• International Journal of Safety
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• 제9권1호
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• pp.30-34
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• 2010

A big difference is seen in the perception of self-responsibility concerning safety, as a result of my survey on the safety measures taken in the pipeline construction at workers level between Japan and Indonesia. Specifically, when an accident occurs, a worker in Indonesia will think that the responsibility depends on the person who causes it. However a worker in Japan will think that safety is can only be protected by law and regulations. There is also another difference in the understanding of construction period. It is alright in Indonesia to take 5 times longer period than it takes in Japan if the cost is less. The idea of punctual delivery is very strong in Japan. Through this survey, points which construction industry in Japan could learn from Indonesia came to surface. In addition, over the recent years, several nasty accidents at Japanese sites were caused due to human error to disregard the law. Japanese should arouse the awareness of self-responsibility in this regard. Risk management should be upon self-recognition of each individual worker in both countries. What is important is the "work attitude education", "to grow sense of self-responsibility by thinking on one's own for one's self" in the education curriculum of man to man learning as in technical educational program.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 춘계 학술대회논문집
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• pp.1-14
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• 1998

Underwater explosion properties for TNT, an ideal explosive, and DXD-04, a nonideal explosive, were numerically modeled with a one-dimensional Lagrangian hydrodynamic code. The equation of state parameters for detonation products for TNT and DXD-04 were obtained from the BKW code, assuming complete reaction. Burn of TNT was modeled by using the Chapman-Jouguet(CJ) volume burn technique, a programmed-burn technique, assuming instantaneous detonation reaction. Burn of DXD-04 was modeled by using the same technique and by using the reaction rate calibrated from two-dimensional steady-state detonation experiments. The calculations for TNT reproduced the experimental peak pressure of the shock wave propagating through water with an error of $3.0\%$ and the experimental oscillation period of the bubble formed of detonation products with an error of $2.3\%$. For DXD-04, the CJ volume burn technique could not reproduce the experimental observations. When the reaction rate calibrated from two-dimensional steady-state detonation experimental data, the calculated peak pressure was slightly higher by $7.3\%$ than the experimental data, but the calculated shock profile was in good agreement. The bubble period was reproduced with an error of $1.8\%$. These results demonstrated that underwater explosion properties for an ideal explosive can be predicted by using a programmed burn technique, and that, however, those for a nonideal explosive can be predicted only when a well-calibrated reaction rate is used.

• 전자공학회논문지S
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• 제36S권9호
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• pp.27-35
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• 1999

본 논문은 정수론에 기반하여, PN (Pseudo Noise) 확산부호를 포함한 이원부호의 위상오프셋 오류검출방법을 제안한다. 부호분할다원접속 (code division multiple access : CDMA) 이동 통신 시스템에서는 확산부호의 위상오프셋을 인용하여, 각 기지국을 구분하고 있으므로 위상오프셋을 안다는 것은 매우 중요하다. 부호의 주기가 길지 않을 경우는 한 부호와 이전된 부호 사이의 위상 오프셋은 두 부호를 비교하여 구할 수 있지만, 부호의 주기가 길어지면 이러한 방법으로는 어려움이 따른다. 제안된 방법의 오류검출실패확률 식을 유도하고 시뮬레이션 결과를 이용하여 검증한다. 그리고 회고 구현 방법에 관하여서도 논하며, 간단한 회로로 구현할 수 있음을 보인다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.2019-2022
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• 2002

This paper presents design of spreading codes for asynchronous DS-CDMA systems. We have been trying to generate maximal-period sequences based on one-dimensional maps with finite bits whose shapes are similar to piecewise linear chaotic maps. We propose an efficient search algorithm finding such mammal-period sequences. This algorithm makes it possible to find many kinds of maximal-period sequences with sufficiently long period for CDMA applications. We also investigate bit error rate(BER) in asynchronous DS-CDMA systems using the maximal-period binary sequences by computer simulations.

