• Title/Summary/Keyword: 폭-두께 비

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Evaluation for Rock Cleavage Using Distributional Characteristics of Microcracks and Brazilian Tensile Strengths (미세균열과 압열인장강도의 분포 특성을 이용한 결의 평가)

  • Park, Deok-Won
    • Korean Journal of Mineralogy and Petrology
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    • v.33 no.2
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    • pp.99-114
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    • 2020
  • The characteristics of the Brazilian tensile strengths(σt) parallel to the rock cleavages in Jurassic granite from Geochang were analysed. The evaluation for the six directions of rock cleavages was performed using the parameter values on microcrack length and the above strength. The strength values of the five test specimens belonging to each direction were classified into five groups. The strength values of these five groups increase in order of group A < B < C < D < E. The close dependence between the above microcrack and strength was derived. The analysis results of this study are summarized as follows. First, the chart showing the variation and characteristics of strength among the three rock cleavages were made. In the above chart, the strength values of six directions belonging to each group were arranged in order of rift(R1 and R2), grain(G1 and G2) and hardway(H1 and H2). The strength distribution lines of the five groups concentrate in the direction of R1. And the widths among the above five lines indicating strength difference(Δσt) are the most narrowest in R1 direction. From the related chart, the variation characteristics among the two directions forming each rock cleavage were derived. G2(2)-test specimen shows higher value and lower value of the difference in strength compared to the case of G1(1)-test specimen. These kinds of phenomena are the same as the case between the test specimen H2(2) and H1(1). The strength characteristics of the above test specimens (2) suggest lower microcrack density value and higher degree of uniformity in the distribution of microcracks arrayed parallel to the loading direction compared to those of test specimens (1). The six strength values belonging to each group were arranged in increasing order in the above chart. The strength values of the test specimens belonging to both group D and E appear in order of R1 < R2 < G1 < H1 < G2 < H2. Therefore, the strength values of group D and E can be indicator values for evaluating the six directions of rock cleavages. Second, the correlation chart between slope angle(θ) and strength difference(Δσt) were made. The values of the above two parameters were obtained from the five strength distribution lines connecting between the two directions. From the chart related to rift plane(G1-H1, R'), grain plane(R1-H2, G') and hardway plane(R2-G2, H'), the slope values of linear functions increase in order of R'(0.391) < G'(0.470) < H'(0.485). Among three planes, the charts related to hardway plane show the highest distribution density among the five groups. From the related chart for rift(R1-R2, R), grain(G1-G2, G) and hardway(H1-H2, H), the slope values of linear functions increase in order of rift(0.407) < hardway(0.453) < grain(0.460). Among three rock cleavages, the charts related to rift show the highest frequency of groups belonging to the lower region. Taken together, the width of distribution of the slope angle among the three planes and three rock cleavages increase in order of H' < G < R' < R < G' < H. Third, the correlation analysis among the parameters related to microcrack length and the tensile strengths was performed. These parameters may include frequency(N), total length(Lt), mean length(Lm), median length(Lmed) and density(ρ). The correlation charts among individual parameters on the above microcrack(X) and corresponding five levels of tensile strengths for the five groups(Y) were made. From the five kinds of correlation charts, the values of correlation coefficients(R2) increase along with the five levels of strengths. The mean values of the five correlation coefficients from each chart increase in order of 0.22(N) < 0.34(Lt) < 0.38(ρ) < 0.57(Lmed) < 0.58(Lm). Fourth, the correlation chart among the corresponding maximum strength for group E(X) and the above five parameters(Y) were made. From the related chart, the values of correlation coefficient increase in order of 0.61(N) < 0.81(Lt) < 0.87(ρ) < 0.93(Lm) < 0.96(Lmed). The two parameters that have the highest correlations are median length with maximum strength. Through the above correlation analysis between microcrack and strength, the credibility for the results from this study can be enhanced.

