• 대한화학회지
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• 제23권5호
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• pp.271-276
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• 1979

EHT 및 CNDO/2 분자궤도법을 사용하여 각종 이노시톨의 형태의 안정성을 결정하였다. EHT 계산결과는 실험사실과 일치하며 산소원자간의 비결합 1,3-상호작용을 올바르게 나타내 주었다. 또 EHT 결과에 따르면 수산기의 수소와 인접 산소간의 퍼텐셜 에너지가 형태 결정의 주요 요소의 하나임을 알 수 있었다. CNDO/2 방법은 고립쌍-고립쌍간의 불안정 요인이 되는 상호작용을 올바르게 나타내주지 못했으며 이것은 1,3-상호작용이 있는 형태의 안정도를 과도하게 나타내었다. 이노시톨의 형태연구에는 CNDO/2 방법보다 EHT 방법이 우수하다.

• 천문학회보
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• 제44권1호
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• pp.59.2-59.2
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• 2019

Event Horizon Telescope (EHT) aims to resolve the innermost region to the super massive black hole (SMBH) with its extremely high angular resolution (~20-25 uas) and enhanced sensitivity (down to 1-10 mJy) in concert with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 mm wavelength. This has a great importance as the first observational probe of the black hole shadow which has been theoretically predicted as a ring-like emission affected by the general relativistic effect under a strong gravitational field of SMBH. During the 2017 April 5-11, four nights of EHT observing campaign were carried out towards its primary targets, M87 and $SgrA{\ast}$. To robustly ensure the data processing, independent pipelines for various radio data calibration softwares (e.g., AIPS, HOPS, CASA) have been developed and cross-compared each other. The EHT has also been developing newer interferometric imaging techniques (e.g., eht-imaging-library, SMILI, dynamical imaging), as well as using an established method (CLEAN). With these, the EHT has designed various strategies which will be adopted for convincing imaging results. In this talk, I review how the robustness of EHT data processing and imaging will be validated so that the results can be ensured against well known uncertainties or biases in the interferometric data calibration and imaging.

• 천문학회보
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• 제44권1호
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• pp.59.1-59.1
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• 2019

Immediate vicinity of a supermassive black hole (SMBH) is an important place to test general relativity in strong gravity regime. Also, this is a place where mass accretion and jet formation actively occurs at the centers of active galaxies. Theoretical studies predict presence of bright ring-like emission encircling an accreting SMBH with a diameter of about 5 Schwarzschild radii, and a flux depression at the center (i.e., BH shadow). Direct imaging of the BH shadow is accordingly of great importance in modern astrophysics. However, the angular sizes of the horizon-scale structures are desperately small (e.g., ~40-50 microarcseconds (uas) diameter for the nearest best candidates). This poses serious challenges to observe them directly. Event Horizon Telescope (EHT) is a global network of sensitive radio telescopes operating at 230 GHz (1.3 mm), providing ultra-high angular resolution of 20 uas by cutting-edge very long baseline interferometry techniques. With this resolution, EHT aims to directly image the nearest SMBHs; M87 and the galactic center Sgr $A{\ast}$ (~40-50 uas diameters). In Spring 2017, the EHT collaboration conducted a global campaign of EHT and multiwavelength observations of M87 and Sgr $A{\ast}$, with addition of the phased ALMA to the 1.3mm VLBI array. In this talk, I review results from past mm-VLBI and EHT observations, provide updates on the results from the 2017 campaign, and future perspectives.

• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.761-767
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• 2022

EHT1 and EEB1 are the key Saccharomyces cerevisiae genes involved in the synthesis of ethyl esters during wine fermentation. We constructed single (Δeht1, Δeeb1) and double (Δeht1Δeeb1) heterogenous mutant strains of the industrial diploid wine yeast EC1118 by disrupting one allele of EHT1 and/or EEB1. In addition, the aromatic profile of wine produced during fermentation of simulated grape juice by these mutant strains was also analyzed. The expression levels of EHT1 and/or EEB1 in the relevant mutants were less than 50% of the wild-type strain when grown in YPD medium and simulated grape juice medium. Compared to the wild-type strain, all mutants produced lower amounts of ethyl esters in the fermented grape juice and also resulted in distinct ethyl ester profiles. ATF2, a gene involved in acetate ester synthesis, was expressed at higher levels in the EEB1 downregulation mutants compared to the wild-type and Δeht1 strains during fermentation, which was consistent with the content of acetate esters. In addition, the production of higher alcohols was also markedly affected by the decrease in EEB1 levels. Compared to EHT1, EEB1 downregulation had a greater impact on the production of acetate esters and higher alcohols, suggesting that controlling EEB1 expression could be an effective means to regulate the content of these aromatic metabolites in wine. Taken together, the synthesis of ethyl esters can be decreased by deleting one allele of EHT1 and EEB1 in the diploid EC1118 strain, which may modify the ester profile of wine more subtly compared to the complete deletion of target genes.

