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This study was performed for the purpose of the physical and mechanical properties of Rhyolite, Andesite, Granite-gneiss, Quartz-porphyry, in Deogon mine. The main results obtained were as follows ; (1) The angle of internal friction and the brittleness of samples were proportioned to the ratio of compressive strength to Brazillian tensile strength. (2) The shear strength by the equation (3-3-2) was nearly equal to that on the common tangent line of Mohr's circle. (3) The stress-volumetric strain curves of all samples were divided into three stages ; the preexisting cracks were clossed at the first stage(Ⅰ), the linear elastic deformation occurred because of frictional sliding on crack face at the second stage (Ⅱ), the micro-crack was started in the sample at the third stage (Ⅲ). and the lateral strain was greater that the axial strain at the failure stage of the sample. (4) The lowering ratio of Brazilian tensile strength for dry state and saturation state of samples were high in the following order ; Quartz-porphyry, Andesite, Rhyolite, Granite-gneiss. (5) The normal stress acting on failure plane was proportioned to the compressive strength. (6) The store energy was proportioned to the strain energy.
Granites contain many micro-defects which oriented preferentially along with the direction of three crossed surface such as rift plane, grain plane and hardway plane. These micro-defects affect on the physical properties of the granite. Quarryman use the micro-defects structure which is called "Kyeol" in quarring the granite. However, this method is not established neither scientifically nor theoretically. Therefore, this study was performed to establish basic theory of the granite quarring from empirical function of the quarryman. For this purpose, the granite is sampled from Iksan(Hamyeol) and Jinan(Yongdam). In the three directions of "Kyeol", p-wave velocity(Vp) and tensile strength (σt) was measured every ten degree in the diametric direction and the preferred orientation of micro-defects was observed through the poralized microscope with the thin section. The results are summerized as follows. 1) P-wave velocity and tensile strength of rift plane, grain plane and hardway plane while there was a diference to some degree indicates in order of R. G and H plane commonly, and show the harmony vibration of the 180° cycle. 2) Three dimensional Vp and σt presume in the form of anisotropy cross at right angles. 3) In the observation of defect structure, cracks which grow parallel to each plane were confirmed. Depend on the degree of these cracks anisotropy of granite recognized.
In this paper an experimental study of the effect of flame on granite spalling was described. Flame of oxygen and acethylene was moved along the rock surface. The results of flame on granite spalling were as follows. ① Many flakes or spalls of the rock were broken off the rock surface. ② The optimum distance between the burner and the rock surface was founded out. ③ Surface velocity of flame across the rock was an important factor in determining rock spalling rate ④ The depth of spall increased with the thermal energy applied.
There has been a rapid increase of interest to unconventional methods of rock fracturing. Particularly, mechanics of thermal fracture, either by the application of direct heat or electrothermal conversion, are most favourable for practice. The thermal fracturing rock is a quite effective method for hard granite type rocks. Many studies about thermal fracturing of rock have been made, while the texture changes of rocks in high temperature have not been studied till today. the author observed the texture changes of rocks heated to high temperature, and the results obtained in the experiments are presented and discussed.
The authors have a summarized of the characteristics of underground diesel equipments that are widely used today. The authors have a summarized of the characteristics of underground diesel equipments that are widely used today. 1. The recent rapid increase in the use of diesels underground has been the result of three important advantages offered by diesel power safety, flexibility and economy. 2. The diesel exhaust is cleaner than an automobile in terms of toxic gases. Fumes from explosives used in mining methods can be several times more dagerous than diesel exchaust. 3. It is clear that all the gaseous pollutants in a diesel engine exhaust can be diluted to well within safe exposure limits by a relatively low ventilating air current. 4. Practical experience and currently available medical data indicate there is no significant hazard associated with the gaseous toxicants. 5. A Permissible diesel can operate quite safely in relatively high concentration of methane gas than any other piece of mobile machinery currently used in gassy coal mines. 6. The safety features in most current equipment make diesels even safer than in the past and statics shows diesel have been safer that electrical equipment. 7. The combination of catalytic scrubber and new cyclonic water scrubber in series will go a long way in reducing the potential hazards associated with the carbon monoxide, unburned hydro-carbons and particulate matter in diesel exhausts. 8. The Bureau of Mines and MESA continue to collect date relevant to the use of diesels undergrouds, so more precise information on ventilation requirements and operational procedures can be developed. It should be possible to introduce suitable regulations to govern the construction and operation of diesel equipment underground.