Effects of Age of Hens, Egg Storage, and the Change of Egg Weight during Incubation on the Growth of Broiler Chicks (어미닭의 나이, 계란의 저장기간 및 부화중 난중의 변화가 육용계 병아리의 성장에 미치는 효과)

  • Suk Y. O.
    • Korean Journal of Poultry Science
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    • v.31 no.4
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    • pp.299-306
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    • 2004
  • The objective of this study was to investigate the influence of egg storage, broiler breeder age, and the change of egg weight during incubation on growth rate of chicks and 43-day-old dressing percentage. The trials involved hatching eggs obtained from 27-wk-old hens and stored for 6 d for the Young-EXP group, from 28-wk-old hens and stored for 0 d for the Young-CON group, from 51-wk-old hens and stored for 6 d for the Old-EXP group, and from 52-wk-old hens and stored for 0 d for the Old-CON group, The hens were two commercial broiler breeder flocks of the same strain (Cobb) but of different egg producing stages(early and middle stages of egg production). The chicks were grown on floor pens for 6 wks, The differences of setting egg weights between Old-CON and Old-EXP groups were 1 g, but those between Young-CON and Young-EXP groups were 2.9 g(P<0,05). The loss of egg weight during 18 d incubation did not greatly differ among four groups, but the loss of egg weight during 21 d incubation was significantly (P<0.05) more in the middle stage of egg production groups than in the early stage of egg production groups. The mean birth weights of the middle stage of egg production groups were significantly(P<0,05) heavier by 8,7 g than those of the early stage of egg production groups; however, the differences of 6-wk-old body weight were not significant between egg producing stages. The differences of body weights in both egg producing stages were not significantly influenced by egg storage period in overall wks of ages. Egg storage and hen age did not greatly influence to the 43 d dressing percentages, either, The correlations of the setting egg weight with 18 d egg weight during incubation, growth rate of chicks, or 43 d dressing percentage were not significant.

The Influence of Feeding Dietary Differences on Growth Performance and Carcass Quality in Finishing Pigs (사료조성 차이가 돼지 생산 및 도체형질에 미치는 영향)

  • 진상근;김일석;송영민;하경희;이성대;김회윤;주선태;박구부
    • Food Science of Animal Resources
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    • v.23 no.1
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    • pp.9-15
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    • 2003
  • All diets were based on feeds of fattening period pigs(LY x D, ca. 90 kg) with six treatments, which were the control, containing 5% beef tallow(C), 3% beef tallows and 2% perilla seeds oil(T1), 250 ppm vit. E(${\alpha}$-tocopheryl acetate) in T1(T2), 3% beef tallow and 2% squid viscera oil(T3), 250 ppm vit. E in T3(T4), and 3% beef tallow and 2% CLA(T5), respectively. Produced porks and their carcass characteristics were as follows. The daily gain of pigs was higher in T2 and 73 than any other treatments(p<0.05). Its T2 and T3 was 3.71 and 3.80 respectively, however, there was no significance in feed intake. The highest back fat thickness was shown in control group on market weight, while there was no significant difference on their initial weight. Loin-eye muscle area did not show any significant difference on initial weight and on market weight, however, its T5 was about twice as large as T2's. Content of triglyceride in blood was high in control group as compared to others; especially, the values for T3, T4 and T5 were significantly low(p <0.05). There was no significant difference in total cholesterol contents, and the ratio of HDL cholesterol/total cholesterol was higher in vit. E treated samples than untreated sample. Atherogenic index was high in sample with T3 and low in sample with T2. The perilla seed oil, squid fish oil, and vit. E decreased atherogenic index. Dressing percentage, back fat thickness, and grade did not show any significant difference(p >0.05); however, T2, C and T3, T1 and T5 showed 4.67, 4.29, 4.00 respectively, in grades.

