The Income Inequality of Wage Earners during 1993-98 in Korea

이장영(Lee Jang-Young),Michael Toney 한국인구학회 2005 한국인구학 Vol.28 No.2

이 논문은 1993년에서 1998년까지 임금 노동자들의 소득을 분석하였다. 한국의 경제와 그에 따른 노동자들의 소득은 1997년 말에 시작된 경제위기와 IMF 경제하에서 급격한 변화를 겪었다. 소득이 어떻게 변화하였는지 교육, 성, 연령을 중요한 변수로 여기는 인적 자본론을 바탕으로 분석하였다. 1993년에서 1998년까지 소득변화에 미치는 성 효과는 어떤 유형을 찾기 어렵지만 교육 효과는 점차 감소하고 있으며 연령 효과는 급격히 감소하고 있다. 소득변화에 미치는 세변수의 누적 효과는 증가하다가 감소하고 다시 증가하다가 감소하는 파도와 같은 모양을 보이지만 전체적으로는 점차 감소하고 있다. 이 논문은 패널조사로 구성된 원자료를 사용하였기 때문에 조사가 어려운 저소득층이 점차 줄어드는 제한점이 있다. The income of wage earners and the transition of the inequality of their income from 1993 through 1998 have been analyzed. Korea's economy went through an epochal change since the beginning of the IMF economy and the inequality of income, which is part of the change incurred by this situation, has been studied in this thesis. The 'human capital theory' has been chosen as the basis of study. Also, gender, educational background and age, which are the key variables of the 'human capital theory', have been set as independent variables to compare each variable's influence in the distribution of income. From 1993 to 1998, the effect of gender has shown a fluctuating pattern whereas the effect of education declined slowly and the effect of age rapidly. The accumulative effect of the three variables show a fluctuating pattern, but at a declining mode. Though discrimination against gender, educational background and age, in terms of income, is at a declining mode, it is apparent that it still exists. Especially, discrimination against gender is continuing at a fluctuating pattern.

The Effects of Status Inconsistency between Spouses on Migration in the United States: Propensities and Rural-Urban Destination Selections

Ji-Youn Lee(이지연),Michael B. Toney(마이클 토니),Helen E. Berry(헬렌 베리) 한국인구학회 2003 한국인구학 Vol.26 No.2

이 논문은 젊은 맞벌이 부부들 상호간에 교육정도와 소득수준의 차이가 가족의 지리적 이동에 미치는 영향을 지위불일치(status inconsistency)라는 개념을 통해서 살펴보았다. 미국의 패널데이타인 National Longitudinal Survey of Youth 79를 이용하여 부부간의 지위불일치가 이동 성향과 이동 방향에 미치는 영향을 로지스틱 모형으로 분석한 결과는 다음과 같다. 우선, 아내의 교육정도가 남편의 교육정도보다 높은 부부일수록 아내의 교육정도가 낮은 부부에 비해 이동할 확률이 높은 것으로 나타났다. 한편, 남편과 아내의 지위불일치는 도시와 농촌간의 이동방향에는 영향을 미치지 않았다. 그러나, 지위불일치가 가족의 이동에 미치는 영향에 있어서는 성에 따른 차이가 나타났다. 여성의 경우, 배우자의 지위가 높을 경우 이것이 이동성향에 있어 유의미한 차이를 나타냈지만, 남성의 경우는 배우자의 지위가 상대적으로 높다할지라도 이동확률에 별다른 영향을 미치지 않는 것으로 나타났다. 이러한 결과들은, 자녀 유무와 연령이 통제될 때, 가족의 지리적 이동확률과 방향은 아내와 남편간의 인적자본정도와 시장에서의 수익능력 차에 의해서 결정된다는 인적자본론이나 가족자원론과는 달리 전통적인 성역할 차이로 설명했던 성역할이론과 더 일치한다고 볼 수 있다. Using the panel data from the National Longitudinal Survey of Youth 79, we test the effects of relative status inconsistency within American young couples on the direction of migration as well as on migration propensities. Key findings in this study indicate that only couples In which the wife's education is greater than the husband's education are less likely to migrate than couples for which the wife's status Is as lower than the husband's. There are no differences in the propensity for rural couples to migrate to urban counties or for urban couples to migrate to rural counties based on status Inconsistency between spouses. However, we find that there is the gendered difference in the effect of status inconsistency on the probability of family migration. A spouse's higher status has an impact on a wife's probability of migration but does not affect a husband's migration propensity in a comparable situation. These findings are most consistent with a gender role perspective on migration since increases in the wife's status have little effect on family migration, once the presence and age of children is controlled.

