• Journal of the Korean association of regional geographers
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• v.11 no.2
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• pp.278-290
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• 2005

This study deals with the geomorphic, environmental and land use changes by comparative analysis using Landsat TM images of 1988 year and ETM ones of 2002 year, partly together with the new Quick Bird images having 60cm resolution for more detail analysis, focusing on the Oncheon gun(county) in Pyeongnam Province, west coast zone of North Korea. The main analysis methodology is neural network classification, which is more advanced techniques for the classification of land cover and land use, with higher accuracy rate and lower errors. The TM images of 1988 year show, mainly, the on-construction tide embank for the reclamation at Gwangryangman bay and salt farm on the reclaimed tidal flat. But, ETM images of 2002 year present stabilized reclaimed land, salt farm and rice field, recently transformed from salt farm. Especially, new tidal land has been naturally developed on the coastal shallow out of tide embank and salt farm. The results of the study may help to database coastal environmental changes and to support for reasonable and productive land use of North Korea, and to manage and plan unified national land in the near future.

• Journal of the Korean Vacuum Society
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• v.11 no.3
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• pp.183-188
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• 2002

In the present study AI$(CH_3)_3)$films were deposited by the ALD technique using trimethylaluminum(TMA) and ozone to improve the quality of the AI$(CH_3)_3)$ films, since the $OH^-$ radicals existing in the AI$(CH_3)_3)$ films deposited using TMA and $H_2O$ degrade the physical and the dielectric properties of the AI$(CH_3)_3)$ film. The XPS analysis results indicate that the $OH^-$ radical concentration in the AI$(CH_3)_3)$film deposited using $O_3$is lower than that using $H_2O$. The etch rate of the AI$(CH_3)_3)$film deposited using $O_3$is also lower than that using $H_2O$, suggesting that the chemical inertness of the former is better than the latter. The MIS capacitor fabricated with the TiN conductor and the $Al_2$O$_3$dielectrics formed using $O_3$offers lower leakage current, better insulating property and smaller flat band voltage shift $({\Delta}V_{FB})$.

• Journal of the Korean Vacuum Society
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• v.12 no.3
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• pp.168-173
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• 2003

Recently, according to the rapid progress in Flat-panel-display industry, there has been a growing interest in the poly-Si process. Compared with a-Si, poly-Si offers significantly high carrier mobility, so it has many advantages to high response rate in Thin Film Transistors (TFT's). We have investigated a new process for the high temperature Solid Phase Crystallization (SPC) of a-Si films without any damages on glass substrates using thin film heater. because the thin film heater annealing method is a very rapid thermal process, it has very low thermal budget compared to the conventional furnace annealing. therefore it has some characteristics such as selective area crystallization, high temperature annealing using glass substrates. A 500 $\AA$-thick a-Si film was crystallized by the heat transferred from the resistively heated thin film heaters through $SiO_2$ intermediate layer. a 1000 $\AA$-thick $TiSi_2$ thin film confined to have 15 $\textrm{mm}^{-1}$ length and various line width from 200 to 400 $\mu\textrm{m}$ was used as the thin film heater. By this method, we successfully crystallized 500 $\AA$-thick a-Si thin films at a high temperature estimated above $850^{\circ}C$ in a few seconds without any thermal deformation of g1ass substrates. These surprising results were due to the very small thermal budget of the thin film heaters and rapid thermal behavior such as fast heating and cooling. Moreover, we investigated the time dependency of the SPC of a-Si films by observing the crystallization phenomena at every 20 seconds during annealing process. We suggests the individual managements of nucleation and grain growth steps of poly-Si in SPC of a-Si with the precise control of annealing temperature. In conclusion, we show the SPC of a-Si by the thin film heaters and many advantages of the thin film heater annealing over other processes

• Korean Journal of Fisheries and Aquatic Sciences
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• v.6 no.1_2
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• pp.76-80
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• 1973

Cyclina sinensis is an edible bivalve inhabiting wide tidal flats which are exposed to the air at ebb tide along the western coast of Korea. Over the period of June to September 1971, some specimens from a tidal flat near Inchon were submerged in sea water with various concentrations of ammonium hydroxide added and careful observations were made on their fertilization, early development, and metamorphosis of the larvae. The highest rate of fertilization was demonstrated by individuals treated with 1/1000 normal solution of ammonium hydroxide and their fertilized eggs followed normal development, i.e., two cell stage 1.5 hours after fertilization, blastular stage after 4 hours, and trochophore stage after 6 hours. Within 24 hrs after fertilization C. sinensis larvae have acquired the form of early straight-hinge veliger with the mean prodissoconch I with the length of $110\mu$. It takes seven days to get the umbo stage with the mean shell length of $190\mu$ and twenty days to get the morphosing stage with the mean shell length of $260\mu$. The larvae were cultured to the metamorphosing stage with the shell length of $270\mu$ in the laboratory condition.

