• Title/Summary/Keyword: Late middle age

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Study on the Metallogenic Classification Relating to Igneous Activity in the Ogcheon Geosynclinal Zone, Korea (옥천지향사대(沃川地向斜帶)의 화성활동(火成活動)에 의한 광화작용(鑛化作用)의 유형(類型)에 관(關)한 연구(硏究))

  • Lee, Dai Sung;Chi, Jeong Mann;Lee, Dai Woon
    • Economic and Environmental Geology
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    • v.13 no.3
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    • pp.167-184
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    • 1980
  • The granitic plutons associated with Ogcheon geosynclinal zone can be grouped into three different subzones; SE-Subzone for the migmatitic and schistose granites of the southeast margin, 101-181m.y. old; NW-Subzone for those of the northwest margin, 112-163m. y. old; and C-Subzone for those of central part of the zone, 63-183m.y. old. The intrusives in C-Subzone are further subdivided into the older, adamellite to granodiorite (148-183m.y. old) and the younger, perthitic granites (63-106m,y. old). The metallogenic distribution of South Korea suggests that, in the Ogcheon Zone, it is possible to delineate an elongated polymetallogenic province in the general orientation of the zone intimately related with the migmatite and plutonic zones mentioned. Moreover, the mineralization in the province was basically controlled by the patterns of local geology involving country rocks and related igneous bodies, that permit subdivision of the province into the following three parts: Northeast (NE) Province consists dominantly of thick Paleozoic calcareous sediments; Middle (M) Province is characterized by predominant argillaceous and partly calcareous sediments of Precambrian to Late Paleozoic age; and Southwest (SW) Province consisting mainly of volcanic and arenaceous sediments of Mesozoic age. The three different plutonic zones with three different country rock provinces above mentioned make a combination which consists of nine classes. Each class can be assumed to be characterized by specific mineralization type. In order to classify the mineralization types, the present study sampled twenty six ore deposits and mineralized areas in Ogcheon zone as shown figure 2; eight ore deposits from plutonic SE-Subzone, ten from the plutonic NE-Subzone and eight from the plutonic C-Subzone. The characteristics of the classes are as follows: NE-SE is predominant in Au-Ag vein and Sn-migmatite of katazonal occurrence; NE-C is most productive in Pb-Zn and remarkable in Fe contact deposit in mesozone and partly Pb-Zn-Cu skarn in limestone and subordinate in mesozone and partly Pb-Zn pipes; M-SE is considerable in Au-Ag vein and rare elements (Nb, Ta, etc.) of pegmatite; M-C is predominant in F-veins in epizone and Mo-W, Fe, Cu veins occur in replacement type; M-NW is productive in Fe metamorphic and skarn types, partly remarkable in Cu, Pb-Zn contact; SW-SE is barren in mineralization related to Jurassic igneous rocks; SW-C is predominant in alunite and pyrophyllite in tuffs; and SW-NW is scarece in Pb-Zn, Cu, As and Au-Ag veins.

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Study on the Gathering Effects of Anchovy Scoop Net in the neighboring waters of the Cheju Island (제주도 근해 멸치 분기초망의 집어효과에 관한 연구)

  • SOHN Tae-Jun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.21 no.3
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    • pp.184-192
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    • 1988
  • Anchovy, Engraulis Japonica were caught by scoop net with fishing lamp in the surrounding water of Cheju and Seogwipo, and their gathering depth, gathering effects, change of catch by the age of the moon and submarine illumination were investigated from May to August 1985. Fish finder (SR-385) and fishing lamp (1 Kw incandescent) were set up at one meter of starboard of scoop net and one meter ahead of the prow together with two meters above the water surface respectively. The submarine illumunation was measured at 2m interval to both vertical direction of 0~18m and horizontal direction of 0~12m form the standard point which is to be 0.1m depth right under the fishing lamp. The catch of anchovy by scoop net was almost $90\%$ of total amount during the early period and the late period in moon age while as low as $10\%$ only was cought during the middle period. The catching depth of anchovy shoals by scoop net with fishing lamp was approximately 2~5m and submarine illuminations were 20~42 Lux, 24~48 Lux in Cheju and Seogwipo respec lively. Submarine illumination which could be cought by scoop net with fishing lamp should be 7~12 times lighter than before gathering since the shoals swiming at 10~15m depth which is 1.7~7 Lux illumination made by 1 Kw. AC 100V incandescent lamp, a surface gathering lamp of 2m high above anchovy scoop net came up to 2~5m depth which is 20~42 Lux illumination. The catching depth of anchovy by scoop net was 2~3m and this could be increased to 4m even though the AC voltage was decreased from 100V to 80V at final fishing stage.

