Seung-Hoon Yoo

Role of Water Utility in the Korean National Economy

The twin water crises in terms of both quantity and quality clearly demand that researchers provide policy makers with available and responsible information regarding the role of water utility. This paper employs input-output (I-O) analysis to examine the role of water utility in the national economy, using a specific application to Korea. A static I-O framework is employed, focusing on three topics in its application: the impacts of water supply investments and the inter-industry linkage effect, the water supply shortage costs, and the impacts of the rise in water rates. In addition, potential uses of the results are illustrated from the perspective of policy instruments. The overall results indicate that water supply investment and water shortage have a big influence on the standard of living and industrial production, but raising water rates in order to encourage conservation or to create investment funds has a minor effect on general price levels.

Shortcut-JFS: A write efficient journaling file system for phase change memory

Journaling file systems are widely used in modern computer systems as it provides high reliability with reasonable performance. However, existing journaling file systems are not efficient for emerging PCM (Phase Change Memory) storage. Specifically, a large amount of write operations performed by journaling incur serious performance degradation of PCM storage as it has long write latency. In this paper, we present a new journaling file system for PCM, called Shortcut-JFS, that reduces write amount of journaling by more than a half exploiting the byte-accessibility of PCM. Specifically, Shortcut-JFS performs two novel schemes, 1) differential logging that performs journaling only for modified bytes and 2) in-place checkpointing that removes unnecessary block copy overhead. We implemented Shortcut-JFS on Linux 2.6, and measured the performance of Shortcut-JFS and legacy journaling schemes used in ext 3. The results show that the performance improvement of Shortcut-JFS against ext 3 is 40% on average.

Dealing with zero response data from contingent valuation surveys: application of least absolute deviations estimator

Data on willingness-to-pay (WTP) collected from contingent valuation surveys are usuallycensoredat zero. Insuch cases, ordinary least squares estimationof the WTP equation produces inconsistent parameter estimates. The maximum likelihood estimation of the Tobit model, which is widely used in this case, is not robust to heteroscedasticity and non-normal error structure. A least absolute deviations estimator allows for the censored data structure and is robust to these problems. In addition, the technique is useful in the case of small amounts of data. It is applied to household survey data in which the contingent valuation question involved the benefit of greenhouse gases reduction policy in Korea.

Scaling Transition in Earthquake Sources: A Possible Link Between Seismic and Laboratory Measurements

We estimate the corner frequencies of 20 crustal seismic events from mainshock–aftershock sequences in different tectonic environments (mainshocks 5.7xa0<xa0MWxa0<xa07.6) using the well-established seismic coda ratio technique (Mayedaet al. in Geophys Res Lett 34:L11303, 2007; Mayeda and Malagnini in Geophys Res Lett, 2010), which provides optimal stability and does not require path or site corrections. For each sequence, we assumed the Brune source model and estimated all the events’ corner frequencies and associated apparent stresses following the MDAC spectral formulation of Walter and Taylor (A revised magnitude and distance amplitude correction (MDAC2) procedure for regional seismic discriminants, 2001), which allows for the possibility of non-self-similar source scaling. Within each sequence, we observe a systematic deviation from the self-similar

Dealing with bottled water expenditures data with zero observations: a semiparametric specification

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Coda-Derived Source Parameters of Earthquakes and Their Scaling Relationships in the Korean Peninsula

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SwiftTuna: Responsive and incremental visual exploration of large-scale multidimensional data

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