• Journal of Korean Society for Quality Management
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• v.23 no.3
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• pp.93-101
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• 1995

We present a brief survey concerning the relations between mean residual life and failure rate. Change points of mean residual life and failure rate are known to be different in general and we explore such situations in this paper. A few parametric models which show bathtub-shaped failure rate are examined in details, including the shape of its corresponding mean residual life function. We give some graphical comparisons of trend changes of mean residual life and failure rate for various choices of parameters for each parametric model.

• Atmosphere
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• v.27 no.4
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• pp.423-433
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• 2017

The spatial and temporal variations in radiative forcing (RF) and mean temperature changes of greenhouse gases (GHGs), such as $CO_2$, $CH_4$, and $N_2O$, were analyzed at urban center (Yeon-dong) and background sites (Gosan) on Jeju Island during 2010~2015, based on a modeling approach (i.e., radiative transfer model). Overall, the RFs and mean temperature changes of $CO_2$ at Yeon-dong during most years (except for 2014) were estimated to be higher than those at Gosan. This might be possibly because of its higher concentrations at Yeon-dong due to relatively large energy consumption and small photosynthesis and also the difference in radiation flux due to the different input condition (e.g., local time and geographic coordinates of solar zenith angle) in the model. The annual mean RFs and temperature changes of $CO_2$ were highest in 2015 ($2.41Wm^{-2}$ and 1.76 K) at Yeon-dong and in 2013 ($2.22Wm^{-2}$ and 1.62 K) at Gosan (except for 2010 and 2011). The maximum monthly/seasonal mean RFs and temperature changes of $CO_2$ occurred in spring (Mar. and/or Apr.) or winter (Jan. and/or Feb.) at the two sites during the study period, whereas the minimum RFs and temperature changes in summer (Jun.-Aug.). In the case of $CH_4$ and $N_2O$, their impacts on the RF and mean temperature changes were very small (an order of magnitude lower) compared to $CO_2$. The spatio-temporal differences in these RF values of GHGs might primarily depend on the atmospheric profile (e.g., ozone profile), surface albedo, local time (or solar zenith angle), as well as their mass concentrations.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.484-491
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• 1999

To estimate annual changes in age adjusted mean of serum cholesterol and cholesterol intake in Korea during the past years, data from 21 literatures regarding for serum cholesterol level of Korean or National Nutrition Survey Reports from 1962 to 1995 were extracted for this study. Age standardization for mean serum cholesterol level was adjusted being based on Korean population composition in 1995. Mean of Korean serum cholesterol level depicted an increasing tendency from 1962 to 1995. Magnitude of changes in mean of serum cholesterol was big in the age old groups over 60th decade, but sex difference in the pattern was not observed. The estimated mean cholesterol intake was higher in the urban population than those of rural's and it increased linearly from 1969 to 1995. Major food sources for cholesterol were egg(39.3%), anchovy(8.3%), seafoods(35.2%) meat(13%) in 1995. From the results, it was estimated that mean serum cholesterol and daily cholesterol intake of Korean would be 178 mg/dl and 278mg/day in 1995, respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.44
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• pp.69-79
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• 1997

We investigate both of central and dispersion tendencies of the observed test statistics in control charts in order to judge whether a production process is abnormal or not. In order to do it, first, we study about detection of changes of the population mean as a central tendency The $\bar{x}$ and x control charts are used for detecting the change of the population mean $\mu$. We shows the probability detecting the change of population mean using the $\bar{x}$ and x control charts. Secondly, we study about detection of changes of the population standard deviation as a dispersion tendency in the s control chart. In our studies, for the given several parameters the detection probabilities of changes of central and dispersion tendencies are calculated, the necessary sample size values n are suggested for detecting the changes, and their informations are given as various tables.

• Biomedical Science Letters
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• v.23 no.3
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• pp.208-214
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• 2017

To investigate the effects of strenuous physical exercise on commonly used hematological markers in subjects the intensive long running. Blood samples were obtained from nineteen participants in a 622 km ultra-marathon race before, 300 km and immediately after completion of the 622 km ultra-marathon. Samples were analyzed for total white cell count (WBC) and differential, total red cell count (RBC), hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), red cell distribution width (RDW), platelets, mean platelets volume (MPV), platelets distribution width (PDW). Significant increases were found in WBC, neutrophil and platelets at 622 km compared to the pre-race. RBC, hemoglobin and hematocrit decreased statistically significantly the race at 300 km and 622 km compared to pre-race. A wide range of hematological perturbations occur during 622 km ultra-marathon running but it was physiological changes within a reference range. The 622 km ultra-marathon is less likely to cause clinically significant hematologic changes in athletes.

• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.68-73
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• 2011

This study investigated, using the Orbscan II topography system, the influence of age and sex related changes on the corneal thickness and anterior corneal curvature, more specifically the fine structure of the cornea, in a Korean young population. The Orbscan II topography system is a computer-assisted slit-beam scanning technology that can map the anterior section of the cornea. The mean central corneal thickness of all subjects was $547.532{\pm}44.529\;{\mu}m$. There was no statistical difference (p>0.5) in the mean central corneal thickness between males and females. Sex and age related changes in the mean central corneal thickness had no specific statistical difference (P>0.5). There was a negative correlation between the anterior corneal curvature and the central corneal thickness in all subjects, except for the twenty year olds. However, the thickness relationship between the mean central corneal and the eight paracentral corneal thicknesses had strong statistical differences in all subjects. Also age and sex related changes in the central corneal thickness and the anterior corneal curvature in all subjects had no statistically significant difference, except from 20-26 years old (p>0.05). This information could be a suitable reference basis for future studies in the young population of Asia and for the development of examination tools for corneal refractive surgery.