Effects of Increasing Market Weight of Finishing Pigs on Backfat Thickness, Incidence of the 'Caky-fatty' Belly, Carcass Grade, and Carcass Quality Traits (비육돈의 출하체중 증가가 등지방두께, '떡지방' 삼겹살 발생률, 도체등급 및 도체의 품질 특성에 미치는 영향)

  • Park, Man Jong;Park, Byung Chul;Ha, Duck-Min;Kim, Jin-Bo;Jang, Kyoung-Soon;Lee, Do-Hyun;Kim, Gwan-Tae;Jin, Sang-Keun;Lee, C. Young
    • Journal of Animal Science and Technology
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    • v.55 no.3
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    • pp.195-202
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    • 2013
  • The present study was undertaken to investigate the effects of increasing pig market weight on the incidence of the 'caky-fatty' belly, carcass grade and carcass quality traits. To this end, 500 (Yorkshire ${\times}$ Landrace) ${\times}$ Duroc market pigs consisting of equal numbers of barrows and gilts were slaughtered at body weights ranging from 85 to 150 kg and their carcasses were analyzed. Backfat thickness (BFT; mm) of the barrows and gilts regressed on live weight (kg) linearly as follows: BFT (y) = 0.1827x + 3.4825 ($r^2$ = 0.4671) and y = 0.2015x-0.6972 ($r^2$ = 0.4736), respectively. The caky-fatty belly, which, by definition of the present study, had = 55% fat by weight in the dorsal-side half of a 5 cm-wide belly strip between the $11^{th}$ and $12^{th}$ ribs, was found in 10 carcasses from barrows. However, no belly was condemned as 'caky-fatty' by the retailers. Total number of carcasses which were down-graded on account of overweight was as many as 101 (20.2%). The $1^+A$-grade carcasses exhibited a superior intramuscular fat score to all other grades, but except for this and the defective quality traits, no visible differences were found in carcass quality among different carcass grades. In conclusion, the current carcass grading system, which is sparingly reflective of the carcass quality and also under-evaluates the larger but otherwise normal carcasses, may as well be revised. Moreover, the incidence of the caky-fatty belly appears not to be a critical factor to be considered when increasing the pig market weight.

The fracture resistance of heat pressed ceramics with wire reinforcement (금속선 강화에 따른 열 가압 도재의 파절저항)

  • Jo, Deuk-Won;Dong, Jin-Keun;Oh, Sang-Chun;Kim, Yu-Lee
    • The Journal of Korean Academy of Prosthodontics
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    • v.47 no.2
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    • pp.191-198
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    • 2009
  • Statement of problem: Ceramics have been important materials for the restoration of teeth. The demands of patients for tooth-colored restorations and the availability of various dental ceramics has driven the increased use of new types of dental ceramic materials. Improved physical properties of theses materials have expanded its use even in posterior crowns and fixed partial dentures. However, ceramic still has limitation such as low loading capability. This is critical for long-span bridge, because bridge is more subject to tensile force. Purpose: The wire reinforced ceramic was designed to increase the fracture resistance of ceramic restoration. The purpose of this study was to evaluate the fracture resistance of wire reinforced ceramic. Material and methods: Heat pressed ceramic(ingot No.200 : IPS Empress 2, Ivoclar Vivadent, Liechtenstein) and Ni-Cr wire(Alfa Aesar, Johnson Matthey Company, USA) of 0.41 mm diameter were used in this study. Five groups of twelve uniform sized ceramic specimens(width 4 mm, thickness 2 mm, length 15 mm) were fabricated. Each group had different wire arrangement. Wireless ceramic was used as control group. The experimental groups were divided according to wire number and position. One, two and three strands of wires were positioned on the longitudinal axis of specimen. In another experimental group, three strands of wires positioned on the longitudinal axis and five strands of wires positioned on the transverse axis. Three-point bending test was done with universal testing machine(Z020, Zwick, Germany) to compare the flexural modulus, flexural strength, strain at fracture and fracture toughness of each group. Fractured ceramic specimens were cross-sectioned with caborundum disc and grinded with sandpaper to observe interface between ceramic and Ni-Cr wire. The interface between ceramic and Ni-Cr wire was analyzed with scanning electron microscope(JSM-6360, JEOL, Japan) under platinum coating. Results: The results obtained were as follows: 1. The average and standard deviation in flexural modulus, flexural strength and fracture toughness showed no statistical differences between control and experimental groups. However, strain was significantly increased in wire inserted ceramics(P<.001). 2. Control group showed wedge fracture aspects across specimen, while experimental groups showed cracks across specimen. 3. Scanning electron microscopic image of cross-sectioned and longitudinally-sectioned specimens showed no gap at the interface between ceramic and Ni-Cr wire. Conclusion: The results of this study showed that wire inserted ceramics have a high strain characteristic. However, wire inserted ceramics was not enough to use at posterior area of mouth in relation to flexural modulus and flexural strength. Therefore, we need further studies.

