• 한국주조공학회지
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• 제36권3호
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• pp.81-87
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• 2016

In this study, the effect of scrap ratio on the mechanical properties of Zr alloys was studied. Oxygen content in the ingot cake increased rapidly with increasing fraction of scrap, which can be attributed to the surface oxide of scrap including small pieces of turning, chips, etc. Iron content did not increase much with the increasing addition of scrap, suggesting scrap materials was well reserved in the iron-free container. As-cast structure of Zr alloy with the scrap:sponge ratio displayed plate/or needle ${\alpha}$ phase and no appreciable change of the cast structure was observed with change of scrap fraction. The strength increases with increasing fraction of scrap, which can be attributed to the increase of oxygen content. The ductility decreased slightly with increase of scrap fraction. Dislocation-oxygen interaction is known to increase the strength at the expense of ductility. Ingot cake with intentionally added $Fe_2O_3$ exhibited the drastic decrease of the formability, even exhibited the brittle fracture behavior during rolling. The oxidation resistance, however, increased with the increase of scrap fraction because of high oxygen content, which may prevent more penetration and diffusion of oxygen into matrix.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.94-94
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• 2013

The Cr-Zr-N films have much improved mechanical properties and very smooth surface roughness. However, in spite of their outstanding properties, the Cr-Zr-N coatings revealed their mechanical properties deteriorated severely with increasing Zr content at $500^{\circ}C$ ecause of very rapid oxidation. Recently oxynitride films have been widely studied due to their excellent unique mechanical properties and oxidation resistance. In this work, CrZr-O-N films with various O contents were synthesized by unbalanced magnetron sputtering with Cr-Zr segment targets (Cr:Zr volume ratios is 1：1) and all films were prepared in a nitrogen rich mixture of N2 and O2. Characteristics such as crystalline structure, hardness and chemical composition as a function of the O content were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), microhardness testing system and energy dispersive spectroscopy (EDS). Results showed that the thin films had dense and compact microstructure as O content in the films increases. The microstructure of the thin films consisted of mainly crystalline Cr (Zr)N phase and Cr2O3 phase. The maximum hardness and elastic modulus of the films was measured to be approximately 33.2 GPa and 280.6 GPa from the films with low content of O elements. Detailed experimental results will be presented.

• 대한수학교육학회지:학교수학
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• 제17권4호
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• pp.555-570
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• 2015

2015년 9월 새로운 교육과정에 대한 총론 및 각론이 확정 고시될 계획이며 이에 따른 교과용도서 개발이 이루어지게 된다. 교과서는 교수 학습 내용의 방향과 범위를 결정하고 통제하는 역할과 기능을 지니고 있기 때문에 학생과 교사가 만나는 수업의 장에서 교과서는 매우 중요한 역할을 한다. 따라서 교과서의 내용 구성에 따라 수업에 많은 영향을 미치게 된다. 본 연구는 교과서 내용 영역별 세부 학습내용 구성의 차이점을 정적분의 활용을 중심으로 분석하고 이를 토대로 설문을 구성하여 14개 시 도교육청 고등학교 수학교사 369명을 임의표집하여 설문조사를 실시하였다. 설문 조사 결과를 분석하여 교과서 내용 영역별 세부 학습내용 구성의 차이에 따라 발생되어질 수 있는 교사의 교수 내용 및 방법과 학생들의 수학 학습에 미치는 영향을 탐색하였다. 이를 통하여 교과서 세부 학습내용의 구성에 대한 시사점을 제공하고 교과서 편찬 체제에 대한 개선점 도출을 그 목적으로 하고 있다.

• 유기물자원화
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• 제8권2호
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• pp.85-92
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• 2000

자연간석지 토양을 인공간석지에 인공간석지 토양을 자연간석지에 이식하고, 이식토양의 물리화학적 및 생물학적 특성의 변화를 추적하였다. 또한 실트함량과 유기물함량이 미생물현존량에 미치는 영향에 관해서 실내실험을 통하여 검토하였다. 자연간석지 토양을 인공간석지에 인공간석지 토양을 자연간석지에 이식한 결과, 실트함량, 유기물함량, 미생물현존량 및 토양중의 산화환원전위층은 시간의 경과와 함께 이식한 간석지의 토양구조와 동일하게 변이해 가는 것을 알았다. 또한 이식 토양중의 실트함량, 미생물현존량 및 유기물함량과는 높은 상관관계를 나타내었다. 실트함량 및 유기물함량의 증감과 함께 미생물현존량이 비례해서 증감하는 것을 알았다. 또한 실내실험 결과에서도 실트함량이나 유기물함량의 증가와 함께 미생물현존량이 증가하였다. 또한 그 원인은 실트함량이 증가함에 따른 결과라는 것을 알 수 있었다.

