• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.22 no.1
• /
• pp.31-44
• /
• 2017

Pfiesteria piscicida is one of heterotrophic dinoflagellate having toxic metaboliges, and it is difficult to detect and quantify this dinoflagellate via light microscope due to small size and morphological similarity with Pfiesteria-like dinoflagellate (PLD) species. Alternatively, we developed quantitative real-time PCR assay based on EvaGreen and determined field accessibility throughout the investigation of distribution in the entire Korean coastal waters and population dynamics in Shihwa Lake. The P. piscicida-specific primers based on internal transcribed spacer 1 (ITS 1) were designed and the specificity of primers was confirmed by PCR with other genomic DNAs which have genetic similarity with target species. Through real-time PCR assay, a standard curve which had a significant linear correlation between log cell number and $C_T$ value ($r^2{\geq}0.999$) and one informative melting peak ($88^{\circ}C$) were obtained. These results implies that developed real-time PCR can accurately detect and quantify P. piscicida. Throughout the field applications of real-time PCR assay, P. piscicida was distributed in western (Mokpo and Kimje) and easthern (Gangneng) Korean coastal water even though light microscopy failed to identify P. piscicida. In the investigation of population dynamics in Shihwa Lake, the density of P. piscicida was peaked in June, July and August 2007 at St. 1 where salinity (${\leq}15psu$) was lower than the other 2 sites. In this study, we successed to develop EvaGreen bassed real-time PCR for detection and quantification of P. piscicida in fields, so this developed assay will be useful for various ecological studies in the future.

• Korean Journal of Remote Sensing
• /
• v.34 no.6_4
• /
• pp.1503-1517
• /
• 2018

Mt. Baekdu is a stratovolcano located at the border between China and North Korea and is known to have formed through its differentiation stage after the Oligocene epoch in the Cenozoic era. There has been a growing interest in the magma re-activity of Mt. Baekdu volcano since 2010. Several research projects have been conducted by government such as Korea Meteorological Administration and Korea Institute of Geoscience and Mineral Resources. Because, however, the Mt. Baekdu volcano is located far from South Korea, it is quite difficult to collect in-situ observations by terrestrial equipment. Remote sensing is a science to analyze and interpret information without direct physical contact with a target object. Various types of platform such as automobile, unmanned aerial vehicle, aircraft and satellite can be used for carrying a payload. In the past several decades, numerous volcanic studies have been conducted by remotely sensed observations using wide spectrum of wavelength channels in electromagnetic waves. In particular, radar remote sensing has been widely used for volcano monitoring in that microwave channel can gather surface's information without less limitation like day and night or weather condition. Radar interferometric technique which utilized phase information of radar signal enables to estimate surface displacement such as volcano, earthquake, ground subsidence or glacial movement, etc. In 2018, long-term research project for collaborative observation for Mt. Baekdu volcano between Korea and China were selected by Korea government. A volcanic specialized research center has been established by the selected project. The purpose of this paper is to introduce about remote sensing techniques for volcano monitoring and to review selected studies with remote sensing techniques to monitor Mt. Baekdu volcano. The acquisition status of the archived observations of six synthetic aperture radar satellites which are in orbit now was investigated for application of radar interferometry to monitor Mt. Baekdu volcano. We will conduct a time-series analysis using collected synthetic aperture radar images.

• The Journal of the Petrological Society of Korea
• /
• v.28 no.3
• /
• pp.171-193
• /
• 2019

