• 천문학회보
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• 제42권2호
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• pp.79.2-79.2
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• 2017

To dynamically and chemically understand how filaments, dense cores, and stars form under different environments, we are conducting a systematic mapping survey of nearby molecular clouds using the TRAO 14 m telescope with high ($N_2H^+$ 1-0, $HCO^+$ 1-0, SO 32-21, and $NH_2D$ v=1-0) and low ($^{13}CO$ 1-0, $C^{18}O$ 1-0) density tracers. The goals of this survey are to obtain the velocity distribution of low dense filaments and their dense cores for the study of their origin of the formation, to understand whether the dense cores form from any radial accretion or inward motions toward dense cores from their surrounding filaments, and to study the chemical differentiation of the filaments and the dense cores. Until the 2017A season, the real OTF observation time is ~760 hours. We have almost completed mapping observation with four molecular lines ($^{13}CO$ 1-0, $C^{18}O$ 1-0, $N_2H^+$ 1-0, and $HCO^+$ 1-0) on the six regions of molecular clouds (L1251 of Cepheus, Perseus West, Polaris South, BISTRO region of Serpens, California, and Orion B). The cube data for $^3CO$ and $C^{18}O$ lines were obtained for a total of 6 targets, 57 tiles, 676 maps, and $7.1deg^2$. And $N_2H^+$ and $HCO^+$ data were added for $2.2deg^2$ of dense regions. All OTF data were regridded to a cell size of 44 by 44 arcseconds. The $^{13}CO$ and $C^{18}O$ data show the RMS noise level of about (0.1-0.2) K and $N_2H^+$ and $HCO^+$ data show about (0.07-0.2) K at the velocity resolution of 0.06 km/s. Additional observations will be made on some regions that have not reached the noise level for analysis. To identify filaments, we are using and testing programs (DisPerSE, Dendrogram, FIVE) and visual inspection for 3D image of cube data. A basic analysis of the physical and chemical properties of each filament is underway.

• 천문학회지
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• 제52권1호
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• pp.23-30
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• 2019

The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving mode is demonstrated to be promising for mm-VLBI observations. Recently, other Very long baseline interferometry (VLBI) facilities all over the globe start to implement compatible optics systems. Simultaneous dual/multi-frequency VLBI observations at mm wavelengths with international baselines are thus possible. In this paper, we present the results from the first successful simultaneous 22/43 GHz dual-frequency observation with KaVA(KVN and VERA array), including images and astrometric results. Our analysis shows that the newly implemented simultaneous receiving system has brought a significant extension of the coherence time of the 43 GHz visibility phases along the international baselines. The astrometric results obtained with KaVA are consistent with those obtained with the independent analysis of the KVN data. Our results thus confirm the good performance of the simultaneous receiving systems for the nonKVN stations. Future simultaneous observations with more global stations bring even higher sensitivity and micro-arcsecond level astrometric measurements of the targets.

• Journal of Astronomy and Space Sciences
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• 제30권3호
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• pp.193-206
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• 2013

The detector subsystem of the Optical Wide-field Patrol (OWL) network efficiently acquires the position and time information of moving objects such as artificial satellites through its chopper system, which consists of 4 blades in front of the CCD camera. Using this system, it is possible to get more position data with the same exposure time by changing the streaks of the moving objects into many pieces with the fast rotating blades during sidereal tracking. At the same time, the time data from the rotating chopper can be acquired by the time tagger connected to the photo diode. To analyze the orbits of the targets detected in the image data of such a system, a sequential procedure of determining the positions of separated streak lines was developed that involved calculating the World Coordinate System (WCS) solution to transform the positions into equatorial coordinate systems, and finally combining the time log records from the time tagger with the transformed position data. We introduce this procedure and the preliminary results of the application of this procedure to the test observation images.

• 한국환경보건학회지
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• 제38권2호
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• pp.166-174
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• 2012

Introduction: After 17 years since the first production of humidifier disinfectants in Korea, Korea Centers for Disease Control and Prevention (KCDC) announced that the odds ratio of lung injury related with humidifier disinfectant usage was 47.3 (95% confidence interval 6.0-369.7) according to a case-control study with 18 adult cases, including 8 pregnant women at a university hospital in Seoul. Results: From September 2011 to April 2012, one-hundred and seventy four victim cases have been reported to an environmental non-governmental group (NGO). We summarized timetable of humidifier disinfectants accidents, analyzed health outcomes (death, lung or lung and heart transplantation, pulmonary disease) of reported victims, and classified some information for humidifier disinfectants with health outcomes, and government action for this accident. Among the victims, number of death cases are 52 (30.0%), including 26 babies less than 3 years old. Sixty-nine victims come from twenty-seven family with 2 to 4 members per family. About twenty types of humidifier disinfectant products and about 600,000 product items a year have been sold. Fifty-two death cases used 7 different types of disinfectant products, including imported goods and some private brands of well-known supermarkets. KCDC confirmed inhalation toxicity of 6 products through an animal experimental test, and based on this observation recalled disinfectants containing PHMG (polyhexamethylene guanidine) and PGH (Oligo(2-(2-ethoxy)ethoxyethyl guanidinium chloride). Discussions: The use of these biocides involved highly fatal consequences among biologically vulnerable victims, such as pregnant women, several family member victims after semi-acute exposure. This is the first biocide disaster in Korea with non-specific targets, and unknown scale of victims, warranting concerns on use of biocides in the living environment. Conclusions: Special administrative agency for chemical safety and compensation act for environmental health victims are needed to prevent similar problems.

