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Free-fall energy density and flux in the Schwarzschild black hole
Kim, Wontae,Majhi, Bibhas Ranjan World Scientific Publishing Company 2015 International journal of modern physics. A, Partic Vol.30 No.11
<P>In the four-dimensional background of Schwarzschild black hole, we investigate the energy densities and fluxes in the freely falling frames for the Boulware, Unruh, and Israel-Hartle-Hawking states. In particular, we study their behaviors near the horizon and asymptotic spatial infinity by using the trace anomaly of a conformally invariant scalar field. In the Boulware state, both the energy density and flux are negative divergent when the observer is dropped at the horizon, and asymptotically vanish. In the Unruh state, the energy density is also negative divergent at the horizon while it is positive finite asymptotically. The flux in the Unruh state is always positive and divergent at the horizon. In the Israel-Hartle-Hawking state, the energy density depends on the angular motion of free fall, and fluxes vanish at the horizon and the spatial infinity. Finally, we discuss the role of the negative energy density near the horizon in the evaporating black hole.</P>
Freely falling observer and black hole radiation
Kim, Wontae,Son, Edwin J. World Scientific 2014 Modern Physics Letters A Vol.29 No.11
<P> We find radiation in an infalling frame and present an explicit analytic evidence of the failure of no drama condition by showing that an infalling observer finds an infinite negative energy density at the event horizon. The negative and positive energy density regions are divided by the newly defined zero-energy curve (ZEC). The evaporating black hole is surrounded by the negative energy which can also be observed in the infalling frame. </P>
( Kim Bora ),( Lim Serah ),( Hong Wontae ),( Kim Heejung ) 정신간호학회 2019 정신간호학회지 Vol.28 No.3
Purpose: The purpose of this study was to examine mediating effects of pleasurable activities on the relationship between depression and suicidal ideation among the elderly moderated by living arrangement such as those living alone (LA) versus those living with others (LWO). Methods: This study is a cross-sectional and correlational design using secondary data analysis of the 2017 Korean National Survey on the Elderly (2,416 for the LA group, and 6,106 for the LWO group). Logistic regression analysis was conducted comparing effects of pleasurable activities on suicidal ideation between the two groups. Results: For suicidal ideation, there were significant differences in suicidal ideation by sex, religion, and senior center visits in the LA group, while the LWO group had no significant differences identified. Both groups showed significantly different associations of suicidal ideation by socioeconomic status, gathering, meaningful interaction, and depression. Senior center visits were statistically significant in the LA group, while there was not significant in the LWO group. Conclusion: Visiting senior centers can reduce suicidal ideation of the LA group. To prevent suicidal ideation of the elderly living alone, mental health specialists should provide community-cooperative environments to address these issues, especially LA elderly.
3D Inspection by Registration of CT and Dual X-ray Images
Kim, Youngjun,Kim, Wontae,Lee, Deukhee International Society for Simulation Surgery 2016 Journal of International Society for Simulation Su Vol.3 No.1
Computed tomography (CT) can completely digitize the interior and the exterior of nearly any object without any destruction. Generally, the resolution for industrial CT is below a few microns. The industrial CT scanning, however, has a limitation because it requires long measuring and processing time. Whereas, 2D X-ray imaging is fast. In this paper, we propose a novel concept of 3D non-destructive inspection technique using the advantages of both micro-CT and dual X-ray images. After registering the master object’s CT data and the sample objects’ dual X-ray images, 3D non-destructive inspection is possible by analyzing the matching results. Calculation for the registration is accelerated by parallel computing using graphics processing unit (GPU).
Thermodynamics of warped AdS<sub>3</sub> black hole in the brick wall method
Kim, Wontae,Son, Edwin J. Elsevier 2009 Physics letters: B Vol.673 No.1
<P><B>Abstract</B></P><P>The statistical entropy of a scalar field on the warped AdS<SUB>3</SUB> black hole in the cosmological topologically massive gravity is calculated based on the brick-wall method, which is different from the Wald's entropy formula giving the modified area law due to the higher-derivative corrections in that the entropy still satisfies the area law. It means that the entropy for scalar excitations on this background is independent of higher-order derivative terms or the conventional brick wall method has some limitations to take into account the higher-derivative terms.</P>
Outcome of total proctocolectomy with ileal pouch - anal anastomosis for ulcerative colitis
Wontae Cho,Yong Beom Cho,Jin Yong Kim,Dong Kyung Chang,Young-Ho Kim,Hee Cheol Kim,Seong Hyeon Yun,Woo Yong Lee,Ho-Kyung Chun 대한외과학회 2012 Annals of Surgical Treatment and Research(ASRT) Vol.83 No.3
Purpose: We evaluated the risk factors for late complications and functional outcome after total proctocolectomy (TPC) with ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC). Methods: Pre- and postoperative clinical status and follow- up data were obtained for 55 patients who underwent TPC with IPAA between 1999 and 2010. The median follow-up duration was 4.17 years. Late complications were defined as those that appeared at least one month after surgery. For a functional assessment, telephone interviews were conducted using the Global Assessment of Functioning Scale. Twenty-eight patients completed the interview. Results: Late complications were found in 20 cases (36.3%), comprising pouchitis (n = 8), bowel obstruction (n = 5), ileitis (n = 3), pouch associated fistula (n = 2), and intra-abdominal infection (n = 2). The preoperative serum albumin level for patients with late complications was lower than for patients without (2.4 ± 0.5 vs. 2.9 ± 0.7, P = 0.04). Functional outcomes were not significantly associated with clinical characteristics, follow-up duration, operation indication, or late complications. Conclusion: This study demonstrated that a low preoperative albumin level could be a risk factor for late complications of TPC with IPAA. Preoperative nutritional support, especially albumin, could reduce late complications. Functional outcomes are not related to late complications.