Korea's developmental program for superconductivity

Superconductivity research in Korea was firstly carried out in the late 70's by a research group in Seoul National University (SNU), who fabricated a small scale superconducting magnetic energy storage system under the financial support from Korea Electric Power Company (KEPCO). But a few researchers were involved in superconductivity research until the oxide high Tc superconductor was discovered by Bednorz and Mueller. After the discovery of YBaCuO superconductor operating above the boiling point of liquid nitrogen (77 K)(exp 2), Korean Ministry of Science and Technology (MOST) sponsored a special fund for the high Tc superconductivity research to universities and national research institutes by recognizing its importance. Scientists engaged in this project organized 'High Temperature Superconductivity Research Association (HITSRA)' for effective conducting of research. Its major functions are to coordinate research activities on high Tc superconductivity and organize the workshop for active exchange of information. During last seven years the major superconductivity research has been carried out through the coordination of HITSRA. The major parts of the Korea's superconductivity research program were related to high temperature superconductor and only a few groups were carrying out research on conventional superconductor technology, and Korea Atomic Energy Research Institute (KAERI) and Korea Electrotechnology Research Institute (KERI) have led this research. In this talk, the current status and future plans of superconductivity research in Korea will be reviewed based on the results presented in interim meeting of HITSRA, April 1-2, 1994. Taejeon, as well as the research activity of KAERI

(1,2-Dicarba-closo-dodeca­boran­yl)trimethyl­methanaminium iodide

The title compound, [1-(CH3)3NCH2-1,2-C2B10H11]+·I− or C6H22B10N+·I−, was obtained by the reaction of (1,2-dicarba-closo-dodeca­boran­yl)dimethyl­methanamine with methyl iodide. The asymmetric unit contains two iodide anions and two (o-carboran­yl)tetra­methyl­ammonium cations. The bond lengths and angles in the carborane cage are within normal ranges, but the N—Cmethyl­ene—Ccage angle is very large [120.2 (2)°] because of repulsion between the carborane and tetra­methyl­ammonium units. In the crystal, ions are linked through C—H⋯I hydrogen bonds

Cultural Practices to Reduce Cd Content in Edible Parts of Staple Crops in Korea

Objectives of this study were to determine the uptake and translocation of Cd in rice plant from soil with applying the water management and soil ameliorators and to investigate the correlations among heavy metal contents in the brown rice, soil pH and chemical species of Cd existing in soil by sequential extracting method with paddy soil contaminated with Cd near abandoned mine. To identify the effect of soil ameliorators on Cd uptake in rice plants, compost and lime were treated. Plants were grown with irrigation water concentrated by 0.01mg kg^ of cadmium in two soil types (sandy loam and clay loam) with treatments of intermittent irrigation and continuous submersion conditions. Compared to intermittent irrigation plots, average Eh value in the continuous submersion plots was low at 136.7mV whereas pH value was high at 0.3. Eh value was decreased in the treatment of soil ameliorator while pH value was increased by 0.2～0.3. Cd content of leaves and brown rice had significantly positive correlation with Eh value in soils while was negatively correlated with soil pH. At the harvest stage, Cd content in the leaves and brown rice was decreased in the continuous submersion plots by 30% relative to the intermittent irrigation plots. In case of soil ameliorator applied plots, Cd content of leaves and brown rice was lower by 35% than that of N, P, K fertilizer plots, respectively. Compared to the soil types, Cd content of leaves and brown rice in sandy loam soil was lower by 64 and 37% than that in clay loam soil, respectively. Order of reduction to Cd uptake was the compost and lime mixture plot>silicate plot>lime plot. However, the effect of Cd uptake reduction by soil ameliorator was decreased in the N, P, K+compost and N, P, K+phosphate plots. Cd uptake reduction by water management and soil ameliorator was more effective in the sandy loam soil than that in the clay loam soil.Special Revie

Seasonal Prevalence of Mosquitoes, Including Vectors of Brugian Filariasis, in Southern Islands of the Republic of Korea

A survey of mosquitoes, including the vector status of Brugia malayi filariasis and their relative larval density, was conducted from 2002 to 2005 at several southern remote islands of Jeollanam-do (province), Gyeongsangnam-do, and Jeju-do, Korea, where filariasis was previously endemic. Overall, a total of 9 species belonging to 7 genera were collected. Ochlerotatus togoi (formerly known as Aedes togoi), Anopheles (Hyrcanus) group, and Culex pipiens were the predominant species captured at all areas. Oc. togoi larvae were most frequently collected at salinity levels <0.5% during June and July, with densities decreasing sharply during the rainy season in August. The most likely explanation for the eradication of filariasis in these areas is suggested to be an aggressive treatment program executed during the 1970s and the 1990s. However, high prevalence of the vector mosquitoes may constitute a potential risk for reemerging of brugian filariasis in these areas

