• 한국재료학회지
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• 제24권11호
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• pp.599-603
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• 2014

$NaLa_{1-x}(MoO_4)_2:Eu^{3+}/Yb^3$ phosphors with doping concentrations of $Eu^{3+}$ and $Yb^{3+}$ ($x= Eu^{3+}+Yb^{3+}$, $Eu^{3+}=0.05$, 0.1, 0.2 and $Yb^{3+}= 0.2$, 0.45) were successfully synthesized by the microwave-modified sol-gel method, and the upconversion and spectroscopic properties were investigated. Well-crystallized particles showed a fine and homogeneous morphology with particle sizes of $2-5{\mu}m$. Under excitation at 980 nm, $NaLa_{0.5}(MoO_4)_2:Eu_{0.05}Yb_{0.45}$ particles exhibited a strong 525-nm emission band and a weak 550-nm emission band in the green region, and a very weak 665-nm emission band in the red region. The strong 525-nm emission in the green region corresponds to the $^7F_1{\rightarrow}^5D_1$ transition and the weak 550-nm emission in the green region corresponds to the $^7F_0{\rightarrow}^5D_2$ transition, while the very weak emission 665-nm band in the red region corresponds to the $^5D_0{\rightarrow}^7F_3$ transition. The Raman spectra of the doped particles indicated the domination of strong peaks at higher frequencies of 762, 890, 1358 and $1430cm^{-1}$ and weak peaks at lower frequencies of 323, 388 and $450cm^{-1}$ induced by the disorder of the $[MoO4]^{2-}$ groups with the incorporation of the $Eu^{3+}$ and $Yb^{3+}$ elements into the crystal lattice or by a new phase formation.

• 대한기계학회논문집B
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• 제33권7호
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• pp.486-494
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• 2009

One-dimensional modeling of $CH_4$/air premixed flame was conducted to validate the heat loss model and investigate NOx formation characteristics in the postflame region. The predicted temperature and NO concentration were compared to experimental data and previous heat loss model results using a constant gradient of temperature (100 K/cm). The following conclusions were drawn. In the heat loss model using steady-state heat transfer equation, the numerical results using the effective heat loss coefficient ($h_{eff}$) of $1.0\;W/m^2K$ were in very good agreement with the experiments in terms of temperature and NO concentration. On the other hand, the calculated values using the constant gradient of temperature (100 K/cm) were lower than that in the experiments. Although the effects of heat loss suppress NO production near the flame region, a significant difference in NO concentration was not found compared to that under adiabatic conditions. In the postflame region, however, there were considerable differences in NO emission index as well as the contribution of NO formation mechanisms. In particular, in the range of ${\phi}\;{\geq}\;0.8$, the prompt NO mechanism plays an important role in the NO reduction under the adiabatic condition. On the other hand, the mechanism contributes to the NO production under the heat loss conditions.

• 한국대기환경학회지
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• 제34권4호
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• pp.517-533
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• 2018

We utilize the CAMx (Comprehensive Air Quality Model with eXtensions) system and the PSAT (Particulate Source Apportionment Technology) diagnostic tool to determine the $PM_{2.5}$ concentration and to perform its source apportionment in the southeastern region of South Korea. For a year-long simulation, eight local authorities in the region such as Pohang, Daegu, Gyeongju, Ulsan, Busan-Gimhae, Gosung-Changwon, Hadong, and all remaining areas in Gyeongsangnam-do, are selected as source areas based on the emission rates of $NO_x$, $SO_x$, VOC, and primary PM in CAPSS (Clean Air Policy Support System) 2013 emissions inventory. The CAMx-PSAT simulation shows that Pohang has the highest $PM_{2.5}$ self-contribution rate (25%), followed by Hadong (15%) and Busan-Gimhae (14%). With the exception of Pohang, which has intense fugitive dust emissions, other authorities are strongly affected by emissions from their neighboring areas. This may be measured as much as 1 to 2 times higher than that of the self-contribution rate. Based on these estimations, we conclude that the efficiency of emission reduction measures to mitigate $PM_{2.5}$ concentrations in the southeastern region of South Korea can be maximized when the efforts of local or regional emission controls are combined with those from neighboring regions. A comprehensive control policy planning based on the collaboration between neighboring jurisdictional boundaries is required.

