• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.303-306
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• 1997

In the case of a cooled air cooling applied to angular contact ball bearings in a high speed spindle unit,the heat generated heat in bearings is removed and the temperature of inner ring is decreased.. Therefore it is possible to increase the speed of spindle units.

• 대한수학회논문집
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• 제32권4호
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• pp.991-997
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• 2017

We classify the extreme, exposed and smooth symmetric 3-linear forms of the unit ball of ${\mathcal{L}}_s(^3l^2_{\infty})$, respectively.

• 대한수학회보
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• 제29권2호
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• pp.285-293
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• 1992

• Kyungpook Mathematical Journal
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• 제54권3호
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• pp.341-347
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• 2014

We classify the exposed symmetric bilinear forms of the unit ball of $\mathcal{L}_s(^2d_*(1,{\omega})^2)$.

• 대한수학회논문집
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• 제36권4호
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• pp.651-669
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• 2021

In this paper, we investigate some basic results on the slice regular Besov spaces of hyperholomorphic functions on the unit ball 𝔹. We also characterize the boundedness, compactness and find the essential norm estimates for composition operators between these spaces.

• 대한수학회보
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• 제56권2호
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• pp.319-331
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• 2019

On the weighted Dirichlet space, by the Sobolev's embedding theorem, we characterize the compactness for operators which are finite sums of products of several Toeplitz operators. Moreover, the essential spectrum of Toeplitz operator is characterized.

• 충청수학회지
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• 제34권3호
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• pp.307-316
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• 2021

We provide a gap theorem of Simons' type for free boundary minimal and constant mean curvature surfaces in the unit ball in 3-dimensional Euclidean space.

• 한국결정성장학회지
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• 제14권4호
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• pp.129-134
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• 2004

본 연구에서는 기계적 합금화(MA)에 의한 고상-기상반응에 있어서 질소원자가 V-Fe계 합금의 비정질화에 미치는 영향을 조사하였다. 유성형 볼밀을 사용하여 $V_{70}Fe_{30}$혼합분말을 질소가스 분위기 중 MA 처리하였다. 그 결과 160시간 MA 처리에 의하여 비정질상이 생성됨을 알 수 있었다. 160시간 동안 MA 처리한 ($V_{70}Fe$_{30}$)_{0.89}N_{0.11}$ 분말시료의 열분석 결과 약 $600^{\circ}C$에 비정질상의 결정화에 의한 발열 peak가 관찰되었다. 또한 bcc 결정에서 비정질상으로의 구조변화 과정을 X선 및 중성자 회절법을 통하여 조사하였으며, 특히 중성자회절에서는 V원자의 중성자에 대한 간섭성 핵산란진폭이 매우 작은 특징을 이용하였다. 그 결과, 이 합금계에서의 비정질화는 모든 결정구조에서 전형적으로 존재하는 8면체 unit가 우선적으로 붕괴되어 4면체 unit로 변환되어 가는 과정임을 알 수 있었다. 또한 중성자 회절에 의한 구조해석 결과 질소원자는 V원자로 이루어진 다면체의 중심에 위치하고 있음을 알 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.84-89
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• 2014

Data-driven method for fault diagnostics system often use machine learning technique. To use such technique proper signal processing should be implemented such as time synchronous averaging (TSA) for ball bearing systems. However, for journal bearing diagnostics systems not much has been researched, and yet a proper signal processing method has not been studied. Therefore, in this research an optimal datum unit for a reliable journal bearing diagnostics system along with angular resampling process is being suggested. Before extracting time and frequency domain features, angular resampling is applied to each cycle of vibration data. As to preserve the characteristics of vibration signal, averaging method is replaced by finding the optimal datum unit which strengthens statistical characteristics of vibration signal. Then 20 features were extracted for various cases, and those features are being evaluated by two criteria, separability and classification accuracy.

• The Korean Journal of Physiology
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• 제1권1호
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• pp.91-101
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• 1967

The maximal oxygen intake (MOI) was determined in 54 males (23 nonathletes, 10 basketball players, 8 hand ball players, 7 weight lifters and 6 long distance runners) and in 49 females (24 non-athletes, 16 basketball players and 9 volley ball players) by using a treadmill method outlined in Part I of the present investigation and the following results were obtained: (1) The maximal aerobic work capacity varied from the lowest value of 1,008 kg-m/min in female non-athletes to the highest value of approximately 2,000 kg-m/min in male basketball players and long distance runners. Values of other groups varied from 1,400 kg-m/min in male non-athletes and female athletes to 1,800 kg-m/min in male hand ball players. (2) The MOI per unit body weight varied from the lowest value of 41.3 ml/min/kg in female non-athletes to the highest value of 67.6 ml/min/kg in male long distance runners. Values of other groups were in the order of 47 to 55 ml/min/kg. (3) The heart rate during maximal aerobic work performance varied from the lowest value of approximately 180 per min in female basketball players and male long distance runners to the highest value of 190 or above in nonathletes of both sexes. (4) An estimate of oxygen debt as measured during 15 minutes following the maximal work was 3.841 in female non-athletes, 4.681 in female athletes, 5.561 in male non-athletes and 6.321 in male athletes. These results indicate that the MOI per unit body weight as well as the oxygen debt of Korean non-athletes were comparable to, while corresponding values of Korean athletes were considerably lower than, those of other countries such as Japan, the United States of America and Europe.