• Journal of the Korean earth science society
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• v.43 no.3
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• pp.405-429
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• 2022

Detrital zircon LA-MC-ICP-MS U-Pb dating of the Cretaceous Gurye Group, Gurye Basin, was carried out. Gurye Group consists of Supyeongri, Geumjeongri, Togeum, and Obongsan formations in ascending order, and five samples were collected for age dating. Based on the dating results, the lowermost Supyeongri and the uppermost Obongsan formations show narrow age ranges. Only Precambrian and Late Cretaceous zircons were found in the Supyeongri and Obongsan formations, respectively. However, the upper and lower Geumjeongri, and Togeum formations show wide age ranges from the Precambrian to Cretaceous. The youngest detrital zircon U-Pb ages of each formation except the Supyeongri Formation, which lacks Cretaceous zircon, were calculated to be ca. 107.4 Ma in the lower Geumjeongri Formation, ca. 104.6 Ma in the upper Geumjeongri Formation, ca. 97.7 Ma in the Togeum Formation, and ca. 88.5 Ma in the Obongsan Formation. Such results indicate that the depositional age of the Gurye Group can be constrained from the Lower Cretaceous Albian to the Upper Cretaceous Coniacian. Based on the distribution of the detrital zircon ages from each formation, the source area of the Gurye Group is interpreted to have been extended from the adjacent Youngnam Massif to the Okcheon Belt throughout the basin evolution. The increase of the Cretaceous zircon with time is thought to reflect the slab roll-back of the proto-Pacific plate during the Cretaceous.

• Informatization Policy
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• v.18 no.3
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• pp.69-87
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• 2011

North Korea has been striving to promote a national informatization strategy after getting through the period of 'Arduous March'in the 1990s. First of all, North Korea has made organizations required for implementing the national informatization strategy. They reorganized and created the Science & Education Ministry, the Machine & Industry Ministry, and the 21 bureau under the Workers' Party of Korea while making special units in the Royal Mail, Royal electron & industry, National Academy of Sciences under cabinet. Then they completed all the essential organizational system for informatization including newly built specialized agencies: 'Korea Computer Center; KCC' & 'Pyongyang Informatics Center: PIC'. But North Korea's informatization system has a rigid hierarchy. All the organizations in the hierarchical system are controlled by the Workers' Party of Korea. It means that North Korea consider IT as a tool for the centralized control of the Party and the government. So, these characteristics of North Korea's informatization system clearly give us a picture that tells us what they want from the national informatization and where they're going.

• Korean Journal of Remote Sensing
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• v.14 no.1
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• pp.1-16
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• 1998

Microwave brightness temperature data measured from the Special Sensor Microwave/Imager (SSM/I) aboard Defense Meteorological Satellite Program (DMSP) satellite are used to investigate the characteristics of hydrological features of the East Asian summer monsoon during 1994 and 1995. The analyzed parameters include total columnar water vapor, cloud liquid water, and rain rate. These are estimated from SSM/I brightness temperature data for the two summer seasons (June, July, August) of 1994 and 1995 over the Asian monsoon region (0$^{\circ}$-60$^{\circ}$N, 45$^{\circ}$-180$^{\circ}$E). Results indicate that there are periodic westward movement of dry air over the 20$^{\circ}$-30$^{\circ}$N latitudinal belt with about 20-30 day period. Considering that the location of the North Pacific high is closely linked to the evolution of the monsoon activities over East Asia, the westward expansion of the North Pacific high may be the one important element modulating the monsoon intensity.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.105-110
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• 2018

The North Korea nuclear issue is now posing a serious security threat to the Korea and Northeast Asia. Accordingly, the South Korean military is pushing for the introduction of long-range air-to-surface flights and the development of domestic nuclear facilities that can precisely hit North Korea headquarters building and nuclear facility even hundreds of kilometers above the border. In this paper, we removed the cable braid for securing the weight of the missile among several design elements for long-range air-to-surface missile development and estimated and analyzed the resulting performance. The possibility of braid removal was analyzed in terms of crosstalk inside the cable and CS114, RE101 of MIL-STD-461F.

