• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.529-535
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• 2011

The HF communication method is capable of communicating short and long distances without a separate relaying method and is used as the primary/secondary communication method in other nations. However, the Korean military strongly discouraged the use of the method due to issues regarding the skip zone and the fact that the usable frequency changes according to irregularities in the ionosphere. The NVIS communication is less susceptible to noise than typical communications using ionosphere reflection, and is also able to communicate short distances containing skip zones. In this paper, we inspect the NVIS communication methods of foreign nations in order to facilitate the use of HF communications, as well as provide solutions to the issues mentioned above. This paper explains the concept of NVIS communication, and investigates how the Korean military is implementing HF communications based on actual communications data of military corps. Based on this result, we have verified the possibility of overcoming skip zones through NVIS communications, and have considered the applicability of a prediction program in order to enhance the efficiency of HF communications.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.1-5
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• 2020

By adapting black body leadflame and thin film type Green A filter, we successfully demonstrated night vision imaging system (NVIS) Green A compatible LED. Fabricated NVIS compatible LEDs show small form factor compared to that of commercialized NVIS compatible LED. Especially, NVIS radiance and chromaticity of MIL-STD-3009 specification can be satisfied simultaneously and easily by controlling the color temperature of the white LED as well as the concentration of the Green A dye and the thickness of the Green A filter. The optimal dye concentration of the NVIS Green A filter is expected to be about 1 wt%. The results of this study are expected to contribute to miniaturization, weight reduction and localization of avionic display and lighting devices.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.62-67
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• 2021

In this study, we have successfully developed an unique NVIS Green A compatible LED by combining two technologies. One is white LED made with a black EMC (epoxy molding compound) lead frame. The other is NVIS Green A filter that shields the near infrared region made in the film method. The form factor of the developed NVIS Green A compatible LED was 2.0 × 2.0 × 0.95 mm. And it is possible to satisfy NVIS radiance and color limit specified in MIL-STD-3009 by controlling the concentration of Green A dye and the thickness of the NVIS filter as well as adjusting of color temperature of the white LED. From these results, we are expected that the developed NVIS Green A suitable LED is a promising solution for the weight reduction and the cost reduction of avionic applications.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.51-61
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• 2007

This paper concerns about the requirement analysis for night vision imaging system(NVIS), whose purpose is to intensify the available nighttime near infrared(IR) radiation sufficiently to be caught by the human eyes on a miniature green phosphor screen. The requirements for NVIS are NVIS radiance(NR), chromaticity, daylight legibility/readability, etc. The NR is a quantitative measure of night vision goggle (NVG) compatibility of a light source as viewed through goggles. The chromaticity is the quality of a color as determined by its purity and dominant wavelength. The daylight legibility/readability is the degree at which words are readable based on appearance and a measure of an instrument's ability to display incremental changes in its output value. In this paper, the requirements of NR, chromaticity, and daylight legibility/readability for Type I and Class B/C NVIS are analyzed. Also the rationale is shown with respect to those requirements.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.107-116
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• 2006

This paper deals with a development of night vision imaging system(NVIS) for the KO-1 aircraft. In the modern combat, NVIS has a tendency to be applied for night peculiar mission and pilot mission maximization. KO-1 aircraft, which was the first domestic applied NVIS, is forward air control acquired information of day/night enemy(foe) site and moving of enemy for low altitude flight. We have successfully finished a developmental requirement/criterion, development of system, and construction of test and evaluation through development of NVIS for the KO-1 aircraft. KO-1 aircraft is acquired timely initial operational capability.

• The Journal of Aerospace Industry
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• s.67
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• pp.71-94
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• 2004

