• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.13-22
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• 2018

In this study, a governing differential equation for the bending problem of orthotropic rectangular plate is drived. It's exact solution for various boundary conditions is presented. This solution follows traditional method like Navier's solution or Levy's solution that transforms the governing differential equation into an algebraic equation by using trigonometric series. To obtain a solution by Levy's method, it is required that two opposite edges of the plate be simply supported. And the boundary conditions, for which the Navier's method is applicable, are simply supported edge at all edges. In this study, it overcomes the limitations of the previous Navier's and Levy's methods.This solution is applicable for any combination of boundary conditions with simply supported edge and clamped edge in x, y direction. The plate could be subjected to uniform, partially uniform, and line loads. The advantage of the solution is that it is the exact solution as well as it overcomes the limitations of the previous Navier's and Levy's methods. Calculations are presented for orthotropic plates with nonsymmetric boundary conditions. Comparisons between the result of this paper and the result of Navier, Levy and Szilard solutions are made for the isotropic plates. The deflections were in excellent agreement.

• The Mathematical Education
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• v.29 no.2
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• pp.117-139
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• 1990

본 연구는 국민 학교 산수 익힘책의 효율적인 활용 방안을 찾는 데 목적이 있으며, 이를 위하여 선행 및 문헌 연구와 "산수 익힘책"의 활용 실태를 조사하였다. 본 연구에서 수행한 연구 내용을 요약하면 다음과 같다. 가. 이론적 배경 연구 및 산수 익힘책의 개발 방향 문헌과 선행 연구를 통하여 보조 교과서의 특성에 따를 활용 방안 및 보조 교과서의 학습 내용에 따른 틀용 방안을 이론적으로 고찰하였고, "산수 익힘책"의 개발 방향 및 그 특색에 대하여 조사하였다. 나. 활용 실태 조사 사용하고 있는 "산수 익힘책"의 활용 실태를 파악하여, 활용 방안을 마련하는 기선 자료를 수집하기 위함이며, 조사 내용은 다음과 같다. 1) 조사 내용 (1) 교사의 측면에서 ㆍ "산수 익힘책"의 도움 정도 ㆍ "산수 익힘책"의 수업 시간에의 활응 목적, 방법 ㆍ "산수 익힘책"의 활용시 편리성 ㆍ 흥미성 ㆍ 활용 시기 ㆍ 가정 학습으로 부과시의 목적 ㆍ 문제 풀이 결과 확인자 ㆍ 교육 과정 반영 정도 ㆍ 개선점 (2) 학부모의 측면에서 ㆍ"산수 익힘책"의 활용 목적 ㆍ "산수 익힘책"의 활용 정도 ㆍ "산수 익힘책"의 도움 정도 ㆍ 학부모의 역할 정도 ㆍ "산수 익힘책"에 대한 학생의 흥미도 ㆍ "산수 익힘책"의 개선점 2) 조사 도구 조사 내용에 대하여 국민 학교 1, 2, 3학년 담임 교사용과 학부모용의 질문지를 각각 작성하여 전문가의 검토를 거쳐 "산수 익힘책"의 활용에 관한 실태 조사지를 개발하였다. 이 때, 각 학년별 교사용끼리, 학부모용끼리의 질문지의 문항은 서로 같게 하였으며 교사용은 25문항, 학부모용은 16문항으로 구성하였다. 다. 활용 방안 구안 "산수 익힘책"의 개발 방향과 "산수 익힘책"의 활용 실태 조사에 기초하여 산수 익힘책의 효율적인 활용 방법을 수업 절차에 따라 구분하였다. 수업 절차는 여러 가지 형태가 있지만 본 연구에서는 KEDI의 수업 과정 일반 모형에 준하여 산수 익힘책의 활용 방법을 구안하였다. 라. 활용 방안을 구안하였다. 1) 적용 목적 구안된 "산수 익힘책"의 활용 방안의 현장 적용은 활용 방안의 질을 높이려는 대에 중요한 목적이 있다. 적용 결과는 현장 적용 가능성을 판단할 수 있는 입증 자료가 될 수 있을 뿐만 아니라, "산수 익힘책" 관심을 가지고 있는 교사나 연구자에게 학력 향상 가능성에 대한 경험적 근거를 제시함으로써 중요한 시사를 줄 수 있을 것이다. 2) 적용 결과 전체적으로 적응 수업이 실시된 지 3주후 부터는 활용 방안에 익숙해져 "산수 익힘책"을 효과적으로 활용할 수 있었다. 그 뿐만 아니라 자율학습시 학생들 스스로가 상호 확인을 하고, 서로 결손이 있는 부분을 가르쳐 주는 협동 학습이 이루어졌다.

