• Journal of the Korean Data and Information Science Society
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• 제17권4호
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• pp.1349-1364
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• 2006

An analytic approach that provides explicit estimates of risk on cataract and epilation data is evaluated by reasonableness of conceivable relative risk models regarding a simple, odds, logistic or Gompertz regression method, assuming a binomial distribution. In these analyses, we apply relative risk models with two thresholds between epilators and nonepilators from a highly characteristic lesion of which radiation cataract does not occur around 2 gray for a single acute exposure. The risk models are fitted to the data assuming 10 as a constant relative biological effectiveness of neutron. The likelihood of observing the entire data set in these models fitted is evaluated by an individual binary-response array. Estimation of a threshold with or without severe epilation and the 100 ($1-\alpha$)% confidence limits are derived from the maximum likelihood approach. The relative risk model with two thresholds can be expressed as a formula with structure of Background $\times$ RR, where RR includes threshold models with or without epilation. The radiosensitivity of ionizing radiation to cataracts has been examined for the relationship between epilators and nonepilators.

• 한국도로학회논문집
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• 제20권1호
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• pp.19-25
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• 2018

PURPOSES : The purpose of this study is to identify the road-subsidence mechanism in unsaturated sandy soils. METHODS : A series of soil chamber tests were conducted under various conditions. RESULTS : The cavity-expansion characteristics in unsaturated sandy soils due to seepage were affected by the outlet size, seepage intensity, relative density, and fine content. CONCLUSIONS : In unsaturated sandy soils, the cavity-expansion speed was affected by the outlet size, relative density, seepage intensity, and clay content; however, the cavity-expansion shape was very similar. As the outlet size and seepage intensity increased, the cavity-expansion speed increased. As the relative density increased, the cavity-expansion speed increased because of a sudden decrease in shear strength, resulting from the increased saturation (reduction of matric suction). The cavity expanded faster with the increasing clay content, up to a certain threshold. It expanded at a slower rate once it passed the threshold. Finally, it reached a stable state where the cavity did not expand due to seepage.

• 대한음성학회지:말소리
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• 제60호
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• pp.109-123
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• 2006

Since computing the log-likelihood of Gaussian mixture density is a major computational burden for the speech recognizer based on the continuous HMM, several techniques have been proposed to reduce the number of mixtures to be used for recognition. In this paper, we propose a modified Bucket Box Intersection (BBI) algorithm, in which two relative thresholds are employed: one is the relative threshold in the conventional BBI algorithm and the other is used to reduce the number of the Gaussian boxes which are intersected by the hyperplanes at the boxes' edges. The experimental results show that the proposed algorithm reduces the number of Gaussian mixtures by 12.92% during the recognition phase with negligible performance degradation compared to the conventional BBI algorithm.

• 한국안전학회지
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• 제15권3호
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• pp.1-6
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• 2000

In fatigue crack growth test, it is important not only to analyze characteristics of fatigue crack growth but also to determine the threshold stress intensity factor, ${\Delta}K_{th}$. which is the threshold value of fatigue crack growth. Linear regression analysis using fatigue test data near the threshold is suggested to determine the ${\Delta}K_{th}$ in the standard test method but the ${\Delta}K_{th}$ can be affected by a fitting method. And there are some limitations on the linear regression analysis in the case of small number of test data near the threshold. The objective of this study is to investigate differences of the ${\Delta}K_{th}$ due to regression analysis method and to evaluate the relative error range of the ${\Delta}K_{th}$ in same fatigue crack growth test data.

• 대한전자공학회논문지
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• 제17권2호
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• pp.10-14
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• 1980

본 논문에서는 DH-laser diode의 threshold current를 계산하기 위하여 2차고조파 왜곡 (se cond harmonic distortion)에 대해 Rate 방정식 (Rate-equation)을 동적상태와 정적상태 방정식으로 연릴하여 계산하였다. 특히 고조파 왜곡 ( )을 계산하는데 바이어스 전류 에 대하여 변조 전류 을 변조계수 m으로 놓고 (Jm=mJo)계산하여 주입전류 J가 Jth에서 2차 고조파 왜곡이 최대치를 가짐을 보여 ,이제까지 알려진 Jth조사 방법보다 간편하고 정확하게 조사할 수 있음을 제시하였다.

