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하이브리드 외부가압 공기베어링에서 노즐 위치에 따른 부하지지력 특성
이득우,이종렬,황성철,이준석 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-
Externally pressurized air journal bearing has been widely used in high-speed spindle system and precision machinery because of its characteristics such as substantially low frictional loss, low heat generation and averaging effect leading better running accuracy. But air journal bearing have a disadvantage of the low load capacity due to the low viscosity. In this paper. The air journal bearing design to overcome the defects of air bearing such as low stiffness and dimping coefficients was investigated theoretically.
시계열 데이터와 랜덤 포레스트를 활용한 시간당 초미세먼지 농도 예측
이득우,이수원,Lee, Deukwoo,Lee, Soowon 한국정보처리학회 2020 정보처리학회논문지. 소프트웨어 및 데이터 공학 Vol.9 No.4
최근 환경 문제에서 중요한 화두로 떠오른 초미세먼지(PM2.5)는 미세먼지(PM10)보다도 작은 부유물질이다. PM2.5는 안구나 호흡기 질환을 일으키며 뇌혈관에까지 침투할 수 있어서 시간별로 수치를 예측하여 대비하는 것이 중요하다. 그러나 PM2.5의 생성과 이동에 관한 명확한 설명이 아직까지는 제시되지 않고 있어서 예측에 어려움이 따른다. 따라서 PM2.5 예측뿐만 아니라 예측 결과에 대한 설명력을 갖는 예측 방법이 제시될 필요가 있다. 본 연구에서는 서울시의 시간당 PM2.5를 예측하고자 하며, 이를 위해 각기 다른 지상관측 데이터를 시계열로 전처리하고 부트스트랩수를 조정한 랜덤 포레스트(Random Forest)를 데이터 학습 및 예측에 사용하는 방법을 제안한다. 이 방법은 예측 모델이 입력 데이터의 시각별 정보를 균형 있게 학습하게 하며 예측 결과에 대한 설명이 가능하다는 장점을 갖는다. 예측 정확도 평가를 위해 기존 모델과의 비교실험을 수행한 결과 제안 방법은 모든 레이블에서 가장 뛰어난 예측 성능을 보였으며, PM2.5의 생성과 관련된 변수와 중국의 영향과 관련된 변수가 예측 결과에 중요한 영향을 미치는 것을 보여주었다. PM2.5 which is a very tiny air particulate matter even smaller than PM10 has been issued in the environmental problem. Since PM2.5 can cause eye diseases or respiratory problems and infiltrate even deep blood vessels in the brain, it is important to predict PM2.5. However, it is difficult to predict PM2.5 because there is no clear explanation yet regarding the creation and the movement of PM2.5. Thus, prediction methods which not only predict PM2.5 accurately but also have the interpretability of the result are needed. To predict hourly PM2.5 of Seoul city, we propose a method using random forest with the adjusted bootstrap number from the time series ground data preprocessed on different sources. With this method, the prediction model can be trained uniformly on hourly information and the result has the interpretability. To evaluate the prediction performance, we conducted comparative experiments. As a result, the performance of the proposed method was superior against other models in all labels. Also, the proposed method showed the importance of the variables regarding the creation of PM2.5 and the effect of China.
니켈계 합금의 볼엔드밀 가공에서 절삭 방향에 따른 영향
이득우,Lee, Deuk-U 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.10
High speed ball end milling is attracting interest in the aerospace industry for the machining of complex 31) airfoil surfaces in nickel based superalloys, Experimental work is detailed on the effect of cutter orientation on tool life, cutting forces, chip formation, specific force and workpiece surface roughness, when high speed ball end milling nickel based supperalloy(lnconel 718). Dry cutting was performed using 8min diameter solid carbide cutters coated with either TiA1N or CrN for the workpiece mounted at an angle of 45˚ from the cutter axis. A horizontal downwards cutting orientation provided the best tool life with cut lengths~50% longer than for all other directions. Evaluation of cutting forces and associated spectrum analysis of results indicated that cutters employed in a horizontal downwards direction produced the least vibration.
$(Mg_{0.93}Ca_{0.07})TiO_3$ 세라믹스의 소결 및 마이크로파 유전특성에 미치는 $B_2O_3$의 영향
이득우,박재환,김인태,박재관,김윤호,최덕균 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.3
The effects of B2O3 addition on the sintering behavior and th microwave dielectric properties of $(Mg_{0.93}Ca_{0.07})TiO_3$ ceramics were investigated. By addition of $B_2O_3$, increases the density of the ceramics increases and grain growth enhances, It was densified to over 94% of $(Mg_{0.93}Ca_{0.07})TiO_3$ theoretical density by the addition of 0.15-1.0wt% B2O3 and stable microwave dielectric properties observed by the addition of 0.2-0.4wt% $B_2O_3.\;(Mg_{0.93}Ca_{0.07})TiO_3$ ceramics sintered at $1200^{\circ}C$ exhibits maximum dielectric constants of 24-25 quality factor($Q{\times}f$) of more than 70000 and temperature coefficient of resonant frequency of $0\;ppm/^{\circ}C$ by adding of 0.15-0.4wt% $B_2O_3$.
Toms 효과가 있는 저어널베어링에서의 $K-\epsilon$ 모델을 이용한 성능해석
이득우,김경웅 대한기계학회 1986 대한기계학회논문집 Vol.10 No.4
본 연구에서는 K-.epsilon. 모델을 사용하여 마찰감소 현상이 있는 저어널베어링 내 의 흐름을 해석하였다.
컴퓨터 비전 알고리즘을 기반으로 한 마이크로 드릴의 진직도 오차 측정
이득우,시티 누르파디라 빈티 자이니 한국생산제조학회 2022 한국생산제조학회지 Vol.31 No.2
Microdrill machining is widely applied in various industries where structural design and material properties of the microdrill play a critical role during the machining. A composite microdrill composed of WC and polycrystalline diamond combines the wear resistance, toughness, and hardness properties of the cutting tool. However, composite microdrills are fabricated through complex processes which make them prone to geometrical errors. Hence, axial straightness error of microdrills was investigated in this study as a geometrical error. A computer vision algorithm was specifically developed for measuring the axial straightness error of the microdrill. Subsequently, the ability of the developed technique to perform precise and accurate measurement of tool geometrical errors was evaluated in this study.