• School Mathematics
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• v.9 no.4
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• pp.523-533
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• 2007

This article focused the meaning of Pythagoras' and Euclid's proof about the Pythagorean theorem in a historical and mathematical perspective. Pythagoras' proof using similarity is based on the arithmetic assumption about commensurability. However, Euclid proved the Pythagorean theorem again only using the concept of dissection-rearrangement that is purely geometric so that it does not need commensurability. Pythagoras' and Euclid's different approaches to geometry have to do with Birkhoff's axiom system and Hilbert's axiom system in the school geometry Birkhoff proposed the new axioms for plane geometry accepting real number that is strictly defined. Thus Birkhoff's metrical approach can be defined as a Pythagorean approach that developed geometry based on number. On the other hand, Hilbert succeeded Euclid who had pursued pure geometry that did not depend on number. The difference between the proof using similarity and dissection-rearrangement is related to the unsolved problem in the geometry curriculum that is conflict of Euclid's conventional synthetical approach and modern mathematical approach to geometry.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.2
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• pp.29-33
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• 2011

Research about the geometry design of lead pin was carried based on the normal or shear stress of the interface between a lead pin and a PCB in terms of delamination failure. The taguchi method with four design factors of three levels and FEA(Finite element Analysis) are carried under $20^{\circ}$ bending and 50 ${\mu}m$ tension of lead pin. The contact width, d2, between head round and copper pad in PCB is the highest affection factor among design factors by analysis of contribution analysis. Equivalent von Mises stress of 18.7% reduction design is obtained by the parameter design of the taguchi method. Maximum normal stress occurred at contact position between solder outer surface and a Cu pad in PCB. Also, maximum shear stress happened at contact position between solder outer surface and SR layer of PCB. From these calculated results, delamination of the PGA package may be occurred from outer interface of solder to inner interface of solder.

• Korean Journal of Clinical Pharmacy
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• v.19 no.2
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• pp.96-104
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• 2009

배경: 당뇨병 환자에게 관상동맥심질환은 생존률, 건강 상태 유지 및 삶의 질에 주요한 영향을 미치는 합병증이며 적극적인 당뇨병 치료는 이러한 심혈관 합병증을 예방할 수 있으나 당뇨병의 적극적 치료와 관리에는 많은 비용이 소요된다. 목적: 제2형 당뇨병 환자를 대상으로 메트포르민과 글리메피리드 병합요법과 메트포르민과 피오글리타존 병합요법의 비용-효과성을 비교하고자 하였다. 연구방법: 마르코프 코호트 프로세스(Markov Cohort Process Model) 모형을 이용하여 비용-효과분석을 실시하였다. 연장된 수명 (life years gained, LYG)과 삶의 질(quality)을 보정하여 증가된 QALYs를 주요 효과 지표로 측정하였고, 총비용으로는 직접의료비용과, 환자와 가족의 교통비를 직접비의료비용으로 고려하였고 환자와 가족의 시간비용을 간접비용으로 포함하였다. 연구결과: 비용-효과분석 결과, 메트포르민과 글리메피리드 병합요법의 경우 총 비용은 5,962,288원, 효과는 7.94LYG, 6.43QALY이었다. 반면 메트포르민과 피오글리타존 병합요법은 총 비용 10,982,243원, 효과 8.62LYG, 6.99QALY으로, 점증적 비용-효과비(ICER)는 7,402,663원/LYG과 8,934,546원/QALY 이었다. 결론: 우리 사회의 연장된 수명(LYG)에 따른 지불의사가 700만원 이하인 경우는 메트포르민과 글리메피리드 병합요법이 비용-효과적인 대안이며 700만원 이상인 경우에는 메트포르민과 피오글리타존 병합요법이 비용-효과적인 대안이 될 수 있다.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.35-40
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• 2007

The pull strength and fracture mechanism were investigated to evaluate the reliability and compatibility of Sn-8Zn-3Bi joints, the solder paste on lead and lead-free plating under thermal shock conditions. At the Sn-8Zn-3Bi solder joint, no crack initiation was observed during thermal shock test. After 1000 cycles, the strength of the solder joint decreased not sharply but reduced gradually compared with initial conditions. The decrement of strength was affected by ${\gamma}-Cu_5Zn_8$ IMC growth which caused the IMC fracture on the fracture surface and a change in fracture mode and initial crack point. Clearly, the Sn-8Zn-3Bi solder shows good reliability properties and compatibility with lead-free plated Cu LF under thermal shock temperatures between 248K and 423K.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.7
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• pp.701-707
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• 2011

The aim of this paper is to develop a collaborative design system that can facilitate remote modification and control of a 3D solid model through the Internet. It enables the users to resolve conflicting viewpoints about an issue and collaborate to design a tangible object within a given set of constraints. In order to optimize the collaborative design system, we focus on the results obtained by using the collaborative design method for the real-time modification of a 3D solid model in a distributed environment. It also provides the method of managing the consistency between design entities. The efficiency of the system is verified by implementing it in a distributed environment.

