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Ko, Jongwan,Im, Myungshin,Lee, Hyung Mok,Lee, Myung Gyoon,Kim, Seong Jin,Shim, Hyunjin,Jeon, Yiseul,Hwang, Ho Seong,Willmer, Christopher N. A.,Malkan, Matthew A.,Papovich, Casey,Weiner, Benjamin J.,Ma IOP Publishing 2012 The Astrophysical journal Vol.745 No.2
<P>We present the mid-infrared (MIR) properties of galaxies within a supercluster in the north ecliptic pole region at z similar to 0.087 observed with the AKARI satellite. We use data from the AKARI NEP-Wide (5.4 deg(2)) IR survey and the CLusters of galaxies EVoLution studies (CLEVL) mission program. We show that near-IR (3 mu m)-mid-IR (11 mu m) color can be used as an indicator of the specific star formation rate and the presence of intermediate-age stellar populations. From the MIR observations, we find that red-sequence galaxies consist not only of passively evolving red early-type galaxies, but also of (1) 'weak-SFGs' (disk-dominated star-forming galaxies that have star formation rates lower by similar to 4 x than blue-cloud galaxies) and (2) 'intermediate-MXGs' (bulge-dominated galaxies showing stronger MIR dust emission than normal red early-type galaxies). These two populations can be a set of transition galaxies from blue, star-forming, late-type galaxies evolving into red, quiescent, early-type ones. We find that the weak-SFGs are predominant at intermediate masses (10(10) M-circle dot < M-* < 10(10.5) M-circle dot) and are typically found in local densities similar to the outskirts of galaxy clusters. As much as 40% of the supercluster member galaxies in this mass range can be classified as weak-SFGs, but their proportion decreases to <10% at larger masses (M-* > 10(10.5) M-circle dot) at any galaxy density. The fraction of the intermediate-MXG among red-sequence galaxies at 10(10) M-circle dot < M-* < 10(11) M-circle dot also decreases as the density and mass increase. In particular, similar to 42% of the red-sequence galaxies with early-type morphologies are classified as intermediate-MXGs at intermediate densities. These results suggest that the star formation activity is strongly dependent on the stellar mass, but that the morphological transformation is mainly controlled by the environment.</P>
UV air disinfection respiratory viral aerosols
Christopher Walker,고광표(Gwang Pyo Ko) 대한환경공학회 2006 대한환경공학회 학술발표논문집 Vol.2006 No.12
Ultraviolet (UV) air disinfection is one of the engineering control methods utilized to control airborne transmission of pathogenic microorganisms in high risk settings. However, despite the recent emergence of respiratory viral pathogens such as SARS coronavirus and avian influenza viruses, UV air disinfection of viral aerosols is poorly studied. Hence, we characterized UV disinfection of viral aerosols using MS2, adenovirus, and coronavirus. The objectives of this study are (1) characterize the effect of nebulization and air sampling on the survival of tested viruses; (2) quantitatively estimate UV susceptibilities of these viral aerosols; (3) evaluate the effect of relative humidity (RH) on the susceptibility of viral aerosols to UV irradiation. A bench-size experimental chamber was built and evaluated for this study. MS2, adenovirus, or coronavirus was aerosolized into the experimental chamber, exposed to different UV doses, at either 50% or 75-80% RHs, and then sampled by AGI-30 liquid impinger at 12.5 LPM. The collected samples were analyzed by plaque assays to measure the UV susceptibilities of tested viral aerosols. Our data indicated that neither nebulization nor air sampling using liquid impinger caused significant inactivation of non-enveloped viruses such as MS2 or adenovirus. However, coronavirus was significantly inactivated by both nebulization and air sampling. Both MS2 and adenoviruses were very resistant to UV air disinfection. Less than 1 log reduction in viable virus was observed at the 2.6 mJ/㎠ UV dose for both viruses. However, coronavirus was more susceptible to UV air disinfection, which suggests that UV air disinfection could be an efficient environmental control method to prevent airborne transmission of novel SARS coronavirus. There was no significant protective effect of high RH on UV susceptibilities of the tested viral aerosols. Finally, our study also confirmed that UV disinfection rates of viral aerosols are much different from those of viruses suspended in water.
