• Title/Summary/Keyword: Uncertainty

Search Result 6,989, Processing Time 0.038 seconds

Evaluation of MODIS-derived Evapotranspiration at the Flux Tower Sites in East Asia (동아시아 지역의 플럭스 타워 관측지에 대한 MODIS 위성영상 기반의 증발산 평가)

  • Jeong, Seung-Taek;Jang, Keun-Chang;Kang, Sin-Kyu;Kim, Joon;Kondo, Hiroaki;Gamo, Minoru;Asanuma, Jun;Saigusa, Nobuko;Wang, Shaoqiang;Han, Shijie
    • Korean Journal of Agricultural and Forest Meteorology
    • /
    • v.11 no.4
    • /
    • pp.174-184
    • /
    • 2009
  • Evapotranspiration (ET) is one of the major hydrologic processes in terrestrial ecosystems. A reliable estimation of spatially representavtive ET is necessary for deriving regional water budget, primary productivity of vegetation, and feedbacks of land surface to regional climate. Moderate resolution imaging spectroradiometer (MODIS) provides an opportunity to monitor ET for wide area at daily time scale. In this study, we applied a MODIS-based ET algorithm and tested its reliability for nine flux tower sites in East Asia. This is a stand-alone MODIS algorithm based on the Penman-Monteith equation and uses input data derived from MODIS. Instantaneous ET was estimated and scaled up to daily ET. For six flux sites, the MODIS-derived instantaneous ET showed a good agreement with the measured data ($r^2=0.38$ to 0.73, ME = -44 to $+31W\;m^{-2}$, RMSE =48 to $111W\;m^{-2}$). However, for the other three sites, a poor agreement was observed. The predictability of MODIS ET was improved when the up-scaled daily ET was used ($r^2\;=\;0.48$ to 0.89, ME = -0.7 to $-0.6\;mm\;day^{-1}$, $RMSE=\;0.5{\sim}1.1\;mm\;day^{-1}$). Errors in the canopy conductance were identified as a primary factor of uncertainty in MODIS-derived ET and hence, a more reliable estimation of canopy conductance is necessary to increase the accuracy of MODIS ET.

Assessing hydrologic impact of climate change in Jeju Island using multiple GCMs and watershed modeling (다중 GCM과 유역모델링을 이용한 기후변화에 따른 제주도의 수문학적 영향 평가)

  • Kim, Chul Gyum;Cho, Jaepil;Kim, Nam Won
    • Journal of Korea Water Resources Association
    • /
    • v.51 no.1
    • /
    • pp.11-18
    • /
    • 2018
  • The climate change impacts on hydrological components and water balance in Jeju Island were evaluated using multiple climate models and watershed model, SWAT-K. To take into account the uncertainty of the future forecast data according to climate models, climate data of 9 GCMs were utilized as weather data of SWAT-K for future period (2010-2099). Using the modeling results of the past (1992-2013) and the future period, the hydrological changes of each year were analyzed and the precipitation, runoff, evapotranspiration and recharge were increasing. Compared with the past, the change in the runoff was the largest (up to 50% increase) and the evapotranspiration was relatively small (up to 11% increase). Monthly results show that the amount of evapotranspiration and the amount of recharge are greatly increased as the amount of precipitation increases in August and September, while the amount of evapotranspiration decreases in the same period. January and December showed the opposite tendency. As a result of analyzing future water balance changes, the ratio of runoff, evapotranspiration, and recharge to rainfall did not change much, but compared to the past, the runoff rate increased up to 4.3% in the RCP 8.5 scenario, while the evapotranspiration rate decreased by up to 3.5%. Based on the results of other researchers and this study, it is expected that rainfall and runoff will increase gradually in the future under the assumption of present climate change scenarios. Especially summer precipitation and runoff are expected to increase. As a result, the amount of groundwater recharge in Jeju Island will increase.

