• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11A
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• pp.882-890
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• 2009

In this paper, we describe a compensation method that can be used for the situation where Loran receivers lose their phase lock to the received Loran signals when Loran signals are employed for the synchronization of national infrastructures such as telecommunication networks, electric power distribution and so on. In losing the phase lock to the received signals in a Loran receiver, the inner oscillator of the receiver starts free-running and the performance of the timing synchronization signals which are locked to the oscillator's phase is very severly degraded, so the timing accuracy under 1 us for a Primary Reference Clock (PRC) required in the International Telecommunications Union (ITU) G.811 standard can not be satisfied in the situation. Therefore, in this paper, we propose a method which can compensate the phase jump by using a compensation algorithm when a Loran receiver loses its phase lock and the performance evaluation of the proposed algorithm is achieved by the Maximum Time Interval Error (MTIE) of the measured data. From the performance evaluation results, it is observed that the requirement under 1 us for a PRC can be easily achieved by using the proposed algorithm showing about 0.6 us with under 30 minutes mean interval of smoothing with 1 hour period when the loss of phase lock occurs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.496-502
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• 2007

In this paper, a slotted waveguide feeder for the electric field uniformity in multi-mode cavity is designed and fabricated. In case of the conventional feeder, a mode stirrer or a turntable is used for improving electric field uniformity in the multi-mode cavity. The proposed feeder has four slots, which have uniform radiation characteristic, on broad wall and shorted terminations at both ends. The electric field uniformity is simulated by CST's MWS(Microwave Studio) for the conventional and proposed feeders, respectively. The fabricated feeder shows the return loss of less than -20 dB at 2.45 GHz. To verify the validity of our proposal, the temperature distribution of the water samples in the multi- mode cavity is observed after a few minutes' heating. The proposed feeder is confirmed to have much better field uniformity in the multi-mode cavity than the conventional feeder.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.285-291
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• 2015

Exposure to cold sea water can be life-threatening to the drowned individual. Although appropriate life jacket can be usually be provided for the buoyance at the drowning accident, heat loss can make the drowned individual experience the hypothermia. Inflatable life jackets filled with inflatable air pocket can increase the thermal protection as well as the buoyancy force. Because it is important to know how the human body behaves unde the different life jacket, present study compares the thermal insulation capacity of solid type life jacket with that of inflatable life jacket. In order to represent the insulation capacity of life jacket, thermal resistance is estimated based on the assumption of steady-state. Also, a transient three-dimensional thermal distribution of the thigh is analyzed by using finite element method implementing the Pennes bioheat equation. The finite element model is a segmental, multi-layered representation of the body section which considers the heat conduction within tissue, bone, fat and local blood flow rate.

• Journal of Navigation and Port Research
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• v.41 no.6
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• pp.451-466
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• 2017

Deep-sea fishing vessel No. 501 Oryong was fully flooded through its openings and sunk to the bottom of the sea due to the very rough sea weather on the way of evasion after a fishing operation in the Bearing Sea. As a result, many crew members died and/or were missing. In this study, a full-scale ship flooding sinking simulation was conducted, and the sinking process was analyzed for the precise and scientific investigation of the sinking accident using highly advanced Modeling & Simulation (M&S) system of Fluid-Structure Interaction (FSI) analysis technique. To objectively secure the weather and sea states during the sinking accident in the Bering Sea, time-based wind and wave simulation at the region of the sinking accident was carried out and analyzed, and the weather and sea states were realized by simulating the irregular strong wave and wind spectrums. Simulation scenarios were developed and full-scale ship and fluid (air & seawater) modeling was performed for the flooding sinking simulation, by investigating the hull form, structural arrangement & weight distribution, and exterior inflow openings and interior flooding paths through its drawings, and by estimating the main tank capacities and their loading status. It was confirmed that the flooding and sinking accident was slightly different from a general capsize and sinking accident according to the simple loss of stability.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.526-536
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• 2009

