• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.232-236
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• 2004

The fracture characteristics of unidirectional composite single-lap bonded joints were investigated experimentally and numerically. The effects of bonding method, surface roughness, bondline thickness and the existence of fillet on the failure characteristics and strength of bonded single-lap joints were evaluated experimentally. The failure process, failure mode and the behavior of load-displacement curve was apparently different according to bonding method. The failure load of the specimen co-cured without adhesive was definitely superior to other types of specimens but the specimens co-cured with adhesive film had a less strength than secondary bonded specimens. In the secondary bonded specimens, the lower value of surface roughness and existence of fillet improved the strength of specimens. The strain energy release rates calculated by geometric nonlinear finite element analyses and Virtual Crack Closure Technique for the secondary bonded specimens considering the three types of initial cracks - comer crack, edge crack and delamination crack - were consistent with the test results.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2010년도 추계학술발표대회
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• pp.1331-1334
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• 2010

공존 증명(Co-Existence Proof, CEP) 프로토콜은 둘 이상의 태그들이 공존했음을 증명하는 정보를 생성하는 것으로, 2004 년 A. Jules 가 제안한 이래 많은 연구가 진행되어 왔다. 하지만 대부분의 논문이 재전송 공격 방지와 익명화에 초점이 맞추어져 있다. 본 논문에서는 이러한 공존 증명 프로토콜을 인증 프로토콜, 검색프로토콜과 차별화 시킴과 동시에 현실적으로 공존 증명 프로토콜을 사용하고 연산량을 최소화 시킬 수 있는 환경에 대해 논한다.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.32-44
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• 2002

Selective catalytic reduction of nitric oxide by methane in the presence of excess oxygen was investigated over copper and cobalt ion-exchanged ZSM-5 zeolites. Copper ion-exchanged ZSM-5(Cu-ZSM-5) has the limitations for commercial applications to lean-bum gasoline and diesel engines due to low thermal stability and resistance to water vapor and sulfur dioxide. But cobalt ion-exchanged ESM-5(Co-ZSM-5) is more active at high temperatures and also stable to water vapor and sulfur dioxide for catalytic reduction of nitric oxide by methane. The catalytic activity of Cu-ZSM-5 for NO reduction increases with increasing temperatures, reaches the maximum conversion of 23.0% at 350\"C. and then decreases with higher temperatures. In the meantime catalytic activities of Co-ZSM-5 show the maximum conversion of 25.8% at $500^{\circ}C$ Therefore Co-ZSM-5 catalysts have higher thermal stability at high temperatures. Catalytic activities of both zeolites were remarkably enhanced with the existence of oxygen in the exhaust. It is noted that the catalytic activity of Cu-ZSM-5 decreases with the increasing concentration of methane while the catalytic activity of Co-ZSM-5 decreases with increasing contents of methane in the exhaust. This may imply the existence of different paths of NO reduction by methane in the presence of excess oxygen fur Cu-ZSM-5 and Co-ZSM-5 catalysts. For binary metal ionexchanged ZSM-5, the primary ion-exchanged metal may be masked by secondary ion-exchanged component, which plays the important role for catalytic activities of binary metal ion-exchanged ZSM-5, Therefore CuCo-ZSM-5 catalysts show the similar volcano-shaped curves to Cu-ZSM-5 catalysts between the activity and temperature. It Is interesting that the activities of CoCu-ZSM-5 catalysts indicate almost no dependence on the concentration of methane in the exhaust.aust.

• Nonlinear Functional Analysis and Applications
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• 제28권2호
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• pp.497-520
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• 2023

Numerous problems in science and engineering defined by nonlinear functional equations can be solved by reducing them to an equivalent fixed point problem. Fixed point theory provides essential tools for solving problems arising in various branches of mathematical analysis, such as split feasibility problems, variational inequality problems, nonlinear optimization problems, equilibrium problems, complementarity problems, selection and matching problems, and problems of proving the existence of solution of integral and differential equations.The theory of fixed is known to find its applications in many fields of science and technology. For instance, the whole world has been profoundly impacted by the novel Coronavirus since 2019 and it is imperative to depict the spread of the coronavirus. Panda et al. [24] applied fractional derivatives to improve the 2019-nCoV/SARS-CoV-2 models, and by means of fixed point theory, existence and uniqueness of solutions of the models were proved. For more information on applications of fixed point theory to real life problems, authors should (see [6, 13, 24] and the references contained in).

