• Journal of the Korean Society for Precision Engineering
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• v.19 no.3
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• pp.59-65
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• 2002

In the grinding process, the degree of the sharpness in wheel grain affects the surface roughness and the dimensional accuracy. If a wheel with dull grains is used, te grinding force will be increased and the surface roughness deteriorated. To produce a precision component, the magnitude of parameters related to the wear amount of a grinding wheel has to be limited. In this study, a variation of the grinding force and the surface roughness were measured to seek the machining characteristics of the WA and CBN wheels. From the wear amount of the grinding wheel and the removal rate of workpiece, the grinding ratio was calculated. And also the wheel life was determined at a rapid decreasing point of the grinding ratio. The difference between the surface of wheel-workpiece before grinding and after wheel life was clearly verified with a microscopic photo.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.68-79
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• 1996

To investigate the efficiency of a fibrous collagen membrane(FCM) composed of bovine skin type I atelocollagen as a carrier for BMP, partially purified bovine BMP/FCM($0.3mg/10{\times}5{\times}1mm$) composites were implanted into the dorsal subcutaneous tissue of rats. FCM alone was also implanted as a control. The implants were harvested at 1, 2, 3, and 10 weeks after implantation, then prepared for routine light microscopic observation. The FCM alone did not induce osteogenesis and revealed no specific foreign body reaction nor was there any definite resorptive evidence for 10 weeks after implantation, while the BMP/FCM composites induced favorable bone formation in a process that resembled an endochondral and direct ossification mode. At 10 weeks, the well formed bone confined to embedded collagen fibers revealed hematopoietic marrow between bony trabeculae without evidence of resorptive or degenerative changes . These findings support the suggestion that BMP may induce undifferentiated mesenchymal cells into either chondroblasts or osteoblasts or both independantly according to the chemico- physical characteristics of the carrier, which develops the endochondral and/or direct bone formation process, and suggest that the FCM may be a favorable carrier for BMP.

• Journal of The Korean Association For Science Education
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• v.39 no.5
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• pp.681-694
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• 2019

This study intends to delineate the characteristics of various perspectives on the nature of science (NOS) through the textbook analysis. Thus, centering on a science textbook called Science Laboratory Experiments, this study analyzes the elements of the NOS from three different perspectives: the consensus view, features of science (FOS), and family resemblance approach (FRA). While the consensus view highlights the similar elements of the NOS across the topics, the FOS is concerned about empirical ways for doing science. The FRA rather focuses on socio-cultural aspects of science activities. While the consensus view is useful to reify the features of the NOS, the FRA helps to understand science from various viewpoints. Regarding the philosophical account for three perspectives, all of them are ambiguous to some extent. The consensus view holds contradictory dispositions e.g., relativism vs. (post-)positivism, and critical realism and instrumentalism. The FOS supports empirical tradition but cannot effectively cope with the anomalous situation. The FRA is useful to show up the ways of science in both microscopic (personal) and macroscopic (social) viewpoints. However, the broader concept about science may mislead understanding of the NOS. Consequently, this study provides some implication for improving the framework of the NOS and teaching the NOS in the classroom.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.359-366
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• 2016

The health of Alaska pollock Theragra chalcogramma seedlings was monitored during February and April 2015. After microscopic examination for parasites, 20 samples sets were made by pooling 50 individuals for each sample set. Then, they were homogenized and examined for viral and bacterial pathogens. No parasites or viruses were detected using either microscopy or PCR. Colonies suspected of belonging to the genus Vibrio were isolated from Tryptic Soya Agar and Thiosulfate Citrate Bile Salts Sucrose Agar plate incubations, and identified as Vibrio anguillarum based on biochemical and physiological examinations and PCR amplification of the 16S rDNA, recA, and pyrH genes. Although there was no mortality during the sampling period, 65.0% (13/20) of the pooled samples were PCR-positive for V. anguillarum. To prevent possible outbreaks, the pathogenic potential of V. anguillarum should be investigated in the future.

• Journal of Korean Neurosurgical Society
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• v.50 no.5
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• pp.468-471
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• 2011

Mesenchymal chondrosarcomas are rare malignant tumors of the bone and soft tissue. Spinal mesenchymal chondrosarcomas are even rarer and, to the best of our knowledge those that are concomitantly located in the intradural and extradural regions, have never been reported. We report a case of a 25-year-old man with back pain and bilateral progressive weakness of the lower extremities. Magnetic resonance imaging revealed a markedly enhanced dumbbell-shaped mass at the T7 level. The lesion was intradurally located at the left side of the spinal cord, and extended extradurally to the extraforminal space through the T7-8 intervertebral foramen. The tumor was completely excised through a posterior approach. Microscopic examination and immunohistochemical studies confirmed mesenchymal chondrosarcoma. Postoperative radiation therapy and chemotherapy were also performed to prevent local recurrence and metastasis. The patient has been symptom-free for two years after surgery. Herein, we reviewed and discussed the clinical characteristics, treatments, and outcomes of primary intraspinal mesenchymal chondrosarcomas in the literature.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.740-746
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• 2011

Thermally activated batteries have good stability, reliability and long shelf life. Due to these characteristics and operational mechanism, thermal batteries are usually applied to military power sources. Especially, Li/$FeS_2$ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as electrolytes. The electrochemistry of thermal batteries have been researched for long time, however, electrochemical study using impedance spectroscopy was not published so much. Through this research, microscopic electrochemical research was investigated with electrochemical impedance spectroscopy(E.I.S). Electrolyte effects on Li/$FeS_2$ thermal battery was researched changing electrolytes, LiCl-KCl and LiBr-LiCl-LiF. Additionally, the salts, which are added to electrolytes, effects on thermal battery were researched. It is expected that the impedance spectroscopy analysis is applicable to not only thermal battery electrochemical study effectively, but also, thermal battery developments.

• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.556-562
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• 1994

To investigate the fungal diversity in Mt. Paekwoon, higher fungi were collected in July, 1991 from the two locations of Seoul National University Forests in Kwangyang-gun, Chonnam Province. A total of 137 fungal species were collected and classified. Following six species were identified as new species unrecorded in Korea. Their morphological and taxonomic features including microscopic characteristics of spores and cystidia were also reported in this paper. Marasmius pulcherripes Peck ; Agaricus purpurellus(Moller) Moller ; Coprinus echinosporus Buller ; Xerocomus nigromaculatus Hongo ; Boletellus shichianus(Teng & Ling) Teng ; Russula kansaiensis Hongo.

• Journal of Microbiology and Biotechnology
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• v.2 no.3
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• pp.183-188
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• 1992

A soil bacterium which produces raw starch-digesting $\beta$-amylase in culture medium, has been screened from soils. One strain, isolated and identified as Bacillus polymyxa No. 26, was selected as a $\beta$-amylase producing bacterium. Morphological and biological characteristics of the strain were found to be similar to those of a strain belonging to B. polymyxa. The electron microscopic observations of the bacterial vegetative cells and sporulated cells were extensively done to know the corelation between the enzyme synthesis and sporulation. When the bacterium was cultured on the appropriate media (3% dextrin, 0.3% beef extract, 0.5% polypeptone, 1% yeast extract and 0.3% NaCl at pH 7.0 for 4 days) raw starch-digestible $\beta$-amylase was produced extracellularly. This strain produced 130 units of $\beta$-amylase per ml in a culture medium containing 3% dextrin at $30^\circ{C}$. This value is compared to those of other $\beta$-amylase-producing strains. The optimum pH and temperature for crude enzymes were pH 6.5 to 7.0 and $50^\circ{C}$, respectively. The enzymes were stable between pH 5.5 and 9.0 for 30 min at $45^\circ{C}$.

• Microbiology and Biotechnology Letters
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• v.1 no.1
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• pp.3-11
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• 1973

The biochemical characteristics of Astradix -P, isolated from Astragalus membranaceus Bunge as yeaststatic substance, were reported on a previous paper. And on this report, some relation to the nitrogen metabolism of yeast was studied. Inorganic or organic source of nitrogen easily uptaking yeast did not show any antagonistic action to the inhibitory action of Astradix -P on the yeast growth. Especially an organic nitrogen source, arginine, histidine and lysine, classified to basic amino acid, was reacted as an antagonistic substance to the sample. But, ornithine, a basic amino acid, did not show any antagonistic action to the sample. In the mixed media containing neutral and acidic amino acids as a nitrogen source, yeast growth was inhibited strongly. If the basic amino acid was added to the same mixed media, the yeast growth was not inhibited by Astradix-P therefore, the antagonistic action of basic amino acid to the Astradix-p was readily observed. The yeast static action of Astradix-P was partially related to the isoelectric point of amino acid as a nitrogen source. Yeast cells which propagated under the media containing growth inhibitor, Astradix -p, did not bring any remarkable denaturation of cell structure by electro-microscopic observation.

• Childhood Kidney Diseases
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• v.22 no.2
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• pp.75-80
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• 2018

Nutcracker syndrome is a phenomenon that the left renal vein (LRV) is pressed between the superior mesenteric artery (SMA) and the aorta. Clinical characteristics include gross or microscopic hematuria, orthostatic proteinuria, abdominal pain, and back pain. It occurs due to LRV squeezing caused by narrowed aortomesenteric angle. SMA syndrome is a disease that the third part of the duodenum is prone to intestinal obstruction by narrowed angle between the SMA and the abdominal aorta. Clinical symptoms include postprandial abdominal distension, epigastric pain, nausea, and vomiting. SMA syndrome and nutcracker syndrome have common features that result from narrowed aortomesenteric angle. However, it is very rare for both syndromes to occur simultaneously, so the two syndromes are regarded as separate diseases. This is a report on a case of nutcracker syndrome with SMA syndrome in a child who presented gross hematuria, recurrent abdominal pain and vomiting. To our knowledge, nutcracker syndrome simultaneous with SMA syndrome has not been previously reported in pediatric patient, especially with an exhibition of gross hematuria. This case suggests that the simultaneous presence of SMA syndrome with the same pathogenesis needs to be considered when nutcracker syndrome is suspected in pediatric patients with hematuria.