• Journal of Digital Contents Society
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• v.12 no.1
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• pp.23-32
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• 2011

For the past few years, unlike wireless widespread United States and Japan, expensive cost and platform of the mobile web carrier underground and self-centered made achievement of domestic mobile web market sluggish. Nowadays, more and more people pay attention to the mobile web service because of the increased quality of wireless internet, development of mobile device and variety of the flat-rate payment system. However, another big problem is that mobile web is too hard to use. Also, the poor content of mobile web service is an extremely serious problem. In this paper, we put forward a new method for easy to access mobile web service which is use WINC expansion numbers and users can use these numbers to shit their own website. Along with the benefits of purchase WINC number general users are able to make website and control their website at less time and energy.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1659-1663
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• 2003

$Al_2O_3$ thin films were grown on H-terminated Si(001) substrates using dimethylaluminum isopropoxide [DMAl: $(CH_3)_2AlOCH(CH_3)_2$], as a new Al precursor, and water by atomic layer deposition (ALD). The selflimiting ALD process by alternate surface reactions of DMAI and $H_2O$ was confirmed from measured thicknesses of the aluminum oxide films as functions of the DMAI pulse time and the number of DMAI-$H_2O$ cycles. Under optimal reaction conditions, a growth rate of ~1.06 ${\AA}$ per ALD cycle was achieved at the substrate temperature of $150\;^{\circ}C$. From a mass spectrometric study of the DMAI-$D_2O$ ALD process, it was determined that the overall binary reaction for the deposition of $Al_2O_3\;[2\;(CH_3)_2AlOCH(CH_3)_2\;+\;3\;H_2O\;{\rightarrow}\;Al_2O_3\;+\;4\;CH_4\;+\;2\;HOCH(CH_3)_2]$can be separated into the following two half-reactions: where the asterisks designate the surface species. Growth of stoichiometric $Al_2O_3$ thin films with carbon incorporation less than 1.5 atomic % was confirmed by depth profiling Auger electron spectroscopy. Atomic force microscopy images show atomically flat and uniform surfaces. X-ray photoelectron spectroscopy and cross-sectional high resolution transmission electron microscopy of an $Al_2O_3$ film indicate that there is no distinguishable interfacial Si oxide layer except that a very thin layer of aluminum silicate may have been formed between the $Al_2O_3$ film and the Si substrate. C-V measurements of an $Al_2O_3$ film showed capacitance values comparable to previously reported values.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.245-252
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• 2017

Recently, structures such as large retailers, outlets and warehouses have been increasing in accordance with changes in consumption patterns. Since these structures include ultra-flat slab members, they are thoroughly managed to control slab cracking by the plastic and drying shrinkage. In order to control the cracking of the slab member, a chemical crack reduction method is used. In particular, the use of the shrinkage reducing agent has been examined. However, domestic research results are limited. In this study, the shrinkage properties of concrete using shrinkage reducing agent and the drying shrinkage properties according to the mixing factors were investigated. The performance of domestic shrinkage reducing agent was appeared similar to that of overseas high-grade shrinkage reducing agent. As the shrinkage reducing agent usage increased, the drying shrinkage reduction effect increased. At the age of 100 days, the dry shrinkage rate of specimen with the shrinkage reducing agent of 1.5%was shown about half that of the specimen without the shrinkage reducing agent. The shrinkage reducing agent was gound to have no specific performance change for the use of the admixture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.111-118
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• 2003

The transmit adaptive array requires the forward link channel information for evaluating the optimum transmit weight vector in which a feedback channel provides transmitter with the forward link channel information. The larger transmit adaptive array is, the higher required rate of feedback channel is. Therefore we consider the system that the N-transmit antenna system is expanded to the 2N-transmit antenna system, while the feedback channel is maintained as that of N-transmit antenna system. The increase of the number of antennas can produce the additional diversity gain, however the insufficient feedback bits assigned to each antenna aggravates the quantization error. In this paper, we propose the transmit antenna selection in order to improve the performance of transmit adaptive array having an insufficient feedback channel information. The effective method to transmit the weight vector is also introduced. System performances are investigated for the case of N=4 corresponding to the antenna selection diversity schemes on the flat fading channel and the multipath fading channel. The simulation results show that the proposed scheme can improve the system performance by 1 dB when the N is expanded to the 2N, while the feedback channel is restricted to that of N-transmit antenna system.

• Journal of Energy Engineering
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• v.25 no.2
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• pp.1-20
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• 2016

A condensation heat transfer model is very important for the safety analysis of nuclear power plants. Especially, condensation under the presence of noncondensable gases (NCGs) is an important issue in nuclear safety because the presence of even a small quantity of NCGs in the vapor largely reduces the condensation rate. In this study, the condensation heat transfer model of the severe accident analysis code MELCOR 1.8.6 has been assessed using a set of condensation experiments performed under the thermal-hydraulic conditions similar to those inside a containment during design-basis accidents or severe accidents. Experiment conditions are categorized into 4 types according to the shape of the condensation surface: vertical flat plates, outer surface of vertical pipes, inner surface of vertical pipes, the inner surface of horizontal pipes. The results of the calculations show that the MELCOR code generally under-predicts the condensation heat transfer except the condensation on inner surface of vertical pipes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1313-1318
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• 2006

The mechanism fur the surface film formation was studied by in situ Atomic Force Microscopy (AFM) observation of a highly oriented pyrolytic graphite (HOPG) basal plane surface during cyclic voltammetry at a slow scan-rate of 0.5 mV $s^{-1}$ in 1 moi $dm^{-3}$ (M) $LiPF_6$ dissolved in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC). Decomposition of the electrolyte solution began at a potential around 2.15 V vs. $Li^+$/Li on step edges. In the potential range 0.95-0.8 V vs. $Li^+$/Li, flat areas (hill-like structures) and large swelling appeared on the surface. It is considered that these two features were formed by the intercalation of solvated lithium ions and their decomposition beneath the surface, respectively. At potentials more negative than 0.80 V vs. $Li^+$/Li, particle-like precipitates appeared on the basal plane surface. After the first cycle, the thickness of the precipitate layer was 30 nm. The precipitates were considered to be decomposition of the lithium salt ($LiPF_6$) and solvent molecules (EC and DEC), and to have an important role in suppressing further solvent decomposition on the basal plane.