• 화훼연구
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• 제17권3호
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• pp.147-151
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• 2009

본 실험은 스탠다드국화 'Baekma'품종의 줄기공동에 의한 줄기 부러짐을 방지하기 위하여 수행하였다. 'Baekma' 품종의 줄기공동은 초장이 20 cm정도 되었을 때부터 시작되어 지제부로부터 5 cm 사이에서는 공동화가 상당히 진전되어 있었고, 이 후 발뢰를 하여 초장이 80 cm 정도 되는 생육 후반기에는 상부 20 cm만 남기고 모두 공동이 발생하였다. 절회장과 경경, 꽃목길이는 정식거리 $11cm{\times}11cm$에서 가장 좋았고, 수광량은 정식거리 $9cm{\times}9cm$ 대비 정식거리가 $10cm{\times}10cm$, $11cm{\times}11cm$, $12cm{\times}12cm$로 넓어질수록 각각 47, 99, 143% 증가하였다. 줄기의 경도와 강도는 정식거리 $11cm{\times}11cm$에서 줄기강도 $567kgcm^{-2}$, 경도 $1,339kgcm^{-2}$로 가장 높았다. 액상 규산질 비료의 엽면시비시 절화장과 절화중은 1회 시비에서 가장 좋았고, 개화소요일수는 무처리에서 가장 짧았다. 규산질 비료의 엽면시비에 따른 줄기의 경도와 강도는 무처리에 비하여 시비구에서 높았으며, $60mg{\cdot}L^{-1}$, 1회 시비에서 경도와 강도가 가장 높았다. 줄기의 Si 함량은 무처리에 비하여 농도가 높아질수록 시비회수가 많을수록 Si의 함량이 높아지는 경향을 보였고, $30mg{\cdot}L^{-1}$의 농도로 2회 시비한 처리에서 무처리 대비 2배 이상 함량이 높았다.

• Journal of Ginseng Research
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• 제13권2호
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• pp.153-157
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• 1989

청경종 특성을 알기위하여 지상부 제형질, 광합성과 호흡 그리고 자식세대의 경색을 조사하였다. 청경종은 엽경종, 황열종의 경, 엽, 광합성과 호흡에 뚜렷한 차이가 나타나지 않았지만 5년근시 화경장 형질이 타 변종보다 길었다. 광합성에 있어서는 청경종이 뚜렷한 차이는 없는 경향이며 비교적 황열종이 높았으나 $20^{\circ}C$ 이상에서는 모든 변종에서 현저히 떨어지는 경향이었다. 청경종내 자식세대 일부는 경색이 분리되는 경향이나 자식사대가 거듭할수록 녹색경(청경종) 출현이 높았다.

• Journal of Ginseng Research
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• 제9권1호
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• pp.42-53
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• 1985

This study was carried out to obtain the basic information about the large scale propagation of ginseng (Panax ginseng C.A. Meyer). Therefore, the stem cuttings of 1-year old ginseng, treated with various concentrations of plant growth regulators for 5 seconds (quick dipping) and 24 hours (prolonged soaking), were cultured. The root formation of stem cuttings was varied with the concentrations, kinds, and treatment methods of plant growth regulators. Besides normal-looking roots various malformed roots were observed. In the prolonged soaking method, the culture of stem cuttings, treated with 10 ppm of IBA or NAA, resulted in profuse root regeneration. And stem cuttings, in quick dipping method, treated with 2000 ppm of IBA or NAA resulted in more excellent root regeneration. In general, IBA was more vigorous for the root formation than NAA, The treatment with 50 ppm kinetin or 100 ppm BA brought good result for the retardation of senescence of stem cuttings and BA treatment was more effective than kinetin. As for the saponin content of roots derived from stem cutting culture, the roots, formed by non-treatment of growth regulators, were higher in saponin content than those formed by treatment of growth regulators.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제27권1호
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• pp.111-127
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• 2024

There is an increasing concern in the United States regarding the workforce's ability to maintain a competitive position in the global economy. This has led to an increased interest in effective science, technology, engineering, and mathematics (STEM) education. The purpose of this study was to investigate the effect of STEM project-based learning (PBL) on students' self-regulation and motivation to learn. Secondary students (n = 60) participated in a STEM summer camp in which STEM PBL was utilized. Results showed that students increased their self-regulation skills (t = 2.83, df = 59, p = .004) and motivation (t = 2.25, df = 59, p =.004), with Cohen's d effect sizes of 0.395 and 0.404, respectively. Student-centered learning and peer collaboration while solving real-world problems were likely the greatest contributing factors to the outcomes. Educators should utilize the results to provide opportunities for students to experience STEM PBL.

• 한국산림과학회지
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• 제108권3호
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• pp.357-363
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• 2019

본 연구는 Kozak 수간곡선모델을 이용하여 우리나라 상수리나무의 입목수간재적표를 개발하고자 수행하였다. 전국의 분포하고 있는 상수리나무를 총 2,700본의 표준목을 벌채하여 수간고별 직경과 수간석해 자료를 수집하여 생장특성을 조사하였다. 수간곡선식의 적합도 검정을 위하여 적합도지수(Fitness index), 편차(Bias), 평균절대편차(Mean Absolute Deviation)를 이용하여 모델의 적합성을 판단하였다. 추정된 모델의 적합도지수는 97%로 나타났고 편차는 0.017, 평균절대편차는 1.118로 높은 적합도를 보였다. 또한 현행재적표와 신규재적표의 재적간의 차이를 분석한 결과, 통계적으로 유의적인 재적차이를 보였다(p = 0.0008, <0.005). 이는 현실림을 반영한 신규재적표를 이용하는 것이 목재자원량의 평가시 손실을 줄이고 국가 및 지자체의 산림통계의 정확도를 향상시킬 것으로 판단된다. 본 연구의 주요한 결과인 추정된 수간곡선식을 이용한 입목수간재적표는 우리나라의 주요 활엽수종인 참나무류 중 상수리나무의 생장 정보 및 합리적 경영을 위한 경영제표가 될 것으로 판단된다.