Christopher James Green,고종환(Ko Jong Hwan) 한국지방정부학회 2016 지방정부연구 Vol.19 No.4
한국에서 벽화문화마을이 명성을 얻고 있으며 이웃형성에 매우 중요한 부분을 차지하고 있다. 또한 문화마을을 경제개발에 활용하고자 하는 연구자들의 연구대상이 되고 있다. 본 논문에서는 문화적 편익, 문화적 비용, 문화마을을 방문하는 방문객들의 생각 등과 같은 변수를 이용하여 문화마을에 대한 경험이 문화마을의 가치를 인식하는데 어느 정도 영향을 주는 가를 정량적으로 분석하였다. 이를 위해 구조방정식모형을 활용하였는데, 이 구조방정식모형에는 문화적 편익, 문화적 비용, 경제적 편익, 방문객의 인식과 같은 잠재변수를 사용하였다. 본 연구결과에 따르면 문화마을을 방문하는 사람들이 지불하는 문화적 비용이 있음에도 불구하고 그 문화적 비용은 별로 크지 않아 문화마을에 대한 방문객의 긍정적 인식이 더 큰 것으로 분석되었다. 따라서 한국에서 재개발의 대안으로서 문화마을을 계속 활용하고 지속적으로 개발하는 것이 문화마을의 거주자에게 긍정적 외부효과를 가져다줄 것으로 판단된다. Cities have recently been trying to gain the economic benefits of visitors by creating cultural amenities to attract tourists. One cultural amenity in use in Korea for this purpose has been wall mural villages. Wall mural villages in Korea have gained fame and have become an integral part of neighborhoods, which has garnered much research by those looking to utilize them for economic development. Past research shows the creation of cultural amenities has both cultural benefits and cultural costs. This study uses a structural equation model including the constructs of cultural benefits, cultural costs and the economic benefits as latent independent variables to measure the dependent variable visitor approval when visiting wall mural villages. This research shows that despite slight negative effects of the cultural costs felt by visitors, they do not heavily outweigh the cultural benefits and economic benefits on the visitor approval of wall mural villages as a whole. The results of this research imply that continued use of and perpetuation of wall mural villages as a method of redevelopment in Korea creates a positive externality on underdeveloped and economically depressed areas within cities.
Evaluation of usefulness of smart device-based testing: a survey study of Korean medical students
Youngsup Christopher Lee,Oh Young Kwon,Ho Jin Hwang,Seok Hoon Ko 한국의학교육학회 2020 Korean journal of medical education Vol.32 No.3
Purpose: This study aims to understand the characteristics of smart device-based testing (SBT) by comparing the typical characteristics of students’ satisfaction with SBT, its usefulness, advantages, and disadvantages when compared with existing testing methods. Methods: A total of 250 students from the first to third year were selected as the final targets of the study and the questionnaire was developed by faculty members who participated in the survey from the start of the SBT. The total number of questions is 12, and the questionnaire used a 4-point scale. The data obtained were analyzed using the IBM SPSS ver. 23.0 (IBM Corp., Armonk, USA). Results: Answers to the “satisfaction with SBT” were generally negative, while answers to the “usefulness of SBT” were generally positive. There was no difference in satisfaction across gender and smart device ownership, whereas there were significant differences across years. With reference to the usefulness of SBT, students responded positively, while about the overall configuration and completeness of SBT, students responded negatively. Students also seemed to show a greater preference toward the pencil-paper test. Conclusion: On the other hand, students generally thought that SBT helped to assess medical knowledge better and was a more objective method of knowledge assessment than a pencil-paper test. We believe that students preferred the traditional paper-pencil test due to their unfamiliarity with SBT. We believe that an appropriate and careful remedy for drawbacks of the SBT will have a significant impact in the accumulation of actual clinical knowledge and in the improvement of practical skills for medical students.
Lim, Seung-Hyuk,Ko, Young-Ho,Rodriguez, Christophe,Gong, Su-Hyun,Cho, Yong-Hoon Nature Publishing Group 2016 Light, science & applications Vol.5 No.2
<P>White light-emitting diodes (LEDs) are becoming an alternative general light source, with huge energy savings compared to conventional lighting. However, white LEDs using phosphor(s) suffer from unavoidable Stokes energy converting losses, higher manufacturing cost, and reduced thermal stability. Here, we demonstrate electrically driven, phosphor-free, white LEDs based on three-dimensional gallium nitride structures with double concentric truncated hexagonal pyramids. The electroluminescence spectra are stable with varying current. The origin of the emission wavelength is studied by cathodoluminescence and high-angle annular dark field scanning transmission electron microscopy experiments. Spatial variation of the carrier injection efficiency is also investigated by a comparative analysis between spatially resolved photoluminescence and electroluminescence.</P>