• Journal of Ginseng Research
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• 제46권1호
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• pp.147-155
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• 2022

Background: Methamphetamine (METH) is the most widely used psychostimulant and has been known to exhibit reinforcing effects even after long abstinence. We showed the inhibitory effect of Korean Red Ginseng extract (RGE) on METH-induced addictive behaviors in animal models mimicking the human drug-use pattern. Methods: We first investigated the effect of RGE on the acquisition of METH-induced dependence using self-administration and conditioned place preference (CPP) tests. Additionally, further experiments such as METH-induced motivational behavior and seeking behavior were conducted. To study the underlying mechanism, dopamine receptor, dopamine transporter, and N-methyl-D-aspartate receptor were assessed through Western blot analysis. Results: Treatment with RGE significantly reduced METH-induced self-administration on a fixed-ratio 1 schedule of reinforcement. It could be also decreased a progressive ratio schedule, and inhibited METH-primed reinstatement. In CPP, RGE significantly prevented the development of METH-induced CPP. Moreover, RGE not only shortened the withdrawal period clearly, but also prevented the reinstatement of CPP. RGE treatment also reversed METH-induced overexpression of dopamine transporter, dopamine receptor D1, and NMDA receptor in the nucleus accumbens. Conclusion: Our findings reflect that RGE has therapeutic potential to suppress METH-induced addictive behaviors by regulating dopaminergic and NMDAergic system.

• 무역학회지
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• 제48권3호
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• pp.199-216
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• 2023

빠르게 성장하는 국경 간 전자상거래는 전통적인 무역과는 다른 특성을 보인다. 본 연구에서는 그중에서도 제품 유형이나 단가와 같은 품목 특성도 전자상거래 수출에 영향을 줄 수 있는지를 확인하였다. 이를 위해서 한국의 국가별, 품목별 전자상거래 수출 자료와 수출국의 특성 및 품목별 특성을 포함한 패널데이터를 구성하고, 이를 분석하였다. 연구결과 품목별 전자상거래 수출에도 거리의 영향 등이 유효하게 나타났으며, 계약 건별 금액, 내구소비재, 자본재와 같은 품목 특성도 전자상거래 수출에 영향을 미치는 것으로 나타났다. 이러한 연구는 국경 간 전자상거래의 특징에 대한 이해를 고취할 수 있을 것이며, 향후 품목별 데이터를 활용한 연구의 근거로도 활용할 수 있을 것이다.

• 한국과학교육학회지
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• 제27권5호
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• pp.412-420
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• 2007

이 연구에서는 인식론적 신념이 개념변화 과정에 미치는 영향을 인지갈등, 상황흥미, 주의집중, 상태 학습 전략을 고려하여 조사했다. 사전 검사로 인식론적 신념 검사를 실시한 후, 선개념 검사를 통해 밀도에 대한 특정 오개념을 지닌 중학교 1학년 218명을 선발했다. 변칙사례에 대한 반응 검사와 상황흥미 검사를 실시하고, CAI 프로그램을 통해 밀도 개념학습을 진행했다. 사후 검사로 주의집중, 상태 학습전략, 개념 검사를 실시했다. 연구 결과, 인식론적 선념의 요소인 고정된 능력, 빠른 학습, 확실한 지식들 사이에는 밀접한 관련성이 있었으나, 확실한 지식만이 개념이해에 직접적으로 부정적인 영향을 주었다. 이 영향력보다 상대적으로 영향력은 작았지만, 확실한 지식은 직접적으로 또는 상황흥미를 매개로 주의집중에 영향을 줌으로써 개념이해에 긍정적인 영향을 미치기도 했다. 그러나 인식론적 신념이 얀지갈등과 상태 학습전략을 통해 개념이해에 미치는 영향은 매우 작았다.

