• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1489-1496
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• 2013

Consider the ROC surface which is a generalization of the ROC curve for three-class diagnostic problems. In this work, we propose ve criteria for the three-class ROC surface by extending the Youden index, the sum of sensitivity and specificity, the maximum vertical distance, the amended closest-to-(0,1) and the true rate. It may be concluded that these five criteria can be expressed as a function of two Kolmogorov-Smirnov statistics. A paired optimal thresholds could be obtained simultaneously from the ROC surface. It is found that the paired optimal thresholds selected from the ROC surface are equivalent to the two optimal thresholds found from the two ROC curves.

• Communications of the Korean Mathematical Society
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• v.22 no.2
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• pp.173-181
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• 2007

Using the belongs to relation ($\in$) and quasi-coincidence with relation (q) between fuzzy points and fuzzy sets, the concept of ($\alpha,\;\beta$)-fuzzy subalgebras where $\alpha,\;\beta$ are any two of $\{{\in},\;q,\;{\in}\;{\vee}\;q,\;{\in}\;{\wedge}\;q\}$ with ${\alpha}\;{\neq}\;{\in}\;{\wedge}\;q$ was introduced, and related properties were investigated in [3]. As a continuation of the paper [3], in this paper, the notion of a fuzzy subalgebra with thresholds is introduced, and its characterizations are obtained. Relations between a fuzzy subalgebra with thresholds and an (${\in},\;{\in}\;{\vee}\;q$)-fuzzy subalgebra are provided.

• The Journal of Korean Physical Therapy
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• v.12 no.3
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• pp.339-347
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• 2000

To elucidate pressure pain threshold of pericranial muscle due to involuntary. the effect of 30 min or forward head position(FHP) was studied in 20 patients with episodic tension-type headache and in 20 control without headache. Pressure pain thresholds were recorded before and after the FHP. and evaluated by pressure algometry. Thresholds increased in the patients and control after FHP. Relation between thresholds in patients anf control before FHP were not significant differences, but thresholds increased in patients after FHP. So, involutary muscle contraction due to FHP may be effect pressure pain threshold or pericranial muscle.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.193-203
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• 1999

The corrosion of steel reinforcements in concrete is of great concern in recent years. This study is focused on the corrosion behavior of steel bars induced by internal chlorides in concrete at early ages. The main objective of this study is to determine the chloride thresholds causing depassivation and active corrosion of steel reinforcement in concrete. To examine the threshold concentration of chloride ion, the half-cell potential, chemical composition of expressed pore solutions of concrete and the rate of corosion area of the specimens were measured. Major variables include the added amount of chlorides in concrete, types of binders, and water-to-binder ration. From the present comprehensive experimental results, the factors influencing chloride-induced corrosion are investigated, and the chloride thresholds causing active corrosion of steel bars are proposed. The present study will enable to specify the realistic chloride limit in concrete which can be used in the future technical specification.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.507-508
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• 2013

International Roughness Index (IRI) has been widely used by state DOTs to quantify pavement smoothness. When pavement condition falls below certain IRI thresholds, corresponding pavement maintenance treatments should be considered for application. Selection of appropriate IRI thresholds is essential to tactical allocation of limited resources to improve the conditions of states' roadway systems. This selection process is often challenging, however, because IRI thresholds are largely determined by Perceived Ride Quality (PRQ), and PRQ differs in each state. In this paper, a framework is proposed to address this problem. Passenger raters will be randomly selected from predetermined geographic locations, and their PRQ ratings collected. Taking this perceived ride data, along with other data collected, a statistical analysis will be conducted to establish the relationship between measured IRI values and PRQ. Appropriate IRI thresholds will then be determined. Once this framework is implemented, state DOTs could make informative maintenance decisions, which are expected to greatly enhance the public perception of pavement conditions in today's challenging economy.

