수직자장하에서 원관내 자성유체의 거동에 관한 연구

박정우,유신오,서이수,Park, Joung-Woo,Ryu, Shin-Oh,Seo, Lee-Soo 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.1

In the present paper, we theoretically analyze the flow of magnetic fluids in a circular pipe with a vertical magnetic field and investigate the magnetic response by the external magnetic field. Theoretical study through the governing equation derived by Siliomis is carried out with numerical analysis by the Gauss Elimination Method. Using polar and magnetic effect parameters, theoretical equations and distributions for the velocity, vorticity, internal angular momentum and induced magnetization as the magnetic response are shown. Especially, in the region of strong magnetic field the specific property is appeared by finding a critical magnetic effect parameter for a polar effect parameter.

자성유체의 밀폐공간내의 열전달 특성에 관한 실험적 연구

박정우(Joung-Woo Park),서이수(Lee-Soo Seo),전철호(Chel-Ho Chen),박길문(Gil-Moon Park) 한국자기학회 2003 韓國磁氣學會誌 Vol.13 No.3

Natural convection of a magnetic fluid is different from that of Newtonian fluids because magnetic-body force exists in addition to gravity and buoyancy. In this paper, natural convection of a magnetic fluids (W-40) in a cubic cavity was examined by experimental method. One side wall was kept at a constant temperature (25℃), and the opposite side wall was also held at a constant but lower temperature (20℃). The magnetic fields of various magnitude were applied up and down by permanent magnets. We measured temperatures at 5 points which are the most suitable places in cavity by the analysis record. The thermo-sensitive liquid crystal film (R20C5A) was utilized in order to visualize wall-temperature distributions. Several kinds of experiments were carried out in order to clarify the influence of direction and intensity of magnetic fields on the natural convection. It was found that the natural convection of a magnetic fluids could be controlled by the direction and intensity of the magnetic fields.

반원관내 자성유체의 유동에 관한 연구

황성욱(Sung-Wok Hang),박정우(Joung-Woo Park),서이수(Lee-Soo Seo) 한국자기학회 2007 韓國磁氣學會誌 Vol.17 No.6

In this study, an analysis of natural convection of magnetic fluids in a closed-semicircular pipe was performed by the numerical methods. For the numerical method GSMAC method of Siliomis is used. From the results of numerical methods it is verified that the natural convection of the magnetic fluid, I investigated the nature convection phenomenon of the magnetic fluid with numerical analysis and was going to study the thermodynamic characteristic of the magnetic fluid. Because the effect of magnetic field control natural convection, we needed to find effective method to eliminate heat in the cure of heat transfer.

수평진동이 있는 용기내 자성유체 액면 동요 현상에 관한 연구

김대완(Dae-Wan Kim),박정우(Joung-Woo Park),서이수(Lee-Soo Seo) 한국자기학회 2012 韓國磁氣學會誌 Vol.22 No.5

In this paper, fluid movement of magnetic fluid which has free surface is investigated in a container subjected to a horizontal oscillation. Here, the vertical magnetic field is applied from the bottom of this container. The experiment is performed on the magnetic fluid in a rectangular and a cylindrical container and the effects of magnetic force exerted on the magnetic fluid are investigated on the resonance frequency and liquid surface displacement. The increase of magnetic field affects on the maximum resonance point and the liquid surface displacement. In result, it changes the amplitude of the surface wave and the period of sloshing fluid movement.

스마트도시사업 단계별 시민참여 수준 진단에 관한 연구

박지호 ( Ji-ho Park ),박정우 ( Joung-woo Park ),남광우 ( Kwang-woo Nam ) 한국지리정보학회 2021 한국지리정보학회지 Vol.24 No.2

