• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4D
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• pp.571-576
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• 2011

In general, conventional road pavements are designed under the assumption that the shear strength of geomaterials are under saturated state. In reality, however, most of the pavement geomaterials exists under the unsaturated state. To deal with this gap between saturated and unsaturated conditions, in this paper, unsaturated shear strength was estimated using the results from the triaxial compression test and soil-water characteristics curves. Then, yield loads were assessed using 2-Dimensional finite element method with the selected nonlinear elastic model and the Mohr-Coulomb yield criteria. In addition, various unsaturated condition and surface layer effects on the yield load of granular materials were identified. Therefore, the results demonstrated would provide a possibility to estimate bearing capacity of paved or unpaved roads using unsaturated soil mechanics.

• Journal of Korea Technology Innovation Society
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• v.16 no.4
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• pp.937-953
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• 2013

The theoretical discussion of generation process and development directions of economic fluctuations are actively discussed. This study describes the economic changes applied to empirical research on economic volatility in Korea under the economic theory of network theory [Acemoglu, et al. 2012, 2010]. For the three years in 2000, 2005, and 2010, the network analysis were applied to industry input-output tables. The research results show that the network economic structures in Korea is shifted from a high connectivity among sectors to a lower connectivity. Also, the impact of key industries and the mutual connectivity of input and out among industrial sectors are weaken. Implications for industry and technology policy are derived form the study results.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.1-8
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• 2013

In this study, 120 cases of damage due to ground subsidence of city gas pipeline which is hanging on apartment outer wall were investigated. From the survey results, it was determined to be approximately 100m~200mm ground subsidence occurred and at severe damage, pipeline was cut and the gap was about 50mm between two cut pipeline. Device for measuring the amount of deformation of standing gas pipeline was designed and fabricated. And installed it on apartment outer wall for measuring the deformation due to ground subsidence, after 5 months measurement the amount of ground subsidence was measured to 1.3mm. Stress assessment was conducted based on results of ground subsidence occurred on standing gas pipeline.

• 한국정보교육학회:학술대회논문집
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• 2004.08a
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• pp.397-405
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• 2004

선진 각국에서는 지식기반 정보사회로의 급속한 이행과 사이버 공간의 확장에 따라 사이버 교육에 대한 법적 제도적 근거를 마련함은 물론 이의 적극적인 활용을 모색하고 있다. 우리나라에서는 교육혁신과 인적자원개발을 위한 2단계 교육정보화종합발전 방안을 마련 및 교육과정의 개편, 실행에 옳기고 있다. 새로운 이론인 구성주의에 근거 마련된 제7차 교육과정에서는 교수 학습시 ICT의 활용을 적극 권장하는 바, 훈련 받은 교사에 의한 아동의 교수 학습 효과가 현저하여 교사의 ICT활용 관련 기회의 요청이 요구되고 있다 본 연구에서는 전국규모의 교육용소프트웨어 공모전에 참여하는 경북지역 교사들의 ICT 활용 능력과 학교급별, 지역별, 저작도구별, 분과, 분야별, 저작인수별 실태를 파악하기 위하여 당해연도 경북도 대회 2등급 이상 상위 입상작 48편에 대한 분석 및 고찰을 실시한 결과, 교원의 ICT활용 능력 신장, 지역간 정보격차 해소, 교수 학습 방법 개선 지원을 강화할 필요가 있는 등 다수의 유의미한 결과를 얻었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.69-78
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• 1993

A testing system has been developed to evaluate the seasonal variation of the resilient modulus of granular subgrade soils. Two sites were successfully instrumented with soil moisture-temperature cells to monitor over a period of one year, the field temperature and moisture content underneath the pavement. Multiple regression equations were developed to determine the resilient modulus under environmental conditions. It is noted that the use of the effective resilient modulus at the location of the Average Depth of Significant Stress (ADSS) provides a reasonable basis for determining subgrade properties. In addition, a theoretical model has been developed to predict the resilient modulus due to the change of temperature and moisture condition.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1087-1093
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• 2010

