• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.22 no.1
• /
• pp.5-10
• /
• 2012

In general, the fabrications of the LEDs with mesa structure are performed grown by MOCVD method. In order to etch and separate each chips, the LEDs are passed the RIE and scribing processes. The RIE process using plasma dry etching occur some problems such as defects, dislocations and the formation of dangling bond in surface result in decline of device characteristic. The SAG method has attracted considerable interest for the growth of high quality GaN epi layer on the sapphire substrate. In this paper, the SAG method was introduced for simplification and fabrication of the high quality epi layer. And we report that the size of selective area do not affect the characteristics of original LED. The diameter of SAG circle patterns were choose as 2500, 1000, 350, and 200 ${\mu}m$. The SAG-LEDs were measured to obtain the device characteristics using by SEM, EL and I-V. The main emission peaks of 2500, 1000, 350, and 200 ${\mu}m$ were 485, 480, 450, and 445 nm respectively. The chips of 350, 200 ${\mu}m$ diameter were observed non-uniform surface and resistance was higher than original LED, however, the chips of 2500, 1000 ${\mu}m$ diameter had uniform surface and current-voltage characteristics were better than small sizes. Therefore, we suggest that the suitable diameter which do not affect the characteristic of original LED is more than 1000 ${\mu}m$.

• Clinical and Experimental Pediatrics
• /
• v.53 no.1
• /
• pp.28-32
• /
• 2010

Purpose : Although eosinophilia is a common laboratory finding in many neonatal intensive care units (ICUs), its causative mechanisms remain obscure. We aimed to determine the causes of eosinophilia in the neonatal ICU environment. Methods : Serial eosinophil counts were determined weekly for 288 hospitalized, appropriately grown neonates. Infants were divided into four groups according to gestational age, and the incidence and etiologic factors of eosinophilia were retrospectively studied. Results : Absolute eosinophilia (>$700/mm^3$) was documented in 18% (52/288) of neonates. Twenty-two infants (42.3%) exhibited mild eosinophilia ($700-999cells/mm^3$), 27 (51.9%) exhibited moderate eosinophilia ($1,000-2,999cells/mm^3$), and 3 (5.8%) exhibited severe eosinophilia (>$3,000cells/mm^3$). Of the 288 infants studied, 54 suffered sepsis. Thirty of these 54 infants (55.6%) showed eosinophilia, and 22 out of the remaining 234 infants (9%) without sepsis showed eosinophilia, indicating that eosinophilia was more prevalent in the sepsis group (P <0.05). All 5 infants suffering from bronchopulmonary dysplasia showed eosinophilia, and 47 out of the remaining 283 infants (16.7%) without bronchopulmonary dysplasia showed eosinophilia. Thus, eosinophilia was more prevalent in the bronchopulmonary dysplasia group (P<0.05). Furthermore, increased prevalence of eosinophilia was associated with respiratory distress syndrome, ventilator use, blood transfusion, and total parenteral nutrition (P<0.05). Conclusion : Our results suggest that eosinophilia is influenced by sepsis and bronchopulmonary dysplasia, although it can also occur idiopathically at birth. Moreover, the potential role of eosinophils in conditions such as wound healing and fibrosis in sepsis or chronic lung disease may be a cause of eosinophilia.

• Korean Journal of Ecology and Environment
• /
• v.49 no.2
• /
• pp.102-109
• /
• 2016