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Comparison of Meal Management Attitudes among Housewives between in Industrial Complex and in Non-Industrial Complex on Ansan City in Korea (일부 공단 지역 가정 어머니의 식생활 관리 태도 비교)

  • 남숙연;김선효
    • Journal of the Korean Home Economics Association
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    • v.40 no.4
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    • pp.167-178
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    • 2002
  • This study was carried out to compare the meal management attitudes among the mothers(41 years of age) who had middle school students between in industrial complex and in non-industrial complex. The subjects of each group were composed of 192 mothers Living in Ansan city in Korea, and this study was performed by self-administered questionnaire. The results of the present study were as follows: (1) Monthly family income and education level of parents were lower in industrial complex-family(ICF) than in non-industrial complex-family (NICF). The mean age of mothers and family size were similar in two groups, but the frequency of mothers employed was higher in ICF than in NICF Most mothers in ICF worked as a manual- or skilled-laborer. (2) The mothers in ICF tended to have less positive attitude in sewing balanced meals to their families than those in NICF. The score of nutritional knowledge was lower in mothers in ICF than those in NICF. (3) The percentage of expense for purchasing staple foods to total expense of foods tended to be higher in ICF than in NICF. Engel's coefficient was higher, and the frequency and expense for eating out was lower in ICF than in NICF (4) The mothers in ICF did not try to use their time and energy efficiently for meal management. (5) The mothers in ICF were less active in sewing the pleasurable meals including the provision of various cooking methods, flavors, and temperatures, to their families, than those in NICF. Above findings show that family environment such as industrial complex-families and non-industrial complex-families influences the meal management attitudes of mothers. The mothers in ICF had a less positive altitudes for scientific meal managements than those in NICF even though they had the limited resources including money, time and energy for meal management because most mothers in ICF had a job that were paid low salary and finished irregularly or late. Therefore, these results underscore the need to provide the sound nutritional education for the mothers in ICF with respect to reasonable meal management for 'optimal nutrition of family'. In addition, the government should try to make the various welfare policies to improve nutritional status of low income famines including the poor industrial complex-families.

Comparative study of the prenatal care among Seoul ana Chun Chon areas′clinics (일부 대.중도시의 임신부 병원진찰실태에 관한 비교연구)

  • 강정희
    • Journal of Korean Academy of Nursing
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    • v.4 no.2
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    • pp.121-130
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    • 1974
  • This study was performed with, two groups of 369 pregnant women, which consisted of the first group of 186 pregnant women taking physical examinations for birth at the Korea clinic in Seoul during the months of November and December in 1972, and the second group of 183 pregnant women taking physical examinations for birth at the Kang Won Provincial Hospital for the 12 months from October, 1972 to September 1973, as the results of this study the following concussion was obtained. 1. Age distribution indicated that the group of 25 through 34 age among them fallen 76 percent. 2. The time of the first physical examination by the 76% pregnant women of the second group at Chun Chon was in the initial period of pregnancy, but the time of that by every 33% pregnant women of the first group in Seoul came to the initial, middle and late period of pregnancy, evenly. 3. The 65.6% of the second group had one or two times of physical examination and the 80% of the first group had one to eight times of physical examination. 4. The mean pregnancy times was 1.9 to the first group and 2.8 to the second group, showing high pregnancy rate in Seoul city- 5. The 57.3% of the first group and the 31.3% of the second group did one times of abortion. The 3.2% of the first group and the 10.7% of the second group did more then six times of abortion, this meant big difference between two groups. The 24.1% of the first group had four times of pregnancy and the 18.1% of the second group had three or four times of it. These percentages was the highest of all. 6. Death rate during the period of pregnancy was shown to be 3.2% to the first group and 9.7% to the second group, consequently indicating gre311y high death rate in local city. 7. Many of the first group have three children and some of the second group have seven children. 8. As to totemics of pregnancy, 23.7% of the first group, and 49.7% of the second group were shown to have totemics of pregnancy, consequently with greatly high totemics rate of pregnancy in local city. The 4.0% of the first group and 37.0% of the second group was short of hemoglobin, with remarkable difference between the two groups.

