• Journal of Information Processing Systems
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• v.17 no.4
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• pp.737-753
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• 2021

As the demand for high-quality rendering for mixed reality, videogame, and simulation has increased, global illumination has been actively researched. Monte Carlo path tracing can realize global illumination and produce photorealistic scenes that include critical effects such as color bleeding, caustics, multiple light, and shadows. If the sampling rate is insufficient, however, the rendered results have a large amount of noise. The most successful approach to eliminating or reducing Monte Carlo noise uses a feature-based filter. It exploits the scene characteristics such as a position within a world coordinate and a shading normal. In general, the techniques are based on the denoised pixel or sample and are computationally expensive. However, the main challenge for all of them is to find the appropriate weights for every feature while preserving the details of the scene. In this paper, we compare the recent algorithms for removing Monte Carlo noise in terms of their performance and quality. We also describe their advantages and disadvantages. As far as we know, this study is the first in the world to compare the artificial intelligence-based denoising methods for Monte Carlo rendering.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.2
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• pp.110-119
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• 2020

In order to provide priorities of the factors affecting the introduction of Smart Factory, This study reconstructed the factors and calculated the priorities through AHP (Analytic Hierarchy Process). The first layer of the hierarchy have 4 factors; productivity increase, brand image improve, marketing improve, cost reduction. The second layer of the hierarchy have 3 factors belong to the first layer, so the total number of second layer is 12. We divided the characteristics of enterprises into type of manager and age. The C.R. (consistency ratio) values of the respondents were found to be less than 0.1 and were judged to be a 'reasonable test'. As a result, the weights of the higher layer and the lower layer were obtained respectively, and then the weights of the higher layer and the weights of the lower layer were multiplied to obtain the total weights. Unlike previous studies that only surveyed factors that companies consider when introducing smart factory, (1) weighing and prioritizing factors were achieved. There are differences in priorities, (2) smart factory can be studied with the type of manager and firm age. When establishing policies, it is a practical implication (3) to assess its strategy not only for government officials but also for executives.

• Journal of Preventive Medicine and Public Health
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• v.36 no.2
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• pp.163-170
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• 2003

Objectives : This study aimed to develop an evaluation protocol of disability weights using person trade-off, and to test the reliability of the developed protocol in a Korean context. Methods : To develop the valuation protocol, the Global Burden of Disease(GBD) and the Dutch studies were replicated and modified. Sixteen indicator conditions were selected from the Korean version of disease classification, which was based on that of the GBD Study, and the person trade-off method referred to the Dutch method. Results : The disability weights were valued in a two step panel sfudy. The first step was a carefully designed group process by three panels, using person trade-off to establish the disability weights for sixteen selected indicator conditions. The second step consisted of interpolation of the remaining diseases, on a disability scale, by the individual members of three panels. The members of three panels were all medical doctors, with sufficient knowledge of the consequences of a broad variety of diseases. The internal consistency of the Korean disability weights was satisfactory. Considerable agreement existed within each panel and among the panels. Conclusions : It was feasible to use a modified evaluation protocol from those used in GBD and Dutch studies, This would provide a rational basis for an international comparative study of disability weights.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.3
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• pp.79-89
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• 1998

The Error Back-Propagation(EBP) algorithm is widely applied to train a multi-layer perceptron, which is a neural network model frequently used to solve complex problems such as pattern recognition, adaptive control, and global optimization. However, the EBP is basically a gradient descent method, which may get stuck in a local minimum, leading to failure in finding the globally optimal solution. Moreover, a multi-layer perceptron suffers from locking a systematic determination of the network structure appropriate for a given problem. It is usually the case to determine the number of hidden nodes by trial and error. In this paper, we propose a new algorithm to efficiently train a multi-layer perceptron. OUr algorithm uses stochastic perturbation in the weight space to effectively escape from local minima in multi-layer perceptron learning. Stochastic perturbation probabilistically re-initializes weights associated with hidden nodes to escape a local minimum if the probabilistically re-initializes weights associated with hidden nodes to escape a local minimum if the EGP learning gets stuck to it. Addition of new hidden nodes also can be viewed asa special case of stochastic perturbation. Using stochastic perturbation we can solve the local minima problem and the network structure design in a unified way. The results of our experiments with several benchmark test problems including theparity problem, the two-spirals problem, andthe credit-screening data show that our algorithm is very efficient.

• Journal of Korea Trade
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• v.23 no.4
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• pp.1-16
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• 2019

Purpose - This research empirically proves that global shipbuilding industry leadership has moved to China from Korea. Design/Methodology - Competitiveness is measured by AHP for the weights of comprehensive competitiveness, which is the output mixture of three attributive factors: shipbuilding technology, shipbuilding contract price, and export credit. Findings - China is far ahead of Korea for standard vessels such as bulkers and containerships with competitiveness weights of 0.762 and 0.612, respectively, against 0.238 and 0.388 of Korea. Korea is maintaining its competitiveness only in LNG carriers (174k CBM) with a competitiveness weight 0.621. China and Korea have similar competitiveness for chemical carriers, complex vessels with a small hull size. The sources of Chinese competitiveness are shipbuilding contract price and export credit. With the majority share of standard vessel types in the world fleet, China will hold a bigger market share than Korea in the global shipbuilding industry in the forthcoming years. Implications - The swing factors of market power are shipbuilding technology and contract price. If China fails to further develop shipbuilding technology for shipowners worried about the reliability of the Chinese-built vessels, shipowners may swing back to Korea. The rising Chinese labor cost will expedite this swing in the forthcoming competition. Originality/value - To the best of the author's knowledge, this is the first paper that quantitatively examines the competitiveness of shipbuilding between China and Korea by comparing attributive factors for competitiveness.

