• 한국시스템다이내믹스연구
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• 제15권2호
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• pp.97-131
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• 2014

The purpose of this study is to analyze Foreign Exchange(FX) exposure and FX hedge strategy based on the systems thinking perspective using causal loop diagrams. FX exposure has been a critical issue on a business management. Many studies in Korea have researches on variables which make effects to the company value. This study displays causal loop diagrams(CLDs) on these issues. In order to make CLD more objective, most causalities are articulated from recent 72 studies (1998~2013) of domestic top journals. This approach is valuable in that it is the first try to draw all the causalities from various literature review regarding FX exposure and FX hedge strategy. This study is expected to make a useful and basic material to research the financial issues of corporate, as the first research to dynamically understand FX exposure and FX hedge strategy.

• 한국산학기술학회논문지
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• 제4권3호
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• pp.223-229
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• 2003

ICRP-60 신권고에 맞게 수정된 방사선피폭선량 계산프로그램인 K-DOSE 60을 4개 발전소 (고리, 월성, 울진, 영광)에 적용하여 주변주민 최대개인피폭선량을 평가하였다 핵종, 장기, 경로별로 결정변수값들을 도출한 결과, 경로는 성인의 경우 농작물, 유아의 경우 우유가, 핵종은 ³H, /sup 133/Xe, /sup 60/Co (고리 1,2발전소), /sup 14/C, /sup 41/Ar(월성 1,2발전소)로 나타났으며, 모든 장기에 대한 피폭선량차이가 매우 작았다. "출력 대 입력" 변동에 근거한 민감도 분석결과, 핵종의 화학적 형태가 타 입력변수들보다 10² factor만큼 높은 민감도를 보였으며, 전이/농축계수에 의한 민감도는 섭취량이나 방출량의 그것에 비하여 상대적으로 매우 낮았다. PCC를 이용한 상관성 민감도의 경우는 4가지 입력변수 모두 0.97 이상의 높은 상관성을 보였다.

• 한국농공학회논문집
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• 제63권6호
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• pp.141-150
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• 2021

In order to assess the impact of climate change on irrigation reservoirs, climate exposure (EI), sensitivity (SI), and potential impact (PI) were evaluated for 1,651 reservoirs nationwide. Climate exposure and sensitivity by each reservoir were calculated using data collected from 2011 to 2020 for seven proxy variables (e.g. annual rainfall) and six proxy variables (e.g. irrigation days), respectively. The potential impact was calculated as the weighted sum of climate exposure and sensitivity, and was classified into four levels: 'Low (PI<0.4)', 'Medium (PI<0.6)', 'High (PI<0.8)', and 'Critical (PI≥0.8)'. The result showed that both the climate exposure index and the sensitivity index were on average high in Daegu and Gyeongbuk with high temperature and low rainfall. About 79.8% of irrigation reservoirs in Daegu, Gyeongbuk, and Ulsan with high climate exposure and sensitivity resulted in a 'High' level of potential impact. On the contrary, 64.5% of the study reservoirs in Gyeongnam and Gangwon showed 'Low' in potential impact. In further studies, it is required to reorganize the proxy variables and the weights in accordance with practical alternatives for improving adaptive capacity to drought, and it is expected to contribute to establishing a framework for vulnerability assessment of an irrigation reservoir.

• Environmental Engineering Research
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• 제13권2호
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• pp.73-78
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• 2008

For a given soil-contaminated site, a level of soil contamination is characterized and decisions on risk may be made from the risk assessment. The study evaluated critical design factors for the determination of sample size in the sampling design plan and the assessment of soil contaminant- leaching to groundwater. Two variables, the minimum relative detectable difference (T) and coefficient of variation (CV) were evaluated for the sample size determination. The minimum number of samples can be appropriately determined by CV under a T value greater than or equal to 0.2. Soil-contaminant leaching to groundwater was evaluated by using the Soil Screening Level equation of U.S. Environmental Protection Agency and the Risk Based Screening Level equation of American Society for Testing and Materials, with the same input parameters. The groundwater concentrations estimated from soil contaminant concentrations were significantly affected by the Darcy velocity of groundwater and the organic content of soil.

• International Journal of Precision Engineering and Manufacturing
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• 제9권1호
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• pp.12-18
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• 2008

This paper describes two run-to-run controllers, a nonlinear multiple exponential-weight moving-average (NMEWMA) controller and a dynamic model-tuning minimum-variance (DMTMV) controller, for photolithography processes. The relationships between the input recipes (exposure dose and focus) and output variables (critical dimensions) were formed using an experimental design method, and the photolithography process model was built using a multiple regression analysis. Both the NMEWMA and DMTMV controllers could update the process model and obtain the optimal recipes for the next run. Quantified improvements were obtained from simulations and real photolithography processes.