• 한국환경보건학회지
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• 제22권4호
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• pp.16-24
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• 1996

This study was performed to investigate the effect of co-existence of carbaryl and chlorothalonil on the short-term bioconcentration factor in Carassius auratus(goldfish). The fishes were exposed to the combined treatment of carbaryl and chlorothalonil(0.05 ppm+0.005 ppm, 0.05 ppm+0.010 ppm, 0.10 ppm+0.005 ppm) for 1, 3 and 5 days, respectively. Carbaryl and chlorothalonil in fish and in test water were extracted with n-hexane and acetonitrile. GC-ECD was used to detect and quantitate carbaryl and chlorothalonil. 1-day, 3-day and 5-day bioconcentration factors($BCF_1, BCF_3$ and $BCF_5$) of each pesticide were calculated from the quantitation results. The depuration rate of each pesticide from the whole body of fish was determined over the 72-h period after combined treatment. The results were as follows: $BCF_1$ values of carbaryl were 3.521, 3.802 and 3.587, respectively, when the concentration of carbaryl and chlorothalonil in combined treatment were 0.05+0.005, 0.05+0.010 and 0.10+0.005 ppm. BCF3 values of carbaryl were 4.825, 4.556 and 3.828, respectively, and $BCF_5$ values of carbaryl were 3.974, 3.921 and 4.186, respectively, under the conditions. While $BCF_1$ of chlorothalonil were 0.829, 0.829 and 1.540, respectively, under the same condition of pesticide concentrations $BCF_3$ of chlorothalonil were 2.040, 2.208 and 3.633, respectively, and $BCF_5$ of chlorothalonil were 6.222, 6.667 and 7.095, respectively, under the conditions. Depuration rate constants of carbaryl were 0.022, 0.022 and 0.152, respectively, when the concentration of carbaryl and chlorothalonil in combined treatment were 0.05+0.005, 0.05+0.010 and 0.10+0.005 ppm. While depuration rate constants of chlorothalonil were 0.004, 0.004 and 0.006, respectively, under the same condition of pesticide concentrations. It was observed that no significant differences of carbaryl and chlorothalonil concentration in fish extracts, test water and $BCF_s$ of carbaryl and chlorothalonil between combined treatment and single treatment. It was considered that no appreciable interaction at experimental concentrations was due to low concentrations, 0.005~0.1 ppm. Co-existence of carbaryl and chlorothalonil had no effect on excretion of each pesticide and depuration rate of chlorothalonil was investigated 1/8 slower than that of carbaryl in combined treatment. Therefore, it is considered that the persistence of chlorothalonil in fish body would be higher than that of carbaryl.

• 경영과학
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• 제29권3호
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• pp.169-182
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• 2012

This study examines the co-evolutionary process between open innovation and firms' absorptive capacity. The effects of open innovation can be maximized through the capacity to absorb the knowledge from the external sources such as universities, government-support research institute, and private R&D centers. This study used data of STEPI technology innovation survey conducted at 2002, 2005, and 2008 (3 points measures). The data were analyzed through a structural equation model. Results suggest that open innovation at t0 point influences positively the absorptive capacity at t1 point, which subsequently enhances the intention of open innovation at t2 point. This result suggests the existence of co-evolutionary process between open innovation and firms' absorptive capacity. When knowledge comes from universities, the co-evolution has sustained; whereas when knowledge comes from private firms' R&D centers, the co-evolution has not effected. Theoretical and practical implications are discussed.