• Industry Promotion Research
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• v.6 no.3
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• pp.37-47
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• 2021

This study is based on 'Sangkwan' in 'Jeokcheonsucheonmi' among Myeongri classical theory as a guideline, and is a consideration research on past 'Sangkwan' in the rest of Myeongri classical theory. The first words about 'Sangkwan' in the original text is that the interpretation is very difficult when Sangkwan looks at 'Jeongkwan'. When we say 'Jeongkwan', it contains the interpretation on the person who should take on the heavy responsibility of the state in the monarchy, and there is a concern about how it can be easily interpreted by neglecting it because 'Sangkwan' have a bad effect on 'Jeongkwan'. Unlike modern times, in the past, there was no other way but to become government officials to be successful socially and accumulate wealth. There should be big difference in standard of fortune and success in an era where success conditions and opportunities were difficult to be given. That is, it was though in the past that 'Sangkwan' which has a bad influence on 'Jeongkwan' have a detrimental effect awfully. However, in today's scientific society, the use of 'Sangkwan' which has a bad influence on 'Jeongkwan' has come to light in a wide variety of places. Therefore, this study is to lay a foundation for the expansion of reinterpretation and utilization methods suitable for the times through the consideration of classical 'Sangkwan'.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.1
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• pp.28-37
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• 2002

In this study nonlinear dynamic behaviors of towed tow-tension cables are numerically analysed. In the case of a taut cable analysis, a bending stiffness term is usually neglected due to its minor effect but it plays an important role in a low-tension cable analysis. A low-tension cable may experience large displacements due to relatively small restoring forces and thus the effects of fluid and geometric non-linearities become predominant. The bending stiffness and non-linearity effects are considered in this work. In order to obtain dynamic behaviors of a towed low-tension cable, three-dimensional nonlinear dynamic equation is described and discretized by employing a finite difference method. An implicit method and Newton-Raphson iteration are adopted for the time integration and nonlinear solutions. For the calculation of huge size of matrices. block tri-diagonal matrix method is applied, which is much faster than the well-known Gauss-Jordan method in two point boundary value problems. Some case studies are carried out and the results of numerical simulations are compared with those of a in-house program of WHOI Cable with good agreements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7061-7070
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• 2015

Multi-Response Surface Optimization aims at finding the optimal setting of input variables considering multiple responses simultaneously. The Weighted Mean Squared Error (WMSE) minimization approach, which imposes a different weight on the two components of mean squared error, squared bias and variance, first obtains WMSE for each response and then minimizes all the WMSEs at once. Most of the methods proposed for the WMSE minimization approach to date are classified into the prior preference articulation approach, which requires that a decision maker (DM) provides his/her preference information a priori. However, it is quite difficult for the DM to provide such information in advance, because he/she cannot experience the relationships or conflicts among the responses. To overcome this limitation, this paper proposes a posterior preference articulation method to the WMSE minimization approach. The proposed method first generates all (or most) of the nondominated solutions without the DM's preference information. Then, the DM selects the best one from the set of nondominated solutions a posteriori. Its advantage is that it provides an opportunity for the DM to understand the tradeoffs in the entire set of nondominated solutions and effectively obtains the most preferred solution suitable for his/her preference structure.

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.262-267
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• 1998

We evaluated Ambrosia artemisiifolia var. elatior, Ambrosia trifida, Rumex crispus which were reported to have good phytoremediatibility in different concentrations of Cu and Cd. Different growth responses were found in different heavy metal concentrations. Good growth rate for A. trifida and A. artemisiifolia var. elatior in Cu and Cd treatments and poor growth for R. crispus in Cd treatment were found. Although growth was retared in all tested weeds up to 200ppm for Cu and 50ppm for Cd, the high amount of heavy metal uptake indicated that these weeds could be used as phytoremediation. The choice of proper plant for bioremediation in different sources of heavy metal pollution seems important. In this regard, A. trifida which showed little variation in Cu accumulation in shoot under different Cu concentrations could be used for phytoremediation and phytostabilization.

