• Journal of Communications and Networks
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• v.10 no.1
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• pp.1-4
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• 2008

This paper reports the design of a multiwavelength fiber laser source that utilizes a linear cavity of hybrid Brillouin/Erbium fiber laser (BEFL). The output power, threshold power and free running cavity modes were investigated against the pump powers. The structure exhibited low threshold operation of 4 mW at 2.3 mW injected Brillouin pump power. The optimization of Brillouin pump wavelength, power and Erbium gain led to a maximum possible number of channels generated. Simultaneous and stable operation of 21 channels with 10.88 GHz channels spacing were obtained from this architecture at 1 mW injected Brillouin pump power and 90 m W Erbium doped fiber pump power in the 1555 nm region.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.94-97
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• 2002

A new small signal stability analysis method for eigenvalue analysis is presented. The method is based on the computation of the transition matrix over a specified time interval that corresponds to one cycle operation of the system The method is applicable to any system with or without nonlinear elements. An applicable example of RCF method is presented and the eigenvalues are compared with those of the conventional state space method to show the exactness of the computed eigenvalues of the new method. Also, the variations of oscillation modes which were caused by the switching operation can be analyzed exactly using RCF method.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.352-354
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• 1999

A Switching control circuit based on a micro-controller is developed for blinking operation of fluorescent lamps, which would be suitable for use in the advertising panel. Ten modes of blinking patterns are implanted within the EEPROM. The developed circuit can handle up to 128 fluorescent lamps of 20-40W range, and the lamp life is expected to so beyond 3000 hours.

• International Journal of Fluid Machinery and Systems
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• v.10 no.3
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• pp.264-273
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• 2017

In order to be able to predict the maximum Annual Energy Production (AEP) for tidal power plants, an AEP optimization tool based on Evolutionary Algorithms was developed by ANDRITZ HYDRO. This tool can simulate all operating modes of the units (bi-directional turbine, pump and sluicing mode) and provide the optimal plant operation that maximizes the AEP to the control system. For the Swansea Bay Tidal Power Plant, the AEP optimization evaluated all different hydraulic and operating concepts and defined the optimal concept that led to a significant AEP increase. A comparison between the optimal plant operation provided by the AEP optimization and the full load operating strategy is presented in the paper, highlighting the advantage of the method in providing the maximum AEP.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.3
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• pp.63-73
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• 1993

In this paper, fuzzy control algorithm for the speed ratio control of the electro-hydraulic rig type continuously variable transmission(CVT) was proposed and the CVT performance tests were carried out for the optimal operation of the engine simulator. The experimental results for the constant throttle and the acceleration modes showed that the engine can be run on the optimum operating line, representing the power and economy mode, by the fuzzy control of the CVT speed ratio. Comparing the PID control with the fuzzy control, it was found that the fuzzy control showed better performance with the faster rising time and smaller steady state error. The result of this study can be used as basic design materials for developing the transmission control unit of the CVT.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.233-240
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• 2000

Five scientific instruments are planned on KAISTSAT-4 that is scheduled to be launched in 2002. A far ultra-violet imaging spectrograph and a set of space plasma instruments are currently being designed. The imaging spectrograph will make observations of astronomical objects and Earth's upper atmosphere. The plasma instrumentation is capable of fast measuring the thermal magnetosphere plasmas, cold ionospheric plasmas and the Earth's magnetic fields. Major system drivers and constraints on the payloads as well as the spacecraft are identified. A preliminary analysis of the K-4 mission has been undertaken with the system requirements that are derived from the system drivers. Detailed investigation shows that Sun-synchronous orbits with approximate altitudes of 800km are optimal to satisfy the identified requirements. Comparisons with other orbits of different inclinations are also shown. Four operation modes and a daily schedule of spacecraft maneuver are found from the Sun-synchronous orbital model. It is shown that the scientific objectives of K-4 can be achieved with moderate levels of design and operation risks.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.179-183
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• 1999

Rubbing occurs when a rotating element comes in contact with a stationary element. In the steam turbines, the rotating element is the rotor while the stationary elements are usually the oil deflectors and packing seals. Rubbing phenomenon may be often obseued on a new or rebuilt machine rather than on a machine that has been operating for several months or years. Rubbing in the turbine has been classified into two modes by the operating conditions: 1) start up or shut down, 2) steady state. At start up or shut down operation, rubbing produces synchronous whirl vibration, which are caused by thermal bow of the shaft due to localized heating on the shaft surface. While subsynchronous whirl vibration is caused by partial rubbing during the steady state operation. In this paper, the two case studies of troubleshooting for excessive vibration caused by rubbing in the actual steam turbines are investigated.

• Journal of Chest Surgery
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• v.26 no.12
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• pp.944-949
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• 1993

Clinical analysis were performed on 247 cases of thoracic trauma, those were admitted & treated at the department of thoracic & cardiovascular surgery,Hanyang University Hospital during the period from Jan,1989 to June,1992. Age distribution of those was from 2 to 80 years old & mean age was 38 years old. The ratio of male to female patient was 186:61 [3:1].This ratio revealed high incidence in male patient. The most common cause of trauma was traffic accident in this series.The modes of injury were as follows: traffic accident 124 cases[50.2%],fall down 52 cases[21.05%], stab wound 47 cases[19.03%] and gun-shut wound 1 case.Ellapse time from accident to admission were 141 cases [57.09%] under 6 hr.Rib fracture were observed in 159 cases[64.37%], hemo or pneumothorax were observed 134 cases[54.25%] of total cases and location distributed Right:Left:Both[74:112:37], in left predominant. Conservative,non-operative treatment were performed in 128 cases and operation[open thoracotomy] 32 cases.Mortality was 1.6%[4 cases] & most common cause of death were due to irreversible shock with brain edema. Conclusively, more evaluation & co-operation of other department were expected treatment & better prognosis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.232-237
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• 2006

Operation deflection shapes(ODS) is defined as a motion of structure at particular frequency. The ODS is eligible to show any types of structural motions while the modes supply solutions only to linear and stationary motion. The principal vibration source of an auto teller machine(ATM) case was occurred due to resonance which was found by modal analysis. To reduce the vibration of ATM case, the motion of the case was visualized using ODS analysis, which can suggest how to modify the structure. As a result the vibration of the ATM case was greatly reduced with a stiffening bar between the opposite plates.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.151-153
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• 2016

80/128-비트 마스터키 길이와 ECB, CBC, OFB, CTR의 4가지 운영모드를 지원하는 PRESENT 경량 블록암호 프로세서를 설계하고, Virtex5 FPGA에 구현하여 정상 동작함을 확인하였다. PRESENT 크립토 프로세서를 $0.18{\mu}m$ 공정의 CMOS 셀 라이브러리로 합성한 결과 8,237 GE로 구현되었으며, 최대 434 MHz 클록으로 동작하여 868 Mbps의 성능을 갖는 것으로 예측되었다.