DISCOVERY OF A FAINT QUASAR AT <i>z</i> ∼ 6 AND IMPLICATIONS FOR COSMIC REIONIZATION

Kim, Yongjung,Im, Myungshin,Jeon, Yiseul,Kim, Minjin,Choi, Changsu,Hong, Jueun,Hyun, Minhee,Jun, Hyunsung David,Karouzos, Marios,Kim, Dohyeong,Kim, Duho,Kim, Jae-Woo,Kim, Ji Hoon,Lee, Seong-Kook,Pak, IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.813 No.2

<P>Recent studies suggest that faint active galactic nuclei may be responsible for the reionization of the universe. Confirmation of this scenario requires spectroscopic identification of faint quasars (M-1450 > -24 mag) at z greater than or similar to 6, but only a very small number of such quasars have been spectroscopically identified so far. Here, we report the discovery of a faint quasar IMS J220417.92+011144.8 at z similar to 6 in a 12.5 deg(2) region of the SA22 field of the Infrared Medium-deep Survey (IMS). The spectrum of the quasar shows a sharp break at similar to 8443 angstrom, with emission lines redshifted to z = 5.944 +/- 0.002 and rest-frame ultraviolet continuum magnitude M-1450 = -23.59 +/- 0.10 AB mag. The discovery of IMS J220417.92+011144.8 is consistent with the expected number of quasars at z similar to 6 estimated from quasar luminosity functions based on previous observations of spectroscopically identified low-luminosity quasars. This suggests that the number of M-1450 similar to 23 mag quasars at z similar to 6 may not be high enough to fully account for the reionization of the universe. In addition, our study demonstrates that faint quasars in the early universe can be identified effectively with a moderately wide and deep near-infrared survey such as the IMS.</P>

석면관련 폐질환의 진단에 있어서 흉부고해상도전산화단층촬영검사(HRCT)의 유용성

이현재,손지언,,홍영습,,이영일,예병진,유창훈,정갑열,김상훈,임형준,장은철,김정만,김준연 大韓産業醫學會 2006 대한직업환경의학회지 Vol.18 No.2

목적: 석면에 노출된 근로자에서 석면관련 폐질환의 양상을 분석하고 진단에 있어 HRCT의 유용성을 연구하여 석면에 대한 의학적 감시프로그램의 개발에 기여하고자 하였다. 방법: 석면에 직접 노출되는 작업자 68명과 간접 노출되는 작업자 94명 등 총 162명에 대해 OSHA 석면 표준, 의학적 감시 프로그램에 따라 단순 흉부방사선검사, 폐활량검사 및 우리나라 실정에 맞게 일부 수정한 의학적 설문지를 통해 면접조사의 방식으로 환자에 관한 정보를 수집하였으며, 자료의 신뢰성을 확보하기 위하여 면접조사는 1달 이상의 기간을 두고 2차례에 걸쳐 실시된 후 확인, 수정하였다. 또한, 석면관련 폐질환을 확진하기 위하여 HRCT를 추가적으로 실시하였다. 결과: HRCT결과 석면관련 폐질환의 유병율은 162명의 근로자중 17명으로 10.5%였는데, 직접 노출군에서 10명 (14.7%), 간접 노출군에서 7명 (7.4%)이었다. HRCT와 비교할 때 단순 흉부방사선검사의 민감도와 특이도는 각각 70.6%와 98.6%이었고, 양성 예측도와 음성 예측도는 각각 85.7%와 96.6%으로, HRCT는 단순흉부방사선검사에 비해 민감도가 높아 초기 석면관련 폐질환을 진단하는데 효과적이었다. 석면관련 폐질환의 진단에 있어 HRCT와 폐활량검사 사이에 유의한 관련성이 관찰되었다. HRCT 결과 석면관련 폐질환의 유무와 의학적 설문조사 결과의 빈도분석을 실시한 결과, 유의한 변수는 작업기간, 흡연량, 호흡기질환의 과거력, 기침, 호흡곤란이었다. 결론: HRCT는 석면관련 폐질환의 진단에 있어 단순 흉부방사선검사와 비교하여 민감도가 높아 초기 진단에 유용하므로 단순 흉부방사선선검사 결과 석면관련 폐질환소견을 보일 때뿐만 아니라, 정상소견을 보이더라도 폐활량 검사결과와 근무력, 흡연력, 호흡기질환의 과거력, 기침, 호흡곤란 등의 호흡기 증상을 참고하여 HRCT검사를 고려해야 한다. 또한, 본 연구에서 관련성이 없었던 요인들에 대해서도 향후 연관성을 규명하는 광범위한 전향적 연구가 필요하다. Objectives: This study was carried out to improve the medical surveillance program of workers exposed to asbestos by examining the usefulness of High Resolution Computed Tomography (HRCT) in the diagnosis of asbestos-related lung disease. Methods: The study subjects comprised 162 workers in a ship-repairing yard, 68 of whom had been directly exposed to asbestos and 94 indirectly exposed. The 'Occupational Safety & Health Administration (OSHA) asbestos standard, medical surveilance program' and HRCT were conducted to analyze the aspects of the asbestos-related lung disease. The OSHA asbestos standard, medical surveilance program consists of simple chest x-ray, spirometry and medical questionnarie. Results: Seventeen (10.5%) of the 162 subjects, 10 (14.7%) directly exposed and 7 (7.4%) indirectly exposed, revealed asbestos-related lung disease on HRCT. The sensitivity and specificity of simple chest x-ray for asbestos-related lung disease were 70.6% and 98.6%, and the positive and negative predictive values were 85.7% and 96.6% respectively, as compared with HRCT, HRCT was an effective diagnostic tool especially to detect early asbestos-related lung disease. The study results indicated a relative significant association between the results of spirometry and HRCT. The variables significantly associated with asbestos-related lung disease on HRCT were work duration, smoking history (pack-years), past history of respiratory disease, cough and dyspnea. Conclusions: In the diagnosis of asbestos-related lung disease, HRCT should be considered not only for workers with positive findings on simple chest x-ray, but also workers with specific findings on spirometry, occupational history, smoking history, and past history of respiratory disease, or with respiratory symptoms such as cough and dyspnea.

