• 한국유변학회:학술대회논문집
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• 한국유변학회 2001년도 Australian-Korean Rheology Conference 2001
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• pp.164.3-164
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• 2001

• 한국정보처리학회논문지
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• 제2권4호
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• pp.535-542
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• 1995

이 논문에서 우리는 CM-5와 같은 초대형병렬컴퓨터에서 대형 이산선형체제를 풀기 위한 준비행렬로써 두 가지를 소개한다. 대다수의 초대형병렬컴퓨터들은 프로세서간의 통신을 메세지패씽(messagepassing)에 의존하는데 현재의 기술수준하에서는 이 통신속 도가 실수계산속도에 비해 매우 느리므로 종래의 메모리공유컴퓨터에서와는 달리 데이 터통신량을 최소화하는 알고리듬이 요구된다. 블록 SOR에 다중색채기법을 가미한 알고 리듬이 그 한 예로써 우리는 이를 CM-5에서 구현한 결과 N=512x512 행렬에서 프로세서 의 수가 16에서 512의 범위 하에서 50%의 효율을 실현하였다. 반면 종래의 효율적인 병렬 준비행렬로 알려진 AKI알고리듬은 방대한 량의 데이터통신 때문에 매우 열등한 결과를 보여준다.

• 한국환경과학회지
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• 제26권6호
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• pp.767-778
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• 2017

This research investigates the characteristics of metallic and ionic elements in $PM_{10}$ and $PM_{2.5}$ on haze day and non-haze day in Busan. $PM_{10}$ concentration on haze day and non-haze day were 85.75 and $33.52{\mu}g/m^3$, respectively, and $PM_{2.5}$ on haze day and non-haze day were 68.24 and $23.86{\mu}g/m^3$, respectively. Contribution rate of total inorganic water-soluble ion to $PM_{10}$ mass on haze day and non haze day were 58.2% and 61.5%, respectively, and contribution rate of total water-soluble ion to $PM_{2.5}$ mass on haze day and non haze day were 58.7% and 64.7%, respectively. Also, contribution rate of secondary ion to $PM_{10}$ mass on haze day and non haze day were 52.1% and 47.5%, respectively, and contribution rate of secondary ion to $PM_{2.5}$ mass on haze day and non haze day were 54.4% and 53.6%, respectively. AC (anion equivalents)/CE (cation equivalents) ratio of $PM_{10}$ mass on haze day and non haze day were 1.09 and 1.0, respectively, and AC/CE ratios of $PM_{2.5}$ mass on haze day and non haze day were 1.12 and 1.04, respectively. Also, SOR (Sulfur Oxidation Ratio) of $PM_{10}$ mass on haze day and non haze day were 0.32 and 0.17, respectively, and SOR of $PM_{2.5}$ on haze day and non haze day were 0.30 and 0.15, respectively. Lastly, NOR (Nitrogen Oxidation Ratio) of $PM_{10}$ on haze day and non haze day were 0.17 and 0.08, respectively, and NOR of $PM_{2.5}$ on haze day and non haze day were 0.13 and 0.06, respectively.

• Korean Chemical Engineering Research
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• 제46권6호
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• pp.1039-1042
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• 2008

폐폴리우레탄의해중합에의하여제조된재생폴리올의작용기를증가시키기위하여해중합시첨가한 pentaerythritol(PEN, 작용기(f)=4) 또는 sorbitol(SOR, f=6)이 생성된 재생 폴리올의 작용기와 이를 사용하여 제조한 경질 폴리우레탄폼(polyurethane rigid foam; PUR)의 기계적 물성에 미치는 영향을 조사하였다. PEN 또는 SOR를 첨가한 경우 OH 작용기가 2.2에서 약 2.8로 증가하였고, PUR의 치수안전성 등을 비롯한 기계적 물성이 크게 향상됨을 확인하였다. 이러한 결과는 폴리올의 작용기가 증가하여 제조한 PUR의 가교밀도를 향상시킨 것으로 해석되었다. 또한 재생 폴리올의 폴리올 시스템에 대한 사용량을 8 wt%에서 약 20 wt%로 증가시킬수 있었다.

• Journal of applied mathematics & informatics
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• 제25권1_2호
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• pp.435-443
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• 2007

Computing the interior spectrum of large sparse generalized eigenvalue problems $Ax\;=\;{\lambda}Bx$, where A and b are large sparse and SPD(Symmetric Positive Definite), is often required in areas such as structural mechanics and quantum chemistry, to name a few. Recently, CG-type methods have been found useful and hence, very amenable to parallel computation for very large problems. Also, as in the case of linear systems proper choice of preconditioning is known to accelerate the rate of convergence. After the smallest eigenpair is found we use the orthogonal deflation technique to find the next m-1 eigenvalues, which is also suitable for parallelization. This offers advantages over Jacobi-Davidson methods with partial shifts, which requires re-computation of preconditioner matrx with new shifts. We consider as preconditioners Incomplete LU(ILU)(0) in two variants, ever-relaxation(SOR), and Point-symmetric SOR(SSOR). We set m to be 5. We conducted our experiments on matrices from discretizations of partial differential equations by finite difference method. The generated matrices has dimensions up to 4 million and total number of processors are 32. MPI(Message Passing Interface) library was used for interprocessor communications. Our results show that in general the Multi-Color ILU(0) gives the best performance.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1798-1803
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• 2003

In this work the dynamic heat transfer occurring in a cable penetration fire stop system built in the firewall of nuclear power plants is three-dimensionally investigated to develop a test-simulator that can be used to verify effectiveness of the sealants. The dynamic heat transfer can be described by a partial differential equation (PDE) and its initial and boundary conditions. For the shake of simplicity PDE is divided into two parts; one corresponding to the heat transfer in the axial direction and the other corresponding to the heat transfer on the vertical layers. Two numerical methods, SOR (Sequential Over-Relaxation) and FEM (Finite Element Method), are implemented to solve these equations respectively. The axial line is discretized, and SOR is applied. Similarly, all the layers are separated into finite elements, where the time and spatial functions are assumed to be of orthogonal collocation state at each element. The heat fluxes on the layers are calculated by FEM. It is shown that the penetration cable influences the temperature distribution of the fire stop system very significantly. The simulation results are shown in the three-dimensional graphics for the understanding of the transient temperature distribution in the fire stop system.