Technology Innovation Activity and Default Risk (기술혁신활동이 부도위험에 미치는 영향 : 한국 유가증권시장 및 코스닥시장 상장기업을 중심으로)

  • Kim, Jin-Su
    • Journal of Technology Innovation
    • /
    • v.17 no.2
    • /
    • pp.55-80
    • /
    • 2009
  • Technology innovation activity plays a pivotal role in constructing the entrance barrier for other firms and making process improvement and new product. and these activities give a profit increase and growth to firms. Thus, technology innovation activity can reduce the default risk of firms. However, technology innovation activity can also increase the firm's default risk because technology innovation activity requires too much investment of the firm's resources and has the uncertainty on success. The purpose of this study is to examine the effect of technology innovation activity on the default risk of firms. This study's sample consists of manufacturing firms listed on the Korea Securities Market and The Kosdaq Market from January 1,2000 to December 31, 2008. This study makes use of R&D intensity as an proxy variable of technology innovation activity. The default probability which proxies the default risk of firms is measured by the Merton's(l974) debt pricing model. The main empirical results are as follows. First, from the empirical results, it is found that technology innovation activity has a negative and significant effect on the default risk of firms independent of the Korea Securities Market and Kosdaq Market. In other words, technology innovation activity reduces the default risk of firms. Second, technology innovation activity reduces the default risk of firms independent of firm size, firm age, and credit score. Third, the results of robust analysis also show that technology innovation activity is the important factor which decreases the default risk of firms. These results imply that a manager must show continuous interest and investment in technology innovation activity of one's firm. And a policymaker also need design an economic policy to promote the technology innovation activity of firms.

  • PDF

Development of Devices for Improving the Reducibility of Patient Positioning on a Breast Board (Breast Board를 이용한 방사선치료에서 환자 위치 재현성 향상 방안에 대한 연구)

  • Huh Soon Nyung;Cho Woong;Park Yang Kyun;Ha Sung Whan
    • Radiation Oncology Journal
    • /
    • v.23 no.2
    • /
    • pp.123-130
    • /
    • 2005
  • Purpose: We wanted to improve the setup reproducibility of breast cancer patients when utilizing a commercially available breast board for radiation therapy. The breast board was modified by using a new head rest and 2 types of board fixation devices. Materials and Methods: A conventional head/neck rest was modified to be positioned in various slots of the breast board, and it was fabricated 1 cm thinner to provide more comfort to a patient when the patient's neck was rotated. This rest improves the uncertainty of the daily setup. Also, the sagging problems at the left and right sides became negligible with the two types of board fixation devices: (1) the stair type, and (2) the arm type. The first device consists of an upper/lower holder with 4 stair-types of grooves and 4 rectangular Inserts. In order to cover the whole range of vertical setup of the breast board, 4 rectangular inserts were needed, and each covered 10 steps. The arm-type fixation device was also fabricated and attached to the breast board, It had two aluminum bars that were fixed by utilizing a lock-type of screw. These devises were evaluated with two volunteers in order to prove the effectiveness of the improved setup accuracy. Results; The developed cranio-caudal fixation device demonstrated that it could reduce the cranio-caudal error by nearly $55\%$ compared to the old device. As for left-and-right inclination, the stair-type and arm-type fixation devices can reduce the relative inclination by nearly $80\%$ and $90\%$, respectively, compared to the breast board without the fixation device. Conclusion: It was verified that the developed devices were effective for positioning the patients and for avoiding inclination of the breast board.

The Non-Destructive Determination of Heavy Metals in Welding Fume by EDXRF (EDXRF에 의한 용접흄 중의 중금속의 비파괴 정량)

