• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.156-164
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• 2018

In order to investigate the upwelling and island effects following the wind storm events in the East Sea (i.e., Uljin-Ulleungdo-Dokdo line) during spring, we assessed the vertical and horizontal profiles of abiotic and biotic factors, including phytoplankton communities. The assessment was based on the Geostationary Ocean Color Imager (GOCI) and field survey data. A strong south wind occurred on May 3, when the lowest sea level pressure (987.3 hPa) in 2016 was observed. Interestingly, after this event, huge blooms of phytoplankton were observed on May 12 along the East Korean Warm Current (EKWC), including the in the offshore waters of Ulleungdo and Dokdo. Although the diatoms dominated the EKWC area between the Uljin coastal waters and Ulleungdo, the population density of raphidophytes Heterosigma akashiwo was high in the offshore waters of Ulleungdo-Dokdo. Based on the vertical profiles of Chlorophyll-a (Chl. a), the sub-surface Chl. a maximum appeared at 20 m depths between Uljin and Ulluengdo, whereas relatively high Chl. a was distributed equally across the entire water column around the waters of Ulleungdo and Dokdo islands. This implies that the water mixing (i.e., upwelling) at the two islands, that occurred after the strong wind event, may have brought the rapid proliferation of autotrophic algae, with nutrient input, to the euphotic layer. Therefore, we have demonstrated that a strong south wind caused the upwelling event around the south-eastern Korean peninsula, which is one of the most important role in occurring the spring phytoplankton blooms along the EKWC. In addition, the phytoplankton blooms may have potentially influenced the oligotrophic waters with discrete time lags in the vicinity of Ulleungdo and Dokdo. This indicates that the phytoplankton community structure in the offshore waters of Ulleungdo-Dokdo is dependent upon the complicated water masses moving related to meandering of the EKWC.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.6
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• pp.429-441
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• 2010

In this study, fire resistance of a fireproof material sprayed upon an immersed tunnel was experimentally evaluated under $HC_{inc}$ and IS0834(duration of 4 hours) fire scenarios. Under $HC_{inc}$ fire scenario, the maximum inner temperatures of a concrete specimen at the depth of 0, 25 and 50 mm from the interface between the structure and the fire-proofing layer were $311^{\circ}C$, $194^{\circ}C$ and $142^{\circ}C$ respectively. Similarly, the corresponding maximum temperatures under IS0834 fire scenario were $332^{\circ}C$, $222^{\circ}C$ and $179^{\circ}C$ respectively. From the results, it was revealed that the two different fire scenarios assumed in this study have almost the same fire capacity as each other in the maximum temperature concept. In addition, a structural analysis of the immersed tunnel under $HC_{inc}$ fire scenario was carried out to verify the effects of the fireproof material on its structural stability. Material loss and deterioration of a concrete specimen without any fire-proofing measure was also experimentally evaluated to obtain input parameters for the structural analysis under such a severe fire scenario. From the results, it was confirmed that the application of fireproof measures to the immersed tunnel is essential for its structural stability even under a severe fire scenario.

• The Journal of Engineering Geology
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• v.14 no.3 s.40
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• pp.301-311
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• 2004

This study is suggested a new dielectric tracer test method to understand geological structure of porous media and groundwater flow to use the dielectric constant which is one of electrical special quality of various geological materials. To measure their parameters, tracer material is made an ethanol mixing liquid(EML) having a same specific gravity of water. Also, soil materials are prepared a dielectric tracer test using the FDR system that could measure dielectric constant for saturated standard sand and river sand layers which have different initial porosity. To compare with their results, we discussed with the concentration variation of saline water having a saline concentration $3\%$ which is general tracer material by using the electro multi-meter system in the laboratory or field test. In two tracer experiment results, EML tracer test could confirm definitely EML concentration variation from each saturated soil layer as standard and river sands. However, tracer test of saline water $3\%$ concentration could not confirm permeating movement of water by degree of salinity change because these are settled at lower part column in a whole column area continuously. These causes are that specific gravity of saline water is heavier than water. That is, it could know that deposition of saline water is composed of lower part of soil column continuously independently of the direction of water into saturated soil material.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.89-112
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• 2002