• Journal of Preventive Medicine and Public Health
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• 제33권3호
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• pp.343-348
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• 2000

Objectives : This study was conducted to integrate the results of studies assessing the association between chronic noise exposure and blood pressure. Methods : Using a MEDLINE search with noise exposure, blood pressure and hypertension as key words, we retrieved articles from the literature that were published from 1980 to December 1999. The criteria for quality evaluation were as follows: 1) the study subjects must have been workers employed at a high noise level area 2) The paper should use average and cumulative noise exposure as method for exposure evaluation. 3) Blood pressure in each article should be reported in a continuous scale Among the 77 retrieved articles, six studies were selected for quantitative meta-analysis. Before the integration of the regression coefficients for the association between blood pressure and noise level, homogeneity tests were conducted. Results : All studies were a cross-sectional design and the study subjects were industrial workers. Five papers used a time-weighted average for noise exposure and only one paper calculated the cumulative noise exposure level. The measurement of blood pressure in the majority of studios were accomplished in a resting stale, and used an average of two or more readings. The homogeneity of studies was rejected in a fixed effect model, so we used the results in a random effect model. The results of the quantitative meta-analysis, the weighted regression coefficient of noise associated with systolic blood pressure and diastolic blood pressure were 0.05 (95% confidence interval [CI]: -0.03, 0.13) and 0.06 (95% CI: -0.01, 0.13), respectively. Conclusions : Our results suggested that chronic exposure to industrial noise does not cause elevated blood pressure.

• 대한기계학회논문집
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• 제16권4호
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• pp.737-752
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• 1992

본 연구에서는 링크를 여러개의 2절점 6자유도의 보 요소로 이상화하고 링크 의 운동을 평면 운동으로 한정하며 링크의 지지부의 강성은 무한대이고 회전 대우 부 분의 간극은 없는 것으로 가정하여 링크의 탄성 변형에 관한 운동 반정식을 유도하였 다. 즉, 변위법에 기초한 정적 변위 해석에 관한 유한 요소법에서 관성력, 중력 그 리고 외력을 외부 부하로 간주하여 동적인 운동 방정식을 유도하였다. 여기에, 회전 대우의 베어링을 선형 스프링으로 이상화하여 유연성 링크의 일부분으로 고려함으로써 베어링의 탄성 변형이 유연성 링크의 동적 변형에 미치는 영향에 대하여 고찰하였다. 베어링의 탄성 변형이 고려된 유연성 링크에 관한 운동 방정식을 모우드 중첩법에 근 거를 둔 수치해법으로 그 해를 구하였다.

• Journal of Periodontal and Implant Science
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• 제46권6호
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• pp.382-395
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• 2016

Purpose: Alendronate has been proposed as a local and systemic drug treatment used as an adjunct to scaling and root planing (SRP) for the treatment of periodontitis. However, its effectiveness has yet to be conclusively established. The purpose of the present meta-analysis was to assess the effectiveness of SRP with alendronate on periodontitis compared to SRP alone. Methods: Five electronic databases were used by 2 independent reviewers to identify relevant articles from the earliest records up to September 2016. Randomized controlled trials (RCTs) comparing SRP with alendronate to SRP with placebo in the treatment of periodontitis were included. The outcome measures were changes in bone defect fill, probing depth (PD), and clinical attachment level (CAL) from baseline to 6 months. A fixed-effect or random-effect model was used to pool the extracted data, as appropriate. Mean differences (MDs) with 95% confidence intervals (CIs) were calculated. Heterogeneity was assessed using the Cochrane ${\chi}^2$ and $I^2$ tests. Results: After the selection process, 8 articles were included in the meta-analysis. Compared with SRP alone, the adjunctive mean benefits of locally delivered alendronate were 38.25% for bone defect fill increase (95% CI=33.05%-43.45%; P<0.001; $I^2=94.0%$), 2.29 mm for PD reduction (95% CI=2.07-2.52 mm; P<0.001; $I^2=0.0%$) and 1.92 mm for CAL gain (95% CI=1.55-2.30 mm; P<0.001; $I^2=66.0%$). In addition, systemically administered alendronate with SRP significantly reduced PD by 0.36 mm (95% CI=0.18-0.55 mm; P<0.001; $I^2=0.0%$) and increased CAL by 0.39 mm (95% CI=0.11-0.68 mm; P=0.006; $I^2=6.0%$). Conclusions: The collective evidence regarding the adjunctive use of alendronate locally and systemically with SRP indicates that the combined treatment can improve the efficacy of non-surgical periodontal therapy on increasing CAL and bone defect fill and reducing PD. However, precautions must be exercised in interpreting these results, and multicenter studies evaluating this specific application should be carried out.

