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원관 내부의 Vane Swirlers에 의해 발생되는 압력 강하와 난류 소산에 관한 수치해석
신태석(Shin Taeseok),김현구(Kim Hyungoo),김상우(Kim Sangwoo),이도형(Lee Dohyung) 한국유체기계학회 2008 유체기계 연구개발 발표회 논문집 Vol.2008 No.-
The computational study of turbulent dissipation and total pressure drop behavior in vane swirlers was investigated. Simulation of steady flow through vane swirlers for various vane angles ranging from 15° to 60° in an increasing step of 15° Flow has been simulated by solving the appropriate governing equations of conservation of mass and momentum using the SIMPLE algorithm. Turbulence has been modeled using Reynolds Stress Model (RSM). First of all, this model includes the effect of the flow parameters, and assumes that the total pressure drop consists of two main partial pressure drops due to wall friction within the vane swirler and swirling motion of the air. Futhermore, assumes that the effect of the turbulent dissipation consists of Reynolds number and Swirl flow. The pattern of vortex dissipation is quite different from that variable vane angle.
Jinsung Kim,Hyungoo Shin,Heekyung Lee 대한신경외과학회 2023 Journal of Korean neurosurgical society Vol.66 No.6
Objective : The optic nerve sheath diameter (ONSD)/eyeball transverse diameter (ETD) ratio is a more reliable marker of intracranial pressure than the ONSD alone. We aimed to investigate the predictive value of the ONSD/ETD ratio (OER) for neurological outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). Methods : Adult patients with aSAH who visited the emergency department of a tertiary hospital connected to a South Korean university between January 2015 and December 2021 were included. Data on patient characteristics and brain computed tomography scan findings, including the ONSD and ETD, were collected using a predefined protocol. According to the neurological outcome at hospital discharge, the patients were divided into the unfavorable neurological outcome (UNO; cerebral performance category [CPC] score 3–5) and the favorable neurological outcome (FNO; CPC score 1–2) groups. The primary outcome was the association between the OER and neurological outcomes in patients with aSAH. Results : A total of 171 patients were included in the study, of whom 118 patients (69%) had UNO. Neither the ONSD (p=0.075) nor ETD (p=0.403) showed significant differences between the two groups. However, the OER was significantly higher in the UNO group in the univariate analysis (p=0.045). The area under the receiver operating characteristic curve of the OER for predicting UNO was 0.603 (p=0.031). There was no independent relationship between the OER and UNO in the multivariate logistic regression analysis (adjusted odds ratio, 0.010; p=0.576). Conclusion : The OER was significantly higher in patients with UNO than in those with FNO, and the OER was more reliable than the ONSD alone. However, the OER had limited utility in predicting UNO in patients with aSAH.
신재혁 ( Jaehyuk Shin ),한현구 ( Hyungoo Han ) 한국정보처리학회 2006 한국정보처리학회 학술대회논문집 Vol.13 No.1
계획기법 이란 목적을 달성하기 위해 일련의 행동 순서를 찾는 것이다. 계획 기법을 통해 수립된 많은 행동들을 로봇 등 에이전트가 실행할 때 예기치 않은 문제들이 발생하게 된다. 이러한 문제들을 실시간으로 해결하여 에이전트가 주어진 목적을 달성할 수 있도록 하여야 한다. 그러한 문제점을 해결하는 방법에는 반응 계획기법, 재 계획기법, 그리고 지역 복구기법 등이 있다. 본 논문에서는 재 계획기법과 지역 복구기법의 장점을 가지는 이정표상태 계획기법을 간단히 제안하고 이정표 상태의 생성 방법을 연구하였다. 이정표 상태들은 수립된 계획의 모의 실행을 통하여 생성하였으며 행동 실행에 관련된 조건들의 criticality value를 이용하는 방법과 계획에 나타나는 행동들의 빈도수를 이용하는 방법을 제안 하였다.
Do-Yun Kim,Han-Shin Jo,Hyungoo Yoon,Cheol Mun,Byung-Jun Jang,Jong-Gwan Yook IEEE 2010 IEEE transactions on industrial electronics Vol.57 No.4
<P>In this paper, the reverse-link interrogation range (RIR) of ultrahigh-frequency-band passive radio-frequency identification (RFID) is analyzed for single-input and single-output (SISO) and multiple-input and multiple-output (MIMO) systems with maximal-ratio combining in the pinhole channel, where each channel is modeled as an arbitrarily correlated Nakagami-m distribution. Under the assumptions of perfect channel estimation and no interference, the closed-form expression of average RIR is derived, involving various parameters, such as the number of antennas, correlation, reader structure, and Nakagami- m shaping factor. The results show that the employment of multiple antennas at a reader causes the received SNR to change favorably and contributes to the improvement of the average RIR. Particularly, for the bistatic structure and Rayleigh fading (m = 0 dB), a 3 × 3 MIMO-RFID system can achieve 60% gain in the average RIR compared to the SISO-RFID system. In order to consider more realistic environments, finally, we investigated the influence of interference and imperfect channel estimation on the average RIR of the MIMO-RFID system in the uncorrelated Rayleigh fading channel.</P>