The sustainability of Iris koreana, a rare and endemic plant designated by the Korea Forest Service, is threatened due to artificial factors such as habitats loss and climate change etc. and internal factors such as changes in biological properties of the habitats etc. but conservation biology research has not been performed in South Korea. The objective of this study is to establish the species conservation strategies by analyzing the characteristics of their habitats, including: 1) Population characteristics, and 2) habitat analysis of the vegetation and abiotic environments. From April to May, 2015, population characteristics [density (stems $m^{-2}$), flowering rate (%) and leaf area size ($cm^2$)] in I. koreana habitats such as Buan1~6 (BA1~6), Jangseong1~2 (JS1~2) and vegetation characteristics (phytosociological research and ordination analysis), and abiotic environments [soil temperature ($^{\circ}C$), soil humidity (%), transmitted light ($mol{\cdot}m^{-2}{\cdot}d^{-1}$) and canopy openness (%)] were measured. I. koreana was mainly distributed at elevation 50 to 150 m and 2 to $11^{\circ}$ slope. Slope direction was shown as 90 to $193^{\circ}$. The average degree of canopy openness was 11.9%. It showed the highest at BA2 (17.5) and the lowest at JS1 (7.7). The average degree of transmitted light was $6.3mol{\cdot}m^{-2}{\cdot}d^{-1}$. It showed the highest at BA2 (10.1) and the lowest at JS1 (3.6). Population density showed average 25.8 (stems $m^{-2}$). It showed the highest at JS2 (19.7) and the lowest at JS1 (9.3). flowering stems showed average 16.9 (stems). It showed the highest at BA3 (35) and the lowest at BA5 (4). Leaf area size was average $94.1cm^2$.

• Spatial Information Research
• /
• v.18 no.4
• /
• pp.43-53
• /
• 2010

A dam is effective in stable supply of water required in daily life and reduction of damage from floods. hut a lot of land or houses arc submerged due to the construction of a darn heavily affecting environment in surrounding areas. In order to improve and support daily life environment. surrounding a dam, many projects have been conducted. and the study has focused on analyzing bow to calculate error characteristics of scale effect for submerged area by using GIS spatial overlay. First, as a result of areal error in submerged area by scale based on a 1/3,000 digital topographic map, it was found that the 1/5,000 digital topographic map is 9.5 times, 9.0 times and 10.5 times more accurate than the 1/25,000 digital topographic map, respectively, in the total of areal error, standard error and areal error for submerged area. Second, as a result of analysis on areal error in areas surrounding a dam, it has been found that Jinan-eup in Jinan-gun registered the largest difference in area within 2km and 2~5km catchment area by recording 13.8 times and 20.6 times, respectively, in the 1/5,000 digital topographic map compared to the 1/25,000 digital topographic map. In addition, in areas out of catchment area within 2km, the area of occupation was very small, so there were no characteristics in error. The out of catchment area, Nami-myeon in Geumsan-gun recorded the largest errors of 31.8 times. Finally, it was found that the ratio of the total areal error in area surrounding a dam, standard error and the total areal error in the entire area using 1,5000 digital topographic map is 7.4 times, 11.8 times and 7.4 times more accurate than the 1/25,000 digital topographic map.

• Journal of Hospice and Palliative Care
• /
• v.8 no.2
• /
• pp.152-155
• /
• 2005

Purpose: The lower extremity edema (LEE) is a common distressful symptom in advanced cancer patients and is hard to manage. We analyze the characteristics of LEE in patients with advanced cancer to provide the basic information of causes and adequate management. Methods: Physical examination, assessment of the location and severity of edema, blood chemistry (albumin, creatinine), Doppler Sono for patients with suspecting deep vein thrombosis (DVT), and abdomen CT scan for patient with suspecting lymph edema were performed. Severity of edema was classified according to NCI lymph edema scaling and improvement was defined as lowering at least 1 grade of edema after management. Results: Among 154 patient who had been admitted to Hospice Ward from Mar 2003 to Jan 2004, 33 had LEE, and 6 had both upper extremity edema and LEE except generalized edema. Their underlying cancers were stomach (7), lung (6), biliary tract (5), liver (5), colorectal (5), pancreas (2), and others (9). There were 12 patient with grade I, 20 patients with grade II, and 7 patients with grade III edema. The causes were hypoalbuminemia (11), lymph edema (10), DVT (7), obstruction of inferior vena cava (IVC) or portal vein (6), and dependent edema (5). The common managements were including leg elevation and diuretics. Elastic stocking was applied for patients with DVT and leg massage and pneumatic compression was used for lymph edema. The 2/3 patients were improved after management. Conclusion: The incidence of LEE in terminal cancer pts was high (25.3%) and their causes were variable including lymph edema, DVT, hypoalbuminemia and dependent edema. Active noninvasive management according to causes could result in good palliation.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.16 no.2
• /
• pp.81-86
• /
• 2012