The earliest reports of the use of electrical energy to directly stimulate bone healing seem to be in 1853 from England, the techniques involved the introduction of direct current into the non-united fracture site percutaneously via metallic needles, with subsequent healing of the defect. One endpoint of the periodontal therapy is to generate structure lost by periodontal diseases. Several procedural advances may support regeneration of attachment, however, regeneration of alveolar bone does not occur consistently. Therefore, factors which stimulate bone repair are areas for research in periodontal reconstructive therapy. Effects of cytokines or growth factors on bone repair are examples of such areas. Another one is electrical current which occurs in bone naturally, so that such bone may be particularly susceptible to electrical therapy. The purposes of this study were to observe the effects of electrical stimulation on the normal periodontium, to determine whether the electricity is the useful means for periodontal regeneration or not. Forty rats weighted about 100 gram were used and divided into 4 groups, the first group, there was no electrical stimulation with the connection of electrodes only. In the second group, there was stimulated by the 10 mA during 10 minutes per a day, in the third group was stimulated by the 25 mA , and the fourth by the 50 mA. At 3, 5, 10 and 15 days post-appliance , two rats in each group were serially sacrificed. and the maxillae and the mandible processed to paraffin, and the specimens were prepared with Hematoxylin-Eosin stain for the light microscopic evaluation. The results of this study were as follows : 1. There was the distinct reversal line on the lingual alveolar crest, whereas a little changes in the labial alveolarcrest to the duration and amount of currents. 2. In 50 mA group, the cells were highly concentrated at the apex of anterior teeth, and was observed the necrotic tissue. In posterior root apex, the hypercementosis was appeared, and newly formed cementum layer has been increased continuously with the time. 3. The periodontal ligament fiber and Sharpey's fiber were arranged in order, and the bone trabeculae were increased as the experiment proceeded by, relatively the bone marrows were decreased. 4. In the pulp tissue, the blood vessels were increased with blood congestion in the experimetal specimens remarkably, and the dentinal tubules were obstructed . 5. The osteoblasts in alveolar bone proper had been showed highly activity, and also observed the formation of bone trabeculea. In the conclusion, it was suggested that the electrical stimulation has influence on the periodontium and the pulp tissue. However, there might be the injurious effects.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.41-41
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• 2007

For use in spintronic materials, dilute magnetic semiconductors (DMS) are under consideration as spin injectors for spintronic devices[l]. $TiO_2$-based DMS doped by a cobalt, iron, and manganese et al. was recently reported to show ferromagnetic properties, even at temperatures above 300K and the magnetic ordering was explained in terms of carrier-induced ferromagnetism, as observed for a III-V based DMS. An anomalous Hall effect (AHE) and co-occurance of superparamagnetism in reduced Co-doped rutile $TiO_{2-\delta}$ films have also been reported[2]. Metal segregation in the reduced metal-doped rutile $TiO_2-\delta$ films still remains as problems to solve the intrinsic DMS properties. Superlattice films have been proposed to get dilute magnetic semiconductor (DMS) with intrinsicroom-temperature ferromagnetism. For a $TiO_2$-based DMS superlattice structure, each layer was alternately doped by two different transition metals (Fe and Mn) and deposited to a thickness of approximately $2.7\;{\AA}$ on r-$Al_2O_3$(1102) substrates by pulsed laser deposition. The r-$Al_2O_3$(1102) substrates with atomic steps and terrace surface were obtained by thermal annealing. Samples of $Ti_{0.94}Fe_{0.06}O_2$(TiFeO), $Ti_{0.94}Mn_{0.06}O_2$(TiMnO), and $Ti_{0.94}(Fe_{0.03}Mn_{0.03})O_2$ show a low remanent magnetization and coercive field, as well as superparamagnetic features at room temperature. On the other hand, superlattice films (TiFeO/TiMnO) show a high remanent magnetization and coercive field. An anomalous Hall effect in superlattice films exhibits hysisteresis loops with coercivities corresponding to those in the ferromagnetic Hysteresis loops. The superlattice films composed of alternating layers of $Ti_{0.94}Fe_{0.06}O_2$ and $Ti_{0.94}Mn_{0.06}O_2$ exhibit intrinsic ferromagnetic properties for dilute magnetic semiconductor applications.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.31-40
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• 2012