• KIEAE Journal
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• 제7권4호
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• pp.39-44
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• 2007

The purpose of this research is to study security of $CO_2$ exhaust at night in indoor air quality purifying system using plants. For this purpose, two same units for experiment were built, and difference of $CO_2$ exhaust by existence and nonexistence of plantation were measured. To reduce error by entrance of people, automatic measurement system were developed and used. At first, baseline were measured to check standard value, and next, $CO_2$ exhaust by plantation were measured. As a result, in baseline experiment, values of all spaces were steady as 400~500 ppm. When plantation was set-up, value of $CO_2$ at night was measured high as 150 ppm, and maximum value was around 600 ppm. This result is a lot lower than maximum standard of $CO_2$, 1000 ppm.

• Asian Journal of Atmospheric Environment
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• 제12권1호
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• pp.30-36
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• 2018

This study investigates the relationship between economic growth, energy consumption, trade openness, population density, and carbon dioxide ($CO_2$) emissions in Bangladesh for the period of 1975 to 2013. It applies the Autoregressive Distributed Lag (ARDL) bounds testing approach to cointegration for establishing the existence of a long-run relationship. The bounds tests suggest that the variables of interest are bound together in the long-run when $CO_2$ emissions is the dependent variable. The results indicate that energy consumption has statistically significant positive effect on $CO_2$ emissions both in the short-run and long-run. The effect of population density is significant in long-run, but not in short-run. The estimated coefficients for economic growth and trade liberalization are negative and insignificant both in short-run and long-run. The paper suggests that the government of Bangladesh should undertake the policy actions to develop alternative energy sources which would not emit much $CO_2$.

• 한국토양비료학회지
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• 제36권5호
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• pp.263-271
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• 2003

$CO_2$ 가스 존재여부와 pH가 Pb(II)와 sodium dodecyl sulfonate(SDS, $C_{12}H_{25}SO_3Na$) 흡착에 따른 silca 표면의 특성 변화에 미치는 영향을 contact angle 과 AFM을 이용한 힘 측정을 통하여 살펴보았다. 대기와 접촉하여 $CO_2$가 용해되는 조건에서 Pb와 SDS가 $10^{-4}M$ 씩 들어 있는 혼합용액을 처리하였을 때, fused silica 표면의 contact angle은 $PbCO_3$의 침전 때문에 최대 $46^{\circ}$로 낮았다. 반면에 $N_2$ 개스를 불어넣는 $CO_2$ 부재조건에서는 $PbCO_3$의 침전이 없었기 때문에 contact angle이 최대 $90^{\circ}$로 크게 증가되었다. $CO_2$ 부재조건에서 pH에 따른 contact angle과 AFM에서 측정한 점착력($F_{ad}$) 변화 양상은 $PbOH^+$ 화학종 분포와 유사하였으므로, Pb(II)의 silica 표면 흡착형태는 $PbOH^+$ 로 판단되었다. 한편 contact angle 과 AFM 측정결과 모두 Pb 단독처리에서 소수성을 발현하였다. 이 결과는 현재까지의 알려진 이론으로 설명할 수 없었으며 이를 위하여 원자수준에서의 심도 깊은 연구가 필요하다고 판단되었다.

• Fibers and Polymers
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• 제6권4호
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• pp.284-288
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• 2005

Poly(ethylene terephthalate) was annealed at different temperature and pressure of supercritical carbon dioxide $(CO_2)$ using samples quenched from the melt. Crystallization and molecular relaxation behavior due to $CO_2-annealing$ of samples were investigated using differential scanning calorimetric and dynamic mechanical measurements. The glass transition and crystallization temperatures significantly decreased with increasing temperature and pressure of $CO_2$. The dynamic mechanical measurement of samples annealed at $150^{\circ}C$ in supercritical $CO_2$ showed three relaxation peaks, corresponding to existence of different amorphous regimes such as rigid, intermediate, and mobile domains. As a result, the mobile chains were likely to facilitate crystallization in supercritical state. It also led to the decreased modulus of $CO_2-annealed$ samples with increasing pressure.