• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.11
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• pp.18-24
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• 2000

(Ba,Sr)$TiO_3$ thin films have attracted great interest as new dielectric materials of capacitors for ultra-large-scale integrated dynamic random access memories (ULSI-DRAMs) such as 1 Gbit or 4 Gbit. In this study, inductively coupled $BCl_3/Cl_2/Ar$ plasmas was used to etch (Ba,Sr)$TiO_3$ thin films. RF power/dc bias voltage=600 W/-250 V and chamber pressure was 10 mTorr. The $Cl_2/(Cl_2+Ar)$ was fixed at 0.2 the (Ba,Sr)$TiO_3$ thin films were etched adding $BCl_3$. The highest (Ba,Sr)$TiO_3$ etch rate is $480{\AA}/min$ at 10 % $BCl_3$ to $Cl_2/Ar$. The change of Cl, B radical density measured by optical emission spectroscopy(OES) as a function of $BCl_3$ percentage in $Cl_2/Ar$. The highest Cl radical density was shown at the addition of 10% $BCl_3$ to $Cl_2/Ar$. To study on the surface reaction of (Ba, Sr)$TiO_3$ thin films was investigated by XPS analysis. Ion bombardment etching is necessary to break Ba-O bond and to remove $BaCl_2$. There is a little chemical reaction between Sr and Cl, but Sr is removed by physical sputtering. There is a chemical reaction between Ti and Cl, and $TiCl_4$ is removed with ease. The cross-sectional of (Ba,Sr)$TiO_3$ thin film was investigated by scanning electron microscopy (SEM), the etch slope is about 65~70$^{\circ}$.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.4
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• pp.365-375
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• 2006

The structural analysis for the secondary lining of tunnels is generally performed by a frame analysis model. This model requires a ground loosening load estimated by some empirical methods, but the load is likely to be subjective and too large. The ground load acting on the secondary lining is due to the loss of the supporting function of the first support members such as shotcrete and rockbolts. Therefore, the equilibrium condition of the ground and the first support members should be considered to estimate the ground load acting on the secondary lining. Ground-lining interaction model, shortly GLI model, is developed on the basis of the concept that the secondary lining supports the ground deformation triggered by the loss of the support capacity of the first support members. Accordingly, the GLI model can take into account the ground load reflecting effectively not only the complex ground conditions but the installed conditions of the first support members. The load acting on the secondary lining besides the ground load includes the groundwater pressure and earthquake load. For the structural reinforcement of the secondary lining based on the ultimate strength design method, the factored load and various load combination should be considered. Since the GLI model has difficulty in dealing with the factored load, introduced in this study is the superposition principle in which the section moment and force of the secondary lining estimated for individual loads are multiplied by the load factors. Finally, the design method of the secondary lining using the GLI model is applied to the case of a shallow subway tunnel.

• Parasites, Hosts and Diseases
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• v.55 no.5
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• pp.473-480
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• 2017

Plasmodium vivax merozoite surface protein-1 (PvMSP1) gene codes for a major malaria vaccine candidate antigen. However, its polymorphic nature represents an obstacle to the design of a protective vaccine. In this study, we analyzed the genetic polymorphism and natural selection of the C-terminal 42 kDa fragment within PvMSP1 gene ($PvMSP1_{42}$) from 77 P. vivax isolates, collected from imported cases of China-Myanmar border (CMB) areas in Yunnan province and the inland cases from Anhui, Yunnan, and Zhejiang province in China during 2009-2012. Totally, 41 haplotypes were identified and 30 of them were new haplotypes. The differences between the rates of non-synonymous and synonymous mutations suggest that $PvMSP1_{42}$ has evolved under natural selection, and a high selective pressure preferentially acted on regions identified of $PvMSP1_{33}$. Our results also demonstrated that $PvMSP1_{42}$ of P. vivax isolates collected on China-Myanmar border areas display higher genetic polymorphisms than those collected from inland of China. Such results have significant implications for understanding the dynamic of the P. vivax population and may be useful information towards China malaria elimination campaign strategies.

