• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.831-840
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• 1997

Core/shell structured composite metal oxides of Fe2O3/MgO were prepared by thermal decomposition of Fe(acac)3 adsorbed on the surface of MgO cores. The morphology of the composites conformed to that of the MgO used as the cores. Broad powder X-ray diffraction peaks shifted toward larger d, large BET surface area (∼350 m2/g), and the size of crystalline domains in nano range (4 nm), all corroborate to the nanocrystallinity of the Fe2O3/MgO composite which was prepared by using nanocrystalline MgO as the core. By use of microcrystalline MgO as the core, microcrystalline Fe2O3/MgO composite was prepared, and it had small BET surface area of less than 35 m2/g. AFM measurements on nanocrystalline Fe2O3/MgO showed a collection of spherical aggregates (∼80 nm dia) with a very rough surface. On the contrary, microcrystalline Fe2O3/MgO was a collection of plate-like flat crystallites with a smooth surface. The nitrogen adsorption-desorption behavior indicated that microcrystalline Fe2O3/MgO was nonporous, whereas nanocrystalline Fe2O3/MgO was mesoporous. Bimodal distribution of the pore size became unimodal as the layer of Fe2O3 was applied to nanocrystalline MgO. The macropores in a wide distribution which the nanocrystalline MgO had were absent in the nanocrystalline Fe2O3/MgO. The decomposition of CCl4 was largily enhanced by the overlayer of Fe2O3 on nanocrystalline MgO making the reaction between nanocrystalline Fe2O3/MgO and CCl4 be nearly stoichiometric. The reaction products were environmentally benign MgCl2 and CO2. Such an enhancement was not attainable with the microcrystalline samples. Even for the nanocrystalline MgO, the enhancement was not attained, if not with the Fe2O3 layer. Without the layer of Fe2O3, it was observed that the nanocrystalline domain of the MgO transformed into microcrystalline one as the decomposition of CCl4 proceeded on its surface. It appeared that the layer of Fe2O3 on the particles of nanocrystalline Fe2O3/MgO blocked the transformation of the nanocrystalline domain into microcrystalline one. Therefore, in order to attain stoichiometric reaction between CCl4 and Fe2O3/MgO core/shell structured composite metal oxide, the morphology of the core MgO has to be nanocrystalline, and also the nanocrystalline domains has to be sustained until the core was exhausted into MgCl2.

• Phonetics and Speech Sciences
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• v.14 no.3
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• pp.41-49
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• 2022

The average acoustic distribution of American English speakers was statistically compared with the English-speaking patterns of gifted students in a Science Academy in Korea. By analyzing speech recordings, the duration time of which is much longer than in previous studies, this research identified the degree of acoustic proximity between the two parties and the predictability of English academic achievement of gifted high school students. Long-term spectral acoustic power distribution vectors were obtained for 2,048 center frequencies in the range of 20 Hz to 20,000 Hz by applying an long-term average speech spectrum (LTASS) MATLAB code. Three more variables were statistically compared to discover additional indices that can predict future English academic achievement: the receptive vocabulary size test, the cumulative vocabulary scores of English formative assessment, and the English Speaking Proficiency Test scores. Linear regression and correlational analyses between the four variables showed that the receptive vocabulary size test and the low-frequency vocabulary formative assessments which require both lexical and domain-specific science background knowledge are relatively more significant variables than a basic suprasegmental level English fluency in the predictability of gifted students' academic achievement.

• Convergence Security Journal
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• v.22 no.5
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• pp.95-105
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• 2022

The Army, Navy, and Air Force are making various efforts to develop a weapon system that incorporates the 4th industrial revolution technology so that it can be used in multi-domain operations. In order to effectively demonstrate the integrated combat power through the weapon system to which the new technology is applied, it is necessary to establish a network environment in which each weapon system can transmit and receive information smoothly. For this, it is essential to analyze the Information Exchange Requirement(IER) of each weapon system, but many IER analysis studies did not sufficiently reflect the various considerations of the actual tactical network. Therefore, this study closely analyzes the research methods and results of the existing information exchange requirements analysis studies. In IER analysis, the size of the message itself, the size of the network protocol header, the transmission/reception structure of the tactical network, the information distribution process, and the message occurrence frequency. In order to be able to use it for future IER prediction, we present a technique for calculating the information exchange requirement as a probability distribution using the Poisson distribution and the probability generating function. In order to prove the validity of this technique, the results of the probability distribution calculation using the message list and network topology samples are compared with the simulation results using Network Simulator 2.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.231-238
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• 2020