The use of poly-cation oxides to lower the temperature of two-step thermochemical water splitting

Zhai, Shang,Rojas, Jimmy,Ahlborg, Nadia,Lim, Kipil,Toney, Michael F.,Jin, Hyungyu,Chueh, William C.,Majumdar, Arun The Royal Society of Chemistry 2018 ENERGY AND ENVIRONMENTAL SCIENCE Vol.11 No.8

<P>We report the discovery of a new class of oxides - poly-cation oxides (PCOs) - that consist of multiple cations and can thermochemically split water in a two-step cycle to produce hydrogen (H2) and oxygen (O2). Specifically, we demonstrate H2 yields of 10.1 ± 0.5 mL-H2 per g and 1.4 ± 0.5 mL-H2 per g from (FeMgCoNi)Ox (<I>x</I> ≈ 1.2) with thermal reduction temperatures of 1300 °C and 1100 °C, respectively, and also with background H2 during the water splitting step. Remarkably, these capacities are mostly higher than those from measurements and thermodynamic analysis of state-of-the-art materials such as (substituted) ceria and spinel ferrites. Such high-performance two-step cycles ≤1100 °C are practically relevant for today's chemical infrastructure at large scale, which relies almost exclusively on thermochemical transformations in this temperature regime. It is likely that PCOs with complex cation compositions will offer new opportunities for both fundamental investigations of redox thermochemistry as well as scalable H2 production using infrastructure-compatible chemical systems.</P>

On twin density and resistivity of nanometric Cu thin films

Barmak, Katayun,Liu, Xuan,Darbal, Amith,Nuhfer, N. Thomas,Choi, Dooho,Sun, Tik,Warren, Andrew P.,Coffey, Kevin R.,Toney, Michael F. American Institute of Physics 2016 Journal of Applied Physics Vol.120 No.6

Thermotropic Phase Transition of Benzodithiophene Copolymer Thin Films and Its Impact on Electrical and Photovoltaic Characteristics

Ko, Sangwon,Kim, Do Hwan,Ayzner, Alexander L.,Mannsfeld, Stefan C. B.,Verploegen, Eric,Nardes, Alexander M.,Kopidakis, Nikos,Toney, Michael F.,Bao, Zhenan American Chemical Society 2015 Chemistry of materials Vol.27 No.4

<P>We observed a thermotropic phase transition in poly[3,4-dihexyl thiophene-2,2′:5,6′-benzo[1,2-b:4,5-b′]dithiophene] (<B>PDHBDT</B>) thin films accompanied by a transition from a random orientation to an ordered lamellar phase via a nearly hexagonal lattice upon annealing. We demonstrate the effect of temperature-dependent molecular packing on charge carrier mobility (μ) in organic field-effect transistors (OFETs) and photovoltaic characteristics, such as exciton diffusion length (<I>L</I><SUB>D</SUB>) and power conversion efficiency (PCE), in organic solar cells (OSCs) using <B>PDHBDT</B>. The μ was continuously improved with increasing annealing temperature and <B>PDHBDT</B> films annealed at 270 °C resulted in a maximum μ up to 0.46 cm<SUP>2</SUP>/(V s) (μ<SUB>avg</SUB> = 0.22 cm<SUP>2</SUP>/(V s)), which is attributed to the well-ordered lamellar structure with a closer π–π stacking distance of 3.5 Å as shown by grazing incidence-angle X-ray diffraction (GIXD). On the other hand, <B>PDHBDT</B> films with a random molecular orientation are more effective in photovoltaic devices than films with an ordered hexagonal or lamellar phase based on current–voltage characteristics of <B>PDHBDT</B>/C60 bilayer solar cells. This observation corresponds to an enhanced dark current density (<I>J</I><SUB>D</SUB>) and a decreased <I>L</I><SUB>D</SUB> upon annealing. This study provides insight into the dependence of charge transport and photovoltaic characteristics on molecular packing in polymer semiconductors, which is crucial for the management of charge and energy transport in a range of organic optoelectronic devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-4/cm503773j/production/images/medium/cm-2014-03773j_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm503773j'>ACS Electronic Supporting Info</A></P>

Impact of regioregularity on thin-film transistor and photovoltaic cell performances of pentacene-containing polymers

Jiang, Ying,Hong, Sanghyun,Oh, Joon Hak,Mondal, Rajib,Okamoto, Toshihiro,Verploegen, Eric,Toney, Michael F.,McGehee, Michael D.,Bao, Zhenan The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.10

<P>Regioregular pentacene-containing polymers were synthesized with alkylated bithiophene (<B>BT</B>) and cyclopentadithiophene (<B>CPDT</B>) as comonomers. Among them, 2,9-conjugated polymers <B>PnBT-2,9</B> and <B>PnCPDT-2,9</B> achieved the best performance in transistor and photovoltaic devices respectively. The former achieved the most highly ordered structures in thin films, yielding ambipolar transistor behavior with hole and electron mobilities up to 0.03 and 0.02 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> on octadecylsilane-treated substrates. The latter achieved photovoltaic power conversion efficiencies up to 0.33%. The impact of regioregularity and direction of conjugation-extension (2,9 <I>vs.</I> 2,10), on thin-film order and device performance has been demonstrated for the pentacene-containing polymers for the first time, providing insight towards future functional material design.</P> <P>Graphic Abstract</P><P>Regioregular pentacene-bithiophene-based polymers exhibit disparate solid-state packing and field-effect transistor performance, with the 2,9-conjugation-extended polymer showing the highest molecular order and hole mobility. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm15483h'> </P>

