• Economic and Environmental Geology
• /
• v.33 no.4
• /
• pp.249-260
• /
• 2000

The development of dual volcanic chains, parallel to the trend of the subduction trench, is observed in the southern part of Korea. Elsewhere on the Earth volcanic arcs dominantly consist of two such chains. In the southern part of Korea, two volcanic chains within a single volcanic arc was developed. Kyongsang basin, where the first volcanic chain located, and Youngdong-Kwangju depression zone where the second volcanic zone located, showed sub-parallel volcanic rock distributed areas. Concentrations of incompatible elements in the southern part of Korea samples show clear across-arc variations, with lavas from the first volcanic chain being most depleted in these elements, all incompatible element concentrations increase towards the second volcanic chain. The above across-arc variation may be caused by the difference in solid phases coexisting with the fluid phases during the dehydration processes. The concentrations of incompatible elements, Zr/Y ratios, and Rb/K ratios indicate that the second volcanic chain (Youngdong-Kwangiu depression zone) was generated by low degrees of partial melting at the deeper depth compared to the conditions of the first volcanic chain (Kyongsang basin) and residual garnet probably attributed to the their partial melting.

• Korean journal of communication and information
• /
• v.57
• /
• pp.160-180
• /
• 2012

This research points out how the major newspapers and the Local newspaper try to report the issue of development in Incheon Free Economic Zone differently and observe how the press has played a role in a process. It is seen that the type of story-leading has been followed by properly traditional one as usual and reflected the recent trends well in both. The perspectives of ChosunIlbo to look at the regional issue is taken in the situation of a middle clear attitude but KyeonginIlbo is faithful to make the position of the monitor. In other words, a Metropolitan newspaper often deals with the regional issues in a more passive posture, while a Local daily newspaper tries to report the same issue in a more positive and active form. This kind of attitude upon news composition reflects the quality of the news, which is a standard of actual newspaper articles. The ChosunIlbo focuses on the political issues more while, KyeonginIlbo emphasizes on the cultural similarities. And they trace the economic importance, human interest but less to the structural figures.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.1B
• /
• pp.8-15
• /
• 2008

Cognitive radio technology enables to share the spectrum dedicated to primary users. In CR network, it is of primary concern to protect the primary users. Thus, it is required to periodically sense the spectrums occupied by primary users and adapt the communication parameters used by CR users to protect the primary users. However, it is inevitable to experience the hidden node problem due to the primary users, that are not detected by spectrum sensing. To perfectly protect the primary users, it is essential to address the hidden node problem in CR network. In this paper, we propose a new approach to handle the hidden node problem and evaluate the performance of proposed scheme.

• Journal of the Korean Geophysical Society
• /
• v.4 no.1
• /
• pp.11-20
• /
• 2001

Seismic refraction and electrical resistivity surveys were conducted in Bangeosan Maaebul site located in Haman, Kyungnam, in order to present geophysical safety analysis method for masonry cultural properties. Seismic refraction exploration revealed that the ground was composed of three layers in term of seismic wave velocity; the upper, medium, and lower layers. The low velocity ranging from 308 to 366 m/sec in upper layer suggests weathered soil, the intermediate velocity from 1906 to 2090 m/sec in the medium layer indicates weathered rocks, and the high velocity from 5061 to 5650 m/sec in the lower layer implies extremely hard rocks. Our seismic result suggests that the upper and medium layer around the Maaebul should be reinforced to support the construct. The result of electric resistivity survey shows that there exists a low resistivity zone, ranging from 131 to 226 Ohm-m, at the right side of the Maaebul with the direction of NE-NNE. This area is the weakness zone as it plays role of the underground water passage in rainy season.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.29 no.1
• /
• pp.42-55
• /
• 2024

To discover unrecorded diatoms, seawater, sand, and pebbles were collected from the intertidal zone of five tidal flats from 2016 to 2023. Diatoms were isolated from the collected samples, cultured, and the ultrastructure of the cells was observed using a scanning electron microscope. 7 species of unrecorded diatoms, consisting of 3 orders, 5 families, and 7 genera, were discovered: Gomphoseptatum aestuarii, Rhoiconeis pagoensis, Seminavis exigua, Plagiolemma distortum, Staurotropis seychellensis, Biremis sigmoidea, Liriogramma sarcophagus. Among these, four genera, Rhoiconeis, Plagiolemma, Staurotropis, and Liriogramma, are reported for the first time in Korea. L. sarcophagus was separated from the central diatom Asteromphalus and transferred to Liriogramma, but its phylogenetic position has not yet been clearly established.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.7 no.2
• /
• pp.60-67
• /
• 2002

To determine whether nitrogen (N) uptake by phytoplankton below the euphotic zone in the Yellow Sea is considerable, we measured the uptake rates of nitrate and ammonium using $^{15}N$-labeled stable isotope $K^{15}NO_{3}$ and $^{15}NH_{4}Cl$, in May and November 1997 at total 10 stations. Depth-integrated uptake rates of nitrate and ammonium over the euphotic zone during this study ranged from 1.8 to 15.3 mg N $m^{-2}$ $d^{-1}$ and from 5.0 to 132.2 mg N $m^{-2}$ $d^{-1}$, respectively, and ammonium uptake predominated at 9 of 10 stations (1.9-19.4 fold). Depth-integrated uptake rates of nitrate and ammonium over the whole water column ranged from 2.9 to 22.0 mg N $m^{-2}$ $d^{-1}$ and from 15.7 to 175.5 mg N $m^{-2}$ $d^{-1}$, respectively. The significant proportion of whole water column N uptake was attributed to uptake by phytoplankton below the euphotic zone, ranging from 13.0 to 86.2% for nitrate and from 13.8 to 67.8% for ammonium, indicating that phytoplankton N uptake below the euphotic zone is at times considerable in the study area. The results suggest that when phytoplankton below the euphotic zone in the Yellow Sea are again entrained into the euphotic zone by a certain physical forcing such as turbulent mixing and the vertical movement of thermocline, these episodic events may significantly affect the material fluxes within the euphotic zone. Furthermore, the results suggest that a portion of regenerated production estimated from $^{15}N$-ammonium uptake should be included in new production estimates, which otherwise could be underestimated in the Yellow Sea.