Purpose : Combined MR/PET scanners that use the MRI for PET AC face the challenge of absent surface coils in MR images and thus cannot directly account for attenuation in the coils. To make up for the weak point of MR attenuation correction, Three Modality System (PET/CT +MR) were used in Severance hospital. The goal of this work was to investigate the effects of MR Torso Coil on CT attenuation correction for PET. Materials and Methods : PET artifacts were evaluated when the MR Torso Coil was present of CTAC data with changing various kV and mA in uniformity water phantom and 1994 NEMA cylinderical phantom. They evaluated and compared the following two scenarios: (1) The uniform cylinder phantom and the MR Torso Coil scanned and reconstructed using CT-AC; (2) 1994 NEMA cylinderical phantom and the MR Torso Coil scanned and reconstructed using CT-AC. Results : Streak artifacts were present in CT images containing the MR Torso Coil due to metal components. These artifacts persisted after the CT images were converted for PET-AC. CT scans tended to over-estimate the linear attenuation coefficient when the kV and mA is increasing of the metal components when using conventional methods for converting from CT number. Conclusion : The presence of MR coils during PET/CT scanning can cause subtle artifacts and potentially important quantification errors. Alternative CT techniques that mitigate artifacts should be used to improve AC accuracy. When possible, removing segments of an MR coil prior to the PET/CT exam is recommended. Further, MR coils could be redesigned to reduce artifacts by rearranging placement of the most attenuating materials.

• Toxicological Research
• /
• v.24 no.3
• /
• pp.175-182
• /
• 2008

DNA-dependent protein kinase(DNA-PK) is involved in joining DNA double-strand breaks induced by ionizing radiation or V(D)J recombination and is activated by DNA ends and composed of a DNA binding subunit, Ku, and a catalytic subunit, DNA-PKcs. It has been suggested that DNA-PK might be $2^{nd}$ upstream kinase for protein kinase B(PKB). In this report, we showed that Ser473 phosphorylation in the hydrophobic-motif of PKB is blocked in DNA-PK knockout mouse embryonic fibroblast cells(MEFs) following insulin stimulation, while there is no effect on Ser473 phosphorylation in DNA-PK wild type MEF cells. The observation is further confirmed in human glioblastoma cells expressing a mutant form of DNA-PK(M059J) and a wild-type of DNA-PK(M059K), indicating that DNA-PK is indeed important for PKB activation. Furthermore, the treatment of cells with doxorubicin, DNA-damage inducing agent, leads to PKB phosphorylation on Ser473 in control MEF cells while there is no response in DNA-PK knockout MEF cells. Together, these results proposed that DNA-PK has a potential role in insulin signaling as well as DNA-repair signaling pathway.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.8 no.2
• /
• pp.213-221
• /
• 2005