• 한국콘텐츠학회논문지
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• 제9권1호
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• pp.455-464
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• 2009

영어 마찰음을 발음하기 어려운 점은 잘 알려졌는데, 한국 대학생들이 마찰음을 포함하는 영어 순자음을 인지하는데도 마찬가지로 어려움을 느끼는지 알아보기 위하여 40명의 한국 대학생들을 대상으로 영어 순자음이 들어간 임시어를 4가지 다른 운율적 위치(초성, 종성, 강세 앞 모음사이, 강세 뒤 모음사이)에서 인지하는 테스트를 실행하였다. 실험 참가자들은 초성이나 강세 앞 모음사이처럼 강한 위치의 자음을 종성이나 강세 뒤 모음사이의 약한 위치보다 더 정확하게 판별하는 인지패턴을 보여주었다. 한국 학생들의 인지의 어려움은 모든 운율 위치에서 영어 목표자음의 조음방법 혼동 때문에 대부분 발생하였다. 그밖에, 조음장소와 유무성의 혼동도 일어났는데, 조음장소의 혼동은 모든 운율 위치에서 주로 [f]의 음향적 속성 때문에 일어났으며 유무성의 혼동은 운율 위치의 영향 때문에 발생하였다. 이러한 조음방법, 조음장소, 유무성의 혼동은 목표자음의 음성적 속성 그리고/또는 피실험자의 모국어 속성으로 설명되었다.

• The Korean Journal of Physiology and Pharmacology
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• 제16권2호
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• pp.145-151
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• 2012

In the present work, we studied the structure-activity relationship (SAR) of tautomycetin (TMC) and its derivatives. Further, we demonstrated the correlation between the immunosuppressive fuction, anticancer activity and protein phosphatase type 1 (PP1) inhibition of TMC and its derivatives. We have prepared some TMC derivatives via combinatorial biosynthesis, isolation from fermentation broth or chemical degradation of TMC. We found that the immunosuppressive activity was correlated with anticancer activity for TMC and its analog compounds, indicating that TMC may home at the same targets for its immunosuppressive and anticancer activities. Interestingly, TMC-F1, TMC-D1 and TMC-D2 all retained significant, albeit reduced PP1 inhibitory activity compared to TMC. However, only TMC-D2 showed immunosuppressive and anticancer activities in studies carried out in cell lines. Moreover, TMC-Chain did not show any significant inhibitory activity towards PP1 but showed strong growth inhibitory effect. This observation implicates that the maleic anhydride moiety of TMC is critical for its phosphatase inhibitory activity whereas the C1-C18 moiety of TMC is essential for the inhibition of tumor cell proliferation. Furthermore, we measured $in$ $vivo$ phosphatase activities of PP1 in MCF-7 cell extracts treated with TMC and its related compounds, and the results indicate that the cytotoxicity of TMC doesn't correlate with its $in$ $vivo$ PP1 inhibition activity. Taken together, our study suggests that the immunosuppressive and anticancer activities of TMC are not due to the inhibition of PP1. Our results provide a novel insight for the elucidation of the underlying molecular mechanisms of TMC's important biological functions.

• 대한원격탐사학회지
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• 제27권5호
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• pp.587-599
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• 2011