Power Limiter with PIN Diode Embedded in Cavity to Minimize Parasitic Inductance

This letter introduces a power limiter that limits the input power to protect the receiver when a large power enters the radio frequency receiver. When the power limiter receives a large power signal, a positive-intrinsic-negative (PIN) diode is turned on to limit the input power by lowering the impedance. We analyzed the characteristics of the power limiter according to the method of connecting the PIN diode in parallel with the input and output transmission lines of the power limiter. By embedding a PIN diode into the cavity and minimizing the length of the wire, a power limiter was designed and implemented to minimize parasitic inductance. In the S-band, the proposed power limiter’s insertion loss was below 0.5 dB, and the reflection loss characteristics were below 15 dB. Furthermore, it achieved an output P1dB of 21.8 dBm at 3.5 GHz

Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant

We present far-ultraviolet observations of the Antlia supernova remnant obtained with Far-ultraviolet IMaging Spectrograph (FIMS, also called SPEAR). The strongest lines observed are C IV 1548,1551 and C III 977. The C IV emission of this mixed-morphology supernova remnant shows a clumpy distribution, and the line intensity is nearly constant with radius. The C III 977 line, though too weak to be mapped over the whole remnant, is shown to vary radially. The line intensity peaks at about half the radius, and drops at the edge of the remnant. Both the clumpy distribution of C IV and the rise in the C IV to C III ratio towards the edge suggest that central emission is from evaporating cloudlets rather than thermal conduction in a more uniform, dense medium.Comment: 9 pages, 4 figures, will be published in ApJ December 1, 2007, v670n2 issue. see http://astro.snu.ac.kr/~jhshinn/ms.pd

Outcomes of endovascular treatment for aortic pseudoaneurysm in Behcet's disease

ObjectiveTo evaluate the effectiveness of endovascular stent grafting for surgical management of aortic pseudoaneurysm in patients with Behcet's disease (BD).MethodsWe present a single-institution retrospective cohort of patients with aortic pseudoaneurysm and BD treated with aortic stent grafting. Computed tomography imaging was obtained preoperatively in all patients and once within 2 weeks postoperatively, and then annually. Clinical follow-up and erythrocyte sedimentation rate were used to follow BD activity. Immunosuppressant therapy was instituted prior to endovascular treatment unless a contraindication existed.ResultsFrom 1998 to 2012, 10 patients (eight male, two female; median age, 39) with BD and aortic pseudoaneurysm were treated with endovascular stent grafting at this institution. Ninety percent of these patients received immunosuppressive therapy before and after surgical treatment. The median follow-up period was 57 months (interquartile range, 43-72). The locations of the 12 pseudoaneurysms treated in this cohort were infrarenal abdominal aorta (seven), descending thoracic aorta (four), and aortic arch (one). Median pseudoaneurysm size was 4.5 cm (interquartile range, 3.4-5.9). At long-term follow-up, complete resolution of the aortic pseudoaneurysm was noted in all patients. No endoleaks occurred. Newly developed pseudoaneurysm at the distal margin of the stent graft was noted in one patient 17 months after the stent graft procedure. One patient required a subsequent stent graft placement for an expanding pseudoaneurysm of the subclavian artery. No patient deaths occurred during the follow-up period.ConclusionsEndovascular treatment of aortic pseudoaneurysm with stent-grafting in patients with BD is safe and effective with long-term durability

Low-resistance Ti/Al ohmic contact on undoped ZnO

We report a low-resistance ohmic contact on undoped ZnO using a promising contact scheme of Ti/Al. Specific-contact resistivity, as low as 9.0 x 10(-7) Omegacm(2), was obtained from the Ti(300 Angstrom)/Al(3,000 Angstrom) contact annealed at 300degreesC. It was found that TiO was produced, and the atomic ratio of Zn/O was dramatically increased after annealing at 300degreesC. This provides the evidence that a number of oxygen vacancies, acting as donors for electrons, were produced below the contact. This leads to the increase of electron concentration via the reduction of contact resistivity