Purpose: Hemophagocytic syndrome (HPS) is characterized by persistent high fever, hepatosplenomegaly, cytopenias, hypertriglyceridemia, and/or hypofibrinogenemia. Hepatic manifestations including overt hepatic failure and fulminant hepatitis are common in HPS. Liver transplantation (LT) should be considered in a case of fulminant hepatitis by other than HPS, but LT is contraindicated and complete cure is possible by chemotherapy in HPS. Therefore, we conducted this study to define the characteristics of HPS presenting as severe acute hepatitis. Methods: Among the total of 23 patients diagnosed as HPS by bone marrow examination between 1994 and 2005 in Asan Medical Center, 11 cases presented as severe acute hepatitis were enrolled in this study. We analyzed the clinical features, laboratory findings and outcome retrospectively. Results: Seven (64%) of the 11 children with HPS and hepatitis were referred to pediatric gastroenterologist at first. The mean age of onset was 50 months. There was no case with family history of primary HPS. Epstein-Barr virus was positive in 4, and herpes Simplex virus was positive simultaneously in 1 case. As the presenting symptoms and signs, fever was present in 10, hepatosplenomagaly was noted in all and jaundice in 10. Anemia was observed in 10, thrombocytopenia in 10, leukopenia in 8, hypertriglyceridemia in 9, hypofibrinogenemia in 8 and hyperferritinemia in 7 cases, respectively. Nine children received chemotherapy including etopside. The overall mortality rate was 72% (8/11). Conclusion: HPS, which needs chemotherapy, should be considered as a cause of severe acute hepatitis especially when accompanied with prolonged high fever and cytopenias.

• Journal of Radiation Protection and Research
• /
• v.36 no.2
• /
• pp.71-78
• /
• 2011

Yeong-Gwang N.P.P Private Environment Supervisory Organization analyzed over 3,000 samples including 10 marine and 24 land samples from the year 2,000 to 2009. According to the results of the analysis, artificial nuclides that resulted from the effect of Yeong-Gwang Nuclear Power Plant operations were not detected in most samples. However, from the rain and seawater samples, which were taken from inside the plants such as the intake, the discharge and the observatory, $^3H$ was detected although it was below the regulation level. The $^3H$ concentration detected in the rain taken from the observatory, by the yearly average criterion, was 30.5~40.0 $Bq{\cdot}L^{-1}$, which is around 20 times the $^3H$ concentration detected in the surroundings of the power plants, but it is 0.1% of the regulation level of 40,000 $Bq{\cdot}L^{-1}$. Also, $^3H$ concentration detected in the seawater taken from the intake and the discharge, by the yearly average criterion, was 2.75~17.8$Bq{\cdot}L^{-1}$, which means the concentration detected in the discharge is about 140~280% higher than that detected in the intake except the year 2006. Based on these results, it was determined that, although lower than the regulation level, the $^3H$ in gas and liquid form detected in the rain and seawater sampled from the observatory and the discharge was released into the environment from the power plants. Therefore, regular monitoring and analysis is required on the level of $^3H$ in the observatory and the discharge.

• Clinical and Experimental Pediatrics
• /
• v.52 no.5
• /
• pp.588-593
• /
• 2009

Purpose : To investigate whether growth hormone (GH) has a protective effect on neurons in hippocampal slice cultures of neonatal rats exposed to oxygen-glucose deprivation (OGD). Methods : Cultured hippocampal slices of 7-day-old rats were exposed to OGD for 60 min. Then, the slices were immediately treated with three doses of GH (5, 50, or $500{\mu}M$) in media. The relative fluorescent densities of propidium iodide (PI) uptake in the slices and relative lactate dehydrogenase (LDH) activities in the media were determined and compared between each GH- treated group of slices and untreated slices (control) at 12 and 24 h after OGD. Immunofluorescent staining for caspase-3 and TUNEL staining were performed to observe the effect of GH on apoptotic neuronal death. Results : The relative fluorescent densities of PI uptake in CA1 and dentate gyrus (DG) of the hippocampal slices in each GH-treated group were not significantly different from those in the untreated slices at 12 and 24 h after OGD (P>0.05). Treatment with GH could reduce the relative LDH activities in the media of the GH-treated groups only at 12 h after OGD (P<0.05). Expression of caspase-3 and TUNEL positivity in CA1 and DG of the slices treated with 50-iM GH were not different from those of the untreated slices at 12 and 24 h after OGD. Conclusion : Treatment of hippocampal slice cultures with GH after OGD does not show a definitive protective effect on neuronal death but can reduce the LDH efflux of the slices in media at 12 h after OGD.