Literature review on fractography of dental ceramics (치과용 세라믹의 파단면분석(fractography)에 대한 문헌고찰)
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- Journal of Dental Rehabilitation and Applied Science
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- v.38 no.3
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- pp.138-149
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- 2022
The clinical applicability of ceramics can be increased by analyzing the causes of fractures after fracture testing of dental ceramics. Fractography to analyze the cause of fracture of dental ceramics is being widely applied with the development of imaging technologies such as scanning electron microscopy. Setting the experimental conditions is important for accurate interpretation. The fractured specimens should be stored and cleaned to avoid contamination, and metal pretreatment is required for better observation. Depending on the type of fracture, there are dimple rupture, cleavage, and decohesive rupture mainly observed in metals, and fatigue fractures and conchoidal fractures observed in ceramics. In order to reproduce fatigue fracture in the laboratory, which is the main cause of fracture of ceramics, a dynamic loading for observing slow crack growth is essential, and the load conditions and number of loads must be appropriately set. A typical characteristic of a fracture surface of ceramic is a hackle, and the causes of fracture vary depending on the shape of hackle. Fractography is a useful method for in-depth understanding of fractures of dental ceramics, so it is necessary to follow the exact experimental procedure and interpret the results with caution.
This study was conducted to derive an Instantaneous Unit Hydrograph for the accurate and reliable unitgraph which can be used to the estimation and control of flood for the development of agricultural water resources and rational design of hydraulic structures. Eight small watersheds were selected as studying basins from Han, Geum, Nakdong, Yeongsan and Inchon River systems which may be considered as a main river systems in Korea. The area of small watersheds are within the range of 85 to 470
Purpose: To evaluate kidney function, renal relative uptake is very important and is affected by kidney and the setting of background region of interest (ROI). In particular, in the case of patients with hydronephrosis to the naked eyes, such as size, position and shape etc. can be difficult to identify. So according to ROI to be set by user, the results are many differences. This study assumes the ROI of a constant kidney. According to the change of background ROI by analyzing renal relative uptake affect how the results are intended to study. Materials and Methods: From January 2012 to February 2013, we analyzed 27 patients with hydronephrosis who were examined MAG3 test in nuclear medicine department of Samsung medical center. After patients were received intravenous injection of
An accurate measurement of size, surface area and volume of agricultural products is essential in many engineering operations such as handling and sorting, and in heat transfer studies on heating and cooling processes. Little information is available on these properties due to their irregular shape, and moreover very little information on the rough rice, soybean, barley, and wheat has been published. Physical dimensions of grain, such as length, width, thickness, surface area, and volume vary according to the variety, environmental conditions, temperature, and moisture content. Especially, recent research has emphasized on the variation of these properties with the important factors such as moisture content. The objectives of this study were to determine physical dimensions such as length, width and thickness, surface area and volume of the rough rice, soybean, barley, and wheat as a function of moisture content, to investigate the effect of moisture content on the properties, and to develop exponential equations to predict the surface area and the volume of the grains as a function of physical dimensions. The varieties of the rough rice used in this study were Akibare, Milyang 15, Seomjin, Samkang, Chilseong, and Yongmun, as a soybean sample Jangyeobkong and Hwangkeumkong, as a barley sample Olbori and Salbori, and as a wheat sample Eunpa and Guru were selected, respectively. The physical properties of the grain samples were determined at four levels of moisture content and ten or fifteen replications were run at each moisture content level and each variety. The results of this study are summarized as follows; 1. In comparison of the surface area and the volume of the 0.0375m diameter-sphere measured in this study with the calculated values by the formula the percent error between them showed least values of 0.65% and 0.77% at the rotational degree interval of 15 degree respectively. 2. The statistical test(t-test) results of the physical properties between the types of rough rice, and between the varieties of soybean and wheat indicated that there were significant difference at the 5% level between them. 3. The physical dimensions varied linearly with the moisture content, and the ratios of length to thickness (L/T) and of width to thickness (W/T) in rough rice decreased with increase of moisture content, while increased in soybean, but uniform tendency of the ratios in barley and wheat was not shown. In all of the sample grains except Olbori, sphericity decreased with increase of moisture content. 4. Over the experimental moisture levels, the surface area and the volume were in the ranges of about