• Journal of The Korean Association For Science Education
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• v.33 no.7
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• pp.1385-1402
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• 2013

This study analyzes pre-service teachers' PCK dealing with visualization of the contents related to boiling point elevation and teaching methods in mock-lessons. As a result of analyzing pre-service teachers' knowledge based on PCK factors, most of the pre-service teachers accentuated on understanding boiling point elevation conceptually, whereas some of the others inclined to make students understand boiling point elevation in a scientific way, let the kids use numerical formulas to describe the concept, and motivate them to learn through the examples in real life. The pre-service teachers represented majority of the important facts of boiling point elevation as the knowledge required to understand things conceptually. However, they did not focus on improving the scientific thinking and inquiring levels of the students. Also, the pre-service teachers tended to teach at the level and order of the textbook. In some other cases, they considered the vocabularies and materials in the textbook (which could have been highlighted in the editing sequence) as the main topic to learn, or regarded the goal as giving students the ability to solve exercises in the textbook. It turned out that the pre-service teachers had a low level of knowledge of their students. It is recommended that they should make use of the materials given (such as data related to the misconception of students) during the training session. The knowledge of teaching and evaluating students was described superficially by the pre-service teachers; they merely mentioned the applications of models, such as the cyclic model and discovery learning, rather than thinking of a method related to the goals, or listed general assessment methods.

• Journal of Digital Convergence
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• v.8 no.1
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• pp.41-53
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• 2010

In this paper, we discuss patent pool and a patent valuation scheme for fair royalty distribution among the patents in a pool. In the knowledge-based economy, intellectual capital-the accumulation of technology and know-how-is recognized as the most important source of company's competitive advantage and economic growth. By providing exclusive rights to patent holders, the patent system aims to encourage innovation-invention & commercialization of new technologies-in order to raise the standard of living. However, drawbacks of patent system, which occur as the number of patents issued increases rapidly and patent ownership is fragmented, may slow down the innovation efforts seriously. A promising solution is the patent pool approach, which was for instance employed by the U.S. congress during World War I to free the airplane manufacturers from the patent tangle by letting them license all the patents for a fee. It is necessary to figure out relative technological contribution of patent for fair distribution of royalty revenues among patent holders. The Rating/Ranking Method seems to fit to that valuation purpose. We examined technology valuation models from various organizations and selected a set of more influential valuation factors which can be incorporated as scoring criteria in the Rating/Ranking Method.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.35.5-36
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• 2021

