• 한국산업융합학회 논문집
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• 제26권3호
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• pp.395-400
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• 2023

Recently, the number of hornet is rapidly increasing because of change in the ecological climate. It gives a sense of threat to the people and damages the beekeeping industry as a predator of honey bees. Firefighters are working to remove hornet and vespiary, but it has been reported that it is difficult to remove at high altitudes. In this study, an ultra-light flying device was developed to remove vespiary. It has been developed in four types: Drug spray type, Clamp type, Cutter type, and Scraper type, which can be used as field-customized equipment. Therefore, the developed equipment is expected to contribute to the safe field activities of firefighters.

• 대한지구과학교육학회지
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• 제4권3호
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• pp.297-304
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• 2011

The objective of the research which it sees to investigate and teachers elementary school preparation should have had what kind of line concept from astronomical field, to interpret. The research questions of this study were as follows. It tried to observe the result which investigates the line concept of teachers preparation in about conceptual gain and loss degree of the astronomical field which it comes to reveal from the research which it sees. The students where are not the scientific department of pedagogy and the scientific department of pedagogy were visible a relatively high gain and loss degree from the earth shape and phase change of month during one night. Also the part which it thinks rhinologically was many. When it presents the type, with afterwords it is same. First, The endurance rotates in about location change of month during various day, it revolves with the direction where also the month is the same type which does not know a fact, The students do not recognize well in about the shape of month changing everyday the type. The students does not understand the location which the month when it follows at time is accurate well the type was many. Second, when it tries to compare a scientific department of pedagogy 3 grade and a rhinologic department of pedagogy 3 grade, the gain and loss degree of most scientific department of pedagogy 3 grade is appearing highly.

• 소음진동
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• 제7권1호
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• pp.43-53
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• 1997

This paper investigated the practical use for measuring the structural intensity (power flow per width of cross section) in a uniform semi-infinite beam in flexural vibration. The structural intensity is obtained as a vector at a measurement point, One-dimensional structural intensity can be obtained from 4-point cross spectral measurement, or 2-point measurement on the assumption of far field. The measurement errors due to finite difference approximation and phase mismatch of accelerometers are examined. For precise measurements, it would be better to make the value of k$\delta$(wave number x space between accelerometers) between 0.5 and 1.0. Formulation of the relation between bending waves in structures and structural intensity makes it possible to separate the wave components by which one can get a state of the vibration field. Experimental results are obtained from 2- and 4-point measurement performed at 200mm (near field) and 400mm (far field) apart from excitation point in random excitation. the results are compared with the theoretical values and measured values of input power spectrum in order to verify the accuracy of structural intensity method, 2-point method is suggested as the practical structural intensity method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.502-505
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• 2006

Acoustic holography allows us to predict spatial pressure distribution on any surface of interest from measured hologram. It is noteworthy that the data size is so huge that it takes long time to calculate pressure field. Moreover the reconstructed pressure field is frequently too complicated to get what we want to know. One possible candidate is complex envelope. Complex envelope in time domain is well known and widely used in various engineering field. We have attempted to extend this method to space domain, so that we can have rather simple spatial pressure picture that provides information we need, for example, where sound sources are. First we start with the simplest case. We examine the complex envelope of a plane wave on both space and wave number domain. Then we extend to monopole case. Holographic reconstructed sound field on the monopole is processed according to what we propose. We demonstrate how this method provides better picture for analyzing the sound field.

• 대한기계학회논문집A
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• 제21권11호
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• pp.1844-1851
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• 1997

Displacement fields and interface stresses are obtained by modifying the potential energy functional with a penalty function which enforces the continuity of stresses at the interface of two-materials. Based on the displacement field and the interface stresses, a new methodology to generate a continuous stress field over the entire domain including the interface of the dissimilar materials has been proposed by combining the L$^{2}$ projection method of stress-smoothing and the Loubignac's iterative method of improving the displacement field. Stress analysis was carried out on two examples which are made of highly dissimilar materials. As a result of the analysis, it is found that the proposed method provides improved continuity of the stress field over the entire domain as well as predicting accurate nodal stresses at the interface. In contrast, the conventional displacement-based finite element method provides significant stress discontinuties at the interfaces. In addition, it was found that the total strain energy evaluated from the improved continuous stress field converge to the exact value as increasing the number of iterations in the proposed method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.172-176
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• 1997

