• Korean Journal of Materials Research
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• v.8 no.4
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• pp.328-336
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• 1998

In metal-carbon system with no mutual solubility between matrix and alloying elements as solid or liquid phases, Cu-C-X nanocomposite metal powders were prepared by high energy ball milling for solid-lubricating bronze bearings. Elemental powder mixtures of Cu-lOwt.%C- 5wt. %Fe and Cu- lOwt. %C- 5wt. %Al were mechanically alloyed with an attritor in an argon atmosphere, and then microstructural evolution of the Cu-C-X nanocomposite metal powders was examined. It has been found that after 10 hours of MA, the approximately 10$\mu\textrm{m}$ sized Cu-C- X nanocomposite metal powders can be produced in both compositions. Morphological characteristics and microstructural evolution of the Cu-C-X powders have shown a similar MA procedure compared to those of metal-metal system. As a result of X - ray diffraction analysis, diffraction peaks of Cu and C were broaden and peak intensities were decreased as a function of MA time. Especially, the gradual disappearance of C peaks in the X- ray spectra is proved to be due to the lower atomic scattering factor of C. The calculated Cu crystallite sizes in Cu- C- X nanocomposite metal powders by Williamson- Hall equation were about lOnm size, on the other hand, the observed ones by TEM were in the range of 10 to 30nm.

• Childhood Kidney Diseases
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• v.14 no.1
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• pp.32-41
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• 2010

Purpose : Glomerulonephropathy (GN) often manifests as proteinuria and progresses to chronic renal failure without specific therapy. Mesenchymal stem cell (MSC) has been tried as a therapeutic agent in experimental GN, and previous studies showed that administration of MSC concomitantly to the insult inducing GN or via intra-renal administration ameliorated proteinuria. The purpose of this study was to test the therapeutic potential of MSC administered via intravenous route at the time of clinically evident proteinuria. Methods : MSCs were administered intravenously via tail vain into the mice with adriamycin (ADR) induced nephropathy (ADR-GN), two weeks after ADR injection when massive proteinuria was evident. To test the capacity of MSC modulate the cytokine production in the inflammatory milieu, the concentrations of IFN-$\gamma$ and IL-10 were measured in the supernatant of in vitro mixed lymphocyte culture (MLC) with or without additional MSC. Results : MSCs administered intravenously into the proteinuric mice with ADR-GN accelerated the recovery of this experimental GN with disappearance of proteinuria in two weeks when the saline treated (control) mice still showed significant proteinuria. The mice treated with MSC also had a tendency of better survival. Addition of MSC decreased IFN-$\gamma$ and increased IL-10 in the supernatant of MLC. Conclusion : This study showed that MSC had a therapeutic potential even when administered in a more clinically relevant setting into a proteinuric glomerulonephropathy model. Further study to verify the mechanism and long-term safety of this phenomenon is required.

• Journal of Life Science
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• v.26 no.2
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• pp.164-173
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• 2016

Isotocin (IT), a nonapeptide homolog of oxytocin in mammals, has been suggested to be involved in physiological processes including social behaviors, stress responses, and osmoregulation in teleost fish. To study its structure and function, the gene encoding the IT precursor was cloned from the genomic DNA and brain cDNA of the cinnamon clownfish, Amphiprion melanopus. The IT precursor gene consists of three exons separated by two introns, and encodes an open reading frame of 156 amino acid (aa) residues, comprising a putative signal peptide of 19 aa, a mature IT protein of 9 aa, a proteolytic processing site of 3 aa, and 125 aa of neurophysin. Tissue-specific analysis of the IT precursor transcript indicated its expression in the brain and gonads of A. melanopus. To examine its osmoregulatory effects, the salinity of the seawater (34 ppt) used for rearing A. melanopus was lowered to 15 ppt. Histological analysis of the gills indicated the apparent disappearance of an apical crypt on the surface of the gill lamella of A. melanopus, as pavement cells covered the surface upon acclimation to the lower salinity. The level of Na⁺/K^+-ATPase activity in the gills was increased during the initial stage of acclimation, followed by a decrease to its normal level, suggesting its involvement in osmoregulation and homeostasis. The only slight increase in the level of IT precursor transcript in the A. melanopus brain upon low-salinity acclimation suggested that IT played a minor role, if any, in the process of osmoregulation.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.34 no.4
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• pp.26-36
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• 2016

This study aims to identify the place and location of Gasan around Cheonggyecheon in the Joseon Dynasty, and also to examine the current status of their changes or disappearance in the process of modernization. On top of literature research on old document and maps related to dredging of Cheonggyecheon, the field survey to understand the actual status and location of Gasan was conducted. The study contents are like below. First, through old document and maps related to Cheonggyecheon in the Joseon Dynasty, the contents and records related to Gasan around Cheonggyecheon were selected. Such Gasan were mainly built up by dredging work of branch/streamlet in the era of King Sejong, and also the large-scale dredging during the period of King Yeongjo. Second, the location of Gasan and forest around Cheonggyecheon shown in old maps was understood. With Ogansumun(Five-arched Floodgates) as the center, they were constructed on both hills of Cheonggyecheon inside/outside of the capital city, and its surrounding branches. Third, based on the measures to create a scale map based on Susunjeondo, the location of Gasan on old maps was found on the current map, and then the current status of places expressed as Gasan was surveyed. In the results of the study, even though most of the Gasan built up around Cheonggyecheon in the Joseon Dynasty have disappeared by the urban development performed since the end of 19th century, still, there are some remains left.

