• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.39 no.6
• /
• pp.563-569
• /
• 2021

With the launch of Compact Advanced Satellite 500 series of various characteristics and the operation of KOMPSAT-3/3A, uses of high-resolution satellite images have been continuously increased. Especially, in order to provide satellite images in the form of ARD (Analysis Ready Data), various pre-processing such as geometric correction and radiometric correction have been developed. For pre-processing of high spatial satellite imagery, auxiliary information, such as solar zenith, solar azimuth and offnadir angle, should be required. However, most of the high-resolution satellite images provide the solar zenith and nadir angle for the entire image as a single variable. In this paper, the solar zenith and offnadir angle corresponding to each pixel of the image were calculated using RFM (Rational Function Model) and auxiliary information of the image, and the quality of extracted information were evaluated. In particular, for the utilization of pixel-based solar zenith and offnadir angle, pixel-based auxiliary data were applied in calculating the top of atmospheric reflectance, and comparative evaluation with a single constant-based top of atmospheric reflectance was performed. In the experiments using various satellite imagery, the pixel-based solar zenith and offnadir angle information showed a similar tendency to the auxiliary information of satellite sensor, and it was confirmed that the distortion was reduced in the calculated reflectance in the top of atmospheric reflectance.

• Composites Research
• /
• v.19 no.1
• /
• pp.9-14
• /
• 2006

Experimental investigation on heat transfer ratio was firstly performed with three types of sandwich panels such as the Carbon/Epoxy Skin-Aluminum Honeycomb and Balsa Core Sandwich Panel of 37mm thickness, the Carbon/Epoxy Aluminum Skin-Honeycomb Core Sandwich Panel of 57mm thickness (including insulator) and the Carbon/Epoxy Skin-Aluminum Honeycomb Core Sandwich Panel of 37mm thickness based on the KS F 2278:2003(Insulation test method of windows). In additional to this investigation, experimental tests were also done for evaluation of heat transportation ratio with the Aluminum Skin- Aluminium Honeycomb Sandwich Panels of 27mm and 35mm thickness, and Aluminum Skin-Foaming Aluminum Sandwich Panel of 27mm thickness by the KS F2277:2002 (Insulation measuring method of construction component-Calibration heat box method or protective heat box method). In this study, it was found that the larger net heat transfer cross sectional area between the skin and the sandwich core is given, the higher heat transportation ratio occurs. It was also found that the hybrid type insulation had better insulation characteristics compared to the non-hybrid type insulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.4
• /
• pp.287-295
• /
• 2022

As low altitude long-range artillery threat has been strengthened, the development of anti-artillery interception system to protect assets against its attacks will be kicked off. We view the defense of long-range artillery attacks as a typical dynamic weapon target assignment (DWTA) problem. DWTA is a sequential decision process in which decision making under future uncertain attacks affects the subsequent decision processes and its results. These are typical characteristics of Markov decision process (MDP) model. We formulate the problem as a MDP model to examine the assignment policy for the defender. The proximity of the capital of South Korea to North Korea border limits the computation time for its solution to a few second. Within the allowed time interval, it is impossible to compute the exact optimal solution. We apply approximate dynamic programming (ADP) approach to check if ADP approach solve the MDP model within processing time limit. We employ Shoot-Shoot-Look policy as a baseline strategy and compare it with ADP approach for three scenarios. Simulation results show that ADP approach provide better solution than the baseline strategy.

• Conservation Science in Museum
• /
• v.30
• /
• pp.101-126
• /
• 2023

Bogjeon chongtong, a military firearm from the Joseon Dynasty, remains undocumented with extant ones only discovered relatively recently. This study examined the structural and material characteristics of the bogjeon chongtong by comparing the specifications, shapes, inscriptions, and components of 12 pieces of bogjeon chongtong, which have not been described in detail to date. Bogjeon chongtong has certain set properties in terms of its specifications and shapes. This study also estimated the number of projectiles fired at once by comparing the specifications and records. In terms of design, the handle slot has an outline engraved in relief along with the name of the artifact. The inscribed outline is the most notable feature of the bogjeon chongtong that is not seen in other chongtong artifacts. Therefore, this study analyzed the inscription techniques used in the production process. The main ingredients of bogjeon chongtong are copper and tin, with a tin content of 6wt%. It was confirmed that this is highly similar to the average composition of bronze gunpowder weapons of the Joseon Dynasty as identified in prior research, and that it is also similar to the bronze gunmetal of medieval Europe. These conclusions were drawn in consideration of the material properties required for gunpowder weapons, which allows the inference that the materials used for firearms were selected by prioritizing functionality based on the alloy ratio.