  • Park, Seunghyun;Jeong, Jee Yeon;Ryoo, Jang Jin;Lee, Naroo;Yu, Il Je;Song, Kyung Seuk;Lee, Yong Hag;Han, Jeong Hee;Kim, Sung Jin;Park, Jung sun;Chung, Ho Keun
    • Journal of Korean Society of Occupational and Environmental Hygiene
    • /
    • v.11 no.3
    • /
    • pp.229-234
    • /
    • 2001
  • The EDXRF(Energy Dispersive X-ray Fluorescence Spectrometer) technique was applied to the determination of heavy metals in welding fume. The EDXRF method designed in this study was a non-destructive analysis method. Samples were analyzed directly by EDXRF without any pre-treatment such as digestion and dilution. The samples used to evaluate this method were laboratory samples exposed in a chamber connected with a welding fume generator. The samples were first analyzed using a non-destructive EDXRF method. The samples subsequently were analyzed using AAS method to verify accuray of the EDXRF method. The purpose of this study was to evaluate the possibility of the non-destructive analysis of heavy metals in welding fume by EDXRF. The results of this study were as follow: 1.When the samples were collected under the open-face sampling condition, a surface distribution of welding fume particles on sample filters was uniform, which made non-destructive analysis possible. 2. The method was statistically evaluated according to the NIOSH(National Institute for Occupational Safety and Health) and HSE(Health and Safety Executive) method. 3. The overall precision of the EDXRF method Was calculated at 3.45 % for Cr, 2.57 % for Fe and 3.78 % for Mn as relative standard deviation(RSD), respectively. The limits of detection were calculated at $0.46{\mu}g$/sample for Cr, $0.20{\mu}g$/sample for Fe and $1.14{\mu}g$/sample for Mn, respectively. 4. A comparison between the results of Cr, Fe, Mn analyzed by EDXRF and AAS was made in order to assess the accuracy of EDXRF method. The correlation coefficient between the results of EDXRF and AAS was 0.9985 for Cr, 0.9995 for Fe and 0.9982 for Mn, respectively. The overall uncertainty was determined to be ${\pm}12.31%$, 8.64 % and 11.91 % for Cr, Fe and Mn, respectively. In conclusion, this study showed that Cr, Fe, Mn in welding fume were successfully analyzed by the EDXRF without any sample pre-treatment such as digestion and dilution and a good correlation between the results of EDXRF and AAS was obtained. It was thus possible to use the EDXRF technique as an analysis method of working environment samples. The EDXRF method was an efficient method in a non-destructive analysis of heavy metals in welding fume.

  • PDF

The Naturally Occurring Levels of Nitrate and Nitrite in Livestock Products (축산물 중 천연유래 질산염 및 아질산염 함유량 조사)

  • Choi, Jae-Chun;Park, So-Ra;Lim, Ho-Soo;Ko, Kyung-Yuk;Kim, Meehye
    • Journal of Food Hygiene and Safety
    • /
    • v.30 no.3
    • /
    • pp.265-271
    • /
    • 2015
  • This study was done in order to investigate the naturally occurring levels of nitrate and nitrite in livestock products. Total samples of 458 consisting of meats (n = 223), processed meat products (n = 51), raw milks (n = 30), processed milk products (n = 142), eggs (n = 5) and processed egg products (n = 7) were analyzed for contents of nitrate and nitrite by ion chromatography (IC). That methods showed good results in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ), recovery, reproducibility and uncertainty. Nitrate and nitrite were detected in 167 and 40 samples, respectively. The nitrate levels (mg/kg) were not detected (ND)~40.23 for modified milks, ND~37.97 for sauce meats, ND~32.40 for process cheeses, ND~31.50 for processed egg products, ND~27.73 for dry milks, ND~24.76 for sausages, ND~22.45 for bacons, ND~21.55 for natural cheeses, ND~20.82 for hams and fermented milks, ND~13.57 for eggs, ND~12.77 for butters, ND~9.31 for milks and ND~3.88 for meats while the nitrite levels (mg/kg) were ND~17.35 for processed egg products and ND~1.92 for meats. In conclusion, the result of this study of nitrate and nitrite in livestock products could be used as one of scientific base datum to determine whether they are naturally occurring or not, including ingredients and their percentage, manufacturing processes, other papers relating to naturally occurring levels of them, and so on.

