• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 Handout for 2000 Inter. Machine Tool Technical Seminar
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• pp.19-27
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• 2000

High speed machining (HSM), specifically end milling and ball end cutting, is attracting interest in the die/mold or aerospace industries for the machining of complex 3D surfaces. HSM of difficult-to-cut materials such as die/mold steels, titanium alloys or nickel based superalloys generates the concentrated thermal/frictional damage at the cutting edge of the tool and rapidly decreases the tool life. Following a brief introduction on HSM and reated aerospace or die/mold work, the paper reviews published data on the effect of cutter/workpiece orientation and cutting environments on tool performance. First, experimental work is detailed on the effect of cutter orientation on tool life, cutting forces, chip formation, specific force and workpiece surface roughness. Cutting was performed using 8 mm diameter PVD coated solid carbide cutters with the workpiece mounted at an angle of 45 degree from the cutter axis. A horizontal downwards cutting orientation proveded the best tool life with cut lengths ∼50% longer than for all other directions (horizontal upwards, vertical downwards, vertical upwards). Second, the cutting environments were investigated for dry, flood coolant, and compressed chilly air coolant cutting. The experiments were performed for various hardened materials and various coated tools. The results show that the cutting environment using compressed cilly air coolant provided better tool life than the flood coolant or the dry.

• 한국기계가공학회지
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• 제11권1호
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• pp.7-12
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• 2012

Chemical mechanical polishing(CMP) technology is faced with the challenge of processing new electronic materials. This paper focuses on the balance between chemical and mechanical reactions in the CMP process that is required to cope with a variety of electronic materials. The material properties were classified into the following categories: easy to abrade(ETA), difficult to abrade(DTA), easy to react(ETR) and difficult to react(DTR). The chemical and mechanical balance for the representative ETA-ETR, DTA-ETR, ETA-DTR and DTA-DTR materials was considered for defect-free surfaces. This paper suggests the suitable polishing methods and examples for each electronic material.

• 한국초등수학교육학회지
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• 제16권3호
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• pp.471-489
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• 2012

2007 개정 교육과정에 따른 수학교과서에 처음으로 도입된 '탐구활동'이 어떻게 지도되고 있는가? 수학 탐구활동의 내용으로 적합하게 구성되어있는가? 수학적 탐구활동의 전제와 내용은 어떤 것이 좋은가? 이와 같은 문제에 답하기 위해 먼저 설문조사를 실시하여 탐구활동에 대한 교사들의 인식, 교육 현장에서의 지도 실태와 탐구활동 내용 및 유형의 적합성, 지도의 어려움과 재구성 자료의 필요성에 대해 알아보았다. 그리고 수학과 목표를 참고한 분석 기준을 설정하여 측정영역에서 교과서의 탐구활동을 분석하여 재구성할 필요가 있는 부분에 대해서는 대안을 제시하고 그 결과를 수업에 적용하여 학생들의 반응을 기술하였다.

• 한국식품영양과학회:학술대회논문집
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• 한국식품영양과학회 2003년도 정기총회 및 54차 학술발표회:건강기능식품의 유효성평가
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• pp.74-77
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• 2003

A new health paradigm may be evolving that would place emphasis on the positive aspects of diet, identifying components that are physiologically active and that contribute to the prevention of disease onset. It has been increasingly difficult to evaluate the impact of new bioactive materials and food products on the well being of society. Thus, testing systems for both health function and toxicity have become very elaborate, complex, and interrelated, making their interpretation difficult and open to controversy. To select the proper starting materials, to screen the appropriate health functionality and to determine the efficacy of product, a reliable, reproducible, sensitive and predictive assay is required. Particularly, in uitro assay is the first stage in preclinical test on physiologically active materials and have many advantages in terms of time, cost and convenience. However, several factors as well as some limitations should be considered in this assay system. This presentation, therefore, will address the use of in uitro assays for evaluating physiological functionality of foods coupled with general consideration.