서울의 Penicillinase Producing Neisseria Gonorrhoeae 발생빈도(1996)

김재홍,황동규,전재홍,김윤석,김중환,김용준,이창균,임동진,김현수,조창근,김경문,박상훈,전우형,김희성,이호정,차명수,김갑형,김형석,김석우,황지환,박병순,권오상,이민수,송기훈,성소영,이인섭,부태성 대한화학요법학회 1999 대한화학요법학회지 Vol.17 No.2

Background : In recent years, gonorrhea has been panedemic and remains one of the most commom STDs in the world, especially in developing countries. Objective & Methods: For the detection of a more effective therapeutic regimen and assessing the prevalence of PPNG, we have been trying to study the patients who have visited the VD Clinic of Choong-Ku Public Health Center in Seoul since 1980 by means of the chromogenic cephalosporin method. Results: In 1996, 139 strains of N. gonorrhoeae were isolated, among which 53(39.0%) were PPNG. Conclusion: Our results suggests that after a peak of 74.3% in 1993, the prevalence of PPNG in Seoul is gradually declining.

Analysis and Compensation of PCC Voltage Variations caused by Wind Turbine Power Fluctuations

Ji-Hoon Im,Seung-Ho Song,San Kang 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5

The voltage variation problem at the point of common coupling (PCC) in a grid-connected wind turbine is investigated. The voltage variation problem is one of the most frequent power quality issues for the grid connection of large amounts of input power in a weak grid. Through the simplified modeling of the wind turbine and power network, the magnitude of PCC voltage variation is calculated by using the equivalent circuit parameters and output power of the wind turbine. The required amount of reactive power that can compensate the voltage variation is also presented analytically by using the vector diagram method. The proposed calculation and compensation method of the PCC voltage variation is verified by computer simulations and experiments.

Morphological and cultivational characteristics of a new Flammulina veluptipes variety ‘Baekseung’

Ji-Hoon Im,Sung-I Woo,Pyung-Gyun Shin,Youn-Lee Oh,Minji Oh,Won-sik Kong,Kab-Yeul Jang 한국버섯학회 2017 버섯 Vol.21 No.1

