• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.271-273
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• 2007

This paper presents the experimental results of underwater discharges in 25 mm point-plane gap caused by impulse voltage. Discharge phenomena were observed by digital cameras and recorded by oscilloscope. As a result, discharge patterns in positive and negative polarity have different shapes according to applied voltage amplitudes. The positive discharge is like root but the negative discharge is similar to bush. As the voltage is increased, the discharge routs are thick and have more branches. Also the time to breakdown is inversely proportional to voltage.

• Journal of the Korean Institute of Rural Architecture
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• v.4 no.2
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• pp.27-37
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• 2002

From the point of tectonic manner which is 'how to build a house' this study considers the characteristics of Kan in Hyangdan(香壇) at Yang-Dong Village. It was analysed with primary elements such as Kan, condition of a site, module, structural system, roofing system and their relationships in spatial and formal composition. Through the analysis, findings were achieved that characteristics of Kan to form a rectangle of 1 to root 2 proportion plan, enable irregularity in usage and regularity in compositional aspect and structural system to achieve intended roof design. In addition, Kan as a module is found to have a relative value that also regulates the whole in structural and aesthetical aspects.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.448-450
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• 2005

A ubiquitous network allows all users to access and exchange information of any kind freely at any time, from anywhere, and from any appliance through the use of broadband and mobile access. Bluetooth commincation can provide the missing wireless extension to the heterogeneous network, allowing a more ubiquitous access. In this point of view, the BT specifications define ways for which each BT device can set up multiple connections with neighboring devices to communicate in a multi-hop fashion. this paper provides insights on the Bluetooth technology and on some limitations of the scatternet formations. so that, we describe a new multi-hop routing protocol for the establishment of scatternets. this protocol defines rules for forming a multi-hop topology in two phases. the first phase, topology discovery, concerns the discovery of the node's depth from a root node initiating inquiry process. the second phase forms scatternet topology based on the result of topology discovery.

• Korean Journal of Computational Design and Engineering
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• v.3 no.2
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• pp.103-112
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• 1998

In this paper insertion of numerous control points to be performed by using the Chebyshev polynomial root at the selection of knot vector. This method introduces a simple method of knot refinement and it is applied in a developed program. The Chebyshev roots exist densely in broth ends of the range and are proposed more effective knot refinement to modify a surface. Therefore, generated control points are relatively uniform in specified knot interval. In the surface generation, a local insertion of numerous control points are easily inserted by using the characteristic of Chebyshev polynomial roots at knot refinement. It is possible to create a complex surface with a single surface. The number of control point can be reduced by using the local insertion of control points in a required shape

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.208-217
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• 2003

In order to construct the extrusion die surface of T -shaped sections, an automatic surface construction method based on NURBS surface and area mapping method is proposed in the present work. In the present study, a center point for area mapping is determined by introducing the mapping concept based on constant area proportionality between original billet and final product. The characteristic points of inlet profile are determined using the traditional area mapping method and the root finding numerical method. The inlet and outlet profiles are precisely described with NURBS curves using the characteristic points of entry and exit sections. For the construction of NURBS surface, an interpolation method for the pre-determined two section curves has been developed to be used in the generation of interior control points and weights. To show the validity of the proposed method, automatic die surface generation is carried out for the T-shaped section and T-shaped section with rounded corners.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.66-69
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• 2008

In this paper, The author present a load current feed-forward compensator by method that improve voltage controller of Step-down Chopper to get stable output voltage to sudden change of load current. To confirm the characteristicsof a presented load current feed -forward compensator compared each transfer function of whole system that load current feed-forward compensator is added with transfer function of whole system that existent voltage controller is included using Mason gains formula in Root locus and Bode diagram. As a result the pole of system is improved, extreme point of the wave and system improves, and size of peak value and phase margin of break frequency in resonance frequency confirmed that is good. Therefore, presented control technique could confirm that reduce influence by perturbation and improves stationary state and dynamic characteristics in output of Step-down Chopper.