Artificial Multiplication of the Black Soldier Fly(BSF), Hermetia illucens(Diptera: Stratmyidae) Using the Livestock Feces (가축분뇨를 이용한 동애등에 증식기술 개발)

  • Choi, Young-Cheol;Lee, Sang-Beom;Park, Kwan-Ho;Nam, Sung-Hee;Kim, Jong-Gill;Kim, Won-Tae;Choi, Ji-Young
    • Journal of Sericultural and Entomological Science
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    • v.50 no.2
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    • pp.63-70
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    • 2012
  • This study was conducted to investigated the distribution, ecological character and life cycle of Black Soldier Fly(BSF), Hermetia illucens, to determine effects of BSF on composing ability to the livestock feces. The distribution of BSF was defined in all parts of the country in Korea. Its main habitat was found to be areas near cattle sheds, feces sheds, living waste dump grounds, and food waste dump grounds. Excellent species of the bio-conversion using the livestock feces were selected out of two kinds of solider flies(Hermetia illucens and Ptecticus tenebrifer). And effects of BSF on composing ability to the livestock feces were pig feces 0.5 g, cattle feces 0.43 g and chicken feces 0.3 g per a larvae of BSF. In the examination of the ability of BSF to decompose food waste, volume of the livestock feces decreased by weight pig feces 77, cattle feces 83.62 and chicken feces 80%. Observed characteristics of BSF larvae and pupae stage were by developmental stage may be summarized as follows: size and length of larvae and pupae of BSF were higher than in pig feces and mixed sawdust treatments. In order to develop artificial indoor rearing techniques, The pupation and emergence rate were not visible the difference but important factor of the mating and egg-laying was a sun light. And it was visible the difference in mating ratio. Mating rate of H. illucens by seasonal change was the highest from May to July. Mating mostly occurred between 10 : 00 and 12 : 00 during which light intensity is high. As the egg-laying medium for artificial egg collection, calf feed and food waste were most effective. The ratio of egg-laying medium is waste food : sawdust(1 : 1) in volume. For egg-laying materials, flower foam and wood with holes were used; holes sized 3 ~ 5 mm in diameter, 7 ~ 10 mm in depth were most preferred for egg-laying.

Comparison of Gap Pressure in Opening Wedge High Tibial Osteotomy versus Compressive Strength of Allogenous Wedge Bone Blocks (경골 근위부 개방 절골술 시 개방부 압력과 동종 쐐기 골편의 최대압축하중 비교)

