• Imaging Science in Dentistry
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• v.34 no.2
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• pp.69-74
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• 2004

Purpose : This study was conducted to compare the radiomorphometric indices of the mandible on panoramic radiographs among three groups of normal, osteopenia and osteoporosis and to determine whether panoramic indices have validity in predicting osteoporotic risk. Materials and Methods: Ninty-four postmenupausal women aged 42-72 years (mean 62±7.5) were examined using dual energy X-ray absorptionmetry (DEXA) of the lumbar and classified into three groups by WHO classification. Panoramic mandibular index (PMI), mandibular cortical thickness (Mental index (MI), Antegonial index (AI), Gonial index (G!)) and the mandibular cortical index (MCI) were measured bilaterally on panoramic radiographs and analyzed. Results: There were signigicant differences among normal, osteopenic and osteoporoti groups in PMI (I), PMI (S), MI, AI, GI and MCI. The sensitivities of the MCI (93%) and the combination index of MCI and MI (90%) in diagnosing osteopenic/osteoporotic cases were high. Conclusion: The widths and shapes of the mandibular cortical bone on panoramic radiography may highly reflect the systemic osteopenic/osteoporotic conditions of the patients.

• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.157-163
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• 2003

A systematic numerical experiment has been conducted to study droplet gasification in high pressure environments with pressure oscillations. The general frame of previous rigorous model[1] is retained but tailored for flash equilibrium calculation of vapor-liquid interfacial thermodynamics. Time-dependent conservation equations of mass, momentum, energy, and species concentrations are formulated in axisymmetric coordinate system for both the droplet interior and ambient gases. In addition, a unified property evaluation scheme based on the fundamental equation of state and empirical methods are used to find fluid thermophysical properties over the entire thermodynamic domain of interest. The governing equations with appropriate physical boundary conditions are numerically time integrated using an implicit finite-difference method with a dual time-stepping technique. A series of calculation have been carried out to investigate the gasification of an isolated n-pentane droplet in a nitrogen gas environment over a wide range of ambient pressures and frequencies. Results show that the mean pressures and frequencies of the ambient gas have strong influences on the characteristics of the droplet gasification. The amplitude of the response increases with increasing pressure, and the magnitude of the vaporization response increases with the frequency.

• Korean Journal of Adult Nursing
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• v.18 no.5
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• pp.790-797
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• 2006

Purpose: The purpose of this study was to investigate bone density and risk factors related to osteopenia to unmarried young adult women. Methods: The subjects consisted of 125 female college students. SPSS 12.0 program was used for the data analysis with t-test, ${\chi}^2-test$. The BMD of the calcaneus and body mass index (BMI) were measured with peripheral dual energy X-ray absorptionmetry. Other physical characteristics were measured with a scale and questionnaires. Results: The general characteristics of these people showed that the average age was 22.1 years old and that the average BMI was 20.8. The mean of BMD was normal, but 24.8% were osteopenia, 75.2% were normal. In the normal and osteopenia groups, there were significant differences in the status of the BMD according to age, height, weight, BMI, regular exercise, house chores, and the experiences of being on a diet. Conclusion: Women in their twenties had some osteoporosis risk, but they can change their BMD by doing regular exercise and by eating food to peak bone mass. For building peak bone mass, they need take exercise programs and education programs to prevent osteoporosis and follow-up care.

• Journal of Korean Academy of Nursing
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• v.30 no.1
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• pp.29-38
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• 2000

To determine whether personal history of lactation in premenopausal women influence bone mineral density, a cross-sectional study was conducted. One hundred eighty-four premenopausal women were selected from women who had been checked for bone mineral density by dual energy x-ray absortiometry in lumbar spine, femoral neck, Ward's triangle, and trochanteric site at general hospitals in Seoul and Pusan. They completed a questionnaire including life style factors and reproductive history. In the data analysis, Pearson correlation coefficients were used to test any association between individual variables and bone mineral density and a statistical comparisons between long term lactation(>24 months) and short term lactation(<24 months) were made by one way analysis of covariance. The results were summarized as follows: 1) There was no significant difference in the bone mineral density of the lumbar vertebrae in premenopausal women between the long term lactation group(>24months) and the short term lactation group(<24months). 2) There was no significant difference in the bone mineral density of the femur neck, Ward's triangle, and trochanteric site in premenopausal women between the long term lactation group (>24months) and the short term lactation group (<24months). Considering these results, we suggest prospective studies that measure bone mineral density before and after, in addition to those during lactation. We also suggest the further study with premenopausal women less than 35 who have achieved peak adult bone mass.

• Journal of the Korean Home Economics Association
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• v.29 no.3
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• pp.61-69
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• 1991

The relationships between nutrients intake, physical activity and bone mineral density were investigated in 19 elderly men aged 71-80 years. A trained nutritionist interviewed usual dietary intake and daily activity with a questionnaire, and bone mineral density was measured at the lumbar spine and three regions of the proximal femur (femur neck, Ward's triangle and trochanter) with a Luna DP3 dual photon absorptiometry. The correlations between dietary calcium intake and bone mineral density at the lumbar spine and trochanteric region were significant at P<0.05 and P<0.01 level respectively. the significant correlations were also found between vitamin A(P<0.005), riboflavin(P<0.01), and ascorbic acid(P<0.05) intake and bone mineral density at these sites. Higher physical activity was associated with greater bone mineral density of four sites, but this was not significant. But there were significant relationships between total energy expenditure and bone mineral density of the lumbar spine(P<0.01), femur neck (P<0.05) and Ward's triangle(P<0.05). In this study the results revealed that bone mineral density of the lumbar spine and trochanteric region were associated with dietary calcium intake. And bone mineral density of the femur neck and Ward's triangle were related to physical activity but not to nutrients intake. In conclusion, dietary calcium intake seems to be a important factor for greater bone mineral density. Further evidence will be needed that physical activity protects against bone fracture and osteoporosis in the edlerly.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.10-11
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• 2000

