• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3368-3372
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• 2012

The $Bi_2O_3$ nanowires are highly sensitive to low concentrations of $NO_2$ in ambient air and are almost insensitive to most other common gases. However, it still remains a challenge to enhance their sensing performance and detection limit. This study examined the influence of the encapsulation of ${\beta}-Bi_2O_3$ nanorods with $In_2O_3$ on the $NO_2$ gas sensing properties. ${\beta}-Bi_2O_3-core/In_2O_3-shell$ nanorods were fabricated by a two-step process comprising the thermal evaporation of $Bi_2O_3$ powders and sputter-deposition of $In_2O_3$. Multiple networked ${\beta}-Bi_2O_3-core/In_2O_3-shell$ nanorod sensors showed the responses of 12-156% at 1-5 ppm $NO_2$ at $300^{\circ}C$. These response values were 1.3-2.7 times larger than those of bare ${\beta}-Bi_2O_3$ nanorod sensors at 1-5 ppm $NO_2$. The enhancement in the response of ${\beta}-Bi_2O_3$ nanorods to $NO_2$ gas by the encapsulation by $In_2O_3$ can be accounted for based on the space-charge model.

• Structural Engineering and Mechanics
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• 제13권4호
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• pp.369-385
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• 2002

Ductility capacity is comprehensively studied for steel moment-resisting frames. Local, story and global ductility are being considered. An appropriate measure of global ductility is suggested. A time domain nonlinear seismic response algorithm is used to evaluate several definitions of ductility. It is observed that for one-story structures, resembling a single degree of freedom (SDOF) system, all definitions of global ductility seem to give reasonable values. However, for complex structures it may give unreasonable values. It indicates that using SDOF systems to estimate the ductility capacity may be a very crude approximation. For multi degree of freedom (MDOF) systems some definitions may not be appropriate, even though they are used in the profession. Results also indicate that the structural global ductility of 4, commonly used for moment-resisting steel frames, cannot be justified based on this study. The ductility of MDOF structural systems and the corresponding equivalent SDOF systems is studied. The global ductility values are very different for the two representations. The ductility reduction factor $F_{\mu}$ is also estimated. For a given frame, the values of the $F_{\mu}$ parameter significantly vary from one earthquake to another, even though the maximum deformation in terms of the interstory displacement is roughly the same for all earthquakes. This is because the $F_{\mu}$ values depend on the amount of dissipated energy, which in turn depends on the plastic mechanism, formed in the frames as well as on the loading, unloading and reloading process at plastic hinges. Based on the results of this study, the Newmark and Hall procedure to relate the ductility reduction factor and the ductility parameter cannot be justified. The reason for this is that SDOF systems were used to model real frames in these studies. Higher mode effects were neglected and energy dissipation was not explicitly considered. In addition, it is not possible to observe the formation of a collapse mechanism in the equivalent SDOF systems. Therefore, the ductility parameter and the force reduction factor should be estimated by using the MDOF representation.

• 생명과학회지
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• 제21권12호
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• pp.1721-1725
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• 2011

현재 전 세계적으로 알러지 질환은 급격히 증가하고 있는 추세이다. 기존의 길항제나 항원 특이적 면역 치료법의 부작용으로 인하여 항 알러지 작용에 효과적인 천연 기능성 물질에 대한 연구가 알러지 질환 치료의 유망한 분야로 여겨지고 있다. 비만세포는 히스타민이나 아라키돈 산, 그리고 전 염증성 사이토카인 등을 방출하는 알러지 반응에 주요하게 작용하는 효과세포이다. 우리는 참당귀의 뿌리로부터 추출한 노다케닌의 알러지 반응 억제효과에 대해서 연구하였다. 노다케닌을 이용하여 비만세포에서의 탈 과립현상 억제 효과를 측정한 결과, 비만세포에서 노다케닌이 탈과립의 표지인 ${\beta}$-hexosaminidase의 방출량을 농도 의존적으로 억제하는 것을 관찰하였고, 이러한 탈과립 억제 현상이 다양한 사이토카인 중 IL-4과 TNF-${\alpha}$의 양을 감소시킴으로써 매개된다는 사실을 RT-PCR을 통해 확인하였다. 또한 쥐에서 수동피부과민반응을 유도하여 노다케닌을 경구투여 했을 때 알러지성 과민반응 증상을 효과적으로 억제하는 것을 관찰하였다. 결과적으로, 이러한 결과들은 노다케닌이 항 알러지 약물의 개발에 잠재적인 후보물질이 될 수 있음을 시사한다.

