• Journal of Forest and Environmental Science
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• 제20권1호
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• pp.93-109
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• 2004

본 연구는 산악지형에 적합한 임도노선을 개설하기 위한 기초 자료를 제공하기 위하여, 강원도 지역에 있어서 물리적으로 안정된 임도를 대상으로 지역별, 산지경사별, 토성별, 개설위치별에 따른 사면경사, 사면길이, 노폭 등의 임도구조요인의 변화에 대하여 분석하였다. 지역별 임도구조는 성토길이만 유의적인 차이가 없는 것으로 나타났으며, 그 이외의 지역은 각각 차이를 보이고 있었다. 산지경사별 임도구조는 노폭, 종단물매, 성토길이, 절토길이는 유의적인 차이가 보이지 않았으며, 성토경사는 $30^{\circ}$이하 $30{\sim}35^{\circ}$와 $40^{\circ}$이상에서, 절토경사는 모든 지역에서 차이를 나타내고 있었다. 또한 토성별 임도구조는 노폭, 종단물매, 성토길이는 유의적인 차이가 없었으며, 그 이외의 요인은 서로 차이가 있는 것으로 나타났다. 개설위치에 따른 임도구조 변화는 절토경사는 유의적인 차이가 없는 것으로, 그 이외의 요인은 차이가 있는 것으로 나타났다.

• 천문학회지
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• 제38권2호
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• pp.149-151
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• 2005

We have studied the environmental effect on optical-NIR color gradients of 273 nearby elliptical galaxies. Color gradient is a good tool to study the evolutionary history of elliptical galaxies, since the steepness of the color gradient reflects merging history of early types. When an elliptical galaxy goes through many merging events, the color gradient can be get less steep or reversed due to mixing of stars. One simple way to measure color gradient is to compare half-light radii in different bands. We have compared the optical and near infrared half-light radii of 273 early-type galaxies from Pahre (1999). Not surprisingly, we find that $r_e(V)s$ (half-light radii measured in V-band) are in general larger than $r_e(K)s$ (half-light radii measured in K-band). However, when divided into different environments, we find that elliptical galaxies in the denser environment have gentler color gradients than those in the less dense environment. Our finding suggests that elliptical galaxies in the dense environment have undergone many merging events and the mixing of stars through the merging have created the gentle color gradients.

• Journal of Astronomy and Space Sciences
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• 제16권1호
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• pp.1-10
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• 1999

The archival long-slit spectra, covering the wavelength range 4050 ~ 5150 $\AA$, have been used to investigate the radial behavior of absorption line fea-tures (G4300, Fe4383, Ca4455, Fe4531, and $H{\beta}$) of an elliptical galaxy NGC 5846A. The heliocentric recession velocity of NGC 5846 has been derived as $1949{\pm}87\;kms^{-1}$. Fe absorption lines of NGC 5846A show significant radial gradients with the mean slope of $\Delta/Delta(r")=-0.863\pm0.202$. There is also a significant radial gradient of G band with a slope of $-1.109{\pm}0.098$. On the other hand, no radial gradients has been detected on the Ca4455 and $H{\beta}$ absorptions of NGC 5846A. A metallicity gradient, which is derived from the Fe line gradients, is similar to the abundance gradient predicted by Larson's (1975) dissipative models for the formation of elliptical galaxies. We also note that a galaxy-galaxy interaction could affect the line gradients of NGC 5864A.

• 천문학회보
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• 제39권2호
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• pp.53.2-53.2
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• 2014

Radial color gradient of early type galaxies (ETGs) is a key tool for studying the evolution of these galaxies. In this work, we investigated whether ETGs having negative or positive color gradients show any distinguishable characteristics in the galaxy properties. We selected sample of 211 ETGs at 0.01 < z < 0.5 in the Spitzer FLS field, then we constructed u-R color gradients. We obtained the stellar mass, specific star formation rate and fluxes of emission lines of each ETG from MPA-JHU DR7 catalog. Spitzer IRAC and MIPS 24 micron data were used to detect dust emission from the ETGs. Preliminary result shows that less massive galaxies are likely to have positive color gradients, which is probably due to the ongoing star formation in the galaxy core. Almost all AGNs have negative color gradients. This probably is because AGNs are located in relatively massive galaxies with little ongoing star formation. There exists a marginal difference in the percentage of galaxies with PAH emission between ETGs having positive color gradient and negative color gradient. This also supports that ETGs with positive color gradient are galaxies having enhanced star formation.

