• 대한수학회지
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• 제46권5호
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• pp.1087-1103
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• 2009

Given a system of s independent 1-forms on a smooth manifold M of dimension m, we study the existence of integral manifolds by means of various generalized versions of the Frobenius theorem. In particular, we present necessary and sufficient conditions for there to exist s'-parameter (s' < s) family of integral manifolds of dimension p := m-s, and a necessary and sufficient condition for there to exist integral manifolds of dimension p', p' $\leq$ p. We also present examples and applications to complex analysis in several variables.

• 대한수학회보
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• 제58권2호
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• pp.497-505
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• 2021

Let R → S be a ring homomorphism. The relations of Gorenstein projective dimension with respect to a semidualizing module of homologically bounded complexes between U ⊗LR X and X are considered, where X is an R-complex and U is an S-complex. Some sufficient conditions are given under which the equality ${\mathcal{GP}}_{\tilde{C}}-pd_S(S{\otimes}{L \atop R}X)={\mathcal{GP}}_C-pd_R(X)$ holds. As an application it is shown that the Auslander-Buchsbaum formula holds for GC-projective dimension.

• 대한수학회보
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• 제61권3호
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• pp.735-744
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• 2024

In this note, we shed new light on Krull domains from the point view of Gorenstein homological algebra. By using the so-called w-operation, we show that an integral domain R is Krull if and only if for any nonzero proper w-ideal I, the Gorenstein global dimension of the w-factor ring (R/I)_w is zero. Further, we obtain that an integral domain R is Dedekind if and only if for any nonzero proper ideal I, the Gorenstein global dimension of the factor ring R/I is zero.

• 보건의료산업학회지
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• 제8권3호
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• pp.193-205
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• 2014

The purpose of this study is to find out the effects of the socio-demographic characteristics, self-recognition factors, and health behavior factors of Korean adolescents on suicide dimension, and grasp the effects of suicide thinking of adolescents on attempting suicide. This study used the eighth primitive data of the "Web-based Survey on Adolescents Health Behavior(2012)", and targeted 72,228 actual test respondent(93.8%). In conclusion, risk factors that greatly influence the suicide dimension of adolescents can be summarized into level of happiness, level of stress, depression, experience drinking, experience smoking, experience with drugs, suicide thinking, etc. and considering these risk factors, a preparation for preventing adolescents' suicide should be established, and along with a regular education, developing and expanding a treatment program for preventing recurrence afterwards of adolescents who have experience attempting suicide are necessary.

• Communications for Statistical Applications and Methods
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• 제19권4호
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• pp.559-569
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• 2012

Compositional data consist of compositions that are non-negative vectors of proportions with the unit-sum constraint. In disciplines such as petrology and archaeometry, it is fundamental to statistically analyze this type of data. Aitchison (1983) introduced a log-contrast principal component analysis that involves logratio transformed data, as a dimension-reduction technique to understand and interpret the structure of compositional data. However, the analysis is not usable when zero values are present in the data. In this paper, we introduce 4 possible methods to reduce the dimension of compositional data with zero values. Two real data sets are analyzed using the methods and the obtained results are compared.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.34-38
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• 2003

In metal working, cold forging that has profit to satisfy dimension accuracy is using in various manufacturing products. Recently, most of the interest thing is precision forging of gear. Gear forging product is more strength than broaching gear, and it has many advantages with reduction of factory expenses. The reason of difficulty to improve accuracy of gear dimension compare to another products is the dimension accuracy is very high, approximately 10$\mu\textrm{m}$, and because die of involute teeth and elastic strain of forged tool differ from standard curve. This paper represent quantitative analysis of die and teeth of forged tool, namely difference of curves, with experiments and analyze the factor of dimension gap, finally, will design compensated involute curve.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.29-33
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• 2003

The improvement of dimensional accuracy for forged part is one of major goals in cold forging industry. There are many problems in controlling the dimension only by the trial-and-error, especially for a precision forged gear. A FEM analysis has been used in developing the forging technology. However, FE techniques have to be reconfirmed for predicting accurately the dimension of forged part. In this study, the effects of elastic characteristics and temperature changes are investigated by the comparisons between experimental and FEA in cold forging. When FE models related with elastic characteristics are considered as reality, FE results could predict the part dimension within the range of 10 $\mu\textrm{m}$. And if temperature also is considered really, the predicted dimensions are well coincided with the experimental down to about 5$\mu\textrm{m}$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.605-611
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• 2001

A numerical technique for simulating the aggregation of charged particles was presented with a Brownian dynamic simulation in the free molecular regime. The Langevin equation was used for tracking each particle making up an aggregate. A periodic boundary condition was used for calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered the thermal force and the electrostatic force for the calculation of the particle motion. The morphological shape of aggregates was described in terms of the fractal dimension. The fractal dimension for the uncharged aggregate was $D_{f}=1.761$. The fractal dimension changed slightly for the various amounts of bipolar charge. However, in case of unipolar charge, the fractal dimension decreased from 1.641 to 1.537 with the increase of the average number of charges on the particles from 0.2 to 0.3 in initial states.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 센서 박막재료
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• pp.47-51
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• 2001

The structural properties of varistors surface studied by fractal phenomenon were investigated to verify the relations of electrical characteristics. The SEM photograph of varistors surface were changed by binary code and the grain shape of that were analyzed by fractal dimension. The void of varistors surface was found by fractal program. The relation between grain density and electrical properties depend on fractal dimension. The grain size in varistors surface was decreased by increasing of oxide antimony addition. The grain size of devices by oxide antimony addition were from 5 to $10[{\mu}m]$. The fractal dimension and electrical properties of varistors surface was related to between grain boundary and grain density. The grain size was decreased by increasing of fractal dimensions.

• 전자공학회논문지B
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• 제33B권3호
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• pp.169-175
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• 1996

In this paper, a new parallel neural network system that performs dynamic competitive learning is proposed. Conventional learning mehtods utilize the full dimension of the original input patterns. However, a particular attribute or dimension of the input patterns does not necessarily contribute to classification. The proposed system consists of parallel neural networks with the reduced input dimension in order to take advantage of the information in each dimension of the input patterns. Consensus schemes were developed to decide the netowrks performs a competitive learning that dynamically generates output neurons as learning proceeds. Each output neuron has it sown class threshold in the proposed dynamic competitive learning. Because the class threshold in the proposed dynamic learning phase, the proposed neural netowrk adapts properly to the input patterns distribution. Experimental results with remote sensing and speech data indicate the improved performance of the proposed method compared to the conventional learning methods.