• Molecules and Cells
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• 제38권12호
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• pp.1044-1053
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• 2015

This study first investigated the effects of corn gluten hydrolysate (CGH) (1.5 g/day) administration for 7 days on appetite-responsive genes in lean Sprague-Dawley (SD) rats. In a second set of experiments, the metabolic changes occurring at multiple time points over 8 weeks in response to CGH (35.33% wt/wt) were observed in high-fat (HF, 60% of energy as fat) diet-fed SD rats. In lean rats, the hypothalamus neuropeptide-Y and proopiomelanocortin mRNA levels of the CGH group were significantly changed in response to CGH administration. In the second part of the study, CGH treatment was found to reduce body weight and perirenal and epididymal fat weight. CGH also prevented an increase in food intake at 2 weeks and lowered plasma leptin and insulin levels in comparison with the HF group. This reduction in the plasma and hepatic lipid levels was followed by improved insulin resistance, and the beneficial metabolic effects of CGH were also partly related to increases in plasma adiponectin levels. The Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR), an index of insulin resistance, was markedly improved in the HF-CGH group compared with the HF group at 6 weeks. According to the microarray results, adipose tissue mRNA expression related to G-protein coupled receptor protein signaling pathway and sensory perception was significantly improved after 8 weeks of CGH administration. In conclusion, the present findings suggest that dietary CGH may be effective for improving hyperglycemia, dyslipidemia and insulin resistance in diet-induced obese rats as well as appetite control in lean rats.

• Earthquakes and Structures
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• 제2권4호
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• pp.357-376
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• 2011

Ground motion models predict the mean and standard deviation of the logarithm of spectral acceleration, as a function of predictor variables such as earthquake magnitude, distance and site condition. Such models have been developed for a variety of seismic environments throughout the world. Some calculations, such as the Conditional Mean Spectrum calculation, use this information but additionally require knowledge of correlation coefficients between logarithmic spectral acceleration values at multiple periods. Such correlation predictions have, to date, been developed primarily from data recorded in the Western United States from active shallow crustal earthquakes. This paper describes results from a study of spectral acceleration correlations from Japanese earthquake ground motion data that includes both crustal and subduction zone earthquakes. Comparisons are made between estimated correlations for Japanese response spectral ordinates and correlation estimates developed from Western United States ground motion data. The effect of ground motion model, earthquake source mechanism, seismic zone, site conditions, and source to site distance on estimated correlations is evaluated and discussed. Confidence intervals on these correlation estimates are introduced, to aid in identifying statistically significant differences in correlations among the factors considered. Observed general trends in correlation are similar to previous studies, with the exception of correlation of spectral accelerations between orthogonal components, which is seen to be higher here than previously observed. Some differences in correlations between earthquake source zones and earthquake mechanisms are observed, and so tables of correlations coefficients for each specific case are provided.

• 한국응용과학기술학회지
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• 제38권4호
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• pp.1020-1028
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• 2021

본 연구는 종합병원에서 근무하는 초보간호사의 임상수행능력에 영향을 주는 요인을 알아보고자 실시하였다. 초보간호사 155명을 대상으로 2020년 9월 11일부터 9월 30일까지 설문조사 하였으며, 수집된 자료는 SPSS 프로그램을 이용하여 t-test, ANOVA, Scheffe test, Person's correlation coefficients, 다중회귀분석을 하였다. 월경곤란증은 2.77점, 임상수행능력은 3.44점 이었고 월경곤란증과 임상수행능력은 유의한 음의 상관관계를 보였다(r=-.226, p=.002). 임상수행능력에 유의한 영향을 준 것은 자율신경계 반응이고(𝛽=-.261, p= .001) 설명력은 22.1%였다. 따라서 초보간호사의 임상수행능력을 증진시키기 위해 월경곤란증의 자율신경계 반응 완화를 위한 중재 교육 프로그램이 필요하다.