• Journal of Korean Society of Rural Planning
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• v.28 no.1
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• pp.27-35
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• 2022

This study aims to establish the indicator system of the quality of life of rural residents and to estimate the weights among criteria or sub-criteria that constitute the indicator system of the quality of life using AHP(Analytic Hierarchy Process) method. Indicator system consists of four criteria, that is, health care, eduction & culture, living environment, and income and jobs. Each criterion include three sub-criteria that make up corresponding criterion. The results show that income and jobs was most highly evaluated among the four criteria. It was followed by health care, living environment, and eduction & culture. Among the total 12 sub-criteria, annual income was most highly evaluated, followed by medical service level, job satisfaction, and public transportation environment in terms of global weight which was deduced from expert questionnaire survey. This study implies that rural development policy needs to focus on increasing rural residents' income by creating good quality occupations and increasing the level of medical services, and expanding public transportation services in rural areas. This study has failed to collect local residents' opinions regarding their quality of life in spite of the efforts to reflect the opinions from various expert groups, which is the limitation of this study.

• Journal of Preventive Medicine and Public Health
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• v.37 no.1
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• pp.59-71
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• 2004

Objectives: This study aimed to measure the disability weights for the Korean Burden of Disease study, and to compare them with those adopted in the Australian study to examine the validity and describe the distinctive features. Methods : The standardized valuation protocol was developed from the Global Burden of Disease (GBD) study and the Dutch Disability Weights study. Disability weights were measured for 123 diseases of the Korean version of Disease Classification by three panels of 10 medical doctors each. Then, overall distribution, correlation coefficients, difference by each disease, and mean of differences by disease group were analyzed for comparison of disability weights between the Korean and Australian studies. Results : Korean disability weights ranged from 0.037 to 0.927. While the rank correlation coefficient was moderate to high ($r_s$=0.68), Korean disability weights were higher than the corresponding Australian ones in 79.7% of the 118 diseases. Of these, war, leprosy, and most injuries showed the biggest differences. On the contrary, many infectious and parasitic diseases comprised the greater part of diseases of which Korean disability weights were lower. The mean of the differ ences was the highest in injuries of GBD disease groups, and in cardiovascular disease, injuries, and malignant neoplasm of the Korean disease category. Conclusions : Korean disability weights were found to be valid on the basis of overall distribution pattern and correlation, and are expected to be used as basic data for broadening the scope of burden of disease study. However, some distinctive features still remain to be explored in following studies.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.180-180
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• 2023

To improve global risk management, understanding the characteristics and distribution of precipitation is crucial. However, obtaining spatially and temporally resolved climatic data remains challenging due to sparse gauge observations and limited data availability, despite the use of satellite and reanalysis products. To address this challenge, merging available precipitation products has been introduced to generate spatially and temporally reliable data by taking advantage of the strength of the individual products. However, most of the existing studies utilize all the available products without considering the varying performances of each dataset in different regions. Comprehensively considering the relative contributions of each parent dataset is necessary since their contributions may vary significantly and utilizing all the available datasets for data merging may lead to significant data redundancy issues. Hence, for this study, we introduce a site-specific precipitation merging method that utilizes the Quadruple Collocation (QC) approach, which acknowledges the existence of error-cross correlation between the parent datasets, to create a high-resolution global daily precipitation data from 2001-2020. The performance of multiple gridded precipitation products are first evaluated per region to determine the best combination of quadruplets to be utilized in estimating the error variances through the QC approach and computation of merging weights. The merged precipitation is then computed by adding the precipitation from each dataset in the quadruplet multiplied by each respective merging weight. Our results show that our approach holds promise for generating reliable global precipitation data for data-scarce regions lacking spatially and temporally resolved precipitation data.

• Health Policy and Management
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• v.26 no.4
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• pp.352-358
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• 2016

Summary measures of population health (SMPHs) have been used to estimate the burden of diseases. Among various type of SMPHs, disability adjusted life year (DALY) and healthy life expectancy (HALE) have been calculated in the global and national burden of disease studies. In order to calculate DALY and HALE, disability weight is an essential element. Disability weights quantify the level of disability for health states or diseases and have values between 0 (full health) to 1 (being dead). In this study, we reviewed the main disability weights studies and determined their meaning and limitations. Furthermore, we provided the whole process of typical disability weight study and reviewed key issues as follows: health state or disease description development, panel composition, valuation method, validation of disability weight, cross-cultural variability in health state or disease, and so on. The results from this study will be helpful to conduct future disability weight studies for adapting disability weights and developing new methodologies.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.367-370
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• 2006

Performances of multiple surrogate models are evaluated in a turbomachinery blade shape optimization. The basic models, i.e., Response Surface Approximation, Kriging and Radial Basis Neural Network models as well as weighted average models are tested for shape optimization. Global data based errors for each surrogates are used to calculate the weights. These weights are multiplied with the respective surrogates to get the final weighted average models. The design points are selected using three level fractional factorial D-optimal designs. The present approach can help address the multi-objective design on a rational basis with quantifiable cost-benefit analysis.