• Journal of Biomedical Engineering Research
• /
• v.20 no.1
• /
• pp.37-44
• /
• 1999

Because of bone resorption, wear of ultra-high molecular weight polyethylene(UHMWPE) in total knee arthroplasty has been recognized as a major factor in long-term failure of knee implant. The surface damage and the following harmful wear debris of UHMWPE is largely related to contact stress. Most of the previous studies focused on the contact condition only at the articulating surface of UHMWPE. Recently, contact stress at the metal-backing interface has been implicated as one of major factors in UHMWPE wear. Therefore, the purpose of the is study is to investigate the effect of the contact stress for different thickness, conformity friction coefficient, and flexion degree of the UHMWPE component in total knee system, considering the contact conditions at both interfaces. In this study, a two-dimensional non-linear plane strain finite element model was developed. The results showed that the maximum value of von-Mises stress occurred below the articulating surface and the contact stress was lower for the more conforming models. All-polyethylene component showed lower stress distribution than the metal-backed component. With increased friction coefficient on the tibiofemoral contact surface, the maximum shear stress increased about twofold.

• Korean Journal of Environmental Biology
• /
• v.31 no.4
• /
• pp.402-410
• /
• 2013

In this study, to identify ichthyofauna of the Seomjin River, which has no barrage at estuary, and to estimate effect of estuary barrage, fish sampling was conducted at 16 study sites in mainstream of the Seomjin River from 2010 to 2012. A total of 54 species classified into 17 families were collected. Cyprinidae was the dominant family and Zacco platypus (relative abundance, RA: 47.8%) was identified as the dominant species. In total, 17 Korean endemic species (31.5%) were collected, and it is higher than the average endemic rate of Korean peninsula (22.5~25.9%). Although the relative abundance of exotic species (1.1%) was low, it is higher than the past studies (2002: 0.0%, 2009: 0.4%). Dominance index of freshwater region (St.4~St.16) was relatively higher than estuary (St.1~St.3), because Z. platypus showed high relative abundance at freshwater region. But diversity and evenness index showed contradictory results, as estuary was higher than freshwater region. The ratios of sea fish, peripheral freshwater fish and economic fish, and diversity index are higher than the Nakdong River, the Yeongsan River and the Geum River. In conclusion, to conserve the value of the Seomjin River ichthyofauna, continuous monitoring is necessary.

• The Korean Journal of Pesticide Science
• /
• v.10 no.4
• /
• pp.335-343
• /
• 2006

Five strains of Korean entomopathogenic nematodes(EPN), steinernematids and heterorhabditids(Steinernama carpocapsae GSN1, Steinernema sp. GSNUS-10, Steinernama sp. GSNUS-14, Heterorhabditis bacteriophora Hamyang, Heterorhabditis sp. GSNUH-1) were evaluated and tried in petri dish, pot, and vegetable greenhouses for environmentally friendly control of beet armyworm, Spodoptera exigua. $LC_{50}$ values of five EPN strains against beet armyworm was different depending on nematode strain and beet armyworm instar. $LC_{50}$ value of Steinernema carpocapse GSN1(GSN1) was 3.8-5.1 infective juveniles(Ijs) in 2nd to 4th instars of beet armyworm. Pathogenicity of five EPN strains against beet armyworm different in nematode strain, concentration, application times, and vegetable species in pot and greenhouse. Steinernema spp. was more effective than Heterorhabditis spp. against beet armyworm. Two or three times of applications of EPN were found to be effective regardless of nematode strain and concentration in pot and greenhouse. ENP showed different reactions on vegetable species. Efficacy of EPN was higher on Chinese cabbage than that on cabbage and kale. GSN1 was one of the most effective nematodes and 100,000 infective juveniles per $m^2$(720,000 Ijs/$7.2m^2=1{\times}10^9$Ijs/ha) resulted in higher mortality in greenhouse.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.13 no.5
• /
• pp.412-418
• /
• 2020

This paper produced an automatic fluid management system that can accurately control the specific gravity of etching solution(FeCl₃), and produced a SUS MASK applied to OLED. The target was set at 0.4 mm in diameter of the hole. As a result of this misconception, the etching speed increased when the specific gravity(S.G) value of FeCl₃ was changed from 1.43 to 1.49. And when the weight was 1.49, it was found that the vertical diameter was 0.405 mm, approaching the target. When pressure injection was varied from 2.0kg/cm2 to 3.5kg/cm2, the hole diameter at 3.0 kg/cm2 averaged 0.4mm, matching the target. The characteristics of the change in gravity were analyzed by applying the additive 1.2% and setting the weight at 1.430 by mixing HCl and H2O in FeCl₃ and fixing the injection pressure at 3.0 kg/cm2. When the weight changed from 1.460 to 1.469 the etching speed increased from 0.564 to 0.540. When the weight was 1.467, the hole diameter was measured at 0.4 mm and the target was reached.

