• Title/Summary/Keyword: 탐사개발

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On the Improvement of Precision in Gravity Surveying and Correction, and a Dense Bouguer Anomaly in and Around the Korean Peninsula (한반도 일원의 중력측정 및 보정의 정밀화와 고밀도 부우게이상)

  • Shin, Young-Hong;Yang, Chul-Soo;Ok, Soo-Suk;Choi, Kwang-Sun
    • Journal of the Korean earth science society
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    • v.24 no.3
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    • pp.205-215
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    • 2003
  • A precise and dense Bouguer anomaly is one of the most important data to improve the knowledge of our environment in the aspect of geophysics and physical geodesy. Besides the precise absolute gravity station net, we should consider two parts; one is to improve the precision in gravity measurement and correction of it, and the other is the density of measurement both in number and distribution. For the precise positioning, we have tested how we could use the GPS properly in gravity measurement, and deduced that the GPS measurement for 5 minutes would be effective when we used DGPS with two geodetic GPS receivers and the baseline was shorter than 40km. In this case we should use a precise geoid model such as PNU95. By applying this method, we are able to reduce the cost, time, and number of surveyors, furthermore we also get the benefit of improving in quality. Two kind of computer programs were developed to correct crossover errors and to calculate terrain effects more precisely. The repeated measurements on the same stations in gravity surveying are helpful not only to correct the drifts of spring but also to approach the results statistically by applying network adjustment. So we can find out the blunders of various causes easily and also able to estimate the quality of the measurements. The recent developments in computer technology, digital elevation data, and precise positioning also stimulate us to improve the Bouguer anomaly by more precise terrain correction. The gravity data of various sources, such as land gravity data (by Choi, NGI, etc.), marine gravity data (by NORI), Bouguer anomaly map of North Korea, Japanese gravity data, altimetry satellite data, and EGM96 geopotential model, were collected and processed to get a precise and dense Bouguer anomaly in and around the Korean Peninsula.

International Legal Regulation on Commercial Space Activity (상업적 우주활동의 국제법적 규제)

  • Lee, Young-Jin
    • The Korean Journal of Air & Space Law and Policy
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    • v.28 no.2
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    • pp.183-221
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    • 2013
  • While in the early stages of space activities only a few states engaged in the use of outer space, as is well known, commercial space activities have grown dramatically in recent years. Both states, state institutions, and international governmental organizations as well as many private enterprises are engaged in such commercial use of outer space by now. This development is not reflected in the present state of space law. The existing international instruments of space law were developed and finalized before this development and thus only provide very few and sometimes unfitting provisions for the commercial use of outer space and particularly the use by private enterprises. Law formulated in an era when the word "privatization" had not even been coined cannot contain potential problems caused by the increasing commercialization of outer space. For the promotion and further development of such commercial use of outer space it is necessary to clarify and establish the legal framework for such use, because participants will need this information for their future investments in this field. The purpose of this paper is to research and make an analysis of the contents and international regulation of international space commerce, which is rapidly proliferating and to review the process of improvement on national legislations relating to the commercialization of outer space in a few main space advanced countries to make the sustainable progress of commercial space activities project in international society. The legal implications of matters such as international commercial launch services, the liability aspects of such services, intellectual property rights, insurance, product liability insurance and materials processing could one day will be subject to regulated by international space law as well as domestic law. In fact, the question of commercialization is linked to the question of sharing benefits of space activities, and this currently is an agenda item in the Legal Subcommittee of UN COPUOS. Most of developed countries have enacted the national legislation for commercial space activities relating to the development of our space as follows : The National Aeronautic and Space Act of 1958 and the Commercial Space Act of 1998 in the United States, Outer Space Act of 1986 in England, Establishment Act of National Space Center of 1961 in France, Canadian Space Agency Act of 1990 in Canada, Space Basic Act of 2008 in Japan, and Law on Space Activity of 1993 in Russia. Becides there are currently three national legislations relating to space development and commercial space activities in Korea as follows : Aerospace Industry Development Promotion Act of 1987, Outer Space Development Promotion Act of 2005, Outer Space Damage Compensation Act of 2008. Commercial space great promise for the utilization and expansion of human outer space activities but aspring commercial actors must recognize that foreign policy, as well as obligations to the international community as a whole, ensure that commercial space activities will not operate in a legal and regulatory vacuum. As commercial space matures the law and accompanying regulation will most certainly evolve and choose to become participants in the inevitable evolution of law and regulation.