Autotrophic denitrification is known as an effective and economical alternative for heterotrophic denitrification using external carbon sources such as methanol. In this study, we evaluated design and operation parameters for a sulfur denitrification reactor (SDR) treating high strength nitrogen wastewater. The SDR was filled with spherical sulfur media in connected to a pilot-scale nutrient removal process (daily flow rate, $Q=18\;m^3/d$) using moving spongy media. Total nitrogen (TN) concentration of the final effluent was below the 7.0 mg TN/L because nitrate was additionally removed through autotrophic denitrificationin without adding alkalinity (initial alkalinity was $169.4{\pm}20.8\;mg$ $CaCO_3$/L). During the test period, 60~80% of nitrogen in the influent was removed even in low temperature (below $15^{\circ}C$). The alkalinity consumption for nitrate removal in SDR was $4.09{\pm}1.29$ g $CaCO_3/g$ ${NO_3}^-$-N, and the residual alkalinity of influent of SDR was higher than that of theoretical requirements for full conversion of nitrate. The consumption of sulfur was 943.8 g S/d and it was 2.4 times higher than theoretical value (400.1 g S/d) due to abrasion and loss of sulfur media in backwash, etc.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.99-107
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• 2004

Anisotropic characteristics of deformation are important to understand the particular behavior in the pre-failure state of soils. Recent experiments show that cross-anisotropic moduli of granular soils can be expressed by functions of normal stresses in the corresponding directions, which is closely linked to micromechanical characteristics of particles. Granular soils are composed of a number of particles so that the force-displacement relationship at each contact point governs the macroscopic stress-strain relationship. Therefore, the micromechanical approach in which the deformation of granular soils is regarded as a mutual interaction between particle contacts is one of the best ways to investigate the anisotropic elastic deformation of soils. In this study, a numerical program based on the theory of micromechanics is developed. Generalized contact model for the irregular contact surface of soil particles is adopted to represent the force-displacement relationship in each contact point far the realistic prediction of anisotropic moduli. To evaluate the model parameters, a set of analytical solutions of anisotropic elastic moduli is derived in the isotropic stress condition. A detailed procedure to determine the model parameters is proposed with emphasis on the practical applicability of micromechanical program to analyze the elastic behavior of the granular soils.

• Journal of The Korean Association For Science Education
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• v.18 no.4
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• pp.627-633
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• 1998

Achievements of Korean delegate students who attend on the 9th International Biology Olympiad(IBO) were compared with those of IBO participants for the 4th, 5th and 7th theoretical tests. It was predicted that four Korean delegates won medals in the 9th IBO on the basis of the average percentages of correct answer and the shifting patterns of achievement. And achievemens of four delegates during delegates training period were compared with that in the 9th IBO. Mean perecntages of theoretical part of them were 78.15%, 77.16%, 80.97% and 76.99% respectively, and total mean percentage was 78.32%. Their achievement was level for silver medalist. It was 86.56% on the average that they had achieved in the 9th IBO. This result was more than achievement in delegates training. Their percentages of achievement order were 90.84%, 97.71%, 82.44% and 70.99% respectively. One of them won gold medal and the others won silver medals. It was needed to develop effective teaching program for biology gifted-students and training preparing for IBO.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.788-794
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• 1985

A study on the number density in a dual beam LDV is carried out with moving particles of various irregular arrangements. Ratious of the particle diameter to the particle to the fringe Spacing are D/.delta. = 0.3, 0.5, 1.0 and 1.5. In the case of the small number of moving particles(N<10), the visibility is influenced much by the difference of the phase of particles for one side fringe and the change in visibility is shown remarkable. In the case of the larger number of particles, the decreasing rate for visibility on the graph is smooth because the effect of the phase difference of particles is decreased by more unitorm distribution of particles over fringes. And the formula of the number density on the basis of probability is fairly compared with experimental values.

• The Journal of the Korea Contents Association
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• v.12 no.7
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• pp.76-85
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• 2012

Early photography history of Daegu, Gyeongbuk Province, Gyebok Choi were taken a lots of prizes of famous contest and known to the nationwide in 1930's and then his photos became an example of salon photography. And his documents of Mt. Baekdu & Dokdo in 1940's was the outcome of self-consciousness. Wangsam Koo proposed the realism of the photo. He saw, the base of photos should be reflected the lives of people of the times and the characteristics of the period, and he had great influence to the history of Korea photography with his own unique vision. These photos and theories accomplished a photo aesthetic to Korea photo history in 1940's. Besides it had been the national spirit at Youngnam province in the early 20th century.