• 한국세라믹학회지
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• 제32권12호
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• pp.1392-1400
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• 1995

WC-10wt%Co-Al2O3 ceramic composites, using both the SHS (Self-propagating High Temperature Synthesis) synthesized WC powder method and commercial WC powder, were prepared by varing WC-Co/Al2O3 vol% ratio and sintering temperature (1350℃∼1650℃) for 1 hr in Ar atmosphere. Mechanical characterization has been investigated by Instron meterial testing system and Vicker's hardness test. Compositional and structural chracterizations were carried out by energy-dispersive analysis of X-ray (EDAX) data and scanning electron microscope (SEM). Electrical characterization was carried out by the electrical resistivity measurement using 4-point probe method. As sintering period increased and Al2O3 contents decreased in WC-10wt%Co-Al2O3 ceramic composite, shrinkage and relative density increased, resulting in maximum values at 1600℃. Also the major matrix phase changed with increasing Al2O3 content from 0 to 100 vol%. It was also identified by SEM, EDAX, and electrical resistivity measurement. Based on the results of analysis of flexural strength, toughness and hardness, the mechanical properties of WC-10wt%Co-Al2O3 ceramic composites using the SHS synthesized WC powder were better than those WC-10wt%Co-Al2O3 ceramic composites using commercial WC powder because WC-10wt%Co-Al2O3 ceramic composites using the SHS synthesized WC powder were sintered very well due to small initial particle size. By the addition of 40 vol% Al2O3 [60(WC=10wt%Co)-40Al2O3], it was possible to obtain a proper candidate as a superalloy.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.113-120
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• 2001

A frame slab method has been proved as a possible and profitable construction solution for the urban tunnels with very shallow overburden and the excavation from the surface Is strictly limited. Since this method allows only a small amount of construction activities in the ground surface, the disturbances to the public and the surface traffic can be drastically reduced compared with the ordinary cut-and-cover method. The construction sequences of the method and the some of critical cautions needed are described in detail. Also a comprehensive numerical analysis including 2-D and 3-D analysis have been performed to verify the stability of the ground during the construction. It is revealed from this study that the frame slab method can be a quite successful solution for the shallow overburden tunnelling in urban area.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1243-1248
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• 2008

$CO_2$ emission amount and characteristics of combined heat and power (CHP) plant in industrial complex of Korea is evaluated by using the fuel analysis method. Fuel analysis methods of several foreign countries and developed one which is developed considering the operation characteristics of the surveyed CHP plants are used. The operation data is surveyed for all of the CHP plants in industrial complex and is composed of fuel consumption amount, generation, sale and efficiency of heat and electricity, condensed steam enthalpy, and etc of the each CHP.

• Genomics & Informatics
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• 제18권3호
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• pp.30.1-30.7
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• 2020

The novel coronavirus pandemic that has originated from China and spread throughout the world in three months. Genome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) predecessor, severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) play an important role in understanding the concept of genetic variation. In this paper, the genomic data accessed from National Center for Biotechnology Information (NCBI) through Molecular Evolutionary Genetic Analysis (MEGA) for statistical analysis. Firstly, the Bayesian information criterion (BIC) and Akaike information criterion (AICc) are used to evaluate the best substitution pattern. Secondly, the maximum likelihood method used to estimate of transition/transversions (R) through Kimura-2, Tamura-3, Hasegawa-Kishino-Yano, and Tamura-Nei nucleotide substitutions model. Thirdly and finally nucleotide frequencies computed based on genomic data of NCBI. The results indicate that general times reversible model has the lowest BIC and AICc score 347,394 and 347,287, respectively. The transition/transversions bias for nucleotide substitutions models varies from 0.56 to 0.59 in MEGA output. The average nitrogenous bases frequency of U, C, A, and G are 31.74, 19.48, 28.04, and 20.74, respectively in percentages. Overall the genomic data analysis of SARS-CoV-2, SARS-CoV, and MERS-CoV highlights the close genetic relationship.

• International Journal of Fluid Machinery and Systems
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• 제2권3호
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• pp.254-259
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• 2009

In this paper it was attempted to treat the hydrodynamic journal bearing as a time-based nonlinear reaction source in each step of rotor rotation in order to observe the bearing effect more realistically and accurately in stead of the conventional method of simple linearized stiffness and damping. Lubrication analysis based on finite element method is employed to calculate the hydrodynamic reaction of bearing and Newmark's method was used to calculate the rotor dynamics in the time domain. Simulation for an industrial electrical motor showed remarkable results with differences compared to those by the conventional method in the dynamic behavior of the rotor.

• 터널과지하공간
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• 제18권3호
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• pp.175-184
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• 2008

본 고에서는 온실가스 감축방안으로 배출 $CO_2$를 지하심부에 격리 저장시키는 지중 저장기술의 국내외 기술동향을 살펴보고 지반 및 암반공학적 관련기술로서 $CO_2$ 주입에 따른 대상지층의 역학적 안정성 및 누출경로 평가를 위한 열-수리-역학적 연계해석기술 및 적용사례, 기술개발요소를 소개하였다.