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Comparative Research of Image Classification and Image Segmentation Methods for Mapping Rural Roads Using a High-resolution Satellite Image (고해상도 위성영상을 이용한 농촌 도로 매핑을 위한 영상 분류 및 영상 분할 방법 비교에 관한 연구)

  • CHOUNG, Yun-Jae;GU, Bon-Yup
    • Journal of the Korean Association of Geographic Information Studies
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    • v.24 no.3
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    • pp.73-82
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    • 2021
  • Rural roads are the significant infrastructure for developing and managing the rural areas, hence the utilization of the remote sensing datasets for managing the rural roads is necessary for expanding the rural transportation infrastructure and improving the life quality of the rural residents. In this research, the two different methods such as image classification and image segmentation were compared for mapping the rural road based on the given high-resolution satellite image acquired in the rural areas. In the image classification method, the deep learning with the multiple neural networks was employed to the given high-resolution satellite image for generating the object classification map, then the rural roads were mapped by extracting the road objects from the generated object classification map. In the image segmentation method, the multiresolution segmentation was employed to the same satellite image for generating the segment image, then the rural roads were mapped by merging the road objects located on the rural roads on the satellite image. We used the 100 checkpoints for assessing the accuracy of the two rural roads mapped by the different methods and drew the following conclusions. The image segmentation method had the better performance than the image classification method for mapping the rural roads using the give satellite image, because some of the rural roads mapped by the image classification method were not identified due to the miclassification errors occurred in the object classification map, while all of the rural roads mapped by the image segmentation method were identified. However some of the rural roads mapped by the image segmentation method also had the miclassfication errors due to some rural road segments including the non-rural road objects. In future research the object-oriented classification or the convolutional neural networks widely used for detecting the precise objects from the image sources would be used for improving the accuracy of the rural roads using the high-resolution satellite image.

Extraction of Water Body Area using Micro Satellite SAR: A Case Study of the Daecheng Dam of South korea (초소형 SAR 위성을 활용한 수체면적 추출: 대청댐 유역 대상)

  • PARK, Jongsoo;KANG, Ki-Mook;HWANG, Eui-Ho
    • Journal of the Korean Association of Geographic Information Studies
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    • v.24 no.4
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    • pp.41-54
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    • 2021
  • It is very essential to estimate the water body area using remote exploration for water resource management, analysis and prediction of water disaster damage. Hydrophysical detection using satellites has been mainly performed on large satellites equipped with optical and SAR sensors. However, due to the long repeat cycle, there is a limitation that timely utilization is impossible in the event of a disaster/disaster. With the recent active development of Micro satellites, it has served as an opportunity to overcome the limitations of time resolution centered on existing large satellites. The Micro satellites currently in active operation are ICEYE in Finland and Capella satellites in the United States, and are operated in the form of clusters for earth observation purposes. Due to clustering operation, it has a short revisit cycle and high resolution and has the advantage of being able to observe regardless of weather or day and night with the SAR sensor mounted. In this study, the operation status and characteristics of micro satellites were described, and the water area estimation technology optimized for micro SAR satellite images was applied to the Daecheong Dam basin on the Korean Peninsula. In addition, accuracy verification was performed based on the reference value of the water generated from the optical satellite Sentinel-2 satellite as a reference. In the case of the Capella satellite, the smallest difference in area was shown, and it was confirmed that all three images showed high correlation. Through the results of this study, it was confirmed that despite the low NESZ of Micro satellites, it is possible to estimate the water area, and it is believed that the limitations of water resource/water disaster monitoring using existing large SAR satellites can be overcome.

