion in patients with preoperative embolization were significantly lower than in non-embolization in the corpectomy group (1645.5 vs. 892.6 mL, p=0.017 for intraoperative EBL and 6.1 vs. 3.9, p=0.018 for number of transfusion). In addition, the presence of Adamkiewicz artery at the index level was noted in two patients. Disruption of this major feeder artery resulted in significant changes in intraoperative neuromonitoring. Conclusion : Preoperative embolization for non-hypervascular MSD did not reduce perioperative blood loss. However, the embolization significantly reduced intraoperative bleeding and total transfusion in corpectomy group. Moreover, the procedure provided insights into the anatomy of tumor and spinal cord vasculature.
Yoo, Dong-Hwi,Park, Han-Bin,Jang, Won-Suk,Kwon, Oh-Bin,Choi, Ki-Won,Lee, Yu-Jin,Lee, Sang-Gun,Choi, Jae-Yong,Kim, Ho,Jang, Seon-Woo Korean AcupunctureMoxibustion Medicine Society 2021 대한침구의학회지 Vol.38 No.3
Background: Korean medicine treatment was assessed in patients with knee osteoarthritis (OA) according to subgroups of: sex, age, cause of knee OA, body mass index, hospitalization period, history, OA compartment, phenotype, and comorbidity. Methods: A retrospective review was performed of 122 inpatients who were admitted to the Hospital of Korean Medicine for Korean medicine treatment of knee pain, and were diagnosed with knee OA based on magnetic resonance imaging findings. Analysis of patient subgroups (sex, age, cause of knee OA, body mass index, hospitalization period, history, OA compartment, phenotype, and comorbidity) was carried out and treatments including acupuncture, cupping, pharmacopuncture, herbal medicine, chuna therapy, medicinal steaming therapy, manual therapy, and extracorporeal shock wave therapy were listed. The numeric rating scale (NRS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and 5-level EuroQol- 5 Dimension (EQ-5D-5L) scores were measured before and after treatment to assess the effects of treatment on pain and quality of life. Results: Seventeen males and 105 females were included in this study. Most patients were in their 60s. In the total study population, NRS, WOMAC, and EQ-5D-5L scores were improved statistically significant when comparing before and after treatment. The NRS and WOMAC scores improved statistically significant in the medial, patellofemoral, medial + patellofemoral, medial + lateral + patellofemoral compartment. Conclusion: Korean medicine treatment significantly reduced pain, stiffness, and physical dysfunction, and improved the quality of life of patients with knee OA, suggesting that it may be an effective alternative to the current conservative treatments.
Deriving a New Divergence Measure from Extended Cross-Entropy Error Function
Sang-Hoon Oh,Hiroshi Wakuya,Sun-Gyu Park,Hwang-Woo Noh,Jae-Soo Yoo,Byung-Won Min,Yong-Sun Oh 한국콘텐츠학회 2015 International Journal of Contents Vol.11 No.2
Relative entropy is a divergence measure between two probability density functions of a random variable. Assuming that the random variable has only two alphabets, the relative entropy becomes a cross-entropy error function that can accelerate training convergence of multi-layer perceptron neural networks. Also, the n-th order extension of cross-entropy (nCE) error function exhibits an improved performance in viewpoints of learning convergence and generalization capability. In this paper, we derive a new divergence measure between two probability density functions from the nCE error function. And the new divergence measure is compared with the relative entropy through the use of three-dimensional plots.