• Radiation Oncology Journal
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• v.11 no.1
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• pp.109-117
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• 1993

To analyze biochemical changes of liver function following combined radiotherapy and hyperthermia, we reviewed retrospectively 37 patients with hepatocellular carcinoma treated with radiotherapy and hyperthermia between July 1988 and December 1990 at Department of Radiation Oncology, Yonsei University College of Medicine. Mean age was 52.7 years and male to female ratio was 11:1. The patients were classified as follows; to A and B group by Child's classification, to M and L group by irradiated volume, and subclassified into BM, BL, AM and AL group according to the combination of Child's classification and irradiated volume. Radiation dose to the primary tumor was 3060 cGy with daily 180 cGy, 5 fraction per week using 10 MV or 4 MV linear accelerator. Hyperthermia (Thermotron RF-8) was performed more than 4 times in all patients. Biochemical parameters including albumin (Alb), total bilirubin (T. Bil), aspartate aminotransferase (AST or SGOT), alanine aminotransferase (ALT or SGPT), and alkaline phosphatase (ALP) were regularly followed from 1 week before the treatment to 3 months after the treatment. The results are summerized as follows; 1) In all the patient, mean ALP level peaked at 1 month, decreased at 2 months, slightly increased at 3 months after the treatment. Mean SGOT and SGPT levels peaked at 1 month after the treatment. Mean T. Bil level increased continuously and highest at 3 months after the treatment. Mean Alb level did not show significant changes.; 2) Mean ALP level retured to normal level at 3 month after the treatment in A but increased in B group and the differences were statistically significant (p<0.01). Mean SGOT and SGPT levels peaked 1 month in A and 2 months after the treatment in B group. All the biochemical parameters did not show significant difference between M and L group. Mean ALP level increased at 3 months after the treatment in BM and BL groups and decreased in AM and AL groups. Mean SGOT level increased at 3 months after the treatment in BL groups.; 3) Hepatic failure occurred within 3 months after the treatment in 4 patients, all of whom were in BL group. It is suggested that pre-treatment liver function and irradiated volume influence biochemical changes of liver in patients with hepatocellular carcinoma following combined radiotherapy and hyperthermia, and this treatment modality appears generally to be safe but might cause hepatic failure particularly in patient with poor liver function and large treatment volume.

• Journal of Korean Biological Nursing Science
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• v.18 no.2
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• pp.94-101
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• 2016

Purpose: This study aimed to evaluate weight changes in women during the period of TAC (docetaxel-doxorubicin-cyclophosphamide) chemotherapy after breast surgery and the differences in weight changes by disease characteristics among Korean women with breast cancer. Methods: The design of this study was retrospective survey research. The subjects of this study were 130 patients with fully completed TAC chemotherapy between January 2012 and April 2015. Body weight before their operation, and at 3 weeks, 6 weeks, 9 weeks, 12 weeks, 15 weeks, and 18 weeks after surgery, as well as general and disease characteristics, were reviewed via their medical charts. Results: The mean age of the patients was 51.2 years. The preoperative (baseline) mean weight was $59.4{\pm}8.44$. Significant weight losses were observed in the initial (1st 3 week) period of TAC chemotherapy compared to the baseline and significant weight losses were observed with the exception of the period 6 weeks after breast surgery. There were significant differences in mean weight changes according to the stage of breast cancer, radiotherapy, and hormone therapy among disease characteristics. Conclusion: It is necessary to study weight changes after breast surgery for the long periods of TAC chemotherapy. Through the accumulated results of studies, nursing programs for breast cancer patients must be developed for the prevention of weight gain in the periods of TAC chemotherapy.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.5
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• pp.411-422
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• 2014

In this study, spatial and temporal variations of radiative forcing (RF) and mean temperature changes due to greenhouse gases ($CO_2$, $CH_4$, and $N_2O$) emitted from commercial aircraft were examined based on the simplified expression at the airports in Korea during 2009~2010. The radiative transfer model (SBDART) was used to compare with the RF and mean temperature changes calculated from the simplified expressions for greenhouse gas $CO_2$. The RF simulated by the SBDART was about 67% higher than that of the simplified expression, on average. The highest mean RF (up to $9.0mW/m^2$ for $CO_2$) and mean temperature changes (up to $9.7{\times}10^{-5}^{\circ}K/day$ for $CO_2$) for all GHGs occurred at Ulsan airport during the study period, whereas the lowest RF and temperature changes at Yangyang (for $CO_2$) and Sacheon airports (for $CH_4$ and $N_2O$). In the case of $CH_4$ and $N_2O$, their effects to the RF and mean temperature change were negligible compared to $CO_2$.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.3
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• pp.223-232
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• 2014

Monthly variations of radiative forcing (RF) and mean temperature changes by greenhouse gases emitted from commercial aircraft were estimated based on the simplified expression at four international airports (Incheon, Gimpo, Jeju, and Gimhae Airports) during the years of 2009~2010. The highest RF and mean temperature change in the study area occurred at Incheon Airport, whereas the lowest RF and mean temperature change at Gimhae Airport. During 2009~2010, the mean RF and mean temperature change estimated from aircraft $CO_2$ emissions at Incheon Airport were approximately 30.0 $mW/m^2$ and $0.022^{\circ}K$, respectively. The mean RF and mean temperature changes caused by other greenhouse gas $N_2O$ was significantly small (<<0.1 $mW/m^2$ and << $1{\times}10^{-3}^{\circ}K$). Meanwhile, $CH_4$ emissions caused negative mean RF ($-4.45{\times}10^{-3}mW/m^2$ at Incheon Airport) and the decrease of mean temperature ($-3.83{\times}10^{-6}^{\circ}K$) due to consumption of atmospheric $CH_4$ in the aircraft engine.