Usefulness of Canonical Correlation Classification Technique in Hyper-spectral Image Classification (하이퍼스펙트럴영상 분류에서 정준상관분류기법의 유용성)

  • Park, Min-Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5D
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    • pp.885-894
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    • 2006
  • The purpose of this study is focused on the development of the effective classification technique using ultra multiband of hyperspectral image. This study suggests the classification technique using canonical correlation analysis, one of multivariate statistical analysis in hyperspectral image classification. High accuracy of classification result is expected for this classification technique as the number of bands increase. This technique is compared with Maximum Likelihood Classification(MLC). The hyperspectral image is the EO1-hyperion image acquired on September 2, 2001, and the number of bands for the experiment were chosen at 30, considering the band scope except the thermal band of Landsat TM. We chose the comparing base map as Ground Truth Data. We evaluate the accuracy by comparing this base map with the classification result image and performing overlay analysis visually. The result showed us that in MLC's case, it can't classify except water, and in case of water, it only classifies big lakes. But Canonical Correlation Classification (CCC) classifies the golf lawn exactly, and it classifies the highway line in the urban area well. In case of water, the ponds that are in golf ground area, the ponds in university, and pools are also classified well. As a result, although the training areas are selected without any trial and error, it was possible to get the exact classification result. Also, the ability to distinguish golf lawn from other vegetations in classification classes, and the ability to classify water was better than MLC technique. Conclusively, this CCC technique for hyperspectral image will be very useful for estimating harvest and detecting surface water. In advance, it will do an important role in the construction of GIS database using the spectral high resolution image, hyperspectral data.

Review of applicability of Turbidity-SS relationship in hyperspectral imaging-based turbid water monitoring (초분광영상 기반 탁수 모니터링에서의 탁도-SS 관계식 적용성 검토)

  • Kim, Jongmin;Kim, Gwang Soo;Kwon, Siyoon;Kim, Young Do
    • Journal of Korea Water Resources Association
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    • v.56 no.12
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    • pp.919-928
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    • 2023
  • Rainfall characteristics in Korea are concentrated during the summer flood season. In particular, when a large amount of turbid water flows into the dam due to the increasing trend of concentrated rainfall due to abnormal rainfall and abnormal weather conditions, prolonged turbid water phenomenon occurs due to the overturning phenomenon. Much research is being conducted on turbid water prediction to solve these problems. To predict turbid water, turbid water data from the upstream inflow is required, but spatial and temporal data resolution is currently insufficient. To improve temporal resolution, the development of the Turbidity-SS conversion equation is necessary, and to improve spatial resolution, multi-item water quality measurement instrument (YSI), Laser In-Situ Scattering and Transmissometry (LISST), and hyperspectral sensors are needed. Sensor-based measurement can improve the spatial resolution of turbid water by measuring line and surface unit data. In addition, in the case of LISST-200X, it is possible to collect data on particle size, etc., so it can be used in the Turbidity-SS conversion equation for fraction (Clay: Silt: Sand). In addition, among recent remote sensing methods, the spatial distribution of turbid water can be presented when using UAVs with higher spatial and temporal resolutions than other payloads and hyperspectral sensors with high spectral and radiometric resolutions. Therefore, in this study, the Turbidity-SS conversion equation was calculated according to the fraction through laboratory analysis using LISST-200X and YSI-EXO, and sensor-based field measurements including UAV (Matrice 600) and hyperspectral sensor (microHSI 410 SHARK) were used. Through this, the spatial distribution of turbidity and suspended sediment concentration, and the turbidity calculated using the Turbidity-SS conversion equation based on the measured suspended sediment concentration, was presented. Through this, we attempted to review the applicability of the Turbidity-SS conversion equation and understand the current status of turbid water occurrence.

