• 한국경영과학회지
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• 제27권3호
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• pp.145-156
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• 2002

Business managers are often required to use LP problems to deal with uncertainty inherent in decision making due to rapid changes in today＇s business environments. Uncertain parameters can be easily formulated in the two-stage stochastic LP problems. However, since solution methods are complex and time-consuming, a common approach has been to use modified formulations to provide upper and lower bounds on the two-stage stochastic LP problem. One approach is to use an expected value problem, which provides upper and lower bounds. Another approach is to use “walt-and-see” problem to provide upper and lower bounds. The objective of this paper is to propose a modified approach of “wait-and-see” problem to provide an upper bound and to compare the relative error of optimal value with various upper and lower bounds. A computing experiment is implemented to show the relative error of optimal value with various upper and lower bounds and computing times.

• 한국정밀공학회지
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• 제13권8호
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• pp.175-183
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• 1996

This paper presents three-dimensional robot task using the vision control method. A minimum of two cameras is required to place points on end dffectors of n degree-of-freedom manipulators relative to other bodies. This is accomplished using a sequential estimation scheme that permits placement of these points in each of the two-dimensional image planes of monitoring cameras. Estimation model is developed based on a model that generalizes known three-axis manipulator kinematics to accommodate unknown relative camera position and orientation, etc. This model uses six uncertainty-of-view parameters estimated by the iteration method.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.140-140
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• 2022

Recently an accurate quantification of streamflow under various climatological and anthropogenic factors and separation of their relative contribution remains challenging, because variation in streamflow may result in hydrological disasters. In this study, we evaluated the factors responsible for variation in streamflow in Korean watersheds, quantified separately their contribution using different Budyko-based functions, and identified hydrological breakpoint points. After detecting that the hydrological break point in 1995 and time series were divided into natural period (1966-1995), and disturbed period (1996-2014). During the natural period variation in climate tended to increase change in streamflow. However, in the disturbed period both climate variation and anthropogenic activities tended to increase streamflow variation in the watershed. Subsequently, the findings acquired from different Budyko-based functions were observed sensitive to selection of function. The variation in streamflow was observed in the response of change in climatic parameters ranging 46 to 75% (average 60%). The effects of anthropogenic activities were observed less compared to climate variation accounts 25 to 54% (average 40%). Furthermore, the relative contribution was observed to be sensitive corresponding to Budyko-based functions utilized. Moreover, relative impacts of both factors have capability to enhance uncertainty in the management of water resources. Thus, this knowledge would be essential for the implementation of water management spatial and temporal scale to reduce the risk of hydrological disasters in the watershed.

• 대기
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• 제26권3호
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• pp.473-482
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• 2016

An accurate determination of turbulent fluxes over an urban area is a challenging task due to its morphological diversity and associated flow complexity. In this study, an eddy covariance (EC) method is applied over a highly heterogeneous urban area in a small city (Gongju), South Korea to investigate the quantitative influence of 'coordinate tilt' in determining the turbulent fluxes of sensible heat, latent heat, momentum, and carbon dioxide mass. Two widely-used coordinate transform methods are adopted and applied to eight directional sections centered on the site to analyze a 1-year period EC measurement obtained from the urban site: double rotation (DR) and planar fit (PF) transform. The results show that mean streamline planes determined by the PF method are distinguished from the sections, representing morphological heterogeneity of the site. The sectional pitch angles determined by the DR method also compare well with those in the PF method. Both the PF and DR methods show large variabilities in the determined streamline planes at each directional section, implying that flow patterns may form in a complicate way due to the surface heterogeneity. Resulting relative differences of the turbulent fluxes, defined by $(F_{DR}-F_{PF})/F_{DR}$, are found on average +13% in sensible heat flux, +21% in latent heat flux, +37% in momentum flux, and +26% in carbon dioxide mass flux, which are larger values than those reported previously for fairly homogeneous natural sites. The fractional differences depend significantly on wind direction, showing larger differences in northerly winds at the measurement site. It is also found that the relative fractional differences are negatively correlated with the mean wind speed at both stable/unstable atmospheric conditions. These results imply that EC turbulent fluxes determined over heterogeneous urban areas should be carefully interpreted with considering the uncertainty due to 'coordinate tilt' effect in their applications.