전 세계 항공 산업의 비약적인 발전과 더불어 최근에는 군사용 및 항공수송을 위해 주간뿐만 아니라 야간에도 많은 비행이 요구되고 있으며, 이에 따라 항공기 안전운행의 필요성이 크게 대두되고 있다. 이러한 항공기의 안전운행에는 다양한 기술적인 발전이 진행되어 왔고, 야간시각시스템(NVIS)의 발전 역시 항공기 조종사에게 주간과 유사한 시각적 영상정보를 제공함으로써 심리적인 불안감을 해소시키고, 운항정보에 대한 신뢰성과 적시성을 증대시키며, 야간에 항공기를 안전하게 운항하기 위해 조종사의 업무부아(work load)를 줄이기 위한 노력으로 큰 관심사가 되어왔다. 또한 이러한 NVIS를 활용한 기술은 현재 군용항공기 뿐만이 아니라. 민간용 항공기, 자동차, 카메라, 레저용 등으로 그 범위가 확대되어 보급되고 있으며, 활용도 또한 커지고 있고, 수년 전부터 국내에도 이러한 기술이 적용되어 왔기에 이러한 항공기용 야간시각시스템(NVIS)에 대한 전반적인 내용을 소개하고, 향후 국내에서 개발/적용되는 항공기의 NVIS 기술에 대한 기본적인 평가방향을 제시하고자 한다.

• Korean Journal of Remote Sensing
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• v.39 no.6_3
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• pp.1779-1790
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• 2023

Satellite-based fog detection algorithms are being developed to detect fog in real-time over a wide area, with a focus on the Korean Peninsula (KorPen). The GEO-KOMPSAT-2A/Advanced Meteorological Imager (GK2A/AMI, GK2A) satellite offers an excellent temporal resolution (10 min) and a spatial resolution (500 m), while GEO-KOMPSAT-2B/Geostationary Ocean Color Imager-II (GK2B/GOCI-II, GK2B) provides an excellent spatial resolution (250 m) but poor temporal resolution (1 h) with only visible channels. To enhance the fog detection level (10 min, 250 m), we developed a fused GK2AB fog detection algorithm (FDA) of GK2A and GK2B. The GK2AB FDA comprises three main steps. First, the Korea Meteorological Satellite Center's GK2A daytime fog detection algorithm is utilized to detect fog, considering various optical and physical characteristics. In the second step, GK2B data is extrapolated to 10-min intervals by matching GK2A pixels based on the closest time and location when GK2B observes the KorPen. For reflectance, GK2B normalized visible (NVIS) is corrected using GK2A NVIS of the same time, considering the difference in wavelength range and observation geometry. GK2B NVIS is extrapolated at 10-min intervals using the 10-min changes in GK2A NVIS. In the final step, the extrapolated GK2B NVIS, solar zenith angle, and outputs of GK2A FDA are utilized as input data for machine learning (decision tree) to develop the GK2AB FDA, which detects fog at a resolution of 250 m and a 10-min interval based on geographical locations. Six and four cases were used for the training and validation of GK2AB FDA, respectively. Quantitative verification of GK2AB FDA utilized ground observation data on visibility, wind speed, and relative humidity. Compared to GK2A FDA, GK2AB FDA exhibited a fourfold increase in spatial resolution, resulting in more detailed discrimination between fog and non-fog pixels. In general, irrespective of the validation method, the probability of detection (POD) and the Hanssen-Kuiper Skill score (KSS) are high or similar, indicating that it better detects previously undetected fog pixels. However, GK2AB FDA, compared to GK2A FDA, tends to over-detect fog with a higher false alarm ratio and bias.

• Defense and Technology
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• no.4 s.278
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• pp.66-75
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• 2002

항공기의 야간임무 수행 능력을 최대화하고 조종사에게 심리적 안정감을 주어 전투력 향상을 극대화 할 수 있는 야시조명에 관한 지상시험평가 방법에 대하여 서술하였다. 야시조명 지상시험 평가는 설계된대로 야시조명원들이 정상 작동하는지를 평가하는 기능시험과 야간투시경의 원활한 작동을 위한 조명원들의 간섭현상을 평가하는 호환성시험으로 나눌 수 있다.

• Structural Engineering and Mechanics
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• v.51 no.4
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• pp.643-650
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• 2014

A chaotic vibration isolation system is designed according to the chaotic vibration theory in this paper. The strong nonlinearity is generated by the system. Line spectra in the radiated noise maybe easily detected caused by marine vessels. It is Important to reduce the line spectra by improving the acoustic stealth of marine vessels. A multi-degree-freedom (MDF) nonlinear vibration isolation system (NVIS) system is setup by the experiment and finite element method. The model is established with finite element method. The results show that the behavior of the device gradually varies from period bifurcation into chaotic state and the line spectrum is changed from single spectral structure into broadband spectral structure. It is concluded that chaotic vibration isolation is preferable contrasted on line spectra isolation.