Structural organization of the quiescent core region in a turbulent channel flow

Yang, Jongmin,Hwang, Jinyul,Sung, Hyung Jin Elsevier 2016 The International journal of heat and fluid flow Vol.62 No.2

<P><B>Abstract</B></P> <P>The structural organization of the quiescent core region in a turbulent channel flow was explored using direct numerical simulation data at <I>Re<SUB>τ</SUB> </I> =930. The quiescent core region is the uniform momentum zone located at the center of the channel, and contains the highest momentum with a low level of turbulence. The boundary of the quiescent core region can be identified from the probability density function of the streamwise modal velocity. The streamwise velocity changes abruptly near the boundary of the core region. The abrupt jump leads the increase of the velocity gradient, which is similar to the vorticity thickness of the laminar superlayer at the turbulent/non-turbulent interface. The strong shear induced from the abrupt change is originated from the vortical structure lying on the boundary of the core region. The spanwise population densities of the prograde and retrograde vortices have a local maximum near the boundary of the core region. The prograde vortex dominantly contributes to the total mean shear near the core boundary and the contribution to the total mean shear rapidly decreases within the core region. The prograde and retrograde vortices form a counter-rotating vortex pair at the boundary of the core region associated with the nibbling mechanism. The boundary of the core region contains large-scale concave and convex features. The concave (convex) core interface is organized by the negative-<I>u</I> (positive-<I>u</I>) regions which induce the ejections (sweeps) around the core boundary.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The structural organization of the quiescent core region in a turbulent channel flow is explored. </LI> <LI> The quiescent core region is the uniform momentum zone located at the center of the channel. </LI> <LI> The boundary of the quiescent core region can be identified from the probability density function of the streamwise modal velocity. </LI> <LI> The prograde and retrograde vortices form a counter-rotating vortex pair at the boundary of the core region. </LI> </UL> </P>

Relationship between Investment Experience and Welfare Attitudes in Korean Society: Focusing on the Insufficiency of Labor Income and the Importance of Investment Income

Jongmin Yang 한국학술연구원 2023 Korea Observer Vol.54 No.4

Social Mobility in Comparative Perspective

Jongmin Yang 한국사회학회 2018 한국사회학회 심포지움 논문집 Vol.2018 No.5

Sun-induced chlorophyll fluorescence is more strongly related to absorbed light than to photosynthesis at half-hourly resolution in a rice paddy

Yang, Kaige,Ryu, Youngryel,Dechant, Benjamin,Berry, Joseph A.,Hwang, Yorum,Jiang, Chongya,Kang, Minseok,Kim, Jongmin,Kimm, Hyungsuk,Kornfeld, Ari,Yang, Xi Elsevier 2018 Remote sensing of environment Vol.216 No.-

<P><B>Abstract</B></P> <P>Sun-induced chlorophyll fluorescence (SiF) is increasingly used as a proxy for vegetation canopy photosynthesis. While ground-based, airborne, and satellite observations have demonstrated a strong linear relationship between SiF and gross primary production (GPP) at seasonal scales, their relationships at high temporal resolution across diurnal to seasonal scales remain unclear. In this study, far-red canopy SiF, GPP, and absorbed photosynthetically active radiation (APAR) were continuously monitored using automated spectral systems and an eddy flux tower over an entire growing season in a rice paddy. At half-hourly resolution, strong linear relationships between SiF and GPP (R<SUP>2</SUP> = 0.76) and APAR and GPP (R<SUP>2</SUP> = 0.76) for the whole growing season were observed. We found that relative humidity, diffuse PAR fraction, and growth stage influenced the relationships between SiF and GPP, and APAR and GPP, and incorporating those factors into multiple regression analysis led to improvements up to R<SUP>2</SUP> = 0.83 and R<SUP>2</SUP> = 0.88, respectively. Relationships between LUE<SUB>p</SUB> (=GPP/APAR) and LUE<SUB>f</SUB> (=SiF/APAR) were inconsistent at half-hourly and weak at daily resolutions (R<SUP>2</SUP> = 0.24). Both at diurnal and seasonal time scales with half-hourly resolution, we found considerably stronger linear relationships between SiF and APAR than between either SiF and GPP or APAR and GPP. Overall, our results indicate that for subdiurnal temporal resolution, canopy SiF in the rice paddy is above all a very good proxy for APAR at diurnal and seasonal time scales and that therefore SiF-based GPP estimation needs to take into account relevant environmental information to model LUE<SUB>p</SUB>. These findings can help develop mechanistic links between canopy SiF and GPP across multiple temporal scales.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Observed SiF is a better proxy of APAR than GPP. </LI> <LI> Found considerable environmental effects on the SiF-GPP relationships </LI> <LI> Improved GPP estimation by combining SiF or APAR with environmental variables </LI> <LI> Contribute to canopy SiF-GPP mechanistic links across multiple temporal scales </LI> </UL> </P>