• 대한화학회지
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• 제21권1호
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• pp.32-37
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• 1977

EHT 분자궤도함수법 계산으로 9가지 furan, thiophene 및 pyrrole의 2-치환체의 우세한 형태를 구명하였다. 계산 결과는 furan 유도체의 우세한 형태는 trans형인데 이것은 주로 정전기적 상호작용에 의하여 안정화되어 있으며 thiophene에서는 hetero 고리의 S원자와 카르보닐 산소와의 전자적 콘쥬게이션이, 그리고 pyrrole에서는 정전기적 및 콘쥬게이션 효과가 안정한 형태를 결정하는데 작용하고 있다. EHT계산 결과는 실험결과와도 잘 일치된다.

• 한국환경과학회지
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• 제27권4호
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• pp.251-259
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• 2018

This study was conducted to determine the effects of combination of air temperature and soil water content on the growth, physiological disorder rate, and yield of hot peppers. The study was carried out in a typical plastic house (open on one side and with ventilation fans on the other side), which was maintained with gradient air temperature (maximum difference in air temperature: $6^{\circ}C$). The deficit irrigation (DI) treatment commenced 65 days after transplanting. The height of plant and fresh and dry weights of the stem increased at high air temperature (ambient + $6^{\circ}C$, extreme high temperature; EHT). Furthermore, the leaf area decreased significantly with the DI treatment. There were no significant differences in the stem diameter, number of branches, and fresh and dry weights of the leaves among all the treatments. The net photosynthesis rate of the full irrigation (FI) treatment was higher than that of the DI treatment. The photosynthesis rate at ambient air temperature was $19.7{\mu}mol\;CO_2m^{-2}{\cdot}s^{-1}$, the highest among all the treatments; however, the photosynthesis rate of the EHT treatment decreased by 60% ($12.3{\mu}mol\;CO_2m^{-2}{\cdot}s^{-1}$). Additionally, the formation of guard cells in the leaf was abnormal with the EHT treatment, and there was a decrease in translocation efficiency. The effects of air temperature treatment were more pronounced on the physiological disorder rate and yield. The physiological disorder rate of the EHT treatment was the highest under the DI treatment condition. The yield of the AFI (ambient air temperature with full irrigation) treatment was 3,771 kg/10a, the highest among all the treatments; however, the yield of the EHT treatment with DI and FI was 1,282 and 1,327 kg/10a, respectively. These results indicate that growth and physiological disorder rate improved with the EHT treatment; however, there was a decrease in yield. Furthermore, the formation of guard cells was abnormal and malfunctional.

• 대한기관식도과학회지
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• 제14권2호
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• pp.48-52
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• 2008

Ectopic Hamartomatous thymoma(EHT) is a rare benign tumor that occurs mainly in the supraclavicular or suprasternal area. Since this entity was first reported by Smith et al. in 1982, less than 50 cases have been reported in the literature. Recognition of EHT is important and needs to be differentiated from high-grade sarcomas such as synovial sarcoma or malignant peripheral nerve sheath tumor because EHT follows a benign clinical course. We experienced a case of ectopic hamartomatous thymoma in the suprasternal area in a 53-year-old man. Here, we present the case with a review of the related literatures.

• 천문학회보
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• 제44권1호
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• pp.59.3-59.3
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• 2019

Very Long Baseline Interferometry (VLBI) is a special technique which can provide high angular resolutions of milliarcsecond and sub-milliarcsecond sales in radio astronomical observations. Recently, the mm/sub-mm VLBI observations becomes more widely available and related activities are increasing accordingly. In this talk, I'll introduce ongoing global mm-VLBI activities and EHT collaboration and our (Korean) contributions to them.

• Environmental Analysis Health and Toxicology
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• 제30권sup호
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• pp.9.1-9.1
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• 2015

• Environmental Analysis Health and Toxicology
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• 제30권
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• pp.16.1-16.1
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• 2015