• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1350-1364
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• 2023

2D/1D coupling method is an important neutron transport calculation method due to its high accuracy and relatively low computation cost. However, 2D/1D coupling method may diverge especially in small axial mesh size. To analyze the convergence behavior of 2D/1D coupling method, a Fourier analysis for k-eigenvalue neutron transport problems is implemented. The analysis results present the divergence problem of 2D/1D coupling method in small axial mesh size. Several common attempts are made to solve the divergence problem, which are to increase the number of inner iterations of the 2D or 1D calculation, and two times 1D calculations per outer iteration. However, these attempts only could improve the convergence rate but cannot deal with the divergence problem of 2D/1D coupling method thoroughly. Moreover, the choice of axial solvers, such as DGFEM SN and traditional SN, and its effect on the convergence behavior are also discussed. The results show that the choice of axial solver is a key point for the convergence of 2D/1D method. The DGFEM SN based 2D/1D method could converge within a wide range of optical thickness region, which is superior to that of traditional SN method.

• 디지털융복합연구
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• 제15권10호
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• pp.357-366
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• 2017

본 연구는 한국 여성의 비타민 D 결핍에 영향을 미치는 요인을 파악하여 한국 여성의 비타민 D 관리를 위한 기초자료를 제시하고자 시도되었다. 본 연구는 제5기 국민건강영양조사 자료를 활용하였으며 만 19세 이상 여성을 대상으로 인구사회학적 특성, 건강관련 특성, 혈중 비타민 D를 파악하였다. 자료 분석은 IBM SPSS 18.0 프로그램을 이용하여 복합표본 설계를 적용하였다. 연구 결과 한국 여성의 비타민 D 결핍률은 81.4%였으며 비타민 D 결핍군과 정상군은 연령, 결혼 여부, 거주 지역, 주거유형, 소득수준, 교육수준에 따라 유의한 차이가 있었다. 비타민 D 결핍 영향요인을 분석한 결과 비타민 D 결핍 위험은 65세 이상 집단보다 19~39세 집단이 2.5배 높았으며 기혼에 비해 미혼인 경우 2배 높았다. 걷기를 실천하지 않는 경우 1.5배, 스트레스를 많이 느끼는 경우 1.5배 비타민 D 결핍 위험이 높았다. 본 연구의 결과에 따라 연령대별 비타민 D 결핍 위험 요인을 밝히기 위한 추후 연구가 필요하며 비타민 D 결핍 예방을 위해 여성의 스트레스 완화와 신체활동 증진이 필요하겠다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.124-130
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• 2001

The heat transfer and flow measurements were made on a cylindrical pedestal mounted on a flat plate with a turbulent impinging air jet. The heat transfer coefficient distributions on the flat plate were measured using the shroud-transient technique and liquid crystal was used to measure the surface temperature. The jet Reynolds number (Re) is 23,000, the dimensionless nozzle-to-surface distance (L/d) from 2 to 10, the dimensionless pedestal diameter-to-height (H/D) from 0 to 1.5, the dimensionless 2nd pedestal diameter-to-height ($H/D_2$) from 0 to 0.4 and the distance from the stagnation point to 2nd pedestal (p/D). The results show that for H/D = 0.5 to 1.5, the Nusselt number distributions on the plate surface exhibit a maximum between $r/d\;{\cong}\;1.0$ and 1.5. The presence of the pedestal appears to cause the flow separation and reattachment on the plate surface, which results in the maximum heal transfer coefficient. Also, for p/D = 2.5 and $H/D_2$ = 0.3, the local Nusselt number in the region corresponding to $r/d\;{\cong}\;1.1$ was increased up to 50% compared to that for $H/D_2=0$.

• 로봇학회논문지
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• 제12권1호
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• pp.33-41
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• 2017

We present a region-based approach for accurate pose estimation of small mechanical components. Our algorithm consists of two key phases: Multi-view object co-segmentation and pose estimation. In the first phase, we explain an automatic method to extract binary masks of a target object captured from multiple viewpoints. For initialization, we assume the target object is bounded by the convex volume of interest defined by a few user inputs. The co-segmented target object shares the same geometric representation in space, and has distinctive color models from those of the backgrounds. In the second phase, we retrieve a 3D model instance with correct upright orientation, and estimate a relative pose of the object observed from images. Our energy function, combining region and boundary terms for the proposed measures, maximizes the overlapping regions and boundaries between the multi-view co-segmentations and projected masks of the reference model. Based on high-quality co-segmentations consistent across all different viewpoints, our final results are accurate model indices and pose parameters of the extracted object. We demonstrate the effectiveness of the proposed method using various examples.