‘Baekseung’, a new variety of Flammulina velutipes, was bred by mating two monokaryotic strains isolated from KMCC 4210 and KMCC 4216 in Mushroom Research Division, Baekseung ARES in 2016. Baekseung showed fast mycelial growth and high mycelial density on MEA (Malt Extract Agar) media for 7days of incubation. Spawn running period on the sawdust substrate required 30days at 25°C. The cultivation period and optimum temperature were 11±1 days at 14°C for primordia formation and 14±1 days at 7°C for fruiting body development. The length of pilei and stipes in Baekseung harvested in optimal stage exhibited 11.3±0.4㎜ and 89.2±7.1㎜ and Megumi harvested in optimal stage showed 8.2±1.0㎜ and 95.9±5.0㎜ respectively. Yield of Baekseung and Megumi strain grown of sawdust substrate was 153.7±12.5g and 150.5±29.7g per 850ml in bottle cultivation. The inferred tree exhibited the difference of phylogenetic relationship between the Korean white fruiting body strains such as Baekseung, Uri1ho, Fv-14-a-38, and Fv-14-a-51 and the Japanese white fruiting body strain Megumi.

A Study on the Generation of Critical Scenario Dataset Based on Game Engine

Ji-Ung Im,Sang-Hoon Ahn,Jin-Gyu Ahn,Jong-Hoon Won 한국차세대컴퓨팅학회 2022 한국차세대컴퓨팅학회 학술대회 Vol.2022 No.10

Autonomous driving algorithm aims to safely control the vehicle through recognition of the surrounding environment and relevant decision and control based on deep learning algorithms. However, the deep learning algorithms require appropriate datasets but many difficulties exist in generating proper datasets for critical scenarios, e.g. accident avoidance. This paper presents a method for generating datasets for critical scenarios via a game engine. The video game engine used in this paper offers an open world environment, providing realistic graphics. A variety of non-player characters in the game equipped with a high level of Artificial Intelligence (AI) are ideally suited for the reproduction of various unexpected situations in reality by the interaction between the AIs. Using this, this paper creates a high-level critical scenario dataset and presents an augmentation method for the generated dataset.

Maintaining PCC Voltage in a Distributed Generation System Even during Power Output Fluctuation and Unbalanced Voltage Conditions

Ji-Hoon Im,Seung-Ho Song,Chan-Sol Park 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes a new PCC voltage control algorithm for DG which takes advantage of maintaining the PCC voltage regardless of whether DG outputs an active power or not. In this method, even during unbalanced voltage conditions of the PCC voltage, DG plays the role for compensating the PCC voltage. DG uses a reactive current for keeping the PCC voltage within a normal range and a negative sequence current for reducing the PCC voltage unbalance. The proposed method is verified by the PSIM simulation and experimental results.

Analysis and Compensation of PCC Voltage Variations caused by Wind Turbine Power Fluctuations

Im, Ji-Hoon,Song, Seung-Ho,Kang, San The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5

The voltage variation problem at the point of common coupling (PCC) in a grid-connected wind turbine is investigated. The voltage variation problem is one of the most frequent power quality issues for the grid connection of large amounts of input power in a weak grid. Through the simplified modeling of the wind turbine and power network, the magnitude of PCC voltage variation is calculated by using the equivalent circuit parameters and output power of the wind turbine. The required amount of reactive power that can compensate the voltage variation is also presented analytically by using the vector diagram method. The proposed calculation and compensation method of the PCC voltage variation is verified by computer simulations and experiments.

PⅢ-5 Morphological characteristics of a new Flammulina veluptipes variety ‘Baeke’

Ji-Hoon Im,Youn-Lee Oh,Minji Oh,Seul-ki Lee,Kab-Yeul Jang,Won-sik Kong 한국버섯학회 2018 버섯 Vol.22 No.1

Reactive Power Control Strategy for Inverter-based Distributed Generation System with a Programmable Limit of the Voltage Variation at PCC

Ji-Hoon Im,San Kang,Seung-Ho Song(송승호),Seung-Ki Jung,Ju-Yeop Choi,Ick Choy 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In a grid connected distributed generator, the voltage variation problem at the point of common coupling(PCC) is investigated. This is one of the most frequent power quality issues for the grid connection of large amount of the input power into a weak grid. Through a simplified modeling of the distributed generator and the power network, the magnitude of PCC voltage variation is calculated using the equivalent circuit parameters and the output power of the distributed generator. In addition, the required amount of reactive power which can compensate the voltage variation is presented analytically using a vector diagram method. With the proposed compensation method in a power conditioning system(PCS) for a distributed generation, the PCC voltage variation can be minimized automatically even though the power fluctuation occurs due to the change of input power. The proposed method of the calculation and compensation of the PCC voltage variation is verified by computer simulation and experimental results.