• Journal of the Optical Society of Korea
• /
• v.8 no.4
• /
• pp.149-155
• /
• 2004

Newly developed modal transmission-line theory(MTLT) is used to analyze rigorously the optical power distribution in grating-assisted directional couplers(GADCs) with three guiding channels. By defining a novel coupling efficiency ${\eta}$ amenable to the rigorous analytical solutions of modal transmission-line theory, we explicitly evaluate the power coupling and distribution of TM modes. The results reveal that the incident power is sensitively partitioned through three output channels in terms of such grating parameters as the grating period, the duty cycle, and the operating wavelength.

• The Bulletin of The Korean Astronomical Society
• /
• v.39 no.2
• /
• pp.92.1-92.1
• /
• 2014

In astronomical spectroscopy, stable auto-guiding and accurate target centering capabilities are critical to increase the achievement of high observation efficiency and sensitivity. We developed an instrument control software for the Immersion GRating INfrared Spectrograph (IGRINS), a high spectral resolution near-infrared slit spectrograph with (R=40,000). IGRINS is currently installed on the McDonald 2.7 m telescope in Texas, USA. We had successful commissioning observations in March, May, and July of 2014. The role of the IGRINS slit-viewing camera (SVC) is to move the target onto the slit, and to provide feedback about the tracking offsets for the auto-guiding. For a point source, we guide the telescope with the target on the slit. While for an extended source, we use another a guide star in the field offset from the slit. Since the slit blocks the center of the point spread function, it is challenging to fit the Gaussian function to guide and center the target on slit. We developed several center finding algorithms, e.g., 2D-Gaussian Fitting, 1D-Gaussian Fitting, and Center Balancing methods. In this presentation, we show the results of auto-guiding performances with these algorithms.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.48 no.4
• /
• pp.142-152
• /
• 2011

In general, existing emergency evacuation guiding systems depend on visual techniques like emergency lights or LEDs. Actually people in the case of fire emergency condition may not obtain a range of view because of smoke from the fire. This paper introduces a technique to design an emergency guiding system using directivity sound to cope with this problem. In this case all speakers are serially connected for audio signal transmission in a serial fashion to achieve convenient speaker installation. Floyd algorithm is used to find shortest evacuation paths. Because serially connected multi-channel speakers are weak in case of disconnection, this paper uses a technique to solve the diagnostic problem. In the proposed system, a PC based on the USB protocol is used for control and observation. The system has achievements, such as increasing evacuation rate under emergency conditions, and serial transmission of audio signal for easy maintenance and low installation cost.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.38.1-38.1
• /
• 2010

McDonald 2.1m Otto Struve Telescope is located in the Davis Mountains, 450 miles west of Austin, Texas. The telescope was built in 1938, but it is still in demand today. CQUEAN (Camera for QUasar in Early uNiverse) will be attached on this telescope and perform Y-band imaging observations. Dynamics study of the telescope shows that tracking errors are 0.1 arcsec/100sec in declination direction and 0.4 arcsec/100sec in R.A. direction. In order to allow a long exposure (> a few minutes) of a target field, we are making auto-guiding system for the 2.1m telescope. The auto-guiding system of CQUEAN will be connected with TCS of the telescope. The expected number of stars on the CCD field (2.97 square arcminutes) is about 1.2 stars which are brighter than magnitude 17.5 in 2.97 square arcminutes. For more effective observation, we plan to implement moving mechanism in guiding system so that guide CCD camera can see wider off-axis fields.

• Publications of The Korean Astronomical Society
• /
• v.27 no.5
• /
• pp.391-397
• /
• 2012

The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation infrared space telescope optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. It will achieve the high resolution as well as the unprecedented sensitivity from mid to far-infrared range. The FPC (Focal Plane Camera) proposed by KASI as an international collaboration is a near-infrared instrument. The FPC-S and FPC-G are responsible for the scientific observation in the near-infrared and the fine guiding, respectively. The FPC-G will significantly reduce pointing error down to below 0.075 arcsec through the observation of guiding stars in the focal plane. We analyzed the pointing requirement from the focal plane instruments as well as the error factors affecting the pointing stability. We also obtained the expected performance in operation modes. We concluded that the FPC-G can achieve the pointing stability below 0.075 arcsec which is the requirement from the focal plane instruments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.6
• /
• pp.914-919
• /
• 2000

A simple orthogonal mode transducer(OMT) for X-band has been proposed in this paper. This OMT is designed such that a polarized wave can be guided in a direction using several thin guiding posts, and the other orthogonally polarized wave can be guided in the other direction using other thin guiding posts. The OMT consists of a T-shaped waveguide section with guiding posts, two tapering waveguide arms, and has three flanges for connection with two adapters and an antenna. The optimum numbers and the optimum positions of the guiding posts were obtained numerically using the HFSS CAD tool. The isolation between two polarizations in a manufactured OMT is higher than 42.8 dB and the reflection from the OMT is lower than -17.5 dB at the frequency band of 9.5 GHz

