• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.447-453
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• 2010

The purpose of this study was to compare the light transmitting ability of halogen light in different colors and thicknesses. A1, A2, A3 colors of Z-250 composite resin(3M ESPE, St. Paul, U.S.A.) were used. Degree of conversion of separated resin specimens under the 2, 3, 4mm thickness resin were measured by FTIR spectroscopy. The result shows that decrease of degree of conversion by increase of resin thickness and decrease of degree of conversion by decrease of lightness of color. Within the limitation of results, it is recommended to use more light color of composite resin in small thickness to improve degree of conversion when use halogen light.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.525-533
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• 1997

Background : No ideal combination chemotherapy for lung cancer has been established even though lots of combination anticancer chemotherapies have been tried. For the combination of anticancer drugs, the interaction of anticancer drugs is very important but unpredictable factor. In this experiment, we designed and tested new experiment to measure the interaction of two anticancer drugs using MIT assay in an attempt to predict clinical response of the combination regimen. Methods : With human lung adenocarcinoma cell line (PC-14), the cytotoxic effect of cisplatin, adriamycin, mitomycin C and etoposide were measured by in vitro chemosensitivity test (MIT assay). The combined cytotoxic effects of combination of two drugs were also measured in every combination of the drug concentrations and analyzed the interaction by Anava analysis of two way factorial design. Results : Four individual drugs showed cytotoxic effects on PC-14 by dose dependent fashion. Comparison of two drug combinations revealed that mitomycin C + cisplatin and adriamycin + cisplatin combinations showed stronger synergistic cytotoxic effects. Conclusion : From this experiment, we suggest two combinations of mitomycin C + cisplatin and adriamycin + cisplatin as chemotherapeutic regimens for unresectable non-small cell lung cancer. Furthermore, this experimental design could be applied to other types of cancer requiring combination anticancer chemotherapy.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.675-682
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• 2002

The beam of composite structure composed of the RC structure in the end part and steel structure in the central palt were investigated during cyclic loading, in order to evaluate strength, stiffness, and deformational capacity. The parameters used in this study include the amount of reinforced steel bar between the steel beam and RC structure and the existence of the sticking plate. Test results showed that all specimens had stabilized hysteresis loops. Likewise, the specimens with sticking plate had higher load-carrying capacity compared with the one without it. In addition, the stiffness of the composite structure was higher than the steel structure. All specimens also showed good rotational capacity.

• Composites Research
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• v.13 no.3
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• pp.9-20
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• 2000

Free vibration characteristics of a cantilevered laminated composite beam with multiple non-propagating transverse open cracks are investigated. In the present analysis a special ply-angle distribution referred to as asymmetric stiffness configuration inducing the elastic coupling between chord-wise bending and extension is considered. The multiple open cracks are modelled as equivalent rotational springs whose spring constants are calculated based on the fracture mechanics of composite material structures. Governing equations of a composite beam with open cracks are derived via Hamilton's Principle and Timoshenko beam theory encompassing transverse shear and rotary inertia effect is adopted. The effects of various parameters such as the ply angle, fiber volume fraction, crack numbers, crack positions and crack depthes on the free vibration characteristics of the beam with multiple cracks are highlighted. The numerical results show that the existence of the multiple cracks in an anisotropic composite beam affects the free vibration characteristics in a more complex fashion compared with the beam with a single crack.

• Polymer(Korea)
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• v.34 no.4
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• pp.326-332
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• 2010

Nanocomposite films were prepared by blending poly(amic acid)(PAA), poly(o-hydroxyamide)( PHA) and organically modified montmorillonite (OMMT) that has a layered structure. XRD, SEM and TEM were used to study the morphology of PAA/PHA nanocomposites, and DMA, TGA, UTM, LOI and PCFC techniques were used to characterize the mechanical and thermal properties, and flame retardancy of the nanocomposites. TEM images revealed that OMMT layers were well dispersed in the PAA/PHA matrix and showed exfoliation and intercalation behavior. The addition of 3 wt% OMMT to the PAA/PHA blend increased the initial modulus of PAA/ PHA blend to 3.68 GPa that was ca. 48% higher than that of the control PAA/PHA blend. Above 4 wt%, however, both the initial modulus and the tensile strength were found to decrease, which might be due to the aggregation of OMMT in PAA/PHA matrix. When the OMMT content was below 3 wt%, the thermal stability and flame retardancy of the PAA/PHA nanocomposites increased with increasing OMMT content.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.272-276
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• 2011

