• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.58-63
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• 2010

In this paper, we propose a simple technique for the detection of a frequency jump in the GPS clock behavior. GPS satellite atomic clocks have characteristics of a second order polynomial in the long term and a non-periodic frequency drift in the short term, showing a sudden frequency jump occasionally. As satellite clock anomalies influence on GPS measurements, it requires to develop a real time technique for the detection of the clock anomaly on the real-time GPS precise point positioning. The proposed technique is based on Teager energy which is mainly used in the field of various signal processing for the detection of a specific signal or symptom. Therefore, we employed the Teager energy for the detection of the jump phenomenon of GPS satellite atomic clocks, and it showed that the proposed clock anomaly detection strategy outperforms a conventional detection methodology.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.5
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• pp.396-401
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• 2017

In this paper, we propose a solution for interference with Bluetooth when connecting Bluetooth and other devices. The random frequency hopping technique is a technique of generating a hopping pattern using the entire Bluetooth channel without considering the interference of the wireless LAN. The proposed adaptive frequency hopping technique is a technique for generating a hopping pattern of Bluetooth channel considering periodic carrier sensing of Bluetooth and considering WLAN interference. Simulation results show that the use of adaptive frequency hopping reduces the packet error rate as the Bluetooth carrier sensing interval decreases even in the congestion of WLAN interference. Especially, the frequency hopping technique improves the average packet error rate by about 13% compared to the adaptive frequency hopping technique.

• Journal of KSNVE
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• v.6 no.4
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• pp.439-446
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• 1996

This paper introduces a newly designed pendulum system that enables the more accurate boservation of dynamic behaviour arising from both horizontal and vertical(i.e. two dimension) excitation. First, experiments were carried out to examine the frequency responses of the devised pendulum system. Interestingly, experimental results for the three excitation angles of 22, 32 and 48 degree show 'new' jump phenomena. For the further understanding of these phenomena, experimental investigationhas been made to identify the equation of motion of the pendulum system from experimental data. This attempt has revealed that the viscous, coulomb and aerodynamic damping factors are involved in the equation of motion. By applying the Ritz averaging method to the equation, it becomes apparent that the jumping phenomena of the pendulum system in this work is more theoretically understood.

• Journal of Technology Innovation
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• v.1 no.1
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• pp.84-99
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• 1993

오래도록 생산성향상곡선 (또는 학습곡선), 생산함수, 그리고 대체곡선 등은, 서로 관련이 없는 별개의, 그리고 순전히 경험적인 (empirical) 현상들인 것들로서 이해되어 왔었다. 그러나 1980년대 중반에 발표된 Muth 교수의 탐색이론 (Search Theory)의 생산성향상곡선에서 관찰된 제반현상들을 모두 설명함으로써 이들 현상은 하나의 통합이론체계에 의하여 일관되게 설명되게 되었다. 이 이론의 초기형태는 그 보편성을 구속하는 네 가지 가설 위에 설립되었었으나 점차적으로 이들 가설들이 완화되면서 (relaxed) 이 이론은 또한 해독 력에서 뿐만 아니라 일반성에 있어서도 계속 강화되어 왔다. 본 논문의 목적은, 이들 네 가지 가설들 중 유일하게 아직 완화되지 못하고 있는, 실제 현상과 다분히 유리된, 두 번째 가설, 즉$\ulcorner$생산성향상을 위한 탐색과정에서 새로이 발견된 개량 신기술 (또는 생산방식) 은 즉각적으로 채택될 것$\lrcorner$이라는 가설을 완화함으로써, 보다 현실에 대한 해석력과 일반성 면에서 개선된 모델을 제시하는 데 있다. 이를 위하여 제시된 모델은 Muth 교수의 탐색이론모델에 두가지 변수를 더함으로써 확장하여 만든 모델이다. 이 두 변수는 신기술의 채택 (또는 획득)을 위하여 지불하여야 하는 투자비변수와 탐색과정을 통하여 발견은 되었으나 아직 채택은 되지 않은, 유보상태 신기술의 운영비용 변수(또는 수익성변수)등이다. 이 모델의 내용은, 생산성향상은 신기술이 구현된 (embodied) 장비 (equipment)를 사용함으로써 실현되며, 따라서 창의적 활동의 이득은 이들 장비에 대한 투자행위로서 실현된다는 것이다. 이 모델은 보다 나은 신기술이 또 발견될 것이라는 기대 하에, 현재 발견된 최신기술을 채택하지 않는 투자지연현상을 예측.설명해 주며 따라서 이로 인한 기술적 비효율성의 존재이유를 제시한다. 또한 이 모델은 생산성 향상곡선의 초기굴곡현상, 정체현상, 그리고 도약현상 등을 모두 설명해 준다.

• The monthly packaging world
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• s.40
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• pp.104-107
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• 1996

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.124-127
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• 2003

본 논문에서는 초광대역 무선 통신에 안티포달 펄스 신호를 이용하고, 기존의 초광대역 시간도약 모노펄스 통신에서 규칙적인 펄스를 전송할 때 발생하는 전력 스펙트럼에서의 에너지 스파크 현상을 완화시키기 위하여 의사잡음 부호와 왈쉬 부호를 사용하였을 때의 전력 스펙트럼 특성을 비교, 분석하였다. 그 결과, 초광대역 안티포달 임펄스 통신에서의 두 가지 부호 방식의 이용으로 에너지 스파크 현상이 완화되고 고속의 시간도약 부호를 이용하지 않더라도 완만한 전력스펙트럼 특성을 얻을 수 있었다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.445-451
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• 2005

This paper is the result of a experimental study about non-linear one to one modal coupling of a flexible circular cantilever beam which was transversely excited with harmonic excitation. It was proved that 2 order jumping in out of plane was caused by jump phenomenon in in-plane of flexible circular cantilever beam, because of non-linear coupling. In addition, cantilever beam showed hardening spring characteristics in in-plane and softening spring characteristics in out-of-plane.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1103-1108
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• 2010

In this paper, Frequency Synthesizer which is widely used for FH-SS system is proposed and the experimental results are analyzed. The performance of the DPLL(Digital Phase-Locked-Loop), which is the main part of the Synthesizer is analyzed by the computer program. Using Maxplus-II tool provided by altera. co., ltd, each part of the DPLL is designed and all of them is integrated into EPM7064SLC44-10 chip. And the simulation results are compared with the characteristics of the implemented circuits for analysis. And the experiential results show that the N value of the loop filter is toggled to adjacent N value, which result in phase jitter of the output. It can be resolved by increasing DCO(Digital Controlled oscillator) clock rate.

• Korean Journal of Optics and Photonics
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• v.23 no.2
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• pp.77-86
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• 2012

The connection between the continuousness of Rabi oscillation and the discontinuity of quantum jumps has long remained one of the conceptual difficulties since the discovery of the quantum physical paradigm. In this study, however, we demonstrate that the behavior of the atom-field composite system gradually changes from the continuous Rabi interaction to the discontinuous quantum jumps as the atom-field coupling strength is reduced. The reduction occurs through enlarging the quantization volume of the mode so that the mode approaches one of the infinitely many modes of the thermal background.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.255-260
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• 2015

Flash evaporation phenomenon is affected by temperature, pressure and water level in the open chamber and Baffle etc. In this study, PIV experiments were conducted to ensured the flow Characteristics in the open chamber, and optimum baffle location and baffle height. Baffle had a considerable effect on the recirculation flow, hydraulic jump and the flow characteristics in the Open chamber, and influence of Reynolds number was insignificant. The optimum baffle height was about h/H=1.5. and optimum baffle location was x/H=1.5 from the inlet of open chamber.