• Korean Journal of Remote Sensing
• /
• v.30 no.4
• /
• pp.455-464
• /
• 2014

After launching the Geostationary Ocean Color Imager (GOCI) on June 2010, field campaigns were performed routinely around Korean peninsula to collect in-situ data for calibration and validation. Key measurements in the campaigns are radiometric ones with field radiometers such as Analytical Spectral Devices FieldSpec3 or TriOS RAMSES. The field radiometers must be regularly calibrated. We, in the paper, introduce the optical laboratory built in KOSC and the relative calibration method for in-situ measurement spectroradiometer. The laboratory is equipped with a 20-inch integrating sphere (USS-2000S, LabSphere) in 98% uniformity, a reference spectrometer (MCPD9800, Photal) covering wavelengths from 360 nm to 1100 nm with 1.6 nm spectral resolution, and an optical table ($3600{\times}1500{\times}800mm^3$) having a flatness of ${\pm}0.1mm$. Under constant temperature and humidity maintainance in the room, the reference spectrometer and the in-situ measurement instrument are checked with the same light source in the same distance. From the test of FieldSpec3, we figured out a slight difference among in-situ instruments in blue band range, and also confirmed the sensor spectral performance was changed about 4.41% during 1 year. These results show that the regular calibrations are needed to maintain the field measurement accuracy and thus GOCI data reliability.

• Progress in Medical Physics
• /
• v.16 no.4
• /
• pp.214-219
• /
• 2005

As part of Korean retinal prosthesis project, we have provided preliminary experimental results regarding voltage parameters for the stimulation of chemically degenerated rabbit retina. Since our APB-treated chemically degenerated retina is only ON-pathway blocked, now we switch our experiments to more appropriate retinal degeneration model, genetically degenerated retina model (RD mouse: rd/rd (C3H/HeJ)). Before studying with RD mouse, we started control experiments with normal SD rat to understand characteristics of retinal ganglion ceil activity with postnatal maturation in rodents. Ganglion cell activities were recorded with 8${\times}$8 multi-electrode array. Moving spontaneous bursts appeared until postnatal day of 15. During pre-eye opening period, no light evoked response appeared. After postnatal day of 2 weeks (post-eye opening period), ON-, OFF- and ON/OFF response appeared. The fractional distributions of ON, OFF, and ON/OFF ganglion cell is about $40\%,\;50\%$, and $5\%$. The percentage ($\%$) of light evoked response in each dorso-temporal, ventral, and dorso-nasal area of eye is about $50\%,\;37.5\%$ and $12.5\%$, respectively. We concluded that the optimal period for experiment in rodent is about postnatal day of 2${\~}$3 weeks.

• Korean Journal of Remote Sensing
• /
• v.38 no.2
• /
• pp.189-198
• /
• 2022

In this present study, we investigated the effect of the offset correction factor calculation method on the sulfur dioxide (SO₂) column density in the SO₂ retrieval algorithm of the Geostationary Environment Monitoring Spectrometer (GEMS) launched in February 2020. The GEMS operational SO₂ retrieval algorithm is the Differential Optical Absorption Spectroscopy (DOAS) - Principal Component Analysis (PCA) Hybrid algorithm. In the GEMS Hybrid algorithm, the offset correction process is essential to correct the absorption effect of ozone appearing in the SO₂ slant column density (SCD) obtained after spectral fitting using DOAS. Since the SO₂ column density may depend on the conditions for calculating the offset correction factor, it is necessary to apply an appropriate offset correction value. In this present study, the offset correction values were calculated for days with many cloud pixels and few cloud pixels, respectively. And a comparison of the SO₂ column density retrieved by applying each offset correction factor to the GEMS operational SO₂ retrieval algorithm was performed. When the offset correction value was calculated using radiance data of GEMS on a day with many cloud pixels was used, the standard deviation of the SO₂ column density around India and the Korean Peninsula, which are the edges of the GEMS observation area, was 1.27 DU, and 0.58 DU, respectively. And around Hong Kong, where there were many cloud pixels, the SO₂ standard deviation was 0.77 DU. On the other hand, when the offset correction value calculated using the GEMS data on the day with few cloud pixels was used, the standard deviation of the SO₂ column density slightly decreased around India (0.72 DU), Korean Peninsula (0.38 DU), and Hong Kong (0.44 DU). We found that the SO₂ retrieval was relatively stable compared to the SO₂ retrieval case using the offset correction value on the day with many cloud pixels. Accordingly, to minimize the uncertainty of the GEMS SO₂ retrieval algorithm and to obtain a stable retrieval, it is necessary to calculate the offset correction factor under appropriate conditions.