Welfare States’ Policy Response to New Social Risk

Jongmin Yang(양종민) 서울대학교 사회발전연구소 2014 Journal of Asian Sociology Vol.43 No.2

This paper focuses on the trajectories of welfare state change through policy response to new social risks and methodologically categorizes the pattern of trajectories with sequence analysis. New social risks are the risks that people face in their life course due to the economic and social changes related to post-industrialization. By comparing a typology of welfare states based on trajectories of policy change in last three decades with Esping-Andersen’s threefold typologies of welfare states, we can determine whether welfare states maintain their existing welfare systems or change them. The results of sequence analysis on social expenditures and total tax revenue show that welfare regimes undergo a substantial change. In particular, conservative welfare regime countries show various trajectories when reacting to new social risks. This finding empirically supports studies that assert the transformation of the welfare state.

Unusual M ₂ -mediated metal-insulator transition in epitaxial VO ₂ thin films on GaN substrates

Yang, Hyoung Woo,Sohn, Jung Inn,Yang, Jae Hoon,Jang, Jae Eun,Cha, Seung Nam,Kim, Jongmin,Kang, Dae Joon Editions de Physique 2015 Europhysics letters Vol.109 No.2

<P>We report on the epitaxial growth of vanadium dioxide (VO2) thin films on (0001) GaN substrates using a radio frequency magnetron sputtering method and discuss their unusual M-2-mediated metal-insulator transition (MIT) properties. We found that large lattice misfits between the VO2 film and the GaN substrate could favor the stabilization of the intermediate insulating M-2 phase, which is known to be observed only in either doped or uniaxially strained samples. We demonstrated that the MIT in VO2 films on GaN substrates could be mediated via a monoclinic M-2 phase during the transition from a monoclinic M-1 to a rutile R phase. This was confirmed by temperature-dependent Raman studies that exhibited both an evident upshift of a high-frequency phonon mode (omega(V-O)) from 618 cm(-1) (M-1) to 645 cm(-1) (M-2) and a distinct peak splitting of a low-frequency phonon mode (omega(V-V)) at 221cm(-1) (M-2) for increasing temperatures. Moreover, a resistance change of four orders of magnitude was observed for VO2 thin films on GaN substrates, being indicative of the high quality of VO2 thin films. This study may offer great opportunities not only to improve the understanding of M-2-mediated MIT behavior in VO2 thin films, but also to realize novel electronic and optoelectronic devices. Copyright (C) EPLA, 2015</P>