• 정보처리학회논문지B
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• 제17B권3호
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• pp.239-248
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• 2010

혈액 세포 영상에서 백혈구는 환자의 건강상태를 파악하는데 중요한 정보를 제공하며, 이를 통해 다양한 질병을 조기에 예측할 수 있다. 따라서 질병의 조기 예측을 위해 혈액세포에서 백혈구의 분리는 매우 중요한 단계이다. 본 논문에서는 중요도 맵과 단계적 영역 병합을 이용하여 혈액 세포 영상에서 백혈구를 자동으로 분할하는 기법을 제안한다. 백혈구 세포 영역은 염색물질에 의해 주변에 비해 두드러진 색상, 질감 정보를 가짐으로 이를 기반으로 중요도 맵(Saliency Map)을 만든다. 이를 통해 세포 영상에서 두드러진 영역을 찾아 sub-image를 분리하고, 각 sub-image에서 mean-shift 알고리즘을 적용하여 영역 클러스터링을 수행한다. Mean-shift 적용 후 얻은 클러스터들에 대해 단계적 영역 병합 알고리즘을 적용하고, 최종적으로 백혈구 핵으로 판단되는 단일 클러스터를 얻을 수 있다. 본 논문에서 제안한 방법은 혈액 세포 영상을 사용하여 테스트한 결과 71%의 핵 검출 정확도를 보였으며, 기존의 다른 알고리즘보다 뛰어난 성능을 나타내었다.

• 정보과학회 논문지
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• 제44권7호
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• pp.692-702
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• 2017

LBP기반 특징점 기술자를 이용한 얼굴검출은 얼굴의 형태정보 및 눈, 코, 입과 같은 얼굴 요소들 간 공간정보를 표현할 수 없는 문제가 있다. 이러한 문제를 해결하기 위해 선행 연구들은 얼굴 영상을 다수개의 사각형 부분영역들로 분할하였다. 하지만, 연구마다 서로 다른 개수와 크기로 부분 영역을 분할하였기 때문에 실험에 사용하는 데이터베이스에 적합한 부분 영역의 분할 기준이 모호하며, 부분 영역의 수에 비례하여 LBP 히스토그램 차원이 증가되고, 부분 영역의 개수가 증가함에 따라 얼굴의 방향 회전에 대한 민감도가 크게 증가한다. 본 논문은 LBP기반 특징점 기술자의 방향 회전 문제와 특징점 차원의 수 문제를 해결할 수 있는 새로운 부분 영역 분할 방법을 제안한다. 실험 결과, 제안하는 방법은 방향 회전된 단일 얼굴 영상에서 99.0278%의 검출 정확도를 보였다.

• 천문학회보
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• 제43권1호
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• pp.44.2-44.2
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• 2018

G33.92+0.11, classified as a core-halo UC HII region at a distance of 7.1 kpc, contains several sub-clumps (~20-200 solar masses) as identified by dust continuum emission. This source shows very complicated features associated with vigorous massive star-forming activities with a nearly face-on projection. The ambient gas is still accreting to the massive molecular clumps dynamically, while the whole cloud is under disruption by newly formed stars. Using the recent high resolution (< 0.2") ALMA observations, we investigate the detailed structure associated with the star-forming activities by comparing different chemical tracers. The sub-clumps having extremely complex morphologies still preserve cold dense gas together with the turbulent and dense warm gas resulted by newly formed stars and interaction with accreting gas. The accretion of the ambient gas may have occurred episodically to this source. Most recent star formation, which probably the third generation of star formation in this region, is taking place in the northern part (A5 clump). The relatively small mass (~ 1/3 of A1 or A2) and the lack of turbulent gas of this star-forming core may suggest that this core was formed already during the overall collapse of the whole cloud for the first star formation. We think that gravitational collapse of these sub-clumps appears as sequential star formation of this region. The later interaction with accreting gas may have not been a direct cause of the star formation activities of this source.