The following conclusions are induced from a study on the acupuncture therapy depending on hyungsang of the persons. The study is made on the basis of 'Internal classic (內經)& and &Clinical Lectures by Dr. Jeesan&. The acupuncture originated from the treatment of spasm with numbness in the southern area. The acupuncture is basically a remedy for the exterior disease of meridian but also it can be a cure for the interior disease of Jang and obstinate disease with accurate method. Three mechanisms of acupuncture are described in 'Internal classic'. The first is to make meridian circulate smoothly. The second is to regulate Ki and Hyul. The third is to regulate points through which the meridian-Ki goes in and out smoothly or adversely. There are two ways of acupuncture in 'Internal classic'. One is based on pulse and symptom and the other on the Hyungsang. The former is more generally used therapy, to which depletion method, Asi point method(阿是穴 療法), Inyoung-kigu pulse comparison method (人迎氣口脈法) and method depending on jang-bu disease belong. Acupuncture is done on Su points(輸穴) and back-su point(背兪穴) in case of jang-disease. In case of bu-disease, the treatment is done on Hap points(合穴) and Mo-points(募穴). The latter includes two methods; one according to invariable Hyungsang. And the other to variable Hyungsang. The method of acupuncture according to invariable Hyungsang usually selects Won-points(原穴). Different Hyungsang requires different method of acupuncture; In case of Dam type, the acupuncture is mainly practiced on four-Kwan points with reinforcing and reducing methods achieved by the direction of the needle tip pointing to. In case of Bangkwang type, the acupuncture is usually done on Jungwan(中脘) and Poongyung(豊隆) with reinforcing and reducing methods by means of respiration. In case of female, more effective are the acupoints on the right and lateral parts of the body selected on the basis of five su-points of the twelve meridians matching the heavenly stems and earthly branches. In case of male, more effective are the acupoints on the left, front and rear parts of the eight extra meridians. In case of acupuncture to the person with Hyungsang of five jang and six bu, each person's intrinsic Hyung, color, pulse, must be observed. Because symptoms of jang-bu disease also must be checked up. Acupuncture is done on the Won-points of the meridians related to the jang and bu where the disease starts. The disease of five jang is so obstinate that it requires both of medication and acupuncture for a long time. In case of acupuncture to the person with Hyungsang of animal types, diagnosis is made on the basis of shape, temper, function and color. And the treatment is given on the Won-points of corresponding exterior and interior meridians. For the fish type, the acupuncture is done on the kidney meridian of foot-soyin and the urinary bladder of foot-taiyang. For the bird type, on the heart meridian of hand-soyin, the pericardium meridian of hand-gualyin, and the small intestine meridian of hand-taiyang For the deer type, on the liver meridian of foot-gualyin and the gallbladder meridian of foot-soyang. For the turtle type, on the lung meridian of hand-taiyin and the large intestine meridian of hand-yangmyung.
It is widely accepted that the shape and structure of bone are closely related to the activity of attached muscle. Numerous clinical and animal experimental studies indicated the significant effects of masticatory muscle function on maxillofacial morphology. Recently, the development of ultrasonography has spread throughout different fields of medicine. In the clinical examinations, ultrasonography is a convenient, inexpensive technique to apply with accurate and reliable results. The aim of this study is to assess the thickness of the masseter muscle and its correlation to maxillofacial skeleton by examining 35 male and 15 female dental students at Kangnung National University. The masseter muscle thickness of the subjects were measured by ultrasonographic scanning with a 7.5MHz linear probe, and their maxillofacial morphology were investigated by lateral cephalometric radiographs. The relationship between the masseter muscle thickness and maxillofacial morphology of normal adult was statistically analyzed, and the following results were obtained. 1. The average thickness of male masseter muscle was 13.8
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70