• Advances in Computational Design
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• 제3권3호
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• pp.269-288
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• 2018

180 different 2D numerical analyses have been carried out to estimate the factor of safety (FOS) for rooted slopes. Four different types of vegetated coverage and a variety of slope geometry considering three types of soil have been evaluated in this study. The highly influenced parameters on the slope's FOS are determined. They have been chosen as the input parameters for developing a new practical relationship to estimate the FOS with an emphasis on the roots effects. The dependency of sliding mode and shape considering the soil and roots-type has been evaluated by using the numerical finite element model. It is observed that the inclination and height of the slope and the coverage type are the most important effective factors in FOS. While the soil strength parameters and its physical properties would be considered as the second major group that affects the FOS. Achieved results from the developed relationship have shown the acceptable estimation for the roots slope. The extracted R square from the proposed relationship considering nonlinear estimation has been achieved up to 0.85. As a further cross check, the achieved R square from a multi-layer neural network has also been observed to be around 0.92. The numerical verification considering different scenarios has been done in the current evaluation.

• 한국수학사학회지
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• 제22권4호
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• pp.29-40
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• 2009

중국 산학에서 방정식 풀이 방법은 고법(古法)과 구장산술(九章算術)의 개방술(開方術), 개입방술(開立方術)을 시작으로 가헌(賈憲)의 개방석쇄법(開方釋鎖法)을 걸쳐 증승개방법(增乘開方法)으로 완성된다. 본 논문에서는 이 방법들을 알아보고 조선의 산학자들이 그들의 산서에서 사용한 해법을 연구한다.

• 한국수학사학회지
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• 제27권6호
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• pp.387-394
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• 2014

Since ancient civilization, solving equations has become one of the most important subjects in mathematics and mathematics education. The extractions of square roots and cube roots were first dealt in Jiuzhang Suanshu in the setting of subdivisions. Extending these, Shisuo Kaifangfa and Zengcheng Kaifangfa were introduced in the 11th century and the subsequent development became one of the most important contributions to mathematics in the East Asian mathematics. The translation of coordinate axes plays an important role in school mathematics. Connecting the translation and Kaifangfa, we find strong didactical implications for improving students' understanding the history of Kaifangfa together with the translation itself although the latter is irrelevant to the former's historical development.

• 대한수학회보
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• 제50권4호
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• pp.1243-1259
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• 2013

In this paper, we study the root system of rank 2 hyperbolic Kac-Moody algebras. We give some sufficient conditions for the existence of imaginary roots of square length $-2k(k{\in}\mathbb{Z}_{>0}$. We also give several relations between the integral points on the hyperbola $\mathfrak{h}$ to show that the value of the symmetric bilinear form of any two integral points depends only on the number of integral points between them. We also give some generalizations of Binet formula and Catalan's identity.

• Restorative Dentistry and Endodontics
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• 제42권3호
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• pp.232-239
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• 2017

Objectives: The evaluation of iatrogenic dentinal defects in extracted teeth may be influenced by extraction forces and prolonged dry times. The purpose of this study was to compare the presence of dentinal defects in freshly extracted, periodontally compromised teeth with those in a group of teeth with uncontrolled extraction forces and storage time. Materials and Methods: The experimental group consisted of eighteen roots obtained from teeth extracted due to periodontal reasons with class II or III mobility. They were kept in saline and sectioned within 1 hour following extraction. The control group consisted of matched root types obtained from an anonymous tooth collection, consistent with previous dentinal defect studies. The slices were obtained at 3, 6, and 9 mm from the apex. The imaging process exposed all specimens to no more than 60 seconds of dry time. The ${\times}12.8$ magnification was used for the 9 mm slices and ${\times}19.2$ magnification for the 3 mm and 6 mm slices under light-emitting diode (LED) transillumination. The root canal spaces and periodontal tissues were masked to minimize extraneous factors that might influence the evaluators. Chi-square test was used for statistical analysis. Results: Dentinal defects were detected in 17% of the experimental group teeth, compared to 61% of control teeth (p = 0.015). Conclusions: LED transillumination assessment of freshly extracted roots with class II or III mobility showed smaller number of dentinal defects than roots with uncontrolled storage time and extraction forces. The use of freshly extracted roots with mobility should be considered for future dental defect assessment studies.

• Restorative Dentistry and Endodontics
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• 제40권1호
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• pp.58-67
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• 2015

Objectives: This study aimed to compare the accuracy of conventional intraoral (CI) radiography, photostimulable phosphor (PSP) radiography, cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) for detection of strip and root perforations in endodontically treated teeth. Materials and Methods: Mesial and distal roots of 72 recently extracted molar were endodontically prepared. Perforations were created in 0.2, 0.3, or 0.4 mm diameter around the furcation of 48 roots (strip perforation) and at the external surface of 48 roots (root perforation); 48 roots were not perforated (control group). After root obturation, intraoral radiography, CBCT and MDCT were taken. Discontinuity in the root structure was interpreted as perforation. Two observers examined the images. Data were analyzed using Stata software and Chi-square test. Results: The sensitivity and specificity of CI, PSP, CBCT and MDCT in detection of strip perforations were 81.25% and 93.75%, 85.42% and 91.67%, 97.92% and 85.42%, and 72.92% and 87.50%, respectively. For diagnosis of root perforation, the sensitivity and specificity were 87.50% and 93.75%, 89.58% and 91.67%, 97.92% and 85.42%, and 81.25% and 87.50%, respectively. For detection of strip perforation, the difference between CBCT and all other methods including CI, PSP and MDCT was significant (p < 0.05). For detection of root perforation, only the difference between CBCT and MDCT was significant, and for all the other methods no statistically significant difference was observed. Conclusions: If it is not possible to diagnose the root perforations by periapical radiographs, CBCT is the best radiographic technique while MDCT is not recommended.

