• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.42.2-42.2
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• 2015

High frequency peakers (HFPs) are promising candidates for young active galactic nuclei (AGNs). Their small physical scale (< 1 kpc) and radio spectrum peaked at high frequency (> 5 GHz) are suggestive that it has been only about $10^2-10^3$ years since a central massive black hole in their host galaxies was launched. Until recently however, long-term monitoring radio observations at frequencies which are high enough to cover the true peak of HFP candidates were rare. Therefore, previous HFP samples are often contaminated by blazars, which are highly variable, hence may show a similar radio spectrum as HFPs depending on the observational epoch. In this work, we challenge to identify genuine young AGNs by monitoring HFP candidates at high radio frequencies. We performed single-dish monitoring of 19 candidates in 18 epochs over 2.5 years at 22 and 43 GHz using the Korean VLBI Network (KVN). Also, using KaVA, a combined array of the KVN and the VERA in Japan, we carried out 22 GHz VLBI observations of two HFPs and one blazar selected from our sample in order to compare their parsec scale (milli-arcsecond scale) morphology. HFPs are expected to have double/triple features, so called compact symmetric objects, which are scaled-down versions of extended radio galaxies, while blazars typically show core-jet morphology. We discuss the properties of AGNs at their very early evolutionary stage based on the results of the KVN and KaVA observations.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.48.1-48.1
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• 2015

We investigate the role of small-scale and large-scale environments in triggering nuclear activity of the local galaxies using a volume-limited sample with $M_r$ < -19.5 and 0.02 < z < 0.0685 from the Sloan Digital Sky Survey Data Release 7. To fix the mass of the supermassive black hole in its host galaxy, we limit the central velocity dispersion of the sample galaxies. The active galactic nuclei (AGN) host sample is composed of Type II AGNs identified with flux ratios of narrow emission lines with S/N > 6. In this study, we find that the AGN fraction of late-type host galaxies are commonly larger than of early type galaxies. The AGN fraction of host galaxy with late-type nearest neighbor starts to increase as the host galaxy approaches the virial radius of the nearest neighbor (about a few hundred kpc scale). Our result may support the idea that the hydrodynamic interaction with the nearest neighbor plays an important role in triggering the nuclear activity of galaxy. The early-type galaxies in high density regions show decline of AGN activity compared to ones in lower density regions, whereas the direction of the environmental dependence of AGN activity for late-type galaxies is rather opposite. We also find that the environmental dependence of star formation rate is analogous to one of AGN activity except in the high density region.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.74.2-74.2
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• 2015

Strong outflows from active galactic nuclei (AGNs) may play a crucial role in galaxy evolution. Integral-field spectroscopy (IFS) is the most powerful tool to study the detailed kinematics of AGN outflows. We present the on-going optical 3D spectroscopic survey of ionized gas outflows. Type 2 AGN sample is uniquely selected from SDSS DR7 with a luminosity-limit (i.e., L[O III] > $10^{41.5}erg/s$) as well as strong kinematic signatures of ionized gas outflows ([O III] velocity shift > ~200 km/s or [O III] velocity dispersion (FWHM) > 1000 km/s), defining an extremely rare population (< ~0.5%). Thus, these AGNs with strong outflow signatures are one of the best suites for investigating AGN feedback. The IFS observations cover several kpc scales for the central region of the host galaxies, providing a detailed information of the kinematics and geometry of the gas outflows. In this contribution, we report the current status of the survey and the preliminary results on gas kinematics of 18 AGNs, based on the Magellan/IMACS-IFU and the VLT/VIMOS data.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.183-186
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• 2005

We present results of the VLBA observation toward the radio continuum and water maser emissions in a nearby LINER galaxy NGC 1052. The jet structure observed in 2000 is similar to that in 1998, and the two jet structures in 1998 and 2000 support the sub-luminal motion with apparent velocity of 0.26c. Distribution of water maser spots are located ${\~}$0.05 pc shifted to southwest from the component which is supported to be the nucleus, and no rapid positional change of the water maser gas with respect to the central engine is seen from 1995 to 2000. The maser gas is positionally coincident with a plasma torus, and the position of the maser gas relative to the nucleus is stable from 1995 to 2000. The maser gas in NGC 1052 could be explained to be associated with the nuclear circumnuclear torus or disk like the situation found in the nucleus of NGC 4258.

• The Korean Journal of Cytopathology
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• v.7 no.2
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• pp.207-212
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• 1996

Angiosarcoma of the bone is rare with an incidence of 0.13%. It may be solitary or multiple. Its cytologic findings by FNA have rarely been reported. We report a case of angiosarcoma of the rib in a 66 year-old man. FNA revealed single or clusters of round to oval shaped cells in a hemorrhagic and myxoid background. The large central nuclei had irregular nuclear membrane, chromatin clumping and prominent nucleoli. The cytoplasm was scanty with an eosinophilic distinct cytoplasmic border. Erythrophagocytosis by malignant cells was also found. Histopathologic examination confirmed the diagnosis of angiosarcoma revealing irregular and complex anastomosing vascular channels lined by malignant round tumor cells, protruding into the lumen. Immunohistochemical staining revealed diffuse strong positive reaction to factor VIII-related antigen and CD31.