• Journal of Plant Biotechnology
• /
• v.38 no.4
• /
• pp.293-300
• /
• 2011

This study is conducted to develop an efficient transformation system via particle bombardment with PLBs (Protocorm-like bodies) in Cymbidium. For this, pCAMBIA3301 vector which carries a herbicide-resistant bar gene and gus gene as a reporter gene was used for transformation with Cymbidium cultivars 'Youngflower ${\times}$ masako' line. To select transformants, proper concentration of herbicide, PPT (phosphinotricin), should be determined. As a result, 5 mg/l of PPT was selected as a proper concentration. Further, proper conditions for particle bombardment were determined to obtain a high frequency of transformation. Results showed that 1.0 ${\mu}g$ of DNA concentration, 1,100 and 1,350 psi for helium gas pressure, 1.0 ${\mu}m$ of gold particle and 6 cm of target distance showed the best result for the particle bombardment experiment. Also, pre-treatment with combination 0.2 M sorbitol and 0.2 M mannitol for 4 hrs prior to genetic transformation increased the transformation efficiency up to 2.5 times. Using transformation system developed in this study, 3.2 ~ 4.0 transgenic cymbidium plants can be produced from 100 bombarded PLBs on average. Putative transgenic plants produced in this system confirmed the presence of the bar gene by PCR analysis. Also, leaves from randomely selected five transgenic lines were applied for Basta solution (0.5% v/v) to check the resistance to the PPT herbicide. As a result, three of them showed resistance and one of them showed the strongest resistance with the maintenance of green color as non-transformed plants showed. Using this established transformation system, more genes of interests can be introduced into Cymbidium plants by genetic transformation in the future.

• Korean Journal of Remote Sensing
• /
• v.36 no.5_2
• /
• pp.989-1006
• /
• 2020

Building change monitoring based on building detection is one of the most important fields in terms of monitoring artificial structures using high-resolution multi-temporal images such as CAS500-1 and 2, which are scheduled to be launched. However, not only the various shapes and sizes of buildings located on the surface of the Earth, but also the shadows or trees around them make it difficult to detect the buildings accurately. Also, a large number of misdetection are caused by relief displacement according to the azimuth and elevation angles of the platform. In this study, object-based building detection was performed using the azimuth angle of the Sun and the corresponding main direction of shadows to improve the results of building change detection. After that, the platform's azimuth and elevation angles were used to detect changed buildings. The object-based segmentation was performed on a high-resolution imagery, and then shadow objects were classified through the shadow intensity, and feature information such as rectangular fit, Gray-Level Co-occurrence Matrix (GLCM) homogeneity and area of each object were calculated for building candidate detection. Then, the final buildings were detected using the direction and distance relationship between the center of building candidate object and its shadow according to the azimuth angle of the Sun. A total of three methods were proposed for the building change detection between building objects detected in each image: simple overlay between objects, comparison of the object sizes according to the elevation angle of the platform, and consideration of direction between objects according to the azimuth angle of the platform. In this study, residential area was selected as study area using high-resolution imagery acquired from KOMPSAT-3 and Unmanned Aerial Vehicle (UAV). Experimental results have shown that F1-scores of building detection results detected using feature information were 0.488 and 0.696 respectively in KOMPSAT-3 image and UAV image, whereas F1-scores of building detection results considering shadows were 0.876 and 0.867, respectively, indicating that the accuracy of building detection method considering shadows is higher. Also among the three proposed building change detection methods, the F1-score of the consideration of direction between objects according to the azimuth angles was the highest at 0.891.

• Korean Journal of Remote Sensing
• /
• v.38 no.6_1
• /
• pp.1445-1462
• /
• 2022

Compact Advanced Satellite 500-4 (CAS500-4), which is scheduled to be launched in 2025, is a mid-resolution satellite with a 5 m resolution developed for wide-area agriculture and forest observation. To utilize satellite images, it is important to establish a precision sensor model and establish accurate geometric information. Previous research reported that a precision sensor model could be automatically established through the process of matching ground control point (GCP) chips and satellite images. Therefore, to improve the geometric accuracy of satellite images, it is necessary to improve the GCP chip matching performance. This paper proposes an improved GCP chip matching scheme for improved precision sensor modeling of mid-resolution satellite images. When using high-resolution GCP chips for matching against mid-resolution satellite images, there are two major issues: handling the resolution difference between GCP chips and satellite images and finding the optimal quantity of GCP chips. To solve these issues, this study compared and analyzed chip matching performances according to various satellite image upsampling factors and various number of chips. RapidEye images with a resolution of 5m were used as mid-resolution satellite images. GCP chips were prepared from aerial orthographic images with a resolution of 0.25 m and satellite orthogonal images with a resolution of 0.5 m. Accuracy analysis was performed using manually extracted reference points. Experiment results show that upsampling factor of two and three significantly improved sensor model accuracy. They also show that the accuracy was maintained with reduced number of GCP chips of around 100. The results of the study confirmed the possibility of applying high-resolution GCP chips for automated precision sensor modeling of mid-resolution satellite images with improved accuracy. It is expected that the results of this study can be used to establish a precise sensor model for CAS500-4.