An investigation into the effect of liquids (water, glycerine, ethylene glycol, nitrobenzene, ethyl alcohol, benzaldehyde, and n-butyl alcohol) on the uniaxial compressive strength and the strain measurment of Chun-ho Mt. limestone was made. The main results are as follows : 1. The uniaxial strength of the test pieces represents the largest value when the test piece is dry and the smallest when it is saturated with water. 2. Experimental evidence suggests that as the dielectric constant and surface tension of the liquid increases, the compressive strength and the strain of limestone decreases
In order to examine whether or not we could apply the Hardgrove index to the Korean anthracite we measured the Hardgrove grindability index of coals whose samples were gathered from each colliery extensively. Each coal sample was grinded with Hardgrove grindability machine. The specific surface area of coal samples was calculated from equivalent number of surface area with paricle distribution. In addition, we also investigated relation between the grindability and fixed carbon contents, ash contests. The results are summarized as follows. ①The grindability index of coal samples was widely distributed with 46.33~248.48 larger than that(50~120) of general foreign ones. ②The formula of the Hardgrove grindability index, H.G.I is 6.93W+13. According to the formula of the grindability index obtained by the experiment, G.I is 6.98W+13.8. ③When the grindability index range from 50 to 220 the difference of the grindability index caculated with the formula obtained by the experiment and the formula of Hardgrove index is +1.26%~-0.18%. ④There is no correlation between the fixed carbon content, the ash content and the grindability index of total samples. But there is some correlation between the above and each coalfield and colliery.
서론: 감염성 심내막염 환자에서 폐동맥판막을 단독으로 침범하는 경우는 매우 드물어 감염성 심내막염 환자 중 1.5% 미만에서 발생하는 것으로 알려져 있다. 저자들은 내원 10일 전 위,대장 내시경을 시행 받은 혈액 투석 중인 만성 콩팥병 환자가 호흡곤란을 주소로 입원 후 검사한 심초음파에서 폐동맥 판막의 vegetation이 발견되었고 혈액배양검사에서 Enterococcus faecalis가 배양되어 항생제 치료 후 증상 호전 보여 퇴원한 1례가 있어 보고한다. 증례: Chief Complain 61세 남자 환자가 약 3개월간 지속된 호흡곤란, 기침, 가래 증상으로 입원하였다. -Past medical history: 10년 전 한약 복용 후 갑자기 콩팥기능이 저하되어 혈액 투석을 시작하여 10년 동안 혈액 투석을 받고 있다. -Initial finding 입원 시 체온은 36.5℃, 혈압은 90/60 mmHg, 맥박은 80회/분, 호흡수는 26회/분이었다. 혈액검사에서 C-reactive protein 10.89 mg/dL과 erythrocyte sedimentation rate 120 mm/hr로 증가된 것 외에는 정상소견을 보여주었다. 진단/치료: 심초음파에서 우심방과 우심실의 확장소견과 폐동맥 판막에 국한된 3.5 × 0.9 cm의 vegetation으로 의심되는 덩어리가 관찰되었다. 혈액 배양검사에서 Enterococcus faecalis가 3회에 걸쳐서 배양되었다. 심초음파 소견과 혈액 배양검사 결과에 따라 심내막염을 진단하고, 내원일부터 경험적으로 세프트리악손과 반코마이신을 투여하였으며 내원 5일 후부터 혈액배양검사 결과에 맞추어 반코마이신과 겐타마이신으로 바꾸어 치료하였다. 항생제 투여 후 혈액검사와 발열 호전되는 양상 보이고 입원치료 4주 후에 시행한 추적 심초음파에서 vegetation은 1.2 × 0.7 cm으로 감소된 소견을 보여 퇴원 후 외래 추적관찰 하였다.
In oredr to obtain sone data of the thermal rock fracture, the author measured the strength changes of racks heated to high emperature. In this paper the author described the experimental results about two kinds of such typical rocks as granite and limestone, the results are as follows; 1) The strength in instant cooling in water from hot conditions is less than that in gradual cooling in a furnace. 2) Fracturing mechanism of granite is transformation of crystal form of the constituting minerals of rock and that of limestone is decomposition of the constituting minerals.