• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.472-472
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• 2011

The capacitive coupled plasma (CCP) has been extensively used in the semiconductor industry because it has not only good uniformity, but also low electron temperature. But CCP source has some problems, such as difficulty in varying the ion bombardment energy separately, low plasma density, and high processing pressure, etc. In this reason, dual frequency CCP has been investigated with a separate substrate biasing to control the plasma parameters and to obtain high etch rate with high etch selectivity. Especially, in this study, we studied on the etching of $SiO_2$ by using the pulse-time modulation in the dual-frequency CCP source composed of 60 MHz/ 2 MHz rf power. By using the combination of high /low rf powers, the differences in the gas dissociation, plasma density, and etch characteristics were investigated. Also, as the size of the semiconductor device is decreased to nano-scale, the etching of contact hole which has nano-scale higher aspect ratio is required. For the nano-scale contact hole etching by using continuous plasma, several etch problems such as bowing, sidewall taper, twist, mask faceting, erosion, distortions etc. occurs. To resolve these problems, etching in low process pressure, more sidewall passivation by using fluorocarbon-based plasma with high carbon ratio, low temperature processing, charge effect breaking, power modulation are needed. Therefore, in this study, to resolve these problems, we used the pulse-time modulated dual-frequency CCP system. Pulse plasma is generated by periodical turning the RF power On and Off state. We measured the etch rate, etch selectivity and etch profile by using a step profilometer and SEM. Also the X-ray photoelectron spectroscopic analysis on the surfaces etched by different duty ratio conditions correlate with the results above.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.11.2-11.2
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• 2011

Polymer based organic photovoltaics have attracted a great deal of attention due to the potential cost-effectiveness of light-weight and flexible solar cells. However, most BHJ polymer solar cells are not thermally stable as subsequent exposure to heat drives further development of the morphology towards a state of macrophase separation in the micrometer scale. Here we would like to show three different approaches for developing new electroactive polymers to improve the thermal stability of the BHJ solar cells, which is a critical problem for the commercialization of these solar cells. For one of the examples, we report a new series of functionalized polythiophene (PT-x) copolymers for use in solution processed organic photovoltaics (OPVs). PT-x copolymers were synthesized from two different monomers, where the ratio of the monomers was carefully controlled to achieve a UV photo-crosslinkable layer while leaving the ${\pi}-{\pi}$ stacking feature of conjugated polymers unchanged. The crosslinking stabilizes PT-x/PCBM blend morphology preventing the macro phase separation between two components, which lead to OPVs with remarkably enhanced thermal stability. The drastic improvement in thermal stabilities is further characterized by microscopy as well as grazing incidence X-ray scattering (GIXS). In the second part of talk, we will discuss the use of block copolymers as active materials for WOLEDs in which phosphorescent emitter isolation can be achieved. We have exploited the use of triarylamine (TPA) oxadiazole (OXA) diblock copolymers (TPA-b-OXA), which have been used as host materials due to their high triplet energy and charge-transport properties enabling a balance of holes and electrons. Organization of phosphorescent domains in TPA-b-OXA block copolymers is demonstrated to yield dual emission for white electroluminescence. Our approach minimizes energy transfer between two colored species by site isolation through morphology control, allowing higher loading concentration of red emitters with improved device performance. Furthermore, by varying the molecular weight of TPA-b-OXA and the ratio of blue to red emitters, we have investigated the effect of domain spacing on the electroluminescence spectrum and device performance.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.15 no.1
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• pp.53-59
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• 2008

Purpose: The purpose of this study was to examine the effects of treadmill walking exercise on the BMD (Bone Mineral Density) and BMI (Body Mass Index) of middle-aged women in their forties. Method: A nonequivalent control group pretest-posttest design was used for this study. The experiment was conducted for 10 weeks from May 17 to July 25, 2004 with 29 middle-aged women in their forties, who were assigned to a walking exercise group (16) or a control group (13). The experimental group had not exercised regularly before participating in this program. The control group received no exercise treatment during the research period. The BMD and BMI were measured with peripheral dual energy x-ray absorptiometry and bioelectrical impidence analysis, respectively. $X^2-test$ and Mann-Whitney U test with the SPSS version 11.0 program were used to analyze the data. Result: Treadmill walking exercise was effective for middle-aged women in increasing BMD and decreasing BMI. Conclusion: The findings of this study indicate a need to develop walking exercise protocols for middle-aged women to help them achieve a healthy life.

• Journal of Korean Academy of Nursing
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• v.34 no.5
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• pp.760-770
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• 2004

Purpose: This study was done to identify the effects of weight-bearing exercise(WBE) on bone metabolism. Method: WBE was performed for 12 weeks by healthy college women. Bone-related parameters were measured four times during this period by evaluating the immunoradiometric assay and enzyme immunoassay. Bone mineral densities(BMDs) were measured by dual energy x-ray absorptiometry before and after the WBE program. Data was analyzed using t-test, paired t-test, $x^2$-test, and repeated measures ANOVA. Result: Osteocalcin, a bone formation marker, increased more in the experimental group than in the control group based on the interaction between time and group(F=3.29 p=.024). Little difference between the two groups was found for the other parameters: urinary deoxypyridinoline, insulin-like growth factorI, parathormone, serum calcium, and serum phosphorus without showing any time interaction between the groups. The femoral trochanter BMD rose in the experimental group while that of the control group fell, showing a significant difference for BMD(t=3.06 p=.005). However, there was no significant difference between the two groups for changes in BMD of the forearm, lumbar spine, femoral neck, and femoral ward's triangle. Conclusion: These findings supported the WBE is beneficial for increasing bone formation in college women and long-term application is needed to substantiate the effects of WBE as a intervention in promotion of bone-health.