  • Yoon, Kyoung Ho;Kim, Jung Suk;Kwon, Yoo Beom;Kim, Eung Ju;Lee, Myeong-Kyu;Kim, Sang-Gyun
    • Journal of the Korean Orthopaedic Association
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    • v.55 no.2
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    • pp.127-134
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    • 2020
  • Purpose: The aims of this study were (1) to investigate the relationship between the characteristics of allogenic bone block and the compressive strength of an allogenic bone block measured by biomechanical experiments, and (2) to compare the maximum pressure load of allogenic bone block with the gap pressure measured at the high tibial opening osteotomy. Materials and Methods: Ten patients who provided informed consent for gap pressure measurements during opening wedge high tibial osteotomy (OWHTO) were included. The gap pressures were measured at 1 mm intervals while opening the osteotomy site from 8 mm to 14 mm. Seventeen U-shaped allogenous wedge bone blocks were made from the femur, tibia, and humerus. The height, width, cross-sectional area, and cortex thickness of the bone blocks were measured, along with the maximum compressive load just before breakage. The relationship between these characteristics and the maximum pressure load of the bone blocks was evaluated. The gap pressures measured in OWHTO were compared with the maximum pressure loads of the allogenous wedge bone blocks to evaluate the possibility of inserting allogenous wedge bone blocks into the osteotomy site without a distractor in OWHTO. Results: The OWHTO gap pressure increased with increasing osteotomy site opening. The mean gap pressure, which occurred at a 14-mm opening, was 282±93 N; the maximum pressure was 427 N. The maximum pressure load of the allografts was 13,379±6,469 N (minimum, 5,868; maximum, 29,130 N) and was correlated significantly with the cortical bone thickness (correlation coefficient=0.693, p=0.002) and cross-sectional area (correlation coefficient=0.826, p<0.001). Depending on the sterilization method, the maximum pressure loads for the bone blocks were 13,406±5,928 N for freeze-dried and 13,348±7,449 N for fresh frozen. The maximum compressive load of the allogenous wedge bone blocks was 13.7-times greater than that in OWHTO opened to 14 mm (5,868 N vs. 427 N). Conclusion: The compressive strength of allogenous wedge bone blocks was sufficiently greater than the gap pressure in OWHTO. Therefore, allogenous wedge bone blocks can be inserted safely into the osteotomy site without a distractor.

Evaluation of Spectral Band Adjustment Factor Applicability for Near Infrared Channel of Sentinel-2A Using Landsat-8 (Landsat-8을 활용한 Sentinel-2A Near Infrared 채널의 Spectral Band Adjustment Factor 적용성 평가)

  • Nayeon Kim;Noh-hun Seong;Daeseong Jung;Suyoung Sim;Jongho Woo;Sungwon Choi;Sungwoo Park;Kyung-Soo Han
    • Korean Journal of Remote Sensing
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    • v.39 no.3
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    • pp.363-370
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    • 2023
  • Various earth observation satellites need to provide accurate and high-quality data after launch. To maintain and enhance the quality of satellite data, it is crucial to employ a cross-calibration process that accounts for differences in sensor characteristics, such as the spectral band adjustment factor (SBAF). In this study, we utilized Landsat-8 and Sentinel-2A satellite imagery collected from desert sites in Libya4, Algeria3, and Mauritania2 among pseudo-invariant calibration sites to calculate and apply SBAF, thereby compensating the uncertainties arising from variations in bandwidths. We quantitatively compared the reflectance differences based on the similarity of bandwidths, including Blue, Green, Red, and both the near-infrared (NIR) narrow, and NIR bands of Sentinel-2A. Following the application of SBAF, significant results with reflectance differences of approximately 1% or less were observed for all bands except NIR. In the case of the Sentinel-2A NIR band, it exhibited a significantly larger bandwidth difference compared to the NIR narrow band. However, after applying SBAF, the reflectance difference fell within the acceptable error range (5%) of 1-2%. It indicates that SBAF can be applied even when there is a substantial difference in the bandwidths of the two sensors, particularly in situations where satellite utilization is limited. Therefore, it was determined that SBAF could be applied even when the bandwidth difference between the two sensors is large in a situation where satellite utilization is limited. It is expected to be helpful in research utilizing the quality and continuity of satellite data.

Broadening the Understanding of Sixteenth-century Real Scenery Landscape Painting: Gyeongpodae Pavilion and Chongseokjeong Pavilion (16세기(十六世紀) 실경산수화(實景山水畫) 이해의 확장 : <경포대도(鏡浦臺圖)>, <총석정도(叢石亭圖)>를 중심으로)

