• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.63-73
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• 2021

This paper presents a algorithm for automatic target recognition robust to the influence of the flame in order to track the target by EOTS(Electro-Optical Targeting System) equipped on UAV(Unmanned Aerial Vehicle) when there is aerial target or marine target with flame at the same time. The proposed method converts infrared images of targets and flames into a gradient vector field, and applies each gradient magnitude to a polynomial curve fitting technique to extract polynomial coefficients, and learns them in a shallow neural network model to automatically recognize targets and flames. The performance of the proposed technique was confirmed by utilizing the various infrared image database of the target and flame. Using this algorithm, it can be applied to areas where collision avoidance, forest fire detection, automatic detection and recognition of targets in the air and sea during automatic flight of unmanned aircraft.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.2
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• pp.25-33
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• 2002

We were trying to understand indirectly the range of the discharge from the Nakdong with the dispersion of suspended solid(SS) related to the amount of discharge from river in this study. The range of dispersion of SS from the Nakdong was estimated using satellite remote sensing and numerical modeling. The stream field with two dimensional and numerical model using the condition of integrated depth was calculated. According to the results, the streamline flowed from Busan to the Jinhae Bay and Geojae Island. at the flood. The situation at the ebb was totally changed. The streamline flowed out Busan from the Bay. The velocity in offshore was faster than one at coastal water of the Nackdong. Residual current which was averaged during 12hours dominantly appeared the dominant direction from the southwestern part of the Nackdong to the northeastern part of it. The eastward current appeared at the eastern coast of Gaduck Is. Base on the results of the velocity field, the quantifying of the dispersion of SS was estimated by the method of numerical tracer related to the Lagrangian method. The significant range of the dispersion of the SS from the Nackdong was from the eastern coast of Gaduck Is, to the coastal areas of Busan, Korea. The estimated range of the dispersion of the SS using the SeaWiFS and Landsat satellite data was similar to the estimated results using the numerical model.

• Journal of Navigation and Port Research
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• v.44 no.4
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• pp.305-311
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• 2020

Rising sea levels along the coast from global warming causes the increase of wave energy along the coast. This rise in sea levels results in relatively deep water levels, which would incur the loss of sand that had not occurred in the past from erosion in coastal areas. Generally, it has been challenging to protect against coastal erosion, and the slope, cross-sectional shape, and materials are selected for the site conditions depending on the change in external forces. However, the application of counter measures based on insufficient understanding of the phenomenon is causing various damage, indicating the need for technological development and converging technologies to improve credibility. In this study, we developed eco-friendly permeable biopolymer concrete blocks to control the coastal erosion by using the Bio-Coast, an effective porous structure that mitigates the destructive erosion caused by the rising sea levels. The hexagonal design of Bio-Coast was derived from the honeycomb, columnar joints, and clover, which are durable and stable structures in nature, and the design was changed to apply bumps on the Bio-Coast filling in the form of a clover to reduce wave overtopping and run-up. Applying the field condition of beaches on the east coast of Korea, the block weight and size were decided and the prototype blocks were manufactured and are ready for field placement. In particular, it is intended to protect coastal areas from destructive erosion by natural and artificial external forces, and to extend the design to river,s lakes, and natural walking trails, to improve the efficiency of quality control and process control through the use of blocks.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.281-291
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• 2010

To estimate the mesh selectivity of monofilament and multifilament gill net for Marbled sole, Pleuronectes yokohamae, the field testes were carried out 12 times with five different mesh sizes (86.6, 101.0, 121.2, 137.7, 151.5mm) in the western sea of Korea, 2007-2009. The master curve of selectivity was estimated by the extended Kitahara's method. In the field testes, the total number of species and catch were 26 and 987, respectively. The catch number of marbled sole was 728 and occupied 73.8% in total catch. The optimum values of l/m for 1.0 of retention probability in monofilament and multifilament gill net were estimated 0.288 and 0.307, respectively and l/m was estimated to be 0.189, 0.203, 0.213, 0.222 and 0.230 in case of monofilament gill net and 0.171, 0.191, 0.205, 0.216 and 0.227 in case of multifilament gill net when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively. The 0.5 selection range of multifilament gill net was wider about 1.5 times than that of monofilament gill net according as multifilament gill net was 0.216 and monofilament gill net was 0.148. So the multifilament gill net has a low selectivity than that of the monofilament gill net. To estimate the optimum mesh size on first maturity length 19.5cm of marbled sole, the retention probability value of 0.1 was adopted in consideration of using the gill net for marbled sole at present. The optimum mesh size were estimated to be 103.2mm and 114.0mm in monofilament gill net and multifilament gill net, respectively, on first maturity length 19.5cm of marbled sole.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.472-482
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• 2019

