• Journal of Digestive Cancer Research
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• v.10 no.2
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• pp.99-106
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• 2022

Clinical research ultimately aimed to promptly diagnose and prevent diseases through precise biomarker development. Finding the optimal cut-off point of a regularly measured biomarker can help its interpretation and ultimately help in disease investigation and diagnosis, more specifically in determining the presence of diseases. Therefore, this study aimed to use the characteristics of outcome variables in clinical research to explain how to determine the optimal cutoff point. The outcome variables can be divided into dichotomous, ordinal, and survival types. The optimal cut-off point can be determined by finding points that maximize the Youden index, extended Youden index, and log-rank statistics. This study will enable clinical researchers to accurately determine the optimal cut-off points for regularly measured biomarkers, thereby enabling prompt disease diagnosis for effective treatment.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.147-153
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• 2010

Cut-off wall with a low permeability can be constructed to prevent groundwater seepage in spillway tunnel areas. Three spillway tunnels are constructed in Im-ha multipurpose dam region and three types of cut-off walls with a variety of directions and scales are designed. As a result of MODFLOW modeling to assess the effect of cut-off wall for three types, groundwater inflows to the tunnels range from 64.26 $m^3/day$ to 65.49 $m^3/day$ and also they through a cut-off wall section from a reservoir do from 44.08 $m^3/day$ to 45.31 $m^3/day$ and it does not show any significant difference among them. Therefore, a construction process and an environmental conservation rather than the effectiveness of cut-off wall need to be considered to select the best cut-off wall in this region.

• Journal of Nutrition and Health
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• v.33 no.5
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• pp.532-539
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• 2000

The purpose of this research is to assess th iron nutritional status of pregnant women and to evaluate the appropriateness of the present cut off levels of hemoglobin(Hgb), hematocrit(Hct) and total iron binding capacity(TIBC) for assessing iron deficiency status. Pregnant women who were visiting public helath centers in Ulsan were interviewed and agreed to attend the study. Blood sample was taken and biochemical analysis of blood was performed. The collected data were classified into 3 trimesters by gestational age and then statistical analysis was performed. The prevalence of anemia in all subjects was 32.3% by WHO criteria(Hgb < 11.0g/dl) and 17.8% of all subjects was iron deficient anemia by CDC criteria(Hgb < 11.0/dl and serum ferritin < 12.0ug/l). Since the iron deficient anemia generally occures at the last stage of iron deficiency, it is not efficient to diagnose and prevent the iron deficient anemia in pregnant women by using the present cut off level of Hgb. Therefore, the new cut off level of iron status indices is necessary for assessing iron deficiency in early pregnancy before manifestation of anemia and for reducing the prevalence of anemia in later pregnancy. For this reason, the present cut off levels of iron status indices were estimated and compared by assessing the iron deficiency judged by serum ferritin level (<12.0ug/l)as true iron deficiency. It follows from the results of this research that present cut off levels of Hgb, Hct and TIBC were very insensitive in identifying the subjection with iron deficiency. The appropriate cut off levels of Hgb were 11.5g/dl for total period of pregnancy, 12.0g/dl for 1st and 3rd trimester, and 11.5g/dl for 2nd trimester. The cut off level of Hct was 34.0% for total period for pregnancy, 35.0% for 1st trimester, and 34.0% for 2nd and 3rd trimester. The cut off level of TIBC was 400ug/dl for total period, 360ug/dl for 1st 2nd trimester, and 450ug/dl for 3rd trimester.

• Journal of Environmental Health Sciences
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• v.47 no.4
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• pp.320-329
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• 2021

Background: Smoking exposure may be objectively assessed through specific biomarkers. The most common biomarker for smoking is cotinine concentration in urine, and setting an optimal cut-off point can accurately classify smoking status. Such a cut-off point for Korean adolescents has never been studied. Objectives: The aim of this study was to determine a cut-off point for urinary cotinine concentration for the discrimination of smoking in adolescents. Methods: Participants were adolescents aged 13~18 years who participated in the third cycle of the Korean National Environmental Health Survey. We used urine samples to confirm the level of cotinine concentrations. Smoking status was determined by self-reported questionnaire. We identified the optimal cotinine cut-off point for discriminating smoking status using receiver operating characteristic curve analysis. Results: Of the 904 participants, 28 (3.1%) were smokers, among whom 20 (71.4%) were male. The median urinary cotinine concentrations in smokers was 218 ㎍/L (male: 215 ㎍/L, female: 303 ㎍/L), and that in non-smokers was 1.31 ㎍/L (male: 1.46 ㎍/L, female: 1.18 ㎍/L). We found significant differences in urinary cotinine concentration according to smoking status and sex (p<0.001). Urinary cotinine concentrations performed well for identifying smoking adolescents [area under the curve: 0.954 (male: 0.963, female: 0.908)]. The cut-off that optimally distinguished smokers from non-smokers was 39.85 ㎍/L (sensitivity: 89.3%, specificity: 97.4%). Male [39.85 ㎍/L (sensitivity: 90.0%, specificity: 94.9%)] had a different optimal cut-off point than female [26.26 ㎍/L (sensitivity: 87.5%, specificity: 99.6%)]. Conclusions: This study determined a cut-off point for urinary cotinine of 39.85 ㎍/L (male: 39.85 ㎍/L, female: 26.26 ㎍/L) to distinguish smokers from non-smokers in adolescents.

