• 충청수학회지
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• 제22권2호
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• pp.217-227
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• 2009

Assuming that a given nonlinear function f : $\mathbf{R}{\rightarrow}\mathbf{R}$ has a zero $\alpha$with integer multiplicity $m{\geq}1$ and is sufficiently smooth in a small neighborhood of $\alpha$, we define extended leap-frogging Newton's method. We investigate the order of convergence and the asymptotic error constant of the proposed method as a function of multiplicity m. Numerical experiments for various test functions show a satisfactory agreement with the theory presented in this paper and are throughly verified via Mathematica programming with its high-precision computability.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2006년도 공동학술대회 논문집
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• pp.3-6
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• 2006

There are three types of frequency-domain loop-loop EM induction method, depending on the loop separation and their location relative to the ground surface: horizontal-loop EM (HLEM), fixed small-loop EM, and helicopter-borne EM (HEM) methods. Multidimensional inversion provides tomographic images of the subsurface resistivity structure and thus enhances the interpretational accuracy of loop-loop EM data. HLEM method is shown to be effective for exploring groundwater resources in weathered and fractured crystalline basement terrains in semi-arid regions. Also, HEM method is useful for locating weak zones in landslide areas. The applicability of inversion to small-loop EM data depends solely on the S/N ratio. The quadrature response of small-loop EM data can only give the equivalent conductivity of a homogenous half-space model, and thus the in-phase component is essential in inverting EM data. However, the in-phase response is much lower and decreases more rapidly with decreasing frequency than the quadrature response. Further work is needed to obtain conductivity-depth images from small-loop EM data.

• 한국언어정보학회지:언어와정보
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• 제19권1호
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• pp.103-117
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• 2015

Not fully satisfied with the treatment of the so-called two nows in Korean by Lee & Choi (2009), this article seeks to furnish the issue with a firmer ground to base on in the relevant conversation. A close comparison between now and cikum appearing in the present perfect and present tense results in the two findings that (i) a crucial difference between the two adverbs is that Korean cikum lacks English now's ability to be identified with the reference time and (ii) further, seeming differences between them are not real but in fact due to tense and aspectual discrepancies between English and Korean. Thus, it claims, contra Lee (1976) and Park (2004), that cikum is a temporal locating adverb which invariably locates the event time of a given eventuality at the utterance time. In particular, it motivates that a past-tensed sentence with cikum should be understood as holding in the recent past mainly from pragmatic inferences rather than semantic entailments.

• 동력기계공학회지
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• 제12권5호
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• pp.14-19
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• 2008

In order to meet stringent future emission regulations, especially to reduce Particulate Matter (PM) and NOX, stoichiometric diesel combustion technology with a piezo group-hole nozzle injector is being researched for reduction harmful emissions. A new nozzle layout, namely a group-hole nozzle, which has one group of small orifices with a wide spray included angle was investigated to improve the efficiency of stoichiometric diesel combustion. From this point of view, the group-hole nozzle suggested by Dense Co. is an attractive candidate method applicable to stoichiometric diesel combustion. The group-hole nozzle concept is to reduce the injector nozzle hole diameters without sacrificing spray penetration by closely locating two holes. Experimental studies have proven that the spray from group-hole nozzles have similar spray penetration to that of a single hole with equivalent overall nozzle hole area, but the spray drop sizes (SMD) are reduced, aiding vaporization and mixing.

• 한국소음진동공학회논문집
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• 제14권2호
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• pp.95-104
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• 2004

Leaks in underground pipelines can cause social, environmental and economical problems. One of relevant countermeasures against leaks is to find and repair of leak points of the pipes. Leak noise is a good source to identify the location of leak points of the pipelines. Although there have been several methods to detect the leak location with leak noise, such as listening rods, hydrophones or ground microphones, they have not been so efficient tools. In this paper, accelermeters aroused to detect leak locations which could provide an easier and more efficient method. Filtering, signal processing and algorithm of raw input data from sensors for the detection of leak location are described. A 120m-long and a 70m-long experimental pipeline systems are installed and the results with the systems show that the algorithm with the accelerometers offers accurate pinpointing for leaks location detection. Theoretical analysis of sound wave propagation speed of water in underground pipes, which is critically important in leak locating, is also described.

