• The Korean Journal of Applied Statistics
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• v.8 no.1
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• pp.89-104
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• 1995

This paper is concerned with the method of estimating lifetime distributin from field data for products with multiple modes of failure. When product failures occur within warranty period, a manufacturer can obtain failure-record data; failure times, causes of failure, and covariates. Since these data are seriously incomplete for satisfactory inference, that is, only failures occured during warrantly period may be recorded, it is usually necessary to incoporate the failure-record data by taking a supplementary sample of items obtained following up a portion of products that survive warranty time. The log linear function is considered as a model for describing the relation between failure time of a product and covariates. General methods for obtaining pseudo maximum likelihood estimators(PMLEs) for the parameters are outlined and their asymptotic properties are studied, and specific formulas for exponential or Weibull distribution are obtained. Effects of follow-up percentage on the PMLEs are investigated. Extensions to calendar time warranty or calendar and obtaining time warranty are also considered.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.42-49
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• 2017

Delay- and Disruption-Tolerant Network (DTN) has been considered as a key technology to overcome main challenges in interplanetary communications such as an intermittent connectivity and high bit error rates. The lack of end-to-end connectivity between source and destination results in long and variable delays and data loss, hence the Internet Protocols cannot operate properly in such environments because it requires an end-to-end connectivity. The DTN, which utilizes 'store-and-forward' message passing scheme between nodes, can overcome the lack of end-to-end connectivity in Interplanetary Network (IPN). In this paper, DTN is applied to 3-hop relay IPN, where messages are transmitted from Earth ground station to Lunar lander through Earth satellite and Lunar orbiter. ONE simulator is used to reflect the real environment of IPN and an efficient resource management method are analyzed to guarantee the message delivery by optimizing a message TTL (Time to Live), buffer size and message fragmentation.

• Proceedings of KOSOMES biannual meeting
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• 2005.11a
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• pp.21-26
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• 2005

The work of VLCC SPM mainly is accomplished on the open sea On the open sea as a result of meteorological condition and the ocean wave influence, When the weather condition is get bed, peremptorily moving to the safety place, because of the gale and the billow, almost happened frequently, the pilot is unable to go on board and the tug is also unable to be used Now bemuse of the bad weather the VLCC SPM moving to the other safety place frequently happened in the ulsan port. the construction of new harbor, it constructed many break water around SPM. So that it is necessary to propose the new standard about how to maneuvering area actually. Now our country is at the blank stage about the establishment of SPM research Most of the situations are refer to overseas standard But these standards lack of consistency and clarity. So when moving to the other safety place from SPM, we must carry through the researching and study on the ships using by sailing data of AIS. we must put forward a new standard about maneuvering area of ship in moving at SPM.

• Proceedings of KOSOMES biannual meeting
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• 2004.05b
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• pp.107-112
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• 2004

In order to improve the safety r! ship berthing and the efficiency r! berth operation in the harbour, the berthing energy acting on a ship in berthing maneuver need to be estimated properly. The berthing energy is used as one q the criteria to determine the maximum permissible load of fender as well as important factors to establish the berthing speed and the required power r! tug-beat for pilot and ship operator. In this study, some problems r! present the method of berthing energy are discussed on the basis of the hydrodynamic aspects. Then, series calculations of berthing energy are carried out considering the effect of water depth on added mass and the ship shape for container series from 1,600TEU to 12,000TEU.

• Journal of Korean Physical Therapy Science
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• v.7 no.1
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• pp.333-352
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• 2000

The objective of this study was to identify the effects of the cognitive performance of stroke patients on their motor function recovery after comprehensive rehabilitation management. The subjects of this study were 41 stroke in-patients of the Rehabilitation Hospital, College of Medicine, Yonsei University, hospitalized during the period from September 1, 1997 to May 5, 1998. The cognitive performance was measured using a Mini-Mental State Examination(MMSE) and the motor function recovery using Motor Assessment Scale(MAS). The data were analyzed by the paired t-test, independent t-test, a one way ANOVA, and Pearson's correlation coefficiency. The findings were as follows: 1. There was a significant difference found in the motor function recovery level after the comprehensive rehabilitation management. 2. There was no significant difference found in relation to sex, age, cause of stroke, laterality of paralysis and the level of spasticity. However, there was a big difference between pre- and post-treatment regarding the treatment period. 3. In line with the cognitive performance level, there was a significant difference found in the motor function recovery level after the comprehensive rehabilitation management. 4. The correlation between the elements of the cognitive performance and the motor recovery was found to be high in orientation, attention, calculation, and language. Those elements were expected to give larger effects on motor recovery after the comprehensive rehabilitation management. Based on this study, the cognitive performance level was found to play an important role in bringing effects on motor recovery after the comprehensive rehabilitation management of stroke patients. And the evaluation on the motor recovery based on quality would be also expected to be examined, as well as the cognitive performance level test accompanied by Intelligence Quality(IQ) test.

