• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.714-720
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• 2008

This research presents a laboratory study about an subjective response of impulsive sound caused by leisure shooting. The sources are sampled from outdoor noise and their levels range from 40 to 75 dB at the interval of 5dB. The noise unit is based on A-weighted sound exposure level (ASEL; $L_{AE}$). To make equal ASEL of outdoor noise, finite impulse response (FIR) filter is applied to the originally sampled source to include the effect of distance attenuation. The evaluation method of the jury test adopted a Semantic Difference(SD) Method. In the result of the jury test for impulsive noise, the mean response rating expressed a linear relation and %HA(percent highly annoyed) displayed a exponential growth relation.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2005년도 추계학술대회 논문집
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• pp.269-272
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• 2005

The purpose of this study is to analyze the relation between the dwelling location and the satisfaction level, and suggest a proposal to increase the quality of the livability space. A first of this study began from public surveys conducted to gather the information of satisfaction level from 4 multi-family housing sites in Gwang-ju. The plan was to the characteristics of the LS(livability space). The poll and the observation investigation was run concurrently. The cross analysis and the frequency analysis were used to analyze the data from the questionnaires. The validity of fixed quantitative index was got through the correlation analysis between the result of former analysis and index of livability space. The result said that the dwelling location have relations with the satisfaction level. In the conclusion, this will be a suggestion of the methods to enhance equal-quality of the livability space.

• Coupled systems mechanics
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• 제7권4호
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• pp.407-420
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• 2018

In solid-liquid two phase flow, the knowledge of how descending solid particles affected by the presence of downstream wall is important. This work studies at what interstitial distance the velocity of a vertically descending sphere is affected by a downstream wall as a consequence of wall-modified hydrodynamic forces through a validated dynamic model. This interstitial distance-the hydrodynamic coupling distance ${\delta}_c-is$ found to decay monotonically with the approach Stokes number St which compares the particle inertia to viscous drag characterized by the quasi-steady Stokes' drag. The scaling relation ${\delta}_c-St-1$ decays monotonically as literature below the value of St equal to 10. However, the faster diminishing rate is found above the threshold value from St=10-40. Furthermore, an empirical relation of ${\delta}_c-St$ shows dependence on the drop height which clearly indicates the non-negligible effect of unsteady hydrodynamic force components, namely the added mass force and the history force. Finally, we attempt a fitting relation which embedded the particle acceleration effect in the dependence of fitting constants on the diameter-scaled drop height.

• Journal of Magnetics
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• 제22권2호
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• pp.188-195
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• 2017

The ferromagnetic resonance and other magnetic properties dependence on $Ni^{2+}/Fe^{3+}$ ratio and crystallite size were investigated for nano nickel ferrite ($NiFe_2O_4$). The crystallite size was controlled by controlling the nickel content in the starting material solution. The XRD and TEM were utilized to measure the crystallite size through Scherrer formula and particle size respectively. The most frequent particle sizes were lower than crystallite size, which ranged from 16.5 to 44.65 nm. The general behavior of M-H loop shapes and parameters showed superparamagnetic one. The saturation magnetization had a maximum value at $Ni^{2+}/Fe^{3+}$ molar ratio equal to 0.186. The FMR signals showed, generally, broad linewidths, where the maximum width and minimum resonance field were for the sample of the lowest crystalline size. Furthermore, FMR resonance field shows linear dependence on crystalline size. The fitting relation was estimated to express this linear dependency on the base of behavior coincidence between particle size and the inverse of saturation magnetization. The given interpretations to understand the intercept and the slope meanings of the fitted relation were based on Larmor equation, and inhomogeneous in the anisotropy constant.

• 한국학교수학회논문집
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• 제16권4호
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• pp.883-898
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• 2013

본 연구의 목적은 고등학교 학생들이 동일한 수학적 상황을 다른 형태로 제시할 때 수학 문제해결 능력을 분석 연구하는데 있다. 본 연구의 결과로부터 얻어진 결론은 다음과 같다. 첫째, 동일한 수학적 상황을 함수로 제시한 문항이 방정식과 부등식으로 제시한 문항보다 정답률이 높았으며, 일차방정식 일차부등식과 일차함수와의 관계를 묻는 문항보다 이차방정식 이차부등식과 이차함수와의 관계를 묻는 문항에서 정답률이 떨어졌다. 둘째, 방정식과 부등식 문항을 기계적인 계산에 의해서 푸는 문항을 주로 접해온 학생들은 면담 결과 그래프에서 나타나는 교점이 연립방정식의 해라고 알고 있는 학생은 많았지만 그것을 그래프를 그리거나 해를 구하는 데 사용하지 못하는 것으로 보아 방정식과 함수와의 관계에서 동일한 수학적 상황을 인식하지 못한 것을 알 수 있었다. 셋째, 면담을 통하여 학생들이 방정식 부등식과 함수에 대한 관계를 어떻게 생각하고 있는지 알아본 결과, 관계에 대한 정확한 이해 능력이 없음에도 정답을 구하는 경우가 있었다.