The aim of this vitro-study is to evaluate the effects of fluoride on remineralization of artificial dentine caries. 10 sound permanent premolars, which were extracted for orthodontic reason within 1 week. were used for this study. Artificial dentine caries was created by using a partially saturated buffer solution for 2 days with grounded thin specimens and fractured whole-body specimens. Remineralization solutions with three different fluoride concentration (1 ppm. 2 ppm and 4 ppm) were used on demineralized-specimens for 7 days. Polarizing microscope and scanning electron microscope were used for the evaluation of the mineral distribution profile and morphology of crystallites of hydroxyapatite. The results were as follows: 1. When treated with the fluoride solutions, the demineralized dentine specimens showed remineralization of the upper part and demineralization of the lower part of the lesion body simultaneously. 2. As the concentration of fluoride increased, the mineral precipitation in the caries dentine increased. The mineral precipitation mainly occurred in the surface layer in 1 and 2 ppm- specimens and in the whole lesion body in 4 ppm -specimens. 3. When treated with the fluoride solution, the hydroxyapatite crystals grew. This crystal growth was even observed in the lower part of the lesion body which had shown the loss of mineral.

• Magazine of the Korean Society of Agricultural Engineers
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• v.8 no.1
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• pp.1088-1096
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• 1966

The following is a method of synthetic unitgraph derivation based on the routing of a time area diagram through channel storage, studied by Clark-Jonstone and Laurenson. Unithy drograph (or unitgraph) is the hydrograph that would result from unit rainfall\ulcorner excess occuring uniformly with respect to both time and area over a catchment in unit time. By thus standarzing rainfall characteristics and ignoring loss, the unitgraph represents only the effects of catchment characteristics on the time distribution of runoff from a catchment The situation abten arises where it is desirable to derive a unitgraph for the design of dams, large bridge, and flood mitigation works such as levees, floodways and other flood control structures, and are also used in flood forecasting, and the necessary hydrologie records are not available. In such cases, if time and funds permit, it may be desirable to install the necessary raingauges, pruviometers, and stream gaging stations, and collect the necessary data over a period of years. On the otherhand, this procedure may be found either uneconomic or impossible on the grounds of time required, and it then becomes necessary to synthesise a unitgraph from a knowledge of the physical charcteristics of the catchment. In the preparing the approach to the solution of the problem we must select a number of catchment characteristic(shape, stream pattern, surface slope, and stream slope, etc.), a number of parameters that will define the magnitude and shape of the unit graph (e.g. peak discharge, time to peak, and base length, etc.), evaluate the catch-ment characteristics and unitgraph parameters selected, for a number of catchments having adequate rainfall and stream data and obtain Correlations between the two classes of data, and assume the relationships derived in just above question apply to other, ungaged, Catchments in the same region and, knowing the physical characteritics of these catchments, substitute for them in the relation\ulcorner ships to determine the corresponding unitgraph parameters. This method described in this note, based on the routing of a time area diagram through channel storage, appears to provide a logical line of research and they allow a readier correlation of unitgraph parameters with catchment characteristics. The main disadvantage of this method appears to be the error in routing all elements of rainfall excess through the same amount of storage. evertheless, it should be noted that the synthetic unitgraph method is more accurate than the rational method since it takes account of the shape and tophography of the catchment, channel storage, and temporal variation of rainfall excess, all of which are neglected in rational method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6221-6226
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• 2015

In this paper, waveguide analysis was interpreted as an optical waveguide using the feedback perturbation method simple and easy to apply compared to the analysis method, while the other almost identical to the numerical calculation method. In addition, efficient coupling with an optical transmission line of optical fiber and the waveguide form the thin film of different functional elements is required in order to achieve the full optical communication system. However, problems arise, such as the light field (field) and the decrease of the access efficiency due to inconsistency in the distribution characteristics of the connection surface by the difference in size of the cross section thereof when connecting the optical fiber and the waveguide directly to the combination of a thin film. Therefore propose a new type of connector structure to increase the efficiency of the connection when connecting the optical fiber waveguide and the thin film was analyzed by applying a coupled mode theory, the binding efficiency of the modified contactor. And by diffusing Ti on the $LiNbO_3$ substrate and a wide range of applications in the manufacture of integrated optical material made of a current low-loss Ti: $LiNbO_3$ optical waveguide and making the Y-branch waveguide, and the properties were confirmed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2004-2010
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• 2009