Acoustic phonon lifetimes limit thermal transport in methylammonium lead iodide

Gold-Parker, Aryeh,Gehring, Peter M.,Skelton, Jonathan M.,Smith, Ian C.,Parshall, Dan,Frost, Jarvist M.,Karunadasa, Hemamala I.,Walsh, Aron,Toney, Michael F. National Academy of Sciences 2018 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.115 No.47

<▼1><P><B>Significance</B></P><P>Hybrid organic–inorganic perovskites are a promising class of materials for efficient and low-cost solar cells. Unlike conventional inorganic semiconductors such as silicon and gallium arsenide, hybrid perovskites feature significant dynamic disorder in their crystal structure. This dynamic disorder can be broadly classified into lattice vibrations (phonons) and molecular rotations. Phonons interact with charge carriers through electron–phonon coupling, which has substantial impacts on the operation of solar cells. Our study shows that acoustic phonons, the type responsible for transmitting heat in conventional semiconductors, have extraordinarily short lifetimes in the archetypal hybrid perovskite methylammonium lead iodide. These short lifetimes have direct implications on the cooling and transport of electrons and reflect a key difference between hybrid perovskites and conventional photovoltaic semiconductors.</P></▼1><▼2><P>Hybrid organic–inorganic perovskites (HOIPs) have become an important class of semiconductors for solar cells and other optoelectronic applications. Electron–phonon coupling plays a critical role in all optoelectronic devices, and although the lattice dynamics and phonon frequencies of HOIPs have been well studied, little attention has been given to phonon lifetimes. We report high-precision momentum-resolved measurements of acoustic phonon lifetimes in the hybrid perovskite methylammonium lead iodide (MAPI), using inelastic neutron spectroscopy to provide high-energy resolution and fully deuterated single crystals to reduce incoherent scattering from hydrogen. Our measurements reveal extremely short lifetimes on the order of picoseconds, corresponding to nanometer mean free paths and demonstrating that acoustic phonons are unable to dissipate heat efficiently. Lattice-dynamics calculations using ab initio third-order perturbation theory indicate that the short lifetimes stem from strong three-phonon interactions and a high density of low-energy optical phonon modes related to the degrees of freedom of the organic cation. Such short lifetimes have significant implications for electron–phonon coupling in MAPI and other HOIPs, with direct impacts on optoelectronic devices both in the cooling of hot carriers and in the transport and recombination of band edge carriers. These findings illustrate a fundamental difference between HOIPs and conventional photovoltaic semiconductors and demonstrate the importance of understanding lattice dynamics in the effort to develop metal halide perovskite optoelectronic devices.</P></▼2>

Manganese-cobalt hexacyanoferrate cathodes for sodium-ion batteries

Pasta, Mauro,Wang, Richard Y.,Ruffo, Riccardo,Qiao, Ruimin,Lee, Hyun-Wook,Shyam, Badri,Guo, Minghua,Wang, Yayu,Wray, L. Andrew,Yang, Wanli,Toney, Michael F.,Cui, Yi The Royal Society of Chemistry 2016 Journal of materials chemistry. A, Materials for e Vol.4 No.11

<P>Prussian Blue analogues (PBAs) have shown promise as electrode materials for grid-scale batteries because of their high cycle life and rapid kinetics in aqueous-based electrolytes. However, these materials suffer from relatively low specific capacity, which may limit their practical applications. Here, we investigate strategies to improve the specific capacity of these materials while maintaining their cycling stability and elucidate mechanisms that enhance their electrochemical properties. In particular, we have studied the electrochemical and structural properties of manganese hexacyanoferrate (MnHCFe) and cobalt hexacyanoferrate (CoHCFe) in an aqueous, sodium-ion electrolyte. We also studied manganese-cobalt hexacyanoferrate (Mn-CoHCFe) solid solutions with different Mn/Co ratios that combine properties of both MnHCFe and CoHCFe. The materials have the characteristic open-framework crystal structure of PBAs, and their specific capacities can be significantly improved by electrochemically cycling (oxidizing and reducing) both the carbon-coordinated Fe and the nitrogen-coordinated Co or Mn ions.<I>In situ</I>synchrotron X-ray diffraction studies and<I>ex situ</I>soft X-ray absorption spectroscopy combined with an in-depth electrochemical characterization provide insight into the different electrochemical properties associated with the Fe, Co, and Mn redox couples. We show that cycling the C-coordinated Fe preserves the crystal structure and enables the outstanding kinetics and cycle life previously displayed by PBAs in aqueous electrolytes. On the other hand, the N-coordinated Co and Mn ions exhibit a slower kinetic regime due to structural distortions resulting from the weak N-coordinated crystal field, but they still contribute significantly towards increasing the specific capacity of the materials. These results provide the understanding needed to drive future development of PBAs for grid-scale applications that require extremely high cycle life and kinetics.</P>