There are two methods to fabricate the readout electronic to a large-area CMOS image sensor (LACIS). One is to design and manufacture the sensor part and signal processing electronics in a single chip and the other is to integrate both parts with bump bonding or wire bonding after manufacturing both parts separately. The latter method has an advantage of the high yield because the optimized and specialized fabrication process can be chosen in designing and manufacturing each part. In this paper, LACIS chip, that is optimized design for the latter method of fabrication, is presented. The LACIS chip consists of a 3-TR pixel photodiode array, row driver (or called as a gate driver) circuit, and bonding pads to the external readout ICs. Among 4 types of the photodiode structure available in a standard CMOS process, $N_{photo}/P_{epi}$ type photodiode showed the highest quantum efficiency in the simulation study, though it requires one additional mask to control the doping concentration of $N_{photo}$ layer. The optimized channel widths and lengths of 3 pixel transistors are also determined by simulation. The select transistor is not significantly affected by channel length and width. But source follower transistor is strongly influenced by length and width. In row driver, to reduce signal time delay by high capacitance at output node, three stage inverter drivers are used. And channel width of the inverter driver increases gradually in each step. The sensor has very long metal wire that is about 170 mm. The repeater consisted of inverters is applied proper amount of pixel rows. It can help to reduce the long metal-line delay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.266-280
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• 1989

Gonadal maturation of the Korean pomfrets, Pampus echinogaster (Basilewsky) and Pampus argenteus (Euphrasen) were histologically investigated based on the samples captured in the East China Sea from January 1987 to December 1988. Gonadosomatic index (GSI) of P. echinogaster began to increase from March, and reached maximum between May and July. It began to decrease from July and reached mini-mum between August and February. P. argenteus had a similar cycle, however, P. argenteus has higher values in April than P. echinogaster. Hepatosomatic index (HSI) were positively related to GSI. HIS of P. echinogaster and P. argenteus reached maximum in $April\~July$ and $April\~August$, respectively, Fatness coefficient of two Pampus species were low in the summer, and high in the winter. Ovary is of saccular structure, and testis is of lobular structure. From February, the early oocyte (ca. $100\mu$ in diameter grows) rapidly at the germinal epithelium of ovarian sacs. From March to April the oocytes grew up to cu $400\~500\mu$ in diameter. At this stage, the yolk globules are accumulated rapidly in the cytoplasmic layer. From May, the oocytes roached ca. $650\~850\mu$ in diameter, and they are spawned in $May\~July$. After spawning the residual follicles and remained ripe eggs degenerate. From February, spermatogonia grows into spermatocyte on the epithelium of the testicular lobuli. From May, spermatozoa appeared and spawning occurs. After spawning, the epithelium is thickened and the remained spermatozoa degenerate. Annual reproductive cycle of two Pampus species could be divided into four successive stages: Growing stage ($March\~April$), Mature stage ($April\~May$), Ripe and spent stage ($June\~July$) and Recovery and resting stage ($August\~January$). Absolute fecundity of P. echinogaster was $9,441\~135,294$, and that of P. argenteus was $50,678\~221,894$. Absolute fecundity of two Pampus species were positively related to body length and total weight. Relative fecundity was positively related to body length, while it was reversely related to total weight. The increasing rate of absolute fecundity of P. echinogaster was lower than P. argenteus. In P. echinogaster half of female and male reached first maturity at body length of $15.0\~$17.9cm and $12.0\~14.9cm$, respectively. All of females and males reached first maturity at body length of $18.0\~20.9cm$ and $21.0\~23.9cm, respectively. In P. argenteus all of females and males reached first maturity at body length of 18.6cm and 16.7cm$, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.286-286
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• 2016