• Water for future
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• v.5 no.2
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• pp.30-43
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• 1972

The paper describes on the hydrologic analysis of point rainfall data of the three major areas, such as in Seoul, Pusan and Taegu. Scheme of the paper is analyzed five research cases. Contents of the analysis are carried out five kinds of transformed variables for determination of rainfall distribution types and two kinds of reliability tests on unusual(extraordinary) values each rainfall durations:short durations, long durations, long durations, monthly and yearly. Rainfall depth probability had been computed methods of hydrologic amounts analysis namely logarithmic transformations or Gumbel-Chow method and so on, but in this paper it is calculated log xi, n-square root transformations by using normal distribution function and normalization of rainfall distributions is examined graphical tests and $X^2-test$(chi-square test). Furthermore, rainfall depth probability is calculated taking into account the safty factors of project life of hydraulic structures. We think it is advanced contents that considering priceless experiences, the life of structures, conditions and more problems of planning engineers and designers, proposed rainfall amounts(proposed values) are presented charts or figures.

• Journal of Plant Biotechnology
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• v.36 no.4
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• pp.344-351
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• 2009

Current status of soybean transformation method in Korera was reviewed with recent publications. Most frequently used method for genetic transformation was Agrobacterium-mediated transformation on cotyledonary node which is most popular method used in foreign country. In addition to this, various methods such as sonicationmediated transformation, in planta transformation, and transformation on meristem tissue of germinating seed, have been tried in Korea, even though their efficiencies on repeatability and stability were relatively low. Based on the promising results developed recently by reviewer, several important considerations for successful soybean transformations were suggested. They are 1) proper genotype screening, 2) targeting transformation on exact point, 3) multiple shoot formation, 4) efficient selection pressure, 5) successful shoot elongation, 6) efficient root formation. These are the basic requirements for stable and highly efficient soybean transformation of Korean soybean.

• Journal of Chest Surgery
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• v.12 no.3
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• pp.183-190
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• 1979

A 23-year-old male patient complained dyspnea on exertion and orthopnea since December 1977. On examination, he was tall and slender. There was grade IV/VI to-and-fro murmur on the left sternal border especially on Erb`s point. The liver was descended 2 fingers breadth below right costal margin. There were no signs of Marfan`s syndrome. Echocardiography demonstrated partial closure of aortic valve and dilated aortic root with enlargement of ascending aorta. Left heart cardiac catheterization revealed moderately elevated pulmonary wedge pressure and right ventricular pressure. The left ventricular end diastolic pressure was markedly elevated to 26 mmHg. On aortography, the aortic regurgitation was severe and it was belonged to angiographically Grade IV. The aortic valve was replaced with Carpentier-Edwards valve without excision and replacement of ascending aorta, under the impression of rheumatic valvular heart disease. After closure of aortotomy, blood pressure was transiently elevated and bleeding from the site of inserting air vent needle of ascending aorta was developed. The bleeding was not controlled by any means. On postmortem microscopic study, the histologic changes were strikingly limited to the ascending aorta from the region of the aortic valve ring.

• Tunnel and Underground Space
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• v.5 no.2
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• pp.89-94
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• 1995

Regression analysis and a comparative study were carried out for 52 blast vibration data which were monitored by changing the monitoring distance and charge per delay. The results are as follows: 1) The square and cube root scalings and general equation which have a confidence level at the point of 90% and 99% are V90=33300(SD)-2.026 , V90=23600(SD)-1.993, V90=26300W0.755 R-2.007 and V99=48400(SD)-2.026, V99=34000(SD)-1.993 , V99=38100W0.755R-2.007, respectively. 2) There is need to decide the allowable max. charge weight per delay considering the cross points comparatively of the nomogram constructed using several predictived equations. 3) It is necessary to derive the predictive equation on the basis of blast vibration level monitored in field and to decide safe vibration level and the confidence level.