• Structural Engineering and Mechanics
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• 제9권3호
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• pp.257-268
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• 2000

The seismic design recommendations of the Jordan Code for Loads and Forces (JC) are evaluated, based on comparisons with analytical studies and the Uniform Building Code. It was established that the overall safety ensured by the implementation of these recommendations is not consistent with the established seismic risk in Jordan and the intended objectives of the code. A new zoning map is proposed with effective peak ground acceleration values. The different period formulae of the code were studied and were found to grossly underestimate the fundamental period when compared with analytically derived values or other codes' formulae. Other factors including the dynamic, soil, importance and behavior factors are discussed. It was determined that the JC's lateral load distribution formulae clearly lead to smaller internal forces than both dynamic analysis and UBC loads, even when those loads are normalized to give the same base shear. The main reason for this is attributed to the limited allowance for a backlash force in the JC.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.657-662
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• 1996

Venting capability to prevent excess pressurization caused by loss of Residual Heat Removal System (RHRS) during mid-loop operation hat been evaluated analytically and the peak Reactor Coolant System (RCS) pressure was compared with the results of the MIDLOOP computer code. Even though analytical method if relatively simple, the results are in a good agreement with those of the computer code. For both methods, the peak pressures have not, exceeded the nozzle dam design pressure, if the vent paths such as pressurizer safety valves or a pressurizer manway are available in a closed RCS configuration with the nozzle dam installed.

• 정보처리학회논문지C
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• 제12C권6호
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• pp.901-906
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• 2005

본 논문에서는 초고속 전승을 위해 제안된 HCOC(High Capacity Orthogonal Code) 대역확산(Spread Spectrum) 시스템의 높은 PAPR(Peak power to Average Power Ratio)을 줄여주는 새로운 MHCOC (Mapped HCOC) 대역확산 기술을 제안하고, 같은 비트 수를 전송할 수 있는 기존의 MQAM 대역확산 시스템과 비교 분석한다. 또한 전송 채널의 상황에 따라 알맞은 데이터 서비스를 하는 QoS (Quality of Service)를 만족시키기 위해 제안한 시스템의 적응성에 대하여 연구한다. 컴퓨터 시뮬레이션을 통하여 제안한 시스템의 성능을 평가 및 분석하고, 기존의 시스템과 비교 분석한다.

• 한국통신학회논문지
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• 제26권12B호
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• pp.1637-1647
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• 2001

Multi-Code CDMA (MC-CDMA) 방식은 송신 시 여러 채널의 신호를 동시에 선형적으로 합하여 전송하므로 채널수가 증가할수록 신호의 PAPR(Peak to Average Power Ratio)가 증가하게 되어 증폭기의 비선형 특성에 의해 시스템 성능이 변화한다. 본 논문에서는 다중 레벨 신호에 대한 증폭기의 비선형 왜곡 특성을 분석하고, 증폭기의 비선형 특성에 의한 영향을 최소화하기 위해 다중 레벨 신호를 constant envelope 신호로 변환하는 Multi-Phase CDMA (MP-CDMA) 방식을 제안한다. 또한 다중 레벨 신호의 일정 레벨 이상은 잘라버리는 clipping 방식을 적용함으로써 레벨수의 증가에 따른 성능 저하 및 시스템의 복잡화를 줄이며 이로 인한 시스템 성능의 변화와 요구 전송 속도에 따른 최적의 clipping level을 연구한다.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1698-1711
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• 2022

A combined safety approach, which uses a best-estimate computer code and adopts conservative assumptions for safety systems availability, is developed and applied to the safety margin evaluation for the Loss of Condenser Vacuum (LOCV) of the 1000 MWe Korean Nuclear Power Plant. The Multi-dimensional Analysis of Reactor Safety-KINS standard (MARS-KS) code is selected as a best-estimate code and the PAPIRUS program is used to obtain different initial operational conditions through random sampling of control variables. During an LOCV event, fuel integrity is not threatened by the increase in Departure from Nuclear Boiling Ratio (DNBR). However, the high pressure in the primary coolant system and the secondary system might affect the system integrity. Thus, the peak pressure becomes a major safety concern. Transient analyses are performed for 124 cases of different initial conditions and the most conservative case, which results in the highest system pressure is selected. It is found the suggested methodology gives similar peak pressures when compared to those predicted from existing methodologies. The proposed approach is expected to minimize the time and efforts required to identify the conservative plant conditions in the existing conservative safety methodologies.

• 한국통신학회논문지
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• 제36권9C호
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• pp.581-588
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• 2011

본 논문에서는 cosine 위상 binary offset carrier (BOC) 신호를 위한 코드 추적 기법을 제안한다. BOC 자기상관함수는 다수의 부상관함수들로 이루어져 있으며, 본 논문에서는 이러한 부상관함수들을 재결합함으로써 주변첨두가 없는 새로운 상관함수를 획득한다. 마지막으로 delay lock loop 에서 사용되는 자기상관함수를 제안한 상관함수로 대체함으로써 주변첨두로 인한 false lock 문제를 해결한다. 또한 모의실험 결과를 통해 제안한 기법이 기존의 기법에 비해 더 좋은 tracking error standard deviation (TESD) 성능을 가지는 것을 보인다.

