• Toxicological Research
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• 제17권
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• pp.17-24
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• 2001

Risk assessment is useful tool making good decisions on the risks of certain hazardous com-pound and suggests safe margin through scientific process using toxicological data, statistical tool, exposure value and relevant variants. The goal of risk management is to protect the public health from hazardous compound based on result of risk assessment having reality. For the suggestion of exact man-aging information, risk assessment must be designed to represent a "plausible estimate" of the exposure to the individuals and to minimize uncertainty. Risk assessment methodology and knowledge are expected to change more rapidly than before and up-to-date methodology should be applied in regulatory aspects through the Agency. For the useful application of risk assessment, the communication between the risk assessor and the risk manager is needed before the initiation of the risk assessment and upon its completion. Generally, the risk assessment itself as a practical tool in the regulatory decision making process would be regarded with social economic impact.ic impact.

• Communications for Statistical Applications and Methods
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• 제11권2호
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• pp.413-418
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• 2004

Statistically illiterate people seem to believe that there are some strategies for choosing winning numbers in lottery. One seemingly plausible strategy is to select the hot numbers which most frequently appeared in the past. In this article we investigate the existence of hot numbers in the Korean national lottery called Lotto. A numerical method is proposed to estimate the exact sampling distribution of test statistic for checking the existence of hot numbers among 45 possible numbers of choice.

• ETRI Journal
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• 제38권4호
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• pp.776-786
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• 2016

The fairly recent standard of equipping mobile devices with advanced imaging sensors has opened the possibility of conveniently diagnosing skin conditions, anywhere, anytime. For this application, we attempted to estimate skin conditions from a skin image taken by a mobile handheld camera. To estimate the skin conditions, we specifically identified three skin features (pigmentation, pores, and roughness) that can be measured quantitatively from a skin image. The experimental data indicate that the existing thresholding methods are inappropriate for extracting the pigmentation and pore skin features. Thus, we propose a new line-fitting based thresholding method for skin feature detection. We thoroughly evaluated our proposed skin condition estimation method using our skin image database. The experimental results show that our proposed thresholding method can better determine the threshold leading to the most visually plausible detection, when compared to existing methods. We also confirmed that skin conditions can be feasibly estimated using a common mobile handheld camera (for example, a smartphone).

• 한국컴퓨터그래픽스학회논문지
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• 제17권3호
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• pp.21-31
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• 2011

논문에서는 마커리스 증강현실 가시화에서 반사구(mirror-sphere)를 이용하여 실제 환경의 광원위치를 추정한 결과를 증강되는 가상객체에 적용하는 방법을 제안한다. 고정된 환경조명의 안정적인 추정을 위해, 카메라를 반사구 주위를 돌며 촬영하여 반사구에 대한 다중 영상을 획득한 후, 각 광원 벡터 클러스터의 주광원 방향을 추정한다. 본 논문에서는 환경 조명의 광원방향 추정과 함께 움직이는 광원에 대한 광원방향도 추정함으로써, 실제 조명환경을 증강되는 가상 객체에 반영하여 사실적인 음영효과와 그림자를 생성한다. 본 논문에서 제안하는 조명 추정 방법은 조명 환경에 대한 어떠한 사전 정보 없이도 즉각적으로 증강현실 가시화에 적용할 수 있다.

• Journal of Astronomy and Space Sciences
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• 제38권2호
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• pp.83-92
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• 2021

The ionization degree of hydrogen is crucial in the physics of the plasma in the solar chromosphere. It specifically limits the range of plasma temperatures that can be determined from the Hα line. Given that the chromosphere greatly deviates from the local thermodynamic equilibrium (LTE) condition, precise determinations of hydrogen ionization require the solving of the full set of non-LTE radiative transfer equations throughout the atmosphere, which is usually a formidable task. In many cases, it is still necessary to obtain a quick estimate of hydrogen ionization without having to solve for the non-LTE radiative transfer. Here, we present a simple method to meet this need. We adopt the assumption that the photoionizing radiation field changes little over time, even if physical conditions change locally. With this assumption, the photoionization rate can be obtained from a published atmosphere model and can be used to determine the degree of hydrogen ionization when the temperature and electron density are specified. The application of our method indicates that in the chromospheric environment, plasma features contain more than 10% neutral hydrogen at temperatures lower than 17,000 K but less than 1% neutral hydrogen at temperatures higher than 23,000 K, implying that the hydrogen temperature determined from the Hα line is physically plausible if it is lower than 20,000 K, but may not be real, if it is higher than 25,000 K. We conclude that our method can be readily exploited to obtain a quick estimate of hydrogen ionization in plasma features in the solar chromosphere.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제16권2호
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• pp.104-110
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• 2016

Dense local image descriptors like SIFT are fruitful for capturing salient information about image, shown to be successful in various image-related tasks when formed in bag-of-words representation (i.e., histograms). In this paper we consider to utilize these dense local descriptors in the object tracking problem. A notable aspect of our tracker is that instead of adopting a point estimate for the target model, we account for uncertainty in data noise and model incompleteness by maintaining a distribution over plausible candidate models within the Bayesian framework. The target model is also updated adaptively by the principled Bayesian posterior inference, which admits a closed form within our Dirichlet prior modeling. With empirical evaluations on some video datasets, the proposed method is shown to yield more accurate tracking than baseline histogram-based trackers with the same types of features, often being superior to the appearance-based (visual) trackers.