• 대한토목학회논문집
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• 제31권1B호
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• pp.21-27
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• 2011

유출예측량을 모의할 때 과거와 현재의 수문자료를 이용한다는 측면에서 미래 예측결과의 불확실성을 완전히 제거할 수는 없겠지만, 다양한 기법별 분석에 의하여 불확실성을 감소시킬 수 있다. 본 연구에서는 유출예측의 정확성 향상을 위해 다양한 유출예측 기법을 적용 및 평가하였으며 확률론적 예측을 가능하게 하는 예측기법인 ESP와 관측 시계열 자료를 이용한 통계기법으로 공주지점의 유출예측을 수행하였다. 각 기법에 따른 유출예측 결과의 신뢰성 평가는 MAE(Mean Absolute Error), RMSE(Root Mean Squared Error), RRMSE(Relative Root Mean Squared Error), Mean Absolute Percentage Error (MAPE), TIC(Theil Inequality Coefficient)를 이용하였다. ESP 확률을 이용하여 예측한 유출결과와 통계적 시계열 분석에 의해 예측된 유출결과를 MAE, RMSE, RRMSE, MAPE, TIC를 이용하여 비교 분석하였으며 유출예측의 개선효과를 확인해본 결과, ESP 확률을 이용한 예측이 MAE(10.6), RMSE(15.14), RRMSE(0.244), MAPE(22.74%), TIC(0.13)으로 평가되었으며 MAE(23.2), RMSE(37.13), RRMSE(0.596), MAPE(26.69%), TIC(0.30)으로 평가된 ARMA와 MAE(26.4), RMSE(34.44), RRMSE(0.563), MAPE(47.38%), TIC(0.25)으로 평가된 Winters 에 비해 신뢰성이 높게 나타났다.

• 한국수자원학회논문집
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• 제50권8호
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• pp.563-577
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• 2017

기후변화로 인해 강수의 불확실성이 증가하는 현 시점에서 효율적인 물 관리를 위한 계절예측 및 기상 예보의 활용은 필수적이다. 본 연구에서는 기상청에서 2014년 6월부터 시행하고 있는 범주형 확률장기예보를 Hit Rate, Reliability Diagram, Relative Operating Curve (ROC)의 평가지표를 활용하여 예측력을 검증하였고, 추가적으로 확률예보를 활용하여 정량적인 예측 강수량을 생산하는 기법을 제안하였다. 확률장기예보의 예측력 검증결과 최대 48%의 예측력을 갖는 것을 확인할 수 있었다. 확률예보를 활용하여 예측 강수량을 추정한 결과, 정량적으로 관측 자료와 유사하게 모의되는 것을 확인할 수 있었으며 예측 적합도 평가결과 100%의 정확도를 가진 예보의 경우 최대 0.98, 실제 예보의 경우 최대 0.71의 상관계수를 보였다. 본 연구에서 제안하는 확률예보를 활용한 예측 강수량 추출기법은 강수의 불확실성을 고려한 물 관리를 가능하게 해줄 것으로 판단되며 효율적인 수자원 장기 이수계획 및 저수지 운영의 의사결정지원 등에 활용 가능할 것으로 기대된다.

• 분석과학
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• 제25권1호
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• pp.83-90
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• 2012

소변 중 크레아티닌의 정상적인 농도범위는 30 - 300 mg/dL로 마약류 감정에 앞서 크레아티닌농도를 측정함으로써 소변 시료의 유효성을 확인하고 있다. 크레아티닌 농도 측정을 위해 액체크로마토그래피-질량분량분석법(LC-MS/MS, liquid chromatography-tandem mass spectrometry)을 사용하였다. 우선 소변 시료를 고속으로 원심분리한 후 10 ${\mu}L$를 분취하여 증류수 390 ${\mu}L$와 혼합하여 희석하였다. 희석된 시료 20 ${\mu}L$에 내부표준물질(5 ${\mu}g/mL$) 30 ${\mu}L$와 acetonitrile 10 ${\mu}L$를 첨가하여 혼합한 후 여과한 시료를 LC-MS/MS에 주입하였다. 크레아티닌은 multi-mode ODS column (Scherzo SM-C18, 75 ${\times}$ 2.0 mm, I.D. 3 ${\mu}m$)을 이용하여 분리하였고, 이동상은 0.2% formic acid와 acetonitrile로 구성되었으며 유속은 150 ${\mu}L$/min으로 하였다. 크레아티닌과 내부표준물질은 [M+H]$^+$ precursor ion과 특징적인 product ion을 한 쌍으로 m/z 114.0${\rightarrow}$ 86.0과 m/z 117.0${\rightarrow}$ 89.1에서 모니터링하여 정량에 적합한 크로마토그램을 얻을 수 있었다. 측정불확도 평가에 앞서 정량분석시 측정값에 영향을 주는 인자들을 찾아내고 각각의 요소들이 측정결과에 어떤 영향을 주는가를 살펴보았다. 시료 희석, 검정 곡선, 재현성, 표준물질의 인자 순으로 측정불확도에 영향을 미치고 있음을 확인하였다. 실제 사람의 소변에서 크레아티닌 농도를 측정한 결과, 측정값에 대한 오차 범위의 상대불확도는 14.2%로 산출되었다.