  • Lee, Soomi
    • MISULJARYO - National Museum of Korea Art Journal
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    • v.96
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    • pp.18-53
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    • 2019
  • The paintings Gyeongpodae Pavilion and Chongseokjeong Pavilion were recently donated to the National Museum of Korea and unveiled to the public for the first time at the 2019 special exhibition "Through the Eyes of Joseon Painters: Real Scenery Landscapes of Korea." These two paintings carry significant implications for understanding Joseon art history. Because the fact that they were components of a folding screen produced after a sightseeing tour of the Gwandong regions in 1557 has led to a broadening of our understanding of sixteenth-century landscape painting. This paper explores the art historical meanings of Gyeongpodae Pavilion and Chongseokjeong Pavilion by examining the contents in the two paintings, dating them, analyzing their stylistic characteristics, and comparing them with other works. The production background of Gyeongpodae Pavilion and Chongseokjeong Pavilion can be found in the colophon of Chongseokjeong Pavilion. According to this writing, Sangsanilro, who is presumed to be Park Chung-gan (?-1601) in this paper, and Hong Yeon(?~?) went sightseeing around Geumgangsan Mountain (or Pungaksan Mountain) and the Gwandong region in the spring of 1557, wrote a travelogue, and after some time produced a folding screen depicting several famous scenic spots that they visited. Hong Yeon, whose courtesy name was Deokwon, passed the special civil examination in 1551 and has a record of being active until 1584. Park Chung-gan, whose pen name was Namae, reported the treason of Jeong Yeo-rip in 1589. In recognition of this meritorious deed, he was promoted to the position of Deputy Minister of the Ministry of Punishments, rewarded with the title of first-grade pyeongnan gongsin(meritorious subject who resolved difficulties), and raised to Lord of Sangsan. Based on the colophon to Chongseokjeong Pavilion, I suggest that the two paintings Gyeongpodae Pavilion and Chongseokjeong Pavilion were painted in the late sixteenth century, more specifically after 1557 when Park Chung-gan and Hong Yeon went on their sightseeing trip and after 1571 when Park, who wrote the colophon, was in his 50s or over. The painting style used in depicting the landscapes corresponds to that of the late sixteenth century. The colophon further states that Gyeongpodae Pavilion and Chongseokjeong Pavilion were two paintings of a folding screen. Chongseokjeong Pavilion with its colophon is thought to have been the final panel of this screen. The composition of Gyeongpodae Pavilion recalls the onesided three-layered composition often used in early Joseon landscape paintings in the style of An Gyeon. However, unlike such landscape paintings in the An Gyeon style, Gyeongpodae Pavilion positions and depicts the scenery in a realistic manner. Moreover, diverse perspectives, including a diagonal bird's-eye perspective and frontal perspective, are employed in Gyeongpodae Pavilion to effectively depict the relations among several natural features and the characteristics of the real scenery around Gyeongpodae Pavilion. The shapes of the mountains and the use of moss dots can be also found in Welcoming an Imperial Edict from China and Chinese Envoys at Uisungwan Lodge painted in 1557 and currently housed in the Kyujanggak Institute for Korean Studies at Seoul National University. Furthermore, the application of "cloud-head" texture strokes as well as the texture strokes with short lines and dots used in paintings in the An Gyeon style are transformed into a sense of realism. Compared to the composition of Gyeongpodae Pavilion, which recalls that of traditional Joseon early landscape painting, the composition of Chongseokjeong Pavilion is remarkably unconventional. Stone pillars lined up in layers with the tallest in the center form a triangle. A sense of space is created by dividing the painting into three planes(foreground, middle-ground, and background) and placing the stone pillars in the foreground, Saseonbong Peaks in the middle-ground, and Saseonjeong Pavilion on the cliff in the background. The Saseonbong Peaks in the center occupy an overwhelming proportion of the picture plane. However, the vertical stone pillars fail to form an organic relation and are segmented