• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.20-22
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• 2014

교차방위법은 해군 함정이 연안항해에서 주로 사용하는 함위 산출법이다. 항해 보조장비가 많이 개발되었음에도 불구하고 실물표를 대상으로 측정하는 실측위치이기 때문에 해군함정에서 현재까지 가장 폭넓게 활용되고 있다. 교차방위법의 정확도에 미치는 영향요소는 여러가지가 있지만, 본 논문에서는 함정의 기본속력이 미치는 영향을 연구하였다. 긴급한 작전상황의 경우 함정은 안전속력보다 빠른 속력으로 협수로를 통과해야 한다. 이러한 작전환경에서 속력의 증가가 얼마나 위치 정확도의 오차를 가져오는지 확인하여 함정을 운용하는 지휘관에게 참고자료를 제공하고자 한다.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.451-456
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• 2015

This research examines the use of Cross Bearing in the Republic of Korea Navy. Specifically, this study focuses on the degrees of errors caused by the order of measuring targets and suggests a new method to determine Advice Course. It then reviews the appropriateness of the contents of Location Report that is regularly to the duty officer during a voyage in a narrow channel. Whenever a naval vessel passes through a narrow channel, many number of sailors are assigned to diverse positions in order to enhance navigational safety. Even though it is possible to easily recognize the location of a ship with helps of various kinds of navigational equipments using state-of-the-art technology, there are still several situations where sailors' efforts are indispensible for calculating the position of their ship : when the ship is damaged during an engagement with enemies and when the enemies interfere (GPS) signals. In addition, the particularity of naval vessels in which many number of crew members can be assigned to various positions supports for the suitability of the use of Cross Bearing in the Navy. This study will contribute to navigational safety of the ROK Navy and fostering junior naval officers' seamanship.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.07a
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• pp.24-27
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• 2015

본 연구에서는 해군 함정이 협수로 연안항해시 함위를 산출하는 방법인 교차방위법을 다양한 관점에서 살펴보았다. 물표측정 순서에 따른 함위의 정확도를 조함권자가 보고를 받는 시점을 기준으로 살펴보았으며, 함위 산출 후 조함권자에게 보고사항 중 초급 장교들이 어려워하는 권고침로 산출방법을 알기쉽게 정리하였다. 또한 상황에 따라 함 항해안전 우선순위를 구분하여 간략하게 보고하는 방법을 제시함으로써 협수로 항해를 하는 해군함정의 안전항해를 보장하기 위한 방안을 제시하였다.

• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.150-158
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• 2008

The exact transmission coefficients at the interface between a uniaxial anisotropic medium and an isotropic medium at? oblique incidence are derived by applying the extended Jones matrix method. When the birefringence of the uniaxial anisotropic medium is small ($|n_e-n_o|\;{\ll}\;n_o,\;n_e$), the exact transmission coefficients are compared with those by the conventional extended Jones matrix method by Yeh et al. They showed an excellent agreement with each other. In addition, using the exact transmission coefficients, we calculated the polarization characteristics of a light through a uniaxial medium to an incident light with arbitrary polarization state at? oblique incidence. We compared the transmittances of an unpolarized light through a pair of crossed o-type polarizers by two different methods and calculated the transmittance as the variation of the optical constants of the polarizers to evaluate of the extinction ratio. The polarization analysis method using the exact transmission coefficients can be applied to polarization characteristics of a light through a uniaxial medium with large birefringence as well as to liquid crystals and to optical anisotropic material.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.3
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• pp.61-74
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• 2016

The purpose of this paper is to analyze the relationship between the location of the epicenter of a medium-sized earthquake(magnitude 4.8) that occurred on January 20, 2007 in the Odaesan area with lineament features using a shaded relief map(1/25,000 scale) and satellite images from LANDSAT-8 and KOMPSAT-2. Previous studies have analyzed lineament features in tectonic settings primarily by examining two-dimensional satellite images and shaded relief maps. These methods, however, limit the application of the visual interpretation of relief features long considered as the major component of lineament extraction. To overcome some existing limitations of two-dimensional images, this study examined three-dimensional images, produced from a Digital Elevation Model and drainage network map, for lineament extraction. This approach reduces mapping errors introduced by visual interpretation. In addition, spline interpolation was conducted to produce density maps of lineament frequency, intersection, and length required to estimate the density of lineament at the epicenter of the earthquake. An algorithm was developed to compute the Value of the Relative Density(VRD) representing the relative density of lineament from the map. The VRD is the lineament density of each map grid divided by the maximum density value from the map. As such, it is a quantified value that indicates the concentration level of the lineament density across the area impacted by the earthquake. Using this algorithm, the VRD calculated at the earthquake epicenter using the lineament's frequency, intersection, and length density maps ranged from approximately 0.60(min) to 0.90(max). However, because there were differences in mapped images such as those for solar altitude and azimuth, the mean of VRD was used rather than those categorized by the images. The results show that the average frequency of VRD was approximately 0.85, which was 21% higher than the intersection and length of VRD, demonstrating the close relationship that exists between lineament and the epicenter. Therefore, it is concluded that the density map analysis described in this study, based on lineament extraction, is valid and can be used as a primary data analysis tool for earthquake research in the future.