• 한국기계가공학회지
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• 제3권2호
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• pp.3-9
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• 2004

The main objectives of this paper are to determine optimum cutting conditions using experimental design method to manufacture pedicle screws. Generally, titanium alloys are known as difficult-to cut materials. In the machining of titanium alloy, high cutting temperature and strong chemical affinity between the tool and the work material are generated because of Its low thermal conductivity and chemical reactivity. Such phenomenon cause increase of tool wear and deterioration of surface quality. Thus, in this paper, required experimental investigations are performed to evaluate the machinability of titanium materials With tungsten carbide tools Required simulation and experiments are performed, and the results are investigated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.808-811
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• 1997

MMC has excellent mechanical properties in many ways in automotive industrial, and get into the spotlight as a light materials substituted for iron and steel. But the know-how about MMC research lack, MMC is expensive and difficult to apply the sound parts. Especially it is difficult to produce the hollow type parts composed with MMC. Therefore, hollow type parts of metal composites by using thixoforming process which as co-existing solidus-liquidus phase, it is very important to obtain forming condition. In this study, MMC billet producted by electro-magnetic stirring and mechanical stirring process is formed to hollow type parts of thixoforming process and inspected of suitability for application. It is optimized production condition, and applied to experiment. After variable materials were produced for thixoforming process, it were inspected of suitability for application by comparsion with mechanical properties. In this study, used materials were A357, A380 10%vol, and 20%vol SiCp, and the size of particultes were 14$\mu\textrm{m}$ and 5.5$\mu\textrm{m}$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.291-295
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• 2002

Ceramics are very difficult-to-cut materials because of its high strength and hardness. Their machining process can be characterized by cracking and brittle fracture. Generally, ceramics are machined using traditional method such as grinding and polishing. However, such processes are generally costly and have low material removal rate. In this paper, to develop machinable ceramics those have good machinability without losing their material properties, machinability evaluations are performed by applying the experimental design method. In this paper, to evaluate the machinability of the developed ceramics, various workpieces are machined on the CNC machining center, and surface roughness are measured under predefined process parameters obtained using Taguchi method. And the experimental results are investigated to derive optimum cutting parameters for the given materials.

• International journal of advanced smart convergence
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• 제8권4호
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• pp.40-46
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• 2019

The current education is becoming more extensive with the application of various teaching methods. This is a problem that is so distributed that it is difficult for users to find the data and it takes a long time to find the information they need. Currently, various educational services, materials, and instruments are developed and scattered. Therefore, it is important to raise students' awareness of aptitude and career path with customized education tailored to students. Conventional education platforms have very difficult to choose the right materials for students because of the spread of educational programs and institution materials. To solve this, we propose a customized recommendation approach to recommend customized educational service materials and institution for students to teachers, which helps teachers conveniently choose materials suitable for their respective environments. On this new platform, the CNN algorithm provides recommended content for classes and students. For real service on the educational service platform, we implement this system for Jeil edus business. Through this mechanism, we expect to improve the quality of education by helping to select the right service.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.50-51
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• 2020

Recently, various maintenance materials and construction methods have been developed to secure the sustainable performance of structures. However, waterproofing of underground structures where groundwater infiltration is present is very difficult. In particular, the location of underground structures such as subways is very deep, and it is difficult to apply waterproof materials and construction methods in the case of structures accompanied by vibration. Therefore, we intend to study materials and methods for waterproofing leakage resistance in special environments such as underground structures.

• 한국조리학회지
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• 제4권
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• pp.389-411
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• 1998

The consumption of bread as the principal food is increasing. The taste of bread depends on the components of raw materials. Though the knowledge about the raw materials of bread is important for the development of new products and the cost accounting, it is difficult to find the study on the role of raw materials in making bread. Therefore, the purpose of this study is to integrate the existing theoretical study on bread. Then, it will provide the basic knowledge on the raw materials in making bread in order to develop the technique of making bread.