• Journal of Mushroom
• /
• v.18 no.2
• /
• pp.151-163
• /
• 2020

Antioxidant activities and contents of β-glucan and amino acids of wild mushrooms collected from Geosan, Boeun, Eumseong, and Bonghwa in Korea were investigated. Phaeolus schweinitzii (OK1165) displayed the highest 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (60.3%), ferric reducing antioxidant power (3.84), reducing power (1.05), nitrite scavenging activity (96.4%), total polyphenol content (54.7 mg gallic acid equivalent/g), and flavonoid content (19.98 mg quercetin equivalent/g). The β-glucan content of Pycnoporus cinnabarinus (OK1172) of 51.9% was higher than the contents of the other mushrooms. P. schweinitzii (OK1165) displayed the highest total amino acid (1,373.9 mg/kg) and essential amino acid (515.0 mg/kg) contents among the wild mushrooms. The findings confirmed that wild mushrooms could be a high-value resource for functional foods with pronounced antioxidant activity. The results also provide fundamental data for extracting useful compounds from wild mushrooms.

• Korean Journal of Pharmacognosy
• /
• v.36 no.3 s.142
• /
• pp.164-170
• /
• 2005

In the present study, we investigated the mineral and metabolite composition and antioxidant activities in the flower, stem and root of Aster ciliosus Kitamura in order to detect biologically active substances and develop novel functional resources. The mineral and metabolite compositions differ significantly among the organ of Aster ciliosus Kitamura. The flower is composed of K as 827 mg/100g. while the stem and root are composed of Na as 654.64mg/100g and 771.70mg/100g, respectively. Contents of unsaturated fatty acids, such as oleic, linoleic, and linolenic acid, were higher than those of saturated fatty acid, such as palmitic acid in flower. The contests of phenolic compounds were measured at 285 nm using different solvents: 2.53 and 2.03 optical density (OD) in chloroform and 1.864 and 1.715 in ethanol extracts for the stem and root, respectively. Antioxidant activity was measured in 75% ethanol extracts: 41.3, 42.0 and $45.2\;{\mu}g/ml$ in stem, root and flower at $IC_{50}$ value, respectively. These results suggest that extracts from Aster ciliosus Kitamura can be potentially used as novel resources for antioxidant and biological active substances.

• Journal of Biomedical Engineering Research
• /
• v.27 no.5
• /
• pp.203-209
• /
• 2006

The aim of this study is to investigate the feasibility of ex vivo MR diffusion tensor imaging technique in order to observe the diffusion-contrast characteristics of human gastric tissues. On normal and pathologic gastric tissues, which have been fixed in a polycarbonate plastic tube filled with 10% formalin solution, laboratory made 3D diffusion tensor Turbo FLASH pulse sequence was used to obtain high resolution MR images with voxel size of $0.5{\times}0.5{\times}0.5mm^3\;using\;64{\times}32{\times}32mm^3$ field of view in conjunction with an acquisition matrix of $128{\times}64{\times}64$. Diffusion weighted- gradient pulses were employed with b values of 0 and $600s/mm^2$ in 6 orientations. The sequence was implemented on a clinical 3.0-T MRI scanner(Siemens, Erlangen, Germany) with a home-made quadrature-typed birdcage Tx/Rx rf coil for small specimen. Diffusion tensor values in each pixel were calculated using linear algebra and singular value decomposition(SVD) algorithm. Apparent diffusion coefficient(ADC) and fractional anisotropy(FA) map were also obtained from diffusion tensor data to compare pixel intensities between normal and abnormal gastric tissues. The processing software was developed by authors using Visual C++(Microsoft, WA, U.S.A.) and mathematical/statistical library of GNUwin32(Free Software Foundation). This study shows that 3D diffusion tensor Turbo FLASH sequence is useful to resolve fine micro-structures of gastric tissue and both ADC and FA values in normal gastric tissue are higher than those in abnormal tissue. Authors expect that this study also represents another possibility of gastric carcinoma detection by visualizing diffusion characteristics of proton spins in the gastric tissues.

