• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.420-425
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• 2010

In the process of warm forging, billet is heated up to $800^{\circ}C$ and located in the upper part of die block impression. The scattered oxidized scale may cause workers burn and shortening of die life sticking to the die block impression. The separating materials sprayed in die block cause harmful dust, harmful mist, fume, and bad odor which contaminate workshop environment. The process is classified as one of the avoided jobs and make the planned output achievement difficult. Development of an elimination device to clear out the contaminating materials in the workshop and improvement of the unsatisfactory maintenance method to fix the abrasion of die block impression which delays the dead line, cost increases needs to be developed. In this research, I tried to solve the problems caused in warm forging of bronze pipe joint such as the billet heating process, die maintenance, and manufacturing cost through improvement of warming forging manufacturing method and die maintenance method and eliminating harmful gas which will make the workshop more environment friendly.

• Journal of Conservation Science
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• v.31 no.3
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• pp.309-318
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• 2015

The staff given with chair to Yi Gyeong-seok, senior official over 70 years old by King Hyeonjong of Joseon Dynasty is representative handcraft of Joseon Dynasty. Results of analysis on the metallic decoration show that the metallic ornament of the end part which is connected to the spade was made by rolling of iron plate and brass plating. The plated part is limited to the ornament of the end part connected to the spade and the plating was not applied to the spade. Brass including 20% zinc was used for the connecting part of guard while brass gilded iron was used for the spade. This suggests that the tone of the connecting part of the guard and the spade was not different for reason of visual harmonization. Potential applied plating method can be amalgam, dippping in molten brass, and brushing but the analysis result suggests that dipping in molten brass method is the most likely accepted method. The brass guard of knife was joined by tin-lead solder. Rivet used to fix the blade was made by pure iron as an optimum material which satisfies flexibility and strength.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.5 no.2
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• pp.24-30
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• 1999

The migration mechanism of trace elements, Pb, Cd, Cu, Zn and Sn from brass food-contact utensiles was investigated. The migration of metals from brass was affected by the migration temperature (30, 60, 80 and $95^{\circ}C$), the simulant pH (2.5, 4.3, 6.0 and 7.0) and the migration time (30, 90, 180 and 360 min.). The amount of Pb migration was maximum at $95^{\circ}C$ with pH 2.5. This study indicated that the equilibrium of Pb migration was reached at 180 minutes. The mechanism of Pb migration was investigated with Scanning Electron Microscope (SEM) and Electron Probe Micro Analyzer (EPMA). To correlate the relations between the migration and the content of Pb in brass samples, ten brass samples having known content of Pb (the quantities of Pb in brass ; 0, 0.02, 0.09, 0.1, 0.2, 0.5, 0.9, 1.4, 5.4 and 9.2% (w/w)) were tested in the following conditions, 4% acetic acid, $95^{\circ}C$ and 30 minutes. The result represented that content of Pb in brass samples must be below 0.2% (w/w) to satisfy the 1.0 ppm (as Pb) of Korea Food Code.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2002.05a
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• pp.54-54
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• 2002

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.45 no.10
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• pp.26-36
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• 2016

• Journal for History of Mathematics
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• v.9 no.2
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• pp.30-42
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• 1996

최근 <수학기초론>이란 용어는 Burali-Forti paradox 이후 족(class)과 집합(set) 개념을 이해하려는 시도에서 출발한 20세기적 문제에 적용되고 있다. 이 글에서는 그 해결책으로 제시된 주의ㆍ주장 중 논리적인 모순을 해결하기 위한 Russel의 논리주의적 공리론에 바탕을 두고 살펴보려고 한다. 제 2장에서는 무한의 심연 속에 웅크리고 있는 집합론에서의 역설과 발생 원인에 대하여 살펴보았다. 제 3장에서는 공리론적 집합론 중에서 러셀의 유형론과 그것을 단순화시킨 현대의 유형론을 살펴보고, ZF 집합론과 ZF 집합론의 연장인 처치 집합론의 기본 공리를 살펴보았다.

