• Economic and Environmental Geology
• /
• v.5 no.4
• /
• pp.187-209
• /
• 1972

Drilling position is one of the most important factors affecting on the blasting effects. There has been many reports on several blasting factors of burn-cut by Messrs. Brown and Cook, but in this study the author tried to compare drilling positions of burn-cut to pyramid-cut, and also to correlate burn-cut effects of drilling patterns, not being dealt by Prof. Ito in his theory, which emphasized on dynamical stress analysis between explosion and free face. According to former theories, there break out additional tensile stress reflected at the free face supplemented to primary compressive stress on the blasting with one-free-face. But with these experimented new drilling patterns of burn-cut, more free faces and nearer distance of each drilling holes make blasting effects greater than any other methods. To promote the above explosive effect rationary, it has to be considered two important categories under-mentioned. First, unloaded hole in the key holes should be drilled in wider diameter possibly so that it breaks out greater stress relief. Second, key holes possibly should have closer distances each other to result clean blasting. These two important factors derived from experiments with, theories of that the larger the dia of the unloaded hole, it can be allowed wider secondary free faces and closes distances of each holes make more developed stress relief, between loaded and unloaded holes. It was suggested that most ideal distance between holes is about 4 clearance in U. S. A., but the author, according to the experiments, it results that the less distance allow, the more effective blasting with increased broken rock volume and longer drifted length can be accomplished. Developed large hole burn-cut method aimed to increase drifting length technically under the above considerations, and progressive success resulted to achieve maximum 7 blasting cycles per day with 3.1m drifting length per cycle. This achievement originated high-speed-drifting works, and it was also proven that application of Metallic AN-FO on large hole burn-cut method overcomes resistance of one-free-face. AN-FO which was favored with low price and safety handling is the mixture of the fertilizer or industrial Ammonium-Nitrate and fuel oil, and it is also experienced that it shows insensible property before the initiation, but once it is initiated by the booster, it has equal explosive power of Ammonium Nitrate Explosives (ANE). There was many reports about AN-FO. On AN-FO mixing ratio, according to these experiments, prowdered AN-FO, 93.5 : 6.5 and prilled AN-FO 94 : 6, are the best ratios. Detonation, shock, and friction sensities are all more insensitive than any other explosives. Residual gas is not toxic, too. On initation and propagation of the detonation test, prilled AN-FO is more effective than powered AN-FO. AN-FO has the best explosion power at 7 days elapsed after it has mixed. While AN-FO was used at open pit in past years prior to other conditions, the author developed new improved explosives, Metallic AN-FO and Underwater explosive, based on the experiments of these fundmental characteristics by study on its usage utilizing AN-FO. Metallic AN-FO is the mixture of AN-FO and Al, Fe-Si powder, and Underwater explosive is made from usual explosive and AN-FO. The explanations about them are described in the other paper. In this study, it is confirmed that the blasting effects of utilizing AN-FO explosives are very good.

• Journal of Chest Surgery
• /
• v.35 no.6
• /
• pp.420-429
• /
• 2002

Moderate hypothermic cardiopulmonary bypass (CPB) has commonly been used in cardiac surgery. Several cardiac centers recently practice normothermic CPB in cardiac surgery, However, the clinical effect and safety of normothermic CPB on cerebral metabolism are not established and not fully understood. This study was prospectively designed to evaluate the clinical influence of normothermic CPB on brain metabolism and to compare it with that of moderate hypothermic CPB. Material and Method: Thirty-six adult patients scheduled for elective cardiac surgery were randomized to receive normothermic (nasopharyngeal temperature ＞34.5 $^{\circ}C$, n=18) or hypothermic (nasopharyngeal temperature 29~3$0^{\circ}C$, n=18) CPB with nonpulsatile pump. Middle cerebral artery blood flow velocity (VMCA), cerebral arteriovenous oxygen content difference (CAVO$_{2}$), cerebral oxygen extraction (COE), modified cerebral metabolic rate for oxygen (MCMRO$_{2}$), cerebral oxygen transport (TEO$_{2}$), cerebral venous desaturation (oxygen saturation in internal jugular bulb blood$\leq$50 %), and arterial and internal jugular bulb blood gas analysis were measured during six phases of the operation： Pre-CPB (control), CPB-10 min, Rewarm-1 (nasopharyngeal temperature 34 $^{\circ}C$ in the hypothermic group), Rewarm-2 (nasopharyngeal temperature 37 $^{\circ}C$ in the both groups), CPB-off and Post-CPB (skin closure after CPB-off). Postoperaitve neuropsychologic complications were observed in all patients. All variables were compared between the two groups. Result： VMCA at Rewarm-2 was higher in the hypothermic group (153.11$\pm$8.98%) than in the normothermic group (131.18$\pm$6.94%) (p＜0.05). CAVO$_{2}$ (3.47$\pm$0.21 vs 4.28$\pm$0.29 mL/dL, p＜0.05), COE (0.30$\pm$0.02 vs 0.39$\pm$0.02, p＜0.05) and MCMRO$_{2}$ (4.71 $\pm$0.42 vs 5.36$\pm$0.45, p<0.05) at CPB-10 min were lower in the hypothermic group than in the normothermic group. The hypothermic group had higher TEO$_{2}$ than the normothermic group at CPB-10 (1,527.60$\pm$25.84 vs 1,368.74$\pm$20.03, p＜0.05), Rewarm-2 (1,757.50$\pm$32.30 vs 1,478.60$\pm$27.41, p＜0.05) and Post-CPB (1,734.37$\pm$41.45 vs 1,597.68$\pm$27.50, p＜0.05). Internal jugular bulb oxygen tension (40.96$\pm$1.16 vs 34.79$\pm$2.18 mmHg, p＜0.05), saturation (72.63$\pm$2.68 vs 64.76$\pm$2.49 %, p＜0.05) and content (8.08$\pm$0.34 vs 6.78$\pm$0.43 mL/dL, p<0.05) at CPB-10 were higher in the hypothermic group than in the normothermic group. The hypothermic group had less incidence of postoperative neurologic complication (delirium) than the normothermic group (2 vs 4 patients, p＜0.05). Lasting periods of postoperative delirium were shorter in the hypothermic group than in the normothermic group (60 vs 160 hrs, p<0.01). Conclusion: These results indicate that normothermic CPB should not be routinely applied in all cardiac surgery, especially advanced age or the clinical situations that require prolonged operative time. Moderate hypothermic CPB may have beneficial influences relatively on brain metabolism and postoperative neuropsychologic outcomes when compared with normothermic CPB.