• 산경연구논집
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• 제9권10호
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• pp.51-61
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• 2018

Purpose - Korean women suffered from serious experience at unfair personnel practice in the work and coexistence between work and home affairs. The study examined woman workers' career plateau perception and success who worked for local public enterprises, that is to say, regional public corporation invested by local government, and investigated mediating effect of dual commitment as well as control effect of self-efficacy from point of view of various access to variables. Research design, data, and methodology - The study investigated women employees of regional public corporation by empirical analysis. The author collected 337 copies from 380 copies and made use of 325 copies after excluding copies with improper answer. SPSS 24.0 and AMOS 24.0 were used. Results - The study investigated effect of career plateau (structure and content) upon subjective career success (job satisfaction and career commitment) according to questionnaire material: First, not only structural plateau but also content career plateau had negative influence upon dual commitment (structure and career). Second, dual commitment had positive influence upon subjective career success from point of view of organizational commitment and career commitment. Third, structural career plateau had positive influence upon career success, and content career plateau had positive influence upon job satisfaction. Fourth, structural career plateau did not have significant influence upon job satisfaction, content career plateau and career satisfaction. Fifth, subordinate variables (organizational commitment and career commitment) had mediating influence upon career plateau cognition and subjective career success. Sixth, self efficacy did not control career plateau cognition and subjective career success. Conclusions - Women employee's career plateau cognition mediated dual commitment to have influence upon career success and to be likely to help career success theory study. Career plateau had negative influence upon dual commitment and career success of women workers. The study shall give base of counteraction from point of view of control and motivation of women workers thinking of career plateau.

• 한국결정성장학회지
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• 제17권5호
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• pp.217-222
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• 2007

[ $(1-x)CaWO_4-xYNbO_4$ ]계에 대하여 $YNbO_4(0.05{\leq}x{\leq}0.4)$의 치환량 변화에 따른 마이크로파 유전특성을 고찰하였다. x=0.10 조성까지 정방정(tetragonal) scheelite 구조의 $CaWO_4$ 단일상이 확인되었고, 그 이상 첨가 시 fergusonite 구조의 2차상이 증가하였다. $YNbO_4$ 첨가량이 증가할수록 겉보기 밀도는 감소하였는데, 이는 $CaWO_4(6.117g/cm^3)$보다 $YNbO_4(5.581g/cm^3)$가 더 낮은 이론밀도 값을 갖기 때문이다. $YNbO_4$의 첨가량이 증가함에 따라 유전상수(K)와 품질계수(Qf)는 2차상의 증가와 밀도의 감소로 인해 감소하는 경향을 보였고, $YNbO_4$ 치환량에 따른 소결시편의 공진주파수 온도계수(TCF)의 변화는 존재상의 유전체 혼합 법칙(dielectric mixing rule)에 의존하였다.

• 전자공학회논문지
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• 제50권9호
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• pp.77-84
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• 2013

빠르게 일어나는 기술의 발전과 그 안에 내재된 문화적 현상을 결합하려는 시도를 문화 컴퓨팅, 문화 모델링이라 한다. 본 논문에서는 문화 모델링 연구 추세를 기반으로 문화 사용자 인터페이스 디자인, 특히 그 중에서도 콘텐츠를 중심으로 한 문화 기반 디자인 구조를 설명한다. 문화에 기반한 콘텐츠를 디자인하기 위해서는 콘텐츠의 문화적 특성을 도출하는 구조가 필요하다. 이를 위해 Hofstede의 문화 차원 모델과 콘텐츠 데이터를 결합하여, 콘텐츠 중심의 문화 차원 지수(CiCo) 구조를 새롭게 제안한다. 또한 도출한 CiCo와 국가별 콘텐츠 선호 패턴을 결합하여 국가별 콘텐츠 문화 차원 지수인 NiCC를 도출한다. 제안하는 CiCo와 NiCC는 기존의 Hofstede 모델에 기반하였으되, 기존 모델 대비 약 10% 개선된 설명력을 갖는다.

