• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.10 s.113
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• pp.929-934
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• 2006

In the paper, we suggest a simpler synthesis technique for capacitively-coupled match circuit(CCMC) which have a function of DC block and impedance matching simultaneously, and introduce a stability margin analysis technique for designing microwave amplifier under conditionally stable state. Stability margin analysis is used to determine optimum match point that ensure maximum gain under the given stability margin. It can reduce time consuming work for selecting match points in the conditionally stable state. Also, suggested miniaturization scheme of matching network is distinguished from previous work with respect to reducing deterministic parameters for CCMC synthesis. To verify utility of suggested method, 24 GHz gain block is fabricated under conditionally stable state using an internal thin-film fabrication process, Measured results show a stable gain of 10 dB and flatness of 1 dB, which is well coincident with simulated one.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.1
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• pp.97-109
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• 2007

Vertical distribution and optical properties of atmospheric aerosols above the Korean peninsula are quite important to estimate effects of aerosol on atmospheric environment and regional radiative forcing. For the first time in Korea, vertical microphysical properties of atmospheric aerosol obtained by inversion algorithm were analyzed based on optical data of multi-wavelength Raman lidar system developed by the Advanced Environmental Monitoring Research Center (ADEMRC), Gwangju Institute Science and Technology (GIST). Data collected on 14 June 2004 at Gwangju ($35.10^{\circ}N,\;126.53^{\circ}E$) and 27 May 2005 at Anmyeon island ($36.32^{\circ}N,\;126.19^{\circ}E$) were used as raw optical data for inversion algorithm. Siberian forest fire smoke and local originated haze were observed above and within the height of PBL, respectively on 14 June 2004 according to NOAA/Hysplit backstrajectory analysis. The inversion of lidar optical data resulted in particle effective radii around $0.31{\sim}0.33{\mu}m$, single scattering albedo between $0.964{\sim}0.977$ at 532 nm in PBL and effective radii of $0.27{\mu}m$ and single scattering albedo between $0.923{\sim}0.924$ above PBL. In the case on 27 May 2005, biomass burning from east China was a main source of aerosol plume. The inversion results of the data on 27 May 2005 were found to be particle effective radii between $0.23{\sim}0.24{\mu}m$, single scattering albedo around $0.924{\sim}0.929$ at 532 nm. Additionally, the inversion values were well matched with those of Sun/sky radiometer in measurement period.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.8 no.4
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• pp.121-138
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• 1983

This study beings with investigations of the purpose and background of the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers of 1978 stipulated in London(STCW Convention) which will be put into effect internationally on and after the 28th April, 1984. I tried to confirm those common points on requirements of the qualification between the radio officer regulated in the STCW Convention and the radiocommunication operator's general cergifications administration is taken as a model for the comparative analysis, as Korea and Japan have meny similar aspects, especially legal and social aspects. Therefore, as one of urgent tasks of Korean Telecommunications Administraion preparing for the STCW Convention, I stressed on the partial amendment of the Radio Law. The gist of major amendment proposed is as follows : (1) to introduce a new system on the radio operator for ship stations. (2) to adapt the general cergificate of radiocommunication operator. This year, 1983, was proclaimed World Communications Year (WCY'83) by the U.N to provide the opportunity for all countries to undertake an in-depth review and analysis of their policies on communications development. In this regards, there must be a stimulation for the accelerated development of Communications Infrastructures in Korea.