• Journal of Korean Physical Therapy Science
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• v.7 no.1
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• pp.367-375
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• 2000

The purpose of this study is to announce the present condition, walking training, and adaptable training of a limb amputated patient. The study is a successful report of the limb amputated patient through the medical treatment of the physical therapy. A cause of the limb amputated patient, a truck driver, was that the patient was hit by a train when the driver alight from the truck. Then, the driver was surgical operated on left AK (Above Knee) amputation and left AE (Above Elbow) amputation by orthopedics at the Young Dong Severance Hospital on Dec.7, 1996. Two weeks after the operation (Dec., 22, 1996), the patient was trained at the Yonsei Medical Center Physical Therapy Hospital for the walking and temper adjust training. It was possible to do a flat surface walking and a slope surface walking without helping due to the patients optimistic personal character and motivation. However, the patient struggled to a dull surface walking and his weak endurance. the patient has several problems when the patient wears artificial legs and hands, fears on fall down, and mentally worries on noise when he walks. It is necessary to approach for this problems by many fields of the helpers, such as Rehabilitation medical doctor, physical therapist, occupational therpist, artificial limbs makers, psychologists, and etc. Therefore, in order for recovering from the amputated parts function after the surgical operation, more approved reports have to be for the amputated patients due to increasing traffic accidents, industrial disaster, cancer, diabetes, obstacles of the peripheral nervous system, and etc.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.555-562
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• 2007

The environs of Korea in winter season are influenced by the distribution of atmospheric pressure, namely, the typical east-low and west-high pattern that is formed from both the Siberian continental high pressure and the Aleutian oceanic low pressure. In this reason, the violent West or North-West monsoon, the billows with the strong wind, and the tremendous heavy snowfall are encountered very frequently in the West Sea. In this study, the trajectories of the extratropical cyclone are analysed to choose the safe refuge areas of National Fishery Supervision Vessel using the surface analysis weather chart for 11 years from 1994 to 2004. The safe refuge areas according to the trajectories of the extratropical cyclone in the West Sea are decided using data that contain the topographical properties of island, the depth of water, the state of low quality, the influence of tidal current, and the distribution of fishing-net.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.3
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• pp.199-205
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• 2013

In this study, the methodology for the fatigue life prediction using finite element method(FEM) in wire, bundle and assembly level of the wire harness system and the development of the fatigue life test machine for the numerical analysis are investigated. To obtain stress-life(S-N) histories of the componential wires of the system, five kinds of wires are prepared and applied to the repeated bending motion using developed fatigue life test equipment. Equivalent model of the wire from the rule of mixtures theory is used for the material modeling of sheath and wire core combination. Contact conditions among the wires, taping conditions are established through the bundle level test and numerical bundle analysis. Wire and bundle level results are adopted for the assembly level analysis. For the assembly level analysis, real wire harness system including bundle and grommet is numerically modeled and applied contact condition between wires with real opening motion. The fatigue life more than 700,000 cycles of the assembly is obtained from the FEM, and it is confirmed that the result has good agreement with the experimental result.

• Journal of dental hygiene science
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• v.3 no.1
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• pp.11-14
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• 2003

A methylotrophic Actinomycetes strain, which produce the anti-oral cancer activity compound, was isolated from soil and estimated as Amylocolatosis sp. based on taxonomic studies. A methanol didn't have influence on the production of the anticancer compounds. These compound were isolated by ethylacetate extract, silica gel column chromatography, sephadex LH-20 column and reverse phase HPLC. The compounds were very stable under heat ($121^{\circ}C$), acid(pH 2.0) and alkali(pH 11.0) treatment. The cytotoxic effect of isolated anticancer compounds on various cancer cell lines such as A549, SNU-1, KB, L1210, and Sarcoma 180 was investigated by MTT assay method. And these produced compounds also showed the broad antimicrobial spectrum to test strains such as bacteria and yeast.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.455-462
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• 2015

In this paper, we suggested multiband antenna that can be equipped on a inflatable life-jacket, operating VHF-DSC band(156 MHz), COSPAS-SARSAT band(406 MHz) and GPS band(1,575 MHz) for search and rescue survivors quickly. The GPS band antenna was implemented with a square ring-slot planar antenna, and the COSPAS-SARSAT and VHF-DSC band antenna were implemented meander type dipole antennas. In order to place the antenna on a life-jacket, we installed it on 0.2 mm thickness FR-4 substrate to obtain a flexibility. It appeared that the antenna has -14.6 dB, -30.9 dB, and -18 dB return loss in COSPAS-SARSAT, GPS, and VHF-DSC band, respectively. In addition, its gain has 0.83 dBi, 2.1 dBi in COSPAS-SARSAT and GPS band, respectively.