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The estimation of the marine terrace of the Last Interglacial culmination stage(MIS 5e) in the Sanhari of Ulsan coast,southeastern Korea (울산 해안의 최종간빙기 최온난기 추정 해성단구)

  • Choi, Seong-Gil
    • Journal of The Geomorphological Association of Korea
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    • v.23 no.2
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    • pp.47-59
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    • 2016
  • The formation age and depositional environment of the marine terrace I of the estimated paleoshoreline altitude of 18m in Sanhari of Ulsan coast, southeastern Korea were investigated on the basis of examination of lithofacies and stratigraphy of terrace deposits. Marine deposits of the terrace is composed of rounded boulders(70cm in diameter) and rounded pebbles(1.0cm in diameter) which overlay them. The above rounded boulders which lie on the paleo-shore platform are considered to have been formed by wave abrasion in the same period that the paleo-shore platform was developed. The rounded pebbles which lie on the rounded boulder layer are considered to have been deposited in gravel beach and berm environment, judging from the laminae developed in this layer. The paleo-shore platform and marine rounded gravel layer of the terrace are assumed to have been formed in the large transgression period of the Last Interglacial culmination stage(MIS 5e), judging from the comparision of the formation age of 125ka B.P. of Juckcheon terrace I in the adjacent Pohang coast which was dated by amino acid dating. The terrestrial deposit of this terrace was largely composed of angular and subangular gravel mixed with marine rounded pebble which has been carried away mainly from the deposit of previous marine terraces and redeposited in this terrace. The lowest peat layer of terrastrial deposit was considered to have been deposited during the period from the late MIS 5e which is the estimated finishing time of deposition of the above marine gravels to the early stage of following regression period(MIS 5d) in which the sea level was still high. The sediments of angular and subangular gravel deposit which lie on this peat layer were assumed to have been deposited during the period from the early stage of the first regression period(MIS 5d) of the Last Interglacial to the Last Glacial. The lower part of the angular gravel layer is composed of the deposits of the fluvial and colluvial sediments, whereas most of the upper and middle part of the layer is mainly composed of angular gravels of colluvial sediments formed in the cold environment.

Paleomagnetism, Stratigraphy and Geologic Structure of the Tertiary Pohang and Changgi Basins; K-Ar Ages for the Volcanic Rocks (포항(浦項) 및 장기분지(盆地)에 대한 고지자기(古地磁氣), 층서(層序) 및 구조연구(構造硏究); 화산암류(火山岩類)의 K-Ar 연대(年代))