This study aims to identify the geometry and internal structures of the Yeongdeok Fault, a branch fault of the Yangsan Fault, by detailed mapping and to characterize its kinematics by analyzing the attitudes of sedimentary rocks adjacent to the fault, slip data on the fault surfaces, and anisotropy of magnetic susceptibility (AMS) of the fault gouges. The Yeongdeok Fault, which shows a total extension of 40 km on the digital elevation map, cuts the Triassic Yeongdeok Granite and the Cretaceous sedimentary and volcanic rocks with about 8.1 km of dextral strike-slip offset. The NNW- or N-S-striking Yeongdeok Fault runs as a single fault north of Hwacheon-ri, Yeongdeok-eup, but south of Hwacheon-ri it branches into two faults. The western one of these two faults shows a zigzag-shaped extension consisting of a series of NNE- to NE- and NNW-striking segments, while the eastern one is extended south-southeastward and then merged with the Yangsan Fault in Gangu-myeon, Yeongdeok-gun. The Yeongdeok Fault dips eastward with an angle of > $65^{\circ}$ at most outcrops and shows its fault cores and damage zones of 2~15 m and of up to 180 m wide, respectively. The fault cores derived from several different wall rocks, such as granites and sedimentary and volcanic rocks, show different deformation patterns. The fault cores derived from granites consist mainly of fault breccias with gouge zones less than 10 cm thick, in which shear deformation is concentrated. While the fault cores derived from sedimentary rocks consist of gouges and breccia zones, which anastomose and link up each other with greater widths than those derived from granites. The attitudes of sedimentary rocks adjacent to the fault become tilted at a high angle similar to that of the fault. The fault slip data and AMS of the fault gouges indicate two main events of the Yeongdeok Fault, (1) sinistral strike-slip under NW-SE compression and then (2) dextral strike-slip under NE-SW compression, and shows the overwhelming deformation feature recorded by the later dextral strike-slip. Comparing the deformation history and features of the Yeongdeok Fault in the study area with those of the Yangsan Fault of previous studies, it is interpreted that the two faults experienced the same sinistral and dextral strike-slip movements under the late Cretaceous NW-SE compression and the Paleogene NE-SW compression, respectively, despite the slight difference in strike of the two faults.

• Korean Journal of Plant Resources
• /
• v.34 no.4
• /
• pp.346-361
• /
• 2021

The range of D. spathulata identified in this survey was between N 35° 24' 58" ~ N 35° 26' 35", E 129° 05' 43" ~ E 129° 07' 04". It is located at an altitude of 98~592 m. The soil pH was strongly acidic in the range of 4.2~4.9, with a canopy openness of 18.56% and a chlorophyll index of 36.74 ± 2.80. As a result of the TWINSPAN analysis, 20 plots of 100 m² each were divided in 4 communities: Pinus densiflora community, Quercus monglica-Diabelia spathulata community, Quercus serrata-Diabelia spathulata community and Carpinus tschonoskii subassociation. The result of species diversity was 0.7615, and evenness and dominance were found to be 0.6077 and 0.3923, respectively. The height of D. spathulata is up to 3.4 m, and the average height is 1.1 m, with most of the species distributed as shrubbery and herbaceous. The average population density of the 20 plots was 1.635 individuals/m², the height range of flowering was 1.0 ~ 1.8 (aver. 1.39 m) and the rate of flowering was 27.37%. It's propagation pattern was mainly formed by extending the rhizome to the side, creating a colony of ground stems.

• Journal of the Korean Orthopaedic Association
• /
• v.56 no.6
• /
• pp.512-518
• /
• 2021

Purpose: This study compared the change in foraminal space on magnetic resonance imaging (MRI) and the clinical outcome after anterior cervical discectomy and fusion (ACDF) versus foraminotomy in cervical foraminal stenosis. Materials and Methods: A retrospective case-control study was conducted from January 2018 to March 2019 on 186 patients who underwent ACDF and foraminotomy. One hundred and two cases were selected considering age, sex, and body mass index. MRI was performed before and on the 5^th day after surgery to compare the changes in the foraminal diameter between the ACDF group (group A-51) and foraminotomy group (group B-51). Results: Between groups A and B, the average change in foraminal vertical diameter was 1.7 mm and 1.2 mm, respectively; group A was 0.5 mm larger difference (p=0.042). The average change in foraminal transverse diameter was 1.2 mm and 1.8mm, respectively; group B showed a 0.6 mm larger change (p=0.21). Both the neck disability index (NDI) and Japanese orthopaedic association (JOA) scores improved in both groups. Group A showed more improvement, but there was no significant difference (p=0.356, p=0.607, respectively). Conclusion: Foraminotomy is a useful option for patients with foraminal stenosis of the cervical spine because it showed comparable clinical and morphological results to ACDF and could minimize motion segment loss and muscle and ligament damage.

