대형 와 모사를 통한 레이놀즈 수 증가에 따른 혼합 탱크 내의 유동 구조의 연구

윤현식,전호환,하만영,Yoon, Hyun-Sik,Chun, Ho-Hwan,Ha, Man-Yeong 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.9

The stirred tank reactor is one of the most commonly used devices in industry for achieving mixing and reaction. Here we report on results obtained from the large eddy simulations of flow inside the tank performed using a spectral multi-domain technique. The computations were driven by specifying the impeller-induced flow at the blade tip radius. Stereoscopic PlY measurements (Hill et al. $^{(1)}$) along with the theoretical model of the impeller-induced flow (Yoon et al. $^{(2)}$) were used in defining the impeller-induced flow as superposition of circumferential, jet and tip vortex pair components. Large eddy simulation of flow in a stirred tank was carried out for the three different Reynolds numbers of 4000, 16000 and 64000. The effect of different Reynolds numbers is well observed in both instantaneous and time averaged flow fields. The instantaneous and mean vortex structures are identified by plotting an isosurfaces of swirling strength for all Reynolds numbers. The Reynolds number dependency of the non-dimensional eddy viscosity, resolved scale and subgrid scale dissipations is clearly shown in this study.

대형 와 모사를 사용한 혼합 탱크 내의 농도장과 유동장의 동시 해석

윤현식,전호환,하만영,Yoon, Hyun-Sik,Chun, Ho-Hwan,Ha, Man-Yeong 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.9

Transport of a scalar quantity, such as chemical concentration or temperature, is important in many engineering applications and environmental flows. Here we report on results obtained from the large eddy simulations of flow and concentration fields inside the tank performed using a spectral multi-domain technique. The computations were driven by specifying the impeller-induced flow at the blade tip radius (Yoon et al.). This study focused on the concentration development at different molecular diffusivities in a stirred tank operated under turbulent conditions. The main objective of the work presented here is to study the large-scale mixing structure at different molecular diffusivities in a stirred tank by using the large eddy simulation. The time sequence of concentration and flow fields shows the flow dependency of the concentration development. The presence of spatial inhomogenieties is detailed by observing the time variation oflocal concentration at different positions.

대형 와 모사법 (LES)을 이용한 사각 실린더 주위의 난류 유동장 해석

윤현식(Hyun Sik Yoon),전호환(Ho Hwan Chun),정광효(Kwang Hyo Jung) 대한조선학회 2006 大韓造船學會 論文集 Vol.43 No.6

NoC기반의 BP 디지털 신경망의 설계

윤현식(Hyun-Sik Yoon) 한국정보기술학회 2012 한국정보기술학회논문지 Vol.10 No.8

In this thesis, I propose the design method of digital neural networks based on Network-on-Chip(NoC). NoC technology provides on-chip network arranged in a row, by using packet protocol through a series of routers. On the other hand, research on digital neural networks was delayed because of complexity that it should be composed of matrix of numerous processing element (PE). Therefore if digital neural network(DNN) is designed on the basis of NoC, communication load between PEs, and execution time will be decreased, and design of low power will be possible. For consideration of communication between chips, characteristics of network like this may include receiving socket at the terminal of network to permit independence to cores, and expandability that network may be expanded or reduced at need, as well as standard interface protocol. And various architecture of digital neural network can be implemented because recomposition and modification of digital neural network is easy.

MESH형 무선이동망의 설계에 관한 연구

윤현식(Hyun-sik Yoon) 한국정보기술학회 2008 한국정보기술학회논문지 Vol.6 No.4

Amazing progress in research of wireless communication network technology has created variety type of advanced wireless systems. This paper accomplishes the design of wireless mesh networks appling non infrastructure wireless network services. Specially, introduce economical coverage expandable method on the limited public area. The result of study in this paper will provide the more efficient wireless mesh networks technology in the field of wireless ad hoc networks.

초고밀도 무선 네트워크 성능 평가를 위한 레이트레이싱 시뮬레이터

윤현식(Hyun Sik Yoon),이미현(Mi Hyun Lee),손하영(Ha Young Son),최계원(Kae Won Choi) 한국통신학회 2020 한국통신학회 학술대회논문집 Vol.2020 No.11

IIoT 기반 사출성형공정 품질 예지보전을 위한 센서 전처리 연구

윤현식(Hyun Sik Yoon),박건우(Kun Woo Park),김덕영(Duck Young Kim) 대한전기학회 2019 정보 및 제어 심포지엄 논문집 Vol.2019 No.10

