• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.11-19
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• 2013

In this paper, we designed and implemented the planar monopole antenna using the coupling effect for the multi-band characteristic. A parasitic element for the multi-band characteristic based on a rectangular patch with single resonance is inserted. Spiral shaped parasitic element is used for minimizing the antenna size and obtaining the multi-resonance characteristic. The frequency characteristics are modified and optimized by varying specific parameters. By inserting an L-shaped resonator at both sides of the feed line which connected through the via hole to the ground plane, unnecessary frequency bands are eliminated. Proposed antenna dimension is $40{\times}60{\times}1mm^3$. It is fabricated on the FR-4 substrate(${\varepsilon}_r$=4.4) using a microstrip line of $50{\Omega}$ for impedance matching. By measurement results, the characteristic of the return loss under -10 dB are 1.714~2.496 GHz, 2.977~4.301 GHz, and 4.721~6.315 GHz, and the radiation patterns have omni-directional shapes.

• Journal of Chest Surgery
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• v.31 no.3
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• pp.221-225
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• 1998

From February 1996 to May 1997, 18 patients underwent mitral valve repair for mitral regurgitation. There were 9 male and 9 female patients aged from 19 to 68 years(mean, 53). Thirteen patients were in New York Heart Association(NYHA) class III and IV. The cause of mitral regurgitation was degenerative in 12 patients, rheumatic in 5 patients and infective in 1 patient. Fifteen patients were in Carpentier's functional classification II, 2 patients in Carpentier's class III and 1 patient in Carpentier's class I. Surgical procedures included prosthetic ring annuloplasty(16 cases), rectangular resection of posterior leaflet(15 cases), chordal shortening(5 cases), triangular resection of anterior leaflet(2 cases), commissurotomy(2 cases), partial transposition of posterior leaflet(1 case). These procedures were combined in most patients. There was no operative death. These patients have been followed from 1 to 15 months, mean of 6.7 months. There was one late death resulted from low cardiac output following mitral valve replacement. The function of the repaired valve in other 17 patients has remained satisfactory during the observed interval. We consider that mitral valve repair is highly satisfactory in patients with mitral regurgitation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.275-285
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• 2021

COVID-19 is threatening the safety of ships and seafarers by delaying seafarer rotation. Shipping companies and governments have a blindspot in case of the onboard environment of seafarers. An effective, alternative plan should be devised to eliminate the possibility of human accidents in an emergency that threatens the safety of seafarers. According to the survey of former and current seafarers, the most important factor in boarding life was safety, and the most necessary thing during emergencies was to secure smooth seafarer rotation rather than improve wages and welfare. By analyzing the major routes of national shipping companies by continent, ports with a large number of calls and a high Air Connectivity Index were selected as the base port. In addition, the route was designed for effective, domestic seafarer rotation during international shipping. Other countries must be consulted to establish a travel route linking ships, ports, and airports for the safe return of sailors to their home countries during an emergency. In addition, it is necessary to work together for the seafarers who are in trouble of seafarer rotation through cooperation with the International Maritime Organization(IMO). Starting with this, the government should have a monitoring system for the return and non-return routes as well as the number of seafarers on board. If such a system is established, it will be able to determine the response direction of our country's policy in case of an emergency. Along with the shipping company's ef orts to improve the treatment of seafarers, national and social attention will be needed to review domestic laws and improve awareness about seafarers.