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Nam D.,University of California at Irvine | Hyun K.,University of California at Irvine | Kim H.,Dong - A University | Ahn K.,Seoul Institute | Jayakrishnan R.,University of California at Irvine
Transportation Research Record | Year: 2016

Understanding the spatial variation of taxi ridership is of critical importance to many government agencies and taxi companies because taxis' location dependency on spatial pattern of passenger demand results in spatially unbalanced taxi demand and supply. This study presents an analysis of the spatial distribution of taxi ridership by using large-scale GPS taxi trip data collected from Seoul, South Korea. To capture the spatial variations better in taxi ridership, GPS entities were disaggregated into units of a uniform size with a grid cell decomposition method. A geographically weighted spatial regression was applied to model spatial correlations of factors associated with transit and urban density to taxi ridership. Results from the proposed method demonstrated a higher relationship between taxi and subway ridership in the regions where lower accessibility to subway stations existed. In these regions, taxis were found to perform as a complementary mode to subway. In residential and commercial districts, this analysis showed that population and employment were highly related to taxi ridership. In contrast, in central business districts it was the building area (floor space), rather than population and employment, that was highly related to taxi ridership. © 2016, National Research Council. All rights reserved.

PubMed | Chonnam National University, National Forensic Service, West Sea Fisheries Research Institute and Seoul Institute
Type: | Journal: Forensic science international | Year: 2015

The mottled skate, Beringraja pulchra is one of the commercially important fishes in the market today. However, B. pulchra identification methods have not been well developed. The current study reports a novel real-time PCR method based on TaqMan technology developed for the genetic identification of B. pulchra. The mitochondrial cytochrome oxidase subunit 1 (COI) nucleotide sequences of 29 B. pulchra, 157 skates and rays reported in GenBank DNA database were comparatively analyzed and the COI sequences specific to B. pulchra was identified. Based on this information, a system of specific primers and Minor Groove Binding (MGB) TaqMan probe were designed. The assay successfully discriminated in 29 specimens of B. pulchra and 27 commercial samples with unknown species identity. For B. pulchra DNA, an average Threshold Cycle (Ct) value of 19.10.1 was obtained. Among 27 commercial samples, two samples showed average Ct values 19.10.0 and 26.70.1, respectively and were confirmed to be B. pulchra based on sequencing. The other samples tested showed undetectable or extremely weak signals for the target fragment, which was also consistent with the sequencing results. These results reveal that the method developed is a rapid and efficient tool to identify B. pulchra and might prevent fraud or mislabeling during the distribution of B. pulchra products.

Luong T.T.,Sungkyunkwan University | Kim E.-H.,Sungkyunkwan University | Kim E.-H.,Seoul Institute | Bak J.P.,Sungkyunkwan University | And 5 more authors.
Infection and Immunity | Year: 2015

Alcohol impairs the host immune system, rendering the host more vulnerable to infection. Therefore, alcoholics are at increased risk of acquiring serious bacterial infections caused by Streptococcus pneumoniae, including pneumonia. Nevertheless, how alcohol affects pneumococcal virulence remains unclear. Here, we showed that the S. pneumoniae type 2 D39 strain is ethanol tolerant and that alcohol upregulates alcohol dehydrogenase E (AdhE) and potentiates pneumolysin (Ply). Hemolytic activity, colonization, and virulence of S. pneumoniae, as well as host cell myeloperoxidase activity, proinflammatory cytokine secretion, and inflammation, were significantly attenuated in adhE mutant bacteria (ΔadhE strain) compared to D39 wild-type bacteria. Therefore, AdhE might act as a pneumococcal virulence factor. Moreover, in the presence of ethanol, S. pneumoniae AdhE produced acetaldehyde and NADH, which subsequently led Rex (redox-sensing transcriptional repressor) to dissociate from the adhE promoter. An increase in AdhE level under the ethanol condition conferred an increase in Ply and H2O2 levels. Consistently, S. pneumoniae D39 caused higher cytotoxicity to RAW 264.7 cells than the ΔadhE strain under the ethanol stress condition, and ethanol-fed mice (alcoholic mice) were more susceptible to infection with the D39 wild-type bacteria than with the ΔadhE strain. Taken together, these data indicate that AdhE increases Ply under the ethanol stress condition, thus potentiating pneumococcal virulence. © 2015, American Society for Microbiology.

