• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10b
• /
• pp.668-673
• /
• 1998

The specimen of current study has the same type with the 3-span slabs of Burns et al used in the study by Mojtahedi/Gamble, which laid a ground for the revision of the ACI318-77 code to the ACI 318-83 code. But those specimens was failed prematurely before it reached the ultimate strength which the specimen had. The reason is that bonded reinforcements were cut off where there is no need for the flexural reinforcement. As results. the slabs failed ultimately where the reinforcements was cut off. Thus, the tendon stresses of failure may have been much smaller than the values which culd reach if the bonded reinforcements were extended beyond the theoretical cut off points. On the based on the fact mentioned above. the specimens which had the same conditions as the specimens of Burns et al were used in the current study, but in which the reinforcements were distributed in a sequence for the reinforcements not to be cut anywhere in the 3-span. As a results, it was known that the current ACI code, revised by the result of Mojtahedi/Gamble's study, overestimated the effect of span/depth ratio on the members with high span/depth ratio. Thus it was concluded that the effect of span/depth ratio on the ultimate stress of unbonded tendon regulated by the current ACI code must be reconsidered and reevaluated.

• Journal of Preventive Medicine and Public Health
• /
• v.30 no.4 s.59
• /
• pp.741-751
• /
• 1997

Measurement of blood lead (PbB) and blood zinc protoporphyrin (ZPP) are most common biological indices to identify the individual at risk for excess or the health sequences by lead exposure. Because PbB is known most important and reliable index of lead exposure, PbB is often regarded as a gold standard to detect lead exposure. But in Korea PbB is a secondary test item of detailed health check-up with positive finding of screening test in most occasion. Our lead standard requires all lead workers to take annual heath-check twice a year for investigation of their health effect due to lead exposure. Blood ZPP is one of most important index to detect high lead absorption in lead workers as a screening test. Measurement of blood ZPP is known ,well to correlate with PbB in steady state of exposure in most lead workers and is often used as a primary screening test to detect high lead absorption of lead workers with the advantage of simplicity, easiness, portability and low cost. The current cut-off criteria of blood ZPP for further detailed health check-up is $100{\mu}g/d\ell$ which is supposed to match the level of $40{\mu}g/d\ell$ of PbB according to our standard. Authors tried to investigate the validity of current criteria of cut-off level $(100{\mu}g/d\ell)$ of blood ZPP and possible another better cut-off level of it to detect the lead workers whose PbB level over $40{\mu}g/d\ell$. The subjects in our study were 212 male workers in three small scale storage battery industries. Blood ZPP, PbB and hemoglobin (Hb) were selected as the indices of lead exposure. The results were as follows. 1. The mean of blood ZPP, PbB and Hb in lead workers were $79.5{\pm}46.7{\mu}g/d\ell,\;38.7{\pm}15.1{\mu}g/d\ell,\;and\;14.8{\pm}1.2g/d\ell$, respectively. There were significant differences in blood ZPP, PbB and Hb by industry (P<0.01). 2. The percents of lead workers whose blood ZPP were above $100{\mu}g/d\ell$ in the group of work duration below 1, 1-4, 5-9 and above 10 years were 8.6%, 17.2%, 47.6%, and 50.0%, respectively. The percents of lead workers whose PbB were above $40{\mu}g/d\ell$ in those were 31.4%, 40.4%, 71.4%, and 86.4%, respectively. 3. The percents of lead workers whose PbB were below $40{\mu}g/d\ell$, $40-59{\mu}g/d\ell$ and above $60{\mu}g/d\ell$ were 54.7%, 34.9% and 10.4%, respectively. Those of lead workers whose blood ZPP were below $100{\mu}g/d\ell$, $100-149{\mu}g/d\ell$ and above $150{\mu}g/d\ell$ were 79.2%, 13.7% and 7.1%, respectively. 4. Simple linear regression of PbB on blood ZPP was statistically significant (P<0.01) and as PbB was $40{\mu}g/d\ell$, blood ZPP was $82.1{\mu}g/d\ell$. 5. While the highest sensitivity and specificity of blood ZPP test to detect lead workers with PbB eve. $40{\mu}g/d\ell$ were observed in the cut-off level of $50{\mu}g/d\ell$ and $100{\mu}g/d\ell$ of blood ZPP, respectively, the highest validity (sensitivity+specificity) of blood ZPP to detect lead workers with PbB over $40{\mu}g/d\ell$ was observed in the cut-off level of around $70{\mu}g/d\ell$ of blood ZPP. But even with optimal cut-off level of around $70{\mu}g/d\ell$ of blood ZPP, still 25.0% of false negative and 20.7% false positive lead workers were found. As the result of this study, it was suggested that reconsideration of current blood ZPP cut-off of our lead standard from $100{\mu}g/d\ell$ to somewhat lower level such as around $70{\mu}g/d\ell$ and the inclusion of PbB measurement as a primary screening test for lead workers was highly recommended for the effective prevention of lead workers.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.16
• /
• pp.6923-6928
• /
• 2015

