• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.06a
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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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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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.

• Journal of Elementary Mathematics Education in Korea
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• v.16 no.3
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• pp.471-489
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• 2012

2007 Curriculum Revision adopted new Inquiry Activities in mathematical textbooks. So it is critical to analyze the problems of actual application of Inquiry activities in the classrooms. For this purpose, we analyzed the Inquiry activities of Measurement Area of the textbooks and find the appropriate solutions. Secondly, we develop the reorganization materials to fix and solve the existing problems found in the previous problem analysis, and apply the development materials and examine the effects afterwards. The results of the survey indicated that most of teachers are well aware of the importance of Inquiry Activities. However, many teachers answered that Inquiry activities does contain neither diverse strategic approaches nor solutions accommodating with various learning levels of students. The most difficult points to educate Inquiry Activities are that it is difficult to teach students based on individual learning level and that activities consist of mainly short answers that makes it difficult to do in-depth Inquiry Activities. Analyzing Inquiry Activities in the textbook shows that Inquiry Activities in some chapters were constructed as simple sentence questions or presented with the solving process in the questions themselves. The following application classes were implemented by partially taking advantage of the newly developed reorganization materials. Then, the effects were measured by before and after questionnaires, the survey to teachers, and the results of activities. The reorganization materials were effective at arousing the curiosity from students as well as enabling the natural ability-level driven classes.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2003.11a
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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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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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$\mu\textrm{m}$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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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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• v.8 no.4
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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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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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.

• Culinary science and hospitality research
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• v.4
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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.