• Asian Pacific Journal of Cancer Prevention
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• 제14권10호
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• pp.5761-5767
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• 2013

The potential correlation of X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln polymorphism with hepatocellular carcinoma (HCC) susceptibility is ambiguous. Taking account of inconsistent results of previous meta-analyses and new emerging literatures, we conducted a meta-analysis covering 15 case-control datasets to evaluate the relationship. Relevant studies from Medline, Embase and CNKI were retrieved. A fixed-effect model or a random-effect model, depending on between-study heterogeneity, were applied to estimate the association between XRCC1 polymorphism Arg399Gln and HCC risk with the results presented as odds ratios (ORs) and 95% confidence intervals (95% CIs). In accordance with Hardy-Weinberg equilibrium, 15 studies with data for 6,556 individuals were enrolled in this systematic review. For overall HCC,thr XRCC1 polymorphism Arg399Gln was significantly associated with HCC susceptibility in a homozygote model as well as in a dominant model (G/G vs. A/A, OR=1.253, p=0.028; G/G+A/G vs. A/A, OR= 1.281, p=0.047, respectively), but not in a heterozygote model (A/G vs. A/A, OR=1.271, p=0.066) or a recessive model (G/G vs. A/G + A/A, OR= 1.049, p=0.542). Similar results were also observed on stratification analysis by ethnicity (A/G vs. A/A, OR=1.357, p=0.025; G/G vs. A/A, OR=1.310, p=0.011; G/G+A/G vs. A/A, OR= 1.371, p=0.013). However, no potential contribution of XRCC1 Arg399Gln polymorphism to HCC susceptibility in HBV/HCV subgroups was identified. No publication bias was found in this study. In conclusion, the XRCC1 Arg399Gln polymorphism contributes to HCC susceptibility. Due to the lack of studies in Western countries, further large-sample and rigorous studies are needed to validate the findings.

• 한국해안·해양공학회논문집
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• 제27권5호
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• pp.339-344
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• 2015

석션기초는 해양분야의 기초 및 앵커로 널리 사용되고 있으며, 최근 들어 해상풍력발전기의 기초로도 그 활용 범위가 확대되고 있다. 많은 선행 연구로부터 기초구조물의 강성이 해상풍력발전기의 동적응답에 영향을 줄 수 있기 때문에 기초구조물에 대한 적절한 모델링이 필요한 것으로 입증된 바 있다. 본 논문에서는 3차원 유한요소 해석을 수행하여 석션기초의 강성행렬을 산정하였다. 이를 기존의 중력식 기초 강성 산정식에 의한 결과와 비교하였으며, 산정한 강성행렬을 적용하여 구조물의 동적응답과 고유진동수 검토를 위한 통합하중해석을 수행하였다. 해석결과 mudline에서 발생하는 하중에 대한 영향은 크지 않은 것으로 나타났지만, 기초를 고정단으로 모델링한 경우 고유진동수가 최대 약 10% 과대 예측하는 것으로 나타났다. 풍력발전기 공진 회피에 대한 검토 시 기초강성을 고려해야할 것으로 판단된다.