• Journal of Embryo Transfer
• /
• v.22 no.1
• /
• pp.53-61
• /
• 2007

This study was investigated factors affecting the pregnancy rates after transfer of pronuclear microinjected embryos for the production of transgenic Korean black goats. Embryo transfer was carried out in 343 recipient Korean black goats from September 1999 to June 2000. Estrus was induced by the insertion of intravaginal progesterone devices $CIDR^(R)$ for 2 weeks. A single injection of 400 IU equine chorionic gonadotropin was administered at 48h before $CIDR^(R)$ removal to increase the proportion of does cycling and ovulation rate. Good quality embryos were prepared by microinjection of DNA into the pronuclei of fertilized goat oocyte and cultured in vitro. Pronuclear microinjected $1{\sim}8$ cell stage embryos were surgically transferred into the oviducts of the recipient at day 4 or 5 following $CIDR^(R)$ removal, and morula to blastocyst stage embryos were surgically transferred into uterus at day 9. Pregnancy was diagnosed by transrectal ultrasound scanning at $20{\sim}30d$ and 8 weeks following embryo transfer. The pregnancy rate was affected by several factors, such as estrus induction, the number of previous transfer, transfer site, stage of CL (corpus luteum), the number of recipient CL, stage of embryos and the number of transferred embryo. The pregnancy rate was significantly higher in recipients that came into estrus naturally than recipients that induced to come into estrus with $CIDR^(R)$(59.1% vs. 36.8%; P<0.05). The pregnancy rate was higher when the embryos were transferred into the left oviduct than transferred into the right oviduct (42.9% vs. 35.3%; P<0.05). The pregnancy rate of recipients with $CH_1$ (early) stage corpus hemorrhagicum in ovary was hi틴or than recipient with $CH_3$ (late) stage hemorrhagicum (47.5% vs. 17.9%; P<0.01). Higher pregnancy rates were obtained by transfer of 1-cell stage embryos into oviduct while late blastocysts (51.6% vs. 66.7%; P<0.01) into uterus. The pregnancy rates when 3 embryos were transferred to recipients were significantly higher than when 2 embryos we.e transferred (47.6% vs. 27.0%; P<0.05). Although there were no significant difference among the group, adhesion of reproductive organs, uterine size, ovulation rate of recipients, presence of large follicle and difficulty of transfer affected pregnancy rate of recipient. Higher pregnancy rates were obtained in the recipients with $8{\sim}15m$ diameter uterine horn as compared to the recipients with <5m diameter or >20mm diameter uterine hem (38.9%, 20% vs. 18.2%), in the recipients with large follicle in the ovulated ovary ipsilaterally (53.6% vs. 37.1%) and in the transfer which was carried out easily (39.2% vs. 27.8%, 0%). In conclusion, the high rate of pregnancy was achieved following transfer of pronuclear microinjected embryos when three or four 1-cell stage embryos were transferred into oviduct with $CH_1$ stage corpus hemorrhagicum in the ovary of recipient which came into estrus naturally.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.2
• /
• pp.108-118
• /
• 2009

Statement of problem: Volume stability, microstructure reproducibility and fluidity along with compatibility with dental stone must be in consideration in order to use tissue conditioner as a material for functional impression. There are few studies concerning the influence of time factor in oral condition on surface roughness of the stone and optimal retention period in the oral cavity considering such changes in surface roughness. Purpose: The purpose of this study was to find out the influence of various kinds of tissue conditioner, its powder/liquid ratio and immersion time on surface roughness of the stone. Material and methods: Materials used in this study were the three kinds of tissue conditioners(Coe-Comfort, Visco-Gel, Soft-Liner) and were grouped into three: group R-mixed with standard powder/liquid ratio that was recommended by the manufacturers, group M-mixed with 20% more powder, group L-mixed with 20% less powder. Specimens were made with the size of 20 mm diameter and 2 mm width. Each tissue conditioner specimens were subdivided into 5 groups according to the immersion time(0 hour, 1 day, 3 days, 5 days, 7 days), completely immersed into artificial saliva and were stored under $37^{\circ}C$. Specimens of which the given immersion time elapsed were taken out and were poured with improved stone, making the stone specimens. Surface roughness of the stone specimens was measured by a profilometer. Results: Within the limitation of this study, the following results were drawn. 1. Major influencing factor on surface roughness of the stone model made from tissue conditioner was the retention period(contribution ratio($\rho$)=62.86%, P<.05) of the tissue conditioner in oral cavity to make functional impression. 2. In case of Coe-Comfort, higher mean surface roughness value of the stone model with statistical significance was observed compared to that of Soft-Liner and Visco-Gel as immersion time changes(P<.05). 3. In case of group L(less), higher mean surface roughness value of the stone model with statistical significance was observed compared to that of R(recommended) and M(more) group as immersion time changes(P<.05). Conclusion: We may conclude that as the retention period of time in oral cavity influences surface roughness of the stone model the most and as the kind of tissue conditioner and its P/L ratio may influence also, clinician should well understand the optimal retention period in oral cavity and choose the right tissue conditioner for the functional impression, thus making the functional impression with tissue conditioner usefully.