  • Lee, Hyun Koo;Moon, Hi-Soo;Min, Kyung Duck;Kim, In-Soo;Yun, Hyesu;Itaya, Tetsumaru
    • Economic and Environmental Geology
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    • v.25 no.3
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    • pp.337-349
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    • 1992
  • The Tertiary basins in Korea have widely been studied by numerous researchers producing individual results in sedimentology, paleontology, stratigraphy, volcanic petrology and structural geology, but interdisciplinary studies, inter-basin analysis and basin-forming process have not been carried out yet. Major work of this study is to elucidate evidences obtained from different parts of a basin as well as different Tertiary basins (Pohang, Changgi, Eoil, Haseo and Ulsan basins) in order to build up the correlation between the basins, and an overall picture of the basin architecture and evolution in Korea. According to the paleontologic evidences the geologic age of the Pohang marine basin is dated to be late Lower Miocence to Middle Miocene, whereas other non-marine basins are older as being either Early Miocene or Oligocene(Lee, 1975, 1978: Bong, 1984: Chun, 1982: Choi et al., 1984: Yun et al., 1990: Yoon, 1982). However, detailed ages of the Tertiary sediments, and their correlations in a basin and between basins are still controversial, since the basins are separated from each other, sedimentary sequence is disturbed and intruded by voncanic rocks, and non-marine sediments are not fossiliferous to be correlated. Therefore, in this work radiometric, magnetostratigraphic, and biostratigraphic data was integrated for the refinement of chronostratigraphy and synopsis of stratigraphy of Tertiary basins of Korea. A total of 21 samples including 10 basaltic, 2 porphyritic, and 9 andesitic rocks from 4 basins were collected for the K-Ar dating of whole rock method. The obtained age can be grouped as follows: $14.8{\pm}0.4{\sim}15.2{\pm}0.4Ma$, $19.9{\pm}0.5{\sim}22.1{\pm}0.7Ma$, $18.0{\pm}1.1{\sim}20.4+0.5Ma$, and $14.6{\pm}0.7{\sim}21.1{\pm}0.5Ma$. Stratigraphically they mostly fall into the range of Lower Miocene to Mid Miocene. The oldest volcanic rock recorded is a basalt (911213-6) with the age of $22.05{\pm}0.67Ma$ near Sangjeong-ri in the Changgi (or Janggi) basin and presumed to be formed in the Early Miocene, when Changgi Conglomerate began to deposit. The youngest one (911214-9) is a basalt of $14.64{\pm}0.66Ma$ in the Haseo basin. This means the intrusive and extrusive rocks are not a product of sudden voncanic activity of short duration as previously accepted but of successive processes lasting relatively long period of 8 or 9 Ma. The radiometric age of the volcanic rocks is not randomly distributed but varies systematically with basins and localities. It becomes generlly younger to the south, namely from the Changgi basin to the Haseo basin. The rocks in the Changgi basin are dated to be from $19.92{\pm}0.47$ to $22.05{\pm}0.67Ma$. With exception of only one locality in the Geumgwangdong they all formed before 20 Ma B.P. The Eoil basalt by Tateiwa in the Eoil basin are dated to be from $20.44{\pm}0.47$ to $18.35{\pm}0.62Ma$ and they are younger than those in the Changgi basin by 2~4 Ma. Specifically, basaltic rocks in the sedimentary and voncanic sequences of the Eoil basin can be well compared to the sequence of associated sedimentary rocks. Generally they become younger to the stratigraphically upper part. Among the basin, the Haseo basin is characterized by the youngest volcanic rocks. The basalt (911214-7) which crops out in Jeongja-ri, Gangdong-myon, Ulsan-gun is $16.22{\pm}0.75Ma$ and the other one (911214-9) in coastal area, Jujon-dong, Ulsan is $14.64{\pm}0.66Ma$ old. The radiometric data are positively collaborated with the results of paleomagnetic study, pull-apart basin model and East Sea spreading theory. Especially, the successively changing age of Eoil basalts are in accordance with successively changing degree of rotation. In detail, following results are discussed. Firstly, the porphyritic rocks previously known as Cretaceous basement (911213-2, 911214-1) show the age of $43.73{\pm}1.05$$49.58{\pm}1.13Ma$(Eocene) confirms the results of Jin et al. (1988). This means sequential volcanic activity from Cretaceous up to Lower Tertiary. Secondly, intrusive andesitic rocks in the Pohang basin, which are dated to be $21.8{\pm}2.8Ma$ (Jin et al., 1988) are found out to be 15 Ma old in coincindence with the age of host strata of 16.5 Ma. Thirdly, The Quaternary basalt (911213-5 and 911213-6) of Tateiwa(1924) is not homogeneous regarding formation age and petrological characteristics. The basalt in the Changgi basin show the age of $19.92{\pm}0.47$ and $22.05{\pm}0.67$ (Miocene). The basalt (911213-8) in Sangjond-ri, which intruded Nultaeri Trachytic Tuff is dated to be $20.55{\pm}0.50Ma$, which means Changgi Group is older than this age. The Yeonil Basalt, which Tateiwa described as Quaternary one shows different age ranging from Lower Miocene to Upper Miocene(cf. Jin et al., 1988: sample no. 93-33: $10.20{\pm}0.30Ma$). Therefore, the Yeonil Quarterary basalt should be revised and divided into different geologic epochs. Fourthly, Yeonil basalt of Tateiwa (1926) in the Eoil basin is correlated to the Yeonil basalt in the Changgi basin. Yoon (1989) intergrated both basalts as Eoil basaltic andesitic volcanic rocks or Eoil basalt (Yoon et al., 1991), and placed uppermost unit of the Changgi Group. As mentioned above the so-called Quarternary basalt in the Eoil basin are not extruded or intruaed simultaneously, but differentiatedly (14 Ma~25 Ma) so that they can not be classified as one unit. Fifthly, the Yongdong-ri formation of the Pomgogri Group is intruded by the Eoil basalt (911214-3) of 18.35~0.62 Ma age. Therefore, the deposition of the Pomgogri Group is completed before this age. Referring petrological characteristics, occurences, paleomagnetic data, and relationship to other Eoil basalts, it is most provable that this basalt is younger than two others. That means the Pomgogri Group is underlain by the Changgi Group. Sixthly, mineral composition of the basalts and andesitic rocks from the 4 basins show different ground mass and phenocryst. In volcanic rocks in the Pohang basin, phenocrysts are pyroxene and a small amount of biotite. Those of the Changgi basin is predominant by Labradorite, in the Eoil by bytownite-anorthite and a small amount pyroxene.