• KDI Journal of Economic Policy
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• 제32권4호
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• pp.35-73
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• 2010

본고는 자산가격의 변동에 따른 민간소비의 동태적 반응을 분석한다. 오차수정모형에 기초한 분석 결과, 민간소비는 자산가격의 변화에 영향을 받지만 2년 정도의 기간이 경과할 경우 총소득에 상응하는 장기균형수준으로 수렴할 가능성이 높게 나타난다. 이러한 민간소비의 조정은 일시적인 소비불균형을 의미하는 공적분오차가 장기소비증가율에 대해 예측력을 가짐을 시사하는데, 최대 3년 정도의 장기소비증가율에 대해 예측력이 있음을 확인할 수 있다. 한편, 민간소비에 대한 영향은 주식가격보다는 주택가격이 상대적으로 더 크고 유의하게 관찰된다. 또한 경기순환을 고려할 경우 소득 및 자산가격의 변화에 대한 민간소비의 단기적인 반응은 경기수축기가 경기확장기보다 크게 추정되었다. 본고에서는 민간소비에 대한 자산가격의 영향과 더불어 수량요인까지 함께 고려한 자산의 변화가 민간소비에 미치는 영향도 구분하여 분석하였다. 분석 결과, 자산의 경우는 장기에서도 총소득과 함께 민간소비에 대해 유의한 설명력을 보인다. 한편, 전체 부를 인적요소인 노동소득과 자산으로 구분하여 자산의 변화에 따른 민간소비의 변화를 추정하였는데, 자산에 대한 소비의 장기탄력성은 노동소득을 고려한 경우가 총소득을 통제한 경우에 비해 높게 나왔다. 노동소득을 고려한 경우 자산에 대한 한계소비성향은 2% 정도로 추정된다. 이는 1,000원의 자산증가에 대해 20원 정도의 소비증대 효과가 있음을 시사한다.

• Journal of Astronomy and Space Sciences
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• 제27권1호
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• pp.31-42
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• 2010

We developed a computer program to predict solar interference period. To calculate Sun's position, we used DE406 ephemerides and Earth ellipsoid model. The Sun's position error is smaller than 10arcsec. For the verification of the calculation, we used TU media ground station on Seongsu-dong, and MBSAT geostationary communication satellite. We analysis errors, due to satellite perturbation and antenna align. The time error due to antenna align has -35 to +16 seconds at $0.1^{\circ}$, and -27 to +41 seconds at $0.25^{\circ}$. The time errors derived by satellite perturbation has 30 to 60 seconds.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.476-478
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• 1997

A new speed detection method using low resolution incremental encoders, especially excellent in the low speed region and in the transient state, is proposed. The half period error of an incremental encoder is greater than the period error. So it's not recommended to quadruple the number of pulses per revolution, because it increase the ripple of speed. To overcome this restriction a speed detection, method has been proposed. But it requires so many latch circuits. Therefore we propose a new speed detection method that has different concept and has fewer latch circuits.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.371-376
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• 1999

Stick-slip friction is present to some degree in almost all actuators and mechanisms and is often responsible for performance limitations. Simulation of stick-slip friction is difficult because of strongly nonlinear behavior in the vicinity of zero velocity. A straightforward method for representing and simulating friction effects is presented. True zero velocity sticking is represented without equation reformulation or the introduction of numerical stiffness problems. Stick-slip motion is investigated experimentally, and the fundamental characteristics of the stick-slip motion are clarified. Based on these experimental results, the characteristics of static in the period of stick and kinetic friction in the period of slip are studied concretely so as to clarify the stick-slip process.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.376-379
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• 2004

Operational orbit determination (OOD) depends on the capability of generating accurate prediction of spacecraft ephemeris in a short period. The predicted ephemeris is used in the operations such as instrument pointing and orbit maneuvers. In this study the orbit prediction problem consists of the estimating diverse arc length orbit using GPS navigation data, the predicted orbit for the next 48 hours, and the fitted 30-hour arc length orbits of double differenced GPS measurements for the predicted 48-hour period. For 24-hour orbit arc length, the predicted orbit difference from truth orbit was 205 meters due to the along-track error. The main error sources for the orbit prediction of the Low Earth Orbiter (LEO) satellite are solar pressure and atmosphere density.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.509-513
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• 2002

This paper presents a semi-blind Minimum Mean Square Error (MMSE) beamforming adaptive algorithm used far OFDM/CDMA combined system. The proposed algorithm exploits the transmitting pilot signal in the initial period of the transmission to update the weight vector. Then it applies the blind adaptive period to update the weight vector, in which the pilot signal is no longer used. The derivation of the algorithm based on the Mean Square Error (MSE) criterion is also presented. Computer simulation is carried out to verify the performance of the proposed approach.