통계 기법을 이용한 곡면 복원

Yoon, Min-Cheol,Lee, Yun-Jin,Lee, Seung-Yong,Ivrissimtzis, Ioannis,Seide1, Hans-Peter 한국컴퓨터그래픽스학회 2005 컴퓨터그래픽스학회논문지 Vol.11 No.2

곡면 복원이나 곡면 복원과 질은 관련이 있는 노말 추정을 하는 대부분의 방법은 결정론적인 알고리즘을 사용한다. 결정론적 알고리즘은 속도가 빠르고, 오차가 크지 않은 입력에 대해서는 좋은 질의 곡면 복원을 할 수 있다. 그러나 결정론적 방법의 특성상 이상치나 노이즈를 가진 데이터에 대해서는 안정된 복원 결과를 얻을 수 없다. 본 논문에서는 앙상블이라고 불리는 통계적인 방법을 사용해서 곡면 복원과 노말 추정을 하는 기존의 알고리즘을 개선한다. 앙상블 기법은 먼저 입력 점 집합을 무작위로 샘플링해서 점 집합의 부분집합을 만든다. 그리고 나서 만들어진 부분 집합에 독립적으로 결정론적인 알고리즘을 적용하여 결과를 얻어낸다. 마지막으로, 각각의 서로 다른 결과를 결합하여 더 우수한 최종결과를 얻어낸다. 널리 쓰이는 노말 추정 기법[11]과 Multi-level Partitions of Unity implicit [18]를 사용해서 앙상블이 효과적으로 노이즈가 많은 데이터를 처리할 수 있는 것을 보여준다.

n-ary hypergroups associated with n-ary relations

Seid Mohammad Anvariyeh,Somayyeh Momeni 대한수학회 2013 대한수학회보 Vol.50 No.2

The notion of n-ary algebraic hyperstructures is a general- ization of ordinary algebraic hyperstructures. In this paper, we associate an n-ary hypergroupoid (H, f) with an (n+ 1)-ary relation ρn+1 defined on a non-empty set H. Then, we obtain some basic results in this re- spect. In particular, we investigate when it is an n-ary Hv-group, an n-ary hypergroup or a join n-ary space.

Excessive Daytime Sleepiness and Associated Factors Among Women in Perinatal Period

Seid Jemal,Mohammed Emam,Aman Bilal Mohammed,Hassen Hassen Yimer 대한수면학회 2023 sleep medicine research Vol.14 No.1

Background and Objective Excessive daytime sleepiness (EDS) is an important public health issue requiring adequate screening and management to avoid such harmful consequences. The study aimed to assess the prevalence and risk factors of EDS in the perinatal period.Methods Institution-based cross-sectional study was carried out in selected public health institutions of Ethiopia on systematic selected 362 women during perinatal period. We used a validated Epworth daytime sleepiness tool to collect data. Epi-Info^TM 7 and SPSS version 26 were used for data entry and analysis, respectively. Bivariable and multivariable binary logistic regression analyses were conducted to determine the associated factors.Results The prevalence of EDS was 16.6% (95% CI: 12.6–20.7). Excessive pregnancy-related concern (adjusted odds ratio [AOR] = 0.232, 95% CI: 0.087–0.621), having depression symptoms (AOR = 8.045, 95% CI: 3.375–19.174), anxiety symptoms (AOR = 4.905, 95% CI: 2.083– 11.550) and having a chronic medical illness (AOR = 5.441, 95% CI: 2.273–13.021) were the factors associated with EDS.Conclusions The results of the current study suggested that perinatal EDS among women in northern part of Ethiopia is a highly prevalent and associated with excessive pregnancy concern, depression, anxiety, and medical illness.

Nitrite ion mitigates the formation of <i>N</i>-nitrosodimethylamine (NDMA) during chloramination of ranitidine

Seid, Mingizem Gashaw,Cho, Kangwoo,Lee, Changha,Park, Hyun-Mee,Hong, Seok Won Elsevier 2018 Science of the Total Environment Vol.633 No.-

<P><B>Abstract</B></P> <P>Ranitidine (RNT) has been an important tertiary amine precursor of <I>N</I>-nitrosodimethylamine (NDMA) in chlorine-based water treatment, due to reaction with monochloramine (NH<SUB>2</SUB>Cl) with exceptionally high molar yields up to 90%. This study examined the effects of nitrite ions (NO<SUB>2</SUB> <SUP>−</SUP>) on the kinetics of NDMA formation during the chloramination of RNT under variable concentrations of dissolved oxygen (DO, 0.7–7.5mg/L), RNT (5–30μM), NH<SUB>2</SUB>Cl (5–20mM), NO<SUB>2</SUB> <SUP>−</SUP> or NO<SUB>3</SUB> <SUP>−</SUP> (0–2mM) and pH (5.6–8.6). In the absence of the NO<SUB>2</SUB> <SUP>−</SUP>, the ultimate molar yield of NDMA after 6h of reaction was primarily influenced by [DO] and pH, while marginally affected by initial [RNT] and [NH<SUB>2</SUB>Cl]. A kinetic model, prepared in accordance with the reaction sequence of NDMA formation, suggested that the rate determining step was accelerated with increasing [NH<SUB>2</SUB>Cl]<SUB>0</SUB>, [DO], and pH. A Kinetic study together with ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometer (UPLC-Q-TOF MS) and gas chromatography (GC)/TOF MS analyses in parallel demonstrated that the nitrite ion inhibited the nucleophilic substitution of the terminal amine on NH<SUB>2</SUB>Cl, and reduced the pseudo-steady state concentration of <I>N</I>-peroxyl radicals, significantly decreasing the ultimate yields of NDMA.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nitrite ion inhibited NDMA formation during chloramination of ranitidine. </LI> <LI> DO, pH, and initial substrate concentrations also affected the molar yield. </LI> <LI> A three-parameter kinetic model was proposed based on NDMA formation pathway. </LI> <LI> Nitrite ion changed the specification of nitrosating agents. </LI> <LI> Nitrite ion interacted with <I>N</I>-proxy radicals. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Dynamic modeling and structural reliability of an aeroelastic launch vehicle

