• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.234.1-234.1
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• 2012

The largest array SKA (Square Kilometre Array) project was proposed by astronomers from 10 countries, and first coordinated by the LTWG (Large Telescope Working Group) formed at the General Assembly of URSI (International Union of Radio Science) in 1993. It enters the pre-construction phase (2012-2015), towards the 10% SKA construction (2016-2019) called SKA1 and the rest of SKA (2019-2023) called SKA 2, under the leadership of the SKA Organisation (SKAO) established on November 23, 2011. I will review the Chinese participation in the SKA project at national, regional and global levels in the past two decades. During such a Long March to the SKA, a number of national Megascience projects have taken root and have been (are being) successfully constructed, with costs at the 100 M US dollar level, including the largest dish FAST (Five-hundred meter Aperture Spherical Telescope), which can be seen as a forerunner of the KARST (Kilometre Area Radio Synthesis Telescope) project, being as one of the two LDSN (Large Diameter Small Number) concepts for realizing the SKA. A close look at the FAST project gives an impressive snapshot of the construction phase in China.

• BMB Reports
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• v.52 no.2
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• pp.157-162
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• 2019

Our previous study found that two novel cancer-related genes, PRR11 and SKA2, constituted a classic gene pair that was regulated by p53 and NF-Y in lung cancer. However, their role and regulatory mechanism in breast cancer remain elusive. In this study, we found that the expression levels of PRR11 and SKA2 were upregulated and have a negative prognotic value in breast cancer. Loss-of-function experiments showed that RNAi-mediated knockdown of PRR11 and/or SKA2 inhibited proliferation, migration, and invasion of breast cancer cells. Mechanistic experiments revealed that knockdown of PRR11 and/or SKA2 caused dysregulation of several downstream genes, including CDK6, TPM3, and USP12, etc. Luciferase reporter assays demonstrated that wild type p53 significantly repressed the PRR11-SKA2 bidirectional promoter activity, but not NF-Y. Interestingly, NF-Y was only essential for and correlated with the expression of PRR11, but not SKA2. Consistently, adriamycin-induced (ADR) activation of endogenous p53 also caused significant repression of the PRR11 and SKA2 gene pair expression. Notably, breast cancer patients with lower expression levels of either PRR11 or SKA2, along with wild type p53, exhibited better disease-free survival compared to others with p53 mutations and/or higher expression levels of either PRR11 or SKA2. Collectively, our study indicates that the PRR11 and SKA2 transcription unit might be an oncogenic contributor and might serve as a novel diagnostic and therapeutic target in breast cancer.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.63-63
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• 2012

The Square Kilometre Array (SKA) will be the world's largest and most sensitive radio telescope. It will address a wide range of fundamental questions in physics, astrophysics, cosmology and astrobiology. Australia, one of the two countries selected to host the SKA, has spent several years preparing by opening up the Murchison Radio-astronomy Observatory (MRO) as a uniquely radio quiet site in Western Australia, and by constructing the world's most powerful radio survey telescope, the Australian SKA Pathfinder (ASKAP). The SKA will be built in two phases. Phase I will include ASKAP, which will use novel phased-array feeds and grow to become "SKA-survey". Phase I will also include a dish array ("SKA-mid") in South Africa and a low-frequency array ("SKA-low") in Australia, and is slated for operation from about 2020. Phase II of the SKA will consist of further expansion of SKA-low and SKA-mid and is due for completion in the middle of the next decade.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.74.2-74.2
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• 2011

SKA(Square Kilometre Array)는 수많은 전파망원경으로 이루어진 간섭계로, 그 총 유효 단면적이 약 1평방킬로미터이기 때문에, SKA라는 이름이 붙었다. 2024년 가동 예정인 SKA는, 감도(sensitivity)는 현존하는 가장 좋은 전파간섭계보다 50배, 하늘 서베이 속도는 약 만 배 빠를 것으로 예상된다. SKA는 파장 대역 별로 세 가지 서로 다른 전파 간섭계 (Sparse Aperture Array, Dense Aperture Array, and Dish Array)를 설치할 예정이다. 본 발표에서는 최근 SKA 개념 설계, SKA를 위한 조직 변화, 그리고 한국 참여 현황을 소개하겠다.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.234.2-234.2
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• 2012

As the accuracy in the measurement of cosmological parameters is ever-increasing in this era of precision cosmology, astrophysical constraints on high-redshift universe is also getting tighter. Three dimensional (3D) tomography of the high-redshift (z>~7) universe is expected to be made through the next-generation radio telescopes including various SKA pathfinders and SKA itself, which calls for extensive theoretical predictions. We present our new simulations of cosmic reionization covering the full dynamic range of radiation sources, and also the mock data for the (1) large-scale CMB polarization anisotropy for Planck mission, (2) small-scale, kinetic Sunyaev-Zel'dovich effect for South Pole Telescope project, and (3) 21-cm observations. We show that the new constraints on CMB from Planck will constrain the models of reionization significantly, which then should be tested by 3D tomography of high-redshift universe through the 21-cm observations by future radio telescopes.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.83.1-83.1
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• 2010