• 한국주조공학회지
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• 제25권1호
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• pp.40-50
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• 2005

A series of heavy section ductile cast iron ingots with the cube length of 250mm were systematically investigated as functions of casting parameters of sand casting. Abnormal graphite formation was specially observed with the variation of Si content and Bi or Sb addition. Effects of chilling during casting and adaptation of riserless system were also examined, and proved to be effective for the prevention of both shrinkage and abnormal graphite such as chunky one. The formation of chunky graphite was effectively prevented by low Si content despite the promotion of pearlite matrix structure. The ferritic matrix was encouraged to form by high Si content and chunky graphite formation was effectively suppressed by the addition of Bi and Sb. Bi addition, however, was not good enough to control the microstructure owing to the sensitive cooling rate dependent inoculation behavior and relative low ability of nodulization. Sb addition, on the other hand, was proved to be effective for the microstructural control and enhancement of various mechanical properties such as strength, elongation, and impact energy. It may be suggested that optimized casting parameters should be applied to produce heavy section ductile cast iron with reliability.

• 한국문헌정보학회지
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• 제33권1호
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• pp.87-111
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• 1999

본고는 분류용 MARC 포맷에 대해 기능과 필요성, 개발현황에 대해 살펴보고, KORMARC 분류용포맷의 개발필요성을 제시하였다. 아울러 MARC포맷의 3요소로 일컬어지는 구조와, 내용표지법, 레코드의 내용을 이미 개발된 USMARC 포맷을 중심으로 분석하였다. 레코드의 구조와 내용표지법은 서지용 및 전거용포맷과 대부분 동일하다. 데이터필드는 기본적으로 기능별블록으로 구분되어 있다. 고정길이필드의 레코드의 내용에는 기호의 유형, 유효성, 표준 및 임의규정, 합성기호표시 등 분류기호에 관련된 요소들이 추가되어 있다. 가변길이필드의 내용은 번호와 코드 분류기호와 용어 참조 및 표목지시, 주기, 색인어, 기호합성, 전자상의 소재 및 접근 필드 등으로 구성되어 있다. 각 필드의 데이터들은 가능한 한 관련포맷과 조기성을 유지할 수 있도록 배려하고 있다.

• 한국도로학회논문집
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• 제18권1호
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• pp.63-72
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• 2016

PURPOSES : The use of roller-compacted concrete pavement (RCCP) is an environmentally friendly method of construction that utilizes the aggregate interlock effect by means of a hydration reaction and roller compacting, demonstrating a superb structural performance with a relatively small unit water content and unit cement content. However, even if an excellent structural performance was secured through a previous study, the verification research on the environmental load and long-term durability was conducted under unsatisfactory conditions. In order to secure longterm durability, the construction of an appropriate internal air-void structure is required. In this study, a method of improving the long-term durability of RCCP will be suggested by analyzing the internal air-void structure and relevant durability of roller-compacted concrete. METHODS : The method of improving the long-term durability involves measurements of the air content, air voids, and air-spacing factor in RCCP that experiences a change in terms of the kind of air-entraining agent and chemical admixture proportions. This test should be conducted on the basis of test criteria such as ASTM C 457, 672, and KS F 2456. RESULTS : Freezing, thawing, and scaling resistance tests of roller compacted concrete without a chemical admixture showed that it was weak. However, as a result of conducting air entraining (AE) with an AE agent, a large amount of air was distributed with a range of 2~3%, and an air void spacing factor ranging from 200 to $300{\mu}m$ (close to $250{\mu}m$) coming from PCA was secured. Accordingly, the freezing and thawing resistance was improved, with a relative dynamic elastic modulus of more than 80%, and the scaling resistance was improved under the appropriate AE agent content rate. CONCLUSIONS : The long-term durability of RCCP has a direct relationship with the air-void spacing factor, and it can be secured only by ensuring the air void spacing factor through air entraining with the inclusion of an AE agent.