• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.323-329
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• 2009

In this paper, we propose the improvement method of the camera images regardless of exposure environments. By using a double-exposure method, we could improve camera images with clear recognition. We applied the improvement method on the mobile phone. For the feasibility of the proposed algorithm, we compared simulated camera images with the proposed method to conventional images by using auto-exposure image. Experimental results are also shown in this paper.

• Journal of Environmental Health Sciences
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• v.49 no.4
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• pp.210-217
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• 2023

Background: N-nitrosamines are carcinogenic substances often found in rubber products. They are produced when certain additives of rubber products react with nitrite in saliva or air. Exposure assessment for the proper management and communication of N-nitrosamines in rubber balloons should be carried out. Objectives: This study was conducted to determine the concentrations of N-nitrosamines in rubber balloons in the South Korean market and assess exposure among Korean children. Methods: Forty eight rubber balloon products in the domestic market were purchased and a total of 68 balloons were analyzed for N-nitrosamines and N-nitrosatable substances. Chemical analysis was conducted by HPLC-MS/MS according to the method EN 71-12. For exposure assessment, an exposure algorithm and coefficients were obtained from previous studies. Results: Among the 68 rubber balloons, N-nitrosamines were detected in 18 (26.5%) with an average level of 60.77 ㎍/kg. N-Nitrosatable substances were detected in 44 products (64.7%) with an average level of 1353.33 ㎍/kg. As a result of the exposure evaluation, the exposure dose differed according to how exposure coefficients were applied. The median exposure (50th percentile) was higher in the age group of 6~12 years, and high exposure (95th percentile) was higher in the age group of 13~18. Conclusions: We evaluated the N-nitrosamines contained in rubber balloons purchased in the domestic market and assessed oral exposure among South Korean children. For integrated risk management of N-nitrosamines, further studies and discussion regarding exposure and risk assessment are required.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.257-264
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• 2007

In order to obtain a fine picture, a camera has many convenient functions. Its representative functions are Auto Focus(AF), Auto White Balance(AWB) and Auto Exposure(AE). In this paper, we present the new algorithm of Auto Exposure control system, one of its useful functions The proposed algorithm of Auto Exposure control system is based on IIR Filter with Variable Time Constant. First, in order to establish the standards of exposure control, we compare change of the picture luminance with luminance of an object in the Zone system. Second, we make an ideal characteristic graph of luminance by using the results. Finally, we can find the value of the right exposure by comparing an ideal characteristic graph of the luminance with the value of the current expose of a scene. We can find an appropriate exposure as comparing the ideal characteristic graph of the luminance with current exposure of a scene. In order to find a suitable exposure state, we make use of IIR Filter instead of a conventional method using micro-controller. In this paper, the proposed system has therefore simple structure, we use it for compact image sensor module used in the handheld device.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.208-218
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• 2014

Objectives: The major objective of this study was to develop and validate a tier 1 exposure model utilizing worker exposure monitoring data and characteristics of worker activities routinely performed at construction sites, in order to estimate worker exposures without sampling. Methods: The Registration, Evaluation, Authorization and Restriction of Chemicals(REACH) system of the European Union(EU) allows the usage of exposure models for anticipating chemical exposure of manufacturing workers and consumers. Several exposure models have been developed such as Advanced REACH Tools(ART). The ART model is based on structured subjective assessment model. Using the same framework, a tier 1 exposure model has been developed. Worker activities at construction sites have been analyzed and modifying factors have been assigned for each activity. Korean Occupational Safety and Health Agency(KOSHA) accrued work exposure monitoring data for the last 10 years, which were retrieved and converted into exposure scores. A separate set of sampling data were collected to validate the developed exposure model. These algorithm have been realized on Excel spreadsheet for convenience and easy access. Results: The correlation coefficient of the developed model between exposure scores and monitoring data was 0.36, which is smaller than those of EU models(0.6~0.7). One of the main reasons explaining the discrepancy is poor description on worker activities in KOSHA database. Conclusions: The developed tier 1 exposure model can help industrial hygienists judge whether or not air sampling is required or not.

• Journal of the Ergonomics Society of Korea
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• v.24 no.2
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• pp.71-77
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• 2005

In spite of the importance of nuclear power as one of major electric energies in Korea, the nuclear safety has become the most serious social issue in the operation of the nuclear power plant. In this paper, a virtual work simulation program was developed to predict exposure dose during radiation work in radwaste storage. The work simulation program was developed. using $Java ^{TM}$applet and VRML-virtual reality modeling language. A numerical algorithm to find the optimal work path which minimize exposure dose during the given work, was developed and exposure dose on the optimal work path was compared with that on the shortest path. Comparing with the shortest path for the given work, the predicted optimal path consumed longer work time by II% but reduced total exposure dose by 46%. The simulation result showed that the exposure dose depended on not only work time, but also the distance between the worker and the radiation source. The developed simulation program could be a useful tool for the planning of radioactive waste work to increase the radiation safety of workers.