• The Korean Journal of Food And Nutrition
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• v.19 no.2
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• pp.161-168
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• 2006

The efficiency of six different extraction methods for the analysis of aroma components from pine needle(P. densiflora) was compared by gas chromatography-mass selective detector(GC-MSD). The six methods were dynamic headspace(DHS), reduced pressure headspace(RPHS), solid-phase microextraction(SPME), simultaneous distillation-extraction(SDE), supercritical fluid extraction(SFE) and pyrolysis distillation extraction(PDE). A total of 65 compounds were identified by using the six different extraction methods. These compounds are classified into six categories in terms of chemical functionality: 25 hydrocarbons, 16 alcohols, 9 carbonyls, 6 esters, 7 acids, and 2 ethers. The aroma compounds having low boiling point were more abundant in DHS, RPHS, and SPME extracts. On the other hand, the aroma compounds having high boiling point were more abundants in SDE, SFE and PDE extracts. The acid compounds were extracted by heat-based extraction methods such as SDE, SFE, PDE, but not by DHS, RPHS and SPME, which used neither solvent nor heat. The oxygenated terpens, hexanal, hexanol, and hexadienal were more abundant in DHS and RPHS extracts, compared with the other methods.

• Korean journal of communication and information
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• v.48
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• pp.90-108
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• 2009

While the term of the institution as social manifestation has been discussed intensively through various theoretical approaches over the last few years in Social Sciences, such a debate has been missing so far in Communication Sciences. This paper attempts a theoretical discussion about the media as an institution in the field of Communication Sciences by applying the theory of organizational sociological neo-institutionalism. This research started out with the question which influence exerts the media on organizations and participants. The media is understood as an institution in the sense of permanent monitoring systems which create a) normative expectations b) which become stronger in order to assert such normative expectations c) the norms are applied by the participants d) in this application process, the participants accept the organizations, look primarily for the chosen paragraphs and exert an influence to change the norms. Organizations orient themselves at the institutional rules, because this way, they want to gain legitimacy and support. The media unfold their influence on organizations through certain obligations in addition to the pressure of the participants who deal with the organization and the media. Thus, media cannot exert influence independent from the organizationbut the participants accept the situation, which is generated by the many conflicting processes within the organization, they analyse them and transfer them.

• Geotechnical Engineering
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• v.13 no.5
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• pp.89-100
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• 1997

It is very improtant to evaluate the reliable nonlinear deformational characteristics of soils not only in the analysis of geotechnical structures under working stress conditions but also for the soil dynamic problems. Field testings such as crosshole and pressuremeter tests can be used to determine the modulus of soils under in-situ conditions, but it is not possible to determine the modulus over the entire strain amplitude range. Laboratory methods such as resonant column 1 torsional shear test can be used to determine the modulus over the whole strain amplitude range, but it is very difficult to obtain the representative undisturbed samples on the sixte. For the reliable evaluation of nonlinear deformation characteristics of soils on a typical site, small strain modulus obtained from field testy and nomalized modulus reduction curve determined by laboratory bests need to be combined. In this paper, laboratory and Held testy were performed at a sixte which consisted of granite wearthered residual boils to evaluate the nonlinear deformational characteristics of coils such as the effects of strain amplitude, loading frequency, confining pressure and sample disturbance. It has been shorn that when the effects of these factors are properly taken into account, the stiffness values evaluated by various field and labrotary tests are comparable to each other fairly well. Finally, the procedure to evaluate the nonlinear deformstional characteristics of the sixte was proposed.