Background: Early detection of various kinds of cancers nowadays is needed including colorectal cancer due to the highly significant effects in improving cancer treatment. The aim of this study was to evaluate the potential value of adiponectin, visfatin and resistin as early biomarkers for colorectal cancer patients. Materials and Methods: Serum levels of adiponectin, visfatin and resistin were measured by a sandwich-enzyme-linked (ELISA) assay technique in 114 serum samples comprising 34 patients with colorectal cancer (CRC), 27 with colonic polyps (CP), 24 with inflammatory bowel disease (IBD) and 29 healthy controls. The diagnostic accuracy of each serum marker was evaluated using receiver-operating characteristic (ROC) curve analysis. Results: The mean concentration of adiponectin was significantly higher in CRC and CP groups than IBD and control groups (P-value <0.05). Also the mean concentration of serum resistin was significantly elevated in the IBD and control groups compared to CRC and CP groups (P-value = 0.014). However, no significant difference was noted in patients of the CRC and CP groups. On the other hand, the mean concentration of visfatin was significantly elevated in CRC and control groups compared to CP and IBD groups (P-value = 0.03). ROC analysis curves for the studied markers revealed that between CRC and IBD groups serum level of adiponectin had a sensitivity of 76.7% and a specificity of 76% at a cut off value of 3940, +LR being 3.2 and -LR 0.31 with AUC 0.852, while serum level of adiponectin between CP and IBD had a sensitivity of 77.8% and a specificity of 75% at a cut off value of 3300, with +LR=3.11 and -LR = 0.3 with AUC 0.852. On the other hand the serum level of visfatin between CRC and CP groups had a sensitivity of 65.5% and a specificity of 66.7 at a cut off value of 2.4, +LR being 1.67 and -LR 0.52 with AUC 0.698. Also the serum level of resistin had a sensitivity of 62.5% and a specificity of 70.3% at a cut off value of 24500, with +LR=2.1 and -LR = 0.53 with AUC 0.685 between control and other groups. On the other hand by comparing control vs CP groups resistin had a sensitivity of 81.8% and a specificity of 70.8% at a cut off value of 17700, with +LR=2.8 and -LR = 0.26 with AUC 0.763 while visfatin had a sensitivity of 68.2% and a specificity of 70.8% at a cut off value of 2.7, with +LR=2.34 and -LR = 0.0.45 with AUC 0.812. Conclusions: These findings support potential roles of adiponectin, visfatin and resistin in early detection of CRC and discrimination of different groups of CRC, CP or IBD patients from normal healthy individuals.

• Journal of Preventive Medicine and Public Health
• /
• v.28 no.3 s.51
• /
• pp.640-650
• /
• 1995

After the introduction of National Medical Insurance in 1989, the medical demand has rapidly increased. The impact of increased medical demand was followed by an increase in the number of claims in need of review. We studied a new, fair method for reducing the number of claims reviewed. We analysed 90,583 outpatient claims submitted between September and October; claims were made for services given August of 1994. We finally suggested a screening system for claims review using a statistical method of discriminant analysis of the medical costs. The results were as follows. 1. In the cut-off group, age, days of medication, number of hospital or clinic visits, and total charge were significantly high. The cut-off rates according to the hospital-type and existence of accompanied disease were significantly different 2. According to ICD, the cut-off rate was highest in peripheral enthesopathies and allied syndromes(20.76%), lowest in acute sinusitis(0.93%). The mean charges were significantly different according to ICD and existence of cut-off. 3. We build discriminant functions by ICD with such discriminant variables as patient age, sex, existence of accompanied disease, number of hospital or clinic visits, and 9 detailed hospital or clinic charges included in claim. 4. We applied the discriminant function for screening those claims that were expected to be cut-off. The sensitivities comprised from 40% to 70%, and specificities from 70% to 95% by ICD. Acute rhinitis had highest sensitivity(100.00%) and other local infections of skin and subcutaneous tissue had highest specificity(98.45%). The expected number of cut-off was 17,762(19.61%). The total sensitivity was 49.62%, the total specificity was 82.57% and the error rate was 19.66%. We lacked economic analysis such as cost-benefit analysis. But, if the new method of screening claims using discriminant analysis were applied, the number of claims in need of review will reduce considerably.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.12 no.4_1
• /
• pp.129-136
• /
• 1992