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Basin Evolution of the Taebaeksan Basin during the Early Paleozoic (전기 고생대 태백산분지의 분지 진화)

  • Kwon, Yi Kyun;Kwon, Yoo Jin;Yeo, Jung Min;Lee, Chang Yoon
    • Economic and Environmental Geology
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    • v.52 no.5
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    • pp.427-448
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    • 2019
  • This study reconstructed the paleoenvironments and paleogeography of the Taebaeksan Basin, through a review of the previous researches on sedimentology, paleontology and stratigraphy. This study also carried out a sequence stratigraphic analysis on regional tectonism and sea-level fluctuations on the basin during the Early Paleozoic. The basin broadly occur in the Taebaek, Yeongweol-Jecheon, Jeongseon-Pyeongchang, and Mungyeong areas, Gangwon province, South Korea. The basin-fills are composed mainly of mixed carbonates and siliciclastics, divided into the Taebaek, Yeongweol, Yongtan, Pyeongchang and Mungyeong groups according to lithologies and stratigraphic characteristics. Recently, there are a lot of studies on the provenance and depositional ages of the siliciclastic sequences of the basin. The detrital sediments of the basin would be derived from two separated provenances of the core-Gondwana and Sino-Korean cratons. In the Early Cambrian, the Taebaek and Jeongseon-Pyeongchang platforms have most likely received detrital sediments from the provenance of the Sino-Korean craton. On the other hand, the detrital sediments of the Yeongweol-Jecheon platform was probably sourced by those of the core-Gondwana craton. This separation of provenance can be interpreted as the result of the paleogeographic and paleotopographic separation of the Yeongweol-Jecheon platform from the Taebaek and Jeongseon-Pyeongchang platforms. The analyses on detrital zircons additionally reveal that the separation of provenance was ceased by the eustatic rise of sea-level during the Middle Cambrian, and the detrital sediments of the Taebaeksan Basin were entirely supplied from those of the core-Gondwana craton. During that period, sediment supply from the Sino-Korean craton would be restricted due to inundation of the provenance area of the craton. On the other hand, the Jeongseon-Pyeongchang platform sequences show the unconformable relationship between the Early Cambrian siliciclastic and the Early Ordovician carbonate strata. It is indicative of presence of regional uplift movements around the platform which would be to the extent offset of the effects of the Middle to Late Cambrian eustatic sealevel rise. These movements expanded and were reinforced across the basin in the latest Cambrian and earliest Ordovician. After the earliest Ordovician, the basin was tectonically stabilized, and the shallow marine carbonate environments were developed on the whole-platform by the Early Ordovician global eustatic sea-level rise, forming very thick carbonate strata in the basin. In the Late Ordovician, the Early Paleozoic sedimentation on the basin was terminated by the large-scale tectonic uplift across the Sino-Korean platform including the Taebaeksan Basin.

Yeomjae Song Tae-hoe Origin and art world of calligraphy and painting (염재(念齋) 송태회(宋太會) 서화의 연원과 예술세계)

  • Kim Doyoung
    • The Journal of the Convergence on Culture Technology
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    • v.9 no.5
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    • pp.255-262
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    • 2023
  • In the early 20th century, Yeomjae Song Tae-hoe (念齋 宋泰會, 1872-1941), a disciple and onetime adopted son of teacher Song Su-myeon(宋修勉, 1847-1916), moved to Gochang and laid the foundation for Gochang calligraphy and painting, and it can be seen that a full-fledged flow began. Yeomjae Song Tae-hoe was a scholar and calligrapher of the late Joseon Dynasty and modern period from Hwasun, Jeollanam-do. He is a person who created the foundation of Gochang calligraphy and painting while working as an educator in Chinese literature, calligraphy, and painting, mainly in his hometown of Hwasun and Gochang, while engaging in creative activities. He was intelligent from a young age and showed an extraordinary talent for calligraphy. At the age of 16, he passed the Jinsa exam (童蒙進士) and became the youngest student to study at Sungkyunkwan. He was active by holding exhibitions nationwide based in Gochang and Jeonju, and was also an educator who fostered younger students by establishing Gochang High School (currently, Gochang Middle and High School) to cultivate national spirit and history. Yeomjae drew strong and healthy landscape paintings under the absolute influence of the painting style of Saho Song Su-myeon, and dealt with various materials of southern school literati paintings such as flowers and birds and four plants. In particular, he is a representative calligrapher who encompasses the early modern era and the modern era in that he expressed his interest in new cultural artifacts as well as the realization of a modern-oriented realistic landscape based on Korean natural beauty. He laid the foundation for modern and contemporary calligraphy and painting. Goam Lee Eung-no (顧菴 李應魯, 1904-1989), a world-renowned painter, learned the basics of ink painting from Yeomjae in his late teens.However, compared to his various artistic and social activities, it is regrettable that he is limited and evaluated as a local writer.