• Korean Journal of Digital Imaging in Medicine
• /
• v.10 no.1
• /
• pp.21-28
• /
• 2008

Diagnostic display monitor QA according to AAPM TG18 is usually performed by PACS administrator, product manager and reading doctor, and for acceptance testing and periodic quality control evaluation, a combination of visual and quantitative tests can be used, as outlined in sections 5 and 6 of 'assessment of display performance for medical imaging systems'. Although many display tests can be performed visually, a more objective and quantitative evaluation of display performance requires special test tools. The required instruments vary in their complexity and cost, depending on the context of the evaluation(research, acceptance testing, or quality control) and how thorough the evaluation needs to be. Objective and reliable assessment of many display characteristics can be performed with relatively inexpensive equipment, So, we made 'AAPM TG18 guiding instrument' to ues variable purpose of the evaluation of 'geometrical distortions(quantitative"', 'veiling glare(visual)' and 'sensor calibration'. The spatial measurements for the quantitative evaluation of geometric distortions, and the measurement of the veling-glare ring response function which provides information regarding the spatial extent of the luminance spread, can be performed using the TG18 guiding instrument can be used to sensor calibration to standardize the basic rate of 0% luminance when periodic calibration.

• Korean Journal of Heritage: History & Science
• /
• v.57 no.3
• /
• pp.162-182
• /
• 2024

Since the adoption of the World Heritage Convention, sites associated with dark histories have been inscribed as World Heritage sites over the past fifty years. However, in 2018, the review of nomination dossiers for these sites was temporarily suspended to prevent additional discomfort or the conflicts these inscriptions might cause. Despite concerns raised by experts about nominations of these sites, the increasing demands from State Parties led to the adoption of the Guiding Principles for the Preparation of Nominations Concerning Sites of Memory Associated with Recent Conflicts. These Guiding Principles have made it possible to inscribe such sites as World Heritage sites. The Guiding Principles play a crucial role in outlining the nature and criteria for inscription, the components required in the nomination dossier, and mechanisms for notifying a contestation in cases of differing interpretations of the site. Their primary aim is to minimize further conflicts that may arise from the inscription of sites of memory. They affirm that such sites can contribute to achieving the objectives of the World Heritage Convention and represent a significant step in addressing heritage interpretation in the World Heritage system. The amendment of the Operational Guidelines to incorporate a contestation mechanism has arguably established a more transparent and open inscription process. However, the Guiding Principles also have limitations. Among the ten criteria set by the World Heritage Convention, sites related to conflicts or dark histories can use Criterion (vi). This criterion focuses on the site's outstanding universal value linked to historical events or associations, regardless of physical evidence. If a State Party chooses not to use Criterion (vi), the application of the Guiding Principles cannot be expected. Furthermore, while the Guiding Principles require a heritage interpretation strategy in the nomination dossier, the lack of detailed guidance may confuse nominating countries. Sites of memory associated with recent conflicts are not just places that need protection and remembrance due to their association with dark histories. They have also evolved to become spaces for reconciliation and healing. The inscription of these sites as World Heritage sites is not just a recognition of their historical significance, but also a platform for discussing the impact of past conflicts on modern society. It opens up a dialogue on how current generations can address these issues. With the adoption of the Guiding Principles, we hope that inscribed sites will not only promote reconciliation and healing but also serve as a starting point for addressing present and future challenges.

• Korean Journal of Optics and Photonics
• /
• v.20 no.1
• /
• pp.57-60
• /
• 2009

We consider introducing an optical thin film to the light guiding wall of a pixel in order to enhance the light guiding efficiency of a CMOS image sensor. Simulating the reflectance as a function of the incidence angle using the Essential Macleod program, we find that the range of total internal reflection is greatly increased for several materials. Particularly when air is chosen as the thin film material, the critical angle of total internal reflection could be shifted to about 50 degrees.

• Agricultural and Biosystems Engineering
• /
• v.2 no.2
• /
• pp.69-74
• /
• 2001

Detection of operation lines in farm works, object recognition and obstacle avoidance are essential pre-requisite technologies for unmanned agricultural machinery. A CCD camera, which has been largely used for these functions, is expensive and has difficulty in real-time signal processing. In this study, a laser range sensor was selected as the guiding vision for unmanned agricultural machinery such as a tractor. To achieve this capability, algorithms for distance measurement, signal filtering, object recognition, and obstacle avoidance were developed. Computer simulations were carried out to evaluate performance of the algorithms. Experiments were also conducted with various materials and shapes, Laser beam lost its intensity for poor reflective materials, resulting in less range value than actual, so a compensation technique was considered to be necessary. Object detection system was fabricated on an agricultural tractor and the performance was evaluated. As test result for obstacle detection and avoidance in field, to detect and avoid obstacle for path finding with guiding system for unmanned agricultural machinery was enable.