• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.61-62
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• 2012

The present study has numerically investigated the effects of fuel-side dilution and pressure on flame structure and extinction scalar dissipation rate of turbulent syngas nonpremixedd flames. Numerical results indicate that for highly diluted case, peak temperature is decreased and stoichiometric mixture fraction is increased. By decreasing the pressure and the nitrgen dilution levelcreased, the extinction scalar dissipation rate is increased.

• 제어로봇시스템학회논문지
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• 제22권12호
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• pp.991-994
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• 2016

This paper presents a load management method based on OpenADR of smart grid. Previous demand side algorithm is restricted on reducing peak power. But, in this paper we suggest a method of performing the energy-saving control according to the power price utilizing building automatic control system installed on the customer side in the case of hourly differential pricing signal is transmitted to the open automated demand response system. And, we showed the integrated demand management software for 3 buildings.

• Geomechanics and Engineering
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• 제13권3호
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• pp.411-429
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• 2017

A Spectral Element Method for 3D seismic wave propagation simulation is derived based on the three-dimensional fluctuating elastic dynamic equation. Considering the 3D real terrain and the attenuation characteristics of the medium, the topographic effect of Wenchuan earthquake is simulated by using the Spectral Element Method (SEM) algorithm and the ASTER DEM model. Results show that the high PGA (peak ground acceleration) region was distributed along the peak and the slope side away from the epicenter in the epicenter area. The overall distribution direction of high PGA and high PGV (peak ground velocity) region is parallel to the direction of the seismogenic fault. In the epicenter of the earthquake, the ground motion is to some extent amplified under the influence of the terrain. The amplification effect of the terrain on PGA is complicated. It does not exactly lead to amplification of PGA at the ridge and the summit or attenuation of PGA in the valley.

• 한국통신학회논문지
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• 제33권4A호
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• pp.467-472
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• 2008

One of the maindisadvantages of Orthogonal Frequency Division Multiplexing (OFDM) is the Peak to Average Power Ratio (PAPR) problem. To reduce PAPR and improve the error performance of the OFDM signal over a fading channel, an OFDM system combining an Adaptive Symbol Selection Scheme (ASSS) and channel estimation can be used. Because of the side information of ASSS, however, the data rate decreases in the conventional ASSS OFDM system. In this letter, to overcome this impairment, we propose a technique to transmit side information by using pilot tones, and demonstrate that the proposed technique can give reasonable bit error rate (BER) performance.

• 열처리공학회지
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• 제24권6호
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• pp.311-317
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• 2011

The effect of strain rate on the yield stress of an Al-Li alloy has been investigated at temperatures between 77 and 523 K and over the strain rate range from $1.77{\times}10^{-4}s^{-1}$ to $1.77{\times}10^{-2}s^{-1}$. At testing temperatures below 373 K, the yield stress is almost independent of strain rate at any aging stage. At testing temperatures above 373 K, the yield stress increases linearly with the logarithm of strain rate, and the strain rate dependence increases with increasing testing temperature. The yield stresses of under-aged alloy at temperatures between 373 and 473 K at high strain rates are greater than the yield stress at 77 K. For the alloy under-aged or aged nearly to its peak strength, the temperature range within which the positive temperature dependence of yield stress appears expands to the higher temperature side with increasing strain rate. The strain rate dependence of the yield stress is slightly negative at this aging stage. The yield stress of the over-aged alloy decreases monotonically with decreasing strain rate and with increasing testing temperature above 373 K. The modulus normalized yield stress is nearly constant at testing temperatures below 373 K at any strain rate investigated. And, strength depends largely both on the aging conditions and on the testing temperature. The peak positions in strength vs. aging time curves shift to the side of shorter aging time with increasing testing temperature. For the specimens aged nearly to the peak strength, the positive temperature dependence of yield stress is observed in the temperature range. The shift of peak positions in the aging curves are explained in terms of the positive temperature dependence of cutting stress and the negative temperature dependence of by-passing stress.

• PNF and Movement
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• 제17권2호
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• pp.263-274
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• 2019

Purpose: This article was conducted to determine the immediate effects of unilateral contract-relax (CR) stretching on contralateral knee extension range and to compare both sides of the knee extension range between experimental and control groups. Methods: This study recruited 16 adult males and females with straight leg raising abilities below $90^{\circ}$. The subjects were randomly divided into an experimental group and a control group comprising 8 subjects each. The experimental group performed direct CR stretching on the right hamstring muscles with straight hip extension adduction, and the control group performed indirect CR stretching on the right hamstring muscles with straight hip flexion abduction. Each group performed CR stretching 4 times with 4 repetitions comprising 10 sec of contraction and a 10 sec break between repetitions. Before and after the CR stretching exercises, the subjects' passive knee extensions were measured at the hip in a $90^{\circ}$ flexed position. The subjects' peak force on the right leg and peak pressure on the left leg during each CR stretching exercise were also measured. Results: After doing CR stretching 4 times, each group showed a significantly increased passive knee extension range on both sides, and there was no difference in the passive knee extension ranges between the groups. The peak force on the right leg was significantly higher in the experimental group than the control group. There was no difference in peak pressure between the groups. Conclusion: After applying unilateral CR stretching, the study subjects experienced a significantly increased passive knee extension range on the contralateral side. For patients who find it difficult to apply stretching techniques to knee joints directly, the use of the proprioceptive neuromuscular facilitation technique of CR stretching may be useful in improving the range of the knee joint on the contralateral side without direct treatment.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.55-60
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• 2004