• 비파괴검사학회지
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• 제25권3호
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• pp.201-208
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• 2005

In this paper, absolute and differential eddy current signals from various defects in the steam generator tube are numerically predicted and their signal slope characteristics are investigated. The signal changes due to frequency increase are also observed. After studying signal patterns from various defects and frequencies, the analysis of mixed defect signals affected by the presence of a ferromagnetic support plate is attempted. For the signal prediction, axisymmetric finite element modeling is used and this leads us to the slope angle analysis of the signal. Results show that differential signals are useful for locating the position of a defect under the support plate, while absolute signals are easy to presume and interpret even though the effect of support plate is mixed. Combined use of these two types of signals will help us accomplish a more reliable inspection.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.837-842
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• 2004

The positions of rotating sound sources have been localized by experiments with the Doppler effects removed. In order to do-Dopplerize the sound signals emitted from moving sources, two kinds of signal reconstruction methods were applied. One is the forward propagation method and the other is the backward propagation method. Forward propagation method analyze the source emission time based on the instantaneous distance between sensors and the assumed source position, then the signals are reconstructed with respect to the emission time. On the other hand, the backward method uses time delay to do-Dopplerize the acquired data for the received time of reference. In both techniques, the reconstructed signal data were processed using beamforming algorithm to produce power distributions at the frequency of interest. Experiments have been carried out for varying frequencies, rotating speeds and the object distances. Forward propagation method has shown better performance in locating source position than the backward propagation method.

• 한국소음진동공학회논문집
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• 제19권9호
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• pp.884-891
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• 2009

This study investigates some of swarm intelligence algorithms to tackle a traditional damage detection problem having stiffness degradation or damage in mechanical structures. Particle swarm(PSO) and ant colony optimization(ACO) methods have been exploited for localizing and estimating the location and extent damages in a structure. Both PSO and ACO are population-based, stochastic algorithms that have been developed from the underlying concept of swarm intelligence and search heuristic. A finite element (FE) model updating is implemented to minimize the difference in a set of natural frequencies between measured and baseline vibration data. Stiffness loss of certain elements is considered to simulate structural damages in the FE model. It is numerically shown that PSO and ACO algorithms successfully completed the optimization process of model updating in locating unknown damages in a truss structure.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.33-37
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• 2000

Milling fixture is one kind of machining device according to the industrial demands for multi manufacturing products on the growing at alarming rate. In the field of design and making for machine tool working, welding, assembling with fixture for mass production is a specific division. In order to prevent the production defects, occurring, the optimum design of product, fixture putting in the field is very significant manufacturing method. They require analysis of many kinds of important factors, theory and practice of machine tool operating process and its situations, fixture and its structure, machining condition for tool making tool materials, heat treatment of fixture components, know-how and so on. In this study we designed and constructed a milling fixture of mass production and performed tryout under the AUTO CAD, database, I-DEAS and WINDOW environment. Especially part 1 of this study is reveals with the analysis of part drawing, fixture planning, fixture design etc.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2004년도 추계학술대회 논문집
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• pp.361-366
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• 2004

This study has carried out in order to furnish the fundamental material to systemize the lecture room into multimedia in the future, by locating college lecture room as the subject of study, by compare and analyze on acoustic character in both before and after of each improvement. Thereby, now we are about to compare and analyze on physical character of room acoustics in both common lecture room before improvement and the modified multimedia-lecture room after its improvement. Observing the conclusion obtained through experiment, reverberation time in the modified 'lecture room after improvement' became shorter compare with the 'lecture room before improvement', definition and RASTI also improved to be suitable to lecture, and considered that it is able to elevate the intimacy with studying and teaching efficiency, as well.