• Journal of Korean Society of Forest Science
• /
• v.68 no.1
• /
• pp.32-36
• /
• 1985

Megagametophyte tissues of Pinus densiflora were subjected to study the inheritance of acid phosphatase (ACP), alcohol dehydrogenase (ADH) and catalase (CAT) isozymes by starch gel zone-electrophoresis. At least three or four zones were segregated for ACP isozyme. However, as one isozyme of ACP-A zone was separated clearly, only that isozyme was analysed. Five isozyme phenotypes (A1-A5), observed in ACP-A zone, were segregated to a simple Mendelian ratio, suggesting that these are controlled by five codominant alleles existed at ACP-A locus. Two zones of activity were segregated in the gels after staining for ADH, the more anodal zone (ADH-A) of the two was invariant in our materials. Three isozyme phenotypes (B1-B3) were observed in ADH-B zone and these variants showed a 1:1 segregation pattern, suggesting that each variant is controlled by three codominant alleles at ADH-B locus. A total of five isozyme phenotypes, composed of multiple bands, were observed in CAT isozyme. The segregation of these phenotypes in heterozygous trees did not show any significant deviation from a 1:1 segregation. Therefore, the genetic control of CAT isozyme in Pinus densiflora seeds seems to be based on a single locus (CAT-A) with Five codominant alleles ($A_1-A_5$).

• The Korean Journal of Pesticide Science
• /
• v.12 no.3
• /
• pp.236-242
• /
• 2008

Laboratory and greenhouse experiments were conducted to evaluate the effect of root zone application of some systemic insecticides for control of the brown planthopper (BPH), Nilaparvata lugens, as one of the management option to minimize the adverse effects and maximize the efficacy of insecticide application. Five systemic insecticides, namely, carbofuran, carbosulfan, diazinon, ethoprophos and imidacloprid, as granular formulation were placed in the root zone and measured the mortality, fecundity, and nymphal survivorship of the planthopper. Diazinon and ethoprophos did not show the significant mortality of the BPH. When the BPH were inoculated at the day of carbofuran treatment, adult mortality was shown almost 100% at seven days after treatment and BPH nymphs were remained very few on rice at 25 days after treatment. When carbofuran were placed 10 days before the BPH inoculation, it showed almost 100% adult mortality after one day, and no nymphs were found until 25 day after inoculation. Efficacy of carbofuran on BPH when applied in 10 day-old rice was higher than in 30 day-old rice. These results indicated that the root zone application of carbofuran can control N. lugens effectively with less adverse effect to the natural enemies inhabited on rice plants.

• Korean Journal of Ecology and Environment
• /
• v.38 no.1 s.110
• /
• pp.30-44
• /
• 2005

To investigate the flora and vegetation structure of vascular plants in the littoral zone of Paldang Reservoir, from April, 2003 to April 2004, nine sampling sites were selected. Along the Paldang Reservoir, 128 taxa, consisted of 51 families and 96 genera, were identified, among them, hydrophytes were confirmed as 38 taxa, which was comprised 29.7% to total taxa, whereas hygrophytes were 44 taxa and terrestrial plants were 46 taxa. Emergent hydrophytes consists of 21 taxa, including Phragmites australis and Typha angustifolia, and next, submerged hydrophytes were 8 taxa. However, the kinds and vegetation area of submerged hydorphytes were reduced compared to previous studies. In the littoral zone of Paldang Reservoir, the aquatic vegetation was widely developed near Dumulmori, Yangsuri, and Kwangdong Bridge, downstream of Kyungancheon. The average number of hydrophyte per sampling sites were 2.7 taxa, whereas hygrophytes were 2.5, and land plants were 1.8. In addition, the hydrophytes in the littoral zone of Paldang Reservoir showed the typical vertical zonation pattern like a natural swamp. These results mean that the littoral zone of Paldang Reservoir has the typical characteristics of aquatic plant ecosystem.

• The Journal of Engineering Geology
• /
• v.25 no.4
• /
• pp.485-498
• /
• 2015

Structural analysis for a large-scale fault in Maegok-dong, Ulsan, was carried out based on filed-works to investigate the geometric and kinematic characteristics of the fault as well as its Quaternary slip. As results, a series of repeated stratigraphy, minor faults, fracture zones, and deformation band clusters are observed over a distance of about 100 m in the first studied site consisting of sedimentary rocks, which may indicate the damage zone of a large-scale fault in this site. In the second site, mainly composed of granitic clastic rocks, a large-scale thrust fault is expected based on low-angle dipping faults showing branched and/or merged patterns. Age of the last slip on this fault was restrained as after 33,275 ± 355 yr BP based on radiocarbon dating for organic material included in the gouge zone. Dimension of fault damage zone, dominant sense of slip, and age of the slip event associated with the fault suggest that these structures have a close relationship with the Ulsan Fault and/or Yeonil Tectonic Line, which are well-known large-scale neotectonic structural features around the study area. Therefore, it is necessary to study the characteristics of the faults in detail based on structural geology and paleoseismology in order to ensure seismic and geologic stability of the buildings under construction, and to prevent geologic hazards in this area.