• Journal of radiological science and technology
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• v.35 no.1
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• pp.1-7
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• 2012

Dual Energy X-ray Absorptiometry(DEXA) is commonly used to diagnose Osteoporosis. The errors of DEXA bone density operation are caused by operator, bone mineral density meter, blood testing, patient. We focus on operator error then study about how much influence operator's region of intest(ROI) in bone testing result. During from March to July in 2011. 50 patients ware selected respectively from 30, 40, 50, 60, and 70 age groups who came to Korea University Medical Center(KUMC) for their Osteoporosis treatment. A-test was performed with usually ROI and B-test was performed with most widely ROI. Then, We compare A-test and B-test for find maximum difference of T-score error which occurred operator ROI controlling. Standard deviation of T-score of B-test showed 0.1 higher then A-test in femur neck. Standard deviation of B-test showed 0.2 higher then A-test in Ward's area which in Greater trocanter and Inter trocanter. Standard deviation of B-test showed 0,1 lower then A-test in L-1. Bone density testing about Two hundred patients results are as follow. When operator ROI was changed wider than normal ROI, bone density of femur was measured more higher but bone density of L-spine was measured more lower then normal bone density. That means, sometime DEXA bone density testing result is dependent by operator ROI controlling. This is relevant with the patient's medicine and health insurance, thus, tester always keep the size of ROI for to prevent any problem in the patient.

• Clinical and Experimental Pediatrics
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• v.48 no.8
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• pp.857-864
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• 2005

Purpose : The objectives of this study was to evaluate the correlations between the indices of insulin sensitivity using fasting glucose and insulin level, and the body fat mass measured by bioelectrical impedance analysis(BIA) and dual energy X-ray absorptiometry(DEXA), and to determine the clinical usefulness of insulin sensitivity indices when obese children were followed up. Methods : In this study, 28 simple obese children and adolescents were included. Anthropometric data including body weight, height, obesity degree(OD), body mass index(BMI), and waist-to-hip ratio were collected and then body fat mass was measured by using BIA and DEXA. For metabolic data, 12 hour fasting serum glucose, insulin and lipid profiles were measured and indices for insulin sensitivity(G/I ratio, $log_{insulin}$, HOMA-IR, $log_{HOMA-IR}$, QUICKI) were calculated. Results : BMI had a higher correlation with insulin sensitivity indices than OD(G/I ratio, -0.463 vs -0.209; $log_{insulin}$, 0.417 vs 0.196; HOMA-IR, 0.301 vs 0.238; $log_{HOMA-IR}$, 0.403 vs 0.198; QUICKI, -0.451 vs -0.224). But OD had a higher correlation with body fat mass measured by BIA and DEXA than BMI(BIA, 0.612 vs 0.316; DEXA, 0.667 vs 0.512). The G/I ratio was correlated with body fat mass in BIA(r=-0.420, P<0.05) and DEXA(r=-0.512, P<0.01), percentage of body fat(percentage of fat) in BIA(r=-0.366, P<0.05) and DEXA(r=-0.449, P<0.01). HOMA-IR was only correlated with body fat mass in DEXA(r=0.341, P<0.05). Conclusion : This study revealed that G/I ratios had a statistically significant correlation with anthropometric obesity indices(OD and BMI) and also had a correlation with both body fat mass and percentage of fat. These results suggest that G/I ratios could be used as useful index when obese children and adolescence are followed up.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.228-235
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• 2009

As we recognize the health care, test of BMD is increased. There are various methods in BMD, Dual Energy X-ray absorptiometry (DEXA) which has high precision and accuracy, and low medical exposure dose has been widely used. To measure the changes of BMD, the test must be done as same posture at first and follow up study performed a year. we analyze the difference in the hour taken before and after the examination by radiologic technologist, frequency of scout scan, and the amount of the radiation exposure. The hour of the examination and frequency of the scout scan were shorten and the dose of the radiation exposure is reduced. As the numerical value of total subjects is converted into that of one person, the duration for the test was 52 seconds, the frequency for the scout scan 0.79 time, and the dose for the radiation exposure $13{\mu}Sv$. When the health care provider perform the precise and easy methods to minimize changes of posture and the skillful ability to manage the test, useless radiation is decreased.

