• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.57.3-58
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• 2017

Single Point Diamond Turning (SPDT) is a cost-effective technique to fabricate metallic mirrors. In particular, the servo-assisted diamond turning option is highly useful for the fabrication of freeform surfaces. However, the SPDT process leaves periodic tool marks on machined mirror surfaces, leading to undesirable diffraction effect, as well as the deviation of input beam. In order to solve this problem, we propose new SPDT machining conditions to minimize tool marks. We will also show the results from optical measurement and Power Spectral Density (PSD) analysis to evaluate the expectable performance for applications in wide field infrared telescopes.

• Bulletin of the Korean Space Science Society
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• 2009.04a
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• pp.64.3-64.3
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• 2009

• Investigative Magnetic Resonance Imaging
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• v.22 no.4
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• pp.229-239
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• 2018

Purpose: To assess the diagnostic performance in detecting rotator cuff tears at 3T of non-arthrographic shoulder magnetic resonance imaging (MRI) using 3D isotropic turbo spin-echo (TSE-SPACE) sequence as compared with 2D sequences. Materials and Methods: Seventy-four patients who were arthroscopically confirmed to have underwent non-arthrographic shoulder MRI with 2D sequences and TSE-SPACE were included. Three independent readers retrospectively scored supraspinatus and infraspinatus tendon (SST-IST) and subscapularis tendon (SCT) tears on 2D sequences and TSE-SPACE. Results: The mean sensitivity, specificity, and accuracy of the three readers were 95%, 100%, and 95% on TSE-SPACE and 99%, 93%, and 98% on 2D sequences for detecting SST-IST tears, respectively, whereas those were 87%, 49%, and 68% on TSESPACE and 88%, 66%, and 77% on 2D sequences for detecting SCT tears, respectively. There was no statistical difference between the two sequences, except for in the specificity of one reader for detecting SCT tears. The mean AUCs of the three readers on TSE-SPACE and 2D sequences were 0.96 and 0.98 for detecting SST-IST tears, respectively, which were not significantly different, while those were 0.71 and 0.82 for detecting SCT tears, respectively, which were significantly different (P < 0.05). Conclusion: TSE-SPACE may have accuracy and reliability comparable to conventional 2D sequences for SST-IST tears at non-arthrographic 3T shoulder MRI, whereas TSE-SPACE was less reliable than conventional 2D sequences for detecting SCT tears.

• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.136-140
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• 2006

In this paper, we consider the detection of orthogonal space-time block codes (OSTBCs) without channel state information (CSI) at the receiver. Based on the conventional blind cyclic decoder, we propose an enhanced blind cyclic decoder which has higher system performance than the conventional one. Furthermore, the proposed decoder offers low complexity since it does not require the computation of singular value decomposition.

• Bulletin of the Korean Mathematical Society
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• v.50 no.3
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• pp.787-799
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• 2013

In this paper, we compute the sectional curvatures and the scalar curvature of the Siegel-Jacobi space $\mathb{H}_1{\times}\mathb{C}$ of degree 1 and index 1 explicitly.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.54.2-54.2
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• 2018

It is important to understand very fast CMEs which are the main cause of geomagnetic storms and solar particle events (SPEs). During this solar cycle 24, there are 10 very fast CMEs whose speeds are over 2000 km/s. Among these, there were only two fronside events (2012 January 23 and 2012 March 7) and they are associated with two major flares (M8.7 and X5.4) and the most strong SPEs (6310 pfu and 6530 pfu). They have a similar characteristics: there were successive CMEs within 2 hours in the same active region. We analyze their magnetic properties using SDO HMI magnetograms and kinematic ones from STEREO EUVI/COR1/COR2 observations. We can measure their speeds and initial accelerations without projection effects because their source locations are almost the limb. Additionally, we are investigating magnetic and kinematic characteristics of 8 backside events using AI-generated magnetograms constructed by deep learning methods.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.74.1-74.1
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• 2016