• 한국전기전자재료학회논문지
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• 제28권4호
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• pp.213-217
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• 2015

Device model parameters are very important for accurate estimation of electrical performances in devices, integrated circuits and their systems. There are a large number of methods for extraction of model parameters in power MOSFETs. For high efficiency, design is important considerations of a power MOSFET with high-voltage applications in consumer electronics. Meanwhile, it was proposed that the efficiency of a MOSFET can be enhanced by conducting JFET region double implant to reduce the On-resistance of the transistor. This paper reports the effects of JFET region double implant on the electrical properties and the decreasing On-resistance of the MOSFET. Experimental results show that the 1st JFET region implant diffuse can enhance the On-resistance by decreasing the ion concentration due to the surface and reduce the On-resistance by implanting the 2nd Phosphorus to the surface JFET region.

• 한국지구과학회지
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• 제38권7호
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• pp.511-521
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• 2017

본 연구는 우적크기분포의 통계적 특성과 변동성을 알아보기 위하여, 2011-2012년 대구지역 2차원광학우적계자료를 분석하여 Marshall and Palmer(1948)의 우적크기분포 특성과 비교하였다. 우적크기분포의 특성변수로 강우강도(R), 레이더 반사도(Z), 보편특성수농도($N{_0}^{\prime}$), 보편특성직경($D{_m}^{\prime}$)을 계산하였다. 또한 스케일링 법칙을 사용하여 우적크기분포의 정규화 여부를 확인하였다. 분석 결과, 대구지역의 우적크기분포는 평균적으로 ${\log}_{10}N{_0}^{\prime}=2.37$, $D{_m}^{\prime}=1.04mm$이며 형태 인자의 경우 c =2.37, ${\mu}=0.39$를 가졌다. 대구지역의 우적크기분포를 Marshall and Palmer의 우적크기분포로 가정하여 계산한 결과, 평균적으로 ${\log}_{10}N{_0}^{\prime}=2.27$, $D{_m}^{\prime}=0.9mm$, c =1, ${\mu}=1$를 가졌다. 이 차이로부터 대구지역 우적크기분포는 Marshall and Palmer(1948)의 우적크기분포보다 통계적으로 더 높은 액체수함량을 가짐을 알 수 있다. 우적크기분포의 형태를 비교한 결과, 대구지역 우적크기분포는 위로 볼록한 모양이었다. Z > 45 dBZ를 기준으로 우적크기분포 형태에 변화가 있었다. 35 dBZ ${\leq}$ Z > 45 dBZ에서 대구지역 우적크기분포 특성은 해양성 기후대와 유사하였으나 Z > 45 dBZ에서는 Marshall and Palmer의 우적크기분포 특성과 유사하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제23권2호
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• pp.253-262
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• 2010

This study aimed to evaluate the nutritional situation of pigs kept in three ecological zones of central Vietnam: Upland, Lowland and Coastal Area. An interview-based questionnaire was made and surveys were conducted in 27 villages and data were collected from 1,200 participating households. The current study showed that amounts of feed and crude protein content in the diets for fattening pigs and sows are deficient for all three regions. Amounts of feed as DM (kg/d) fed to growing pigs of 20-50 kg BW was deficient by 0.54 kg (29%) in Lowland, 0.53 kg (28.6%) in the Coastal area and 0.42 kg (22.4%) in Upland. The deficiency in CP in the diets of growing pigs in this period (20-50 kg) was largest at 20.7 g/d (62.1%) in Lowland, following by 22.1 g/d (66.4%) in Coastal and 23.2 g/d (69.7%) in Upland. Amount of feed as DM (kg/d) fed to growing pigs of 50-90 kg BW had a deficiency of 1.26 (48.9%), 1.25 (51.2%) and 1.14 (51.5%) kg/d in Lowland, Coastal and Upland, respectively. The deficiencies in crude protein in the growing diet during this period in Lowland, Coastal and Upland regions were 27 g/d (68.3%), 29 g/d (71.9%) and 30 g/d (74.6%), respectively. The deficiency in DM intake (kg/d) of pregnant sows in the Lowland area was 0.3 kg (15%), 0.33 kg (16%) in the Coastal area and 0.47 kg (23.5%) in the Upland area. Crude protein content in the diet of pregnant sows raised in Lowland was 8 g/d (32.0%) deficient, in the Coastal region the deficiency was 11 g/d (42.7%) and in Upland this deficiency was 15 g/d (61.2%). The deficiency in DM intake (kg/d) of lactating sows raised in Lowland was 1.47 kg (31.1%), in the Coastal area this was 1.69 kg (39.2%) and in Upland it was most deficient at 2.46 kg (57.1%). The lack of crude protein content in the diets of sows raised in Lowland was 45 g/d (63.4%), in the Coastal region it was 46 g/d (65%), and in Upland it was 55 g/d (78.9%). The low input of feed in these areas is especially due to low quality and to the insufficient intake of nutrients by the pig. As a result, production and income of farmers are low.