It is likely that the corona discharge appears due to the motion and the multiplication of electron and ion under the nonuniform electric field. Because the motion and the multiplication of electron and ion are the function of electric field, for the simulation of the corona discharge, we have to calculate the electric field, before the calculation of the motion and the multiplication of electron and ion. In this paper, the electric field is calculated on the assumption that the gap between a hyperboloidal needle and a plane is 1-dimension, and the motion and the multiplication of electron and ion are determined by Flux-Corrected Transport method. For this purpose, we solve the electron and ion continuity equation together with Poisson equation. We calculated the current density and the electron and ion density distributions between electrodes as well as electric field distortion due to the space charge assuming that the discharge channel radius is 100${\mu}{\textrm}{m}$. In this simulation, it is found that the current density has one peak as observed by experiment, and electric field distortion is important to the formation and the stability of the corona discharge.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권6호
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• pp.469-474
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• 1999

Methods and systems to remove static electricity are requested in the field of industry because the static electricity causes a flammable gas explosion or fire and a reduction of production rate in manufacturing semiconductor devices and so on. This paper is a basic study about a new structure of electrode system to control the quantities of generated ions and to solve the problem of dust attachment to needle electrode. In addition, a new type field controlled electrostatic charge neutralizer was proposed, and it could control the electric field in the end of the needle electrode by controlling the voltage of the third electrode around the tip of the needle electrode. As aresult, it was possible to control the quantities of generated ion by controlling the electric field in the needle electrode with the third electrode, which shows the possibilities to solve the nonequilibrium of generated ions in ac power source and the problem of the dust in the needle electrode.

• 대한가정학회지
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• 제44권12호
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• pp.19-30
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• 2006

The present study investigated the effects of children's cognitive styles on their interpersonal problem solving performances. It examined closely whether children's interpersonal problem solving performances differed depending on their individual cognitive styles such as field independence-field dependence and reflection-impulse cognitive styles. It also examined whether children's interpersonal problem solving performances differed depending on the subjects children interacted with. The subjects were 80 5-and 6-year-old children from three child care centers. Collected data were analyzed with SPSS Win 10.0 and processed statistically using average, standard deviation, and repeated measures design. Children's interpersonal problem solving performances showed differed according to the subjects they interacted with. Children showed better interpersonal problem solving performances with their peers than with adults like teachers or parents. There was a significant positive correlation between children's field independence-field dependence cognitive styles and interpersonal problem solving performances. That is, the more independent children were, the higher their interpersonal problem solving performances were. In addition, there was a partially negative correlation between children's reflection-impulse cognitive styles and interpersonal problem solving performances. The more impulsive children were, the lower the problem solving performances were.

• 천문학회보
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• 제42권2호
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• pp.43.1-43.1
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• 2017

A three-dimensional (3D) $Ly{\alpha}$ radiative transfer code is developed to study the Wouthuysen-Field effect, which couples the 21 cm spin temperature of neutral hydrogen and the $Ly{\alpha}$ radiation field, and the escape fraction of $Ly{\alpha}$ from galaxies. The Monte Carlo code is capable of treating arbitrary 3D distributions of $Ly{\alpha}$ source, neutral hydrogen and dust densities, gas temperature, and velocity field. It is demonstrated that the resonance-line profile at the center approaches to the Boltzmann distribution with the gas temperature. A plane-parallel ISM model, which is appropriate for the neutral ISM of our Galaxy, is used to calculate the $Ly{\alpha}$ radiation field strength as a function of height above the galactic plane. We also use a two-phase, clumpy medium model which is composed of the cold and warm neutral media (WNM). It is found that the $Ly{\alpha}$ radiation field is strong enough to thermalize the 21 cm spin temperature in the WNM to the gas kinetic temperature. The escape fraction of $Ly{\alpha}$ is found to be a few percent, which is consistent with the $Ly{\alpha}$ observations of our Galaxy and external galaxies.

• 농촌계획
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• 제23권1호
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• pp.21-29
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• 2017

The purpose of this study is to analyze the accuracy of cultivated crop database in agricultural farm business using UAV(Unmanned Aerial Vehicle) and field survey over Daesso-myeon, Umsung-gun, Chungbuk. When comparing with agricultural farm business and cadastral maps, Daeso-myeon crop field shows 29.8%(2,030 parcels out of 6,822 parcels) is either mismatched or missing. It covers almost 19.3%($3.4km^2$ of $17.6km^2$) of total farmland. In order to solve these problems, it is necessary to prepare a multifaceted plan including cadastral map. Comparative analysis of the cultivated crop registered in the agricultural farm business and the field survey agreed only in 3,622 parcels in total 6,822 parcels whereas 3200 parcels disagree. Among these disagreed parcels 2,030(29.8%) have been confirmed as unregistered farm business entity. Accuracy of cultivated crop registered in agricultural farm business agreed in 75.6% cases. Especially the paddy field registration is more accurate that other crops. These discrepancies can lead to false payment in agricultural farm business. For exploration and analysis of regional resources, UAV images can be used together with farm business management database and cadastral map to get a clearer grasp over on-site resources and conditions.