Exploration and Development in the Janggun Pb-Zn Mine (장군광산(將軍鑛山)의 탐사(探査)와 개발현황(開發現況))

  • Kho, Suck Jin
    • Economic and Environmental Geology
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    • v.20 no.4
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    • pp.289-303
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    • 1987
  • 당(當) 광산(鑛山)은 1936년(年) 금(金), 은(銀) 광종(鑛種)으로 출원(出願)하였다가 1940년(年) 망간을 추가(追加)하여 망간 광산(鑛山)으로 1975년(年)까지 Mn(30~35%) 110,000여(餘)톤을 생산(生産), 국내생산량(國內生産量)의 70%를 점(占)하였고 1976년(年) Mn광상(鑛床) 하부(下部)에 연(鉛), 아연(亞鉛) 유화광(硫化鑛)을 발견(發見), 현재(現在)까지 Pb十Zn=10% 이상(以上) 원광석(原鑛石) 500,000여(餘)톤을 처리(處理), 연정광(鉛精鑛)(Pb : 62%) 37,000여(餘)톤, 아연정광(亞鉛精鑛)(Zn : 46.5%) 37,000여(餘)톤, 유비광정광(硫砒鑛精鑛)(As : 30%) 5,000여(餘)톤을 생산(生産)하였다. 현재(現在) 일처리(日處理) 220톤 선광장(選鑛場)을 일처리(日處理) 400톤 규모(規模)로 증설계획중(增設計劃中)이다. 당(當) 광산(鑛山)에서 현재(現在)까지 시행(施行)한 갱외시추(坑外試錐)는 75개공(個孔) 18,500여(餘)m, 갱내시추(坑內試錐) 750개공(個孔) 40,000여(餘)m 갱도(坑道) 총연장(總延長) 13,000m에 달(達)하며 지표(地表)(623ML)로 부터 수직(垂直) 300m 하부(下部)까지 갱도(坑道)가 개착(開鑿)되어 있다. 당(當) 광산(鑛山)의 지질(地質)은 여러 조사서(調査書)에 의(依)하여 견해(見解) 차이(差異)를 보여주고 있으나 대체(大體)로 다음과 같은 쪽으로 인정되고 있다. 즉(卽) 본지역(本地域) 루층군(累層群)의 층순(層順)을 하위(下位)로 부터 상위(上位)로 향(向)하여 원남층(遠南層)${\rightarrow}$율리통(栗里統)${\rightarrow}$장산규암층(壯山珪岩層)${\rightarrow}$두음리층(斗音里層)${\rightarrow}$장군석회암층(將軍石灰岩層)${\rightarrow}$동수곡층(東水谷層)${\rightarrow}$재산층(才山層)의 순위(順位)로 보며 장산규암층(壯山珪岩層)과 두음리층(斗音里層)을 조선계(朝鮮系)의 양덕통(陽德統)으로, 장군석회암층(將軍石灰岩層)을 대석회암통(大石灰岩統)으로, 동수곡층(東水谷層)과 함탄층(含炭層)인 재산층(才山層)을 평안계(平安系) 지층(地層)으로 대비(對比)한다. 이들은 본지역(本地域) 북(北)쪽에서는 선(先)캠브리아기(紀)의 원남층(遠南層)과 율리통(栗里統)을 불정합(不整合)으로 덮고 남측(南側)에서는 재산층(才山層)과 원남층(遠南層)이 단층접촉(斷層接觸)하고 있다. 