• Journal of electromagnetic engineering and science
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• 제1권1호
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• pp.43-47
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• 2001

A compact size microstrip antenna element using FR-4 substrate is proposed for use in repeater and base stations. Two stacked patches are aperture-coupled by two split feedlines. Rectangular stubs on the split feedlines are laid under the aperture and have the effect of considerably lowing the magnitude of $S_{11}$ [dB] and broadening impedance bandwidth. The designed structure has been fabricated and measured. Based on 20 dB, the return loss bandwidth is about 16.8% (1.86 GHz~2.20 GHz), which covers the frequency range assigned for IMT-2000 with a large margin. The overall dimension of the proposed antenna structure is 37 mm$\times$41 mm$\times$19mm (very compact). The antenna gain is more than 7.5 dBi over the required frequency range.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제24권1호
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• pp.124-129
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• 2010

When a phenolic resin is carbonized by the leakage current flowing along its surface, the carbonization pattern is one of the most important factors to determine its carbonization characteristics. However, the typical carbonization pattern of a phenolic resin is too complicated to be analyzed by conventional Euclidean geometry. In most cases, such a complicated shape shows a fractal structure. It is possible, therefore, to examine the characteristics of the carbonization pattern regarding a given phenolic resin. In order to quantitatively investigate the carbonization pattern of the phenolic resin carbonized by a leakage current, in this paper, the fractal dimension of the carbonization pattern has been calculated as a function of the magnitude of a leakage current and the distance between two electrodes. For reliability of calculation, the correlation function as well as the box counting method has been used to calculate the fractal dimension. According to the result of calculation, the fractal dimension increases as the current increases at the constant electrode gap distance. However, there is no significant relation between the fractal dimension and the electrode gap distance at a constant current.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.21-24
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• 2002

A sensor array (35mm'! in diaphragm dimension) of 12 sensing elements with different operating temperatures was optimized with respect to thermal operation. This sensor array with single heater on a glass diaphragm over back-etched silicon bulk realizes a novel concept of a sensor array: an way of sensor elements operated at different temperatures can yield more information than single measurement. The proposed micro sensor array could provide well-integrated way structure because it has only single heater at the center of the diaphragm and used the various sensing properties of two kinds of metal oxide layers with various operating temperatures.

• Health Policy and Management
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• 제12권4호
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• pp.34-55
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• 2002

In this study, the impact of organizational culture on the quality of social work services in hospitals were empirically analysed. A mailed questionnaire survey was conducted between February 19 and April 10, 2001. A sample of total 70 hospitals, including general hospitals with one social worker at least and single-department hospital with two social workers or more, were identified nationwide through the registry of Korean Association of Medical Social Workers and Korean Association of Hospitals. According to coping strategy and reacting pattern with the environmental changes, four types of organizational culture in each hospital, classified as group culture, developmental culture, hierarchial culture, and rational culture, were adopted for the independent variables. Three dimensional aspects of quality of social work service - structure, process, and outcome were selected as dependent variables in this study. Also the quality of social work service was distributed into provider-perceiving quality and consumer-perceiving quality The major findings were as following in summary; First, most social workers reported that the characteristic of culture in their hospitals are group culture the first, hierarchial culture the second, developmental culture the third, and rational culture finally in order of comparing the level of quality perceived between social worker's recognition. Second, service provider and consumer, The provider-perceiving quality showed less score than that of consumer, especially the lowest was the score of quality of outcome perceived by provider. Third, according to the types of organizational culture, there were significantly different levels of quality in total social work services, structure dimension and process dimension. The quality of outcome dimension did not show significant differences among the type of organizational culture. Finally, the most influential variables to the quality of social work service ice proved departmental form of social work unit, leader of social work unit, and developmental culture of hospital To assure quality services, accordingly, social work unit in hospital is required to be organized as a single unit, that means to be an independent department of which qualified social worker is supposed to control the unit. It is strongly recommended to develop leadership for the leaders of social work unit.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권10호
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• pp.3572-3590
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• 2014

Cellular automata (CA) based cryptosystem has been studied for almost three decades, yet most of previously reported researches focus on the symmetric key encryption schemes. Up to now, few CA based public key encryption scheme has been proposed. To fill the gap, in this paper, we propose a new public key encryption scheme based on layered cellular automata (LCA). Specifically, in the proposed scheme, based on the T-shaped neighborhood structure, we combine four one-dimensional reversible CAs (set as the private key) to form the transition rules of a two-dimension CA, where the two-dimension CA is set as the corresponding public key. Based on the hardness assumption of the Decisional Dependent CA problem in LCA, we formally prove the proposed scheme is indistinguishably secure against the chosen-plaintext attack (IND-CPA). In addition, we also use a numeric example to demonstrate its feasibility. Finally, analysis of key space and time efficiency are also carried out along with RSA-1024, and the simulation results demonstrate that our proposed scheme is more efficient.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.389-389
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• 2008

