• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1257-1271
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• 2022

Recently, many Earth observation optical satellites have been developed, as their demands were increasing. Therefore, a rapid preprocessing of satellites became one of the most important problem for an active utilization of satellite images. Satellite image matching is a technique in which two images are transformed and represented in one specific coordinate system. This technique is used for aligning different bands or correcting of relative positions error between two satellite images. In this paper, we propose an automatic image matching method among satellite images with different ground sampling distances (GSDs). Our method is based on improved feature matching and robust estimation of transformation between satellite images. The proposed method consists of five processes: calculation of overlapping area, improved feature detection, feature matching, robust estimation of transformation, and image resampling. For feature detection, we extract overlapping areas and resample them to equalize their GSDs. For feature matching, we used Oriented FAST and rotated BRIEF (ORB) to improve matching performance. We performed image registration experiments with images KOMPSAT-3A and RapidEye. The performance verification of the proposed method was checked in qualitative and quantitative methods. The reprojection errors of image matching were in the range of 1.277 to 1.608 pixels accuracy with respect to the GSD of RapidEye images. Finally, we confirmed the possibility of satellite image matching with heterogeneous GSDs through the proposed method.

• Journal of Bio-Environment Control
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• v.31 no.1
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• pp.1-7
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• 2022

Strawberry is a stand-out cultivating fruit in Korea. The optimum production of strawberry is highly dependent on growing environment. Smart farm technology, and automatic monitoring and control system maintain a favorable environment for strawberry growth in greenhouses, as well as play an important role to improve production. Moreover, physiological parameters of strawberry plant and it is surrounding environment may allow to give an idea on production of strawberry. Therefore, this study intends to build a machine learning model to predict strawberry's yield, cultivated in greenhouse. The environmental parameter like as temperature, humidity and CO₂ and physiological parameters such as length of leaves, number of flowers and fruits and chlorophyll content of 'Seolhyang' (widely growing strawberry cultivar in Korea) were collected from three strawberry greenhouses located in Sacheon of Gyeongsangnam-do during the period of 2019-2020. A predictive model, Lasso regression was designed and validated through 5-fold cross-validation. The current study found that performance of the Lasso regression model is good to predict the number of flowers and fruits, when the MAPE value are 0.511 and 0.488, respectively during the model validation. Overall, the present study demonstrates that using AI based regression model may be convenient for farms and agricultural companies to predict yield of crops with fewer input attributes.

• Journal of Appropriate Technology
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• v.7 no.1
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• pp.51-58
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• 2021

This study proposes the design and implementation of a low-cost emergency ventilator which can be helpful during the COVID-19 pandemic where the supply of automatic ventilators is not smooth compared with the urgent demand worldwide. Easy implementation and lower price were made possible by using AMBU-bag and off-the-shelf embedded micro-controller board. Moreover, while 3D printing is used by companies and experts around the world to build prototype hardware, materials which are readily available from surrounding environments so that people in countries where it is difficult to access many advanced technologies could manufacture the system. The design features AMBU-bag automation, not use 3D printing, and it can contrl speed. By allowing speed control, ventilation can be performed according to the conditions of the patient being used. A complementary point in the study is that it is difficult to fix the start point of the wiper motor used first. A method for complementing this is a method for replacing the brush DC motor with a position feedback function. Secondly, the AMBU-bag may wear out in the long-term process of compressing the AMBU-bag because the arm and the fixing frame are made of wood. To complement this, the part of fixing frame and arm parts that the AMBU-bag touches need to be wrapped in a material such as silicon to minimize friction.

• Science of Emotion and Sensibility
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• v.24 no.2
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• pp.25-38
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• 2021

The aim of this study is to protect workers and pedestrians from accidents at night or bad weather by attaching optical fiber to existing safety clothing that is made only with fluorescent fabrics and retroreflective materials. A safety vest was designed and manufactured by applying optical fiber, and energy-harvesting technology was developed. The safety vest was designed to emit light using the automatic flashing of optical fibers attached to the film, and an energy harvester was manufactured and attached to drive the light emission of the optical fiber more continuously. As a result, first, the vest wearer' body was recognized from a distance through the optical fiber and retroreflection, which helped prevent accidents. Thus, this concept helps in saving lives by preventing accidents during night-time work on the roadside or activities of rescue crew and sports activities, or by quickly finding the point of an accident with a signal that changes the optical fiber light emission. Second, to use the wasted energy, a piezoelectric-element power generation system was developed and the piezoelectric-harvesting device was mounted. Potentially, energy was efficiently produced by activating the effective charging amount of the battery part and charging it auxiliary. In the existing safety vest, detecting the person wearing the vest is almost impossible in the absence of ambient light. However, in this study, the wearer could be found within 100 m by the light emission from the safety vest even with no ambient light. Therefore, in this study, we will help in preventing and reducing accidents by developing smart safety clothing using optical fiber and energy harvester attached to save lives.

