• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.2
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• pp.21-30
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• 2000

Numerical design optimization techniques are implemented for the improvement of the ram accelerator performance. The design object is to find the minimum ram tube length required to accelerate projectile from initial velocity $V_o$ to target velocity $V_e$. The premixture is composed of $H_2$, $O_2$, $N_2$ and the mole numbers of these species are selected as design variables. The objective function and the constraints are linearized during the optimization process and gradient-based Simplex method and SLP(Sequential Linear Programming) have been employed. With the assumption of two dimensional inviscid flow for internal flow field, the analyses of the nonequilibrium chemical reactions for 8 steps 7 species have been performed. To determined the tube length, ram tube internal flow field is assumed to be in a quasi-steady state and the flow velocity is divided into several subregions with equal interval. Hence the thrust coefficients and accelerations for corresponding subregions are obtained and integrated for the whole velocity region. With the proposed design optimization techniques, the total ram tube length had been reduced 19% within 7 design iterations. This optimization procedure can be directly applied to the multi-stage, multi-premixture ram accelerator design optimization problems.

• Journal of the Korean Chemical Society
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• v.60 no.1
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• pp.59-68
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• 2016

The cultivation of scientific literacy in recent science education can be improved by experiencing and understanding scientific inquiry by which scientific knowledge is formed. The National Research Council(NRC) released the Next Generation Science Standards (NGSS) including 8 practices of science that help students experience scientists' inquiry and subdividing achievement standards to perform 8 practices of science into by grade clusters. This study was intended to examine science inquiry activities included in 4 high school chemistry II textbooks developed by the 2009 revised curriculum using the 8 scientific practices and their achievement standards for 9th-12th grade. The science inquiry activities and the science practices included in the 4 textbooks were 173 and 678. The science practices included in the inquiry activities of 4 textbooks included the most ‘analyzing and interpreting data.’ The ‘engaging in argument from evidence’, ‘Obtaining, Evaluating, and Communicating Information’ were less than other practices. The ‘asking questions and defining problem’ and ‘developing and using models’ were not nearly included in the 4 high school chemistry II textbooks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5C
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• pp.217-228
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• 2009

In case of application of electrophoresis method for leakage restoration of waste impoundment, main points of consideration were to evaluate the mobility of clay particles by electrophoretic force and capacity of leakage repair in leachate electrolyte system contained with various chemical species. However, the flocculation phenomena of clay particles induced by electrochemical interaction between various chemical species and clay particles would cause the big problems in electrophoresis method. Therefore, a series of laboratory tests such as one-dimensional electrophoresis and gravitational experiments were carried out in order to identify the specific chemical species affected flocculation of clay particles and the range of chemical concentration in leachate. In addition, the characteristics of clay particle behavior with chemical species and concentration range in leachate were analized using the concept of the settling velocity, zeta potential, and electrophoretic velocity.

• Proceedings of the Korean Society of Crop Science Conference
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• 1977.05a
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• pp.17.2-18
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• 1977

• Korean Journal of Head & Neck Oncology
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• v.11 no.1
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• pp.86-92
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• 1995

두경부 림프종은 두경부 림프절에 발생하는 호지킨씨병과 림프절외 림프종이 주종인 비호지킨 림프종 두종류가 있으며 이들 모두 완치율이 매우 높은 암종에 속하므로 병리학적 진단 후 정확한 병기분류를 위하여 권유되고 있는 검사들을 빠짐없이 실시하여야 된다. 조직학적 분류 및 병기가 결정된 후 내과종양의와 치료방사선의사 사이에 충분한 의 견교환을 거쳐 일차치료에 의한 근치를 유도키 위해 최선의 치료를 선택 실시함이 두경부 림프종 치료의 원칙이다.

• 대한두경부종양학회:학술대회논문집
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• 2001.05a
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• pp.89-89
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• 2001

• Economic and Environmental Geology
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• v.38 no.1
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• pp.23-31
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• 2005

This study was performed to investigate the effect of humic acid on the adsorption of arsenic onto hematite and its binding mechanism through the chemical speciation modeling in the binary system and the adsorption modeling in the ternary system. The complexation modeling of arsenic and humic acid was suitable for the binding model with the basis of the electrostatic repulsion and the effect of bridging metal. In comparison with the experimental adsorption data in the ternary system, the competitive adsorption model from the binary intrinsic equilibrium constants was consistent with the amount of arsenic adsorption. However, the additive rule showed the deviation of model in the opposite way of cationic heavy metals, because the reduced organic complexation of arsenic and the enhanced oxyanionic competition diminished the adsorption of arsenic. In terms of the reaction mechanism, the organic complex of arsenic, neutral As(III) and oxyanionic As(V) species were transported and adsorbed competitively to the hematite surface forming the inner-sphere complex in the presence of humic acid.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2008.11a
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• pp.336-337
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• 2008

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.16-475
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• 1998

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.35-36
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• 2008