복지국가 재편 경로에 대한 유형화 연구

양종민(Jongmin Yang) 비판과 대안을 위한 사회복지학회 2019 비판사회정책 Vol.- No.63

이 연구는 1980년대 중반 이후 사회적 위험 양상의 변화에 따른 복지국가의 정책적 대응과정 자체를 유형화함으로써 복지황금기 시기의 복지국가 모델이 그대로 유지되고 있는지, 아니면 새로운 유형으로 재편되고 있는지를 분석하고 있다. 그동안 사회적위험 양상의 변화에 따른 복지국가레짐의 유지 혹은 변화에 대한 많은 연구가 진행되었으나 사회적위험 양상의 변화에 따른 정책적 대응 ‘과정’을 반영한 연구는 많지 않다. 이 연구에서는 사회적 위험 양상의 변화에 따른 복지국가의 정책적 대응과정 자체를 분석단위로 하여 복지국가 유형화를 시도함으로써 점진적인 정책적 재조정(recalibration) 과정을 반영했을 때 여전히 복지황금기의 복지레짐은 유지되고 있는지, 아니면 새로운 양상으로 재편되고 있는지를 경험적으로 분석하고 있다. 시퀀스분석 결과를 바탕으로 군집분석을 실시한 결과 자유주의 레짐과 보수주의 국가들 내부에서 분화가 일어나고 있다는 사실에 주목할 필요가 있다. 이러한 복지국가 레짐의 재편과정을 통해 얻을 수 있는 함의는 새로운 사회적 위험에 대응하여 적극적인 정책적 대응을 추진하고 있는 국가들의 경우 증세가 필연적이라는 사실과 점진적인 제도변화 과정에서 행위자들의 이해관계를 어떻게 재조정하느냐가 관건이라는 점이다. This study examines whether the welfare state model of the golden era is maintained or restructured into a new typology by modeling the trajectory of welfare states’ policy response against changing nature of social risk after the mid 1980s. Although there are many studies on the maintenance or change of welfare state regime due to the changing nature of social risks, there are few studies that examine the process of policy response itself. In this manner, this study analyzes whether the welfare state model of the golden era is maintained or restructured into a new typology by categorizing the policy response process due to changing nature of social risks after the mid 1980s which reflect incremental policy recalibration. The result cluster analysis based on the sequence analysis reveal that the differentiation process is undergoing in liberal regime and conservative regime. The implications of this study are as follows. First, the increase of tax rate is inevitable considering the countries that actively responding to new social risks. Second, it is important to recalibrate interests of social actors during incremental institutional change.

기본소득 도입, 기존 복지제도의 확대, 증세의향에 대한 인식 간의 관계성 연구

양종민(Jongmin Yang) 비판과 대안을 위한 사회복지학회 2021 비판사회정책 Vol.- No.73

본 연구는 최근 학문적 · 정치적 · 사회적으로 이슈가 되고 있는 기본소득 도입에 대한 시민들의 인식구조를 분석하고 있다. 단순히 기본소득 도입에 대한 선호도를 분석한 기존 연구와 달리 본 연구에서는 기존 복지제도의 확대, 복지지출 확대를 위한 증세의향과의 관계성에 주목하여 기본소득 도입에 대한 다차원적인 인식구조를 파악하고자 했다. 그리고 인식구조에 유의미한 영향을 미치는 개인의 이해관계와 이념적 요인과 관련된 변수는 무엇인지 분석했다. 본 연구의 주요 결과는 다음과 같다. 우선 잠재집단분석(LCA) 결과 전체 응답자의 약 50%는 기본소득의 도입과 기존 복지지출의 확대, 복지를 위한 증세에 찬성하고 있다. 반면, 전체 응답자의 17.8%는 기본소득의 도입과 기존 복지지출의 확대, 복지를 위한 증세에 반대 입장을 보이고 있다. 한편, 전체 응답자의 32.5%는 기본소득의 도입에 유보적인 입장을 보이며, 기존 복지지출의 유지를 선호하고, 복지를 위한 증세에 대해서는 엇갈린 입장을 보여주고 있다. 다음으로 LCA를 통해 도출된 세 잠재집단에 속할 확률에 통계적으로 유의미한 영향을 미치는 개인의 이해관계와 이념적 요인과 관련된 변수는 무엇인지 파악하기 위해 다항로지스틱 회귀분석을 실행한 결과 남성에 비해 여성이 기본소득-복지제도 확대-증세 유보형에 속할 확률이 높으며 교육수준이 높을수록 기본소득-복지제도 확대-증세 유보형에 속할 가능성이 높다. 자가소유여부와 관련해서는 자가를 소유한 집단이 그렇지 않은 집단에 비해 기본소득-복지제도 찬성형에 속할 가능성이 낮다. 정치성향과 관련해서는 진보적인 성향일수록 기본소득-복지제도 확대-증세 찬성형에 속할 가능성이 높으며, 현재 복지제도에 대한 만족도가 높을수록 기본소득-복지제도 확대-증세 유보형에 속할 가능성이 높다. This study analyzes the structure of citizens" perception of the introduction of basic income, which has recently become an academic, political, and social issue. Unlike previous studies that simply analyzed preferences for the introduction of basic income, this study tried to understand the multidimensional perception structure of the introduction of basic income by paying attention to the relationship between the support for the expansion of the existing welfare system and the intention to raise taxes for the expansion of welfare spending. And we analyzed the variables related to personal interests and ideological factors that have a significant effect on the cognitive structure. The main results of this study are as follows. First of all, as a result of the latent group analysis (LCA), about 50% of all respondents are in favor of the introduction of a basic income, expansion of existing welfare expenditures, and tax increases for welfare. On the other hand, 17.8% of all respondents are opposed to the introduction of a basic income, expansion of existing welfare expenditures, and tax increases for welfare. On the other hand, 32.5% of the total respondents showed reservations about the introduction of basic income, preferring to maintain existing welfare expenditures, and showing mixed views on tax increases for welfare. Next, multinomial logistic regression analysis was conducted to find out what variables related to respondents" interests and ideological factors that significantly affect the probability of belonging to the three potential groups derived through LCA. There is a high probability of belonging to the system expansion reservation type, and the higher the education level, the higher the probability of belonging to the basic income-welfare system expansion reservation type. Regarding self-ownership, the group that owns a home is less likely to be in the favor of the basic income-welfare system than the group that does not. Regarding political orientation, progressive tendencies are more likely to belong to the type in favor of the basic income-welfare system expansion, and the higher the satisfaction with the current welfare system, the more likely it is to belong to the basic income-welfare system expansion-reservation type.

