• Journal of Radiation Protection and Research
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• v.47 no.3
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• pp.158-166
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• 2022

Background: The effects of radiation on the health of radiation workers who are constantly susceptible to occupational exposure must be assessed based on an accurate and reliable reconstruction of organ-absorbed doses that can be calculated using personal dosimeter readings measured as H_p(10) and dose conversion coefficients. However, the data used in the dose reconstruction contain significant biases arising from the lack of reality and could result in an inaccurate measure of organ-absorbed doses. Therefore, this study quantified the biases involved in organ dose reconstruction and calculated the bias-corrected H_p(10)-to-organ-absorbed dose coefficients for the use in epidemiological studies of Korean radiation workers. Materials and Methods: Two major biases were considered: (a) the bias in H_p(10) arising from the difference between the dosimeter calibration geometry and the actual exposure geometry, and (b) the bias in air kerma-to-H_p(10) conversion coefficients resulting from geometric differences between the human body and slab phantom. The biases were quantified by implementing personal dosimeters on the slab and human phantoms coupled with a Monte Carlo method and considered to calculate the bias-corrected H_p(10)-to-organ-absorbed dose conversion coefficients. Results and Discussion: The bias in H_p(10) was significant for large incident angles and low energies (e.g., 0.32 for right lateral at 218 keV), whereas the bias in dose coefficients was significant for the posteroanterior (PA) geometry only (e.g., 0.79 at 218 keV). The bias-corrected H_p(10)-to-organ-absorbed dose conversion coefficients derived in this study were up to 3.09- fold greater than those from the International Commission on Radiological Protection publications without considering the biases. Conclusion: The obtained results will aid future studies in assessing the health effects of occupational exposure of Korean radiation workers. The bias-corrected dose coefficients of this study can be used to calculate organ doses for Korean radiation workers based on personal dose records.

• Korean Architects
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• s.655
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• pp.104-105
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• 2023

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.197-202
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• 2004

Recent researches have shown that IKONOS Geo imagery is capable of pixel-level geopositioning accuracy. However, a large number of ground control points(GCPs) are required in this case. For reducing the number of GCPs, users try to use the vender-supplied RPCs with Geo imagery. But, the biases included in RPCs give rise to absolute positioning error of about 25m as well known. In this paper, a method for the compensation of biases in rational polynomial coefficients(RPCs) for IKONOS Geo imagery is developed. the method requires provision of one or two GCPs to generate the compensated RPCs, and the analysis result of practical testing represents two or three pixels accuracy from IKONOS Geo imagery in case of using only compensated RPCs without GCPs.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.642-645
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• 2004

This paper focuses on recovering systematic biases during LIDAR calibration, particularly using natural surfaces as control features. Many previous approaches have utilized all the points overlapping with the control features and often experienced with an inaccurate value converged with a poor rate due to wrong correspondence in pairing a point and the corresponding control features. To overcome these shortcomings, we establish a preventive scheme to select the pairs of high confidence, where the confidence value is based on the error budget associated with the point measurement and the linearity and roughness of the control feature. This approach was then applied to calibraring the LIDAR data simulated with the given systematic biases. The parameters were successfully recovered using the proposed approach with the accuracy and convergence rate superior to those using the previous approaches.

• Journal of The Korean Association For Science Education
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• v.20 no.2
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• pp.193-199
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• 2000

The textbook is a predominant feature of most classrooms. Because the textbook is an important aspect of educational experience, it is essential that the content of the texts be carefully scrutinized. The purpose of this study was to examine the visual portrayal of gender groups in elementary $"Chay{\tilde{o}}n"$ textbooks developed by the 6th National Science Curriculum. An instrument was developed to analyze the nature and type of activity engaged in by these groups as well as how often members of these groups were portrayed. Data were collected from 8 elementary $"Chay{\tilde{o}}n"$ textbooks. The results show the following two different features. While the elementary $"Chay{\tilde{o}}n"$ textbooks do not show gender-biases in representing science learning activities such as observing, experimenting, measuring, they show distinct gender-stereotyped roles and activities. It is expected that the results of this study are considered in developing the new elementary "Science" textbooks which show gender-fairness.

• Asia pacific journal of information systems
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• v.3 no.2
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• pp.55-73
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• 1993

The importance of IS project selection process has been recognized by many IS researchers as well as IS practitioners. The ideal selection process should provide an organization with best IS project from many competing proposals. However, researchers have found that some organizational biases exist in making the selection decisions. This means different selection mechanisms favor projects with different characteristics. The purpose of this study is to reexamine previous findings to determine if the biases still exist in rapidly changing IS environment. An exploratory case study was conducted to gain deeper understanding of the actual IS project selection process. Then scenario approach was used for the empirical study. Some conflicting findings from the previous studies are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.27.4-27.4
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• 2017

(1) The correlation between the mass of supermassive black holes (SMBHs) and the properties of their host galaxies suggests that SMBHs and host galaxies are closely linked in their formation and evolution. While the exact origin of their relationship is still under debate, theoretical models often invoke feedback from active galactic nuclei as a crucial mechanism for establishing the BH-host correlation. In the first part of my talk, I will present possible observational biases in the BH-host relation, and methods to overcome these biases. I will also report our efforts to find observational sign of the AGN feedback in high-z young luminous AGNs. (2) While intermediate-mass black hole (IMBH) is thought be cosmologically important class to understand the link between stellar mass black holes and SMBHs, it is extremely rare in the present-day Universe. In the second part of this talk, I will report a Gemini/GMOS-N IFU study of an ultraluminous X-ray source in NGC 5252, which is a possible candidate of an off-nuclear non-stellar black hole.

• Journal of Aerospace System Engineering
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• v.4 no.1
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• pp.19-22
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• 2010

The accuracy and integrity of global navigation satellite systems (GNSS) can be improved by using GNSS augmentation systems. Large ionospheric spatial gradient, during ionosphere storm, is a major threat for using GNSS augmentation systems by increasing the spatial decorrelation between a reference system and users. Ionosphere decorrelation behavior can be analyzed by using dual frequency GPS data. GNSS receivers have their own biases, called inter-frequency bias (IFB) between dual(P1 and P2) frequencies and they must be accurately estimated before computing ionosphere delays. GPS network data in Korea is used to compute each receiver's IFB, and their estimation accuracy and variability are analyzed. IFB estimation methodology to apply for ionosphere gradient analysis is discussed.

• Phonetics and Speech Sciences
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• v.7 no.3
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• pp.55-64
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• 2015

Previous research on syntactic processing shows that the interpretation of a syntactically ambiguous sentence is frequently strongly biased towards one meaning over another. The current study investigated the effect of bias strength on the production of disambiguating prosody for English ambiguous sentences. In Experiment 1, 40 speakers gave default readings of 18 syntactically ambiguous sentences. Questioning was used to prove intended meanings behind default readings. Intended meanings were treated as interpretation biases when a majority of speakers read a sentence with the same intended meaning. The size of the majority was used to establish bias strength. In Experiment 2, 10 speakers were instructed to use prosody to disambiguate given alternate meanings of the sentences from Experiment 1. The results indicated an effect of bias strength on disambiguating prosody: speakers used temporal juncture cues to reliably disambiguate alternate meanings for sentences with a weak interpretation bias, but not for those with a strong bias. Overall, the results indicated that interpretation biases strongly affect the production of prosody.

• 한국항공운항학회:학술대회논문집
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• 2006.11a
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• pp.71-75
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• 2006