이들 지층(地層)의 주향(走向)은 $N60^{\circ}{\sim}80^{\circ}W$, $N60^{\circ}{\sim}80^{\circ}E$이며 경사(傾斜)는 대체(大體)로 $50^{\circ}{\sim}80^{\circ}N$이며 전체적(全體的)으로 역전(逆轉)된 층서(層序)를 보여주는 바 지질구조(地質構造)에 있어서 단사구조(單斜構造)인지 등사(等斜)습곡의 향사(向斜), 또는 등사(等斜)습곡이 배사구조(背斜構造)인지 아직 밝혀지지 않고 있다. 화성암체(火成岩體)는 본지역(本地域) 서측(西側)에 쥬라기(紀) 춘양화강암(春陽花崗岩)이 불규칙(不規則)한 실입(實入) 접촉면(接觸面)을 보여주며 시대미상(時代未詳)(백악기(白堊紀)?)의 거정화강암(巨晶花崗岩), 반화강암(半花崗岩)이 소암주상(小岩株狀)으로 몇 곳 실입(實入)하고 산성(酸性)~중성(中性)의 맥암(脈岩)과 염기성(鹽基性) 안산암질암(安山岩質岩)이 실입(實入)해 있다. 광상(鑛床)은 장군석회암층(將軍石灰岩層)에 배태(胚胎)되어 있는 열수교대(熱水交代) 연(鉛), 아연(亞鉛), 은등(銀等)의 혼합(混合) 유화광상(硫化鑛床)으로 다량(多量)의 Mn분(分)을 수반(隨伴)하며 지표부(地表部)에 Mn광상(鑛床)을 형성(形成)하고 있다. 광상(鑛床)의 형태(形態)는 괴상(塊狀), 각력(角礫)pipe상(狀), 맥상(脈狀)으로 나타난다. 광상(鑛床)의 성인(成因)과 생성시기(生成時期)에 대(對)하여 많은 논란(論難)이 있다. 즉(卽) 열수교대(熱水交代)냐, 접촉교대(接觸交代)냐, 동시퇴적기원(同時堆積起源)이냐, 또는 생성시기(生成時期)가 쥬라기(紀)인지 백악기(白堊紀)인지에 대해 이론(異論)이 있다. 본지역(本地域) 광상(鑛床)은 남본(南本), 100우(右), 북(北), 유비철(硫砒鐵), 동(東), 서(西), 재남(才南), 재동(才東), 110호(號) 등(等)이 지표(地表) Mn로두광화대(露頭鑛化帶)와 관련(關聯) 명명(命名)된 바 전(前)4자(者)는 하부(下部)에서 유화광상(硫化鑛床)이 확인(確認)되었으나 나머지 후자(後者)에서는 아직 하부(下部)에 유화광상(硫化鑛床)이 확인(確認)되지 않고 있으며 남본광상(南本鑛床)으로 부터 남동(南東) 300여(餘)m 지점에 장군석회암층(將軍石灰岩層)과 동수곡층(東水谷層) 경계부(境界部)에 Fe 55~60% 자철광상(磁鐵鑛床)이 확인(確認)된 바 신례미(新禮美) 자철광상(磁鐵鑛床)과 유사성(類似性)이 있는 것 같아 흥미(興味)롭다. 당(當) 광산(鑛山)의 현재(現在)까지의 탐광(探鑛)은 남본광상(南本鑛床) 지표로두(地表露頭)(Mn) 하부(下部)에서 확인(確認)된 연(鉛), 아연(亞鉛), 은(銀) 유화광체(硫化鑛體) 하부(下部)와 전탐(電探)에 의(依)해 확인(確認)된 북광체(北鑛體), 갱도접근중(坑道接近中)에 확인(確認)된 100우광체(右鑛體), 유비철광체(硫砒鐵鑛體) 등(等)의 하부(下部) 탐광(探鑛)을 주(主)로 하고 지표(地表) Mn로두(露頭) 하부(下部)에 대(對)한 시추탐광(試錐探鑛0을 병행(竝行)하고 있으며 시추(試錐)에 의(依)해서 지표(地表)로 부터 790m 하부(下部)(해발(海拔) 200ML)까지 광화대(鑛化帶)가 확인(確認)되었다. 향후(向後) 탐광방침(探鑛方針)을 확고(確固)히 수립(樹立)하기 위(爲)하여는 광상(鑛床)의 성인구명(成因究明)은 물론(勿論) 광상(鑛床)의 배태조건(胚胎條件)에 있어 지질구조규제(地質構造規制)와 화강암(花崗岩)의 실입상(實入狀)과의 관계(關係), 광액(鑛液)의 통로(通路)에 대(對)한 지질구조(地質構造), 모암(母岩)의 화학(化學) 물리적(物理的) 특성(特性)에 대(對)한 연구(硏究) 검토(檢討)가 었어야 하겠다.