• 대한방사성의약품학회지
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• 제3권2호
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• pp.65-71
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• 2017

To assess the effects of filter and reconstruction of Cu-64 PET data on Siemens scanner, the various reconstruction algorithm with various filters were assessed in terms of spatial resolution, non-uniformity (NU), recovery coefficient (RC), and spillover ratio (SOR). Image reconstruction was performed using filtered backprojection (FBP), 2D ordered subset expectation maximization (OSEM), 3D reprojection algorithm (3DRP), and maximum a posteriori algorithms (MAP). For the FBP reconstruction, ramp, butterworth, hamming, hanning, or parzen filters were used. Attenuation or scatter correction were performed to assess the effect of attenuation and scatter correction. Regarding spatial resolution, highest achievable volumetric resolution was $3.08mm^3$ at the center of FOV when MAP (${\beta}=0.1$) reconstruction method was used. SOR was below 4% for FBP when ramp, Hamming, Hanning, or Shepp-logan filter were used. The lowest NU (highest uniform) after attenuation & scatter correction was 5.39% when FBP (parzen filter) was used. Regarding RC, 0.9 < RC < 1.1 was obtained when OSEM (iteration: 10) was used when attenuation and scatter correction were applied. In this study, image quality of Cu-64 on Siemens Inveon PET was investigated. This data will helpful for the quantification of Cu-64 PET data.

• Environmental Engineering Research
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• 제20권3호
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• pp.298-305
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• 2015

The Standards for Water Works issued by the Korean government prescribed the insertion of inclined plates in a clarifier to enhance the settling of the suspended solids. In this study, in order to verify the role of the inclined plates, two identical laboratory-scale rectangular clarifiers were constructed and eight inclined plates were inserted into one of the clarifiers and inflow from same source was treated in both the clarifiers. Dye tests revealed that only the front three of the seven slots received the inflow at $0.57m^3/m^2{\cdot}h$, which was the highest SOR (surface overflow rate). Three different SORs, with 12 different SS (suspended solid) concentrations at each overflow rate, were fed to both clarifiers. However, the clarifier with the inclined plates failed to show an improved removal rate for the SS. In order to enable the Boycott effect within the slot, it is suggested that each slot created by the inclined plates receives equalized inflow. Moreover, collision of the inflow with the settled sludge at the bottom of the clarifier has to be avoided. These provisions, which can maximize the Boycott effect, should be added to the Standards for Water Works endorsed by Korean government.

• 지식경영연구
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• 제14권4호
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• pp.1-17
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• 2013

As online communities proliferate, online news sites have received great attention in news media research. Although most of the online news sites provide contents for free, some have adopted the Pay-What-You-Want (PWYW) model by offering a voluntary payment option to the readers. In this study, we investigate the factors which influence subscribers' voluntary payment behavior on an online news site. Drawing upon both the Stimulus-Organism-Response (SOR) framework and the Elaboration Likelihood Model (ELM), we hypothesize that appreciation has a direct effect on the subscribers' voluntary payment behavior, whereas central factors (positive emotional content, cognitive content) and peripheral factors (news sharing, news article length) of the news articles have indirect impacts on voluntary payment behavior through the enhanced appreciation. Based on an empirical analysis of 172 news articles from the Korean online news site that adopted the PWYW pricing model (i.e., Ohmynews.com), we find that appreciation plays a critical role in voluntary payment behavior and that peripheral factors have significant impacts on appreciation. However, the impacts of central factors on appreciation are not found. By identifying influencing factors of subscribers' voluntary payment behavior on online news sites for the first time, this paper suggests a prospective alternative profit model for online news providers faced with fierce competition.

• Journal of Preventive Medicine and Public Health
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• 제48권5호
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• pp.225-230
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• 2015

Objectives: The epidemiological characteristics of breast cancer incidence by age group in Korean women are unique. This systematic review aimed to investigate the association between hormone replacement therapy (HRT) and breast cancer risk in Korean women. Methods: We searched electronic databases such as KoreaMed, KMbase, KISS, and RISS4U as well as PubMed for publications on Korean breast cancer patients. We also conducted manual searching based on references and citations in potential papers. All of the analytically epidemiologic studies that obtained individual data on HRT exposure and breast cancer occurrence in Korean women were selected. We restricted the inclusion of case-control studies to those that included age-matched controls. Estimates of summary odds ratio (SOR) with 95% confidence intervals (CIs) were calculated using random effect models. Results: One cohort and five case-control studies were finally selected. Based on the heterogeneity that existed among the six studies (I-squared=70.2%), a random effect model was applied. The summary effect size of HRT history from the six articles indicated no statistical significance in breast cancer risk (SOR, 0.983; 95% CI, 0.620 to 1.556). Conclusions: These facts support no significant effect of HRT history in the risk of breast cancer in Korean women. It is necessary to conduct a pooled analysis.