• 한국환경보건학회지
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• 제27권1호
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• pp.100-105
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• 2001

Microstructural examinations were performed on the anaerobic biofilm from reactor filled with PE support media. Optical microscope, SEM and fluorescent microscope were used for qualitative and morphological studies on the attached microorganism under anaerobic condition. Microorganisms were attached in crevices where protection from shear forces of surfaces where easy to contact with support media surface. A hypothesis for biofilm accumulation occurs on a surface such as polymer support media is presented schematically : 1st step ; cell-support media attachment, 2nd step ; cell-support media attachment and cell-cell attachment, 3rd step ; attached biofilm from neighboring crevices joins together and growing, 4th step ; mature and irregualar biofilm was formed. In SEM photographs, shape and structures of biofilm were observed, but microorganism species and methanogens were not identified. A large number of methanogenic bacteria were identified on the surface of PE substratum by fluorescence under 480nm of radiation and it was estimated that methanogenic bacteria was related to initial attachment of bacteria under anaerobic condition.

• 대한기계학회논문집A
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• 제25권12호
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• pp.1974-1980
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• 2001

The control algorithm of a new type self-bearing step motor is presented. The motor actuator is used for both motor and bearing functionality without any redundant coil windings or redundant electromagnets. The self$.$bearing step motor layout and its control method are described. A linearized farce-current-displacement relationship is derived. As the result of the unbalance response approach, the constant torque production is possible fur the supply current regulation algorithm. And even if the bearing functionality is added in the motor functionality, no additional current for bearing functionality is possible, and this leads to minimize the net power loss. Also, the unbalance response shows the independent bearing force and motor torque.

• 한국자동차공학회논문집
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• 제22권6호
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• pp.39-48
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• 2014

Variable valve actuation system is one of the widely used techniques to improve the fuel efficiency and power of automotive engines. 2-step variable valve actuation systems are also paid attention for the application to direct acting type valve train systems. Besides its advantages in size, weight, relatively simple structure, ets, however, 2-step variable valve actuation system has inherent disadvantages in dynamic instability of switching system to alter discontinuous lift modes. In this study, both experimental and analytical studies are performed to understand the dynamic behavior of a switching mechanism of a 2-step variable valve actuation system, and present a design method to improve its dynamic instability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.51-54
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• 1991

The effect of inductance for optimal design of Hybrid permanent magnet step motor is presented on this paper. A pull-out torque of Hybrid permanent magnet step motor is measured and calculated by varying stator coil inductances, and power consumption of the step motor also is calculated and compared to the measured value. The relation of developed torque to parer consumption by the changing of magnetomotive force magnitude in a rotor permanent magnet is studied, which is the essence of the step motor design.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.13-16
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• 2005

It would be desirable to have methods for specific problems, which have low communication costs compared to the computation costs, and in specific applications, algorithms need to be developed and mapped onto parallel computer architectures. Main memory access for shared memory system or global communication in message passing system deteriorate the computation speed. In this paper, it is found that the m-step generalization of the block Lanczos method enhances parallel properties by forming m simultaneous search direction vector blocks. QR factorization, which lowers the speed on parallel computers, is not necessary in the m-step block Lanczos method. The m-step method has the minimized synchronization points, which resulted in the minimized global communications compared to the standard methods.

• 전기학회논문지
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• 제56권3호
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• pp.465-471
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• 2007

The one step type pole and two step type pole are used in KEPCO's distribution system. The neutral current increases in three-phase four-wire distribution system due to unbalanced load. Usually, power line and communication line are installed at contiguity by effect of topography in Korea. To this end, the damages such as electrostatic induction, electromagnetic induction and harmonic induction generated by induced voltage and current are occured in power line and communication line. This paper calculates the neutral current in KEPCO's distribution system using EMTP by composing various simulated conditions. Also, these results are verified by vector analysis.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.233-238
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• 2011

In the present work, a new approach is proposed for via interconnects of semiconductor devices, where multi-wall carbon nanotubes (MWCNTs) are used instead of conventional metals. In order to implement a selective growth of carbon nanotubes (CNTs) for via interconnect, the buried catalyst method is selected which is the most compatible with semiconductor processes. The cobalt catalyst for CNT growth is pre-deposited before via hole patterning, and to achieve the via etch stop on the thin catalyst layer (ca. 3nm), a novel 2-step etch scheme is designed; the first step is a conventional oxide etch while the second step chemically etches the silicon nitride layer to lower the damage of the catalyst layer. The results show that the 2-step etch scheme is a feasible candidate for the realization of CNT interconnects in conventional semiconductor devices.

• 대한산업공학회지
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• 제23권3호
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• pp.597-608
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• 1997

Life cycle product data is very important yet difficult to handle for manufacturing companies. Shoring and exchanging product data over world-wide-web is a part of key technology to implement PDM or CALS. STEP is widely accepted as a standard to represent the life-cycle product model data. Described in this paper is a web browser plug-in that can graphically display and explore product data represented by STEP over internet. By the use of the plug-in (named "npSTEP"), a product model data stored in STEP format on a web server can be displayed on a commonly used web client (browser), such as Netscape navigator, without any format conversion process. Furthermore one can explore the components or attributes of the product model data in hierarchical manner.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2006년도 추계 학술대회
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• pp.404-410
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• 2006

6시그마 프로세스는 정의(Define), 측정(Measure), 분석(Analyze), 개선(Improve), 관리(Control) 라는 다섯 Step을 통하여 문제를 해결하고 성과를 달성한다. 이 다섯 단계 중에서 측정 단계는 6시그마로는 길에서 매우 중요한 전이 단계로서 문제점을 정교하게 다듬고 근원적 원인 규명을 시작하는 데 도움을 준다. 즉 개선 하고자 하는 영역에 대한 사실적 근거를 제공 받기 위해 프로세스를 숫자로 전환 할 때 무엇을 측정하고 어떻게 측정 할 것인가를 결정한다. 측정단계는 주로 3 Step으로 이루어진다. Step 1 은 CTQ 특성치의 선정, Step 2는 성과기준의 정의, Step 3은 측정시스템의 분석이다. F사의 6시그마 발표자료 중 측정 부분만을 집중 분석하여 문제점 및 그 개선 방향을 제시하려한다.

• Journal of the Korean Statistical Society
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• 제34권3호
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• pp.219-233
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• 2005

The 3-way balanced multi-level rotation design has been discussed (Park Kim and Kim, 2003), where the 3-way balancing is done on interview time, in monthly sample and rotation group and recall time. A greater advantage of 3-way balanced design is accomplished by an estimator. To obtain the advantage, we generalized previous generalized composite estimator (GCE). We call this as l-step GCE. The variance of the l-step GCE's of various characteristics of interest are presented. Also, we provide the coefficients which minimize the variance of the l-step GCE. Minimizing a weighted sum of variances of all concerned estimators of interest, we drive one set of the compromise coefficient of l-step GCE's to preserve additivity of estimates.