• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1691-1701
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• 2006

The scan type magnetic camera is proposed to improve the limited spatial resolution due to the size of the packaged magnetic sensor. An image of the scan type magnetic camera, ${\partial}B/{\partial}x$ image, is useful for extracting the crack information of a specimen under a large inclined mag netic field distribution due to the poles of magnetizer. The ${\partial}B/{\partial}x$ images of the cracks of different shapes and sizes are calculated by using the improved dipole model proposed in this paper. The improved dipole model uses small divided dipole models, the rotation and relocation of each dipole model and the principle of superposition. Also for a low carbon steel specimen, the experimental results of nondestructive testing obtained by using multiple cracks are compared with the modeling results to verify the effectiveness of ${\partial}B/{\partial}x$ modeling. The improved dipole model can be used to simulate the LMF and ${\partial}B/{\partial}x$ image of a specimen with complex cracks, and to evaluate the cracks quantitatively using magnetic flux leakage testing.

• 한국정밀공학회지
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• 제30권11호
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• pp.1193-1201
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• 2013

Improved far field type(improved type) megasonic applicable to the cleaning equipment of single wafer processing type has been developed. In this study, to improve the uniformity of acoustic pressure distribution(APD), we utilize far field with relatively uniform APD, piezoelectric ceramic with a triangle hole in its center to prevent standing wave resulted from radial mode, and reflected wave from the wall of waveguide. On the basis of these methods, two analysis models of improved type were designed to which piezoelectric ceramic of different shape of electrode attached, and APD were analyzed by means of finite element method, and then one of them was selected by analysis results, finally, the selected model was fabricated. Test results show that the fabricated is better in the uniformity of APD than the imported and the conventional, also the fabricated shows high particle removal efficiency of 92.3% using DI water alone as a cleaning solution.

• 호남수학학술지
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• 제26권2호
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• pp.219-236
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• 2004

In this paper, the problem of estimating a p-variate ($p{\geq}4$) normal mean vector is considered in a decision-theoretic setup. Using a simple property of the noncentral chi-square distribution, a sequence of smooth estimators dominating the Lindley type estimator has been produced and each improved estimator is better than previous one.

• Journal of the Korean Data and Information Science Society
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• 제13권2호
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• pp.11-19
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• 2002

In this paper, the problem of estimating a p-variate $(p\geq4)$ normal mean vector in a decision-theoretic setup is considered. Using a technique of Guo and Pal (1992), a sequence of estimators dominating the Lindley type estimator is derived and each improved estimator is better than the previous one.

• 충청수학회지
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• 제22권2호
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• pp.171-175
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• 2009

Let $A_1,\;A_2,\;{\cdots},\;A_n$ be a sequence of events on a given probability space. Let $m_n$ be the number of those $A_{i}{^{\prime}}s$ which occur. We establish an improved lower bounds of Univariate Bonferroni-Type inequality by using the linearity of binomial moments $S_1,\;S_2,\;S_3,\;S_4$ and$S_5$.

• 한국자동차공학회논문집
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• 제10권5호
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• pp.121-128
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• 2002

In this paper, the fuel economy of plug-in type hybrid electric vehicle is investigated through simulation. For the simulation study, 2 shaft type parallel hybrid powertrain is chosen and its operation modes are described. The operation algorithm which yields operation points of minimal fuel cost is suggested. Dynamic model fur operation of HEV and simulation procedure is described. Simulation results of fuel economy is compared to non plug-in type HEV as well as conventional vehicle. With total driving distance of 37km and full usage of 2kwh of electric energy stored in battery pack, plug-in type HEV shows 28-30% improved fuel economy compared to non plug-in type HEV and 86-93% improved fuel economy compared to conventional vehicle.

• Journal of Power Electronics
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• 제17권4호
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• pp.874-883
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• 2017

T-type isolated DC/DC converters have recently attracted attention due to their numerous advantages, including few components, low cost, and symmetrical operation of transformers. This study proposes an improved control strategy for increasing the efficiency of T-type isolated DC/DC converters. Under the proposed strategy, the primary circulating current flows through the auxiliary switches (metal-oxide-semiconductor field-effect transistors) instead of their body diodes in free-wheeling periods. Such feature can reduce conduction losses, thereby improving the efficiency of T-type isolated DC/DC converters. The operation principles and performances of T-type isolated DC/DC converters under the proposed control strategy are analyzed in detail and verified through the simulation and experimental results.

• 한국식품과학회지
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• 제53권6호
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• pp.815-818
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• 2021

The objective of this study was to develop a differential medium with improved selectivity for the isolation of Bacillus cereus. Mannitol egg yolk polymyxin medium supplemented with D-galactose allowed the differentiation of diarrheal- and emetic-type B. cereus through pH monitoring. The pH of the medium decreased significantly when incubating the emetic-type B. cereus, whereas the pH change was not significant when incubating the diarrheal-type. The addition of pH indicators, such as methyl red and phenol red, to the medium allowed visual differentiation between diarrheal- and emetic-type B. cereus. A solid agar medium was also developed by optimizing the concentrations of medium components such as monosaccharides, agar, egg yolk enrichment, pH indicators, and antibiotics. This study indicates the possibility of applying selective media for the differentiation of diarrheal- and emetic-type B. cereus.

• 한국도로학회논문집
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• 제16권1호
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• pp.99-109
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• 2014

PURPOSES : Climbing lanes on expressways managed by the Korea Expressway Corporation (KEC) have been hot potatoes due to conflicts between slow-moving vehicles such as trucks and other vehicles at the merging section as well as the less popularity with the slow-moving vehicles. In order to resolve such problems, KEC has altered existing climbing lanes to passing-type climbing lanes in 1999. The new type of climbing lanes showed an apparent improvement in mobility. For example, the speeds of vehicles using both climbing lane and other lanes improved a lot. However, there has been no clear evidence about improved safety. METHODS : This research effort was initiated to evaluate the safety of the new passing-type climbing lanes using the comparison-group(CG) method based on three-year-long traffic accident data sets before and after the change, respectively. RESULTS : The passing-type climbing lanes showed twice increased traffic accidents even though the traffic accidents on old type climbing lanes increased 1.1% during the same periods. In addition, in-depth study, the merging area of the passing-type climbing lanes was found out to be the weakest section where 43.8% traffic accidents out of total traffic accidents happened. It is noted that the merging area of the old type climbing showed only 25.0% traffic accidents. CONCLUSIONS : The new passing-type climbing lanes were found to be weak in terms of safety when compared with the old type climbing lanes. Especially, the merging area should be improved to reduce the risk of traffic conflicts between slow-moving vehicles and other vehicles.

• 가정과삶의질연구
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• 제11권1호
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• pp.35-45
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• 1993

The purpose of this study is to investigate the changes of housing characteristics and the degree of attainment of housing norms. The major findings are as follows: 1) There are significant differences in changes of housing characteristics. A size of house and the number of room have been improved according to hosing experience and housing expects. Type of tenure has been improved according to housing experience and housing expects. Type of tenure has been improved gradually according to moving. The family with higher socio-economic status prefers apartments. Although about a half of household hopes to live in a high-rising apartments. more than 40 persentage of the household still hopes to live in single detached houses. As a result apartment are though not to satisfy their housing well-being 2) As socio-economic status is higher and family life cycle is longer the degree of their attainment of housing norms appear higher. The household attaining higher housing norms has the higher housing satisfaction but needs to move is lower The family attains housing norms as the following orders: type of tenure\longrightarrowtype of house\longrightarrowthe nmber of rooms\longrightarrowa size of house.