Hexagonal boron nitride (hBN) is a dielectric insulator with a two-dimensional (2D) layered structure. It is an appealing substrate dielectric for many applications due to its favorable properties, such as a wide band gap energy, chemical inertness and high thermal conductivity[1]. Furthermore, its remarkable mechanical strength renders few-layered hBN a flexible and transparent substrate, ideal for next-generation electronics and optoelectronics in applications. However, the difficulty of preparing high quality large-area hBN films has hindered their widespread use. Generally, large-area hBN layers prepared by chemical vapor deposition (CVD) usually exhibit polycrystalline structures with a typical average grain size of several microns. It has been reported that grain boundaries or dislocations in hBN can degrade its electronic or mechanical properties. Accordingly, large-area single crystalline hBN layers are desired to fully realize the potential advantages of hBN in device applications. In this presentation, we report the growth and transfer of centimeter-sized, nearly single crystal hexagonal boron nitride (hBN) few-layer films using Ni(111) single crystal substrates. The hBN films were grown on Ni(111) substrates using atmospheric pressure chemical vapor deposition (APCVD). The grown films were transferred to arbitrary substrates via an electrochemical delamination technique, and remaining Ni(111) substrates were repeatedly re-used. The crystallinity of the grown films from the atomic to centimeter scale was confirmed based on transmission electron microscopy (TEM) and reflection high energy electron diffraction (RHEED). Careful study of the growth parameters was also carried out. Moreover, various characterizations confirmed that the grown films exhibited typical characteristics of hexagonal boron nitride layers over the entire area. Our results suggest that hBN can be widely used in various applications where large-area, high quality, and single crystalline 2D insulating layers are required.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.537-539
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• 2006

We developed an 4.5" $192{\times}64$ active matrix organic light-emitting diode display on a glass using organic thin-film transistor (OTFT) switching-arrays with two transistors and a capacitor in each sub-pixel. The OTFTs has bottom contact structure with a unique gate insulator and pentacene for the active layer. The width and length of the switching OTFT is $800{\mu}m$ and $10{\mu}m$ respectively and the driving OTFT has $1200{\mu}m$ channel width with the same channel length. On/off ratio, mobility, on-current of switching OTFT and on-current of driving OTFT were $10^6,0.3{\sim}0.5\;cm^2/V{\cdot}sec$, order of 10 ${\mu}A$ and over 100 ${\mu}A$, respectively. AMOLEDs composed of the OTFT switching arrays and OLEDs made using vacuum deposition method were fabricated and driven to make moving images, successfully.

• Journal of the Korea Computer Graphics Society
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• v.24 no.1
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• pp.9-16
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• 2018

In this paper, we introduce a visualization framework for cell image data obtained from optical diffraction tomography (ODT), including a method for representing cell morphology in 3D virtual environment and a color mapping protocol. Unlike commonly known volume data sets, such as CT images of human organ or industrial machinery, that have solid structural information, the cell image data have rather vague information with much morphological variations on the boundaries. Therefore, it is difficult to come up with consistent representation of cell structure for visualization results. To obtain desired visual representation of cellular structures, we propose an interactive visualization technique for the ODT data. In visualization of 3D shape of the cell, we adopt a volume rendering technique which is generally applied to volume data visualization and improve the quality of volume rendering result by using empty space jittering method. Furthermore, we provide a layer-based independent rendering method for multiple transfer functions to represent two or more cellular structures in unified render window. In the experiment, we examined effectiveness of proposed method by visualizing various type of the cell obtained from the microscope which can capture ODT image and fluorescence image together.