• Journal of Astronomy and Space Sciences
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• 제28권4호
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• pp.273-284
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• 2011

A method of stellar source selection for validating the quality of image is investigated for a low Earth orbit optical remote sensing satellite. Image performance of the optical payload needs to be validated after its launch into orbit. The stellar sources are ideal source points that can be used to validate the quality of optical images. For the image validation, stellar sources should be the brightest as possible in the charge-coupled device dynamic range. The time delayed and integration technique, which is used to observe the ground, is also performed to observe the selected stars. The relations between the incident radiance at aperture and V magnitude of a star are established using Gunn & Stryker's star catalogue of spectrum. Applying this result, an appropriate image performance index is determined, and suitable stars and areas of the sky scene are selected for the optical payload on a remote sensing satellite to observe. The result of this research can be utilized to validate the quality of optical payload of a satellite in orbit.

• 한국IT서비스학회지
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• 제12권4호
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• pp.267-287
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• 2013

As the online bookstore market has been saturated and the level of competition has become more intense, maintaining competitive advantage by mitigating consumers' perceived risks can be considered as one of good alternative strategies a company should use. Although studies that identify the types of consumers' perceived risks in the context of online bookstores as well as validate the relationships between perceived risk and its antecedent/consequent factors in an integrated manner are strongly required, there has been less attention paid to these matters. Therefore, based on previous literature, we identify five types of perceived risks (financial, performance, online payment, delivery, and seller's response risk) and validate the impacts of online bookstore specific characteristics and user specific characteristics on perceived risk. In addition, we also verify causal relationship between perceived risk and intention to use online bookstores. The results of PLS test using 108 samples collected from undergraduate and graduate students confirm that perceived risk has a negative impact on intention to use and four antecedents (reputation, service quality, self-efficacy, and user experience) are significantly related to perceived risk.

• 셀메드
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• 제8권3호
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• pp.15.1-15.5
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• 2018

Helminthiasis is one of the most common worm diseases which causes a range of adverse health problems in humans. Ayurveda is one of the most prominent and ancient systems of traditional medicines in India. Most Ayurvedic drugs used against intestinal helminths have been developed by traditional wisdom and therefore lack a proper validation through controlled studies. The aim of the present study was to scientifically validate the in vitro efficacy of three common Indian Ayurvedic anthelmintic drugs, viz. Krimimudgar Ras, Kriminol and Vidangasava in relation to the synthetic broad-spectrum anthelmintic drugs, praziquantel and albendazole. The in vitro testing of Ayurvedic anthelmintics was done against an intestinal cestode, Raillietina sp. and a nematode, Syphacia obvelata, employing 10 mg/ml, 30 mg/ml and 50 mg/ml concentrations of each medicine. The anthelmintic efficacy was judged on the basis of paralysis and mortality time of worms after exposing to these Ayurvedic drugs. Of the three tested Ayurvedic medicines, Krimimudgar ras (KR) showed the most prominent efficacy, against both the cestode and nematode parasites. At 50 mg/ml concentration, KR caused mortality of cestodes in $7.53{\pm}0.15hr$, and of nematodes in $7.61{\pm}0.19hr$. Vidangasava was found to be comparatively less effective against the tested helminth parasites. The results of this study indicate that Ayurvedic formulations do possess significant anthelmintic effects, however, an evidence-based research is required to validate all currently used Ayurvedic anthelmintics, using proper controlled studies.

• Advances in nano research
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• 제9권1호
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• pp.59-67
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• 2020

Filter cake formation during rotary drilling operation is an unavoidable scenario, hence there is need for constant improvement in the approaches used in monitoring the cake thickness growth in order to prevent drill-string sticking. This study proposes an improved model that predicts the growth of mud cake thickness overtime with the consideration of the addition of nanoparticles in the formulated drilling fluid system. Ferric oxide, titanium dioxide and copper oxide nanoparticles were used in varying amounts (2 g, 4 g and 6 g), and filtration data were obtained from the HPHT filtration test. The filter cakes formed were further analyzed with scanning electron microscope to obtain the morphological characteristics. The data obtained was used to validate the new filtrate loss model. This model specifically presents the concept of time variation in filter cake formation as against the previous works of constant and definite time. Regression coefficient which is a statistical measure was used to validate the new model and the predicted results were compared with the API model. The new model showed R² values of 99.9%, and the predictions from the proposed filtration model can be said to be more closely related to the experimental data than that predicted from the API model from the SSE and RMSE results.

• 한국정보시스템학회지:정보시스템연구
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• 제22권3호
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• pp.43-58
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• 2013

This work investigates factors that may affect the choice of real options by ERP project managers. Financial theory suggest that these factors include risk-free interest rate, time to maturity, volatility of net present value, and options exercise price. Other than these factors, we are interested in the exogenous risks related to external uncertainties about technological cost, user learning and consulting, and so forth and we argue these risks should have a significant impact upon the volatility of net present value. To validate these factors empirically, we collected survey questionnaires from ERP project managers in Korea. We find that perceived exogenous risks with regard to ERP projects influence volatility and additionally find that ERP project managers prefer contract options of the project when the volatility of the project is expected to be high. We expect that this work will not only validate theoretical propositions but help project managers consider ERP options strategically based on these factors.