• Survey Research
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• v.5 no.1
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• pp.93-101
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• 2004

In business survey, cut-off sampling is usual, The contribution from cut-off part of the population is at least small in comparison with the remaining population. In this case, part of the target population is excluded from the selection and parameter estimations are only based on Take-all and Take-some stratum. It may be tempting not to use resources on enterprises that contribute little to the overall results of the survey. And this reduces the response burden for these small enterprises. But, the size of cut-off stratum has been increased as a way to manage reduced budgets. This leads to additional bias. In this study, the population have been separated as three stratum, cut -off, take-some, take-all, and we will estimate cut-off part using auxiliary variable.

• Korean Journal of Optics and Photonics
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• v.30 no.1
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• pp.8-14
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• 2019

This paper presents methods to correct and evaluate the chromatic aberration occurring on the cut-off line of a headlamp without additional optical components and alignment process. To correct the chromatic aberration using a geometrical concept, the maximum differences in exit-ray angle between wavelengths are reduced by tilting the convex surface of an aspheric projection lens. To evaluate the chromatic aberration, the position and luminous intensity to be measured are suggested, and the criterion for chromatic aberration is presented through color coordinates. From the evaluation of an automotive headlamp designed using this geometrical method, it is found that the chromatic aberration of the cut-off line is significantly reduced.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.2
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• pp.108-121
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• 2000

This study seeks what kind of factors influence to locate dwellings and to establish scenic spots in nature by a case study focused on a meandering stream. The study specially concentrates on the interrelationship between both residences and beautiful sceneries and a meander cut-off-area that reveals a special topographical characteristics, located at Samji village in Youngyang-eup, Youngyang-gun, Koungsangbuk-do. The meander cut-off area, developed at the middle or upper reaches of a river, often makes up specific landscapes such as precipitous cliffs, sheer cliffs and caves. And the area where is specially created by sudden change of flow due to erosion ;perceived by the cut surface to be the most beautiful scenic spot. These beautiful landscapes were used to be called as Dae, Dam or Gul and managed by Confucian scholars who enjoy refined taste and devote themselves to the study in nature. Moreover, the Ku-Hado-literary means the area of ex-flow-made the scholars' lving with a well prepared basis for agriculture where supplied a cornucopia of organic matters and water. The merit of agriculture made it possible that the scholars became economically independent, and the fact might be the essential point why the meander cut-off area took noticed. Actually, Cho-family has been in Smaji Village for generations, producing a large number of scholars and keeping the actual power of the region. The physical shape of the meander cut-off area, cozily surrounded by mountains, is considered as a good place for the dwelling due to the influence of traditional sight of view for location and P'ungsuchiri which is known as Feng Shui in China and geomancy in the western world. It is a fruit in it own way that we could find the ancestors' discernment and wisdom from this study, who have lived their lives adapting themselves to the given natural environment and also utilizing the nature wisely. But this is a current-argued study on the meander cut-off area. Follow-up studies have to be continued about the landscapes of the meander streams and the meander cut-off areas scattered all over the country except Samji Village and draw the characteristics from the comparative analysis.

• The Journal of the Acoustical Society of Korea
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• v.1 no.1
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• pp.37-44
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• 1982

In the mixed layer when the frequency approaches the cut-off frequency for the first mode of notmalmode theory, sound ceases to be trapped. Based on the data of surface sound velocities abtained during the period of 16 years in the Sea of Japan. A new cut-off frequency coefficient in the surface duct that will determine the miximum wave length for duct transimission of underwater sound has been calculated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.21-21
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• 2000

Thrust Cut-Off 시스템은 로켓 발사체의 분리시의 충격에 의한 비행방향오차 및 비행거리를 감소하고 Pay-Load 부에 추진력을 증가시키고 분리된 추진 기관부의 낙하위치 예측을 용이하게 한다. 이와 같이 중요한 역할을 하게되는 Thrust Cut-Off 시스템에서 스냅링은 핵심적인 역할을 하게 된다. 정상적인 추진체의 작동 시에는 고압의 연소가스를 지탱하고 분리 시에는 쉽게 분리되어 연소가스를 역 분사 시켜야한다.(중략)

• The Journal of Pediatrics of Korean Medicine
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• v.24 no.2
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• pp.99-111
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• 2010

Objectives The objectives of this study were to evaluate the correlations between the indices of obesity and percentage body fat by bioelectrical impedance analysis(BIA). Also, this study was designed to define the cut off values of percentage body fat by BIA which would represent BMI and degree of obesity in order to detect overweight and obesity in preschool children. Methods The height and weight of 683 children aged four to six years old were measured. Also, percentages of body fat were measured by BIA. Results There were high correlations between the boy's body fat percentages and degree of obesity(r=790). Also, there were high correlations between the girl's body fatpercentages and BMI(r=778). The cut off values of body fat percentage, which would correspond to those of BMI percentiles, were calculated by ROC curve analysis. To classify as an overweight, the correspondent cut off values of body fat percentage were 19.55% in boys and 22.35% in girls. For obesity, the cut off values were 28.80% in boys and 27.60% in girls. The cut off values of body fat percentage, which would correspond to degree of obesity were calculated by ROC curve analysis. To classify as an overweight, the correspondent cut off values of body fat percentage were 19.75% in boys and 22.35% in girls. For obesity, the cut off values were 29.05% in boys and 28.75% in girls. Conclusions According to the BMI criteria by the Korean pediatrics society in 2007, the most appropriate cut off values of body fat percentage in for four to six years old children were follows; for boys, 19.55% considered as overweight, and 28.80% as obese while for girls, 22.35% considered as overweight and 27.60% as obese. According to suggested degree of obesity criteria, the most appropriate cut off values of body fat percentage in for four to six old children were were follows; For boys, 19.75% was considered as overweight, and 29.05% as obesity. For girls, 22.35% was considered as overweight, and 28.75% as obese.