'역상고성'은 '신법산서'에 수록되어 있는 티코브라헤의 역법체계와 그 밖의 천문 내용들을 중국인 천문학자들에 의하여 확실하게 정리를 하였지만 '역상고성'에 따른 추보는 천상과 불일치를 보게 되었다. 藪內淸(야부우치 키요시) 저(1969), 유경로 역(1985)에 의하면 이러한 불일치는 옹정 8년 6월 초 1일의 일식이었는데 예보의 오류를 정정한다는 것을 중국 천문학자들이 감당하기 어려웠다. 퀘글러(Ignatius Kögler, 戴進賢, 1680~1746)와 페레이라(Andreas Pereira, 서무덕(徐懋德), 1690-1743) 등의 선교사 천문학자들이 칙명을 받아 종사하게 되고, 이들이 중심이 되어 '역상고성'보다 더 진보된 서양천문 역법에 기초를 둔 역서가 편찬되게 되었다. '신법산서'와 '역상고성'은 모델에서는 평원(平圓)을 사용하지만 '역상고성후편'에서는 타원(楕圓) 모델을 사용하게 된다. 건륭 7년(1742년)에 10권이 완성되어 '역상고성후편'이라 명하였다. 타원모델을 채택하였지만 지동설에 대한 내용은 전혀 기술되어 있지 않다. 아마도 태양이나 달의 운동을 추보하는데 지구를 중심으로 해야 하기에 이에 대한 언급을 필요치 않았을 수도 있다. '역상고성후편' 은 태양과 달의 운행, 일식과 월식에 대해서만 다루고 있다.그러나 '역상고성'에서는 청몽기차나 지반경차를 티코브라헤의 표 값을 그대로 사용하였고, 이 값들이 관측과 관련이 되어 있음을 설명하려는 무리를 두고 있다. 너무 정확하게 값들이 관측 값들로부터 유도되어 의심이 갈 정도이다. 카시니(Giovanni Domenico Cassini, 喝西尼, 1625~1712)는 자신의 동료 리셰와 함께 파리와 프랑스령 기아나 카이엔에서 충의 위치에 있는 화성과 부근 별의 고도를 관측하여 충의 위치에 있는 화성의 시차를 측정하여 최초로 태양과 지구 사이의 거리를 어림하고, 태양의 지반 경차를 현재와 값과 거의 비슷하게 얻었다. '역상고성후편'에서는 이 내용을 상세하게 다루고 있다. 또한 대기에서 입사각과 굴절각 사이에 Snell의 법칙이 성립하는데 이를 이용하여 모호하게 알았던 청몽기차를 대기의 굴절을 이용하여 현재의 값과 비슷한 값을 얻어 사용할 수 있게 되었다. 이는 모든 천체의 위치를 관측하는데 있어서 매우 정확한 값들을 얻을 수 있게 되고 이에 따라 황도-적도 경사각도 정확하게 얻어진다. '역상고성후편'은 옹정원년을 역원으로 하고 있다. 태양의 운행에 있어서 케플러의 타원 궤도를 이용하게 된다. '신법산서'와 '역상고성'에서는 평균근점이각 M을 모델에서 보여 줄 수 있지만 타원 궤도에서는 이 각이 면적각으로 주어지고, 원 대신 타원을 다루기에 쉽지 않다. 현재는 케플러 방정식을 풀어 가감차를 구하게 되는데 이를 기하학적으로 풀이하는 차적구적법을 소개하고 있다. 이와 함께 면적을 이용하여 타원계각과 타원차각을 구하는 차각구각법도 소개한다. 타원계각과 타원차각을 모두 고려하였기에 현재의 태양의 운동을 기술하는 타원모델과 완벽하게 같다. 다만 사용하는 상수가 아주 조금 다를 분이다. 태양의 경도를 추보하는 방법도 동지점을 기준으로 하고 현재의 방법과 동일하다. 달의 운행도 타원 궤도를 사용한다. '역상고성후편'의 내용은 우리나라의 전해져서 1860년 남병길이 쓴 '시헌기요(時憲紀要)'에는 태양, 달, 일·월식, 오행성의 운동, 항성의 위치, 시간 등을 추보하는데 필요한 내용들이 매뉴얼화 되어 기록되어 있고, 1862년 남병철이 쓴 '추보속해(推步續解)'에도 같은 내용을 담고 있다.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.783-790
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• 2023

The term edutech has recently been attracting attention as the convergence of education and technology is emphasized. Schools are also exploring teaching methods using edutech. The purpose of this study is to analyze the satisfaction of 210 radiology students after using Quizn Platform and the difference in satisfaction with Quizn Platform according to general characteristics. The research results are as follows. First, as a result of the satisfaction analysis according to class type, the following order was practical class, theory + practice class, and theory class. Second, the desired teaching methods among theory classes according to general characteristics were core classes (quiz solving), lecture-style classes, discussions, and discussion classes. Third, 'Quizn was used appropriately in class.' had the highest score at 4.27±0.60, and 'I am very interested in this subject.' had the lowest score at 3.98±0.74. Additionally, there was no significant difference in response to the teaching method (p>0.05). Fourth, 'Applying Quizn to class was interesting and fun' showed the highest score at 4.24±0.94, and 'Institutional support must be provided to continue using Quizn at 3.49±0.96. Additionally, there was no significant difference in satisfaction with classes according to gender and age (p>0.05). As a limitation of this study, although we investigated the satisfaction of students using Quizn, we were unable to investigate the satisfaction of instructors who interact with students. In the future, research that considers instructor satisfaction in classes using edutech should be conducted. Universities must provide institutional support and continuous interest until edutech is selected and utilized.