• 한국소음진동공학회논문집
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• 제19권10호
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• pp.1069-1074
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• 2009

A sub-domain method for free vibration analysis of arbitrarily shaped, concave membranes with a deep groove is proposed in the paper. The proposed method divides the concave membrane of interest into two convex regions. The vibration displacement(approximate solution) of each convex region is assumed by linearly superposing plane waves generated at edges of the region. A sub-system matrix for each convex region is extracted by applying a provisional boundary condition to the approximate solution. Finally, a system matrix, which of the determinant gives eigenvalues of the concave membrane, is made by considering the fixed boundary condition(displacement zero condition) at edges and the compatibility condition(the condition of continuity in displacement and slope) at the interface between the two regions. Case studies show that the proposed method is valid and accurate when the eigenvalues by the proposed are compared to those by NDIF method, FEM, or the exact method.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.206-212
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• 2011

The effect of process parameters on $H_2$ production from water vapor excited by HF ICP has been qualitatively examined for the first time. With the increase of ICP power, characteristics of $H_2$ production from $H_2O$ dissociation in plasma was divided into 3 regions according to both reaction mechanism and energy efficiency. At the edge of region (II) in the range of middle ICP power, energy effective hydrogen production from $H_2O$ plasma can be achieved. Furthermore, within the region (II) power condition, heating of substrate up to $500^{\circ}C$ shows additional increase of 70~80% in $H_2$ production compared to $H_2O$ plasma without substrate heating. This study have shown that combination of optimal plasma power (region II) and wall heating (around $500^{\circ}C$) is one of effective ways for $H_2$ production from $H_2O$.

• 한국환경과학회지
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• 제22권8호
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• pp.1043-1052
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• 2013

This study was conducted to investigate the correlations between the $PM_{10}$ concentration trend and meteorological elements in the Gimhae region and analyze the transportation routes of air pollutants through back-trajectory analysis. Among the air quality measuring stations in the Gimhae regions, the $PM_{10}$ concentration of the Sambangdong station was higher than that of the Dongsangdong station. Also, an examination of the relationships between $PM_{10}$ concentration and meteorological elements showed that the greater the number of yellow dust occurrence days was and the lower the temperature and precipitation were, the higher the $PM_{10}$ concentration appeared. Furthermore, a cluster analysis through the HYSPLIT model showed that there were 4 clusters of trajectories that flowed into the Gimhae region and most of them originated in China. The meteorological characteristics of the four clusters were analyzed and they were similar to those of the air masses that influence South Korea. These analyses found that meteorological conditions affect the $PM_{10}$ concentration.

• 전자공학회논문지
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• 제50권9호
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• pp.55-59
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• 2013

Sub-$0.1{\mu}m$로 스케일이 감소함에 따라 기생 저항 효과가 크게 발생되는 dc Ids 측정 데이터 없이 측정 S-파라미터로부터 얻어진 RF Ids를 사용하여 벌크 MOSFET의 포화영역에서 게이트 전압 종속 유효 캐리어 속도를 추출하는 새로운 방법이 개발되었다. 이 방법은 바이어스 종속 기생 게이트-소스 캐패시턴스와 유효 채널 길이의 복잡한 추출 없이 포화영역의 유효 캐리어 속도를 추출할 수 있게 한다. 이러한 RF 기술을 사용하여 벌크 포화 속도를 초과하는 전자 속도 overshoot 현상이 $0.065{\mu}m$ 게이트 길이의 벌크 N-MOSFET에서 관찰되었다.