A liquid chromatography/tandem mass spectrometry method with solid phase extraction for the detection and the quantitation of flufenoxuron in an aliquot of blood was developed and validated. Flufenoxuron belongs to a benzoylurea insecticide and is the active ingredient of Cascade. The analyte in postmortem specimens was extracted by solid-phase extraction with Bond Elut Certify cartridge. After the elution layer was evaporated, the residue was reconstituted with 70% methanol for LC/MS/MS analysis. Separations were carried out on a Synergi() 2.5u Fusion-RP 100 A column with column temperature kept at 40 C at a flow rate of 0.4 mL/min. The mobile phase was composed of 5mM ammonium formate in 10% methanol and 5 mM ammonium formate in 90% methanol using gradient elution. A triple quadruple mass spectrometer equipped with an electrospray ionization source operated in a positive ion mode with selective reaction monitoring mode. Atrazine-d5 was used as internal standard. The assay was linear over 0.02-1.0 mg/L (r(2)=0.999). Limit of detection (LOD) and limit of quantitation (LOQ) in blood were 0.009 mg/L (S/N=3) and 0.02 mg/L (S/N=10), respectively. The accuracy and the precision were <14.9% of bias% and <8.1% of CV%, which are acceptable criteria according to toxicology laboratory guidelines. Relative recoveries with 0.02, 0.1 and 1.0mg/L (in blood) were 112.3%, 101.2% and 111.0% (n=5), respectively. The developed method was applied in forensic toxicology to determine flufenoxuron in postmortem specimens in a fatal case of flufenoxuron intoxication in a 48-year-old-man who was found dead on bed in a small room after vomiting on the floor. The postmortem heart blood, peripheral blood and gastric contents were analyzed for flufenoxuron with the result of 6.3 mg/L in heart blood, 3.2 mg/L in peripheral blood and 30.6 mg/kg in gastric contents, respectively. The concentration ratio of the heart/peripheral blood of flufenoxuron was 2.0, and the ratio of gastric contents/peripheral blood was 9.4, suggesting possible postmortem redistribution and there may be a massive amount of flufenoxuron orally ingested. This case study is the first report of lethal concentrations of flufenoxuron in postmortem specimens.

PubMed | Daegu Institute, Busan Institute, Gachon University, Seoul Institute and National Forensic Service
Type: | Journal: Journal of forensic sciences | Year: 2016

This study presented a Ferris wheel accident case. A Ferris wheel is composed of many parts, and the outmost ring of it is assembled using a lock pin. This accident occurred because the lock pin caught the door of a gondola and the gondola overturned. Five of the seven passengers in the gondola fell to the ground, along with the gondolas viewing window. The investigation revealed that the gondola became stuck when its door was caught by a lock pin at the Ferris wheels three oclock position. The contact between the door and the lock pin was due to a structural problem: There was not enough space allotted between the door and the lock pin. Therefore, if a passenger pushed on the gondolas door, the potential existed for contact between the door and the lock pin.

PubMed | National Forensic Service and Seoul Institute
Type: | Journal: Legal medicine (Tokyo, Japan) | Year: 2016

The leucomalachite green (LMG) test is one of catalytic tests for the detection of latent bloodstains and generally used in forensic field because of convenience and cost/time-effectiveness. However, contamination of latent bloodstains at crime scenes can interfere with the LMG reaction, resulting in false-negative or false-positive decisions. Herein, we examined if ascorbic acid and vitamin C (l-ascorbic acid or ascorbate)-containing beverages affect the LMG reaction. Ascorbic acid showed the inhibitory activities on the LMG reaction in a dose-dependent manner. Similarly, vitamin C-containing beverages also inhibited the LMG reaction and the inhibitory effects were proportional to the concentrations of vitamin C in beverages. It was also identified that as incubation time after adding LMG reagent to the mixtures of blood and ascorbic acid or beverages was increased, the inhibitory effects of ascorbic acid vitamin C-containing beverages on LMG test were disappeared. These results suggest that the LMG reaction is delayed but not stopped by ascorbic acid and vitamin C-containing beverages. Neither incubation at room temperature around 20-25C nor the addition of acetic acid affects the inhibitory activity of ascorbic acid on LMG reaction. We also showed that ascorbic acid does not affect DNA stability, allowing us to obtain full short tandem repeat (STR) profiles through amplification of DNA using commercial STR kits. In conclusion, ascorbic acid and vitamin C-containing beverages delayed the LMG reaction, suggesting that it should be considered that negative results of LMG test could be false negative due to contamination of bloodstains with inhibitory factors on LMG test.