• 한국환경성돌연변이발암원학회지
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• 제24권3호
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• pp.137-142
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• 2004

Dioxin-like compounds are ubiquitous environmental polltants that could be accumulated in biological system and toxic to human and wildlife. Given this issue, it is important to develop a reliable dioxin detection methods for a rational risk assesment of dioxin-like compounds. In this study, we tried to set up and validate a sensitive, reliable risk assessment of dioxin-like compounds. In this study, we tried to set up and validate a sensitive, reliable and rapid bioassay model, CALUX bioassay as a screening tool for routine measurement of dioxin-like conpounds in environmental matrices. For the valisation of CALUX bioassay, firstly, we performed dose-response assay for 2,3,7,8-TCDD, most potent dioxin-like compound, using two different methods CALUX and EROD assay. Induction of luciferase activity and CYPIA catalyzed EROD activity were dose-dependently induced by 2,3,7,8-TCDD, with initial induction at 0.1 pM and maximal induction at 1 nM. In order t determine whether the CALUX bioassay could predict the effects of dioxin-like compounds, 2,3,7,8-TCDD dose-response from CALUX was compared with that from EROD assay. The correlation coefficient ($r^2$) was found to be 0.89, indicating a good correlation between two different methods and the possibility of CALUX bioassay as a useful dioxin detecting method.

• 센서학회지
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• 제25권4호
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• pp.297-301
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• 2016

ISO/IEC JTC1/SC29WG11 MPEG has been standardizing UD(user description) to give a user personalized recommendation services. Besides, CD(context description), service description(SD), and recommendation description(RD) are recently being standardized by UD Adhoc Group in MPEG with an advanced UD to cope with needs of current and upcoming services such as augmented reality and social network. The descriptions was reflected to MPEG-UD WD(Working Draft) at MPEG $107^{th}$ meeting and the document was finally approved as international standard by national bodies with standard number(ISO/IEC IS 21000-22 UD) at $114^{th}$ MPEG meeting. In addition, reference software WD to validate conformance of UD standard was approved at $113^{th}$ MPEG meeting. In this paper, we developed a demo program for visual communication according to guideline defined in reference software WD to validate the reference software as well as UD standard.

• 비파괴검사학회지
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• 제26권6호
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• pp.390-402
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• 2006

The elastic properties and thickness of mullite environmental barrier coatings grown through chemical vapor deposition (CVD) on silicon carbide substrates were measured using frequency domain photoacoustic microscopy. In this technique, extremely narrow bandwidth surface acoustic waves are generated with an amplitude modulated laser source. A photorefractive crystal based interferometer is used to detect the resulting surface displacement. The complex displacement field is mapped as a function of source-to-receiver distance in order to extract the wavelength of the surface acoustic wave at a given excitation frequency, and the phase velocity is determined. The coatings tested exhibited spatial variations in thickness and mechanical properties. The measured surface wave dispersion curves were used to extract an effective value for the elastic modulus and the coating thickness. Nanoindentation was used to validate the measurements of the effective elastic modulus. The average elastic modulus measured through the coating thickness using nanoindentation is compared to the effective modulus found using the photoacoustic system. Optical microscopy is used to validate the thickness measurements. The results indicate that the photoacoustic microscopy technique can be used to estimate the effective elastic properties in coatings exhibiting spatial inhomogeneities, potentially providing valuable feedback for the optimization of the CVD growth process.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제20권12호
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• pp.658-663
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• 2014

OpenStack과 같이 오픈 소스 기반의 클라우드 컴퓨팅 관리 플랫폼 (Cloud Management Platform) 의 빠른 구현으로 인하여, 오픈 소스를 이용한 개인 및 기관의 클라우드 구축 시도가 지속적으로 증가되는 추세이다. 이러한 클라우드 운영자들에게, 구축한 클라우드 컴퓨팅 시스템의 동작 검증은 필수적이다. 본 논문은 클라우드 시스템 구축 검증하기 위한 오픈 소스 기반의 클라우드 테스트 도구를 디자인하며 구현한다. 특히, 제안된 테스트 도구는 오픈 소스 소프트웨어 프로젝트인 Tempest를 활용하며, Tempest의 테스트 케이스를 통해서 OpenStack기반의 클라우드를 검증한다. 제안된 소프트웨어는 국내에서 처음으로 개발되는 클라우드 시스템 구축 테스트 도구의 프로토타입이며, 앞으로 클라우드 기술 개발 및 사용자 확대에 기여할 것으로 예상된다.

• Journal of Computing Science and Engineering
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• 제3권1호
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• pp.27-58
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• 2009

Aggregation join queries are an important class of queries over data streams. These queries involve both join and aggregation operations, with window-based joins followed by an aggregation on the join output. All existing research address join query optimization and aggregation query optimization as separate problems. We observe that, by putting them within the same scope of query optimization, more efficient query execution plans are possible through more versatile query transformations. The enabling idea is to perform aggregation before join so that the join execution time may be reduced. There has been some research done on such query transformations in relational databases, but none has been done in data streams. Doing it in data streams brings new challenges due to the incremental and continuous arrival of tuples. These challenges are addressed in this paper. Specifically, we first present a query processing model geared to facilitate query transformations and propose a query transformation rule specialized to work with streams. The rule is simple and yet covers all possible cases of transformation. Then we present a generic query processing algorithm that works with all alternative query execution plans possible with the transformation, and develop the cost formulas of the query execution plans. Based on the processing algorithm, we validate the rule theoretically by proving the equivalence of query execution plans. Finally, through extensive experiments, we validate the cost formulas and study the performances of alternative query execution plans.