• 한국동물위생학회지
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• 제34권2호
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• pp.103-109
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• 2011

Asia1/Shamir that has been recommended by World Reference Laboratory for foot-and-mouth disease (FMD) is used as a vaccine strain, and is being prepared in many countries including Korea. Although it is assumed that vaccine strain Asia1/Shamir has a wide antigenicity, sufficient molecular biological analysis has not been accomplished yet. Complete genome sequence analysis showed that the region with the most severe variations was 1D region of structural protein-coding sequence; particularly amino acid 141~157 residues in 1D region RGD sites for binding to susceptible cells. In addition, five amino acids in 1D region were identified as characteristic sites that are different from other known Asia1 viruses. Asia1/Shamir strain was shown to be genetically similar to group VI that had occurred in the Middle East, but showed low level of genetic similarity to the group V viruses that had occurred in the Southeast Asia and China. It is considered that, if these viruses, group I and II including group V are introduced into Korea, care would be paid in case of inoculating the vaccine strain Shamir available in Korea.

• 한국산학기술학회논문지
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• 제10권5호
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• pp.1026-1033
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• 2009

본 연구에서는 안성천 유역을 대상으로 토지지용별로 산지, 농경지, 도시지역을 표본지역으로 선정하여 비점오염원 원단위를 산정하였다. 그리고 강우시 유출수의 유출특성을 가장 잘 반영하는 유량가중평균농도를 산정하고, 유출오염부하량을 산정하였다. 유출계수가 높게 나타났던 1차 강우시가 2차 강우시보다 오염물질의 유량가중평균농도가 높게 나타나는 경향을 보였으며, 토지이용별 산정결과, 농지와 산지 같은 비도시지역보다 도시 지역에서 강우 유출시 높은 농도의 오염물질이 발생하는 것으로 나타났다. BOD 유출부하량은 산지, 농지, 도시 지역에서 1차 강우 시 각각 1,395kg/d, 1,623kg/d, 2,268kg/d로, 2차 강우시 각각 503kg/d, 512kg/d, 898kg/d로 산정되었다. 강우량 및 강우강도에 따라 토지이용별로 유출부하가 크게 다르게 나타났다. 토지이용별 원단위는 BOD 기준으로 도시지역이 72.7kg/ha/yr로 농경지(6.5kg/ha/yr)보다 12배 이상, 산지(9.5kg/ha/yr)보다 8배 이상 높게 나타나 도시지역이 비도시지역보다 단위면적당 비점오염부하가 매우 높은 것으로 나타났다.

• 천문학회보
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• 제36권2호
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• pp.54.2-54.2
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• 2011

We present a study of HII regions in M51 using HST/ACS images taken as part of the Hubble Heritage Program. We found about 19,600 HII regions in M51 with $H_{\alpha}$ luminosity in the range of $L=10^{35.5}-10^{39.0}\;erg\;s^{-1}$. The $H_{\alpha}$ luminosity function of HII regions (HII LF) in M51 is well represented by a double power law with its index ${\alpha}=-2.25{\pm}0.02$ for the bright part and ${\alpha}=-1.42{\pm}0.01$ for the faint part, separated at a break point $L=10^{37.1}\;erg\;s^{-1}$. Comparison with simulated HII LFs suggests that this break is caused by the transition of HII region ionizing sources, from low-mass clusters (including several OB stars) to more massive clusters (including several tens of OB stars). The HII LFs with L < $10^{37.1}\;erg\;s^{-1}$ are found to have different slopes for different parts in M51: the HII LF for the interarm region is steeper than those for the arm and the nuclear regions. This observed difference in HII LFs can be explained by evolutionary effects: HII regions in the interarm region are relatively older than those in the other parts of M51. The size distribution of the HII regions is fitted by a double power law with a break at D = 30 pc. The power law index for the small HII regions with 15 pc < D < 30 pc is ${\alpha}=-1.78{\pm}0.04$, whereas ${\alpha}=-5.04{\pm}0.08$ for the large HII region with 30 pc < D < 110 pc. The power law indices of the size distribution are related with those of HII LF, and the relation between the luminosities and sizes of HII regions is fitted well by $L{\propto}D^{3.04{\pm}}$.