• Communications of Mathematical Education
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• v.11
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• pp.201-233
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• 2001

보통 문장제(일량, 거리, 속도 문제, 시계 문제, 농도 문제, 개수 세기, 측도 영역)는 초등학교부터 반복하며 나오며 대학 수학 능력 시험에서는 외적 문제 해결능력으로 측정되기도 한다. 문장제를 해결하는데는 사고가 여러 단계로 이루어져야 한다. 따라서 일반적으로 문장제는 난해하므로, 조직적이고 전문적인 학습지도가 이루어져야 한다. 하지만 입시위주의 교육 등 여러 여건상 잘 이루어지지 않고 있는 것이 현실이다. 본 연구에서는 문장제의 문제 해결에 필요한 해결요소를 발견하고 저해 요인을 없앨 수 있는 지도 방안으로서 소집단 토의학습에 문제해결 전략을 이용하여, 효율적인 문장제 지도 방안을 연구하고 상이한 문제에 접근하는 방법, 문제를 이용하는 방법 등을 토의학습을 통하여 다양한 풀이방법을 해결하면서 이를 통하여 사고력을 신장할 수 있도록 연구한다.

• Journal of Adhesion and Interface
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• v.4 no.1
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• pp.28-34
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• 2003

Steel tire cords were subjected to plasma polymerization coating of acetylene in order to enhance the adhesion to rubber compounds. Plasma polymerization coating was varied to plasma polymerization coating of acetylene, argon plasma etching+plasma polymerization, or argon plasma. etching+plasma polymerization with Ar carrier gas. Adhesion was evaluated via TCAT samples and compared to those with brass coated tire cord. For durability study, plasma polymer cooled tire cords were aged in lab atmosphere for 1, 3, 5, 10 or 15 days, while TCAT specimens prepared with plasma polymer coated tire cords were aged in distilled water, 10% NaCl solution or $100^{\circ}C$ oven for 1, 2, 3 or 4 weeks. After testing, failure surfaces were analyzed with SEM/EDX. Among the treatments, the highest adhesion was obtained by Ar etching+acetylene plasma. polymerization coating with Ar carrier gas, providing almost same pull-out force as the brass coated tire cords. Upon the aging of the tire cords in the lab atmosphere, brass coated tire cords provided better adhesion than plasma polymer coated tire cords, while the TCAT samples with plasma polymer coated tire cords exhibited similar or slightly superior durability to those with brass coated tire cords.

• Resources Recycling
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• v.16 no.6
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• pp.39-45
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• 2007

Optimum condition for neutralization has been studied to remove the copper and zinc ions from spent sulfate solutions which resulted from the acid washing of the base of brass bulb. Chemical distribution of copper and zinc species and the variation of solubility of the two ions with solution pH were obtained by considering the complex formation reaction and mass balance. Removal percentage of zinc was more sensitive to solution pH than that of copper. This results from the fact that the solubility of zinc is higher than that of copper. The form of coagulant affected little the removal percentage of zinc, while addition of coagulant as the phase of solution resulted in higher removal percentage of copper than as the phase of solid.

• Communications of Mathematical Education
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• v.14
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• pp.1-25
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• 2001

초${\cdot}$중등학교 수학교육에 있어서 문제해결에 대한 관심은 전세계적으로 점점 높아지고 있다. 우리 나라 에서는 문제해결 교육을 제 4차 교육과정 개정부터 시작하여 제 7차 교육과정에서도 아주 중요시 하고있다. 이렇게 교육과정의 변화에도 불구하고 수학 교육헌장에서 교사들의 문제해결에 대하여 갖는 인식도나 실천적 의지는 매우 부족하다. 이런 관점에서 첫째는 문제해결력에 관한 제 7차교육과정의 교과서를 분석함으로써 문제해결 지도에 사용되고 있는 문제의 유형을 분석하였다. 둘째는 교사들의 설문지를 통하여 수학 교육에서 문제해결을 위한 교사의 신념을 조사하여 교육 현장에서 문제해결력의 문제점을 분석하여 앞으로의 개선책을 알아본다.