This paper investigates the soundness of porcelain insulators associated with the acoustic emission (AE) technique. The AE technique is a popular non-destructive method that measures and analyzes the burst energy that occurs mainly when a crack occurs in a high-frequency region. Typical AE methods require continuous monitoring with frequent sensor calibration. However, in this study, the AE technique excites a porcelain insulator using only an impact hammer, and it applies a high-pass filter to the signal frequency range measured only in the AE sensor by comparing the AE and the acceleration sensors. Next, the extracted time-domain signal is analyzed for the damage assessment. In normal signals, the duration is about 2ms, the area of the envelope is about 1,000, and the number of counts is about 20. In the damage signal, the duration exceeds 5ms, the area of the envelope is about 2,000, and the number of counts exceeds 40. In addition, various characteristics in the time and frequency domain for normal and damage cases are analyzed using the short-time Fourier transform (STFT). Based on the results of the STFT analysis, the maximum energy of a normal specimen is less than 0.02, while in the case of the damage specimen, it exceeds 0.02. The extracted high-frequency components can present dynamic behavior of crack regions and eigenmodes of the isolated insulator parts, but the presence, size, and distribution of cracks can be predicted indirectly. In this regard, the characteristics of the surface crack region were derived in this study.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.3
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• pp.565-573
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• 2012

To investigate the business corruption, the obtainments of the business data such as personnel, manufacture, accounting and distribution etc., is absolutely necessary. Futhermore, the investigator should have the systematic extraction solution from the business data of the enterprise database, because most company manage each business data through the distributed database system, In the general business environment, the database exists in the system with upper layer application and big size file server. Besides, original resource data which input by user are distributed and stored in one or more table following the normalized rule. The earlier researches of the database structure analysis mainly handled the table relation for database's optimization and visualization. But, in the point of the digital forensic, the data, itself analysis is more important than the table relation. This paper suggests the extraction technique from the table relation which already defined in the database. Moreover, by the systematic analysis process based on the domain knowledge, analyzes the original business data structure stored in the database and proposes the solution to extract table which is related incident.

• Fisheries and Aquatic Sciences
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• v.25 no.2
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• pp.101-116
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• 2022

The harvesting season of lompa fish, Thryssa baelama, through sasi, indigenous knowledge in resources management, in Haruku Village has become a socio-cultural event that attracts many people. The sasi of lompa fish has been conducted for hundreds of years. Information on the bioecology aspect of lompa fish is limited, while this information is crucial for lompa fish sustainability through the sasi approach. This study aimed to investigate some population parameters of lompa fish, its sustainability status, and proposed a sustainable management strategy for the lompa fishery of Haruku Village. Fish population parameter covers length-weight relationship, growth pattern, size distribution, sex ratio, and the body condition index. The sustainability status was assessed following the Rapfish approach. Fisheries management strategy was performed using a conceptual model framework based on Driver Pressure State Impact Response. The research shows that the total length varies between 9.2-14.3 cm. A high relationship was found between total length and weight, and the growth pattern was an allometric negative. There was a difference in sex ratio between males and females, with females dominant. The body condition index varies over time, probably due to reproductive status. The overall sustainability status was at fair condition (61.60%), with the ecological domain having the highest sustainable status (71.07%) and considered sustain. In comparison, the technological domain had the lowest sustainability status (52.58%) and was considered fair sustain. There were seven management strategies proposed for sustainable management for the lompa fishery.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.4
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• pp.21-30
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• 2010