and flat. The painter of Chongseokjeong Pavilion had not yet developed a three-dimensional or natural spatial perception. The white lower and dark upper portions of the stone pillars emphasize their loftiness. The textures and cracks of the dense stone pillars were rendered by first applying light ink to the surfaces and then adding fine lines in dark ink. Here, the tip of the brush is pressed at an oblique angle and pulled down vertically, which shows an early stage of the development of axe-cut texture strokes. The contrast of black and white and use of vertical texture strokes signal the forthcoming trend toward the Zhe School painting style. Each and every contour and crack on the stone pillars is unique, which indicates an effort to accentuate their actual characteristics. The birds sitting above the stone pillars, waves, and the foam of breaking waves are all vividly described, not simply in repeated brushstrokes. The configuration of natural features shown in the above-mentioned Gyeongpodae Pavilion and Chongseokjeong Pavilion changes in other later paintings of the two scenic spots. In the Gyeongpodae Pavilion, Jukdo Island is depicted in the foreground, Gyeongpoho Lake in the middle-ground, and Gyeongpodae Pavilion and Odaesan Mountain in the background. This composition differs from the typical configuration of other Gyeongpodae Pavilion paintings from the eighteenth century that place Gyeongpodae Pavilion in the foreground and the sea in the upper section. In Chongseokjeong Pavilion, stone pillars are illustrated using a perspective viewing them from the sea, while other paintings depict them while facing upward toward the sea. These changes resulted from the established patterns of compositions used in Jeong Seon(1676~1759) and Kim Hong-do(1745~ after 1806)'s paintings of Gwandong regions. However, the configuration of the sixteenth-century Gyeongpodae Pavilion, which seemed to have no longer been used, was employed again in late Joseon folk paintings such as Gyeongpodae Pavilion in Gangneung. Famous scenic spots in the Gwandong region were painted from early on. According to historical records, they were created by several painters, including Kim Saeng(711~?) from the Goryeo Dynasty and An Gyeon(act. 15th C.) from the early Joseon period, either on a single scroll or over several panels of a folding screen or several leaves of an album. Although many records mention the production of paintings depicting sites around the Gwandong region, there are no other extant examples from this era beyond the paintings of Gyeongpodae Pavilion and Chongseokjeong Pavilion discussed in this paper. These two paintings are thought to be the earliest works depicting the Gwandong regions thus far. Moreover, they hold art historical significance in that they present information on the tradition of producing folding screens on the Gwandong region. In particular, based on the contents of the colophon written for Chongseokjeong Pavilion, the original folding screen is presumed to have consisted of eight panels. This proves that the convention of painting eight views of Gwangdong had been established by the late sixteenth century. All of the existing works mentioned as examples of sixteenth-century real scenery landscape painting show only partial elements of real scenery landscape painting since they were created as depictions of notable social gatherings or as a documentary painting for practical and/or official purposes. However, a primary objective of the paintings of Gyeongpodae Pavilion and Chongseokjeong Pavilion was to portray the ever-changing and striking nature of this real scenery. Moreover, Park Chung-gan wrote a colophon and added a poem on his admiration of the scenery he witnessed during his trip and ruminated over the true character of nature. Thus, unlike other previously known real-scenery landscape paintings, these two are of great significance as examples of real-scenery landscape paintings produced for the simple appreciation of nature. Gyeongpodae Pavilion and Chongseokjeong Pavilion are noteworthy in that they are the earliest remaining examples of the historical tradition of reflecting a sightseeing trip in painting accompanied by poetry. Furthermore, and most importantly, they broaden the understanding of Korean real-scenery landscape painting by presenting varied forms, compositions, and perspectives from sixteenth-century real-scenery landscape paintings that had formerly been unfound.