• Journal of Radiation Protection and Research
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• v.36 no.3
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• pp.154-159
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• 2011

To evaluate the radiation exposure of workers participating in task where high radiation exposure is expected, two-dosimeter is typically provided radiation workers, one on the chest and the other on the back, at Korean nuclear power plants (NPPs). In a previous study, the NCRP (55:50) algorithm was selected as the optimal two-dosimeter algorithm (TDA) with various field tests and this TDA has been applied to all Korean NPPs since 2006. In 2007, the International Commission on Radiological Protection (ICRP) published the new ICRP recommendation, ICRP 103, which provides the revised weighting factors for both radiation and tissues and the new reference phantom. In this study, the applicability of current NCRP (55:50) algorithm at Korean NPPs for ICRP 103 was analyzed. As a result, it was found that the NCRP (55:50) algorithm is still effective to estimate the effective dose of workers under ICRP 103.

• Journal of Internet of Things and Convergence
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• v.10 no.3
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• pp.25-33
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• 2024

In tomographic image reconstruction, the focus is on developing CT image reconstruction methods that can maintain high image quality while reducing patient radiation exposure. Typically, statistical image reconstruction methods have the ability to generate high-quality and accurate images while significantly reducing patient radiation exposure. However, in cases like CT image reconstruction, which involve multi-dimensional parameter estimation, the degree of the Hessian matrix of the penalty function is very large, making it impossible to calculate. To solve this problem, the author proposed the PEMG-1 algorithm. However, the PEMG-1 algorithm has issues with the convergence speed, which is typical of statistical image reconstruction methods, and increasing the penalty log-likelihood. In this study, we propose a reconstruction algorithm that ensures fast convergence speed and monotonic increase in likelihood. The basic structure of this algorithm involves sequentially updating groups of pixels instead of updating all parameters simultaneously with each iteration.

• Journal of Environmental Health Sciences
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• v.44 no.6
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• pp.556-562
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• 2018

Objectives: This study was conducted to investigate the boron concentrations in 30 slime products and estimate children's dermal exposure to boron. Methods: Thirty slime products from online and offline stores were purchased for boron analysis. The boron content of each slime sample was analyzed using ICP-OES. A nationwide survey was performed to determine use patterns of slimes by a home-visit survey of 10,000 children divided into three age groups: 0-2, 3-6, and 7-12 years. The dermal exposure to boron was calculated using an exposure algorithm for child slime users. Results: The proportion of the child population using slime was 45.8%, and the mean use frequency was $2.5{\pm}3.8$ per week (range: 0.08-35). Mean time spent playing with slime was $19.6{\pm}11.3min$ (range: 1-100). Twenty-five of the thirty slimes contained a boron concentration exceeding the EU limit for toys made with sticky material of 300 mg/kg. Dermal exposure ranged from $0.0008-13.78{\mu}g/kg/day$ with the maximum weight fractions of boron in the 30 products. The dermal exposure estimate was the highest in 7-12 years old group. Conclusion: Slime use among Korean children may cause high exposure to boron. Regulation is needed to minimize boron exposure from slime products.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.825-836
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• 2019

One of the most challenging safety precautions for workers in dynamic, radioactive environments is avoiding radiation sources and sustaining low exposure. This paper presents a sampling-based algorithm, DL-RRT*, for minimum dose walk-path re-planning in radioactive environments, expedient for occupational workers in nuclear facilities to avoid unnecessary radiation exposure. The method combines the principle of random tree star ($RRT^*$) and $D^*$ Lite, and uses the expansion strength of grid search strategy from $D^*$ Lite to quickly find a high-quality initial path to accelerate convergence rate in $RRT^*$. The algorithm inherits probabilistic completeness and asymptotic optimality from $RRT^*$ to refine the existing paths continually by sampling the search-graph obtained from the grid search process. It can not only be applied to continuous cost spaces, but also make full use of the last planning information to avoid global re-planning, so as to improve the efficiency of path planning in frequently changing environments. The effectiveness and superiority of the proposed method was verified by simulating radiation field under varying obstacles and radioactive environments, and the results were compared with $RRT^*$ algorithm output.

• Journal of Korea Multimedia Society
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• v.25 no.9
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• pp.1273-1283
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• 2022

This paper presents a locally adaptive HDR algorithm using the integral image and MSRCR for LDR images with inadequate exposure. There are two categories in controlling the dynamic range, which are global and local tone mappings. Since the global ones are relatively simple but have some limitations at considering regional characteristics, the local ones are often utilized and MSRCR is a representative method. MSRCR gives moderate results, but it requires lots of computations for multi-scale surround Gaussian functions and produces the Halo effect around the edges. Therefore, in order to resolve these main problems, the proposed algorithm remarkably reduces the computation of the surrounds due to the use of the integral image. And a set of variable-sized windows is adopted to decrease the Halo effect, according to the type of pixel's region. In addition, an offset controlling function is presented, which is mainly affected to the subjective image quality and based on the global input and the desired output means. As the results, the proposed algorithm no more use Gaussian functions and can reduce the computation amount and the Halo effect.