• Korean Journal of Soil Science and Fertilizer
• /
• v.10 no.3
• /
• pp.103-134
• /
• 1977

The physiological and biochemical role of potassium for upland crops according to recent research reports and the nutritional status of potassium in Korea were reviewed. Since physical and chemical characteristics of potassium ion are different from those of sodium, potassium can not completely be replaced by sodium and replacement must be limited to minimum possible functional area. Specific roles of potassium seem to keep fine structure of biological membranes such as thylacoid membrane of chloroplast in the most efficient form and to be allosteric effector and conformation controller of various enzymes principally in carbohydrate and protein metabolism. Potassium is essential to improve the efficiency of phoro- and oxidative- phosphorylation and involve deeply in all energy required metabolisms especially synthesis of organic matter and their translocation. Potassium has many important, physiological functions such as maintenance of osmotic pressure and optimum hydration of cell colloids, consequently uptake and translocation of water resulting in higher water use efficiency and of better subcellular environment for various physiological and biochemical activities. Potassium affects uptake and translocation of mineral nutrients and quality of products. potassium itself in products may become a quality criteria due to potassium essentiality for human beings. Potassium uptake is greatly decreased by low temperature and controlled by unknown feed back mechanism of potassium in plants. Thus the luxury absorption should be reconsidered. Total potassium content of upland soil in Korea is about 3% but the exchangeable one is about 0.3 me/100g soil. All upland crops require much potassium probably due to freezing and cold weather and also due to wet damage and drought caused by uneven rainfall pattern. In barley, potassium should be high at just before freezing and just after thawing and move into grain from heading for higher yield. Use efficiency of potassium was 27% for barley and 58% in old uplands, 46% in newly opened hilly lands for soybean. Soybean plant showed potassium deficiency symptom in various fields especially in newly opened hilly lands. Potassium criteria for normal growth appear 2% $K_2O$ and 1.0 K/(Ca+Mg) (content ratio) at flower bud initiation stage for soybean. Potassium requirement in plant was high in carrot, egg plant, chinese cabbage, red pepper, raddish and tomato. Potassium content in leaves was significantly correlated with yield in chinese cabbage. Sweet potato. greatly absorbed potassium subsequently affected potassium nutrition of the following crop. In the case of potassium deficiency, root showed the greatest difference in potassium content from that of normal indicating that deficiency damages root first. Potatoes and corn showed much higher potassium content in comparison with calcium and magnesium. Forage crops from ranges showed relatively high potassium content which was significantly and positively correlated with nitrogen, phosphorus and calcium content. Percentage of orchards (apple, pear, peach, grape, and orange) insufficient in potassium ranged from 16 to 25. The leaves and soils from the good apple and pear orchards showed higher potassium content than those from the poor ones. Critical ratio of $K_2O/(CaO+MgO)$ in mulberry leaves to escape from winter death of branch tip was 0.95. In the multiple croping system, exchangeable potassium in soils after one crop was affected by the previous crops and potassium uptake seemed to be related with soil organic matter providing soil moisture and aeration. Thus, the long term and quantitative investigation of various forms of potassium including total one are needed in relation to soil, weather and croping system. Potassium uptake and efficiency may be increased by topdressing, deep placement, slow-releasing or granular fertilizer application with the consideration of rainfall pattern. In all researches for nutritional explanation including potassium of crop yield reasonable and practicable nutritional indices will most easily be obtained through multifactor analysis.