A precedure for recovering surface displacement from a time series of pressure measured by a pressure gage in a shallow water (that is, FFTM, LCM. IWM) is investigated with respect to a proper cut-off-frequency of a frequency response function for the accurate recovery of wave height and period. The authors examined the applicability of above mentioned three transformation procedures through field observations and laboratory experiments and the following results are obtained. i) The cut-off-frequency of the frequency response function used in FFTM is deeply depend on both the frequency response of the pressure sensor and the water depth at the sensor. In this study, a relatively accurate surface displacement can be recovered when the frequency response function is cut off at the frequency corresponding to kh=3.0 where k is a wave number at the depth of h. The frequency response function in the region higher than the cut-off-frequency is set constant to be the value at the cut-off-frequency. ii) The transformed surface displacements by LCM are affected by the small waves of short periods included in the measured pressure. It is found that pressure variation whose local frequency is higher than kh=1.5 has to be neglected to recover surface displacement sufficiently. iii) In IWM, the linear pressure response function is usually utilized by multiplying a coefficient N which is a function of the frequency (or kh) and takes a value around unity. However, in this study, a constant value of N(=1.0) gives a relatively accurate recovery of surface displacements.

• Geophysics and Geophysical Exploration
• /
• v.12 no.1
• /
• pp.154-162
• /
• 2009

Sonic wave dispersion characteristics are one of the most important targets of study, particularly in estimating shear wave velocity from borehole sonic logging. We have tested dispersion characteristics using monopole and dipole sources. Theoretical dispersion curves were computed for tool-absent and tool-included models having the same physical properties but different diameters (including ${\Phi}520mm$, ${\Phi}150mm$, and ${\Phi}76mm$). Comparisons were made between boreholes of different sizes and between tool-absent and tool-included models. Between the tool-included and the tool-absent boreholes, a close similarity in dispersion curve shape was revealed for the monopole source, and a significant difference was shown for the dipole source. However, for the cut-off frequency, particularly in the engineering boreholes (${\Phi}76mm$ and ${\Phi}50mm$), a significant difference was observed for signals from the monopole source, but approximately the same cut-off frequencies were found with the dipole source. This indicates the need of careful choice of source frequency in monopole-source sonic logging, particularly in an engineering borehole. The results of numerical experiments show that cut-off frequency is exponentially proportional to the inverse of borehole radius, irrespective of the mode type and the presence of a tool, and that the cut-off frequencies for each borehole environment could be expressed as an exponential function, rather than the inversely proportional relationship between the cut-off frequency and the borehole radius that was previously generally recognised. From the direct comparison of dispersion curves, the effects on the dispersion characteristics of borehole size and the presence of the tool can be revealed more clearly than in previous studies, which presented the dispersion curve and/or characteristics for each borehole environment separately.

• Journal of the Korean Electrochemical Society
• /
• v.7 no.1
• /
• pp.32-37
• /
• 2004

The charge/discharge capacity of natural graphite anode in lithium secondary batteries was examined as a function of charge/discharge rate. When the natural graphite anode was galvanostatically cycled in the range of 0.0-2.0V $(vs.\;Li/Li^+)$, the charging capacity decreased with an increase in the charging rate, which is caused by an earlier approach to the charging cut-off (0.0 V) before the complete charging that is in turn caused by an ever-increasing overpotential at higher rates. Even if the overpotential of discharging reaction also increased at higher discharge rates, the discharging reaction took place in the range of 0.0-0.3 V that is far below the discharge cut-off (2.0 V). As a result, the discharge capacity was not affected by the discharge rate because all the lithium ions once intercalated are fully discharged even at high current condition. As the overpotential of lithium deposition reaction also increased at high current condition, the charge capacity of natural graphite could be enlarged by lowering the charging cut-off voltage below 0.0 V, There is, however, a limitation for the lowering of cut-off voltage because the resistance for lithium deposition is smaller than that of lithium intercalation into graphite. When the charge cut-off voltage was lowered down to -0.04 V under IC condition, lithium ions were inserted into graphite without lithium deposition such that the discharge capacity could be raised up to $11\%$.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.11
• /
• pp.73-82
• /
• 2017