A study on the moral instruction as a poetic act (시적 행위로서의 도덕과 수업)

  • Song, Young-min
    • The Journal of Korean Philosophical History
    • /
    • no.31
    • /
    • pp.87-111
    • /
    • 2011
  • In moral instruction, one of the important purposes is cultivate students' meaningful moral knowing. To obtain this purpose, generally systems approach has been adopted and used in moral instruction. Systems approach has emphasized efficient designs which do not occur incidental learning that does not contribute to obtain learning objectives. However, moral meaning may occur to the subject of knowing, then occurrence of coincidence can not be excluded. If we approach to moral instruction with operative and engineering ways, we may convey the learning object but it won't be received meaningfully. Because of such problem, moral instruction has been required an alternative perspective contrary to the systems approach. Above all we need to reconsider the logic of explanation based on the systems approach. Because the moral instruction is understood that it is a systematic and operative act according to the logic of explanation. According to the logic of explanation, education is an act that conveys the teachers' knowledge to students who have inferior knowledge to teachers'. During this process, students' interpretation has been overlooked. In moral instruction, the teachers' interpretation of moral meaning can occur and extend by students' interpretation. When we understand moral instruction as the course of alliance between interpretation, it could be stood out that teaching as a symbol, constitution of teaching text as a vacuum, learning as a coincidence. When we stand out these aspects, the moral instruction could be understand as a poetic act. And based on such understanding, we can abstract specific resemblances between the poetic act and the moral instruction. There are semantic invariants and semantic variants in the teaching text of moral instruction. The semantic variants premise uncertainty. The limitation, that is, semantic invariants and the openness which is possible within semantic variants are changed to the moral instruction by students' response. It is essential that a selective attention as esthetic transaction that could be changed from text to poet. Like this, we need to take notice of instructive aspects not to means for reaching learning objectives but to act for being possible disinterested experiential learning.

Improvement of Personal Information Protection Laws in the era of the 4th industrial revolution (4차 산업혁명 시대의 개인정보보호법제 개선방안)

  • Choi, Kyoung-jin
    • Journal of Legislation Research
    • /
    • no.53
    • /
    • pp.177-211
    • /
    • 2017
  • In the course of the emergence and development of new ICT technologies and services such as Big Data, Internet of Things and Artificial Intelligence, the future will change by these new innovations in the Fourth Industrial Revolution. The future of this fourth industrial revolution will change and our future will be data-based society or economy. Since there is personal information at the center of it, the development of the economy through the utilization of personal information will depend on how to make the personal information protection laws. In Korea, which is trying to lead the 4th industrial revolution, it is a legal interest that can not give up the use of personal information, and also it is an important legal benefit that can not give up the personal interests of individuals who want to protect from personal information. Therefore, it is necessary to change the law on personal information protection in a rational way to harmonize the two. In this regard, this article discusses the problems of duplication and incompatibility of the personal information protection law, the scope of application of the personal information protection law and the uncertainty of the judgment standard, the lack of flexibility responding to the demand for the use of reasonable personal information, And there is a problem of reverse discrimination against domestic area compared to the regulated blind spot in foreign countries. In order to solve these problems and to improve the legislation of personal information protection in the era of the fourth industrial revolution, we proposed to consider both personal information protection and safe use by improving the purpose and regulation direction of the personal information protection law. The balance and harmony between the systematical maintenance of the personal information protection legislation and laws and regulations were also set as important directions. It is pointed out that the establishment of rational judgment criteria and the legislative review to clarify it are necessary for the constantly controversial personal information definition regulation and the method of allowing anonymization information as the intermediate domain. In addition to the legislative review for the legitimate and non-invasive use of personal information, there is a need to improve the collective consent system for collecting personal information to differentiate the subject and to improve the legislation to ensure the effectiveness of the regulation on the movement of personal information between countries. In addition to the issues discussed in this article, there may be a number of challenges, but overall, the protection and use of personal information should be harmonized while maintaining the direction indicated above.