• 한국식품영양학회지
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• 제32권2호
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• pp.148-154
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• 2019

The aim of this study was to select compounds for the standardization of fermented Kalopanax pictus Nakai (KP-F), to develop the analysis method using HPLC-PDA and to perform method validation. KP-F is a fermented powder developed to improve the original physiological activities and create a new functionality. Eleutheroside E, Acanthoside B, and Syringaresinol were selected as the standard compounds and developed our own method for simultaneous analysis. The analyte was isolated using C18 column with a gradient elution of 0.05 M phosphoric acid in water and methanol as the mobile phase at a flow rate of 1 mL/min and detected at 210 nm. As a result, all standard compounds showed good linearity with an $R^2$ (coefficient of correlation) of 1.000 and for the limit of detection range of $0.710{\sim}0.831{\mu}g/mL$, and the limit of quantification as $2.150{\sim}2.520{\mu}g/mL$. The precision was RSD (%) of less than 4.80%, while the accuracy was 4.70%>RSD (%) for the range 102.44~110.48%. In conclusion, the developed analysis method is suitable for the detection of Eleutheroside E, Acanthoside B, and Syringaresinol in KP-F.

• 환경정책연구
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• 제12권3호
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• pp.97-122
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• 2013

우리나라의 1971년~2009년 시계열자료를 이용하여 소득 및 에너지소비와 $CO_2$ 배출량 간 동태적 관계를 분석한다. 자기시차분포(ARDL: Autoregressive Distributed Lag) 방법을 이용하여 소득 및 에너지소비와 $CO_2$ 배출량의 장 단기적 관계를 분석하고, Toda and Yamamoto 방법을 사용하여 주요 변수들 간 인과성을 분석한다. 추정 결과 에너지소비 및 소득과 $CO_2$ 배출량 간 장기균형관계가 존재하고 일시적 외생충격에 의해 불균형이 발생하더라도 빠르게 균형으로 회복되는 것으로 나타났다. 소득과 $CO_2$ 배출량은 장 단기적으로 N자형의 관계로 EKC 가설은 성립하지 않았다. $CO_2$ 배출량에 대한 에너지소비 장 단기탄력성은 양(+)이고, 에너지소비 장기탄력성이 단기탄력성보다 크게 나타났다. 인과성 측면에서 에너지소비량과 $CO_2$ 배출량은 쌍방향의 인과성이 존재하고, $CO_2$ 배출량 및 에너지소비는 소득에 일 방향의 인과성이 존재하는 반면에 그 역은 성립하지 않았다. 에너지소비가 직 간접적으로 소득보다 $CO_2$ 배출의 예측에 중요한 변수일 가능성을 제시한다.

• 약학회지
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• 제7권2_3호
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• pp.67-71
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• 1963

Studies the reaction mechanism and optimal reaction condition of the process of preparing sodium isocyanate, by means of heating of sodium carbonate and urea. Proposing, at the sametime, the quantitative analyzing method of sodium isocyanate in the presence of impurities of $Na_{2}CO_{3}$, urea and biuret. 1. Sodium isocyanate could be prepared by means of heating reaction of sodium carbonate and urea. 2. Adding urea into the heated sodium carbonate is reasonable. 3. Quantitative analysis of sodium isocyanate in the presence of impurities, $Na_{2}CO_{3}$, urea and biuret could be done by the following method:-adding nitrobarite solution into sample solution in order to remove $CO_{3}"$ and neutralize the solution, filtering off $BaCO_{3}$, and then precipitating isocyanate as a silver salt, filtering off AgNCO, and then, titrating remaining $AgNO_{3}$ with $NH_{4}SCN$, (indicator $FeNH_{4}(SO_{4})_{2})$/TEX>

• 대한기계학회논문집B
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• 제33권2호
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• pp.133-140
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• 2009

A fast-response $CO_2$ analyzer has been developed for measuring the $CO_2$ concentration during transient condition of a SI engine. The analyzer consists of the non-dispersive infrared absorption method, electrical chopping system and water cooling system. The analyzer has good repeatability, linearity and permissible drift characteristic. Besides, it showed 18ms of a response to measure the $CO_2$ concentration. The fast-response $CO_2$ analyzer was applied to a single cylinder SI engine and the $CO_2$ emission was examined during engine start. Simultaneously, the standard exhaust gas analyzer, which has slow response time, was used for confirming the accuracy of the exhaust gas analysis using the fast-response $CO_2$ analyzer. The developed analyzer showed much faster responsive characteristic than that of a standard analyzer and made cycle by cycle exhaust gas analysis possible. The transient engine operating characteristics will be estimated from the $CO_2$ concentration of engine-out emissions and engine operating variables.