• Korean Journal of Heritage: History & Science
• /
• v.42 no.3
• /
• pp.154-175
• /
• 2009

At the present state, studies on Gyeongbok palace are being done with history of architecture, records, and art. However, these studies have limits that they can only depend on existing buildings and record, which make it hard to research whole aspect of palaces. The foundation remains(Jeoksim) of Gyeongbok palace in the ground gives important clues that can fill the gaps of these studies. Thus I analysed jeoksim of Gyeongbok palace, assorted them by type, scale, material, and construction method. I examined jeoksim used by various types of building, and looked at changes by periods. Jeoksims are classified in 21 types. The foundation(jeoksim) varies according to types of buildings, building types and material of jeoksim also varies along the periods, and the fact proves certain peroid of time has its own jeoksim style in fashion. Jeoksims of Gyeongbok palace are divided into round-shape(I), rounded square-shape(II), rectangular-shape(III), square-shape(IV), and whole foundation of building(V) by the plane shape. They can be divided again into 21 types by construction techniques and materials used. During early Joseon(I), only three types of jeoksim; round-shape riprap jeoksim(1-1), II-1(rounded square-shape), II-2a(rounded square-shape riprap+roofingingtile brick), had been built, but as 19th century begun, all 21 types of jeoksim had built. In 19th century during Emperor Gojong, different types of jeoksim by periods were built, and especially different materials were used. During Gojong year 2(1865)~year 5(1868), in which Gyeongbok palace were rebuilt, 7 out of 10 types of jeoksim used piece of roofinging tile and brick mixture, in contrast, during Gojong year 10(1873)~13(1876), or 25(1888), 3 out of 5 types of jeoksim used sandy soil with mixture of plaster. Meanwhile palace buildings have different names by the class of owner and use such as Jeon, Dang, Hap, Gak, Jae, Heon, Nu, and Jeong, which were classified by types and buildings were built according to each level. With an analysis of jeoksim by its building types, I ascertained that jeoksim were built differently in accordance to building types(Jeon, Dang, Hap, Gak, Jae, Heon, Nu, and Jeong). By the limitation of present document, only some types of buildings such as Jeon, Dang, Gak, Bang were confirmed, as for Jeon and Gak, square-shape(IV) built with rectangular parallelepiped stone, and for Dang and Bang, rounded square-shape(IV) built with roofinginginging tile and riprap were commonly used. From the fact that other jeoksim with uncertain building names, were mostly built in early Joseon, we learn that round-shape riprap jeoksim(1-1) were commonly built. Therefore, the class of building was higher if the owner was in higher class, jeoksim is also considered to be built with the strongest and best material. And for Dang and Bang, rounded square-shape jeoksim were used, Dang has lots of II-2a (riprap + piece of roofing tile and brick rounded square-shape) type which mainly used riprap and piece of roofing tile and brick, but Bang has lots of II-2b (piece of roofing tile and brick+(riprap+piece of roofing tile and brick rounded square-shape), which paved piece of roofing tile and brick by 15~20cm above. These jeoksim by building types were confirmed to have changed its construction type by period. As for Jeon and Gak, they were built with round-shape riprap jeoksim(1-1) in early Joseon(14~15c), but in late Joseon(19c), various types of Jeoksim were built, especially square-shape(IV) were commonly built. For Dang, only changes in later Joseon were confirmed, jeoksim built in Gojong year 4(1867) mostly used mixture of riprap and piece of roofing tile and brick. In Gojong year 13(1876) or year 25(1888), unique type of plaster with sand and coal and soil layered jeoksim were built that are not found in any other building types. Through this study, I learned that various construction types of jeoksim and material were developed in later Joseon compare to early Joseon. This states that construction technique of building foundation of palace has upgraded. Above all, I learned jeoksim types are all different for various kinds of buildings. This tells us that when they constructed foundation of building, they used pre-calculated construction technique.