• Smart Structures and Systems
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• 제15권3호
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• pp.735-749
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• 2015

The major difficulty of using Bayesian probabilistic inference for system identification is to obtain the posterior probability density of parameters conditioned by the measured response. The posterior density of structural parameters indicates how plausible each model is when considering the uncertainty of prediction errors. The Markov chain Monte Carlo (MCMC) method is a widespread medium for posterior inference but its convergence is often slow. The differential evolution adaptive Metropolis-Hasting (DREAM) algorithm boasts a population-based mechanism, which nms multiple different Markov chains simultaneously, and a global optimum exploration ability. This paper proposes an improved differential evolution adaptive Metropolis-Hasting algorithm (IDREAM) strategy to estimate the posterior density of structural parameters. The main benefit of IDREAM is its efficient MCMC simulation through its use of the adaptive Metropolis (AM) method with a mutation strategy for ensuring quick convergence and robust solutions. Its effectiveness was demonstrated in simulations on identifying the structural parameters with limited output data and noise polluted measurements.

• Geomechanics and Engineering
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• 제10권6호
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• pp.807-826
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• 2016

In this study, aiming to investigate the effects of sulfate attack on cement stabilized highly plastic clay; an experimental study was carried out considering the effects of cement type, sulfate type and its concentration, cement content and curing period. Unconfined compressive strength and chloride-ion penetration tests were performed to obtain strength and permeability characteristics of specimens cured under different conditions. Test results were evaluated along with microstructural investigations including SEM and EDS analyses. Results revealed that use of sulfate resistance cement instead of normal portland cement is more plausible for soils under the threat of sulfate attack. Besides, it was verified that sulfate concentration is responsible for strength loss and permeability increase in cement stabilized montmorillonite. Finally, empirical equations were proposed to estimate the unconfined compressive strength of cement stabilized montmorillonite, which was exposed to sulfate attack for 28 days.

• KDI Journal of Economic Policy
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• 제14권1호
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• pp.167-189
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• 1992

북한(北韓)의 GNP를 추정(推定)하는 데에 가장 큰 어려움은 첫째, 통계자료(統計資料)의 절대적(絶對的) 부족(不足), 둘째 GNP의 달러환산(換算)에 적합한 환율(換率)의 부재(不在)이다. 실물지표(實物指標)에 의한 GNP추정방법(推定方法)은 요구(要求)되는 통계(統計)의 양(量)이 많지 않으며, 또한 비교국가군(比較國家群)의 달러GNP와 실물지표(實物指標)들과의 관계를 추정(推定)하여 이를 북한의 실물지표(實物指標)에 적용함으로써 바로 달러GNP를 구할 수 있기 때문에 북한(北韓)GNP 추정(推定)에 특히 적합한 방법이라 하겠다. 실물지표접근법(實物指標接近法)으로 추정(推定)한 결과 1990년 북한(北韓)GNP는 273억(億)달러, 1인당GNP는 1,273달러로 나타났다. 기존의 다른 추정결과(推定結果)들과 비교해 보면 방법론상(方法論上)의 차이(差異)에도 불구하고 실물지표접근법(實物指標接近法), 통일원(統一院), 재정비율접근법(財政比率接近法)의 추정규모가 상당히 비슷한 수준이었으며, GNP추정결과가 시사(示唆)하는 무역규모(貿易規模)/GNP, 재정규모(財政規模)/GNP 비율(比率) 등도 타당(妥當)한 수준이었다. 한편 구소련(舊蘇聯)의 국제경제정치연구소(國際經濟政治硏究所)의 추정GNP는 북한발표(北韓發表) 재정규모(財政規模)보다 작은데다가 무역규모(貿易規模)/GNP 비율이 58%나 되어 GNP가 지나치게 과소평가(過小評價)된 것으로 보이며, 영국(英國)의 국제전략문제연구소(國際戰略問題硏究所)는 추정시(推定時) 과대평가(過大評價)된 공정환율(公定換率)을 사용하였고 추정결과(推定結果)가 시사(示唆)하는 무역규모(貿易規模)/GNP 비율이 7~10%에 불과하여 GNP가 과대평가(過大評價)된 것으로 보인다. 실물지표접근법(實物指標接近法)은 단순추정방법(單純推定方法)(Short-cut method)이 가지고 있는 한계에도 불구하고 북한의 통계사정(統計事情)이 크게 개선될 때까지는 북한(北韓)GNP를 추정(推定)하는 데 유용(有用)할 것으로 판단된다.

• 한국산업정보학회논문지
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• 제17권1호
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• pp.21-29
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• 2012

In this paper, we propose a new method to select colors representing the meaning of text contents based on the cognitive relation between words and colors, Our method is designed on the previous study revealing the existence of crucial words to estimate the colors associated with the meaning of text contents, Using the associative probability of each color with a given word and the strength of color association of the word, we estimate the probability of colors associated with a given text. The goal of this study is to propose a system to recommend the cognitively plausible colors for the meaning of the input text. To build a versatile and efficient database used by our system, two psychological experiments were conducted by using news site articles. In experiment 1, we collected 498 words which were chosen by the participants as having the strong association with color. Subsequently, we investigated which color was associated with each word in experiment 2. In addition to those data, we employed the estimated values of the strength of color association and the colors associated with the words included in a very large corpus of newspapers (approximately 130,000 words) based on the similarity between the words obtained by Latent Semantic Analysis (LSA). Therefore our method allows us to select colors for a large variety of words or sentences. Finally, we verified that our system cognitively succeeded in proposing the colors associated with the meaning of the input text, comparing the correct colors answered by participants with the estimated colors by our method. Our system is expected to be of use in various types of situations such as the data visualization, the information retrieval, the art or web pages design, and so on.