• The Korean Journal of Cytopathology
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• v.8 no.1
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• pp.83-86
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• 1997

Signet ring cell carcinoma is a variant of adenocarcinoma and has been rarely reported in the lung as a primary site. Recently, we experienced two cases of primary signet ring cell carcinoma in the lung without any other extrapulmonary lesion. Sputum cytology was performed and the tumor cells which have eccentrically located nuclei and abundnat mucinous cytoplasm were dispersed in diffuse sheets. On resected specimen, the signet ring cells occupied about $50{\sim}80%$ of all tumor cell nests. Histochemical staining revealed that the mucin produced by tumor cells was mostly carboxylated acid mucins. Ultrastructurally, the tumor cells contained variable sized membrane-bound mucin granules with weak central osmilophilic density and showed numerous surface microvilli, which represented that tumor cells arose from bronchial epithelial cells. In general, this tumor has diffusely infiltrative nature and the prognosis is fatal due to widespread metastasis before clinical discovery.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.169-173
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• 2017

We provide a new physical insight on the hot molecular clouds near the nucleus of the obscured AGNs. We performed near-infrared spectroscopic observations of heavily obscured AGNs in order to reveal physical characteristics of molecular clouds, especially focused on the CO fundamental ro-vibrational absorption around $4.7{\mu}m$. We have made systematic moderate-resolution spectroscopic observations toward 30 representative (U)LIRGs using the AKARI/IRC, and some of the ULIRGs showed the strong CO absorption feature. For three bright (U)LIRGs that show a steep red continuum with the deep CO absorption feature, IRAS 08572+3915, UGC 05101, and IRAS 01250+2832, we have also made high-resolution spectroscopic observations using the Subaru/IRCS. We have successfully detected many absorption lines up to highly excited rotational levels, and these lines are very deep and extremely broad. The derived physical conditions of molecular clouds are extreme; the gas temperature is as high as several 100 to a 1000 K, the $H_2$ column density is larger than $10^{22}cm^{-2}$, and the gas density is greater than $10^7cm^{-3}$. Such hot and dense molecular clouds must exist around the central engine of the AGN.

• The Korean Journal of Cytopathology
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• v.9 no.2
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• pp.187-191
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• 1998

Alveolar soft part sarcoma(ASPS) is a rare malignant neoplasm with a distinct clinicopathologic entity of which fine needle aspiration(FNA) cytologic findings have been described in only a few reports. Although patients usually present with an isolated soft-tissue mass in the extremity, metastasis can occur in about 13 % of total cases and the most frequent metastatic site is the lung. We have recently experienced a FNA cytologic case of ASPS in the lung. A 23-year-old female patient was admitted to this hospital due to 2-month-history of cough She had been good in health before the visit. Chest computed tomography revealed multiple, variable sized, bilateral pulmonary nodules. Physical examination and other staging work up revealed no other lesions except for pulmonary nodules. A percutaneous transthoracic FNA was performed from the pulmonary nodules. The smear was cellular and most cells were arranged singly. In addition, a few clusters lined by thin-walled vasculature with a pseudoalveolar pattern were present. Some of the tumor cells were large and polygonal lo oval with abundant granular or vacuolated cytoplasm. Most cells were naked nuclei showing finely granular chromatin pattern with prominent central nucleoli.

• The Korean Journal of Cytopathology
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• v.8 no.2
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• pp.143-149
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• 1997

Salivary duct carcinoma is rare high grade adenocarcinoma, arising from larger excretory duct in major salivary gland, resembling the ductal carcinoma of the breast histologically. We report a case of salivary duct carcinoma of left parotid gland in which fine needle aspiration cytology was performed. Cytologic examination revealed 1) moderate cellularity, 2) flat sheets or three dimensional, tightly cohesive clusters on the necrotic background, 3) sometimes cribriform or papillary configuration, 4) polygonal or cuboidal cells with moderate anisonucleosis with abundant, granular and eosinophilic cytoplasm, 5) round to oval nuclei with irregular chromatin clumps, and 6) 1 or 2 inconspicuous nucleoli. Histologically, the tumor is mainly composed of cribriform intraductal component with central comedonecrosis, and small foci of infiltrating component including well differentiated ductal structures or irregular sheets in a desmoplastic stroma.

• The Korean Journal of Cytopathology
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• v.7 no.1
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• pp.38-43
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• 1996

Epstein-Barr virus(EBV) is associated with a wide spectrum of benign and malignant disorders including leukoplakia, Hodgkln's lymphoma, central nervous system lymphoma, peripheral T cell lymphoma and nasopharyngeal undifferentiated carcinoma. There are several distinctive aspects of biology of the virus that are important in investigation of virus in clinical specimens. The abundant expression of the EBER mRNA transcripts makes possible the sensitive detection of latent expression in EBV-associated tumors. Although there has been a dramatic increased interest in the direct characterization of EBV in clinical specimens, there have been few studios about the effective and reliable positive controls in performing in situ hybridization technique for EBV, especially on paraffin-em bedded tissue. We applied Burkitts lymphoma ceil line as positive control in EBV in situ hydridization using Oncor Kit. The cell block of Burkitt lymphoma cell line(CCL85 EB-3) showed strong and specific positivity for EBER in situ in nuclei of EBV infected cells.