Jang W.,University of Seoul | Clark T.N.,University of Chicago | Byun M.,Seoul Institute
Research in Urban Policy | Year: 2014

As noted in this volume's introduction, Bohemia is considered a core component driving innovation and urban development in the West. From Balzac through Richard Florida, Bohemians are creative. Artists are the quintessence in the sense that breaking the eggs of tradition is a prerequisite to cooking a new omelet. The core idea seems broadly accepted by many readers and commentators in the United States and Western Europe. However, many Korean intellectuals react with puzzlement when asked what or where is the local Bohemia. Many imply that there are none in most Asian countries. There is evidence for this argument. Korean university students seem to dress more elegantly than Westerners. Many female students often wear skirts or dresses and high-heeled shoes and make up to class. Regarding tolerance of homosexuals, there is a famous story about a television star who came out with his gay identity and was fired from his job. Dressing inelegantly and tolerating gays are two possible indicators of Bohemia that Richard Florida has stressed, but a critical point to reassess is whether the idea of Bohemia should be revised or whether a new concept should be considered as Asian variations are more specifically incorporated into international theory. This chapter will examine whether or not Bohemia is absent using scene data. The results will also be compared with those from Chicago to lead to incorporate Asian variations more specifically. Copyright © 2014 by Emerald Group Publishing Limited.

Jang W.,University of Seoul | Clark T.N.,University of Chicago | Byun M.,Seoul Institute
Research in Urban Policy | Year: 2014

In this chapter, we review how scenes theory can be related to civic participation and how the relationship differs across Seoul, Tokyo, and Chicago. The discussion begins with the major Western theory of Tocqueville/Putnam that participation drives legitimacy. However, it can be briefly relativized by introducing alternative paths. These ideas link to results from Kim (Kim, S. 2008) that show different paths for legitimacy and trust according to different political development and different cultural structure in the society. As shown in Fig. 1 of Chapter 2, most of Northwest Europe and North America supports Model 1: more participation leads to more trust. Obversely, Latin Americans have such low participation and trust that even if participation works for a few it misses the great majority. However, the model grows more complex when we shift to Korea, Portugal, and Eastern Europe, as the participation to trust path coefficient falls to zero: no impact. For some subgroups, the coefficient even becomes negative (Model 4). How can we codify these results and link them to our cumulative theorizing? This question cannot be answered with a simplistic generalization. Instead, we need to introduce a different conceptual framing to ask where and why and how much this happens. In this chapter, we try to suggest various propositions to explain differences in civic participation in the three cities by using various concepts related to scenes. Copyright © 2014 by Emerald Group Publishing Limited.

Benschop C.C.G.,Netherlands Forensic Institute | Yoo S.Y.,Seoul Institute | Sijen T.,Netherlands Forensic Institute
Forensic Science International: Genetics Supplement Series | Year: 2015

We assessed various approaches for DNA profiling using the same total amount of DNA. The choice of profiling approach affects genotyping success and may in addition affect the likelihood ratio (LR). © 2015 Elsevier Ireland Ltd.

Ko J.,Seoul Institute
ITE Journal (Institute of Transportation Engineers) | Year: 2013

The article examines vehicle trip generation rates for office buildings in Seoul, South Korea, one of the densest cities where transit systems and employer-based travel demand management (TDM) programs are well established. Seoul has been implementing a variety of TDM measures, including a voluntary weekly no-driving day program, congestion pricing, and parking caps. One such measure is an employer-based TDM composed of 19 programs, including parking regulations, vehicle number plate rationing programs, commuter bus operations, and carpool options. Data on site characteristics were collected for the sampled buildings. The data included floor area, numbers of parking spaces and employees, location, distances to the nearest subway station and bus stop, numbers of subway stations within 300 m and 500 m, and numbers of bus stops and lines within 300 m.

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