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황종관,윤명균,강대민 釜慶大學校 2002 釜慶大學校 論文集 Vol.7 No.-
This paper describes the energy absorption of a square tube in the cases of two models under axial compression by using PAM-CRASHTM. The first model is the model with various thickness under contant length, and the second model is the model with various length under constant thickness. To verify the energy absorption and the effects of dimensions, the standards were used as related density and specific energy and mean crushing load. The results were discussed by the relationship between crush load vs. deformation, related density vs. specific energy, crush load vs. mean crush load, and the relationship between mean crush load vs. specific energy.
절삭가공오차보상을 위한 기상측정 데이터기반 신경회로망의 응용
서태일,박균명,조명우,윤길상 한국공작기계학회 2001 한국공작기계학회 춘계학술대회논문집 Vol.2001 No.-
This paper presents a methodology of machining error compensation by using Artificial Neural Network(ANN) model based on the inspection database of On-Machine -Measurement(OMM) system. First, the geometric errors of the machining center and the probing errors are significantly reduced through compensation processes. Then, we acquire machining error distributions from a specimen work piece. In order to efficiently analyze the machining errors, we define two characteristic machining error parameters. These can he modeled by using an ANN model, which allows us to determine the machining errors in the domain of considered cutting conditions. Based on this ANN model, we try to correct the tool path in order to effectively reduce the errors by using an iterative algorithm. The iterative algorithm allows us to integrate changes of the cutting conditions according to the corrected tool path. Experimentation is carried out in order to validate the approaches proposed in this paper.
Probability Model of Massive Hemorrhage in Patients with Placenta Previa
( Myeong Gyun Choi ),( Jong Woon Kim ),( Wan Hu Jin ),( Yoon Ha Kim ) 대한주산의학회 2021 Perinatology Vol.32 No.2
Objective: The aim of this study was to identify the factors affecting massive hemorrhages in patients with placenta previa. We also made probability models and equations for massive hemorrhage. Methods: Seven hundred and sixty-four patients with placenta previa who underwent cesarean section from January 2011 to September 2019 were retrospectively reviewed. Massive hemorrhage was defined as a blood loss exceeding 1,500 mL or receiving over four units of packed red blood cells during cesarean section. Logistic regression analysis was used to create a probability model and identify the predictive factors for massive hemorrhage. Results: Two hundred and seventy-three (35.7%) patients had massive hemorrhages. Preoperative hemoglobin levels, multifetal gestation, emergent surgery, history of a previous cesarean section, location of the placenta, the presence of lacuna, placental adhesion, the type of placenta previa, and multiparity were selected predictive factors for massive hemorrhage. One hundred seventy-eight (23.3%) patients had placenta previa and a history of previous cesarean section. Among them, massive hemorrhage occurred in 101 (56.7%). The selected predictive factors for massive hemorrhage in patients with placenta previa and a history of previous cesarean section were emergent surgery, location of the placenta, the presence of lacuna, placental adhesion, and preoperative hemoglobin levels. An equation for massive hemorrhage in patients with placenta previa was created by combining variables. Conclusion: An equation for massive hemorrhage in patients with placenta previa was created by combining variables. These equations may help in managing placenta previa patients with high risk.
강명균(Myeong-Gyun Kang),이정훈(Jung-Hoon Lee),이승훈(Seung-Hoon Lee),전준수(Jun-Soo Jeon),김인용(In-Yong Kim),신용덕(Yong-Deok Shin) 대한전기학회 2014 전기학회논문지 Vol.63 No.3
The accelerated thermal aging of a CSPE were carried out for 0, 80.82, 161.63 days at 100℃, which are equal to 0, 40 and 80 years, respectively. The volume electrical resistivities of the non-accelerated thermally aged CSPE and the accelerated thermally aged CSPE for 40y and 80y were 9.620×10<SUP>12</SUP>∼1.246×10<SUP>13</SUP>Ω?cm, 5.066×10<SUP>12</SUP>∼7.576×10<SUP>12</SUP>Ω?cm and 7.195×10<SUP>12</SUP>∼9.208×10<SUP>12</SUP>Ω?cm at room temperature, respectively. The dielectric constant of the non-accelerated thermally aged CSPE and the accelerated thermally aged CSPE for 40y and 80y were 3.355∼4.030, 2.996∼3.963 and 3.020 ∼4.776 at room temperature, respectively. After seawater and freshwater flooding, the volume electrical resistivity of the CSPE trend slightly upward according to drying day at room temperature. After seawater flooding, the dielectric constant of the accelerated thermally aged CSPE were not measured. After seawater flooding, bright open pores of the accelerated thermally aged CSPE were partly transferred to dark close pores due to salinity. After freshwater flooding, dark close pores of the accelerated thermally aged CSPE were partly transferred to bright open pores because salinity of them is decreased. An insulation property of a cable in NPPs was decreased because of the seawater flooding, and an insulation property of them was recovered through the freshwater flooding. As a result, it is considered that an insulation property of a contaminated cable through Tsunami can be recovered if it is cleaned quickly.
Fail Safe가 적용된 날개 메커니즘 구현을 위한 UAV 플랫폼 및 덕트 설계
안명균(Myeong-Gyun Ahn),김찬규(Chan-Gyu Kim),이준서(Joon-Seo Lee),최동일(Dong-Il Choi) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
Traditional aircraft face limitations in dynamically adjusting wing lengths in constrained settings to reap aerodynamic benefits and spatial efficiencies. Moreover, in-flight self-repairs for wing damages induced by external circumstances are unfeasible. Addressing these issues, this paper introduces two distinct mechanisms: a balloon-assisted inflatable wing at the end of the wings and another based on the multistable inflatable origami structures. The former offers dynamic wing length adjustments in space-restricted urban environments, while the latter, with its multistable inflatable origami design, allows the detachment of a damaged wing and its replacement with an inflated origami-style wing. To realize these two mechanisms, directing fluid through the main wing is imperative. The paper proposes the use of an S duct as a solution and presents the design of both the S duct and a UAV platform. The feasibility of these mechanisms has been substantiated through mathematical equations for aircraft design and Computational Fluid Dynamics (CFD) analysis using Ansys.