• Korean Journal of Clinical Laboratory Science
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• v.50 no.3
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• pp.253-260
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• 2018

With the growing prevalence of dyslipidemia in adolescents, its early detection and management is becoming increasingly important. This study overviewed the fasting lipid concentration distribution of adolescents according to the sex and age, and reviewed the percentile of its reference interval. This study targeted 2,713 adolescents aged between 10 and 19 (1,436 boys, 1,275 girls) based on the data from 2013 to 2016, Korean Health and Nutrition Examination Survey. The mean fasting lipid concentration of total cholesterol, LDL cholesterol, HDL cholesterol, non-HDL cholesterol, and triglyceride of girls was higher than those of boys. Although the $95^{th}$ percentile of the cholesterol value was 200 mg/dL in boys, which was equivalent to the diagnosis criterion, the mean value of girls was 208 mg/dL, staying between the $90^{th}$ and $95^{th}$ percentiles. The $95^{th}$ percentiles of the LDL cholesterol, non-HDL cholesterol, and triglyceride value were 123, 148, and 147 mg/dL in boys, respectively, and 131, 149, and 139 mg/dL in girls, respectively. Most of the criteria of dyslipidemia were at the proper level, within the $90^{th}$ and $95^{th}$ percentile. While the criteria of LDL cholesterol (130 mg/dL) was higher in boys, the triglycerides was higher in girls. In conclusion, criteria more suitable to Korean adolescents will need to be established with further studies.

• Journal of the Korean Society of Radiology
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• v.84 no.5
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• pp.1080-1090
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• 2023

Purpose This study aimed to compare the volume and normative percentiles of brain volumetry in the Korean population using quantitative brain volumetric MRI analysis tools NeuroQuant^Ⓡ (NQ) and DeepBrain^Ⓡ (DB), and to evaluate whether the differences in the normative percentiles of brain volumetry between the two tools is related to cranial shape. Materials and Methods In this retrospective study, we analyzed the brain volume reports obtained from NQ and DB in 163 participants without gross structural brain abnormalities. We measured threedimensional diameters to evaluate the cranial shape on T1-weighted images. Statistical analyses were performed using intra-class correlation coefficients and linear correlations. Results The mean normative percentiles of the thalamus (90.8 vs. 63.3 percentile), putamen (90.0 vs. 60.0 percentile), and parietal lobe (80.1 vs. 74.1 percentile) were larger in the NQ group than in the DB group, whereas that of the occipital lobe (18.4 vs. 68.5 percentile) was smaller in the NQ group than in the DB group. We found a significant correlation between the mean normative percentiles obtained from the NQ and cranial shape: the mean normative percentile of the occipital lobe increased with the anteroposterior diameter and decreased with the craniocaudal diameter. Conclusion The mean normative percentiles obtained from NQ and DB differed significantly for many brain regions, and these differences may be related to cranial shape.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.16 no.28
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• pp.137-143
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• 1993

Generally there are three methods to derive an approximation formula: 1) approching standard normal distribution by appropriate changing variable 2) using standardization variable for expansion 3) deriving approximation formula by direct method. This paper present correction terms having the form of $C_{1/v^{n/2}}/{\;}+{\;}C_2{\;}(n=1,2)$ with respect to $x^2_{\alpha}(v)$ distribution (${\nu}{\;}{\leq}{\;}30$), which minimize the error by EDA method and least square method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1245-1256
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• 2014

The physical nature of fatigue shows the considerable amount of scatter from intrinsic and extrinsic factors. In this study, some degradation models, such as the gamma process model, were reviewed in terms of uncertainties associated with the continuous, gradual, and monotonic nature of fatigue crack growth. Statistically varying fatigue crack growth data obtained from Lu and Meeker were used as an example to demonstrate the use of the gamma process model. This model can describe the condition and lifetime as statistical distribution curves whose shapes vary with cycles. From the skewness of the statistical distribution curves, it was confirmed that the median is suitable for being considered as the expected life. The use of the gamma process model enables the optimum replacement period and percentile life to be employed as criteria for preventive maintenance policy.

• The Korean Journal of Applied Statistics
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• v.16 no.2
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• pp.455-467
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• 2003

There has been a long debate on the applicability of the chi-square approximation to statistics based on small sample size. Extending comparison results among Pearson chi-square Χ$^2$, generalized likelihood .ratio G$^2$, and the power divergence Ι(2/3) statistics suggested by Rudas(1986), recently developed disparity statistics (BWHD(1/9), BWCS(1/3), NED(4/3)) we compared and analyzed in this paper. By Monte Carlo studies about the independence model of two dimension contingency tables, the conditional model and one variable independence model of three dimensional tables, simulated 90 and 95 percentage points and approximate 95% confidence intervals for the true percentage points are obtained. It is found that the Χ$^2$, Ι(2/3), BWHD(1/9) test statistics have very similar behavior and there seem to be applcable for small sample sizes than others.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.649-656
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• 2021