Recently, offshore bucket cut-off walls were developed to solve several problems in conventional offshore cut-off walls. In this study, a numerical analysis was carried out to investigate the seepage stability of offshore bucket cut-off walls. The ground was assumed as uniform homogeneous sand and steady state flow conditions were applied. The flow condition was compared among 2-dimensional flow (2-D), 2-dimensional concentrated flow (2-DC), and axisymmetric flow. The analysis results showed that the seepage velocities in axisymmetric flow were about 1.5 and 2 times larger than those of 2-DC and 2-D flow conditions, respectively. Thereafter, the axisymmetric flow condition was applied because the seepage flow was concentrated toward the center of the circular-shaped wall. A parametric study was performed varying bucket radius, penetration depth, total head difference between in and outside of the wall. The exit gradient, which used for the calculation of piping stability, decreased with increase of the penetration depth and bucket radius. Design charts were proposed to estimate the factor of safety and the exit gradient at various analysis conditions. Finally, the design equation was proposed to calculate the exit gradient for the preliminary design of the bucket cut-off wall.

• Journal of the Korean Society of Radiology
• /
• v.13 no.2
• /
• pp.201-207
• /
• 2019

This study has evaluated whether the method of using the combination of different risk group, according to K-TIRADS classification and K-TIRADS classification in thyroid ultrasonography is useful in a differential diagnosis of benign and malignant nodules. The subject was patients underwent thyroid ultrasonography and retrospective analysis were performed based on the results of fine needle aspiration cytology. A chi-square test was performed for the difference analysis of the score system in K-TIRADS and different risk group according to the benign and malignant of thyroid nodule. The optimized cut off value was determined by the K-TIRADS score and different risk group to predict malignant nodule through ROC curve analysis. In the differential verification result of K-TIRADS and different risk group, according to the classification of benign and malignant nodule group each showed significant difference statistically(p=.001). In the point classification according to K-TIRADS for the prediction of benign and malignant in ROC curve analysis showed AUC 0.786, Cut-off value>2(p=.001), and in the different risk group, it was decided as AUC 0.640, Cut-off value>2(p=.001). When discovering the nodule in thyroid ultrasound, it is considered that the K-TIRADAS which helps in identifying benign and malignant thyroid nodules, it is considered to be helpful in the differential diagnosis of thyroid nodules, than the classification system according to Different risk group, and when applying the classification system according to K-TIRADS, it is considered that it can reduce unnecessary fine needle aspiration cytology and could be helpful in finding the malignant nodules early.

• Journal of The Korean Society of Integrative Medicine
• /
• v.9 no.3
• /
• pp.37-45
• /
• 2021

Purpose : This study aimed to present normative data and cut-off points for older Korean adults completing the Montreal Cognitive Assessment - Korean (MoCA-K), which is used as a screening test for mild cognitive impairment in Korea. Methods : A total of 195 healthy adults ≥60 years were recruited. All participants completed the MoCA-K and the Korean - Mini-Mental State Examination (MMSE-K) to assess their cognitive function. Participants were divided into six groups based on their age: 60-64 years, 65~69 years, 70~74 years, 75~79 years, 80~84 years, and 85~89 years. Results : The results revealed that MoCA-K score decreased significantly with age (mean score ± standard deviation [SD]; 27.63±2.80 in subjects aged 60~64 years; 27.00±2.39 in subjects aged 65~69 years; 24.94±2.96 in subjects aged 70~74 years; 24.74±3.37 in subjects aged 75~79 years; 22.59±4.72 in subjects aged 80~84 years; and 18.83±5.38 in subjects aged 85~89 years; p<.001). Additionally, MoCA-K score also increased significantly with educational level (mean score±standard deviation [SD]; 19.95±4.78 in no formal education group; 24.95±2.22 in elementary school graduated group; 26.35±2.72 in middle school graduated group; 28.32±1.36 in high school graduated group; and 28.50±1.51 in more than college graduated group; p<.001). The optimal cut-off points were 24/25 for 60~69 years old group, 21/22 for 70~79 years old group, 17/18 for 80~84 years old group, and 13/14 for 85~89 years old group. The optimal cut-off points were 15/16 for individuals who were illiterate, 22/23 for individuals with 6 years of education, 22/24 for individuals with 9 years of education, and 26/27 for individuals with 12 or more years of education. Conclusions : This study presents normative data and cut-off points for the MoCA-K in older Korean adults. This data will facilitate more accurate detection and follow-up of the risk of mild cognitive impairment in this population, taking into consideration age and education. Future studies are required that should focus on the cut-off score on the level of education according to age.