• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.40-42
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• 2013

고압인버터가 적용된 설비의 연속운전을 보장하기 위해 사용하는 절체 기능은 고압모터가 정지한 후 상용전원으로 모터를 기동하는 방법으로 기동 시 과전류와 고압모터 정지 시간 등이 문제점으로 나타난다. 이럴 경우, 고압인버터 출력전압을 상용전원과 동기화 한 뒤 절체하는 동기절체 기능을 사용하면 고압모터가 회전 중일 때에 절체할 수 있으므로, 절체 시 과전류를 줄일 수 있으며, 설비의 연속운전을 보장할 수 있다.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.4
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• pp.289-298
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• 2011

This paper provides procedures to effectively determine arrangement of hydraulic type top-bracings, which are popular for the main engine of the mid and large sized commercial vessels. Analyzing the operation mechanism of hydraulic top-bracing, ideal unified nonlinear stiffness curve is presented for linear frequency response analysis and nonlinear transient response analysis. Nonlinear stiffnesses of the curve are determined based on the regression analysis of test results. It is noted from linear frequency response analysis, initial setting pressure is most important among the setting values of the other stiffness intervals. From transient response analyses for two top-bracing arrangement scenarios, it is recognized that, as far as initial setting pressure is well controlled for the concerning vessels, only two top-bracings are enough to suppress H-mode excitation forces from main engine.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.102-103
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• 2000

화학레이저는 화학연료의 반응에서 생성되는 막대한 화학에너지를 이용하여 레이저를 발생시키며, 반응하는 화학연료의 양에 따라 수천 kW의 고출력을 낼 수 있는 가장 강력한 레이저이다. 화학레이저인 Chemical Oxygen-Iodine Laser(COIL)는 염소기체(Cl$_2$)를 염기성 과산화수소수 용액과 반응시켜 고에너지의 여기산소(O$_2$($^1$$\Delta$))를 생성시키고 여기산소가 다시 요오드 원자와 반응하면서 1.3 $mu extrm{m}$ 파장의 레이저를 발생시킨다.(1)-(2) 이와같은 COIL 레이저는 발진효율이 높고 포화 강도가 높아 수십 kW 급의 고출력이 용이하게 이루어 질 수 있으며 광섬유 전송시 광손실이 가장 적어 레이저 빔의 원격 전송에 의한 재료가공에 적합한 레이저이다. 가공용레이저로 많이 사용하는 $CO_2$ 레이저에 비해 발진 파장이 짧으므로 재료의 광흡수율이 높아 일반 산업분야의 용접/절단에서 기존의 $CO_2$ 레이저를 대체할 것으로 기대되는 상용성이 큰 레이저이다.(3)-(4) 또한 COIL은 우수한 집속 특성을 유지하면서도 고출력의 개발이 가능하다. 이미 외국에서는 비록 단시간 동안 동작하지만 수백 kW급이 실현되었으며 수천 kW 급 고출력 항공기탑재형 COIL 이 수백 km의 거리에서 미사일을 요격하기위해 지금 개발중에 있다.(5) 일반 산업용 광섬유에 의해 쉽게 전송되는 파장인 1.315 $\mu\textrm{m}$ 인 수십 kW 급 COIL 은 조선 등의 중공업산업용 및 원자력 제염/해체분야에서 다용도 기술로서 광범위하게 사용될 것이다. COIL은 다양한 재료와 다양한 두께의 구조물 절단, 표면처리 그리고 용접에도 이용될 수 있다. COIL의 산업화는 빠르게 발전하고 있으며 산업용으로써 장시간 연속사용이 가능한 20-30 kW급 시설이 곧 개발될 것으로 기대된다. 따라서 개발될 고출력 화학레이저가 앞으로 원자력시설의 해체시 작업자의 안전성 향상에 크게 기여할 수 있게 되었다.(6) 여기서는 화학레이저인 COIL 장치와 기본적인 원리, 그리고 염소유량에 따른 출력특성등을 살펴보기로 하겠다. (중략)

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.1
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• pp.55-61
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• 2003