Pourtakdoust, Seid H.,Khodabaksh, A.H. Techno-Press 2022 Advances in aircraft and spacecraft science Vol.9 No.3

The time-varying structural reliability of an aeroelastic launch vehicle subjected to stochastic parameters is investigated. The launch vehicle structure is under the combined action of several stochastic loads that include aerodynamics, thrust as well as internal combustion pressure. The launch vehicle's main body structural flexibility is modeled via the normal mode shapes of a free-free Euler beam, where the aerodynamic loadings on the vehicle are due to force on each incremental section of the vehicle. The rigid and elastic coupled nonlinear equations of motion are derived following the Lagrangian approach that results in a complete aeroelastic simulation for the prediction of the instantaneous launch vehicle rigid-body motion as well as the body elastic deformations. Reliability analysis has been performed based on two distinct limit state functions, defined as the maximum launch vehicle tip elastic deformation and also the maximum allowable stress occurring along the launch vehicle total length. In this fashion, the time-dependent reliability problem can be converted into an equivalent time-invariant reliability problem. Subsequently, the first-order reliability method, as well as the Monte Carlo simulation schemes, are employed to determine and verify the aeroelastic launch vehicle dynamic failure probability for a given flight time.

n-ARY HYPERGROUPS ASSOCIATED WITH n-ARY RELATIONS

Anvariyeh, Seid Mohammad,Momeni, Somayyeh Korean Mathematical Society 2013 대한수학회보 Vol.50 No.2

The notion of $n$-ary algebraic hyperstructures is a generalization of ordinary algebraic hyperstructures. In this paper, we associate an n-ary hypergroupoid (H, $f$) with an ($n+1$)-ary relation ${\rho}_{n+1}$ defined on a non-empty set H. Then, we obtain some basic results in this respect. In particular, we investigate when it is an $n$-ary $H_v$-group, an $n$-ary hypergroup or a join $n$-ary space.

Dynamic modeling and structural reliability of an aeroelastic launch vehicle

Pourtakdoust, Seid H.,Khodabaksh, A.H. Techno-Press 2022 Advances in aircraft and spacecraft science Vol.9 No.3

The time-varying structural reliability of an aeroelastic launch vehicle subjected to stochastic parameters is investigated. The launch vehicle structure is under the combined action of several stochastic loads that include aerodynamics, thrust as well as internal combustion pressure. The launch vehicle's main body structural flexibility is modeled via the normal mode shapes of a free-free Euler beam, where the aerodynamic loadings on the vehicle are due to force on each incremental section of the vehicle. The rigid and elastic coupled nonlinear equations of motion are derived following the Lagrangian approach that results in a complete aeroelastic simulation for the prediction of the instantaneous launch vehicle rigid-body motion as well as the body elastic deformations. Reliability analysis has been performed based on two distinct limit state functions, defined as the maximum launch vehicle tip elastic deformation and also the maximum allowable stress occurring along the launch vehicle total length. In this fashion, the time-dependent reliability problem can be converted into an equivalent time-invariant reliability problem. Subsequently, the first-order reliability method, as well as the Monte Carlo simulation schemes, are employed to determine and verify the aeroelastic launch vehicle dynamic failure probability for a given flight time.

Optimal design of an MR damper valve for prosthetic knee application

Solomon Seid,Sujatha Chandramohan,S. Sujatha 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6

In this work, a magnetorheological (MR) damper valve is designed with the primary objective of controlling swing-phase damping in an above-knee prosthesis. Initially, a swing phase model of the desired single axis knee incorporating MR damper was modelled. The control parameters that govern damping force and displacement of the damper were identified and optimized to enable the prosthetic knee to produce near normal swing phase trajectory for ground walking as obtained from experimental data. Then, the MR damper valve is optimally designed by selecting typical performance indices of the damper for the intended application. A multi-objective optimization problem is formulated where the MR damper valve is constrained in a desired cylindrical volume defined by its radius and height. Effects of the geometrical design variables of the valve are analytically investigated by mapping finite element analysis (FEA) numerical responses with response surface method (RSM). The results show that the MR damper with designed damper valve enables the prosthetic knee to achieve near to normal swing phase trajectory, and compare to the existed MR damper, up to 71 % reduction by weight has been achieved.

Deep Contextual Reinforcement Learning for Solving Unit Commitment Problems

Awol Seid Ebrie,Chunhyun Paik,Yongjoo Chung,Young Jin Kim 한국경영과학회 2023 한국경영과학회 학술대회논문집 Vol.2023 No.5

Deep Contextual Reinforcement Learning for Solving Unit Commitment Problems

Awol Seid Ebrie,Chunhyun Paik,Yongjoo Chung,Young Jin Kim 대한산업공학회 2023 대한산업공학회 춘계학술대회논문집 Vol.2023 No.5