• 한국분말재료학회지
• /
• 제18권6호
• /
• pp.575-582
• /
• 2011

MAO(Micro-Arc Oxidation) method was used to make $Al_2O_3$ surface on 6063 Al specimen. This study was focused on an influence of voltage, density of electrolyte and a period of treatment on the change of surface microstructure by using SEM(Scanning Electron Microscope), EDS(Energy Dispersive X-ray Spectroscopy). The microstructure shows higher roughness and thicker oxidized layer with increase of voltage and maintaining period of treatment. The density of electrolyte affected a formation of more dense surface and increase of a oxidized layer.

• 대한방사선기술학회지:방사선기술과학
• /
• 제12권1호
• /
• pp.25-29
• /
• 1989

This paper investigated on influence on the distinguishability of renal stone in the accordance with thickness of object, x-ray tube voltage and base density. In the relationship between object and renal stone shadow, object and tube voltage, the obtained results can be summarized as the following. 1. When thickness of object was thin, the distinguishability increased in base density $2.0{\sim}2.5$, but for adults was best shown in base density 1.5. 2. In the relationship between object and tube voltage, the distinguishability increased at lower tube voltages ($50{\sim}60\;kVp$), using grid. As mentioned above, it was thought that this method was very effective in describing the phenomena of renal stone in film density 1.5, tube voltages 60 kVp.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.2092-2094
• /
• 2000

As a next generation lithography (NGL) technology for VLSI semiconductor fabrication, electron beam, ion beam, X-ray and extreme ultraviolet(EUV) are considered as possible candidates. Among these methods, EUV lithography(EUVL) is thought to be the most probable because it is easily realized by improving current optical lithography technology. In order to set EUV radiation which can be applied to EUVL, it is essential to generate very high density and high temperature plasma stably. The method using a pulse power laser and a high voltage pulse discharge is commonly used to accomplish such a high density and high temperature plasma. In this paper we review the recent trends of the EUV generation technique by high density and high temperature plasma.

• 근관절건강학회지
• /
• 제18권1호
• /
• pp.5-15
• /
• 2011

Purpose: Osteoporosis is often considered as a women's disease, but men's osteoporosis is also increasingly recognized as an important public health problem. This study was carried out to identify the important modifiable risk factors for osteoporosis in men. Methods: Two hundred and fourteen men were selected among those who checked bone mineral density by dual energy x-ray absorptiometry in lumbar vertebrae from June to September, 2009 at 3 general hospitals in Busan. Self-administrated questionnaires and BMD results of lumbar vertebrae were used for data. Collected data were analyzed by using SPSS 14.0 program. Results: The sports activity level in 30's, body weight, and fracture history of mother were the most powerful influencing factors on the bone mineral density of lumbar vertebrae. Conclusion: These results highlight the need to participate vigorously in sports activity during 30s as a means of increasing peak bone mass in lumbar vertebrae in order to prevent osteoporosis and fracture in men.

• 한국멀티미디어학회논문지
• /
• 제19권8호
• /
• pp.1248-1259
• /
• 2016

Classification methods based on dual energy X-ray absorptiometry, ultrasonic waves, and quantitative computed tomography have been proposed. Also, a classification method based on machine learning with bone mineral density and structural indicators extracted from the CT images has been proposed. We propose a method which enhances the performance of existing classification method based on bone mineral density and structural indicators by extending structural indicators and using principal component analysis. Experimental result shows that the proposed method in this paper improves the correctness of osteoporosis classification 2.8% with extended structural indicators only and 4.8% with both extended structural indicators and principal component analysis. In addition, this paper proposes a method of automatic phantom analysis needed to convert the CT values to BMD values. While existing method requires manual operation to mark the bone region within the phantom, the proposed method detects the bone region automatically by detecting circles in the CT image. The proposed method and the existing method gave the same conversion formula for converting CT value to bone mineral density.

• 한국멀티미디어학회논문지
• /
• 제19권1호
• /
• pp.1-9
• /
• 2016

In this paper, we propose a method of measuring bone mineral density in a peripheral-type clinical X-ray CT using a phantom, and we propose a method of classifying osteoporosis using bone mineral density and bone structure parameters together. It segments the trabecular bone region and cortical bone region for the six sections of the phantom and calculates the average HU value of the segmented regions. By using these values, it derives an expression converting HU value to bone mineral density. It segments trabecular bone of 1 cm region in the end part of distal radius and extracts the bone mineral density and structural parameters for the trabecular bone region. We extracted bone mineral density and structural parameters for the 18 subjects each of normal and osteoporotic group. We carried out classification experiments using three classification methods; SAD, SVM, ANN. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value, likelihood ratio of the classification was improved in the order of ANN, SVM and SAD. Also, The sensitivity, specificity, accuracy, positive predictive value, negative predictive value, likelihood ratio of the classification was improved when we use the bone mineral density and structural parameters together.

• 대한간호학회지
• /
• 제30권1호
• /
• pp.29-38
• /
• 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.