• Journal of Ginseng Research
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• 제8권2호
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• pp.172-177
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• 1984

Saponins in leaf and stem of Gynostemma pentaphyllum that was collected from Jeju Island were extracted by the method for ginseng saponin. Comparison by overlapping chromatogram(HPLC) of pentaphyllum on that of ginseng and cochromatogram and ginseng although ginsenoside Rg2, Rg1 and Rf might be in common with rare possibility. It seems to be little difference in the kind of saponin glycosides between leaf and stem of pentaphyllum. Saponin content in leaf of pentaphyllum was higher than in stem, and much higher than those in ginseng. The kind of saponin glycoside in pentaphyllum appeared to be less than 22 and greater than those in ginseng. There was almost no change in saponins of pentaphyllum in methanol for 3 years at room temperature.

• 한국발생생물학회지:발생과생식
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• 제21권4호
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• pp.449-456
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• 2017

The germline stem cells of the Drosophila ovary continuously produce eggs throughout the life-span. Intricate regulation of stemness and differentiation is critical to this continuous production. The translational regulator Nos is an intrinsic factor that is required for maintenance of stemness in germline stem cells. Nos expression is reduced in differentiating cells at the post-transcriptional level by diverse translational regulators. However, molecular mechanisms underlying Nos repression are not completely understood. Through three distinct protein-protein interaction experiments, we identified specific molecular interactions between translational regulators involved in Nos repression. Our findings suggest a model in which protein complexes assemble on the 3' untranslated region of Nos mRNA in order to regulate Nos expression at the post-transcriptional level.

• International Journal of Stem Cells
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• 제17권2호
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• pp.182-193
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• 2024

To address the limitations of animal testing, scientific research is increasingly focused on developing alternative testing methods. These alternative tests utilize cells or tissues derived from animals or humans for in vitro testing, as well as artificial tissues and organoids. In western countries, animal testing for cosmetics has been banned, leading to the adoption of artificial skin for toxicity evaluation, such as skin corrosion and irritation assessments. Standard guidelines for skin organoid technology becomes necessary to ensure consistent data and evaluation in replacing animal testing with in vitro methods. These guidelines encompass aspects such as cell sourcing, culture techniques, quality requirements and assessment, storage and preservation, and organoid-based assays.

• Archives of Plastic Surgery
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• 제40권6호
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• pp.666-675
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• 2013

Background Stem cells are a unique cell population characterized by self-renewal and cellular differentiation capabilities. These characteristics, among other traits, make them an attractive option for regenerative treatments of tissues defects and for aesthetic procedures in plastic surgery. As research regarding the isolation, culture and behavior of stem cells has progressed, stem cells, particularly adult stem cells, have shown promising results in both translational and clinical applications. Methods The purpose of this review is to evaluate the applications of stem cells in the plastic surgery literature, with particular focus on the advances and limitations of current stem cell therapies. Different key areas amenable to stem cell therapy are addressed in the literature review; these include regeneration of soft tissue, bone, cartilage, and peripheral nerves, as well as wound healing and skin aging. Results The reviewed studies demonstrate promising results, with favorable outcomes and minimal complications in the cited cases. In particular, adipose tissue derived stem cell (ADSC) transplants appear to provide effective treatment options for bony and soft tissue defects, and non-healing wounds. ADSCs have also been shown to be useful in aesthetic surgery. Conclusions Further studies involving both the basic and clinical science aspects of stem cell therapies are warranted. In particular, the mechanism of action of stem cells, their interactions with the surrounding microenvironment and their long-term fate require further elucidation. Larger randomized trials are also necessary to demonstrate the continued safety of transplanted stem cells as well as the efficacy of cellular therapies in comparison to the current standards of care.

• International Journal of Stem Cells
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• 제16권1호
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• pp.44-51
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• 2023

Background and Objectives: DNA methyltransferases (Dnmts) play an important role in regulating DNA methylation during early developmental processes and cellular differentiation. In this study, we aimed to investigate the role of Dnmts in neural differentiation of embryonic stem cells (ESCs) and in maintenance of the resulting neural stem cells (NSCs). Methods and Results: We used three types of Dnmt knockout (KO) ESCs, including Dnmt1 KO, Dnmt3a/3b double KO (Dnmt3 DKO), and Dnmt1/3a/3b triple KO (Dnmt TKO), to investigate the role of Dnmts in neural differentiation of ESCs. All three types of Dnmt KO ESCs could form neural rosette and differentiate into NSCs in vitro. Interestingly, however, after passage three, Dnmt KO ESC-derived NSCs could not maintain their self-renewal and differentiated into neurons and glial cells. Conclusions: Taken together, the data suggested that, although deficiency of Dnmts had no effect on the differentiation of ESCs into NSCs, the latter had defective maintenance, thereby indicating that Dnmts are crucial for self-renewal of NSCs.