The Data Encryption Standard(DES) has been a worldwide standard for over 20 years. DES is one of the block encryption techniques which ciphers 64-bit input data blocks using a 56-bit private key. The DES algorithm transforms 64-bit input in a series of steps into a 64-bit output. Thus, it is impossible to deduce the plaintext from the ciphertext which encrypted by this algorithm without the key. This paper presents an implementation of RFID roader system using the DES algorithm. An implemented system enhances the credibility of the encryption algorithm by using the Cipher Block Chining(CBC). Experimental results also show that the implemented system has better performance over the conventional commercial product.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.10-16
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• 2005

This paper suggested the sulfur lamp power supply using Fuzzy Gain Scheduling(FGS), which was designed and confirmed the performance through manufacturing. it was based on Series Resonant Half Bridge Inverter(SRHBI), so that was applied Pulse Frequency Modulation(PFM), Zero Voltage Switching(ZVS), soft switching and soft start for input power variation and output power compensation. In order to get the lengthened life time of magnetron and stabilized output or power, power ratter and efficiency were improved by fuzzy gain algorism. It also made it possible to get not the existing foxed output power but continuous variable output power$(900\~1250[W])$. The manufactured power supply showed good results in input power $220[V]{\pm}15[\%]$ with stabilized output of power, luminous efficiency 97[1m/W] and power factor $96[\%]$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.1
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• pp.52-58
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• 2013

Operation Abstract : Operational cost required for navigating a ship may differ from according to type, scale, economic speed, navigation area and other factors. However, it is known that the fuel oil price ratio takes 50~60 %. It is the current trend because of the use of poor quality fuel and it is reviewed even for small to medium sized ships to save the operational costs due to the recent rise of international oil price. Furthermore, ocean carriers are taking action to low speed navigation as the alternative method of reducing fuel consumption. Hence, in this study, fuel consumption of main engine was measured by using actual operating ship data compared with sea speed at sea. It was suggested that the area of M/E's load(70 %) lower than NCR is the optimal navigating condition through the relation between speed and fuel consumption compared with advance ratio together with the load.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.34-37
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• 2017

This letter presents the signal processing of a CW radar (Continuous Wave or Doppler radar) sensor which enables the radar to detect the multiple targets' approaching and retreating using both I and Q channels. The proposed algorithm utilizes the phase change of the Quadrature signal, which occurs when targets move back and forth from the radar. The verification is carried out with the board containing a commercially available MMIC chip and an MCU by analyzing the received data from MMIC. Also the proposed algorithm is downloaded to MCU and the approaching and retreating movement is confirmed. The CW frequency is 24.125 GHz and the transmitter output power used is 7.2 dBm. Detectable distance is about 12 m.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.175-181
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• 2008

We develop a fiber optic acceleration sensor with LED, PD, POF, and a cantilever beam, having film grating at the edge of the beam. Light is transmitted from LED to PD through the film grating. When the cantilever beam moves by external vibration, output light is modulated as sinusoidal signals. The characteristics of output signals are dominated by the spacing of the film grating and also by the size and the elasticity of the beam. Two output signals, having constant initial phase difference, are obtained by two gratings with 90 degree phase difference. Those two signals are used to determine phase angle, which is proportional to the displacement of the beam. Finally, the acceleration is determined from conversion equation between displacement and acceleration. This sensor is designed for monitoring the vibration of large and complex building in the low frequency range of below 7 Hz, and is particularly suitable to measure acceleration in electromagnetic environments.

• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.257-262
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• 2001

A Littman type tunable external-cavity diode laser system was developed. The laser output which is the Oth-order diffracted beam from a diffraction grating in an external cavity is a single longitudinal mode. Its FWHM was measured as less than 9 MHz. With the diode driving current of 140 mA and operating temperature of $25^{\circ}C$, the coarse tuning range of 3.475 urn was measured. A fine tuning experiment in which an external mirror was rotated by a PZT driven by a sawtooth wave was performed, and its tuning range of 0.042 urn was measured. sured.

• Journal of the Korean Society of Radiology
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• v.4 no.3
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• pp.31-37
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• 2010

In this paper, a photovoltaic system is designed with PWM(Pulse Width Modulation) voltage source inverter. Proposed synchronous signal and control signal was processed by 56F8323 microprocessor for stable modulation. The PWM voltage source inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power, from 10 to 20[%]. The PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In addition, I connected extra power to the system through operation the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and PWM voltage inverter can be synchronized. In the system of this research showed good results after being controlled in order to provide stable power to the load and the system through maintaining and low output power of harmonics.