The Changes in the Electrical Properties of $\textrm{BaTiO}_3$-based PTCR Materials due to the addition of (Ca, Sr)$\textrm{TiO}_3$ ($\textrm{TiO}_3$첨가에 의한 $\textrm{BaTiO}_3$계 PTCR 물질의 전기적 특성변화에 대한 연구)

  • Joo, Ji-Won;Kim, Jong-Hwan;Kim, Hwan;Park, Soon-Ja
    • Korean Journal of Materials Research
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    • v.7 no.4
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    • pp.347-353
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    • 1997
  • BaTiO$_{3}$물질은 뛰어난 유전체로 널리 알려져 왔으며 특히 Heywang등이 제안한 PTCR특성은 이 물질의 응용범위를 세라믹 필터, 회로보호소자, 온도감지소자 및 저항가열장치 등으로 확대시켰다. 이러한 특성의 발현기구는 아직까지 밝혀지지 않은 상태이지만 제 특성을 향상시키기 위한 노력은 계속되어왔다. 특히 개발목적에 맞게 온도에 따른 정저항 특성(PTCR; Positive temperature constnat of resistivity phenomena)을 설계하려는 시도가 계속되어 왔으며 그 중에서도 페로브스카아트계의 2가와 4가의 양이온 자리를 등가나 원자가가 다른 양이온으로 치환하여 특성을 개선하려는 시도가 계속되어 왔다. 특히 $Ca^{2+}$나 Sr$^{2+}$$Ba^{2+}$자리를 치환할 수 있는 물질로 개별적인 첨가에 대한 연구는 많은 연구자들에 의해 진행된 상태이지만 최종적인 영향이나 해석에 대해서는 연구자들간에 이견이 많은 상태이다. 이번 실험에서는 BaTiO$_{3}$계에 합성한 (Ca, Sr)TiO$_{3}$를 Ca와 Sr의 상대적인 비를 변화시키면서 전체적인 첨가량을 변화시켜 그에 따른 전기적 특성 및 미세구조를 살펴보았다. (Ca, Sr)TiO$_{3}$의 첨가로 상온저항 및 PTCR특성을 변화시킬 수 있었으며 이를 통해 PTCR물질의 활용범위를 넓힐 수 있는 발판을 마련할 계기가 되었다. 특히 기존의 연구가 주로 개별적인 Ca나 Sr의 첨가에 의한 미세구조와 전기적 특성변화의 연구에 치중해 있었던 것과는 달리 Sr과 Ca을 함께 치환하여 상대적인 비가 특성에 더 중요한 영향을 끼치는 것을 확인하였으며 적절한 합성비를 선택하면 퀴리온도에서의 저항변화폭을 유지하면서 상온저항을 낮출 수 있음을 확인하였다.문했던 연구소인 Shanghai Research Center of Biotechnology, Shanghai Institute of Industrial Microbiology 및 Scientific Research Institute of Food and Fermentation Industry을 소개하고저 한다. 짧은 기간의 방문이라 주로 해당연구소의 자체소개 자료를 중심으로 방문하면서 느낀점을 기술하고저 한다.초염기성암 기원의 사문암이 열수변질작용을 받아 생성되었음을 명확하게 지시하며, 따라서 활석 광석내에 존재하는 녹니석은 활석의 근원 광물로서 녹니석편암 및 녹니석 편마암 매의 녹니석이 활석화되고 남은 잔존광물이 아니라, 주변암에 의해 성분상의 영향을 받은 열수와 사문암과의 변질교대작용에 의한 활석화과정 중에 주로 생성된 것으로 추정된다. 이러한 결과는 연구지역의 활석광상이 초염기성암의 사문암화 작용과 활석화 작용의 두 가지 변질작용에 의해 형성되어졌음을 알려준다.농도 증가 없이 폐 조직에 약 50배 정도의 고농도 cisplatin을 투여할 수 있었으며, 또한 분리 폐 관류 시 cisplatin에 의한 직접적 폐 독성은 발견되지 않았다이 낮았으나 통계학적 의의는 없었다[10.0%(4/40) : 8.2%(20/244), p>0.05]. 결론: 비디오흉강경술에서 재발을 낮추기 위해 수술시 폐야 전체를 관찰하여 존재하는 폐기포를 놓치지 않는 것이 중요하며, 폐기포를 확인하지 못한 경우와 이차성 자연기흉에 대해서는 흉막유착술에 더 세심한 주의가 필요하다는 것을 확인하였다. 비디오흉강경수술은 통증이 적고, 입원기간이 짧고, 사회로의 복귀가 빠르며, 고위험군에 적용할 수 있고, 무엇보다도 미용상의 이점이 크다는 면에서 자연기흉에 대해 유용한 치료방법임에는 틀림이 없으나 개흉술에 비해 재발율이 높고 비용이 비싸다는 문제가 제기되고 있는 만큼 더 세심한 주의와 장기 추적관찰이 필요하리라 사료된다.

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