• Journal of Yeungnam Medical Science
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• v.12 no.2
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• pp.319-330
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• 1995

The influence of normal late pregnancy on insulin action and insulin secretion was studied in the Sprague-Dawley female rats. On 20th day after mating, intravenous glucose tolerance test(IVGTT) was performed in non pregnant control and pregnant rats. As results of IVGTT, glucose disappearance rate was not significantly different in both groups, but secretory response of insulin was significantly(p<0.05) increased in pregnant rat. And the ratio of insulin/glucose was significantly higher in pregnant rats, which means existence of insulin resistance. These insulin resistance was overcomed by increased secretory response of pancreatic insulin. Insulinogenic index(${\Delta}$ insulin/glucose - 5 min) was highly significantly (r=0.62, p<0.01) correlated with progesterone concentration. Glycogen level and amounts of $^{14}C$-glucose incorporated into glycogen after IVGTT were significantly(p<0.05) decreased in the liver, but were not changed significantly in soleus. Glycogen synthase activity of soleus and liver was not differ significantly in the both groups. Insulin binding at varying concentrations of insulin to crude membrane of pregnant liver was not significantly different from control. In conclusions, although these pregnant rats were normal glucose tolerance due to increased secretory response of insulin, that was correlated with progesterone concentration, pregnant rat had insulin resistance. The mechanisms of insulin resistance were not related to defect of insulin binding phase and glycogen synthase, but suggest pre-receptor and/or postreceptor phase.

• Korean Journal of Remote Sensing
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• v.11 no.3
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• pp.83-100
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• 1995

The land-use has changed rapidly during the last two decades in accordance with urbanization in the Seoul Metropolitan Region. As a result of these changes, the local climate has undergone changes as well. This study intends to define the land-use changes, and then to show how they have brought in significant changes in the local climates. Land-use changes in the study area so repidly that up-to date maps and documents are not available at present. Therefore, Landsat data for land-use classification and NOAA AVHRR thermal data for the temperature fields were analyzed. Additionary, to visualize the effect of the land-use on the local climate, computer-enhanced brightness temperatures, Green Belt and city boundaries were overlaid on land-use patterns obtained from satellite images using GIS techniques. The results of analysis demonstrate that Green Space in the Seoul Metropolitan Region decreased from 94% to 62% while urban land-use increased ten times, from 4% to 39% for the period of 1972-1992. The resulting disappearance of biomass caused by land-use changes may have implications for the local-and micro-climate. The results show that the local climate of the study area became drier and warmer. This study also suggests a need for further studies of man's effects on local climate to minimize adverse influences and hazardous pollution and efficacious ways for urban planning.

• Bulletin of the Korean Chemical Society
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• v.15 no.11
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• pp.961-966
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• 1994

Oligomerization of phenylacetylene is catalyzed by $Rh(ClO_4)(CO)(PPh_3)_2$ (Rh-1), $[Rh(CO)(PPh_3)_3]ClO_4$ (Rh-2), $[Rh(COD)L_2]ClO_4 (L_2=(PPh_3)_2$, Rh-3; $(PPh_3)(PhCN)$, Rh-4; $(PhCN)_2$, Rh-5), $[Rh(C_3H_5)(Cl)(CO)(SbPh_3)_2]ClO_4$ (Rh-6), $[Ir(COD)L_2]ClO_4 (L_2=(PPh_3)_2$, $Ir-1; (PPh_3)(PhCN)$, $Ir-2; (PhCN)_2$, Ir-3; (AsPh_3)(PhCN)$, $Ir-4; Ph_2PCH_2CH_2PPh_2$, Ir-5; COD, Ir-6 and 2,2'-dipyridyl, Ir-7), $Ir(ClO_4)(CO)(PPh_3)_2$, $Ir-8, [Ir(PhCN)(CO)(PPh_3)_2]ClO_4$, Ir-9 to produce dimerization products, 1,3-diphenylbut-1-yn-3-ene, 1, (E)-1,4-diphenylbut-1-yn-3-ene, 2 and (Z)-1,4-diphenylbut-1-yn-3-ene, 3, and cyclotrimerization products, 1,3,5-triphenylbenzene, 4 and 1,2,4-triphenylbenzene, 5. Product distribution of the oligomers varies depending on various factors such as the nature of catalysts, reaction temperature, counter anions and excess ligand present in the reaction mixtures. Increasing reaction temperature in general increases the yield of the cyclotrimerization products. Exclusive production of dimer 1 and trimer 4 can be obtained with Ir-1 at 0 $^{\circ}$C and with Ir-2 in the presence of excess PhCN (or $CH_3CN$) at 50 $^{\circ}$C, respectively. Dimer 2 (up to 81%) and trimer 5 (up to 98%) are selectively produced with Rh-1 at 50 and 100 $^{\circ}$C respectively. Production of 3 is selectively increased up to 85% by using $PF_6$- salt of $[Ir(COD)(PPh_3)_2]$+ at 25 $^{\circ}$C. Addition of $CH_3I$ to Rh-1 produces $CH_3PPh_3^+I-$ and increases the rate of oligomerization(disappearance of phenylacetylene). Among the metal compounds investigated in this study, Ir-1 catalyzes most rapidly the oligomerization where the catalytically active species seems to contain lr(PPh3)2 moiety. The stoichiometric reaction of phenylacetylene wth Ir-9 at 25 $^{\circ}$C quantitatively produces hydridophenyl-ethynyl iridium(III) complex, $[lr(H)(C{\equiv}CPh)(PhCN)(CO)(PPh_3)_2]ClO_4$ (Ir-11), which seems to be an intermediate for the oligomerization.