미국 텍사스 주 맥도날드 천문대에 위치한 2.1m 망원경에 부착된 SQUEAN (SED Camera for QUasars in EArly uNiverse)은 2010년부터 운용되고 있는 CQUEAN을 바탕으로 개발된 적외선 영역 광학기기이다. 20개의 필터 장착이 가능한 필터 휠 제어 시스템을 가지고 있는 SQUEAN 시스템은 SMOP (SQUEAN Main Observation software package), KFC82 (KHU Filter wheel Control software package for McDonald 82 inch Telescope), KAP82 (KHU Auto-guiding software Package for McDonald 82 inch Telescope) 등으로 구성되어 있다. 그러나 대형 필터 휠을 제어하는 모터의 토크부족과 감속기의 백래시(Backlash)의 영향으로 오프셋의 오차가 커서 초기위치의 재설정 없이 하룻밤 이상 관측을 지속하는데 어려움이 있었다. 토크가 크고 인코더가 장착된 모터 교체와 제어 프로그램 등을 변경하고, 백래시의 영향을 최소화할 수 있도록 소프트웨어로 보정하였다. 또한, SMOP로부터 네트워크 통신을 통해 초기화용 필터 마스크(Initial Filter Mask:IFM)를 제작하여 돔 플랫 이미지에서 정확한 필터의 위치를 측정하는 기능을 도입하였다. 이 발표에서는, 개선된 하드웨어 및 소프트웨어의 내용과 테스트한 결과에 대해 보여준다.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.1
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• pp.62-67
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• 2010

The spreading pathways which is the cause of infection on head and neck area are submandibular space, masticatory space, parapharyngeal space, retropharyngeal space, carotid sheath and mediastinum, etc. If spread to parapharyngeal area involving airway, such infection can be life-threatening by airway obstruction, or can cause vascular injury followed by hemorrhage, nerve injuries. Also, if spread to superficially, necrotizing fasciitis and many complications may occur including gangrene of skin. The key to successful treatment of infection on head and neck area is recognition of spreading pathways, early diagnosis and following therapeutic management. Our department present two cases, one is infection progressed superficially to suprasternal space, another is spreading deep according to parapharyngeal space, subclavian space and carotid sheath followed by airway obstruction, and obtained significant results with surgical incision and drainage, administration of selected antibiotics, continuous post-operative treatment. We report these 2 cases with literatures review.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.141-144
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• 2012

A mobile Rayleigh Doppler wind LIDAR at an eye-safe wavelength of 355 nm incorporating double-edge technique with triple-channel Fabry-Perot etalon is developed for wind measurement from 5 to 40km. The structure of this LIDAR system is described. An intercomparsion experiment with rawinsonde is made, showing good agreement with expected measurement accuracy. A continuous observation of stratosphere wind field for several days with temporal resolution of 15 min and spatial resolution of 200 m from 5 to 40 km is presented, demonstrating the stability and robustness of the LIDAR. A stratospheric quasi-zero wind layer can be found at around 20 km with a direction change from east to west evident in the continuous observation.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.49.3-49.3
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• 2021

The 76 cm telescope in Kyung Hee Astronomical Observatory is participating in the small telescope network of the SomangNet project, which started in 2020. Since the installation of the telescope in 1992, the system configuration has been changed several times. The optical system of this telescope has a Ritchey-Chrétien configuration with 76 cm in diameter and the focal ratio is f/7. The mount is a single fork equatorial type and its control system is operated by TheSkyX software. We use a science camera with a 4k × 4k CCD and standard Johnson-Cousins UBVRI filters, which cover a field of view of 23.7 × 23.7 arcmin. We are also developing the Kyung Hee Automatic Observing Software for the 76 cm telescope (KAOS76) for efficient operations. In this work, we present the standard star calibration results, the current status of the system, and the expected science capabilities.