• Composites Research
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• v.30 no.6
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• pp.338-342
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• 2017

In this paper, evaluation method of structural integrity of cylindrical composite lattice structures was conducted. A finite element analysis was used to evaluate the structural integrity of composite lattice structures. In order to verify the optimal finite element in the evaluation of the structural integrity, finite element models for cylindrical composite lattice structure were generated using beam, shell and solid elements. The results of the finite element analyses with the shell and solid element models showed a good agreement. However, considerable differences were found between the beam element model and the shell and solid models. This occurred because the beam element does not take into account the degradation of the mechanical properties of the non-intersection parts of cylindrical composite lattice structures. It was found that the finite element analysis of evaluation of structural integrity for cylindrical composite lattice structures have to use solid element.

• Korean Journal of Materials Research
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• v.10 no.8
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• pp.551-557
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• 2000

Cu-based leadframe sheets were oxidized ic a hot alkaline solution to black-oxide layer on the surface and molded with epoxy molding compound(EMC), and finally machined to form sandwiched double-cantilever beam(SDCB) and sandwiched Brazil-nut(SBN)specimers to measure the adhesion strength of leadframe-EMC interface. The SDCB and the SBN specimens were designed to measure the adhesion strength in terms fracture toughness under puasi-mode I and mixed mode loadinf, respectively. After the tests, fracture surfaces were analyzed paths were observed in the SDCB-tested speciments, failure paths varied with crack speed and loading conditions.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.1-8
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• 1989

Ten cultivars of malting barley grown at four locations were malted and assayed for six enzymes involved in the degradation of nucleic acids. Among these enzymes were deoxyrinonuclease, ribonuclease, phosphodiesterase, 3'- and 5'- nucleotidases and phosphomonesterase. Activities of all enzymes in five-day malts were significantly affected by variety and location of growth. The average levels of ribonuclease, deoxyribonuclease, 3'-nucleotidase and 5'-nucleotidase of 80 five-day malts were 11.2, 5.7, 5.6 and 1.2 units per gram of malt, respectively. Six-rowed barley malts contained higher levels of deoxyribonuclease, phosphodiesterase and 3'-nucleotidase than those of two-rowed barley malts, while two-rowed barley malts contained significantly higher ribonuclease levels than those of six-rowed barley malts.

• Journal of the Korean Chemical Society
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• v.25 no.6
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• pp.383-389
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• 1981

Thianthrene cation radical perchlorate reacts with N-arylsulfonamides such as p-toluenesulfonanilide, benzenesulfonanilide, N-(2-methylphenyl)benzenesulfonamide, and N-phenyl-p-toluenesulfonanilide to give 5-(p-N-p-toluenesulfonamidophenyl)-(1a), 5-(p-N-benzenesulfonamidophenyl)-(1b), 5-(4-N-benzenesulfonamido-3-methylphenyl)-(1c), and 5-(p-N-phenyl-N-p-toluenesulfonamidophenyl thianthrenium perchlorate (1d), respectively. In the meantime, 1d reacts further with thiathrene cation ratical to form diperchlorate(1e). The structure of 1a~1e is very similar to 5-(p-acetamidophenyl) thianthrenium perchlorate which has been obtained from the reaction with acetanilide. However, the discrepancy in the stoichiometry between two reactions indicates that the reaction with sulfonamide appears not to proceed with a single mechanism.

• Journal for History of Mathematics
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• v.21 no.2
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• pp.55-70
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• 2008

This study is about the Data which is one of Euclid's writing. It dealt with the organization of contents, formal system and mathematical meaning. First, we investigated the organization of contents of the Data. Second, on the basis of this investigation, we analyzed the formal system of the Data. It contains the analysis of described method of definition, proposition, proof and the meaning of 'given'. Third, we explored the mathematical meaning of the Data which can be classified as algebraic point of view, geometric point of view and the opposite point of view to 'The Elements'.