A fresh look at contemporary perspectives on urban housing affordability

Marietta E. A. Haffner,Kath Hulse 서울시립대학교 도시과학연구원 2021 도시과학국제저널 Vol.25 No.1

The literature on housing affordability has grown rapidly since Hulchanski [1995, p. 489. The concept of housing affordability: six contemporary uses of the housing expenditure-to-income ratio. Housing Studies, 10(4), 471–491] declared that housing researchers should avoid using the term since it is not a robust concept and measurement often lacks validity. In the ensuing 24 years, however, scholars have continued to debate the definition and measurement of housing affordability as well as the prevalence and type of ‘housing affordability problems’ in various countries. This paper is a think piece which takes a fresh look at housing affordability as a concept which has persisted despite considerable contestation and scepticism about its use. It provides a critical and multi-disciplinary assessment of housing affordability starting with early conceptualization of the nexus between economic principles and social norms about housing and living standards to a reworking of housing affordability in the twenty-first century as an urban issue affecting lower and middle-income households in cities, as a consequence of the financialization of housing and urban restructuring. It argues that the housing affordability concept has been repurposed such that the focus is less on understanding housing expenditures in contributing to poverty and disadvantage within the domain of social policy and more on the urban policy challenges of growing inequities in access to urban resources. The paper highlights the challenges for urban policy in adopting and adapting rather than rejecting a multi-dimensional concept of housing affordability and consequently the importance of new ways of measuring urban housing affordability.

A "GAP-Model" based Framework for Online VVoIP QoE Measurement

Calyam, Prasad,Ekici, Eylem,Lee, Chang-Gun,Haffner, Mark,Howes, Nathan The Korea Institute of Information and Commucation 2007 Journal of communications and networks Vol.9 No.4

Increased access to broadband networks has led to a fast-growing demand for voice and video over IP(VVoIP) applications such as Internet telephony(VoIP), videoconferencing, and IP television(IPTV). For pro-active troubleshooting of VVoIP performance bottlenecks that manifest to end-users as performance impairments such as video frame freezing and voice dropouts, network operators cannot rely on actual end-users to report their subjective quality of experience(QoE). Hence, automated and objective techniques that provide real-time or online VVoIP QoE estimates are vital. Objective techniques developed to-date estimate VVoIP QoE by performing frame-to-frame peak-signal-to-noise ratio(PSNR) comparisons of the original video sequence and the reconstructed video sequence obtained from the sender-side and receiver-side, respectively. Since processing such video sequences is time consuming and computationally intensive, existing objective techniques cannot provide online VVoIP QoE. In this paper, we present a novel framework that can provide online estimates of VVoIP QoE on network paths without end-user involvement and without requiring any video sequences. The framework features the "GAP-model", which is an offline model of QoE expressed as a function of measurable network factors such as bandwidth, delay, jitter, and loss. Using the GAP-model, our online framework can produce VVoIP QoE estimates in terms of "Good", "Acceptable", or "Poor"(GAP) grades of perceptual quality solely from the online measured network conditions.

Validation of Brewer and Pandora measurements using OMI total ozone

Baek, Kanghyun,Kim, Jae H.,Herman, Jay R.,Haffner, David P.,Kim, Jhoon Elsevier 2017 Atmospheric environment Vol.160 No.-

<P>Korea will launch the Geostationary Environment Monitoring Spectrometer (GEMS) instrument in 2018 onboard the Geostationary Korean Multi-Purpose Satellite to monitor tropospheric gas concentrations with high temporal and spatial resolutions. The purpose of this study is to examine the performance of total column ozone (TCO) measurements from ground-based Pandora and Brewer instruments that will be used for validation of the GEMS ozone product. Satellite measurements can be used to detect erroneous outliers at a particular ground station, which deviate significantly from co-located satellite measurements relative to other stations. This is possible because a single satellite retrieval algorithm is used to process the entire satellite dataset, and instrument characteristics typically change slowly over the life of the satellite. Thus, the short-term stability (months) of satellite measurements can be used to estimate the performance of the ground-based measurement network as well as to identify potential problems at individual stations. As a reference for satellite ozone measurements, we have selected TCO data derived from OMI-TOMS V8.5 algorithm, because it is a robust algorithm that has been well studied to identify its various error sources. We validated ground-based Brewer and Pandora TCO measurements using OMI-TOMS TCO data collected over South Korea from March 2012 to December 2014. The Brewer TCO measurements at Pohang showed significant deviation from overall seasonal variation during the study period. In addition, in the presence of clouds, Pandora TCO measurements are unusually 7% higher than OMI-TOMS TCO data. To filter out these cloud-contaminated data, we applied a Kalman filter to the Pandora measurements. The diurnal variation in the Kalman-filtered Pandora data agrees well with the Brewer data, and the correlation of Kalman-filtered Pandora data with OMI-TOMS TCO is significantly improved from 0.89 to 0.99 at Seoul and from 0.93 to 0.99 at Busan. (C) 2017 Published by Elsevier Ltd.</P>