• Imaging Science in Dentistry
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• 제48권2호
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• pp.111-119
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• 2018

Purpose: This study was conducted to evaluate the accuracy of linear measurements of 3-dimensional (3D) images generated by cone-beam computed tomography (CBCT) and facial scanning systems, and to assess the effect of scanning parameters, such as CBCT exposure settings, on image quality. Materials and Methods: CBCT and facial scanning images of an anthropomorphic phantom showing 13 soft-tissue anatomical landmarks were used in the study. The distances between the anatomical landmarks on the phantom were measured to obtain a reference for evaluating the accuracy of the 3D facial soft-tissue images. The distances between the 3D image landmarks were measured using a 3D distance measurement tool. The effect of scanning parameters on CBCT image quality was evaluated by visually comparing images acquired under different exposure conditions, but at a constant threshold. Results: Comparison of the repeated direct phantom and image-based measurements revealed good reproducibility. There were no significant differences between the direct phantom and image-based measurements of the CBCT surface volume-rendered images. Five of the 15 measurements of the 3D facial scans were found to be significantly different from their corresponding direct phantom measurements(P<.05). The quality of the CBCT surface volume-rendered images acquired at a constant threshold varied across different exposure conditions. Conclusion: These results proved that existing 3D imaging techniques were satisfactorily accurate for clinical applications, and that optimizing the variables that affected image quality, such as the exposure parameters, was critical for image acquisition.

• 인지과학
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• 제18권2호
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• pp.113-138
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• 2007

풍경 그림을 사용하여 도식이 기억에 미치는 영향을 알아보았다. 실험 1에서는 즉시 검사를 실시하여 부호화할 때 도식이 기억에 미치는 영향을 알아보았고, 실험 2에서는 3일 지연 검사를 실시하여 파지기간 동안 도식이 기억에 미치는 영향을 알아보았다. 두 실험 모두에서 제시시간(250ms vs 1000ms)을 다르게 하고 목표 미끼를 생략하는 조건과 목표 미끼를 다른 물건으로 대체하는 조건으로 항목의 축어적 정보 부호화를 조작하였다. 특히 생략과 대체 조건을 비교하여 도식에 기반한 기대라는 하향정보 특정항목에 대한 상향정보가 기억에 미치는 효과를 알아보았다. 두 개의 실험에서 전형적인 항목에 대한 오기억은 지연검사에서도 별 변화가 없는데 반해 학습 항목에 대한 기억은 감소하였으며, 오기억은 생략조건에서 더 많이 보고되었으나, 비전형 항목에 대한 기억은 감소하였으며, 오기억은 생략조건에서 더 많이 보고되었으나, 비전형 항목에 대한 기억은 대체조건에서 더 많이 보고되었다. 이 결과는 도식에 기반한 오기억은 비교적 지속적이며, 도식에 의한 기대라는 하향 정보가 상향 정보와 충돌이 일어날 때에는 오기억이 감소한다는 사실을 보여 주었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.1037-1040
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• 2002

In micro-stereolithography technology, fabrication conditions that include laser power, laser scan speed, laser scan pitch, and material property of photopolymer such as penetration depth and critical exposure are considered as major process variables. But the existing scan path generation methods based only on CAD model have not taken them into account, which has resulted in cross-section dimension of low accuracy. Thus, to enhance cross-section dimensional accuracy, the physical resin solidification n phenomena should be reflected in laser scan path generation and stage operating code. In this paper, multi-line experiments based on single line solidification model are performed. And the method for improving cross-section dimensional accuracy is presented, which is to apply the database based on experimental results to laser scan path generation.

• Journal of Preventive Medicine and Public Health
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• 제52권2호
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• pp.92-100
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• 2019

Objectives: Young adulthood represents a critical developmental period during which the use of tobacco may begin or cease. Furthermore, differences in smoking behaviors between younger (aged 18-24 years) and older (aged 25-34 years) young adults may exist. This study aimed to characterize patterns related to current smoking in younger and older young adults. Methods: This study used data acquired from the Sixth Korea National Health and Nutrition Examination Survey conducted from 2013 to 2014. A total of 2069 subjects were categorized as younger (712 subjects) and older (1357 subjects) young adults. The chi-square test was used to assess the relationships between smoking status and socio-demographic, health-related, and smoking-related factors. Multivariable logistic regression models were constructed to assess the factors affecting current smoking in these age groups. Results: The current smoking prevalence was 18.3% among the younger young adults and 26.0% among the older young adults. Sex, education level, occupation, perceived health status, alcohol consumption, and electronic cigarette use were related to current smoking in both age groups. Secondhand smoke exposure at home and stress levels showed significant relationships with smoking in younger and older young adults, respectively. Conclusions: Strong correlations were found between the observed variables and smoking behaviors among young adults. Determining the factors affecting smoking and designing interventions based on these factors are essential for smoking cessation in young adults.

• 복합신소재구조학회 논문집
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• 제5권3호
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• pp.8-16
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• 2014

Torque control method and turn of nut method are specified as clamping method of high strength bolts in the steel construction specifications. Quality control of torque coefficient is essential activity because torque control method, which is presently adopted as clamping method in domestic construction sites, is affected by variation of torque coefficient. The clamping of torque shear bolt is based on KS B 2819. It was misunderstood that the tension force of the TS bolt was induced generally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the intended tension, as it considerably varies due to torque coefficient dependent on the environmental factors and temperature variables despite the break of the pin tail.This study was focused to evaluate the effect of environmental factors and errors of installing bolts during tightening high strength bolts. The environmental parameters were composed of 'wet' condition, 'rust' condition, 'only exposure to air' condition. And the manufacture of trial product was planned to identify the induced force into the bolts. The algorithm for a trial product was composed of the relation between electricity energy taken from torque shear wrench and tension force from hydraulic tension meter.