• International Area Studies Review
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• v.20 no.2
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• pp.113-140
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• 2016

This paper first extracts the main basis for the Middle-Income Trap(MIT) to apply these grounds to reality of the Chinese economy. And then confirmed crisis factors of China economy. Also discussed then the economic reforms of China in order to not fall into the MIT. After reviewing previous research extracted six factors the results will correspond to comply with the Chinese economy. Those are 'Over-investment', 'excess capacity' 'reduction of TFP continued,' 'disappearance and the aging of the population bonus', 'excessive debt and structural adjustment and financial instability of the company', 'income unequal expansion', 'low financial and information infrastructure accessibility', and 'low transparency index'. China's policy direction to avoid the MIT generally set properly, but proof that implementation process not easy, was appearing everywhere. After all, China economy should be modified now to a reforms of 'government failure' and promotion of function for ongoing restructuring system in the market. Because of the SDR incorporation from 2015, it is inevitable to face major constraints in the external aspects.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.691-699
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• 2021

The global surface temperature has risen critically over the past century and according to the IPCC Fifth Assessment Report 2014, existing risks in natural and human systems will worsen. Coastal erosion is mostly caused by climate change and among all the coastal areas at risk, Benin, which is part of the Gulf of Guinea, has been ranked very highly as a vulnerable region. Therefore, in this review, we focus on the evolution of coastline change in Cotonou of Benin, summarizing its resultant impacts and applied measures around the coast area by reviewing previous studies. Signs of coastal erosion in Cotonou appeared in 1963. After 39 years, the east shoreline of Cotonou has retreated by 885 m, resulting in the disappearance of more than 800 houses. To solve this problem, Benin authorities built seven groynes in 2013, and have increased the number of the structure as a way to interrupt water flow and limit the movement of sediment. Over the region, shorelines appeared preserved accordingly. In contrast, areas located further east, where groynes were not installed, have suf ered from intensive erosion at a rate of 49 m/yr. In the future, as a next step, the effectiveness of groynes should be studied with local and broader perspectives.

• Laboraroty Animal Research
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• v.34 no.4
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• pp.166-175
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• 2018

Recombination activating gene-2 (RAG-2) plays a crucial role in the development of lymphocytes by mediating recombination of T cell receptors and immunoglobulins, and loss of RAG-2 causes severe combined immunodeficiency (SCID) in humans. Rag-2 knockout mice created using homologous recombination in ES cells have served as a valuable immunodeficient platform, but concerns have persisted on the specificity of Rag-2-related phenotypes in these animals due to the limitations associated with the genome engineering method used. To precisely investigate the function of Rag-2, we recently established a new Rag-2 knockout FVB mouse line ($Rag-2^{-/-}$) manifesting lymphopenia by employing a CRISPR/Cas9 system at Center for Mouse Models of Human Disease. In this study, we further characterized their phenotypes focusing on histopathological analysis of lymphoid organs. $Rag-2^{-/-}$ mice showed no abnormality in development compared to their WT littermates for 26 weeks. At necropsy, gross examination revealed significantly smaller spleens and thymuses in $Rag-2^{-/-}$ mice, while histopathological investigation revealed hypoplastic white pulps with intact red pulps in the spleen, severe atrophy of the thymic cortex and disappearance of follicles in lymph nodes. However, no perceivable change was observed in the bone marrow. Moreover, our analyses showed a specific reduction of lymphocytes with a complete loss of mature T cells and B cells in the lymphoid organs, while natural killer cells and splenic megakaryocytes were increased in $Rag-2^{-/-}$ mice. These findings indicate that our $Rag-2^{-/-}$ mice show systemic lymphopenia with the relevant histopathological changes in the lymphoid organs, suggesting them as an improved Rag-2-related immunodeficient model.