• Structural Engineering and Mechanics
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• 제51권5호
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• pp.793-808
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• 2014

The goal of this study is to evaluate and design steel plates with optimal material distributions achieved through a specific material topology optimization by using a CCARAT (Computer Aided Research Analysis Tool) as an optimizer, topologically optimally updating node densities as design variables. In typical material topology optimization, optimal topology and layouts are described by distributing element densities (from almost 0 to 1), which are arithmetic means of node densities. The average element densities are employed as material properties of each element in finite element analysis. CCARAT may deal with material topology optimization to address the mean compliance problem of structural mechanical problems. This consists of three computational steps: finite element analysis, sensitivity analysis, and optimality criteria optimizer updating node densities. The present node density based design via CCARAT using node densities as design variables removes jagged optimal layouts and checkerboard patterns, which are disadvantages of classical material topology optimization using element densities as design variables. Numerical applications that topologically optimize reinforcement material distribution of steel plates of a cantilever type are studied to verify the numerical superiority of the present node density based design via CCARAT.

• Applied Microscopy
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• 제22권1호
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• pp.42-54
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• 1992

To understand the structural changes of the myocardial myocytes and endothelial cells in ischemic and reperfused heart, and to elucidate their roles in those conditions, the authors observed cat and rat myocardium ultrastructurally and evaluated them with morphometric techniques. In cat, mild ischemia and moderate degree reperfusion injury was induced by ligation of the anterior interventricular branch of left coronary artery and reperfusion. In rat, severe ischemia and irreversible reperfusion iniury was made using in vitro Langendorff techniques. In normal cat myocytes, the volume densities of cytoplasm, myofibrils, mitochondria, sarcoplasmic reticulum and T tubules were $0.11{\pm}0.013,\;0.51{\pm}0.096,\;0.25{\pm}0.082,\;0.09{\pm}0.008,\;0.02{\pm}0.010$ (Mean${\pm}$S.D.) respectively, and the myofibril/mitochondria ratio was $2.33{\pm}1.379$. The numerical density and average volume of mitochondria were $0.76{\pm}0.210/{\mu}m^3$ and $0.33{\pm}0.057{\mu}m^3$ respectively. In normal cat endothelial cells, the volume densities of cytoplasm, cytoplasmic vesicles, tubular systems (including endoplasmic reticulum and Golgi apparatus) and mitochondria were $0.43{\pm}0.023,\;0.28{\pm}0.007,\;0.22{\pm}0.021,\;0.03{\pm}0.014$ respectively. The mean thickness of endothelial cells was $230{\pm}45.2{\mu}m$. The numerical density and average volume of cytoplasmic vesicles were $508{\pm}55.0/{\mu}m^3,\;578{\pm}104.8nm^3$ respectively. In cat myocytes which received mild ischemic injury, the volume densities of organelles were not changed significantly in ischemic and reperfusion states. In reperfusion group myocytes, the numerical density of mitochondria was decreased significantly and the average volume was increased significantly. In endothelial cells, the volume density of tubular system in ischemic group and the average volume of cytoplasmic vesicles in reperfusion group were increased significantly. In rat myocytes which received severe ischemic injury, the volume density and average volume of mitochondria were increased significantly, and the volume density of sarcoplasmic reticulum and numerical density of mitochondria were decreased significantly in both ischemic and reperfusion groups. In ischemic and reperfused endothelial cells, the volume density and numerical density of cytoplasmic vesicles, the volume density of cytoplasm were decreased significantly. The volume densities of tubular system were increased significantly in both ischemic and reperfused groups. The volume density of mitochondria in ischemic group and the average volume of cytoplasmic vesicles in reperfusion group showed significant increase. The authors, based on the above observations, conclude that the mitochondria of myocytes and the cytoplasmic vesicles of endothelia are the first group of targets in ischemic and reperfusion injury and in this respect, the degree of ischemic insult is not significant. The role of myocyte mitochondria in reperfusion injury may be insignificant, but endothelial cells may contribute actively to reperfusion injury.