• 한국전자파학회논문지
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• 제16권7호
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• pp.690-696
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• 2005

PAPR(Peak to Average Power Ratio)를 줄이는 것은 OFDM(Orthogonal Frequency Division Multiplexing) 통신 시스템에서 매우 중요하다. 본 방법은 Golay상보 부호에 의한 PAPR 감소 기법의 한 가지 방법으로서,부가 신호를 사용하지 않으면서 효과적으로 PAPR을 감소시킬 수 있는 방법이다. 기존의 상보 부호에 의한 PAPR의 감소기법은 오류 정정 부호를 사용하거나 부가 신호를 사용 데이터 전송율이 감소하게 된다 있다. 본 논문에서는 단지 복수위상 상보부호를 이용하여 4-QAM의 성상도를 16-QAM의 형태로 변환하고 부가신호의 추가 및 부호율 증가에 영향을 주지 않는 PAPR감소 기법을 제안한다.

• 한국위성정보통신학회논문지
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• 제7권3호
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• pp.26-29
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• 2012

본 논문에서는 상향링크에서 낮은 PAPR(Peak to Average Power Ratio)을 가지면서 사용자 간 동기 오차 범위를 크게 확장한 MCDS CDMA(Multiple Carrier Direct Spread Code Division Multiple Acceess) 형태의 SC-FDMA(Single Carrier Frequency Division Multiple Access) 기법을 제안한다. 제안하는 기법은 상향링크 준동기 환경에 강한 특성을 가진 MC DS CDMA 기법의 높은 PAPR을 갖는 단점을 보완하기 위해 부분 IFFT(Inverse Fast Fourier Transform) 연산 이전에 부분 DFT(Discrete Fourier Transform)연산을 수행한다. 제안하는 기법은 ${\pm}1$칩 준동기 상황에서 '0'상관도를 갖는 PSW(Properly Scrambled Walsh) 부호를 시간 도메인으로 스프레딩하여 레인징 절차를 수행하지 않고서도 사용자 간 최대 ${\pm}1$ OFDM 심벌 길이 이내의 시간 오차이내에서는 MAI(Multiple Access Interference)가 발생하지 않게 한다. 실험결과에서는 준동기 상황을 개선하기 위해 제안된 기존의 SC-FDMA 방식에 비해 사용자 간 동기 오차에 강한 특성이 있음을 보인다.

• Earthquakes and Structures
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• 제3권5호
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• pp.719-747
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• 2012

In this paper a novel approach is proposed to address the problem of deriving non-stationary stochastic processes which are compatible in the mean sense with a given (target) response (uniform hazard) spectrum (UHS) as commonly desired in the aseismic structural design regulated by contemporary codes of practice. The appealing feature of the approach is that it is non-iterative and "one-step". This is accomplished by solving a standard over-determined minimization problem in conjunction with appropriate median peak factors. These factors are determined by a plethora of reported new Monte Carlo studies which on their own possess considerable stochastic dynamics merit. In the proposed approach, generation and treatment of samples of the processes individually on a deterministic basis is not required as is the case with the various "two-step" approaches found in the literature addressing the herein considered task. The applicability and usefulness of the approach is demonstrated by furnishing extensive numerical data associated with the elastic design UHS of the current European (EC8) and the Chinese (GB 50011) aseismic code provisions. Purposely, simple and thus attractive from a practical viewpoint, uniformly modulated processes assuming either the Kanai-Tajimi (K-T) or the Clough-Penzien (C-P) spectral form are employed. The Monte Carlo studies yield damping and duration dependent median peak factor spectra, given in a polynomial form, associated with the first passage problem for UHS compatible K-T and C-P uniformly modulated stochastic processes. Hopefully, the herein derived stochastic processes and median peak factor spectra can be used to facilitate the aseismic design of structures regulated by contemporary code provisions in a Monte Carlo simulation-based or stochastic dynamics-based context of analysis.

• Earthquakes and Structures
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• 제3권3_4호
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• pp.581-609
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• 2012

In this paper a novel non-iterative approach is proposed to address the problem of deriving non-stationary stochastic processes which are compatible in the mean sense with a given (target) response (uniform hazard) spectrum (UHS) as commonly desired in the aseismic structural design regulated by contemporary codes of practice. This is accomplished by solving a standard over-determined minimization problem in conjunction with appropriate median peak factors. These factors are determined by a plethora of reported new Monte Carlo studies which on their own possess considerable stochastic dynamics merit. In the proposed approach, generation and treatment of samples of the processes individually on a deterministic basis is not required as is the case with the various approaches found in the literature addressing the herein considered task. The applicability and usefulness of the approach is demonstrated by furnishing extensive numerical data associated with the elastic design UHS of the current European (EC8) and the Chinese (GB 50011) aseismic code provisions. Purposely, simple and thus attractive from a practical viewpoint, uniformly modulated processes assuming either the Kanai-Tajimi (K-T) or the Clough-Penzien (C-P) spectral form are employed. The Monte Carlo studies yield damping and duration dependent median peak factor spectra, given in a polynomial form, associated with the first passage problem for UHS compatible K-T and C-P uniformly modulated stochastic processes. Hopefully, the herein derived stochastic processes and median peak factor spectra can be used to facilitate the aseismic design of structures regulated by contemporary code provisions in a Monte Carlo simulation-based or stochastic dynamics-based context of analysis.