In this study, the configuration and tension of a towing cable for side-scan sonar are predicted in an ambient flow and at an unsteady towing condition. The governing equation of three-dimensional dynamic analysis for a flexible cable is solved using a finite difference method. We successfully predict the configuration and tension of a side-scan sonar and designed the towing system. It is found in static analyses that the side-scan sonar must be towed to keep a its stable depth at a reasonable speed. The study also reveals in the transient analyses that the dominant component affecting the top tension is the tangential drag force for the larger towing speed than the critical speed, and the self weight of a towed instrument for the smaller towing speed than. It should be maneuvered for a towing vessel with good consideration for the impact effect in a cable due to tension peak when a towing speed is suddenly increase. The developed program can be applicable for three-dimensional dynamic analysis of a towing system for various marine survey instruments.

• 전자공학회논문지
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• 제53권6호
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• pp.15-20
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• 2016

OFDM 시스템을 위한 PAPR (peak-to-average power ratio) 저감 기법 중 하나인 SLM (selective mapping) 방식은 구현이 간단하고 전송 신호에 왜곡이 생기지 않는 매우 유용한 PAPR 저감 기법이다. 본 논문에서는 위상 신호에 대한 부가 정보(side information)를 전송하지 않는 SLM 기반 OFDM 시스템에 적용 가능한 동기식 위상 신호 검출 방식을 제시하고자 한다. 우선 동기식 합(coherent summation)에 기반하여 위상 신호를 검출할 수 있도록 하기 위해, 위상 신호의 일부를 직교 부호로 대치시키는 새로운 위상 신호 설계 방법을 제안한다. 또한 새로이 제안된 위상 신호에 기초하여 부가 정보가 필요 없는 동기식 위상 신호 검출 기준(detection criterion)을 제안한다. 컴퓨터 모의실험을 통해, 제안된 방식이 SLM 기반 OFDM 시스템에서 정상적으로 동작함을 보이고, 위상 신호 검출에 사용되는 부반송파 간 채널의 변화가 적은 환경에서 기존 방식보다 위상 신호 검출 성능이 우수함을 보이고자 한다.

• 한국통신학회논문지
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• 제40권9호
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• pp.1710-1718
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• 2015

SLM(selected mapping)은 OFDM(orthogonal frequency division multiplexing)의 PAPR(peak to average power ratio)을 줄이는 효과적인 방법이다. 데이터를 복구하기 위해서 수신기는 송신기가 선택한 스크램블링 수열의 색인정보인 부가정보 SI(side information)를 알아야한다. 본 논문에서는 수신기가 SI 없이 데이터를 복원할 수 있도록 함으로써 구현 복잡도를 낮출 수 있는 새로운 SLM 방법을 제안한다. 제안된 방법에서는 다중 경로 채널과 IDFT(inverse discrete fourier transform)된 스크램블링 수열의 컨볼루션에 해당하는 가상 다중 경로 채널을 가정한다. 파일럿을 사용해 측정한 가상 채널을 바탕으로 데이터를 복원함으로써 SI 없이도 수신기가 데이터를 복원할 수 있다. 제안된 SLM 방법이 이전 SLM 방법들과 비슷한 PAPR 성능 및 BER 성능을 가짐을 모의실험을 통해 보인다.

• 대한기계학회논문집A
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• 제36권10호
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• pp.1155-1162
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• 2012

알루미늄 크래쉬 박스는 저속충돌조건에서 프론트 사이드 멤버를 변형을 방지하기 위한 부품이다. 본 연구에서는 저속충돌조건에서 비드형상이 알루미늄 크래쉬 박스의 충돌성능에 미치는 영향을 분석하였다. Edge concave, surface convex 와 surface concave 타입의 비드형상들에 대한 충돌해석 및 실험을 수행하여 비드가 없는 normal 타입의 알루미늄 크래쉬 박스의 충돌성능과 비교분석하였다. 충돌성능은 저속충돌조건에서 크래쉬 박스의 초기 최대하중 및 충돌에너지 흡수능으로 평가하였다. 이를 검증하기 위해 알루미늄 크래쉬 박스와 결합된 프론트 사이드 멤버에 대해 저속충돌실험 수행하고, 이를 분석하였다. Surface concave 타입의 비드가 삽입된 알루미늄 크래쉬 박스 경우, 프론트 사이드 멤버의 변형을 방지할 수 있음을 확인하였다.