This paper describes the stabilization of underwater TAS winch system Deploy/Recover operation performance. TAS winch installed on the stern of submarine performs to deploy/recover sensor, towing cable and rope tail which is deployed from the stern and separated from submarine itself. Also TAS winch provides transmission path of power to the sensor and data transmitting/receiving path which data are acquired from underwater environment like sound, depth and temperature. At the step of TAS winch evaluation test, sporadic standstill and rotating speed oscillation phenomenon were occurred. Winch motor provides the available torque to deploy/recover TAS and root cause analysis to the winch motor was done to find exact reason to sporadic malfunction. When winch motor was disassembled, eccentricity of rotor, slip-ring and the other composition part for winch motor were found. These might cause magnetic field distortion. To make TAS winch system more stable and block magnetic field distortion, this paper suggests methods to enhance fixing status installed in winch motor. For reliable data acquisition for TAS winch operation, the deploy/recover function of the improved type of TAS winch was verified in LBTS making similar condition with sea status. At the end of stage, improved type of TAS winch was tested on some functions not only deploy/recover function, but sustainability of TAS operation on specific velocity, steering angle of submarine in the sea trial. Improved type of TAS winch was verified in accordance with design requirement. Also, validity of suggested methods were verified by the sea trial.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.1
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• pp.44-55
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• 1998

Imgok creek is the most severly polluted one out of the streams which have been being polluted by acid drainages from the abandoned coal mines in the Gangdong-Myeon area, the central part of the so called Gangreung coal field. Imgok creek is being mainly polluted by the drainage from Youngdong coal mine, which supplies such pollutants as Mg, Fe, Al, Si, Ca, Mn, and SO$_4$as major dissolved components and Cr, Co, Ni, Cu, Zn, Rb, Sr, Cd, Pb, and U as minor dissolved components. After the influx, the pollutants migrate mainly as dissolved solid, rather than as suspended solids along Imgok creek. The suspended solids in Imgok creek are very rich in Fe and Al, indicating that they mainly consist of the precipitates of present and past from the polluted water. Most of the dissolved components in the stream waters of Imgok creek removed from the aqueous phase by precipitation and dilution before reaching the East Sea, so that water quality of the downstreams of Imgok creek is very similar to that of unpolluted tributaries. It suggests that Imgok creek itself is now being severly polluted by the acid drainages from the abandoned coal mines, but the East Sea is relatively safe from the same pollution. The estuary and sea waters around the Goonseon estuary, which accepts Imgok creek water, certainly show no significant difference in chemical compositions from the mean oceanic water. The bottom sediments at the sampling sites of the sea waters also show no significant trend of their component variation, especially the variations of Fe, SO$_4$ and Al concentrations. These facts again supper that the acid mine drainage is not considerablly polluting the East Sea. However, the tributaries supplying the fresh water to the Imgok creek will be certainly polluted by the acid mine drainage as time passes and pollutants will have more chance to migrate in significant amount to the downstream area, which all can be a real threats to the East Sea on the pollution possibility. Therefore, it is suggested that urgently required are not only water quality and environmental improvement of the severely polluted Imgok creek but also preparation of the measures on the possible future pollution of the East Sea by the acid drainage from the abandoned coal mines in the area, while the East Sea is still not much affected by the pollution of the same kind.

• Journal of Fisheries and Marine Sciences Education
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• v.3 no.2
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• pp.73-82
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• 1991

In recent years, the communication and the trade between the Republic of Korea(South Korea) and the Communist bloc has been activated. The simultaneous entrance of South Korea and North Korea to the United Nations will accelerate the political dialogue and also the trade which is indirectly carried out through a third country at present will be turned into direct way. Fisheries products are also treated as one of the important trade goods and there is a hopeful prospect that the amount of trade will be steeply increased in the near future. Furthermore, there is a great possibility of development up to the joint utilization of fishing grounds or the joint investment in fisheries projects. Concerning such points, since it is very much important to understand the present status of fisheries in North Korea, the author made a study on this field as requested by the Board of Unification, and report a part of the study here. The prominent character of North Korea's ruling sea area is that the sea is completely separated into two regions-the East Sea Region and the West Sea Region-and no continuity exists between them. The East Sea Region locates in the fringe of the biggest fishing ground of the world-the North Pacific Ocean-and very rich in resources not only warm water fishes but also cold water fishes. Especially alaska pollack, Theragra chalcogramma, is caught abundantly in this region. Contrary to that, fishing activity in the West Sea Region seems to be interrupted in winter. Even though some valuable warm water fishes-yellow corvenia, Pseudosciaena manchurica, and hair tail, Trichiurus lepturus, and so forth-come to this region from spring to summer along the coast line of this region for spawning, and vigorous fishing activity is carried out. But the most of them migrate southward to the neighboring waters of Cheju Island for wintering from autumn to winter, and so the fishing activity in this region seems to be interrupted greatly during winter. The total number of fishing boats in North Korea is estimated at 36 thousand and the rate of mechnization at about 70% compared with 99 thousand and 78% in South Korea. North Korea proclaimed an exclusive economic zone of 200 nautical miles in 1977. Specific character of this zone is setting of military boundary zone, up to 50 miles from the base line in the East Sea Region and also it covers whole region of the economic zone in the West Sea Region. Especially in the East Sea Region she set up a straight base line which can not be permissible by the international law. North Korea's statistics on fisheries product has not been announced officially on account of her unique isolationism, but it can be estimated through several data procured. At the first, the amount of fisheries products in the North Korea is reported as about 1.7 million ${\frac{M}{T}}$ by Fisheries Statistics which issued by the FAO in 1987, but a North Korea's trade organization announced the amount as 3.5 million ${\frac{M}{T}}$ in 1988. The former seems to be underestimated and the latter must be an exaggeration. According to Chikuni, who is a Japanese worker for FAO, prepared the unofficial statistics based on the evidence which he collected through the fineries development plan of the FAO/UNDP, and estimated the mean amount between 1982 and 1984 was 2.4 million ${\frac{M}{T}}$ or so. The Board of Unification estimated on the basis of various factors that the amount was 2.2 million ${\frac{M}{T}}$ or so in 1987 and in 1988. This seems to be the most reasonable. To solve the chronic lack of foreign currency, North Korea makes effort on the development of fisheries, and has even aimed fisheries product at 11 million ${\frac{M}{T}}$ by 1993, but this target looks unrealistic under the present circumstances. Somehow, we can exploit her extreme policy which has gone so far as to establish such an excessive and impractical target. Nevertheless this will be helpful to promote the joint development of the fishery activity between South Korea and North Korea.