• 한국지반신소재학회논문집
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• 제8권4호
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• pp.47-51
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• 2009

우리나라의 자연재해는 대부분 풍수해에 의해 발생하며, 강우시 산비탈이 갑작스럽게 붕괴되는 산사태로 인해 큰 재난을 겪고 있다. 사면파괴를 유발하는 요인은 다양하고 요인들이 서로 관련이 있기 때문에 어느 하나의 요인에 의하여 사면파괴의 발생을 설명할 수는 없으나, 외적요인 중 강우는 가장 중요한 외적요인이다. 따라서, 본 논문에서는 무보강된 일반사면과 친환경 호안구조물로 사면보호공법이 적용된 사면을 대상으로 실내 강우재현실험을 수행하였으며, 강우강도와 사면경사에 따른 유출량과 저류량을 분석하여 호안구조물의 침식에 대한 사면보호효과에 대하여 검토하였다.

• Structural Engineering and Mechanics
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• 제83권5호
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• pp.645-654
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• 2022

Environmental thermal loads such as vertical and lateral temperature gradients are significant factors that must be taken into account when designing the bridge. Different models have been developed and used by countries for simulating thermal gradients in bridge codes. In most of the codes only vertical temperature gradients are considered, such as Iranian Standard Loads for Bridge code (ISLB), which only considers the vertical gradient for bridge design proposes. On the other hand, the vertical gradient profile specified in ISLB, has many lacks due to the diversity of climate in Iran, and only one vertical gradient profile is defined for whole Iran. This paper aims to get the both vertical and lateral gradient loads for the concrete box girder using experimental analysis in the capital of Iran, Tehran. To fulfill this aim, thermocouples are installed in experimental concrete segment and temperatures in different location of the segment are recorded. A three dimensional finite element model of concrete box-girder bridge is constructed to study the effects of thermal loads. Results of investigation proved that the effects of thermal loads are not negligible, and must be considered in design processes. Moreover, a solution for reducing the negative effects of thermal gradients in bridges is proposed. Results of the simulation show that using one layer polyurethane insulation can significantly reduce the thermal gradients and thermal stresses.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.78-84
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• 1996

In order to eliminate TPM(Total Particulate Matter) from a diesel engine, we designed and developed a particulate trap system using a burner, which was named as AEFR(Active Exhaust Feeding Regeneration) system. We have considered the temperature distributions and gradients in the filter being regenerated according to regeneration control schemes Ⅰ, Ⅱ and Ⅲ. Schemes Ⅲ has shown the most desirable peak temperature and temperature gradients in AFER system. Finally, it was concluded that much lower peak temperature and temperature gradients in the filter could be obtained than that of other advanced research results by our AEFR system.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제11권4호
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• pp.293-298
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• 2011

In this paper, we propose a new image descriptor, that is, a rotation invariant histogram of oriented gradients (RIHOG). RIHOG overcomes a disadvantage of the histogram of oriented gradients (HOG), which is very sensitive to image rotation. The HOG only uses magnitude values of a pixel without considering neighboring pixels. The RIHOG uses the accumulated relative magnitude values of corresponding relative orientation calculated with neighboring pixels, which has an effect on reducing the sensitivity to image rotation. The performance of RIHOG is verified via the index of classification and classification of Brodatz texture data.

• Journal of Multimedia Information System
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• 제2권1호
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• pp.171-178
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• 2015

This article describes 3 dimensional (3D) face recognition system using histogram of oriented gradients (HOG) based on face curvature. The surface curvatures in the face contain the most important personal feature information. In this paper, 3D face images are recognized by the face components: cheek, eyes, mouth, and nose. For the proposed approach, the first step uses the face curvatures which present the facial features for 3D face images, after normalization using the singular value decomposition (SVD). Fisherface method is then applied to each component curvature face. The reason for adapting the Fisherface method maintains the surface attribute for the face curvature, even though it can generate reduced image dimension. And histogram of oriented gradients (HOG) descriptor is one of the state-of-art methods which have been shown to significantly outperform the existing feature set for several objects detection and recognition. In the last step, the linear discriminant analysis is explained for each component. The experimental results showed that the proposed approach leads to higher detection accuracy rate than other methods.

• 대한수의학회지
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• 제29권1호
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• pp.57-60
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• 1989

This study was carried out to evaluate the possibility of sex preselection by gradients methods using bovine serum albumin in rabbits. Artificial insemination was performed with sperm from the top and bottom layer of rabbit semen separated by bovine serum albumin gradients. Various characteristics of separated sperm, and the conception rate and secondary sex ratio at artificial insemination with separated sperm were compared. The results obtained were as follows. 1. The sperm from the bottom layer showed significanty high value in motility, percent of normal sperm and progressive motility as compared with control sperm and the sperm and the sperm from the top layer. 2. The conception rate of sperm from the bottom layer was higher than that of the top layer. But secondary sex ratio was not altered by this methods.