• Journal of Plant Biotechnology
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• 제42권3호
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• pp.257-264
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• 2015

본 연구에서는 식물조직배양기법을 통해 생산된 부정근과 이들의 표준 한약자원 약용부위에서 추출된 전세포추출물의 FT-IR스펙트럼 분석을 통해 대사체 수준에서의 동등성을 비교 분석함으로써 보다 안전하고, 균일한 한약자원 약용부위의 대체 공급수단을 개발하고자 하였다. 이를 위해 대표적인 한약자원 품목인 백수오(Cynanchum wilfordii), 백출(Atractylodes japonica), 하수오(Polygonum multiflorum), 그리고 황기(Astragalus membranaceus) 등 4 종류 약용식물의 표준 한약자원 약용부위와 기내에서 생산된 이들의 부정근들을 FT-IR 분석에 사용하였다. FT-IR 스펙트럼 데이터의 PCA (principal component analysis)와 PLS-DA (partial least square discriminant analysis) 분석결과 백수오와 황기의 표준 약용부위 시료들 사이에서 전체 대사체 패턴이 매우 유사함을 알 수 있었다. 특히 이들 한약자원 품목들의 경우 기내생산 부정근 시료들과도 전체 대사체 패턴이 매우 유사함을 알 수 있었다. 본 결과로 미루어볼 때 백수와 황기의 경우 기내에서 대량생산된 부정근이 이들 한약자원 품목의 약용부위에 대한 새로운 공급수단으로 활용이 가능함을 보여주는 결과라 사료된다. 그러나 백출과 하수오의 부정근 시료들의 경우 전체 대사체 패턴이 이들의 표준 약용부위 시료들과 차이를 보였다. 또한 본 연구를 통하여 다양한 한약자원 품목들의 약용부위 시료들로부터 빠르고 간편하게 전체 대사체 수준에서 유사도 비교가 가능함을 알 수 있었다. 따라서 본 연구에서 확립된 FT-IR 스펙트럼기반 다변량통계분석 기술은 다양한 한약자원 약용부위 시료들의 대사체 수준 동등성을 식별하는 수단으로 활용이 가능할 것으로 기대된다. 더 나아가 본 기술이 한약자원품목들의 성분 표준화에 크게 기여할 수 있을 것으로 사료된다.

• 대한본초학회지
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• 제22권3호
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• pp.9-14
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• 2007

Objectives : This research was observed by examining the external and internal parts and the quantity of the surface components of the wild type and cultivar of Angelica dahurica in korea. Methods : The slice of the tested material mede by paraffin section technique was colored with Safranine Malachite Green contrast methods, and then observed and photographed by the microscope and examined the quantity of the surface components. Results : In the shape of the roots, the wild type had a very thin main root and 2 long roots, while the cultivar had a long root branched out from the short and thick main root making a square pyramid shape. Isoimperatorin was detected at Rt $17{\sim}18$ minutes. The wild type contained 0.56% while the cultivar contained it of 0.355%, thus the component of the wild type was about 1.5 times of that of the cultivar. Conclusions : It was thought that there might be also some differences in their genetic characteristics, etc.

• 한국수학사학회지
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• 제18권3호
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• pp.39-54
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• 2005

중국 산학에서는 구장산술의 제곱근과 세제곱근의 해법을 일반화하여 고헌이 도입한 증승개방법을 통하여 다항방정식의 해의 근사값을 구한다. 이 때 도구로 사용되는 조립제법에서 음수와 그 연산을 정확히 사용하지 않아서 번적, 익적이라는 개념이 나타나는데, 이는 조선 산학에도 그대로 사용되었다. 먼저 중국과 조선에서 번적, 익확에 대한 역사를 조사하고, 19세기 중엽에 조선 산학자 남병길과 이상혁이 번적과 익적에 대한 충분조건을 얻어내고 이를 증명한 사실을 밝혀낸다.

• Restorative Dentistry and Endodontics
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• 제40권4호
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• pp.286-289
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• 2015

Objectives: The aim was to evaluate dentinal crack formation after root canal preparation with ProTaper Next system (PTN) with and without a glide path. Materials and Methods: Forty-five mesial roots of mandibular first molars were selected. Fifteen teeth were left unprepared and served as controls. The experimental groups consist of mesiobuccal and mesiolingual root canals of remaining 30 teeth, which were divided into 2 groups (n = 15): Group PG/PTN, glide path was created with ProGlider (PG) and then canals were shaped with PTN system; Group PTN, glide path was not prepared and canals were shaped with PTN system only. All roots were sectioned perpendicular to the long axis at 1, 2, 3, 4, 6, and 8 mm from the apex, and the sections were observed under a stereomicroscope. The presence/absence of cracks was recorded. Data were analyzed with chi-square tests with Yates correction. Results: There were no significant differences in crack formation between the PTN with and without glide path preparation. The incidence of cracks observed in PG/PTN and PTN groups was 17.8% and 28.9%, respectively. Conclusions: The creation of a glide path with ProGlider before ProTaper Next rotary system did not influence dentinal crack formation in root canals.