글로벌 스마트도시 추진 동향을 기반으로 2018년‘4차산업혁명위원회’는 국내 스마트도시 정책의 방향과 관련하여‘지속가능성’과‘사람중심’을 핵심 키워드로 선정하였다. 이에 따라 국내 스마트도시사업 추진단계별로 적극적인 시민중심의 혁신 방법론인 리빙랩 프로그램을 적용하고 있다. 스마트도시는 리빙랩을 통해 시민이 중심이 되어 지역문제를 발굴하고, 공공·전문가와 함께 시민의 니즈(Needs)를 반영한 해결방안 도출을 통해 지속가능한 도시문제 해결방안 및 지역발전방안을 마련하고 있다. 그러나 상대적으로 오랜 시간 운영된 도시재생사업과 비교할 때 스마트도시사업의 시민참여는 그 수준이나 지속가능성에서 상당한 차이가 있는 것으로 나타났다. 이에 본 연구는 2018년부터 2019년까지 추진된 스마트도시사업에서 수행한 리빙랩 프로그램 사례를 대상으로 도시재생사업 단계별 시민참여 특성과의 비교 분석과 Arnstein의‘참여의 사다리’모형을 기준으로 한 시민참여 활동 수준진단을 수행하였다. 진단결과, 스마트도시사업에서 수행된 리빙랩에 나타난 시민참여 활동은 스마트도시서비스의 선정이나 해결책 구성 등에 상대적으로 높은 수준의 권한을 기반으로 지역주민의 수요에 맞는 스마트도시서비스를 선택하고 지역에 맞는 서비스의 기술수준이 결정되는 데 큰 영향을 보이고 있었다. 그러나 스마트도시 구축사업만을 위한 단발성 성격의 시민참여단 모집으로 사업 종료 후 에는 대부분의 시민참여활동이 중단되고 있었다. 이에 반해 도시재생사업의 시민참여 활동은 지역공동체 중심으로 사업 계획 단계부터 사업 종료 후 운영단계까지 지속적인 운영·관리 방안이 도출되고 있었다. 본 연구는 이와 같은 도시재생사업과 스마트도시사업간의 시민참여의 특성 비교와 수준진단을 통해 보다 지속가능한 스마트도시 구현을 위한 시민참여활성화 방안을 제시하였다. Based on the global smart city promotion trend, in 2018, the“Fourth Industrial Revolution Committee”selected“sustainability”and“people-centered”as keywords in relation to the direction of domestic smart city policy. Accordingly, the Living Lab program, which is an active citizen-centered innovation methodology, is applied to each stage of the domestic smart city construction project. Through the Living Lab program, and in collaboration with the public and experts, the smart city discovers local issues as it focuses on citizens, devises solutions to sustainable urban problems, and formulates a regional development plan that reflects the needs of citizens. However, compared to citizen participation in urban regeneration projects that have been operated for a relatively long time, participation in smart city projects was found to significantly differ in level and sustainability. Therefore, this study conducted a comparative analysis of the characteristics of citizen participation at each stage of an urban regeneration project and, based on Arnstein’s“Participation Ladder”model, examined the level of citizen participation activities in the Living Lab program carried out in a smart city commercial area from 2018 to 2019. The results indicated that citizen participation activities in the Living Lab conducted in the smart city project had a great influence on selecting smart city services, which fit the needs of local residents, and on determining the technological level of services appropriate to the region based on a relatively high level of authority, such as selection of smart city services or composition of solutions. However, most of the citizen participation activities were halted after the project’s completion due to the one-off recruitment of citizen participation groups for the smart city construction project only. On the other hand, citizens’ participation activities in the field of urban regeneration were focused on local communities, and continuous operation and management measures were being drawn from the project planning stage to the operation stage after the project was completed. This study presented a plan to revitalize citizen participation for the realization of a more sustainable smart city through a comparison of the characteristics and an examination of the level of citizen participation in such urban regeneration and smart city projects.

균제도 구현을 위한 비구면 조명렌즈 설계 연구

김세민(Se Min Kim),박정우(Joung Woo Park),전언찬(Eon Chan Jeon) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.2

원관내 자성유체의 Rheology 특성에 관한 연구

전언찬(Eon-Chan Jeon),박정우(Joung-Woo Park),김태호(Tae-Ho Kim),김수용(Soo-Yong Kim) 한국기계가공학회 2008 한국기계가공학회지 Vol.7 No.2

In the present paper, we theoretically analyze the flow of magnetic fluids in a circular pipe with a vertical magnetic field and investigate the magnetic response by the external magnetic field. Theoretical study through the governing equation derived by Siliomis is carried out with numerical analysis by the Gauss Elimination Method. Using polar and magnetic effect parameters, theoretical equations and distributions for the velocity, apparent viscosity as the magnetic response are shown. Especially, in the region of strong magnetic field the specific property is appeared by finding a critical magnetic effect parameter for a polar effect parameter.

이젝터의 노즐 형상이 흡입유량에 미치는 영향

김유준(Yoo-Jun Kim),박정우(Joung-Woo Park),서이수(Lee-Soo Seo) 한국유체기계학회 2009 한국유체기계학회 논문집 Vol.12 No.6

반원관내 자성유체의 자연대류에 관한 연구

황성욱(Sung-Wook Hwang),박정우(Joung-Woo Park),서이수(Lee-Soo Seo) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

In this paper, natural convection of a magnetic fluids(W-40) in a half circular pipe enclosure are investigated by numerical and experimental method. One side wall is kept at a constant temperature(25℃), and the opposite side wall is also kept at a constant temperature(20℃). Under above conditions, various magnitudes of the magnetic fields were applied up. Theoretical study through the governing equation derived by Siliomis is carried out with numerical analysis by the GSMAC Method. And the thermo-sensitive liquid crystal film(R20C5A) is utilized in order to visualize wall-temperature distributions as an experimental method. This study has resulted in the following fact that the natural convection of a magnetic fluids are controlled by the direction and intensity of the magnetic fields.

자성유체의 Benard 유동 및 제어 특성에 관한 수치해석

진성호(Sung-Ho Jin),박정우(Joung-Woo Park),서이수(Lee-Soo Seo) 대한설비공학회 2001 대한설비공학회 학술발표대회논문집 Vol.2001 No.-