Stratigraphy and Provenance of Non-marine Sediments in the Tertiary Cheju Basin (제주분지 제삼기 육성층의 층서 및 퇴적물 기원)

  • Kwon Young-In;Park Kwan-Soon;Yu Kang-Min;Son Jin-Dam
    • The Korean Journal of Petroleum Geology
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    • v.3 no.1 s.4
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    • pp.1-15
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    • 1995
  • Seismic reflection profiles and exploratory drilling well samples from the southern marginal-continental shelf basin of Korea delineate that the Tertiary sedimentary sequences can be grouped into five sequences (Sequence A, Sequence B, Sequence C, Sequence D and Sequence E, in descending order). Paleontologic data, K-Ar age datings, correlation with tuff layers and sequence stratigraphic analysis reveal that the sequences A, B, C, D and E can be considered as the deposits of Holocene $\~$ Pleistocene, Pliocene, Late Miocene, Early $\~$ Middle Miocene and Oligocene, respectively. The sequence stratigraphic and structural analyses suggest that the southern part of the Cheju Basin had experienced severe folding and faulting. NE-SW trending strike-slip movement is responsible for the deformation. The sinistral movement of strike-slip fault ceased before the deposition of Sequence B. Age dating and rare-earth elements analysis of volvanic rocks reveal+ that the Sequence D was deposited during the Early $\~$ Middle Miocene and the Sequence I was deposited earlier than the deposition of the Green Tuff Formation. Sedimentary petrological studies indicate that sediments of the Sequence I came from the continental block provenance. After the deposition of the Sequence E, uplift of the source area resulted in increase of sediment supply, subsidence and volcanic activities. The Sequence D show these factors and the sediments of the Sequence D are considered to be transported from the recycled orogenic belt.

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Meteorological Condition and Pest Management (기상환경과 병해충 발생 및 그 대책)

  • 현재선
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.27 no.4
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    • pp.361-370
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    • 1982
  • The effects of climatic factors on organisms lire variable and complex, and it, however, can be interpreted in terms of those on the distribution and those on the population densities. The distribution of an organism may largely be determined by the temperatures, except some temporal organisms which are depended on the air mass movements. Population density of an organism is determined by various climatic factors, such as previous winter temperature, temperature of growing season and rainfall. The start of growing season of the rice plants has been shifted to earlier since last decade in Korea. This may mean that the overall climatic condition during the growing season might be considerably different from those in past years, and such a difference in climatic conditions might have close relation with the recent status of the diseases and insect pests through direct effects on the physiology and population dynamics of the organisms, as well as through on the biotic associations of the pest organisms. The white back planthopper and brown planthopper have become the key insect pests in Korea in recent years. They are migratory and have high reproductive pontentials and more generations than average residential insects. The synchronization of the migrants and physiological condition of the rice plants seems to be the important factors in relation to the recent outbreaks of these insects; the high reproductive rate can be obtained with the growth stage of rice being 30-50 days after transplanting. The modication of the microclimate associated with high plant density and some other introduced new cultural techniques also have some relation with the outbreak. The key diseases of the rice are the blast disease, sheath blight and the bacterial leaf blight. For the rice blast, the seedling blast and leaf blast during the early growing season and the neck blast, have become more serious, the former may be related to hotbed nursery and the later may be related to the high humidity in early August, and synchronization of the heading time which has been shifted to early part from middle or late part of August. In general, for the rice diseases, the development of the new races have been the most serious which are largely resulted from the introduction of the new varieties, but it also seems to be related with the prolonged periods of the favorable condition associated with the shifted growing seasons. In general, the diseases and insect pest problems have become much more variable and complex, and control measures should be based on the thorough knowledge of the ecology of the pest organisms, that is, effects of various environmental factors on the disease cycle; spore release, spore deposition, infection, colonization and sporulation of the disease organisms, and those on the development, reproductive potentials, dispersal, age specific responses of the insects. The well organized real-time pest management systems, such as alfalfa weevil management system developed at the Purdue University in U.S., is the prime importance for the implementation of the pest management principles.

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