The characteristic of the backbond for distribution service in WMNs(Wireless Mesh Networks) is that WMNs has multiple links connected to mesh points and dynamic routing protocol such as AODV to establish routing paths. When the terminal is communicating with the service through new AP, mobile nodes can resume communication by setting only the link between new AP and mobile node in the case of existing WLANs, but WMNs needs path establishment process in multihop networks. Our goal in this paper is to support the seamless communication service by eliminating path establishment delay in WMNs. We present the method that eliminates the handover latency by predicting the location of handover using GPS information and making the paths to their destination in advance. We implement mesh nodes using embedded board that contains proposed handover method and evaluate performance of handover latency. Our experiment shows that handover delay time is decreased from 2.47 to 0.05 seconds and data loss rate is decreased from 20~35% in the existing method to 0~10% level.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.30 no.4
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• pp.1-24
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• 2017

Objectives : The purpose of this study is to research on the characteristics of outpatients and distributions of diseases in ophthalmology, otolaryngology of Korean medicine in 2012-2016 and compare the result with previous studies. Methods : This study is based on the analysis of medical records of total 2,319 outpatients in ophthalmology, otolaryngology of Korean medicine at Kyung Hee Korean medicine hospital from January 1, 2012 to December 31, 2016. We searched on the demographic characteristics of outpatients and the distributions of diseases in order of frequency by age and sex. Then, we compared these results to previous results of papers at same hospital in 2000 and 2007. Results : The common diseases in 2012-2016 were dry eye syndrome in ophthalmology(32.14%), tinnitus and hearing loss in otology(72.69%), rhinitis in rhinology(82.20%) and laryngopharyngitis in laryngology(67.77%). The most increasing diseases in the distribution between 2004-2006 and 2012-2016 were retinopathy in ophthalmology(+366.77%), etc including the eustachian tube disorder in otology(+151.55%), olfactory disorder in rhinology(+167.50%) and laryngopharyngitis in laryngology(+126.20%). Conclusions : If we accumulate these kinds of epidemiologic studies on ophthalmology, otolaryngology of Korean medicine, it will be great help to make Korean medical preparations for the increasing diseases on these fields.

• Journal of Sericultural and Entomological Science
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• v.35 no.1
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• pp.60-68
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• 1993

It has been known that the silk degumming treated by hot alkali solution is easy to handle but is liable to yield poor-quality silk due to the degree of degumming loss, incomplete-degumming or over-degumming. Therefore, many studies have been carried out on the silk degumming by enzyme in order to improve the quality of silk. However, no attention has been paid to the physicochemical analysis of enzymatic degummed silk. In this paper, two different degumming methods, soap and enzymatic, are compared in aqueous solution state of silk fibroin. The results can be summarized as follows: There was no significant difference between two solutions on the bases of polarizing microscopy, TEM observation and SDS-PAGE. Spherulite of silk fibroin was not observed in polarizing microscopy, however the leaf-shape fibril structure was developed upon solidification. The size of spherulites of silk fibroin in TEM observation were 30~120nm with a wide range of size distribution. The intrinsic viscosity of enzymatic degummed fibroin solution was lower than that of soap degummed solution. This can be explained that the silk fibroin was more degraded by enzymatic degumming method compared with the soap degumming method. SDS-polyacrylamide gel electrophoresis showed that the fibroin molecule was composed of large component of molecule weight above 50 kd and small component of molecule weight about 20 kd. There was no difference in crystallinity between two degumming methods on the bases of results of DSC thermograms and IR spectra.