현재 우리나라에서 사용되고 있는 강우-유출모형은 하도추적 방식을 모형 내에 내장되어 있는 해석절차나 유역내 모든 관거 및 하도에 일괄하여 적용하는 방식으로 되어있어 도시유역과 같이 관거와 하도가 복합적으로 구성되어 있는 경우 적절한 해석방식의 채택이 힘든 실정이다. 따라서 본 연구에서는 관거 및 하도의 개별적인 해석이 가능한 2009년 하천설계기준의 도시유역 유출해석 모형으로 포함된 FFC2Q모형을 이용하여 관거와 하도가 복합적으로 구성되어 있는 홍제천 유역을 선정하여 흐름이송 해석방법을 다양하게 설정하여 강우-유출 특성을 분석하고 실측자료에 대한 모의 방식별 분석결과에 대한 적합도를 분석하였다. 적합도 분석결과 하도에 Muskingum-Cunge법, 관거에 Kinematic-Wave법을 적용하여 흐름이송해석을 하는 경우가 가장 적합한 것으로 나타났다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.375-380
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• 1997

모의 방사성 세탁폐액을 제조하여 오존에 의한 세제 파괴를 확인하고 활성탄 및 이온교환수지를 이용하여 세제 및 Co, Cs 제거율을 조사하였으며 모의 방사성 세탁폐액을 오존으로 부분적으로 산화ㆍ파괴시킨후 활성탄 및 이온교환수지에 의한 흡착 및 이온교환 실험을 수행하여 오존의 세제 파괴가 방사성 물질 제거에 미치는 영향을 조사하였다. 오존에 의해 세제는 75% 정도 제거될 수 있었고 활성탄으로 방사성 모의세탁폐액을 처리할 때 세제농도가 증가하면 방사성 핵종 제거율이 감소하였다. 이온교환수지로 세제를 제거할 때 성취가능 제거율은 Co의 경우 99% 이상이었으며, 세제 존재시 방사성 Co 및 Cs 제거율은 감소하며, 방사성 모의세탁폐액을 오존으로 조사후 활성탄과 이온교환수지로 방사성 핵종을 제거할 때 그 제거율은 거의 변화가 없었다. 이상과 같은 실험 결과로부터 오존으로 부분적으로 산화시켜 활성탄의 세제 제거효율을 최대화하고, 역삼투막에 의한 방사성 핵종을 제거하며 이온교환수지로 잔류 방사성 핵종을 완전히 처리할 수 있는 복합 공정을 도출하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.4
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• pp.40-49
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• 2001

The basic research on AKM(Apogee Kick Motor) for space launch vehicle was carried out. AKM which will be used as 3rd stage solid rocket motor in 3-stage Korean Sounding Rocket(III) has been developing. KM is a solid rocket motor using composite propellant based on HTPB and is composed of composite motor case and submerged nozzle. To develop KM rocket motor satisfing a given set of requirement, firstly the full-scale KM with diameter 520mm was designed, then sub-scale motors reduced about 60% were manufactured and tested. Full-scale ground firing test is accomplished two times.

• Journal of the Korean Data and Information Science Society
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• v.23 no.4
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• pp.787-796
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• 2012

The aim of this study is to closely examine the changes in their metabolic syndrome index and autonomic nerve systems after the 16-weeks's combined exercise program is carried out on low-level physical strength group (PAPS 4-5 level students). They were divided into two groups; exercise training group (15) and control group (15). This program consisted of five-times-a-week's warm-ups, main activities and warm-downs and it takes 50 minutes per trial. Through SPSS 19.0, all averages and standard deviations of dependent variables were calculated. We first performed Shapiro-Wilk's normality test of the variables. Before verifying the effect of combined exercise program, we tested the equality of means of the variables between combined-exercise-programmed-group and control group through a two-sample t-test and carried out a paired t-test to check if the changes in the variables of two groups before and after 16 weeks are statistically significant. Every statistical test is performed at a significance level of ${\alpha}$=.05. The results are as follows. When it came to metabolic syndrome index, there were statistically meaningful changes in waist measurement, triglyceride, glucose with empty stomach and HDL-C. Also, when it came to autonomic nerve system, there were meaningful changes in all variables. Consequently, it seems that the 16-weeks combined exercise program has positive effects on low level physical strength students.

• Journal of Wetlands Research
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• v.24 no.2
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• pp.69-82
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• 2022

In this study, we investigated the bacterial community structure in organic rice-fish mixed farming paddy soil by using high-throughput sequencing technology. The results showed that compared with the organic rice cultivated soil, the content of AP (available phosphorus) increased by 310.23 % and the content of OM (organic matter) increased by 168.83%. The most abundant phyla in paddy soils were Proteobacteria, Bacteriodetes, and Chloroflexi, whose relative abundance was above 47.83%. Among the dominant genera, the relative abundance of Limisphaera in paddy soils was observed. Alpha diversity indicated that the bacterial diversity of paddy soils was similar among each other. The bacterial community structure was affected by the relative abundance of bacteria, not the species of bacteria. Principal Coordinated Analysis (PCoA) results showed that the bacterial communities in organic rice-fish mixed farming soil and organic paddy soil were correlated to each other; the bacterial community structure was distinctively grouped by four different systems (paddy soil under organic rice-fish mixed farming system, organic rice cultivation, and conventional rice cultivation), where the first two are closely related to each other than the third one. The results provide basal support for organic agri-cultivation while improving an ecological value at the same time.