Validation of the on-line aerosol retrieval and error characterization algorithm from the OMI Near-UV observations during the DRAGON-NE Asia 2012 campaign

정욱교,안창우,김준,Pawan K. Bhartia,Omar Torres,David Haffner,Robert J.D. Spurr,Xiong Liu,Kelly Chance,Brent N. Holben 한국기상학회 2014 한국기상학회 학술대회 논문집 Vol.2014 No.10

Validation of OMI total ozone retrievals from the SAO ozone profile algorithm and three operational algorithms with Brewer measurements

Bak, J.,Liu, X.,Kim, J. H.,Chance, K.,Haffner, D. P. Copernicus GmbH 2015 Atmospheric Chemistry and Physics Vol.15 No.2

<P>Abstract. The accuracy of total ozone computed from the Smithsonian Astrophysical Observatory (SAO) optimal estimation (OE) ozone profile algorithm (SOE) applied to the Ozone Monitoring Instrument (OMI) is assessed through comparisons with ground-based Brewer spectrometer measurements from 2005 to 2008. We also compare the three OMI operational ozone products, derived from the NASA Total Ozone Mapping Spectrometer (TOMS) algorithm, the KNMI (Royal Netherlands Meteorological Institute) differential optical absorption spectroscopy (DOAS) algorithm, and KNMI's Optimal Estimation (KOE) algorithm. The best agreement is observed between SAO and Brewer, with a mean difference of within 1% at most individual stations. The KNMI OE algorithm systematically overestimates Brewer total ozone by 2% at low and mid-latitudes and 5% at high latitudes while the TOMS and DOAS algorithms underestimate it by ~1.65% on average. Standard deviations of ~1.8% are calculated for both SOE and TOMS, but DOAS and KOE have higher values of 2.2% and 2.6%, respectively. The stability of the SOE algorithm is found to have insignificant dependence on viewing geometry, cloud parameters, or total ozone column. In comparison, the KOE-Brewer differences are significantly correlated with solar and viewing zenith angles and show significant deviations depending on cloud parameters and total ozone amount. The TOMS algorithm exhibits similar stability to SOE with respect to viewing geometry and total column ozone, but has stronger cloud parameter dependence. The dependence of DOAS on observational geometry and geophysical conditions is marginal compared to KOE, but is distinct compared to the SOE and TOMS algorithms. Comparisons of all four OMI products with Brewer show no apparent long-term drift, but seasonal features are evident, especially for KOE and TOMS. The substantial differences in the KOE vs. SOE algorithm performance cannot be sufficiently explained by the use of soft calibration (in SOE) and the use of different a priori error covariance matrices; however, other algorithm details cause fitting residuals larger by a factor of 2-3 for KOE. </P>

Evolving the Cybersecurity of Clinical Photography in Plastic Surgery

Spoer Daisy L.,Junn Alexandra,Bovill John D.,Haffner Zoë K.,Abadeer Andrew I.,Baker Stephen B. 대한성형외과학회 2023 Archives of Plastic Surgery Vol.50 No.4

Point-of-care photography and photo sharing optimize patient outcomes and facilitate remote consultation imperative for resident surgeons. This literature review and external pilot survey study highlight the risks associated with current practices concerning patient privacy and biometric security. In a survey of 30 plastic surgeon residents and attendings, we found that themajority took photos of patients with their iPhones and shared them with colleagues via Apple iMessage. These findings corroborate previous reports and highlight a lack of physician user acceptance of secure photosharing platforms. Finally, we frame a successful example from the literature in the context of a postulated framework for institutional change. Prioritizing the privacy and safety of patients requires a strategic approach that preserves the ease and frequency of use of current practices.

An optimal-estimation-based aerosol retrieval algorithm using OMI near-UV observations

Jeong, U.,Kim, J.,Ahn, C.,Torres, O.,Liu, X.,Bhartia, P. K.,Spurr, R. J. D.,Haffner, D.,Chance, K.,Holben, B. N. Copernicus GmbH 2016 Atmospheric Chemistry and Physics Vol.16 No.1

<P>Abstract. An optimal-estimation(OE)-based aerosol retrieval algorithm using the OMI (Ozone Monitoring Instrument) near-ultraviolet observation was developed in this study. The OE-based algorithm has the merit of providing useful estimates of errors simultaneously with the inversion products. Furthermore, instead of using the traditional look-up tables for inversion, it performs online radiative transfer calculations with the VLIDORT (linearized pseudo-spherical vector discrete ordinate radiative transfer code) to eliminate interpolation errors and improve stability. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved aerosol optical thickness (AOT) and single scattering albedo (SSA). The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The OE-based estimated error represented the variance of actual biases of AOT at 388 nm between the retrieval and AERONET measurements better than the operational error estimates. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface reflectance at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine-mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for relevant studies. Detailed advantages of using the OE method were described and discussed in this paper. </P>