• Journal of the East Asian Society of Dietary Life
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• v.5 no.1
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• pp.41-51
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• 1995

Bone mass accretion during puberty appears to be critical in the development of peak bone mass. Although bone density of females in Korea has been studied, only a few studies have related bone mass with anthropometric patterns or puberty in the pubescent girls. This study was conducted as part of a study of major determinants of bone development during puberty. Subjects were aged 14∼16 yr(mean 14.97), and had no history of disorders or dedication use likely to influence bone or calcium metabolism. Bone mineral density and content were measured by dual energy X-ray absorptiometry using a Lunar DPX+Scanner (Lunar Madison, WI). Also, total body fat, and total lean body mass were assessed using a Lunar DPX dual-energy X-ray absorptiometer, Pubertal status was assessed according to the Marshall and Tanner guidelines. Serum levels of osteocalcin was measured by RIA using a commercial kit assay. Skinfold measurements were taken with a skinfold caliper(Lange Caliper, USA). Data were analyzed using the regression and GLM procedure of the statistical package SAS. The results indicated that the observed means for lumbar spine BMD and femoral BMD correspond to approximately 91% and 96% of the means for young adult females, respec tively. All subjects were menarchal, with the majority being in the middle to end stages of pubertal development. Total body BMD was positively related to fat mass(P<0.001), lean body mass and time since menarche, and negatively related to urine pyridinoline, serum alkaline phosphatase and osteocalcin. The data indicate that girls who reported lower age for menarche had significantly higher bone densities than girls who reported higher age for menarche. Attaining peak skeletal bone mass during puberty may reduce the incidence of osteoporosis in later life. this finding suggests that early menarche may augment peak bone mass, influencing the extent of bone loss later in adulthood. The results suggest that good nutrition in childhood appears to be needed not for growth and development, but possibly also to assure an optimal peak of bone mass and thus greater latitude for the maintenance or skeletal integrity in the face of bone losses. Troeps skinfold thickness was a better predictor of total BMD and total BMC than was any other skinfold thickness. The study did not find a relationship between total BMD and body fat %, but total fat was significantly positively related to total BMD(r=0.49) and total BMC(r=0.60). It supports earlier report that there was a significant correlation between TBMD and body weight. Conclusively, total fat, lean body mass and pubertal development could influence BMD in pubescent girls. Clearly, longitudinal studies are required to assess the effect of puberty on peak bone mass, and to define further the potential determinants of peak bone mass.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.3
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• pp.265-273
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• 2000

Purpose : The aim of this study was to evaluate the bone mineral density of iliac and tibial bone which are frequently selected as autogenic bone graft donor sites, and to evaluate the efficiency of this method as a guideline for the selection of bone graft donor site. Materials and Methods : In this study 61 male and 70 female volunteers at Chungbuk National University Hospital were involved between Jan. 1998 to Sept. 1999. We measured bone mineral density of the iliac and the tibial bone using dual energy X-ray absorptiometry. We evaluated the data using the SAS system for Windows and bone mineral density of the lumbar was used for control. Results : Age showed the highest correlation in correlation matrix between physical and bone variables. Height and weight showed lower correlation of linear increment. In man, the change of bone density according to age demonstrated linear decrease irrespective of the lumbar, ilium, and tibia. In woman, the change of bone density according to age showed cubic form, which increased in the third and forth decade. So it had a peak bone mass on about 35 year-old, thereafter, the change of bone density slowly decreased until 50 year-old, but it rapidly decreased after 50 year-old and it slowly decreased again after 65 year-old. Both in all subjects and subject with osteoporosis, the change of bone mineral density according to age showed statistically significant decrease in lumbar and tibia, but ilium was irrespective. Conclusion : In patients of aged or with osteoporosis, ilium demonstrated less tendency of decrease in bone mineral density than tibia. So this preliminary study suggested that ilium seemed better donor site for autogenic bone graft than tibia.

• Journal of Radiation Industry
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• v.12 no.4
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• pp.311-316
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• 2018

Average life expectancy is getting longer due to medical developments and improvements in living standards. So much so that the elderly have an increased risk of developing osteoporosis. Therefore, it is important to prevent, diagnose, and treat the senile disease at an early stage through a bone density test. Bone density is measured by dual energy X-ray absorption (DXA). In this study, while using DXA, in cases when the measurements for both the lumbar and the femur could not be taken simultaneously, the correlation between both measurements were known, and the measurement of one area was used to make a clinical inference for the value of the other. Measurements were taken using Lunar Prodigy Advance (GE) for 43 participant with clinically significant fractures. Statistical calculations were produced and analysed regarding bone density. In case of T-score, lumbar spine produced a statistical result of $-2.112{\pm}1.836$ and femur neck was $-1.716{\pm}1.565$. In case of Z-score lumbar spine produced a statistical result of $-0.151{\pm}1.513$, and femur neck $-0.026{\pm}1.283$. It is indicated that the pearson correlation coefficient of T-score between lumbar spine and femur neck is high at 0.699, and the pearson correlation coefficient of Z-score is considered relatively high at 0.503. The correlation of bone density between lumbar spine and femur neck is shown to be statistically meaningful in T-score's p-value at 0.000 and Z-score's p-value at 0.001. In conclusion, it seems to have clinical usefulness that we can infer the result of one measurement through that of the other part tested, based on the knowledge of the correlation coefficients between lumbar spine and femur neck.