• Journal of the Korean association of regional geographers
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• v.17 no.2
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• pp.150-166
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• 2011

This study aims to investigate the differences of synoptic characteristics and frontal structures over East Asia according to the main path types of water vapor flux (WVF) of 850hPa surface in cases of the heavy rainfall in the south coastal region of Korea during the Changma season (June and July), In the cases of type A in which the main path of WVF is running from the South china Sea via the South china to the South Sea of Korea, the North Pacific subtropical anticyclone (NPSA) expands to the South China and strong cyclones appear in the Yellow Sea. In cases of type B and C in those the main paths of WVF are running from the South China Sea via the Western Pacific Ocean near Taiwan to the South Sea and from the Western North Pacific Ocean to the South Sea respectively, tropical cyclones appear frequently near Taiwan and the NPSA shifts northward. In the case of type D in which the main path of WVF appear only near the South Sea, strong cyclones appear near the Yellow Sea. In all cases upper jets are intensified in the northern part of the heavy rainfall region and low-level jets appear near the main paths of WVF. In the view of frontal structure, deep active-type of the Changma front is identified in most cases of all types. In this point the Changma season is different from the Baiu season in Western Japan where many cases of shallow active-type of the Baiu front appear.

• Journal of the Korean association of regional geographers
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• v.6 no.2
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• pp.57-69
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• 2000

The purpose of this study is to identify distributional characteristics of autumn droughts in occurrence frequency and to analyze synoptic characteristics on the surface pressure fields and 500hPa levels for autumn droughts in Korea. The regional distributions of autumn droughts in occurrence frequency vary according to the monthly regional distributions of the precipitation variabilities in Korea. In september, the southwestern and the mid western parts of Korean Peninsula have high rate of drought frequency, while the eastern coast regions have low rate of it. It means that the regional distribution of the drought frequency in september indicates west-high and east-low pattern. In October, the regional distribution of the drought frequency shows low variations on regions, but in November the inland areas have low rate of drought frequency, whereas the coastal areas have high rate of it. Negative anomalies appear on the surface and 500hPa level, around Korean Peninsula during the drought period of early autumn. Positive height anomalies areas are extended from the Sea of Okhotsk to the central part of the North Pacific Ocean. It indicates that the occurrence frequencies of blocking high and ridge are high around the Sea of Okhotsk. When the pressure system, such as migratory anticyclone, stays around the Korean Peninsula, a drought occurs. In late autumn drought, the positive anomalies appear in the west and the negative anomalies in the east are generated, respectively and therefore, zonal wind is strong around Korean Peninsula. In consequence, occurrences of droughts in early autumn have a different mechanism from those of late autumn.

• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.85-94
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• 2008

This study is to construe spatio-temporal characteristics of temperature in cities and changes of climatical regions in analyzing a change of Korea Peninsular climate. We used daily mean air temperature data which was collected in South and North Korea for the past 34 years from 1974 to 2007. We created temperature map of 500m resolution using Inverse Distance Weight in application with adiabatic lapse rate per month in linear relation with height and temperature. In the urbanization area, the data analyzed population in comparison with temperature changes by the year. An annual rising rate of temperature was calculated $0.0056^{\circ}C$, and the temperature was increased $2.14^{\circ}C$ from 1974 to 2107. The south climate region in Korea by the Warmth index was expanded to the middle climate region by the latitude after 1990s. A rise of urban area in mean temperature was $0.5-1.2^{\circ}C$, Seoul, metropolitan and cities which were high density of urbanization and industrialization with the population increase between 1980s and 1990s. In case of North Korea, Cities were Pyeongyang, Anju, Gaecheon, Hesan. A rise in cities areas in mean temperature has influence on vegetation, especially secondary growth such as winter buds of pine trees appears built-up area and outskirts in late Autumn. Finally, nowaday we confront diverse natural events over climatical changes, We need a long-term research to survey and analyze an index on the climatical changes to present a systematic approach and solution in the future.

• Journal of the Korean earth science society
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• v.34 no.4
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• pp.313-328
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• 2013