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The Definition of Outer Space and the Air/Outer Space Boundary Question (우주의 법적 지위와 경계획정 문제)

  • Lee, Young-Jin
    • The Korean Journal of Air & Space Law and Policy
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    • v.30 no.2
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    • pp.427-468
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    • 2015
  • To date, we have considered the theoretical views, the standpoint of states and the discourse within the international community such as the UN Committee on the Peaceful Uses of Outer Space(COPUOS) regarding the Air/Outer Space Boundary Question which is one of the first issues of UN COPUOS established in line with marking the starting point of Outer Space Area. As above mentioned, discussions in the United Nations and among scholars of within each state regarding the delimitation issue often saw a division between those in favor of a functional approach (the functionalists) and those seeking the delineation of a boundary (the spatialists). The spatialists emphasize that the boundary between air and outer space should be delimited because the status of outer space is a type of public domain from which sovereign jurisdiction is excluded, as stated in Article 2 of Outer Space Treaty. On the contrary art. I of Chicago Convention is evidence of the acknowledgement of sovereignty over airspace existing as an international customary law, has the binding force of which exists independently of the Convention. The functionalists, backed initially by the major space powers, which viewed any boundary demarcation as possibly restricting their access to space, whether for peaceful or non-military purposes, considered it insufficient or inadequate to delimit a boundary of outer space without obvious scientific and technological evidences. Last more than 50 years there were large development in the exploration and use of outer space. But a large number states including those taking the view of a functionalist have taken on a negative attitude. As the element of location is a decisive factor for the choice of the legal regime to be applied, a purely functional approach to the regulation of activities in the space above the Earth does not offer a solution. It seems therefore to welcome the arrival of clear evidence of a growing recognition of and national practices concerning a spatial approach to the problem is gaining support both by a large number of States as well as by publicists. The search for a solution to the problem of demarcating the two different legal regimes governing the space above Earth has undoubtedly been facilitated and a number of countries including Russia have already advocated the acceptance of the lowest perigee boundary of outer space at a height of 100km. As a matter of fact the lowest perigee where space objects are still able to continue in their orbiting around the earth has already been imposed as a natural criterion for the delimitation of outer space. This delimitation of outer space has also been evidenced by the constant practice of a large number of States and their tacit consent to space activities accomplished so far at this distance and beyond it. Of course there are still numerous opposing views on the delineation of a outer space boundary by space powers like U.S.A., England, France and so on. Therefore, first of all to solve the legal issues faced by the international community in outer space activities like delimitation problem, there needs a positive and peaceful will of international cooperation. From this viewpoint, President John F. Kennedy once described the rationale behind the outer space activities in his famous "Moon speech" given at Rice University in 1962. He called upon Americans and all mankind to strive for peaceful cooperation and coexistence in our future outer space activities. And Kennedy explained, "There is no strife, ${\ldots}$ nor any international conflict in outer space as yet. But its hazards are hostile to us all: Its conquest deserves the best of all mankind, and its opportunity for peaceful cooperation may never come again." This speech seems to even present us in the contemporary era with ample suggestions for further peaceful cooperation in outer space activities including the delimitation of outer space.