• 한국지반공학회논문집
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• 제33권1호
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• pp.79-91
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• 2017

반복단순전단시험기를 이용하여 해양실트질 모래의 상대밀도 변화에 따른 비배수전단파괴 거동에 대해 평균전단응력과 반복전단응력이 미치는 영향을 평가하였다. 시험결과 반복전단 변형모드는 상대밀도가 달라지더라도 유사한 양상을 보였으며, 평균전단응력과 반복전단응력으로부터 큰 영향을 받았다. 파괴에 필요한 반복하중 횟수는 반복전단응력비, 상대밀도, 그리고 평균전단응력비의 순서로 좌우되는 것으로 나타났다. 본 논문에서는 조밀한 지반과 느슨한 지반에서 상대밀도 변화에 따른 응력기반 파괴경로의 변화를 2차원과 3차원으로 제시하였으며, 3차원 파괴선도는 조밀한 지반 조건에 대해서만 한정된 한계점을 보완하여 지반의 상대밀도에 따라 반복전단응력비, 평균전단응력비, 반복하중 횟수 등의 설계 조건을 결정 할 수 있는 아주 유용한 설계도구로 활용 가능하다.

• Parasites, Hosts and Diseases
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• 제53권3호
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• pp.289-298
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• 2015

The infection status of freshwater fish with digenetic trematode metacercariae was examined in water systems of Hantangang and Imjingang (River), the Republic of Korea. A total of 877 (594 from Hantangang and 283 from Imjingang) fishes were examined by the artificial digestion methods. Clonorchis sinensis metacercariae were detected in 7 (1.2%) fishes (in 3 spp.) from Hantangang in Cheorwon-gun, Gangwon-do, and 40 (14.1%) fishes (in 7 spp.) from Munsancheon in Paju-si, Gyeonggi-do. The average densities were 1.9 and 35.6 per fish infected, respectively. Metagonimus spp. metacercariae were detected in 312 (52.5%) and 113 (39.9%) fishes from Hantangang and Imjingang, and their average densities were 47.5 and 9.6 per fish infected, respectively. Centrocestus armatus metacercariae were found in 161 (27.1%) and 70 (24.7%) fishes from Hantangang and Imjingang, and their average number per fish infected was 694 and 82, respectively. Echinostoma spp. metacercariae were detected in 50 (8.4%) and 94 (33.2%) fishes from Hantangang and Imjingang, and their average densities were 9.6 and 23.1 per fish infected, respectively. The infection status of fishes with metacercariae of Stephanoprora spp., Diplostomum spp., Clinostomum complanatum, Metorchis orientalis, and Metorchis taiwanensis were analyzed by surveyed regions. Conclusively, it was confirmed that C. sinensis metacercariae were quite commonly detected in fishes from Munsancheon but rarely from other localities, whereas the metacercariae of other digenetic trematodes were relatively prevalent in fishes from water systems of Hantangang and Imjingang in Korea.

• 복식
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• 제57권1호
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• pp.163-175
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• 2007

This study examines 74 pieces of textiles of Daegaya found in the Jeesan-dong Tomb and Saeng-cho Tomb, and analyzes their characteristics and weaving techniques. Dagaya is known to have produced ramie and hemp from bast fibers. The hemp textiles were all woven in plain weave, and the ramie textiles were woven either in plain weave or plain braid. The ramie textiles were slightly more dense compared to the hemp textiles, however, both had average densities between 0.92 to 0.93, showing that they are balanced plain weave textiles. It was also found that S twist threads were used in the production of the hemp and ramie textiles. The dyed textiles on iron remains were found to be the oldest textiles to use dying techniques for patterns. Silk textiles were woven in plain weave, twill weave, and leno weave. All of the silk were made with non-twisted thread. The densities were between 30 to 58.3 and the the density rates were 1.0 to 2.5 for plain weave silk, this showed that varieties of plain weaver created by different densities of warp and well. The average density of cho was $53.4{\times}22.5/cm^2$ the density rate was about 2.40, therefore warp was woven more dense compared to the weft. There were degummed and raw silk used in silk textiles, but most of them were found to be degummed thread.

• 수산해양교육연구
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• 제25권1호
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• pp.78-86
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• 2013

In order to analyze the pollution extent of small plastic debris(SPD) ashore on the shoreline of coastal flow, 12 of survey was conducted at Song-Jung beach of Busan for several years. The sampled beach was divided into 9 sites with unit area($m^2$). Many of SPD were detected in the southern part of the beach and classified into 11 items as P1 to P11 according to the contents. Average densities of total items' weight were $2.955g/m^2$ and weights of P2, P3 item were composed of about 64% among them. And average densities of total items' quantity were $56.259ea/m^2$ and quantities of P6 only were composed of about 63%. Seeing the seasonal variation, fall season was abundant extremely whereas nearly nothing in spring. The correlation of weights and quantities have reliable coefficients to some extent on sites and season but nearly don't have reliances on item, tide, wind and precipitation. Many researching data were required if possible in order to discussing about the correlation.