In the last meeting of KAS, we reported the first statistical study of Faraday rotation measure (RM) in the large-scale structure of the universe using the data of cosmological structure formation simulations. With a turbulence dynamo model for the intergalactic magnetic field (IGMF), we predicted that the root mean square of RM through filaments is \sim 1 rad/m^2. Future radio observatories such as the Square Kilometer Array (SKA) could detect this signal level. However, it is known that the typical foreground galactic RM is a few tens and less than ten rad/m^2 in the low and high galactic latitudes, respectively. So the RM in the large-scale structure could be detected only after the foreground galactic RM is removed. In this talk, we show how we remove the foreground galactic RM and what we obtain from the masked data, by using some noise models and masking techniques. Our results can be used to simulate future RM observations by SKA, and eventually to constrain the origin and evolution of the IGMF in the large-scale structure.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.32.2-32.2
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• 2014

We present a prediction for 21cm differential brightness temperature (dTb) from a set of strongly clustered sources of Population III and II objects at high redshift, from a suite of numerical simulations of their formation and radiative processes. These objects are located inside a highly biased density environment ("Rarepeak"), which is a rare, high-density peak which extends to ~7 comoving Mpcs. We study the impact on the resulting 21 cm signal from their ultraviolet and X-ray properties. The boost of emission (dTb>0) by high-density environment, moderate leakage of X-ray photons, and strong absorption due to Lyman-alpha pumping contrive to make Rarepeak a discernible, spatially-extended (sky angle~10') object around z~15, which is found to be detectable as a single object by Square Kilometre Array (SKA) with integration time of ~[600-2000] hours. We also examine detectability of many such peaks through SKA precursors.

• The Bulletin of The Korean Astronomical Society
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• v.34 no.1
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• pp.114.2-114.2
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• 2009

• Journal of Korean Neurosurgical Society
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• v.65 no.5
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• pp.719-729
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• 2022

Objective : The ossification of the ligamentum flavum (OLF) is one of the major causes of thoracic myelopathy. Surgical decompression with or without instrumented fusion is the mainstay of treatment. However, few studies have reported on the added effect of instrumented fusion. The objective of this study was to compare clinical and radiological outcomes between surgical decompression without instrumented fusion (D-group) and that with instrumented fusion (F-group). Methods : A retrospective review was performed on 28 patients (D-group, n=17; F-group, n=11) with thoracic myelopathy due to OLF. The clinical parameters compared included scores of the Japanese Orthopedic Association (JOA), the Visual analogue scale of the back and leg (VAS-B and VAS-L), and the Korean version of the Oswestry disability index (K-ODI). Radiological parameters included the sagittal vertical axis (SVA), the pelvic tilt (PT), the sacral slope (SS), the thoracic kyphosis angle (TKA), the segmental kyphosis angle (SKA) at the operated level, and the lumbar lordosis angle (LLA; a negative value implying lordosis). These parameters were measured preoperatively, 1 year postoperatively, and 2 years postoperatively, and were compared with a linear mixed model. Results : After surgery, all clinical parameters were significantly improved in both groups, while VAS-L was more improved in the F-group than in the D-group (-3.4±2.5 vs. -1.3±2.2, p=0.008). Radiological outcomes were significantly different in terms of changes in TKA, SKA, and LLA. Changes in TKA, SKA, and LLA were 2.3°±4.7°, -0.1°±1.4°, and -1.3°±5.6° in the F-group, which were significantly lower than 6.8°±6.1°, 3.0°±2.8°, and 2.2°±5.3° in the D-group, respectively (p=0.013, p<0.0001, and p=0.037). Symptomatic recurrence of OLF occurred in one patient of the D-group at postoperative 24 months. Conclusion : Clinical improvement was achieved after decompression surgery for OLF regardless of whether instrumented fusion was added. However, adding instrumented fusion resulted in better outcomes in terms of lessening the progression of local and regional kyphosis and improving leg pain. Decompression with instrumented fusion may be a better surgical option for thoracic OLF.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.133-140
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• 2005

In order to accelerate the rate of consolidation settlement and gain a required shear strength for a given soft clay deposit, vertical drain method combined with a preloading technique has been widely applied. In this paper, a theory of axisymmetric nonlinear consolidation fer drainage-installed deposit, which considers secondary compression (or creep) during primary consolidation, as well as the variations of compressibility and permeability during the consolidation process, has been developed. A computer program named AXICON based on Hypothesis B fur the analysis of axisymmetric nonlinear consolidation was developed by adopting finite difference method. The results of AS(ICON were compared with Hansbo's solution based on Hypothesis A, as well as in-situ settlements and pore pressures measured in test embankment of Ska-Edeby. The results indicated that Hypothesis A usually underestimated the in-situ settlement and Hypothesis B was considered to be logically correct. It was also shown that one may able to appropriately predict the real in-situ behaviors using the proposed program.