Development of Tuna Purse Seine Fishery in Korea and the Countries Concerned (한국(韓國) 및 관련각국((關聯各國)의 다랑어 선망어업(旋網漁業) 발달과정(發達過程))

  • Hyun, Jong-Su;Lee, Byoung-Gee;Kim, Hyoung-Seok;Yae, Young-Hee
    • Journal of Fisheries and Marine Sciences Education
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    • v.4 no.1
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    • pp.30-46
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    • 1992
  • Korea's first exploratory tuna fishing was done with a used longliner in 1957. Then the commercial fishing has been made steady headway since the 1960's and grown up to one of major tuna fishing countries in 1970's. The tuna fishing aimed primarily at acquiring foreign currency, then tuna was exported directly from the overseas fishing base. Tuna, however, has been gradually favored by Koreans as high-proteined foods according to the growth of GNP since the 1970's. In 1980, the canned tuna began to be produced and sold at home. And so the demand of raw tuna for cannaries has steeply increased not only for home but also for abroad, and stimulated the development of tuna purse seine fishery. The author carried out a study on the development of tuna purse seine fishery in Korea and countries concerned-the United States and Japan-because it is recognized to be significant for the further development of this fishery. Just as purse seining was originated in the United States, so tuna purse seining was also pioneered by Californian fishermen in the west coastal waters of the United States (Eastern Pacific Ocean). They started to produce the canned tuna in the early 1900's, and the demand for raw tuna began to be increased rapidly. In those days, tuna was mostly caught by pole-and-line, but the catch amount was far away from the demand. To satisfy this demand, they began to try out fishing tuna by the use of purse seine which had been born in the eastern waters in the 1820's and applied to catch white fishes in the western waters of the United States in those days. Even though their trial was technically successful through severe trial and error, a new problem was raised on the management of tuna resource and the preservation of porpoise which was occassionally caught with tuna. Then the Inter-American Tropical Tuna Commission (IATTC) was established by countries neighboring to the United States in 1950 and they set up the Commission's Yellowfin Regulatory Area (CYRA) and regulated the annual quota for yellowfin. Then, American owners tried to send their seiners to the Western African waters to expand the fishing ground in 1967 and to the Centeral-Western Pacfic in 1974, and the fishing ground was widely expanded. The number of the United States' purse seiners amounted to about 150 in 1980, but the enthusiasm was gradually cooled thereafter and the number of seiner was decreased to 67 in 1986. The landing of tuna by purse seiners in the United States after 1980 maintains 200 thousands M/T or so with a little increase despite the decreasing of domestic seiners. This shows that the landing by foreign seiners are increasing, compared with the landing by domestic seiners are decreasing. In Japan, even though purse seining was introduced in 1880, they had fished tuna by longline and pole-and -line until the tuna purse seining was introduced from the United States again. In the 1960's, Japanese tuna seiners made the exploratory fishing in the South-western Pacific and West African waters with a limited success. In 1971, the government-funded research center "JARMRAC" conducted the exploratory fishing which extended to the Central American waters, the Asia-Pacific Region and the South-western Pacific. It had also much difficulties, till they improved the fishing gear adaptable to the new fishing condition in the South-western Pacific. Japanese government has begun to licence 32 single seiners and 7 group seiners since 1980 and their standard has lasted up to now. The catch in the Pacific Islands Region amounted to 160 thousands M/T in 1986. Korea's tuna purse seine fishery was originated in 1971 by Jedong Industrial Co., Ltd. with three used tuna purse seiners purchased from the United States, and they began to fish in the Eastern Pacific, but failed owing to the superannuation of vessel and the infancy of fishing technique. The second challenge was done by Dongwon Industrial Co., Ltd. in 1979, with one used seiner purchased from the United States, and started to fish in the Eastern Pacific. Even though the first trial was almost unsuccessful but they could obtain the noticeable success by removing the vessel to the South-western Pacific in 1980. This success stimulated the Korean entherprisers to take part in this fishery, and the number of Korean tuna purse seiners has been increased rapidly in accordance with the increased demand for raw tuna. The number of vessels actually at work amounted to 36 in 1990 and they operate in the South-western Pacific. The annual catch of tuna by purse seiners amounted to 170 thousands M/T in 1990 and ranked to one of the major tuna purse seining countries in the world.

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