• Journal of the Korean earth science society
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• v.44 no.1
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• pp.13-35
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• 2023

Ocean currents play the most important role in causing and controlling global climate change. The water depth of the Yellow Sea is very shallow compared to the East Sea, and the circulation and currents of seawater are quite complicated owing to the influence of various wind fields, ocean currents, and river discharge with low-salinity seawater. The Yellow Sea Warm Current (YSWC) is one of the most representative currents of the Yellow Sea in winter and is closely related to the weather of the southwest coast of the Korean Peninsula, so it needs to be treated as important in secondary-school textbooks. Based on the 2015 revised national educational curriculum, secondary-school science and earth science textbooks were analyzed for content related to the YSWC. In addition, a questionnaire survey of secondary-school science teachers was conducted to investigate their perceptions of the temporal variability of ocean currents. Most teachers appeared to have the incorrect knowledge that the YSWC moves north all year round to the west coast of the Korean Peninsula and is strong in the summer like a general warm current. The YSWC does not have strong seasonal variability in current strength, unlike the North Korean Cold Current (NKCC), but does not exist all year round and appears only in winter. These errors in teachers' subject knowledge had a background similar to why they had a misconception that the NKCC was strong in winter. Therefore, errors in textbook contents on the YSWC were analyzed and presented. In addition, to develop students' and teachers' data literacy, class materials on the YSWC that can be used in inquiry activities were developed. A graphical user interface (GUI) program that can visualize the sea surface temperature of the Yellow Sea was introduced, and a program displaying the spatial distribution of water temperature and salinity was developed using World Ocean Atlas (WOA) 2018 oceanic in-situ measurements of water temperature and salinity data and ocean numerical model reanalysis field data. This data visualization materials using oceanic data is expected to improve teachers' misunderstandings and serve as an opportunity to cultivate both students and teachers' ocean and data literacy.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.4
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• pp.340-345
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• 1995

Dispersion characteristics of surface discharge heat water in shallow region are investigated for coastal power plant with nearly constant depth of 20 meters by observing the seasonal depthwide temperature in several stations, which give or precise horizontal distribution and vertical structure of heat water. Surface discharged heat water in shallow coast in the Yellow Sea relies mainly on ambient tidal flow. so it behaves as free jet when the ambient now is strong and shows plumelike behavior during stagnant tide. According to observation the neat field region is estimated as 200-300 meters and shows distinct vertical profile and exponentially decreasing pattern from discharge point for this region. But there are no remarkable vertical distortion of temperature beyond 800 meters even though it is discharged from surface. Characteristic length scale model, CORMIX3, is applied and compared with the field date Overall tendency of CORMIX3 results resemble well with field data especially in near field and intermediate region.

• Journal of KIEE
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• v.11 no.1
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• pp.32-40
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• 2001

This paper presents the detailed statistics on radiation field signatures associated with multiple-intracloud lightning discharges. A transient signal recording system was used to measure the electric and magnetic fields produced by lightning flashes. The measurements were made in th summers of 1995 through 1999, and the location of the observation station was in Inchon on the coast of the Yellow Sea in Korea(37$^{\circ}$25'N, 126$^{\circ}$ 39'E). Most of lightning flashes typically contains between two and five strokes. The individual intracloud stork radiation fields were the bipolar pulse. On the average, the ratio of the peak of the second stroke to the first stroke peak was 75.1$\pm$40.1% for the negative, and a fraction of the subsequent stroke peaks were higher than the first stroke peak. The greater the number of the subsequent stroke order, less time separations between strokes were produced. The mean of the depth of the dip was 81.2$\pm$27.9% for the positive polarity and 75.9$\pm$24.4% for the negative. The depth of the dip increased for the positive bipolar pulses and decreased for the negative as the number of the stroke order increased.