• 사상체질의학회지
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• 제35권1호
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• pp.35-45
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• 2023

Objectives We tried to examine the change in the test-retest response for the questionnaire itself regarding the QSCCII. Methods Tests were conducted twice times with an interval of 6 months between tests for test-retest reliability analysis. We examined the test-retest answer agreement rate (%) in all items of QSCCII . We conducted NcNemar analysis to examine test-retest reliability for 77 items selected from the QSCCII. Results The body shape-multiple-choice items showed a tendency of low test-retest agreement rate and most of the questions about when I was not well and when I felt my body condition improve showed an high test-retest agreement rate tendency in all items of QSCCII. As a result of the research on the selected 77 items, there was a significant change in the answer in item No.25, 58(in the item of Soeumin) item No.45, 103(in the item of Taeumin) and item No.87 (in the item of Soeumin) (Table.3, 4, 5, 6). Conclusion The QSCCII is shown as a questionnaire composed of mostly no significant response changes in test-retest in each item through this study. Some items were appropriately deleted in the process of developing the advanced model, but there are also items that should be considered further. It is thought that some items should be used after being refined in content and form.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.347-354
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• 2000

The seismic behaviors of a bridge system with several simple spans are examined to see the effects of the longitudinal stiffness degradation due to abutment-soil interaction. The abutment-backfill system is modeled as one degree-of-freedom-system with nonlinear spring and linear damper. various soil-conditions surrounding the abutment such as loose sand, medium dense sand, and dense sand are considered in the bridge seismic analysis. The idealized mechanical model for the whole bridge system is modeled by adopting the multiple-degree-of-freedom system, which can consider components such as pounding phenomena, friction at the movable supports, rotational and translational motions of foundations, and the nonlinear pier motions. The stiffness of the abutment is found to be rapidly reduced at the beginning of the earthquakes, and to be converged to constant values shortly after the displacement approaches to the Predefined critical values. It is observed that the maximum relative distanced an maximum relative displacements are generally Increased as the relative density of a soil decreases As the peak ground acceleration increases, the response ratio of the case considering stiffness degradation to the case considering constant stiffness decreases.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제22권1호
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• pp.29-62
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• 2018

We investigate a class of HIV infection models with two kinds of target cells: $CD4^+$ T cells and macrophages. We incorporate three distributed time delays into the models. Moreover, we consider the effect of humoral immunity on the dynamical behavior of the HIV. The viruses are produced from four types of infected cells: short-lived infected $CD4^+$T cells, long-lived chronically infected $CD4^+$T cells, short-lived infected macrophages and long-lived chronically infected macrophages. The drug efficacy is assumed to be different for the two types of target cells. The HIV-target incidence rate is given by bilinear and saturation functional response while, for the third model, both HIV-target incidence rate and neutralization rate of viruses are given by nonlinear general functions. We show that the solutions of the proposed models are nonnegative and ultimately bounded. We derive two threshold parameters which fully determine the positivity and stability of the three steady states of the models. Using Lyapunov functionals, we established the global stability of the steady states of the models. The theoretical results are confirmed by numerical simulations.

• 한국소음진동공학회논문집
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• 제19권4호
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• pp.347-354
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• 2009

Frequency analysis is one of the most useful way to analyze response signal for the purpose of grasping the dynamic characteristics of system through Fourier transformation. Although it is very effective way for frequency analysis, it is hard to analyze out a specific sound or vibration component which is correlated with others. In this thesis, source contribution analysis tool for NI-PXI equipment is developed with LabVIEW using coherences of MISO(multiple-input single-output) model. For the purpose of examining propriety of developed tool, simulation is performed with several correlated signals that have different frequency range. After checking the OCF(ordinary coherence function) and PCF(partial coherence function) of the each signal for concerned frequency domain, an experiment is conducted on an evaporator that cause the principal noise of a refrigerator. This developed tool will be expected to build up more convenient and serviceable measurement system.