• Journal of applied mathematics & informatics
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• 제34권1_2호
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• pp.75-84
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• 2016

The objective of this work is to perform a geometric analysis of the net present value (NPV) and Internal Rate of Return (IRR), defining analytics and in verifying the relationship between geometric properties of such functions. For this simulation, was used the values of the cash flows for each period identical and equal to US$ 200.00 cash, the initial investment US$ 1,000.00 and investments of each identical and equal to US$ 50.00 period. In addition, the discount rate and time were considered a maximum of 2 years (24 months) at a rate between 0 and 100%. The geometric analysis of the characteristics obtained from the expressions of the Net Present Value and Internal Rate of Return possible to observe that besides the analytical dependence between these quantities , the geometric relationships are relevant when studied in relation to the zero NPV and expressed a great contribution the sense of a broad vision for the administrator in the analysis of analytical variables that in uences the balance sheet of the company.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.427-430
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• 2008

The influence of subsequent annealing treatment on the dynamic deformation and the fracture behavior of submicrocrystalline Al-4.4%Mg alloy is investigated in this study. After inducing an effective strain of 8 via equal-channel angular pressing at $200^{\circ}C$, most of the grains are considerably reduced to nearly equiaxed grains of $0.3{\mu}m$ in size. With an increment of various subsequent heat treatments for 1 hour, resultant microstructures are found to be fairly stable at temperatures up to $200^{\circ}C$, suggesting that static recovery will be dominantly operative, whereas grain growth is pronounced above $250^{\circ}C$. The results of tensile tests show that yield and ultimate tensile strength decrease, but elongation-to-failure and strain hardening rate increase with an increase in annealing temperatures. The dynamic deformation and the fracture behavior retrieved with a series of torsional tests are explored with respect to annealed microstructures. Such mechanical response is analyzed in relation to resultant microstructure and fracture mode.

• 대한금속재료학회지
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• 제46권9호
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• pp.563-571
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• 2008

The influence of annealing treatment on dynamic deformation behavior of ultra-fine grained aluminum alloys was investigated in this study. After equal-channel angular pressing at $200^{\circ}C$, most of the grains were considerably reduced to nearly equiaxed grains of $0.3{\mu}m$ in size. With an increment of various annealing treatments for 1 hour, resultant microstructures were found to be fairly stable at temperatures up to $200^{\circ}C$, suggesting that static recovery would be dominantly operative, whereas grain growth was pronounced above $250^{\circ}C$. The tensile test results showed that yield and ultimate tensile strengths decreased, but elongation-to-failure and strain hardening rate increased with increasing annealing temperature. The dynamic deformation behavior retrieved with a series of torsional tests was explored with respect to annealed microstructures. Such mechanical response was analyzed in relation to resultant microstructure and fracture mode.

• 한국실내디자인학회논문집
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• 제21권1호
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• pp.40-50
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• 2012

This study aims at suggesting the applicability of color combination based upon the characteristics of environmental color perception and the nuance concept of Natural Color System(NCS). The results are summarized below: First, NCS is a scientific coloring system in consideration of the relevance between people, light and environment, to be based on a phenomenological point of view. NCS can be called a psychometric model reflecting our natural color sense. Second, the color triangle established by NCS is one of the methods of expression based on the human visual mechanism, which is classified by two attributes of hue and nuance, not by the three color attributes of hue, lightness and saturation. The nuance concept of NCS implies the impression, atmosphere and tone that are perceived in colors, which are related to lightness and saturation. Accordingly, this paper suggests that the coloring arrangement emphasizing nuance and tone is more useful than hue in color planning. Third, aesthetic impression in environmental color perception is inclusive of instantly perceptive nuance, which is connected with affordance. The affordance is revealed by the different relation of similarity. In this regard, a strong relationship is noticed between color combination and the sense of pleasantness. The hypothesis regarding the complementation and similarity of contrasting nature is judged to provide observers with aesthetic order. Finally, this paper also suggests four harmonizing methods in the NCS color triangle based upon equal blackness, equal whiteness, equal chromaticness and same nuance. At the same time, opposition and a different concept of hue, lightness and lightness are combined complementarily with the nuance value to suggest patterns of color combination.

• 대한수학교육학회지:수학교육학연구
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• 제14권4호
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• pp.367-385
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• 2004

이 연구에서는 남북한 초등학교 교과서에서 분수를 도입하는 과정을 분할분수와 동치분수로 나누어 비교하여 차이점을 파악하고 그에 관해 반성적으로 논의를 전개하였다. 논의 결과, 남한 교과서는 사과와 같은 구체물을 등분할하는 활동의 소재로 사용하고 있으나, 북한 교과서에는 그와 같은 구체물을 실제로 등분할하는 활동은 제시되어 있지 않았다. 남한의 교과서는 연속량의 등분할과 이산량의 등분할을 시간 간격을 두고 다루는데 비해, 북한 교과서는 분수 도입 시점에서 같이 다룬다는 것도 확인하였다. 측정 단위가 붙은 양분수의 사용 측면에서도 남북한 교과서는 차이를 드러냈다. 또한 외연적 방법에 따라 분수를 도입한다는 점에서는 공통적이지만, 남한과 북한은 활동과 의미에 어느 정도 초점을 두는가에 있어서 차이를 보였다. 동치분수를 도입하는 방식을 비교한 결과, 세 가지 차이점을 확인하였다. 가장 큰 차이는 동치분수를 구하는 직접적인 방법을 제공하는가, 동치분수의 특성과 동치 분수를 구하는 방법에 대한 탐구를 자극하는가하는 측면에서 확인할 수 있었다.