In this paper, the parallel distributed rainfall runoff model(K-DRUM) using MPI(Message Passing Interface) technique was developed to solve the problem of calculation time as it is one of the demerits of the distributed model for performing physical and complicated numerical calculations for large scale watersheds. The K-DRUM model which is based on GIS can simulate temporal and spatial distribution of surface flow and sub-surface flow during flood period, and input parameters of ASCII format as pre-process can be extracted using ArcView. The comparison studies were performed with various domain divisions in Namgang Dam watershed in case of typoon 'Ewiniar' at 2006. The numerical simulation using the cluster system was performed to check a parallelization effectiveness increasing the domain divisions from 1 to 25. As a result, the computer memory size reduced and the calculation time was decreased with increase of divided domains. And also, the tool was suggested in order to decreasing the discharge error on each domain connections. The result shows that the calculation and communication times in each domain have to repeats three times at each time steps in order to minimization of discharge error.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.139-146
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• 2020

The domain of entrepreneurship has been dotted across various paradigms. Identifying and examining entrepreneurial intention and propensity to it spontaneously require the insight from the lens of psychological approach. The aim of this study is to examine the influence and impact of psychological factors on entrepreneurial intention; as it is found that in Bangladeshi context several entrepreneurship studies are undertaken, still the exploratory research on interplay between the psychological factors (i.e., self-confidence, locus of control, need for achievement, and tolerance for ambiguity) and entrepreneurial intention has been merely found. The study has chosen Bangladeshi university students as the unit of analysis and the ultimate sample size in this research is n=265. The current paper is a quantitative study where sampling method is followed by convenience sampling technique, and study data is collected through survey questionnaire. Data has been compiled into SPSS whereas, for hypotheses assessment, Smart PLS software is applied. The results reflect that self-confidence, locus of control, and need for achievement are revealed as contributory determinants of entrepreneurial intention while tolerance for ambiguity is found as an insignificant predictor. The current research is expected to offer an in-depth understanding about the significance of psychological factors in examining entrepreneurial intention.

• Journal of Pharmaceutical Investigation
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• v.28 no.3
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• pp.141-149
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• 1998

In order to reduce systemic side effects following administration, flurbiprofen was formulated as O/W microemulsion consisting of the surfactant, oil phase and aqueous phase. Particle size distribution, apparent viscosity, solubility and skin permeation of flurbiprofen in various vehicles and microemulsion were evaluated. The domain of O/W microemulsion s phase diagram had difference between oil types and the area of O/W microemulsion was wide distributed by adding to PG and cosurfactant than that of water alone. As increasing 10, 15 and 20% of Brij 97 content and 1, 2.5, 5% of oil content, the solubility of flurbiprofen in O/W microemulsions and various vehicles was $400{\sim}1,000$ and $10{\sim}500$ times higher than that of control. Also, apparent viscosity of soybean oil microemulsions was higher than that of IPM microemulsions and that of vehicle were increased as increasing vehicle content. Since skin permeation of flurbiprofen decreased as increasing viscosity, in each vehicle, it was not affected 2% ${\beta}-CD$ and decreased as increasing PG content and to 2, 5 and 10% of $HP-{\beta}-CD$. In O/W microemulsion, 5% soybean oil. 20% Brij 97 and 75% water(A-1) with high viscosity showed low skin penetration.

• Ocean and Polar Research
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• v.37 no.3
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• pp.179-188
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• 2015

This study was carried out to determine the optimal number of ARGO floats in the East Sea in order to maximize their applications. The dominant spatio-temporal scale, size of the domain, and the typical float lifetimes in the East Sea were taken into consideration. The mean spatial de-correlation scale of temperature on isobaric surfaces reaches about 60 km. The minimum necessary number of floats is about 82 on average in order to secure independent ARGO profiles with the de-correlation scale. Considering the float lifetimes, about 27 floats per year should be deployed to maintain the 82 ARGO float array every year. To obtain spatially uniform distribution of ARGO float data, mean residence time and dispersion rate (basin area/residence time) of ARGO floats were evaluated in each basin of the East Sea. A faster (slower) dispersion rate requires more (less) ARGO floats to maintain the spatially uniform number of floats. According to the analysis, it is likely that the optimal ratio of the number of floats for each basin is 1:2:4 corresponding to Ulleung Basin:Yamato Basin:Japan Basin. In order to maintain relatively uniform ARGO observing networks, it is necessary to establish a long-term plan for deployment strategy based on float pathways and the dispersion rate parameters estimated by using currently active ARGO float trajectory data as well as reanalysis data.