Jurassic granitoids in the northeastern part of the Yeongnam Massif are possibly the result of intensive magmatic activities that occurred in response to subduction of the proto-Pacific plate beneath the northeast portion of the Eurasian plate. Geochemical studies on the granitic rocks are carried out in order to constrain the petrogenesis of the granitic magma and to establish the paleotectonic environment of the area. Whole rock chemical data of the Uljin granitoids in the northeastern part of the Yeongnam Massif indicate that all of the rocks have the characteristics of calcalkaline series in subalkaline field. The overall major element trends show systematic variations in each granitic body, but the source materials of each granitoids seem to have different chemical composition. The Uljin granitoids are different from other granitic rocks, which distributed vicinity of the study area, in the contents of $Al_2O_3$ and trace elements such as Cr, Co, Ni, Sr, Y and Nb. The Uljin granitoids have geochemical features similar to slab-derived adakites such as high $Al_2O_3$, Sr contents and high Sr/Y, La/Yb ratios, but they have low Y and Yb contents. The major ($SiO_2$, $Al_2O_3$, MgO) and trace element (Sr, Y, La, Yb) contents of the Uljin granitoids fall well within the adakitic field. The Uljin granitoids have similar geochemical characteristics, paleotectonic environments and intrusion ages to those of the Yatsuo plutonic rocks of Hida belt located on northwestern part of Japan. Chondrite normalized REE patterns show generally enriched LREEs ($(La/Yb)_{CN}=10.6-103.4$) and are slight negative to flat Eu anomalies. On the ANK vs. A/CNK and tectonic discrimination diagrams, parental magma type of the granites corresponds to I-type and volcanic arc granite (VAG). Interpretations of the chemical characteristics of the granitic rocks favor their emplacement in a compressional tectonic regime at the continental margin during the subduction of Izanagi plate in Jurassic period.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.4
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• pp.282-293
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• 2018

The heading response of rice varieties is determined by the combined effects of their basic vegetative phase (BVP), photoperiod-sensitivity (PS), and thermo-sensitivity (TS). This study was performed to analyze the effect of differences among heading ecotypes of rice on their heading response in the field. To do this, we investigated the heading response of 15 varieties grown under different day-length and temperature conditions in a phytotron. The characteristics of heading ecotypes were compared to the heading responses in the field-grown rice varieties that were used in the phytotron experiments. The ranges of these characteristics across the 15 varieties were 18 - 35 days for BVP, 12 - 61 days for PS, and 12 - 35 days for TS. In comparisons of coupled varieties that differed only in a single trait among BVP, PS, and TS, the variety with the longer BVP and that with the higher PS had a longer period from sowing to heading (DTH), while the variety with the higher TS had a shorter DTH. The comparative magnitude of DTH in the coupled varieties followed the PS trait when BVP and PS were involved, the BVP trait when BVP and TS were involved, and the PS trait when PS and TS were involved in the heading response of field-grown rice. When comparing the coupled varieties with different traits of the three examined factors, the heading response was consistent with the PS trait. The DTH in all 15 varieties was significantly correlated with the PS, and the DTH in 9 selected varieties with a relatively small PS was correlated with BVP. The reduced DTH of rice in the July 10 seeding treatment compared to those in the June 25 and May 11 seeding treatments was positively associated with PS, but not with TS. We concluded that the heading response of rice varieties under natural conditions in Korea is mainly governed by the PS trait and is also greatly affected by the BVP trait when the PS is small.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.178-189
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• 2008

The distribution of inorganic nutrients and their remineralization ratio in the divergence zone ($7^{\circ}{\sim}10.5^{\circ}N$) of the northeastern Pacific were investigated from July 2003 to July 2007. A divergence zone along the boundary of the North Equatorial Counter Current (NECC) and North Equatorial Current (NEC) at $10^{\circ}N$ was observed in July 2007 when the La Nina event and divergence-related upwelling was strong. The mean depth of oligotrophic surface mixed layer in the divergence zone was 46, 61, and 30 m in July 2003, August 2005, and July 2007, respectively. Below the surface mixed layer, a nutricline was clearly observed. The depth integrated value of nitrate including nitrite (DIVn) in the upper layer($0{\sim}100$ m depth) ranged from 5.51 to 21.71 $gN/m^2$(mean 12.82 $gN/m^2$) in July 2003, from 5.62 to 8.46 $gN/m^2$ (mean 7.15 $gN/m^2$) in August 2005, and from 8.98 to 27.80 $gN/m^2$(mean 21.12 $gN/m^2$) in July 2007. The maximum DIVn was observed at the divergence zone. The distributions of phosphate(DIVp) and silicate(DIVsi) were similar to that of DIVn and the DIVn/DIVsi ratio was $0.87{\pm}0.11$ in the upper layer. The limiting nutrient for phytoplankton growth in the study area was identified as nitrogen(N/P ratio=14.6). The nitrate (including nitrite) concentrations were lower in the region mainly affected by NEC than in the region affected by NECC. The study area of low silicate concentrations was also considered to be Si-limiting environment. The remineralization ratios of nutrients were $P/N/-O_2=1/14.6{\pm}1.1/100.4{\pm}8.8(23.44{\leq}Sigma-{\theta}{\leq}26.38)$ in the study area. These ratios suggested remineralization process in the surface layer of divergence zone.