• 한국재료학회지
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• 제21권4호
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• pp.196-201
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• 2011

It is known that the relative dielectric constant of insulating polyethylene matrix composites with conducting materials (such as carbon black and metal powder) increases as the conducting material content increases below the percolation threshold. Below the percolation threshold, dielectric properties show an ohmic behavior and their value is almost the same as that of the matrix. The change is very small, but its origin is not clear. In this paper, the dielectric properties of carbon black-filled polyethylene matrix composites are studied based on the effect medium approximation theory. Although there is a significant amount of literature on the calculation based on the theory of changing the parameters, an overall discussion taking into account the theory is required in order to explain the dielectric properties of the composites. Changes of dielectric properties and the temperature dependence of dielectric properties of the composites made of carbon particle and polyethylene below the percolation threshold for the volume fraction of carbon black have been discussed based on the theory. Above the percolation threshold, the composites are satisfied with the universal law of conductivity, whereas below the percolation threshold, they give the critical exponent of s = 1 for dielectric constant. The rate at which the percentages of both the dielectric constant and the dielectric loss factor for temperature increases with more volume fraction below the percolation threshold.

• 대한원격탐사학회지
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• 제37권1호
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• pp.69-84
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• 2021

Awareness of boats is a main issue in areas of fishery management, illegal fishing, and maritime traffic, etc. For the awareness, Automatic Identification System (AIS) and Vessel-Pass System (V-PASS) have been widely used to collect the boat-related information. However, only using these systems makes it difficult to collect the accurate information. Recently, satellite-based data has been increasingly used as a cooperative system. In 2015, U.S. National Oceanic and Atmospheric Administration (NOAA) developed a boat detection algorithm using Visible Infrared Imaging Radiometer Suite (VIIRS) Day & Night Band (DNB) data. Although the detections have been widely utilized in many publications, it is difficult to estimate the night-time fishing boats immediately. Particularly, it is difficult to estimate the threshold due to the lunar irradiation effect. This effect must be corrected to apply a single specific threshold. In this study, the moon phase was considered as the main frequency of this effect. Considering the moon phase, relational expressions are derived and then used as offsets for relative correction. After the correction, it shows a significant reduction in the standard deviation of the threshold compared to the threshold of NOAA. Through the correction, this study can set a constant threshold every day without determination of different thresholds. In conclusion, this study can achieve the detection applying the single specific threshold regardless of the moon phase.

• 대한물리의학회지
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• 제18권3호
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• pp.113-119
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• 2023

PURPOSE: This study aimed to determine the effects of using a smartphone in the sitting position on the pelvic posture and the low back pressure pain threshold (PPT). METHODS: Thirty participants (15 women and 15 men) were recruited for this study. The participants were asked to sit in a normal sitting position without using a smartphone, followed by sitting while watching a video using a smartphone. The pelvic posture was measured using the back range of motion II (BROM II) device and a palpation meter. We measured PPT using the digital pressure algometer. RESULTS: Pelvic posterior tilting was significantly greater when sitting while using a smartphone relative to sitting without using a smartphone (p < .05). There was no significant difference in the height of the iliac crest when sitting while using a smartphone compared to sitting without using a smartphone (p > .05). The PPTs of L1, L3, and L5 were significantly lower when sitting while using a smartphone relative to sitting without using a smartphone (p < .05). CONCLUSION: Based on these results, it can be concluded that frequent smartphone use while sitting may potentially increase the risk of developing low back problems.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.274-281
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• 2004

In this paper, the existing Stokoe type torsional shear equipment is modified to saturate the specimen and measure excess pore water pressure during undrained testing. Two types of sands, Geumgang and Toyoura sands, were collected and TS tests were performed at various densities drainage conditions, and confining pressures. The cyclic threshold shearing strains were estimated based on the variations of shear modulus, material damping ratio and pore pressures with loading cycles. The effects of relative density, confining pressure, and drainage condition on the cyclic threshold shearing strains were investigated.

• 한국재료학회지
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• 제20권5호
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• pp.271-277
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• 2010

In this paper two aspects of the percolation and conductivity of carbon black-filled polyethylene matrix composites will be discussed. Firstly, the percolation behavior, the critical exponent of conductivity of these composites, are discussed based on studying the whole change of resistivity, the relationship between frequency and relative permittivity or ac conductivity. There are two transitions of resistivity for carbon black filling. Below the first transition, resistivity shows an ohmic behavior and its value is almost the same as that of the matrix. Between the first and second transition, the change in resistivity is very sharp, and a non-ohmic electric field dependence of current has been observed. Secondly, the electrical conduction property of the carbon black-filled polyethylene matrix composites below the percolation threshold is discussed with the hopping conduction model. This study investigates the electrical conduction property of the composites below the percolation threshold based on the frequency dependence of conductivity in the range of 20 Hz to 1 MHz. There are two components for the observed ac loss current. One is independent of frequency that becomes prevalent in low frequencies just below the percolation threshold and under a high electrical field. The other is proportional to the frequency of the applied ac voltage in high frequencies and its origin is not clear. These results support the conclusion that the electrical conduction mechanism below the percolation threshold is tunneling.