• Korean Journal of Remote Sensing
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• v.39 no.1
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• pp.77-86
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• 2023

Ship detection is widely used in areas such as maritime security, maritime traffic, fisheries management, illegal fishing, and border control, and ship detection is important for rapid response and damage minimization as ship accident rates increase due to recent increases in international maritime traffic. Currently, according to a number of global and national regulations, ships must be equipped with automatic identification system (AIS), which provide information such as the location and speed of the ship periodically at regular intervals. However, most small vessels (less than 300 tons) are not obligated to install the transponder and may not be transmitted intentionally or accidentally. There is even a case of misuse of the ship'slocation information. Therefore, in this study, ship detection was performed using high-resolution optical satellite images that can periodically remotely detect a wide range and detectsmallships. However, optical images can cause false-alarm due to noise on the surface of the sea, such as waves, or factors indicating ship-like brightness, such as clouds and wakes. So, it is important to remove these factors to improve the accuracy of ship detection. In this study, false alarm wasreduced, and the accuracy ofship detection wasimproved by removing wake.As a ship detection method, ship detection was performed using machine learning-based random forest (RF), and convolutional neural network (CNN) techniquesthat have been widely used in object detection fieldsrecently, and ship detection results by the model were compared and analyzed. In addition, in this study, the results of RF and CNN were combined to improve the phenomenon of ship disconnection and the phenomenon of small detection. The ship detection results of thisstudy are significant in that they improved the limitations of each model while maintaining accuracy. In addition, if satellite images with improved spatial resolution are utilized in the future, it is expected that ship and wake simultaneous detection with higher accuracy will be performed.

• Journal of Platform Technology
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• v.10 no.2
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• pp.10-19
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• 2022

Moving assistant devices for people who are difficult to move are becoming electric-powered and automated. These moving assistant devices are not suitable for moving stairs at which the height between floor surfaces is different because these devices are designed and manufactured for flatland moving. An electric-powered and automated moving assistant device should change direction or stop when it approaches stairs in a movement direction. If the user or automatic control system does not change direction or stop in time, a moving assistant device can roll over or collide with stairs. In this paper, we propose a stairs detection method by using oblique distance measured by one sensor tilted to flatland. The method proposed in this paper can detect upward or downward stairs by using a difference between a predicted and measured oblique distance in considering a tilted angle of a sensor for measuring an oblique distance and installation height of the sensor on a moving object. Before the device enters a stairs region, if our proposed method provides information about detected stairs to a device's controller, the controller can do adequate action to avoid the accident.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1059-1066
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• 2021

In Korea, the importance of marine activities is great, and automatic weather observation facilities are operating on land to investigate abnormal weather phenomena caused by industrialization; however, the number of facilities at sea is insufficient. Marine survey ships are operated to establish marine safety information, but there are many places where marine survey ships are difficult to access and operating costs are high. Therefore, a small, unmanned vessel capable of marine surveys must be developed. The sail has a significant impact on the sailing performance, so much research has been conducted. In this study, the camber effect, which is a design variable of the twin curvy sail known to have higher aerodynamic performance than existing airfoil shapes, was investigated. Flow analysis results for five cases with different camber sizes show that the lift coefficient is highest when the camber size is 9%. Curvy twin sails had the highest lift coefficient at an angle of attack of 23° because of the interaction of the port and starboard sails. The port sail had the highest lift coef icient at an angle of attack of 20°, and the starboard sail had the lowest lift coef icient at an angle of attack of 15°. In addition, the curvy twin sail had a higher lift coefficient than NACA 0018 at all angles of attack.