AI에 대한 법인격 부여의 근거로서 탈인간중심적 법이론의 가능성

윤현식 ( Yoon Hyun Sik ) 민주주의법학연구회 2021 민주법학 Vol.- No.76

AI 분야의 포스트 담론, 특히 ‘탈인간중심주의’는 헌법학에서도 흥미로운 논의이다. 탈인간중심주의는 인간의 존엄성에 기반한 기본적 인권과 이를 보장하기 위한 체제를 규정하는 헌법의 기반을 흔들 수도 있어 주의 깊게 검토해야 한다. 가장 활발하게 논의되는 주제는 AI에게 법인격을 부여하는 문제이다. 탈인간중심주의는 인간의 지위를 다른 모든 존재와 동일하게 보도록 함으로써 AI에 대한 법인격 부여의 가능성을 높여준다. 탈인간중심주의적 관점에서, AI에게 법인격을 부여하는 것은 AI로 인해 발생하는 법률문제에 효과적으로 대응하는 방안이 될 수 있다. 그러나 강인공지능 또는 초인공지능을 전제로 하는 AI 법인격 부여 주장은 여러 문제점을 안고 있다. 첫째, 이 견해는 AI에 대한 오해에서 비롯되었다. 둘째, 이 견해는 추상적 관념의 결과물로서 법적 현실을 고려하지 못한다. 셋째, 이러한 견해는 자칫 인간이 져야 할 법적 책임을 회피하는 경로로 활용될 수 있다. 따라서 탈인간중심주의에 근거한 AI 법인격 부여는 법적 실익이 없다. AI와 인간 간에 형성되어야 할 새로운 기준(new normal)은 인간중심주의의 재구성이다. 헌법학은 탈인간중심주의라는 추상적 관념에 사로잡히기보다는, 인간중심주의를 더욱 근본적으로 탐구하여야 한다. The post-discourse in the field of AI, especially ‘post-anthropocentrism’, is an interesting discussion in Constitutional Law studies. The post-anthropocentrism should be carefully considered because it may shake the foundation of the Constitutional Law which stipulates fundamental human rights based on human dignity and a system to guarantee them. The most actively discussed topic is the issue of granting legal personality to AI. The post-anthropocentrism raises the possibility of granting legal personality to AI by making the human status equal to all other beings. From the post-anthropocentric perspective, granting a legal personality to AI can be an effective way to respond to legal problems caused by AI. However, the argument for granting legal personality to AI has several problems because its premise is AGI or ASI. First, this view stems from a misunderstanding of AI. Second, this view is the result of an abstract idea that does not take legal reality into account. Third, this view can be used as a route to evade legal responsibility that human beings should bear. Therefore, granting legal personality to AI based on the post-anthropocentrism has no legal benefit. A new normal to be formed between AI and the human is the reconstruction of the anthropocentrism. Constitutional Law studies should explore the anthropocentrism more radially rather than being caught up in the abstract notion of the post-anthropocentrism.

간헐포기 슬러지 소화시 상징수증의 영양염류 수질특성

윤현식(Hyun Sik Yoon),최용수(Yong Su Choi),이영대(Young Dae Lee),홍석원(Seok Won Hong),정익재(Ik Jae Chung) 한국물환경학회 2001 한국물환경학회지 Vol.17 No.2

In general a waste activated sludge is biologically stabilized by either aerobic or aerobic digestion. Typical problems associated with these two processes include high energy requirement, capital cost, and high load to the main wastewater treatment process due to returned digestion supernatant. To overcome these problems in conventional digestion processes, the intermittently aerated sludge digestion, which is operated under combined aerobic and anoxic condition, has been studied for another alternative. In order to understand the behaviors of nutrients in a supernatant of sludge digestion, intermittently aerated batch and continuous digestion experiments were investigated in this study. In a batch digestion, it is shown that nitrogen and phosphorus concentration in the intermittently aerated digestion are less than those in controlled batch digestions: anaerobic digestion without air supply and aerobic digestion with continuous air supply. The endogenous nitrate respiration following the nitrification and the P-uptake by the residual microbes are alternatively occurred in the intermittently aerated digestion. In the continuous digestion, nitrogen and phosphorus concentration in the effluent were examined under air on/off operating condition.

금융 산업에서 발생하는 랜섬웨어 공격에 대한 FAIR 기반의 손실 측정 모델 분석

윤현식(Hyun-sik Yoon),송경환(Kyung-hwan Song),이경호(Kyung-Ho Lee) 한국정보보호학회 2017 정보보호학회논문지 Vol.27 No.4

랜섬웨어가 확산됨에 따라 공격 대상이 개인에서 단체로 변하게 되었고 더 지능적이고 조직적으로 변하게 되었다. 이에 금융 산업을 포함한 국내의 기반시설들은 랜섬웨어의 위협에 대해 더 이상 무시 할 수 없는 단계로 접어들 고 있다. 이러한 보안이슈에 대응하기 위해 기관들은 정보보호 관리체계인 ISMS를 사용하고 있지만 피해가 발생 했을 시 발생하는 피해규모를 산정 할 수 없어 경영진이 피해 현황에 대한 의사결정을 하는 것에 어려움이 있다. 본 논문에서는 ISMS의 문제로 여기어 지는 리스크에 대한 피해규모의 파악 및 합리적인 피해규모 산정을 시나리오를 기반으로 진행되는 FAIR 기반의 손실 측정모델을 통해 금융 산업에 랜섬웨어 공격이 미칠 수 있는 손실 및 위험을 확인하며 ISMS를 수정하는 것이 아닌 현재 적용되어 있는 ISMS 및 ISO 27001의 통제항목을 적용하여 손해금액을 낮출 수 있는 방안을 제시한다. As Ransomware spreads, the target of the attack shifted from a single personal to organizations which lead attackers to be more intelligent and systematic. Thus, Ransomware"s threats to domestic infrastructure, including the financial industry, have grown to a level that cannot be ignored. As a measure against these security issues, organizations use ISMS, which is an information protection management system. However, it is difficult for management to make decisions on the loss done by the security issues since amount of the damage done can not be calculated with just ISMS. In this paper, through FAIR-based loss measurement model based on scenario"s to identify the extent of damage and calculate the reasonable damages which has been considered to be the problem of the ISMS, we identified losses and risks of Ransomeware on the financial industry and method to reduce the loss by applying the current ISMS and ISO 27001 control items rather than modifying the ISMS.