• 보건교육건강증진학회지
• /
• 제15권1호
• /
• pp.179-194
• /
• 1998

This study focused on the body composition of Korean Basketball Players in Dual X -ray Absorptiometry. The principal subjects of this study were 10 Basketball Players who participated in the process of Dual Energy X -ray Absorptiometry at K.H. University Hospital for 8 months from Sept. 1. 1996 to April, 30. 1997. On the basis of the these measurements, the authors calculated physical indices and total fat percent. On the results of bone densitometry, the author analyzed body fat weight, body composition according to body position, bone mineral density and discerned the difference between the fatness which was calculated indirectly and which gained from the bone densitometry. 1. General Characteristics The mean age of the subjects was 20.4$\times$1.35 year. 2. Physical. Measurement The mean physical growth and development of the subjects were superior to standard value of the average Koreans 3. Body Fat by Physical Measurement Body surface area was 2.019$\times$0.111$m^2$, body volume was 74.4$\times$7.2$\ell$, body density was 1.041$\times$0.007$\ell$/kg, and body fat percent was 24.9$\times$2.9%. 4. Body Fat by Bone Densitometry Total body fat percent was 15.17$\times$2.19% and according to body position that of upper limb was 1.62%, that of lower limb was 5.55%, that of trunk was 7.06% and that of head was 1.05%. There was significant difference between the amounts of body fat from the methods used in this study; that from physical measurements and from bone densitometry method could be said most desirable. 5. Body composition According to Body Position Trunk was highest at 46.7%, lower limb was 36.0%, upper limb was 10.6%, and head was 6.7% in order. 6. Bone Mineral Content and Bone Density In bone mineral amount by body position, that of upper limb was 466.9$\times$46.4g, that of lower limb was 1,424.1$\times$154.0g, that of trunk was 1,343.0$\times$150.3g, and total bone mineral content was 3,786.8$\times$348.4g(4.78$\times$0.13%). Bone mineral density by body position, that of upper limb was 0.758$\times$0.072g/$\textrm{cm}^2$, that of lower limb was 1,342$\times$0.095g/$\textrm{cm}^2$, that of trunk was 1,169$\textrm{cm}^2$0.082g/$\textrm{cm}^2$, that of head was 1,742$\times$0.154g/$\textrm{cm}^2$ and total bone mineral density was 1,204$\times$0.077g/$\textrm{cm}^2$.

• Journal of the Korean Wood Science and Technology
• /
• 제34권3호
• /
• pp.1-7
• /
• 2006

국내에서 재배된 케나프의 해부 물리적 특성을 광학현미경, 주사전자현미경 및 X선회절법으로 조사하였다. 그 결과 케나프는 사부에 인피섬유, 사부 방사조직, 피층 유세포, 사관요소 등이 존재하였고, 목부는 도관요소, 목섬유, 방사조직 등으로 구성되어 있었다. 관공은 고립 및 2~3개가 방사방향으로 복합한 것이 많이 존재하였고, 방사조직은 평복, 방형, 직립세포가 모두 분포하고 있었다. 수피부의 인피섬유 길이는 생장기간이 길어짐에 따라 점차 증가하였고, 목부 섬유의 길이는 평균 0.74~0.82 mm로써 생장기간과 줄기의 높이에 관계없이 거의 차이가 없었다. 상대결정화도는 사부가 53~74%, 목부가 43~58%인 것으로 나타났으며, 셀룰로오스의 결정폭은 사부가 2.68~3.24 nm, 목부가 2.46~2.95 nm 정도인 것으로 나타났다. 케나프 줄기의 높이가 증가함에 따라 생재함수율과 생재밀도는 증가하였으나, 기본밀도는 낮게 나타났다.

• 치과방사선
• /
• 제25권1호
• /
• pp.51-70
• /
• 1995

The purpose of this investigation was to compare the direct digital radiographic system with film-based digital imaging system using Ektaspeed and Ektaspeed Plus film with respect to image characteristics and detectability and evaluate the sensor noise with the use of subtraction method. Direct digital radiographic system which used was Sens-A-Ray system(Regam Medical Systems, Sundsvall, Sweden) and film-based digital imaging system was composed of Macintosh II ci computer, high resolution Sony XC-77 CCD camera and intraoral x-ray film(Kodak Ektaspeed film, Kodak Ektaspeed Plus film). Images were taken by using CCD sensor of Sens-A-Ray system, Ektaspeed film and Ektaspeed Plus film with variable exposure time(0.06s, 0.1s, 0.16s, 0.2s, 0.3s, 0.4s, 0.5s, 0.6s, O.8s, LOs), 5 times at each exposure time. And then ektaspeed films and ektaspeed plus films were digitized using CCD camera. Image groups were divided into 3 groups; Sens-A-Ray group(direct digital radiographic system), Ektaspeed group and Ektaspeed Plus group (film-based digital imaging system) They were assessed by the following three aspects; image density, image contrast and detectability and sensor noise of Sens-A-Ray system was also evaluated. The results were as follow : 1. S group showed higher density than E , EP group except at the low exposure time(p<0.01). 2. S group showed higher contrast than E,EP group except at the high exposure time(p<0.01). 3. All groups showed good detectability at the each proper exposure time. Lowest exposure time which shows maximum detectability in S,EP group(0.5s) was lower than that in E group(0.6s). 4. Sensor noise of Sens-A-Ray system generally increased according to exposure time. On the basis of the above results, it was considered that Sens-A-Ray system could show higher speed, higher contrast than Ektaspeed, Ektaspeed Plus film except at too high and low exposure time and the same detectability as the conventional intraoral film.