NIIRS(National Imagery Interpretability Rating Scale)는 영상의 판독력을 설명하는 품질 지표로 고해상도 위성영상의 품질을 나타내는데 널리 사용되어 왔다. 이는 MTF(Modulation Transfer Function), SNR(Signal to Noise Ratio), 또는 GSD(Ground Sampling Distance)와는 달리 객관적이고, 직관적으로 영상의 전반적인 품질을 설명할 수 있다는 점에서, 그 활용도가 매우 크다고 할 수 있다. NIIRS는 전문 판독가에 의해 육안으로 직접 측정되거나, 영상의 에지 분석(Edge analysis)을 통해 정확하게 추정할 수 있다. 일반적으로 에지 분석에는 품질 측정을 위해 특별히 제작된 인공의 표적이 사용된다. 이 인공표적의 일례로 특정 크기의 반사율 차이를 가지는 흑백 패턴의 천막 형태가 있으며, 이러한 인공표적은 인공위성의 촬영경로 상에 설치되어 진다. 이 때문에 인공표적을 이용하는 방식은 표적의 설치와 관련하여 많은 비용이 지출될 뿐 아니라, 수시로 수행될 수 없다는 문제점을 가지게 된다. 이에 본 논문에서는 영상에서 쉽게 관측될 수 있는 자연표적들로부터 정확한 NIIRS 추정이 가능한 새로운 방식의 에지 분석법을 제안하였다. 이 방법은 임의의 성질을 가지는 자연표적의 특성을 반영하기 위해 알고리즘의 강인성이 강조되었으며, 다양한 실험들을 통해 성능이 평가되었다. 실험 결과는 제안 알고리즘이 기존 방식의 대안으로서 충분히 활용 가능함을 보여 주었다.

• 천문학회지
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• 제48권3호
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• pp.177-185
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• 2015

We develop a new auto-guiding system for the Camera for QUasars in the EArly uNiverse (CQUEAN). CQUEAN is an optical CCD camera system attached to the 2.1-m Otto-Struve Telescope (OST) at McDonald Observatory, USA. The new auto-guiding system differs from the original one in the following: instead of the cassegrain focus of the OST, it is attached to the finder scope; it has its own filter system for observation of bright targets; and it is controlled with the CQUEAN Auto-guiding Package, a newly developed auto-guiding program. Finder scope commands a very wide field of view at the expense of poorer light gathering power than that of the OST. Based on the star count data and the limiting magnitude of the system, we estimate there are more than 5.9 observable stars with a single FOV using the new auto-guiding CCD camera. An adapter is made to attach the system to the finder scope. The new auto-guiding system successfully guided the OST to obtain science data with CQUEAN during the test run in 2014 February. The FWHM and ellipticity distributions of stellar profiles on CQUEAN, images guided with the new auto-guiding system, indicate similar guiding capabilities with the original auto-guiding system but with slightly poorer guiding performance at longer exposures, as indicated by the position angle distribution. We conclude that the new auto-guiding system has overall similar guiding performance to the original system. The new auto-guiding system will be used for the second generation CQUEAN, but it can be used for other cassegrain instruments of the OST.

• 천문학회지
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• 제46권3호
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• pp.103-123
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• 2013

Star clusters are superb astrophysical laboratories containing cospatial and coeval samples of stars with similar chemical composition. We initiate the Sejong Open cluster Survey (SOS) - a project dedicated to providing homogeneous photometry of a large number of open clusters in the SAAO Johnson-Cousins' UBV I system. To achieve our main goal, we pay much attention to the observation of standard stars in order to reproduce the SAAO standard system. Many of our targets are relatively small sparse clusters that escaped previous observations. As clusters are considered building blocks of the Galactic disk, their physical properties such as the initial mass function, the pattern of mass segregation, etc. give valuable information on the formation and evolution of the Galactic disk. The spatial distribution of young open clusters will be used to revise the local spiral arm structure of the Galaxy. In addition, the homogeneous data can also be used to test stellar evolutionary theory, especially concerning rare massive stars. In this paper we present the target selection criteria, the observational strategy for accurate photometry, and the adopted calibrations for data analysis such as color-color relations, zero-age main sequence relations, Sp - MV relations, Sp - $T_{eff}$ relations, Sp - color relations, and $T_{eff}$ - BC relations. Finally we provide some data analysis such as the determination of the reddening law, the membership selection criteria, and distance determination.

• 전기전자학회논문지
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• 제22권3호
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• pp.658-663
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• 2018

본 논문에서는 실내 위치 추정시스템에 주로 사용되는 시퀀스 기반 위치추정(Sequence-Based Localization, SBL) 알고리즘의 성능향상을 위한 노드배치 알고리즘에 대해 연구한다. 기존의 노드선택 또는 배치알고리즘은 다수의 타겟이 위치하는 공간의 중심값에 노드들을 위치시켜 성능향상을 이루는 반면, SBL에서는 위치추적 알고리즘 특성상 타겟을 에워싸는 공간에서의 노드배치가 효율적일 수 있음에 주목한다. 이를 실현하기 위해 K-means clustering 알고리즘을 통한 노드배치 가능 공간을 선정하고, 그 선정된 공간상의 효율적 노드위치를 찾기 위해 2분법을 활용하여, 설계 복잡도가 낮은 노드배치 알고리즘을 제시한다. 제안된 노드배치알고리즘은 다양한 모의실험을 통해 무작위 노드배치 알고리즘 대비 뛰어난 위치추정성능을 보여주며, 노드위치를 위한 전역탐색 (full search)과 비교하여, 상당히 낮은 설계복잡도를 유지하면서도 만족할 만한 성능을 보인다.