• Toxicological Research
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• v.34 no.2
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• pp.163-172
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• 2018

Air pollution is increasing, along with consumption of fossil fuels such as coal and diesel gas. Air pollutants are known to be a major cause of respiratory-related illness and death, however, there are few reports on the genotoxic characterization of diverse air pollutants in Korea. In this study, we investigated the mutagenic activity of various particles such as diesel exhaust particles (DEP), combustion of rice straw (RSC), pine stem (PSC), and coal (CC), tunnel dust (TD), and road side dust (RD). Ultra-fine particles (UFPs) were collected by the glass fiber filter pad. Then, we performed a chemical analysis to see each of the component features of each particulate matter. The mutagenicity of various UFPs was determined by the Ames test with four Salmonella typhimurium strains with or without metabolic activation. The optimal concentrations of UFPs were selected based on result of a concentration decision test. Moreover, in order to compare relative mutagenicity among UFPs, we selected and tested DEP as mutation reference. DEP, RSC, and PSC induced concentration-dependent increases in revertant colony numbers with TA98, TA100, and TA1537 strains in the absence and presence of metabolic activation. DEP showed the highest specific activity among the particulate matters. In this study, we conclude that DEP, RSC, PSC, and TD displayed varying degrees of mutagenicity, and these results suggest that the mutagenicity of these air pollutants is associated with the presence of polycyclic aromatic hydrocarbons (PAHs) in these particulate matters.

• Asian Journal of Atmospheric Environment
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• v.5 no.2
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• pp.97-104
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• 2011

Recent studies have indicated that the observed nitric acid ($HNO_3$) uptake rates ($R_{HNO_3}$) onto dust particles are much slower than $R_{HNO_3}$ used in the previous modeling studies. Three factors that possibly affect $R_{HNO_3}$ onto dust particles are discussed in this study: (1) the magnitude of reaction probability of $HNO_3$ (${\gamma}_{HNO_3}$), (2) aerosol surface areas, and (3) gas-phase $HNO_3$ mixing ratio. Through the discussion presented here, it is shown that the use of accurate ${\gamma}_{HNO_3}$ is of primary importance. We suggest that the use of ${\gamma}_{HNO_3}$ values between $\sim10^{-3}$ and $\sim10^{-5}$ produces more realistic results than the use of ${\gamma}_{HNO_3}$ values between $\sim10^{-1}$ and $\sim10^{-2}$ does, more accurately modeling the nitrate formation characteristics on/in dust particles. We also discuss two different types of aerosol surface area, active and geometric, since the use of different aerosol surface areas often leads to an erroneous result in $R_{HNO_3}$. In addition, the levels of the gas-phase $HNO_3$ are investigated with the example cases of TRACE-P DC-8 flights in East Asia. The $HNO_3$ levels were found to be relatively high, indicating that they can not limit nitrate formation in dust particles.

• KIISE Transactions on Computing Practices
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• v.23 no.2
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• pp.85-96
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• 2017

IoT-Cloud service, integration of Internet of Things (IoT) and Cloud, is becoming a critical model for realizing creative and futuristic application services. Since IoT machines have little computing capacity, it is effective to attaching public Cloud resources for realizing IoT-Cloud service. Furthermore, utilizing containers and adopting a microservice architecture for developing IoT-Cloud service are useful for effective realization. The quality of microservice based IoT-Cloud service is affected by service function chaining which inter-connects each functions. For example, an issue with some of the functions or a bottleneck of inter-connection can degrade the service quality. To ensure functionality of the entire service, various test procedures considering various service environments are required to improve the service continuously. Hence in this paper, we introduce experimental realization of continuous integration based on DevOps and employ application performance monitoring for Node.js based IoT-Cloud service. Then we discuss its effectiveness.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.2
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• pp.135-143
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• 2018

Tumor necrosis $factor-{\alpha}$ ($TNF{\alpha}$) and the angiotensin system are involved in inflammatory diseases and may contribute to acute kidney injury. We investigated the mechanisms by which $TNF{\alpha}$-converting enzyme (TACE) contributes to lipopolysaccharide (LPS)-induced renal inflammation and the effect of TACE inhibitor treatment on LPS-induced cellular injury in human renal proximal tubule epithelial (HK-2) cells. Mice were treated with LPS (10 mg/kg, i.p.) and HK-2 cells were cultured with or without LPS ($10{\mu}g/ml$) in the presence or absence of a type 1 TACE inhibitor ($1{\mu}M$) or type 2 TACE inhibitor ($10{\mu}M$). LPS treatment induced increased serum creatinine, $TNF{\alpha}$, and urinary neutrophil gelatinase-associated lipocalin. Angiotensin II type 1 receptor, mitogen activated protein kinase (MAPK), and TACE increased, while angiotensin-converting enzyme-2 (ACE2) expression decreased in LPS-induced acute kidney injury and LPS-treated HK-2 cells. LPS induced reactive oxygen species and the down-regulation of ACE2, and these responses were prevented by TACE inhibitors in HK-2 cells. TACE inhibitors increased cell viability in LPS-treated HK-2 cells and attenuated oxidative stress and inflammatory cytokines. Our findings indicate that LPS activates renin angiotensin system components via the activation of TACE. Furthermore, inhibitors of TACE are potential therapeutic agents for kidney injury.