• 산업경영시스템학회지
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• 제43권3호
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• pp.216-227
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• 2020

The purpose of this paper is to identify a relative importance and priority of the factors of Competencies of project team member. It aims to present the differential competency factors from a differentiated perspective by applying the Leadership Development Questionnaire, which is the competency dimension required for manager, to team member. (1) Background: The diverse needs of customers and companies, and the uncertainty, complexity, ambiguity, and volatility of the environment surrounding the company in the era of the Fourth Industrial Revolution threaten the survival of company. In this respect, companies should implement the project management approach and strive to increase the capabilities of each team member. (2) Methods: AHP method was used to prioritize which factors were considered more importance level and the gap of relative importance level between project manager group and team members group. (3) Results: In the analysis of the relative importance of the upper class, weights were derived in the order of managerial competence, intellectual competence, and emotional competence. The sub-factor that respondents prioritize was communication as the 1st priority, and it was analyzed in the order of strategic perspective, achieving, critical analysis and judgement, and vision and imagination. There were some differences in the ranking of the relative importance of achieving and vision and imagination attributes between the PM group and TM group, it was analyzed that there was no significant difference overall. (4) Implications: The results of this study confirmed the recognition that team members are required to have the same competencies as the project manager. And based on the priorities of the competencies required of team members, companies are expected to cultivate professional and competent team members, and expand the roles and authority of team members so that they can actively carry out projects.

• 한국실내디자인학회논문집
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• 제17권1호
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• pp.77-83
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• 2008

MVRDV is most important architect as created interesting architectural space in contemporary architecture, and so they applies to the unique theory in their architecture. They used to architectural diagram, program, datascape, density as a design tool. Especially, they have create new architectural space and form in using architectural diagram, program, datascape, density, and void. So, this study is purposed to explain how they use as architectural tool to make composition of it's architectural space and is purpose to explain what is their main concept in architectural space. MVRDV's architectural space has fundamental methodology. That is Datascape on uncertainty and continuity between urban space and architectural space. The former consist in using diagram and architectural program and the latter consist in operating architectural void and inner continuity surface. The conclusion is follows 1. The mode of spacial composition by architectural void is correspond density of city as MVRDV's architectural thinking. 2. The mode of spacial composition by architectural program is ambiguous to the boundary between inner and exterior space by transparency. 3. The mode of spacial composition by architectural diagram make to generate the architectural form and space, through the reinterpretation and relocation of architectural program. 4. The mode of spacial composition inner continuity plane is make relative between site and inner space.

• Wind and Structures
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• 제22권1호
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• pp.17-41
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• 2016

To address the uncertainty of the flight trajectories caused by the turbulence and gustiness of the wind field over the roof and in the wake of a building, a 3-D probabilistic trajectory model of flat-type wind-borne debris is developed in this study. The core of this methodology is a 6 degree-of-freedom deterministic model, derived from the governing equations of motion of the debris, and a Monte Carlo simulation engine used to account for the uncertainty resulting from vertical and lateral gust wind velocity components. The influence of several parameters, including initial wind speed, time step, gust sampling frequency, number of Monte Carlo simulations, and the extreme gust factor, on the accuracy of the proposed model is examined. For the purpose of validation and calibration, the simulated results from the 3-D probabilistic trajectory model are compared against the available wind tunnel test data. Results show that the maximum relative error between the simulated and wind tunnel test results of the average longitudinal position is about 20%, implying that the probabilistic model provides a reliable and effective means to predict the 3-D flight of the plate-type wind-borne debris.