• 소성∙가공
• /
• 제6권2호
• /
• pp.95-101
• /
• 1997

The thermal fatigue and wear properties of high speed steel roll which was recently developed were investigated by observing microstructure, by measuring mechanical and physical properties, by conducting thermal fatigue testing, and by measuring the amount of wear in actual mill. High speed steel roll had better thermal fatigue testing, and by measuring the amount of wear in actual mill. High speed steel roll had better thermal fatigue life than high chromium iron roll, which was due to lower carbide content, higher strength, and higher thermal conductivity. The amount of wear of high speed steel roll was nearly the same as that of high chromium iron roll in the first finishing stand, which was due to the oxide formation on the roll surface. However, in the third finishing stand, the wear resistance of high speed steel roll was 2~3 times as good as that of high chromium iron roll because the former had higher hardness at high temperature.

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2018년도 추계학술논문요약집
• /
• pp.569-570
• /
• 2018

• 천문학회보
• /
• 제41권1호
• /
• pp.63.4-64
• /
• 2016

본 발표에서는 DSLR 카메라와 CCD를 이용하여 과학고등학교의 R&E교육과정에서 수행한 몇 가지 실험과 그 결과를 소개한다. DSLR 카메라와 SQM을 이용한 밤하늘 특성 분석, CCD를 이용한 고유운동 측정, DSLR을 이용한 산개성단의 측광, CCD를 이용한 산개성단의 측광과 이를 통한 산개성단의 질량분리와 역학적 진화에 대한 연구이다. 실험은 부산일과학고, 울산과학고, 부산과학고에서 수행되었으며, 모든 실험의 결과는 학생들이 직접 관측한 결과를 바탕으로 이루어졌다. 본 실험의 방법과 과정은 일선 학교에서 응용하여 활용될 수 있으며, 실험의 결과는 향후 유사한 실험 교육을 수행할 때 기초 자료로 활용되어 질 수 있다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
• /
• pp.63-68
• /
• 1998

The fluidity of high flowing concrete can be affected by numerous parameters which characterize either the cement of the admixture. The reactivity of a cement as determined by its chemical composition(especially its $C_3$A content), its fineness and its content in sulfates and alkalies obviously plays a key role in rheology of high flowing concrete in fresh state. Specific properties of high range water reducing AE agent used to enhance the workability of high flowing concrete also exert important influence. The purpose of this experimental study is to investigate and analyze the effect of cement and high range water reducing AE agent in fluidity, setting, compressive strength of high flowing concrete. As a result, we found that fluidity of high flowing concrete is affected greatly by kind of cement and high range water reducing AE agent, also, there is harmonic character between high belite cement and polycarbonic acid high range water reducing AE agent.

• Journal of Preventive Medicine and Public Health
• /
• 제56권5호
• /
• pp.475-480
• /
• 2023

Objectives: This study examined differences in health care spending and characteristics among older adults in Korea by high-cost status (persistently, transiently, and never high-cost). Methods: We identified 1 364 119 older adults using data from the Korean National Insurance Claims Database for 2017-2019. Outcomes included average annual total health care spending and high-cost status for 2017-2019. Linear regression was used to estimate differences in the outcomes while adjusting for individual-level characteristics. Results: Persistently and transiently high-cost older adults had higher health care spending than never high-cost older adults, but the difference in health care spending was greater among persistently high-cost older adults than among transiently high-cost older adults (US$20 437 vs. 5486). Despite demographic and socioeconomic differences between transiently high-cost and never high-cost older adults, the presence of comorbid conditions remained the most significant factor. However, there were no or small differences in the prevalence of comorbid conditions between persistently high-cost and transiently high-cost older adults. Rather, notable differences were observed in socioeconomic status, including disability and receipt of Medical Aid. Conclusions: Medical risk factors contribute to high health care spending to some extent, but social risk factors may be a source of persistent high-cost status among older adults in Korea.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 춘계학술대회 논문집
• /
• pp.439-444
• /
• 2004

The important problem in high speed spindle is to reduce and minimize the thermal effect by motor and ball bearings. In this study. the effects of bearing preload and cooling for high speed spindle with high frequency motor are investigated. A high speed spindle is composed of angular contact ball bearings, high frequency motor, grease lubrication, oil jacket cooling, and so on. Heat generation of the bearing and the high frequency motor are estimated from the theoretical and experimental data. The thermal analyses of high speed spindle to minimize the thermal effect and maximize the cooling effect are carried out under the various cooling conditions and preload. Method of variable bearing preload and cooling can be useful to design the high speed motor spindle. The results show that the optimal preload and cooling are very effective to minimize the thermal displacement by motor and ball bearing.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.616-620
• /
• 2005

The technology of high-speed electrical machines is particularly relevant to applications involving electrical power generation and high-speed motors with high power density and high efficiency. Due to the development of improved materials for electrical machines, power electronic elements and design technology, the high-speed electrical machines are being rapidly introduced into industrial applications. The introduction of high-speed electrical machines has created a new market for electrical machines and will, as an application, contribute to the development of modern electrical machines. This paper deals with applications and market trends and KERI's activities in high-speed electrical machines.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2008년도 추계 학술논문 발표대회
• /
• pp.107-111
• /
• 2008

As high-rise buildings with 100 or more stories are being constructed, it is inevitable to use high-performance materials including high-performance concrete. What is most important in high-performance concrete is extremely high strength in order to reduce the section of members in high-rise buildings. During the last several years, there have been active researches on Ultra-high-strength concrete. While these researches have been mostly focused on strength development, however, other accompanying physical properties have not been studied sufficiently. Thus, this study purposed to obtain and analyze data on the physical-mechanical properties of Ultra-high-strength concrete through experiments and to use the results as basic information on required performance of concrete used in high-rise buildings.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
• /
• pp.221-226
• /
• 1999

It can be acquired the high effective productivity through of high speed, precision of machine tools, and then, machine tools will be got a competitive power. Industrially advanced countries already developed that the high speed feed is 50m/min using the high speed ball screw. Also, a lot of problems have happened the feed and servo drive system. It is necessary to study about the character of positioning accuracy, heat generation and high speed/accuracy control for feed/servo drive system of high speed/accuracy. In this study, we make use of high performance vertical machine center with a ball screw of large-scale-lead. Also, we'll apply the high-speed/accuracy control technology in this part of feedforward control, multi-buffering block size, etc. Using the design of the mechanical element and high-speed precision control, the basic design concept can be established.

• 음성과학
• /
• 제9권4호
• /
• pp.105-110
• /
• 2002

This study compared nasalance in low pressure and high pressure consonants and high and low vowels. The subjects were 8 children with cleft palate ranging from 3 years 6 months to 8 years in age. The measurement were taken in terms of the nasalance scores associated with 20 different word stimuli (high consonants+high vowels, high consonants+low vowels, low consonants+high vowels, and low consonants+low vowels) for subjects. The nasalance scores may be affected by high consonants and vowels types, low vowels and consonants types.