• Korean Journal of Community Nutrition
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• v.21 no.1
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• pp.75-83
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• 2016

Objectives: The purpose of this study was to analyze correlation thresholds and assessment for salty taste and high-salt dietary behaviors by age. Methods: A total of 524 subjects including 100 each of elementary school students, middle school students, college students, and elderly as well as 124 adults were surveyed for detection and recognition thresholds, salty taste assessments, and high-salt dietary behaviors. Results: Elementary students had a lower detection threshold (p<0.05) and recognition threshold (p<0.01) than did the other groups. Salty taste assessments were lowest among elementary students, followed by middle school students, while college students, adults, and elderly had higher assessment score (p<0.001). Elementary students had significantly lower scores for high-salt dietary behavior than did middle school students, college students, adults and elderly (p<0.001). Middle school students had higher scores for high-salt dietary behavior than did elementary school students and elderly (p<0.001) but no meaningful difference was found in dietary behavior scores between college students, adults, and elderly. There were positive correlations between high-salt dietary behavior and detection thresholds (p<0.001), recognition thresholds (p<0.001), and salty taste assessment (p<0.001). High-salt dietary behavior was more positively correlated with salty taste assessment than detection and recognition thresholds for salty taste. Conclusions: This study suggested that salty taste assessments were positively associated with scores for the detection and recognition thresholds and high-salt dietary behavior.

• Journal of the Korean Data and Information Science Society
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• v.25 no.4
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• pp.857-868
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• 2014

Data mining is the representative analysis methodology in the era of big data, and is the process to analyze a massive volume database and summarize it into meaningful information. Association rule technique finds the relationship among several items in huge database using the interestingness measures such as support, confidence, lift, etc. But these interestingness measures cannot be used to establish a causality relationship between antecedent and consequent item sets. Moreover, we can not know association direction by them. This paper propose causally confirmed association thresholds to compensate for these problems, and then check the three conditions of interestingness measures. The comparative studies with basic association thresholds, causal association thresholds, and causally confirmed association thresholds are shown by simulation studies. The results show that causally confirmed association thresholds are better than basic and causal association thresholds.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.1
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• pp.19-24
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• 1999

This paper is second part on the auditory thresholds and fish behaviors to the underwater sounds for luring of target species at the set-net in the coast of Cheju. In order to obtain the critical ratio of yellow tails(Seriola quinqueradiata) and the emission level of underwater sound for luring of them, we make experiments to measure the auditory threshold of them using conditioning with electric shock. In state that the white noise with 10dB higher sound pressure level than ambient noise is emitted, the auditory thresholds of yellow tails are measured with 100~116.5dB and they are higher than those in state of no emission of white noise by the masking effects of it. Although sound pressure level of background noise go down, the auditory thresholds go up with frequency above than 300Hz.The critical ratio of yellow-tails in frequency of 80Hz, 100Hz, 200Hz, 500Hz, 800Hz are 46dB, 40dB, 50dB, 52dB, 60dB, 70dB respectively. The sound pressure level of which the signal sound is recognized by yellow tails under the ambient noise is above 100dB and the critical ratio of them is above 40dB.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.3
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• pp.301-305
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• 2014

PURPOSE: The purpose of this study was to determine the optimal thresholds of serum lipid level related to hypertension according to age in Korean adults. METHODS: In total, 564 adults who visited the health examine center in general hospital were included. The blood pressure and lipid profiles of low density lipoprotein cholesterol(LDL), high density lipoprotein cholesterol (HDL), triglyceride(TG) were measured. Receiver operating characteristic (ROC) curve were used to establish optimal thresholds between blood pressure and lipid profiles. RESULTS: The optimal TG cutoff value were 110.50(mg/dl) in the 18-39 and 81.50(mg/dl) in the 40-59 age group, and optimal cutoff value of LDL were 126.50(mg/dl) in the 40-59 age group and 111.00(mg/dl) in the 60 and over age group. There was a negative correlation between HDL and hypertension, a higher HDL decreased hypertension. The optimal cutoff value of HDL was 49.50(mg/dl) in the 18-39 age group. CONCLUSION: The thresholds of hypertension were lower in LDL and TG with aging. This result indicated that elderly people needs to concern more about their lipid profiles to maintain healthy cardiovascular function.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.6
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• pp.579-586
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• 2011

It is very critical for image processing of IIR (Imaging Infrared) seekers to achieve improved guidance performance for missile systems to determine appropriate thresholds in various environments. In this paper, we propose automatic threshold determination methods for proper thresholds to extract definite target signals in an EOCM (Electro-Optical Countermeasures) environment with low SNR (Signal-to-Noise Ratios). In particular, thresholds are found to be too low to extract target signals if one uses the Otsu method so that we suggest a Shifted Otsu method to solve this problem. Also we improve extracting target signal by changing Shifted Otsu thresholds according to the TBR (Target to Background Ratio). The suggested method is tested for real IIR images and the results are compared with the Otsu method. The HPDAF (Highest Probabilistic Data Association Filter) which selects the target originated measurements by taking into account of both signal intensity and statistical distance information is applied in this study.