• 한국세라믹학회지
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• 제33권10호
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• pp.1177-1185
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• 1996

Y-TZP/Ce-TZP ceramics having relative sintered densities of>95% average grain sizes of 0.36$\mu\textrm{m}$ microhar-dness of 1150 kg/mm2 fracture strength of 390-830 MPa and toughness of 6.4-10.2 MPa$.$mm1/2 were prepared by conventional sintering of 3 mol% Y2O3-ZrO2 and 12 mol% CeO2-ZrO2 powders at 1400 and 1500$^{\circ}C$ The average grain sizes of Y-TZP/Ce-TZP ceramics were mainly governed by those of Ce-TZP. White increasing Ce-TZP content toughness increased while microhardness and fracture strength decreased. With comparing microhardness and toughness fracture strength was more sensitive on not only grain size but also other factors such as microstructural and compositional variations. The densification of Y-TZP/Ce-TZP cermaics was not greatly affected by composition and soaking time at temperature over 1400$^{\circ}C$ With increasing CE-TZP content the stability of t-ZrO2 decreased under thermal aging in air whereas increased in hydrothermal atmosphere and aqueous solution.

• 한국수산과학회지
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• 제36권2호
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• pp.163-169
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• 2003

The floating bead filter was tested for treatment of aquacultural water in a pilot-scale recirculating aquaculture system. Performance of floating bead filter on the removal of total suspended solids (TSS) and the treatment of nitrogen sourer such as total ammonia nitrogen (TAN), nitrite nitrogen and nitrate nitrogen were evaluated. The system was stocked with Nile tilapia at an initial rearing densities of $5\%\;and\;7\%$ over 30 days. The average TSS removal rates were $43.0\;g/m^2{\cdot}day\;and\;39.5\;g/m^2{\cdot}day$ for rearing density of $5\%\;and\;7\%$, respectively. As rearing density increased from $5\%\;to\;7\%$. the TAN removal efficiency decreased from $22.0\%\;to\;17.7\%$. At the rearing densities of $5\%\;and\;7\%$, the average TAN removal rates and removal efficiencies were $38.8\;g/m^2{\cdot}day,\;15.6\%\;and\;37.8\;g/m^2{\cdot}day.\;17.7\%,$ respectively. The average TAN removal rate was $37.8-38.8\;g/m^3{\cdot}day.$ The oxygen consumption by floating bead filter was higher than theoretical oxygen consumption rate by nitrification.

• 농업과학연구
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• 제49권4호
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• pp.927-936
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• 2022

The effects of seasonal differences and crating densities on the preslaughter losses, breast meat quality, and physiological indices of broilers were determined. A total of 600 broilers aged 35 days were divided into 10 treatment groups based on five crating densities (10.3, 11.5, 12.8, 14.1, 15.4 birds·m^-2) with two seasons (i.e., summer and winter) to give six replicates and were placed at various locations in the truck. The birds were transported in crates having dimensions of 1.0 m × 0.78 m × 0.26 m. The transportation distance was 20 km for 40 minutes (average 30 - 50 km·h^-1) during the early morning. The results revealed that broilers transported at densities of 14.1 and 15.4 birds·m^-2 recorded lower (p < 0.05) pH, water-holding capacity (WHC), and muscle redness compared to those at densities of 11.5 birds·m^-2. Furthermore, higher (p < 0.05) cooking loss was found in birds stocked at more than 14.1 birds·m^-2 compared to the other treatments. However, no effect (p > 0.05) with different crating densities on body weight loss, carcass traits, glucose, lactate, or muscle yellowness was observed. Crating density of 14.1 birds·m^-2 showed lower (p < 0.05) cortisol contents compared with birds at 10.3 and 15.4 birds·m^-2. Winter transportation had higher (p < 0.05) relative breast meat weight, cooking loss, muscle redness, and cortisol contents whereas summer transportation had higher (p < 0.05) glucose and lactate contents in the blood plasma of broilers. In conclusion, the stocking of 12.8 birds·m^-2 is recommended to minimize stress responses and undesirable changes that could negatively affect muscle quality.

• 수산해양교육연구
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• 제27권6호
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• pp.1854-1864
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• 2015

In order to analyze the pollution characteristics of small plastic debris(SPD) ashore on the shoreline of coastal flow, 12 times of survey were conducted on the Gwanganri beach of Busan for nearly 3 years. The sampled stations on the beach were divided into 11 squared survey sites from St. G1 to G11(see [Fig. 1]) and all of SPD was sorted into 11 items like P1 to P11 according to the kind of plastic materials and products(see