광통신을 이용한 근거리 전송과 장거리 전송에서 1.3 및 1.55 $mu extrm{m}$ 파장 영역의 빛이 사용되고 있다. 향후, 각 가정마다 광선로를 연결하는 Fiber-to-the-home (FTTH)의 개념과 광CATV가 발전함에 따라 1.3 및 1.55 $\mu\textrm{m}$ 빛을 검출하는 소자와 송신하는 소자가 필요하게 된다. 본 논문에서는 이러한 다중파장을 검출할 수 있는 집적소자를 제작 및 측정하였다. 본 논문에서 사용된 epitaxial layer의 구조는 N-InP 기판 위에 1 $\mu\textrm{m}$의 n-InP buffer층, 5층의InGaAs/InGaAsP 다중양자우물과 0.2 $\mu\textrm{m}$ InGaAsP separate confinement heterostructure (SCH) 층, 0.5$\mu\textrm{m}$ InP clad층과 0.1 $\mu\textrm{m}$ InGaAs cap 층으로 구성되어있다. 모든 epi 층은 InP 기판에 격자 정합이 되어있다. 다중양자우물구조는 84 $\AA$의 InGaAs 우물층과 100 $\AA$의 InGaAsP 장벽층으로 구성되며, 상온에서 0.787 eV (1.575 $\mu\textrm{m}$)의 bandgap energy를 갖도록 설계하였다. (중략)

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.181-184
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• 2003

Low Energy High flux Plasma Source인 Stationary Plasma thruster (SPT)를 이용하여 폴리이미드의 표면개질 후 접촉각과 표면에너지의 변화를 조사하고 접착력과의 관계를 조사하였다. 이온에너지는 180 eV - 200 eV, 이온전류 밀도는 수백 ${\mu}A/cm^2$, 이온선량은 $5\times10^{15}/cm^2$부터, $10\times^{18}/cm^2$로 $Ar^+,\;N_2^+,\;O_2^+$를 이온 주입시켰다. 표면 처리된 폴리이미드에 대한 접촉각 변화는 dual contact anglemeter로 증류수와 에틸렌글리콜을 이용하여 측정하였고, 표면에너지의 변화량을 구하였다. 접촉각의 변화는 아르곤 이온의 경우는 최저 $35^{\circ}$, 질소와 산소의 경우 $1\times10^{17}/cm^2$에서 각각 $14^{\circ},\;10^{\circ}$정도의 전촉각을 보였으며, $5\times10^{17}/cm^2$이상에서는 측정하기 불가능하였다. 산소 이온빔으로 처리된 PI의 표면을 x-ray photoelectron spectroscopy를 통하여 측정하여본 결과, 친수성기가 많이 형성되었음을 확인할 수 있었다. 접촉각 측정으르부터 PI의 표변에너지는 42.1 mN/m에서 아르곤 이온빔의 처리 시 65.2 mN/m로 산소 이온빔의 처리 시 81.2 mN/m로 각각 1.5배, 1.9배 정도 증대하였다. 산소 이온빔으로 처리된 PI 표면위에 스퍼터링으로 300 nm 정도의 clad layer 형성 후 $20{\mu}m$ 정도의 구리 전기 도금막을 형성하여, peel 강도를 측정한 결과 0.79 kg/cm의 강도를 얻을 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.30-33
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• 2004

Shallow p+-n junctions were formed by low-energy ion implantation and dual-step annealing processes The dopant implantation was performed into the crystalline substrates using $BF_2$ ions. The annealing was performed with a rapid thermal processor and a furnace. FA+RTA annealing sequence exhibited better junction characteristics than RTA+FA thermal cycle from the viewpoint of junction depth. A new simulator is designed to model boron diffusion in silicon, which is especially useful for analyzing the annealing process subsequent to ion implantation. The model which is used in this simulator takes into account nonequilibrium diffusion, reactions of point defects, and defect-dopant pairs considering their charge states, and the dopant inactivation by introducing a boron clustering reaction. Using a resonable parameter values, the simulator covers not only the equilibrium diffusion conditions but also the nonequilibrium post-implantation diffusion. Using initial conditions and boundary conditions, coupled diffusion equation is solved successfully. The simulator reproduced experimental data successfully.

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.33-38
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• 2011

The introduction of alternative fuels is beneficial to overcome the fuel shortage and reduce engine exhaust emissions. LPG and CNG are relatively clean fuel and considered as most promising alternative automotive fuels worldwide because of its emission reduction potential and lower fuel price compared to gasoline. Now a day’s adaptation of dual fuel approach is the growing as common trend. The two fuels can be successfully implemented with existing gasoline engine with little modification. The present study was done to analyze the performance and emissions analysis of a multi cylinder spark ignition engine fuelled with the benefits of CNG and LPG aseffective alternate automotive fuels by simply using them in an unmodified petrol engine. The test results indicate, the energy content of CNG and LPG is the most limiting factor in acceptance for fuel economy and performance reasons. Thermal efficiency was high for CNG lowest for gasoline and LPG between the two. BSFC, CO and HC were low and NOx was high for CNG and low for gasoline, LPG lies between the two.