Modified Traditional Calibration Method of CRNP for Improving Soil Moisture Estimation (산악지형에서의 CRNP를 이용한 토양 수분 측정 개선을 위한 새로운 중성자 강도 교정 방법 검증 및 평가)

  • Cho, Seongkeun;Nguyen, Hoang Hai;Jeong, Jaehwan;Oh, Seungcheol;Choi, Minha
    • Korean Journal of Remote Sensing
    • /
    • v.35 no.5_1
    • /
    • pp.665-679
    • /
    • 2019
  • Mesoscale soil moisture measurement from the promising Cosmic-Ray Neutron Probe (CRNP) is expected to bridge the gap between large scale microwave remote sensing and point-based in-situ soil moisture observations. Traditional calibration based on $N_0$ method is used to convert neutron intensity measured at the CRNP to field scale soil moisture. However, the static calibration parameter $N_0$ used in traditional technique is insufficient to quantify long term soil moisture variation and easily influenced by different time-variant factors, contributing to the high uncertainties in CRNP soil moisture product. Consequently, in this study, we proposed a modified traditional calibration method, so-called Dynamic-$N_0$ method, which take into account the temporal variation of $N_0$ to improve the CRNP based soil moisture estimation. In particular, a nonlinear regression method has been developed to directly estimate the time series of $N_0$ data from the corrected neutron intensity. The $N_0$ time series were then reapplied to generate the soil moisture. We evaluated the performance of Dynamic-$N_0$ method for soil moisture estimation compared with the traditional one by using a weighted in-situ soil moisture product. The results indicated that Dynamic-$N_0$ method outperformed the traditional calibration technique, where correlation coefficient increased from 0.70 to 0.72 and RMSE and bias reduced from 0.036 to 0.026 and -0.006 to $-0.001m^3m^{-3}$. Superior performance of the Dynamic-$N_0$ calibration method revealed that the temporal variability of $N_0$ was caused by hydrogen pools surrounding the CRNP. Although several uncertainty sources contributed to the variation of $N_0$ were not fully identified, this proposed calibration method gave a new insight to improve field scale soil moisture estimation from the CRNP.

A Study on the Influence of the Founder's Self-Efficacy on the Sales of the Founding Company (창업자의 자기효능감이 창업기업의 매출에 미치는 영향에 관한 연구)

  • Lee, Joonsung;Song, Inam
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
    • /
    • v.14 no.5
    • /
    • pp.61-78
    • /
    • 2019
  • This study is about the effect of the founder's self-efficacy on the sales of the founding company by focusing on the factors that are currently emphasized in the founding education. In particular, this paper starts from the consciousness of the problem that the education that is being implemented to achieve the purpose of successful start-up among various government-based start-up support projects is failing to produce many start-up failures. Entrepreneurs cannot be assessed by objective financial data, but there is a high degree of uncertainty that should be determined based on their personal and learning abilities. In addition, many previous studies, which are likely to be successful when there is a high self-efficacy in a specific field due to the influence of factors such as personal experience or learning, will answer the direction of support for start-up companies. This study focuses on the impact of the founder's self-efficacy on the sales of the founding firms, especially the sales that are the key to the survival of the founding firms. This study has six major studies. First, to analyze whether the self-efficacy of entrepreneurs with respect to entrepreneurship affects the sales of entrepreneurs. Second, to analyze whether the self-efficacy of entrepreneurs with respect to market orientation affects the sales of entrepreneurs. Analysis of whether the founder's self-efficacy affects the sales of the founding firms. Fourth, analysis of whether the founder's self-efficiency affects the sales of the founding firms' understanding of management environment changes. An analysis of whether efficacy affects the sales of a start-up company, and sixth, an analysis of whether the founder's self-efficacy of business model building ability affects the sales of a start-up company. As a result of the empirical analysis, this study found that the self-efficacy of entrepreneurs on product differentiation capability and business model building capacity had a positive influence on the sales of entrepreneurs. The self-efficacy had a positive effect on self-efficacy, and the customer orientation had a positive effect on self-efficacy on business model building capacity. Also, it was confirmed that a path exists between the components of self-efficacy and that self-efficacy through the path has a positive effect on the sales of the start-up company. Therefore, the results of this study suggest the implications of establishing such a path and strengthening self-efficacy to create the survival and start-up performance of a start-up company if the goal of the start-up company is to survive when implementing various support projects for the start-up company.