The purpose of this study was to evaluate the appropriateness of transverse cerebellar diameter and abdominal circumference (TCD/AC ratio) as variables to evaluate intrauterine growth restriction of the fetus. From April 2019 to March 2021, 784 pregnant women who underwent ultrasound as a regular checkup at I hospital were retrospectively analyzed using the transverse cerebellar diameter and abdominal circumference measurements. In simple regression analysis, transverse cerebellar diameter and abdominal circumference had an effect of 97.2% and 97.5% on gestational age (p<0.001). In addition, the percentile of the TCD/AC ratio for each gestational age group was calculated through frequency analysis, and the 95th percentile of intrauterine growth restriction prediction was 14.2. As a result, it is thought that the TCD/AC ratio can be used as a useful variable to evaluate the normal growth of the fetus and predict the IUGR.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.37-47
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• 2018

The objective of this study was to analyze the influences of forest management activity on the diameter distribution of Larix kaempferi Carriere stands in South Korea. We used 232 managed stands data, 47 unmanaged stands data of National Forest Inventory for this study. We employed the Weibull distribution function for estimating diameter based on percentiles and parameter recovery method. The results revealed that the average diameter breast height movements and growth of tree in the managed stands higher than the unmanaged stands according to the scenario: age, site index, and tree density change. The finding shows the percentage of the total amount of large class diameter was also high in the managed stands. The results of this study could be apply for the estimation of multi-products of timbers per diameter classes and stand structure development for Larix kaempferi Carriere stands in South Korea.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.495-496
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• 2011

본 연구의 목적은 스포츠분야에 활용 가능한 다양한 체력요인들을 수집하고 이를 효과적으로 활용하기 위한 웹기반의 서비스 플랫폼을 개발하는 것이다. 선행연구를 통해 확보한 체력요인에 대한 데이터를 통해 성별, 연령별로 구분된 체력요인별 수준을 백분위수를 제시하였고 각각의 체력수준을 다섯 등급으로 구분하여 체력수준의 등급을 제시하였다. 또한 특정 체력요인의 수치를 입력하면 해당 요인에 대한 체력 수준 및 그 수준에 따른 다른 체력요인들을 검색하여 제공함으로써 체력요이들을 비교할 수 있게 하였다. 뿐만 아니라 웹 기반 형태의 플랫폼 형태는 추후 다양한 서비스 콘텐츠의 추가가 가능할 것이다. 개발된 서비스플랫폼은 자산의 체력수준 확인, 체력검사의 기준, 스포츠용품의 성능 검증 등 다양한 스포츠과학분야의 기반 데이터로서 활용 가능할 것이다.

• Journal of Korean Society of Transportation
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• v.16 no.2
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• pp.67-76
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• 1998

본 연구는 현행 오르막차로 설계기준이 적정한지를 검증하고 오르막차로 설계기준 제시에 목적을 두고 있다. 오르막차로와 본선에 대한 현장의 속도분포와 화물차량의 합류형태를 바탕으로 오르막차로 설계기준을 검증하고 개발하였으며, 주요 연구결과를 요약하면 다음과 같다. 첫째, 설계속도 120km/h에서 화물차의 50백분위비율과 85백분율은 각각 66km/h와 76km/h로 나타났기 때문에 현행 설계속도 80km/h 이상의 구간에서 화물차의 허용최저속도를 60km/h로 규정하고 있는 것을 설계속도 기준을 세분화하여 설계속도가 100km/h 이상인 구간에서는 화물차의 허용최저 속도를 70km/h로 함이 타당한 것으로 도출되었다. 둘째, 설계속도 80km/h인 구간에서의 화물차 허용최저속도는 60km/h로 규정한 것이 적정하다고 확인되었다. 셋째, 설계속도 80km/h 미만의 구간에서 화물차의 허용최저속도는 설계속도에서 20km/h를 감한값을 사용하는데, 이 때 20km/h 감속을 한계속도 기준으로 사용하는 것이 적정하다고 확인되었다.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.193-201
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• 2010

Early childhood caries (ECC) is a comprehensive terminology that includes nursing bottle caries and rampant dental caries occurred in infants and children. In previous studies, ECC was thought to affect body growth of children negatively. The purpose of this study was to evaluate the effect of ECC on body growth of children in respect of their chronologic age and degree of dental caries. Height and body weight were used as means for physical growth measurements. Children, who visited the pediatric department of Yonsei University Dental Hospital, received oral and physical examinations, and they were divided into the control and ECC groups. Then, each group was subdivided according to their age and gender. Two-sample T test was used to compare the mean height and body weight of the control and ECC groups, and Likelihood Ratio Chi-square test was used to compare their growth percentile distribution. When the mean height and weight were compared, there was a common tendency observed even though statistical significance was not found in all cases. Before the age of 3-4, the mean height and weight tended to be greater in the ECC groups compared to the control groups, whereas after the age of 3-4, the mean height and weight of the ECC group tended to be less compared to the control group. In addition, in groups with age equal or greater than 3-4, which presented significant difference in height and body weight, the percentage of children showing less than 3 percentile growth was greater in the ECC group than the control group. These results imply the negative effects of the ECC on physical growth of the infants and children, and its effects on physical growth may present different characteristics according to chronologic age of the patients.