나노-스피어 리소그래피는 기존 리소그래피 방법에 비해 나노 크기의 패턴을 저비용에 공정이 간단하고, 대면적 패터닝이 가능하다는 장점이 있다. 본 논문에서는 나노-스피어 리소그래피 공정을 이용하여 실리콘 기판 위에 2차원 광자결정 구조를 제작하였다. 실리콘 기판 위에 직경이 500 nm 인 폴리스티렌 나노-스피어를 스핀 코팅 방법으로 단일막을 형성하였다. 스핀코팅 조건은 스핀속도와 시간을 조절하여 1단계는 400 rpm에서 10초, 2단계는 800 rpm에서 120초, 3 단계는 1400 rpm 에서 10초로 공정하였다. 그리고 산소 플라즈마를 이용한 반응성 이온 식각공정으로 폴리스티렌 나노-스피어의 크기를 조절할 수 있었으며, 이때 실리콘 기판 위에 형성된 다양한 크기의 폴리스티렌 나노-스피어 단일막은 금속막 증착시 마스크의 역할을 하게 된다. 금속막의 증착은 RF 마그네트론 스퍼터링 시스템을 이용하였으며, 공정 조건은 RF power를 100W, 공정 압력을 5 mTorr, Ar 유량을 10sccm으로 하였다. 스퍼터링 공정 후 폴리스티렌 나노-스피어를 제거함으로써 2 차원 광자결정 구조를 제작할 수 있었다. 실험 결과 단일막으로 형성된 폴리스티렌 나노-스피어의 크기를 조절함으로써 다양한 2차원 광자결정 구조 제작이 가능함을 확인할 수 있었다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제6권2호
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• pp.22-27
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• 2007

In this study, the two methods of stiffness measurement(Spring constant) of cantilever were proposed for quantitative measurement in Atomic Force Microscopy(AFM). As the 1st method for the measurement of stiffness, the probe method, which is used in the measurement of the semiconductor mechanical and electrical properties, was applied to the measurement of the cantilever. Experiments by the probe method were performed finding the resistance value of cantilever. As the results, the resistance was measured differently along with the dimension and the thickness of cantilever that determined the stiffness(spring constant) of the lever. As the 2nd method, the vibration characteristics(Dunkerley expression) is used to obtain the stiffness of the complex structure which is combined by AFM cantilever and the standard cantilever. We measured the resonant frequency from the complex structure using the micro stages and stereo microscope. As the results, we confirmed that the vibration characteristics(Dunkerley expression) is effected the micro complex structure of AFM cantilever.

• Journal of the Korean Society of Clothing and Textiles
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• 제28권9_10호
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• pp.1253-1264
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• 2004

The purpose of this study is to develop clothing shopping orientation[CSO] scale reflecting the conceptual structure of CSO. For this purpose, a questionnaire composed of comprehensive 85 CSO items was developed through 2-step preliminary tests. Data was collected from two samples. One sample(n=559) was for scale development and the other sample(n=235) was for cross validity test. Descriptive analysis, correlation analysis, exploratory factor analysis, regression analysis, ANOVA, and confirmatory factor analysis were used for data analysis. For each lower-dimension within the CSO conceptual structure model, 1-2 items were selected based on the quantitative and the qualitative standards. As a result, a CSO scale composed of 31 items was developed, and reliability, construct validity, cross validity, convergent validity, discriminant validity, and criterion validity of the scale were verified. This study has significance in offering the standardized scale to both the academic and the practical fields.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1138-1146
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• 2018

Performance comparisons of switched reluctance motor for cooling fan application are dealt in this paper. Conventional and novel segmental type motors with the same dimension are compared. The conventional 12/8 type is very popular and used widely. The structure of segmental rotor type motor is constructed from a series of discrete segments, and the stator is constructed from two types of stator poles: exciting and auxiliary poles. This type of motor has short flux path and no flux reversal in the stator. The auxiliary poles are not wound by the windings and only provide the flux return path. Compared with conventional SRM, the segmental structure increases electrical utilization of the machine and decreases core losses, which leads to higher efficiency. To verify the segmental structure, finite element method (FEM) is employed to get static and dynamic characteristics of both SRMs. Finally, the prototypes of conventional and segmental SRMs are tested for characteristics comparisons.

• Journal of Computing Science and Engineering
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• 제1권2호
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• pp.195-210
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• 2007

Dwarf is a highly compressed structure, which compresses the cube by eliminating the semantic redundancies while computing a data cube. Although it has high compression ratio, Dwarf is slower in querying and more difficult in updating due to its structure characteristics. We all know that the original intention of data cube is to speed up the query performance, so we propose two novel clustering methods for query optimization: the recursion clustering method which clusters the nodes in a recursive manner to speed up point queries and the hierarchical clustering method which clusters the nodes of the same dimension to speed up range queries. To facilitate the implementation, we design a partition strategy and a logical clustering mechanism. Experimental results show our methods can effectively improve the query performance on data cubes, and the recursion clustering method is suitable for both point queries and range queries.