• Journal of Navigation and Port Research
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• v.46 no.4
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• pp.313-320
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• 2022

The light buoy installed on the sea is always flexible, because it is affected by the weather as well as passing vessels. The position of the light buoy can be cached through the AtoN AIS (Automatic Identification System) and RTU (Remote Terminal Unit). This study analyzed the position data of the light buoys for the last five years (2017-2021), as well as the distribution of the light buoys within the maximum separated position. As a result, there was a basic error of 17.9% in the position data. Additionally, the separated position error of 197 light buoys to be analyzed was 70.64%, and the AtoN RTU was worse than the AtoN AIS by equipment. On the other hand, as a result of the plotting the position data of the light buoy, it was classified into four types. The most common percussion center type, the percussion center dichotomous type in which the position is divided into two zones based on the chimney, the central movement type with a fluctuating center, and the drag type, in which the position is deviated from the center for a certain period. Except for Type-1, the type was determined according to the position at which the light buoy was installed. This study is the first to analyze the position data of the light buoy, and it is expected that it will contribute to the improvement of the quality of the position data of the light buoy.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.151-151
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• 2023

본 연구는 호우(heavy rain) 발생 시 대기 중 미세먼지(particulate matter, PM) 저감효과를 규명하고 강우 지속에 따른 빗물 수질(pH, 전기전도도(electrical conductivity, EC), 수용성 이온) 분석을 통해 대기 중 PM이 빗물 수질에 미치는 영향을 평가하였다. 2020년 3월부터 2021년 2월까지강우 강도(7.5 mm/h)를 기준으로 총 6회의 강우를 대상으로 하였으며 빗물 샘플은 집수장치를 통해 50 mL를 연속적으로 수집하여 수질을 분석하였다. 대기 중 PM_2.5 (≤ 2.5 ㎛ in diameter) 및 PM₁₀ (≤ 10 ㎛ in diameter) 농도는 기상청 내 부산 남구 대연동 관측소의 automatic weather system (AWS)에서 측정된 일평균 자료를 이용하였다. 강우에 따른 대기 중 PM의 저감효율은 상대적으로 PM₁₀에서 뚜렷하게 나타났으며, 특히 강우 강도 7.5 mm/h 이상(유형 1)의 호우 발생 시60% 이상의 저감효율을 보였다. 반면, 강우 강도 7.5 mm/h 이하(유형 2)일 때는 10% 이하의 저감효율을 보였으며, 강우 지속에 따라 대기 중 PM₁₀ 농도가 증가하는 경향을 보이기도 하였다. 총108개의 빗물 샘플 수질을 분석한 결과, 유형 1의 경우 초기 빗물의 평균 EC는 58.5 µS/cm으로 상대적으로 높았으며 대기 중 PM₁₀과 양의 상관관계(r = 0.99)를 보였고 평균 pH는 4.3으로 산성도가 높게 나타났으며 대기 중 PM₁₀과 음의 상관관계(r = -0.99)를 보였다. 반면, 유형 2의 경우 대기 중 PM₁₀과 EC (r = -0.56) 및 pH (r = -0.41) 간 뚜렷한 상관관계가 나타나지 않았다. 또한 강우가 지속됨에 따라 EC와 수용성 양이온(Na⁺, Mg²⁺, K⁺, Ca²⁺, NH₄⁺) 및 음이온(Cl^-, NO₃^-, SO₄^2-)의 농도는 지속적으로 감소하는 경향을 보였으나 pH의 경우 강우 강도에 따라 증감의 경향이 다르게 나타났다. 유형 1의 경우 강우 지속에 따라 pH가 증가하여 산성도가 낮아졌으나 유형 2는 pH의 증감 형태를 뚜렷하게 확인하기 어려웠다. 연구 결과를 통해 강우 초기 높은 강도로 강우가 지속될 경우 대기 중 PM₁₀이 빗물 수질에 영향을 미칠 수 있는 것으로 판단되며, 이에 따라 호우 발생 시 강우가 대기 중 오염물질을 지표면으로 유입시킬 수 있는 매개체로 작용할 수 있음을 지시한다.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.306-313
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• 2023

Realistic and graphics-based virtual reality content is based on 360-degree videos, and viewport extraction through the viewer's intention or automatic recommendation function is essential. This paper designs a viewport extraction system based on multiple object tracking in 360-degree videos and proposes a parallel computing structure necessary for multiple viewport extraction. The viewport extraction process in 360-degree videos is parallelized by composing pixel-wise threads, through 3D spherical surface coordinate transformation from ERP coordinates and 2D coordinate transformation of 3D spherical surface coordinates within the viewport. The proposed structure evaluated the computation time for up to 30 viewport extraction processes in aerial 360-degree video sequences and confirmed up to 5240 times acceleration compared to the CPU-based computation time proportional to the number of viewports. When using high-speed I/O or memory buffers that can reduce ERP frame I/O time, viewport extraction time can be further accelerated by 7.82 times. The proposed parallelized viewport extraction structure can be applied to simultaneous multi-access services for 360-degree videos or virtual reality contents and video summarization services for individual users.