• Steel and Composite Structures
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• 제1권4호
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• pp.459-480
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• 2001

The damage suffered by steel structures during the Northridge (1994) and Kobe (1995) earthquakes indicates that the fully restrained (FR) connections in steel frames did not behave as expected. Consequently, researchers began studying other possibilities, including making the connections more flexible, to reduce the risk of damage from seismic loading. Recent experimental and analytical investigations pointed out that the seismic response of steel frames with partially restrained (PR) connections might be superior to that of similar frames with FR connections since the energy dissipation at PR connections could be significant. This beneficial effect has not yet been fully quantified analytically. Thus, the dissipation of energy at PR connections needs to be considered in analytical evaluations, in addition to the dissipation of energy due to viscous damping and at plastic hinges (if they form). An algorithm is developed and verified by the authors to estimate the nonlinear time-domain dynamic response of steel frames with PR connections. The verified algorithm is then used to quantify the major sources of energy dissipation and their effect on the overall structural response in terms of the maximum base shear and the maximum top displacement. The results indicate that the dissipation of energy at PR connections is comparable to that dissipated by viscous damping and at plastic hinges. In general, the maximum total base shear significantly increases with an increase in the connection stiffness. On the other hand, the maximum top lateral displacement $U_{max}$ does not always increase as the connection stiffness decreases. Energy dissipation is considerably influenced by the stiffness of a connection, defined in terms of the T ratio, i.e., the ratio of the moment the connection would have to carry according to beam line theory (Disque 1964) and the fixed end moment of the girder. A connection with a T ratio of at least 0.9 is considered to be fully restrained. The energy dissipation behavior may be quite different for a frame with FR connections with a T ratio of 1.0 compared to when the T ratio is 0.9. Thus, for nonlinear seismic analysis, a T ratio of at least 0.9 should not be considered to be an FR connection. The study quantitatively confirms the general observations made in experimental results for frames with PR connections. Proper consideration of the PR connection stiffness and other dynamic properties are essential to predict dynamic behavior, no matter how difficult the analysis procedure becomes. Any simplified approach may need to be calibrated using this type of detailed analytical study.

• Animal Bioscience
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• 제34권9호
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• pp.1499-1513
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• 2021

Objective: The purpose of this meta-analysis was to evaluate the effect of dietary essential oils (EOs) on productive performance, nutrient digestibility, and serum metabolite profiles of broiler chickens and to compare their effectiveness as growth-promoting additives against antibiotics. Methods: Peer-reviewed articles were retrieved from Web of Science, Science Direct, PubMed, and Google scholar and selected based on pre-determined criteria. A total of 41 articles containing 55 experiments with 163 treatment units were eligible for analyses. Data were subjected to a meta-analysis based on mixed model methodology considering the doses of EOs as fixed effects and the different studies as random effects. Results: Results showed a linear increase (p<0.001) on body weight gain (BWG) where Antibiotics (FCR) and average daily feed intake decreased (p<0.001) linearly with an increasing dose of EOs. Positive effects were observed on the increased (p<0.01) digestibility of dry matter, crude protein, ether extract, and cecal Lactobacillus while Escherichia coli (E. coli) population in the cecum decreased (p<0.001) linearly. There was a quadratic effect on the weight of gizzard (p<0.01), spleen (p<0.05), bursa of fabricius (p<0.001), and liver (p<0.10) while carcass, abdominal fat, and pancreas increased (p<0.01) linearly. The dose of EOs linearly increased high density lipoprotein, glucose, protein, and globulin concentrations (p<0.01). In comparison to control and antibiotics, all type of EOs significantly reduced (p<0.001) FCR and tended to increase (p<0.1) BWG and final body weight. Cinnamaldehyde-compound was the only EOs type showing a tendency to increase (p<0.1) carcass weight, albumin, and protein of serum metabolites while this EOs together with EOs-Blend 1 decreased (p<0.01) E. coli population. Low density lipoprotein concentration decreased (p<0.05) with antibiotics and carvacrol-based compound when compared to the control group. Conclusion: This evidence confirms that EOs are suitable to be used as growth promoters and their economical benefit appears to be promising.