• KIISE Transactions on Computing Practices
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• v.22 no.11
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• pp.547-558
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• 2016

Construction of multi-site Cloud Infrastructure with OpenStack, the most popular cloud open source project with various ICT infrastructure technologies, has operational inefficiency due to installation complexity and geographical limitation. To address this inefficiency, we gradually developed automated installation/configuration tools to automate installation/configuration of Linux and OpenStack by complying with DevOps methodology over a multi-site OpenStack testbed called OF@KOREN SmartX Playground. However, the pre-developed installation tools can be used only for limited cases. Therefore, we designed and developed a prototype of SmartX Provisioning Framework which could conducts Playground-wide provisioning flexibly by following three steps of resource management in Software-defined Infrastructure. We verified the efficiency of the provisioning functionality of the framework by demonstrating an example of automated multi-site cloud construction.

• Journal of the Korean Vacuum Society
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• v.20 no.4
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• pp.271-275
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• 2011

The role and effect of Sb surfactant on structure and properties of p type gallium nitride (GaN) epilayers have been investigated. It was found that there was a increase of hole concentration with Sb surfactant, compared to typical Mg-doped p-GaN. The structural and optical quality of p-GaN epilayers were accessed by x-ray diffraction, photoluminescence and atomic force microscope measurements. The results clearly show that the increase in hole concentration with Sb surfactant can be resulted from decrease in the dislocations and nitrogen point defects.

• Lingua Humanitatis
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• v.8
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• pp.331-367
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• 2006

In this paper I attempted to investigate the matters related with the clarification of the close relationship between writing system and pronunciation. On the way of pursuing the research on the subject I found the fact that the same topic has been the main academic target in Korea. There have been some remarks about English alphabets and pronunciation. Nevertheless, the relation between alphabet codes and pronunciation tokens wasn't considered as the main key to master the English pronunciation correctly and completely. As the main target of this paper I argue that it is necessary to comprehend the connection. Then, we can recognize the significant role of alphabetic structure for understanding the gist of pronunciation exercise. This paper is classified into four parts. Each part consists of the material to affirm the fact that writing system should be the inevitable equivalent of sound system, and vice versa. In the first section I show that the development of the way of pronouncing English words is closely related with the endeavors of the scholars. While performing the survey of the studies about the alphabetic structure of the age many scholars found that the spelling construction was recorded without any common denominator. Thus, they not only sought to stage the bedrock for the standard written form of words but also to associate the alphabet letters with phonetic features. Secondly I mention the negative aspect of the 'only spelling based English pronunciation education' for the educational goal of 'Phonics methodology.' In this part I suggest the essentiality of phonemic properties with the phonetic prospect: phonemic awareness. Thirdly I refer to the standardization of the spelling system of English. As the realm of application of the language is extended toward the various professional areas such as commercial, scientific, and cultural spheres, it is quite natural to assume that the usage of the language will be transformed according to the areas in the world. Fourthly I introduce the first English-Korean grammar book with the section of 'the introduction to English pronunciation.' At the chapter the author explained the sound features of English based on the regulation of 'Scientific Alphabet' of U.S.A. In the transcribing system all the symbols were postulated on the basis of the English alphabet form instead of the separate phonetic signs of IPA.