시장개방에 따른 사회적 위험을 해결하기 위한 국가의 복지지출 구성과 경제적 성과

양종민(Jongmin Yang) 한국사회학회 2013 韓國社會學 Vol.47 No.1

2008년에 발생한 전 세계적인 금융위기 이후 소득 양극화, 고령화, 저출산과 같은 사회문제에 대응하는 정부의 역할에 대한 중요성이 커지고 있다. 신자유주의가 팽배했던 지난 30여년간 최소한의 역할만을 요구받았던 국가는 이제 시장의 불확실성과 새로운 사회적 위험에 대해 적극적인 정책적 대응을 실행할 것을 요청받고 있다. 최근 한국 사회에서 활발하게 진행되고 있는 FTA와 복지국가를 둘러싼 논쟁도 국가의 역할에 대한 재조명에서 비롯되었다. 따라서 이 연구는 시장개방에 따른 사회적 위험에 대응하여 복지국가들이 선택한 사회복지지출의 구성과 그 경제적 성과에 대해서 분석하고자 한다. 특히 사회투자형 복지지출이 경제성장과 소득불평등 완화에 어떤 영향을 미쳤는지 알아보려고 한다. 시장개방에 대응하여 복지국가가 선택한 복지지출의 구성이 1인당 GDP 성장률과 소득불평등에 미친 영향을 알아보기 위해 회귀분석을 실행한 결과 노령인구 현금지출과 보건서비스지출이 부정적인 영향을 미친 반면 사회서비스지출은 긍정적인 영향을 미쳤다. 한편 모든 변수들이 소득불평등도를 낮추는 것으로 나타났지만 사회투자형 복지지출인 노동인구에 대한 현금지출과 사회서비스지출의 효과가 상대적으로 컸다. 이러한 분석결과는 FTA 확대와 같은 시장개방이 필연적인 한국의 경우 경제활동인구를 대상으로 한 사회복지지출의 집중적인 투자가 효과적일 수 있다는 점을 시사하고 있다. This study examines welfare states’ selection of social welfare expenditures and their economic performance in response to the social risk caused by market openness. Free trade agreement(FTA), one of the most controversial issues in Korea these days, might create new job opportunities and boost economic growth by broadening new markets, but it could also increase unemployment rate in uncompetitive industries and worsen income inequality. Dealing with outside risks, welfare states should spend social welfare expenditures efficiently and effectively. This study examines the economic outcome of welfare expenditure based on social investment state theory by categorizing social welfare expenditure specifically: cash expenditure is divided into old age-related cash and working age-related cash and service expenditure is divided into health and social service. The outcome of regression analysis reveals that whereas old age-related cash expenditure and health service cause a negative effect on GDP per capita growth rate, social service expenditure causes a positive effect. Concerning income inequality, although all variables have a positive effect on alleviating income inequality, the effect of the social investment expenditures ―working age-related cash and social service―is higher than that of old age-related expenditures. Therefore, in response to increasing FTA, Korea should focus on working age-related welfare expenditures to solve the social problems caused by market openness effectively and then make a positive feedback between market openness and welfare policy.

난류 관내 유동 내 벽 부착된 구조가 정지된 코어 영역 계면에 미치는 영향

양종민(Jongmin Yang),황진율(Jinyul Hwang),성형진(Hyung Jin Sung) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.4