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.231-237
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• 2014

The supercritical fluids (SCFs) have been widely used for material synthesis and processing due to their remarkable properties including low viscosity, high diffusivity and low surface tension. Carbon dioxide is one of the suitable solvents in SCFs processes in terms of its advantages such as easy processibility (with low critical temperature and pressure), inexpensive, nonflammable, nontoxic, and readily available. However, it has generally low solubility for high molecular weight polymers with the exception of fluoropolymers and siloxane polymers. Therefore, hydrocarbon solvents and hydrochlorofluorocarbons have been used for various SCFs process by its high solubility for high molecular weight polymers. In this report, a PMMA/clay nanocomposites were fabricated by using supercritical fluid process. The $Na^+$-MMT(montmorillonites)was modified by a fluorinated surfactant which is able to enhance compatibility with the chlorodifluoromethane(HCFC-22) and thus, improve dispersability of the clay in the polymer matrix. The PMMA/fluorinated surfactant modified clay nanocomposite shows enhanced mechanical and thermal properties which characterized by X-raydiffraction(XRD), Thermo gravimetric analysis(TGA), Dynamic mechanical analysis (DMA) and Transmission electron microscopy (TEM).

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.597-604
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• 2019

Artificial neural networks are algorithms that simulate learning through interaction and experience in neurons in the brain and that are a method that can be used to produce accurate results through learning that reflects the characteristics of data. In this study, a model using deep neural network was presented to improve the predicted wind speed values in the meteorological dynamic model. The wind speed prediction improvement model using the deep neural network presented in the study constructed a model to recalibrate the predicted values of the meteorological dynamics model and carried out the verification and testing process and Separate data confirm that the accuracy of the predictions can be increased. In order to improve the prediction of wind speed, an in-depth neural network was established using the predicted values of general weather data such as time, temperature, air pressure, humidity, atmospheric conditions, and wind speed. Some of the data in the entire data were divided into data for checking the adequacy of the model, and the separate accuracy was checked rather than being used for model building and learning to confirm the suitability of the methods presented in the study.

• Journal of the Korean Institute of Intelligent Systems
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• v.3 no.2
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• pp.18-35
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• 1993

The water level control system of the steam generator in a pressurized water reactor and its control problems are analysed. In this work the stable control strategy during the low power operation and transient states is studied. To solve the problem, a fuzzy logic control method is applied as a basic algorithm of the controller. The control algorithm is based on the operator's knowledges and the experiences of manual operation for water level control at the compact nuclear simulator set up in Korea Atomic Energy Research Institute. From a viewpoint of the system realization, the control variables and rules are established considering simpler tuning and the input-output relation. The control strategy includes the dynamic tuning method and employs a substitutional information using the bypass valve opening instead of incorrectly measured signal at the low flow rate as the fuzzy variable of the flow rate during the pressure control mode of the steam generator. It also involves the switching algorithm between the control valves to suppress the perturbation of water level. The simulation results show that both of the fine control action at the small level error and the quick response at the large level error can be obtained and that the performance of the controller is improved.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.252-260
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• 2015

Ballasted track on an asphalt roadbed can be beneficial for its various effects such as (i) decreasing of roadbed thickness by dispersing train load; (ii) prevention of both strength reduction and weakening in roadbed system by preventing rainwater penetration; and (iii) reducing maintenance cost by preventing roadbed mud-pumping and frostbite. With these beneficial effects, ballasted track on asphalt roadbed has been widely used in Europe and Japan, and relevant research for applying such ballasted track on asphalt roadbed systems in Korea is ongoing. In this study, full-scale static and dynamic train load tests were performed to compare the performance of ballasted track on asphalt roadbed and ballasted track. The optimum thickness levels of asphalt and reinforced roadbeds, corresponding to the design criteria for reinforced roadbed of high-speed railway, was estimated using the FEM program ABAQUS. Test results show that the earth pressure on reinforced roadbed of ballasted track on the asphalt roadbed was relatively low compared with that of simple ballasted track. The elastic and plastic displacements of simple ballasted track on the asphalt roadbed were also lower than those of ballasted track. These test results may indicate that the use of ballasted track on asphalt roadbed is an advantageous system in view of long-term maintenance.