• Journal of Korean Philosophical Society
• /
• v.126
• /
• pp.159-190
• /
• 2013

Feminist critics have criticized Aristotle as a sexist, misogynist, male chauvinist or masculinist, or, at least, their chief spokesman. Indeed, he says in the Politics that the male is by nature superior to the female and, also, that women possess the same deliberative part of the soul as men, but without authority, etc. In the Generation of Animals, he claims that the male supplies the form and the efficient cause, whereas the female supplies the material cause only in reproduction and describes the female as a mutilated being. When these remarks of Aristotle are read without considering their overall context, it hardly seems possible for him to escape from such severe criticism and condemnation. On the contrary, in what follows, I shall claim that the criticism and condemnation that has been ascribed to him is unfair. Although it is undeniable that Aristotle has made such remarks, it does not immediately follow that he was a sexist. In particular, I shall show his view on the status of men and women by analysing the value of matter and form ascribed in two of his main philosophical theories, the theories of hylomorphism and four causes. In consequence, we shall arrive at the conclusion that, since the theories do not imply the significance or necessity of either form or matter alone, but of both, there is no sign of sexism or misogyny or male chauvinism in Aristotle.

• Korean Journal of Environment and Ecology
• /
• v.32 no.6
• /
• pp.591-602
• /
• 2018

Clithon retropictus has been designated as an endangered wildlife Class II due to its high value as a biological indicator species capable of judging environmental quality such as salinity, water flow, and ground conditions. However, basic research on its physiological and ecological characteristics is still lacking. As such, this study intended to examine the impact of environmental conditions such as salinity and soil particle size on the size and density of Clithon retropictus at the Yeoncho river estuary. The investigation of the salinity, which is a key variable that affects the distribution of organisms in the estuary, showed that Clithon retropictus could grow at a salinity ranging from 0#x2030; (freshwater) to 25‰ (brackish water). The coarse gravel (19-75mm) tended to increase nearer the upper stream (under the Yeoncho weir), while the proportion of particles smaller than sand (less than 19mm) increased toward the downstream. The population and the size of the individuals decreased rapidly in the downstream where water stagnated near the Yeoncho weir, and the salt water joined. The results indicated that Clithon retropictus had a high tolerance to salinity, but the adaptability was weaker toward the extremes since the population, and the size tended to decrease as the salinity increased. The correlation analysis revealed that both salinity and soil particle size affected the population and individual size. The correlation between the individual size and salinity was -0.242 (P <0.01), indicating that the size decreased with increasing salinity. The correlation between individual size and coarse gravel having a particle size of 19mm or more was 0.420 (P <0.01), indicating that the size increased with increasing the particle size.

• Journal of Korean Society of Water and Wastewater
• /
• v.32 no.6
• /
• pp.487-497
• /
• 2018

Water quality improvement processes for stagnant area consist mainly of technologies applying vegetation and artificial water circulation, and these existing technologies have some limits to handle pollution loads effectively. To improve the purification efficiency, eco-friendly technologies should be developed that can reinforce self-purification functions. In this study, a multi-functional floating island combined with physical chemical biological functions ((1) flotation and oxidization using microbubbles, (2) vegetation purification and (3) bio-filtration with improved adsorption capacity) has been developed and basic experiments were performed to determine the optimal combination conditions for each unit process. It has been shown that it is desirable to operate the microbubble unit process under conditions greater than $3.5kgf/cm^2$. In vegetation purification unit process, Yellow Iris (Iris pseudacorus) was suggested to be suitable considering water quality, landscape improvement and maintenance. When granular red-mud was applied to the bio-filtration unit process, it was found that T-P removal efficiency was good and its value was also stable for various linear velocity conditions. The appropriate thickness of filter media was suggested between 30 and 45 cm. In this study, the optimal design and operating parameters of the multi-functional floating island have been presented based on the results of the basic experiments of each unit process.