• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2221-2229
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• 2022

In this research, for improving the measurement performance of Prompt Gamma-ray Neutron Activation Analysis (PGNAA) set-up, a new optimization method for set-up design was proposed and investigated. At first, the calculation method for Signal-to-Noise Ratio (SNR) was proposed. Since the SNR could be calculated and quantified accurately, the SNR was chosen as the evaluation parameter in the new optimization method. For discussing the feasibility of the SNR optimization method, two kinds of PGNAA set-ups were designed in the MCNP code, based on the SNR optimization method and the previous signal optimization method, respectively. Meanwhile, the single element spectra analysis method was proposed, and the analysis effect of single element spectra as well as element sensitivity were used for comparing the measurement performance. Since the simulation results showed the better measurement performance of set-up designed by SNR optimization method, the experimental set-ups were built for the further testing, finally demonstrating the feasibility of the SNR optimization method for PGNAA setup design.

• 품질경영학회지
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• 제25권4호
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• pp.88-98
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• 1997

For quality improvement, it is important to reduce variations of the quality characteristic. That can be achieved by the a, pp.ication of parameter design methodology to make the performance of the quality characteristic robust over the variety of noise conditions. Taguchi has used the signal-to-noise ratios for that purpose. For the static target characteristic and the dynamic characteristic problem, we propose a reasonable generalized SN ratio and p-value plot for identifying dispersion factors. The orginal idea of the p-value plot in from the gamma-plot in Lunani, Nair & Wasserman(1995). The graphic advantage of the p-value polt for identifying dispersion factors is illustrated through constructed examples.

• 한국안전학회지
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• 제21권1호
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• pp.114-119
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• 2006

In this study, laminated composite umbrella type roofs structures such as stadium, exhibition, auditorium and museum are analyzed. These structures have not been dealt with so far because of the difficulty in modeling. These have been analyzed mostly by a simplified method or a grid analysis in design. In this study, better results can be obtained by using shell element. The behavior of umbrella type shell roof under self weight is analyzed for various parameters such as the influence of diaphragm, diaphragm type, ${\gamma}-angle$ type, height/chord ratio of segment, slope of roofs, number of conical segment and subtended angle.

• 제어로봇시스템학회논문지
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• 제4권2호
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• pp.170-177
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• 1998

In this paper, a unified solution of Hankel norm approximation problem is proposed by $\delta$-operator. To derive the main result, all-pass property is derived from the inner and co-inner property in the $\delta$-domain. The solution of all-pass becomes an optimal Hankel norm approximation problem in .delta.-domain through LLFT(Low Linear Fractional Transformation) inserting feedback term $\phi(\gamma)$, which is a free design parameter, to hold the error bound desired against the variance between the original model and the solution of Hankel norm approximation problem. The proposed solution does not only cover continuous and discrete ones depending on sampling interval but also plays a key role in robust control and model reduction problem. The verification of the proposed solution is exemplified via simulation for the zero-order Hankel norm approximation problem and the model reduction problem applied to a 16th order MIMO system.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1427-1439
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• 2008

The quality of track-bed fills of railways has been controlled by field measurements of density (${\gamma}_d$) and the results of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures is that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. A new quality control procedure, in parallel with the advent of the new design procedure, is being proposed. This procedure is based upon P-wave velocity involving consistently the evaluation of design parameters in design stage and the field measurements during construction. The key concept of the procedure is that the target value for field compaction control is the P-wave velocity determined at OMC using modified compaction test, and direct-arrival method is used for the field measurements during construction. The procedure was verified at a test site and the p-wave velocity turned out to be an excellent control measure. The specifications for the control also include field compaction water content of $OMC{\pm}2%$ as well as the p-wave velocity.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.245-251
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• 2005

연안 및 항만시설물의 설계에서 심해 설계파 및 풍속은 매우 중요한 설계 파라메타이다. 특히, 최근 부각되고 있는 방재공학 측면에서 이러한 정보에 대한 분석단계는 필수적이라 할 수 있다. 본 연구에서는 완도관측소의 기상연보에서 제시한 1978년부터 2003년까지의 풍속자료와 한국해양연구원 파랑정보시스템에서 제공하는 16방향별 최대 유의파 산출자료를 이용하여 극치분석을 수행하였다. 특성분석에 사용된 극치분포함수는 Weibull, Gumbel, Log-Pearson Type-III, Normal, Lognormal, Gamma 분포이며, 각 분포함수의 매개변수는 모멘트법, 최우도법 그리고 확률 가중 모멘트법으로 추정하였다. 또한, 극치분포함수의 적함성은 5${\%}$의 유의수준 즉, 95${\%}$신뢰도 수준으로 $x^{2}$및 K-S 검정을 실시하였다. 그 결과, 한국 남서연안의 심해 설계파고는 Gumbel 분포형이 가장 적합한 모형으로 파악되었으나, 본 연구의 대상영역에 적합한 모형은 각각의 극치자료에 따라 선정된 확률분포에 의해 다르게 나타났다.

• 한국해안·해양공학회논문집
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• 제20권4호
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• pp.342-354
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• 2008

다양한 파랑 관측 및 후측 자료를 이용하여 한국 연안의 심해파 통계 특성을 연구하였다. 설계파에 준하는 큰 파랑에 대해서는, 유의파고와 유의파주기 사이의 관계에 대하여 1977년 Shore Protection Manual 공식과 2003년 Goda 공식의 평균값을 사용하는 것이 바람직하다. 일정한 유의파고에 대하여 평균값으로 무차원화 시킨 유의파주기의 표준편차는 해역과 유의파고의 범위에 따라 0.04부터 0.21까지 변하며 전형적인 값은 0.1이다. 한반도 주변 106개 연안 격자점에서의 심해 주파향의 평균과 표준편차를 제시하였다. 비교적 큰 파랑에 대한 방향분산계수 $s_{max}$의 확률밀도함수는 대수정규분포로 표시된다. 우리나라 연안에서 가장 적합한 주파수 스펙트럼은 TMA 스펙트럼이다. 스펙트럼 첨두증대계수 $\gamma$의 확률밀도함수 또한 대수정규분포로 표시되며, 북해에서의 값과 비슷한 2.94의 평균값을 보인다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.361-366
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• 2006

본 연구에서는 초음속 충동형 터빈의 유동특성을 알아보기 위해 소형 초음속 풍동을 설계하였으며 Schlieren system을 이용하여 유동을 가시화하였고 압력변환기를 이용하여 터빈내의 전압력과 정압력을 측정하였다. 실험은 2차원 초음속 노즐과 익렬을 조합하여 익렬 앞전 모서리각에 따라 실시하였다. 그리고 이를 통해 충격파를 포함한 복잡한 유동 형태와 노즐-익렬, 충격파-경계층 상호작용 등, 초음속 충동형 터빈의 유동특성을 관찰할 수 있었다.

• 대한기계학회논문집
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• 제14권2호
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• pp.339-348
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• 1990

Techniques which are able to predict and control dynamic characteristics, not affecting the vibrational characteristics on the modification of structural design, are being studied. As one of these techniques, experimental modal analysis is widely applied by many researchers. In this study, modal analysis is performed using transfer matrix method by a macro computer. The developed program would estimate the structural modal parameters precisely, and the validity of this program is certified by comparing with the experimental results of .GAMMA A. structure. Estimated modal parameters(natural frequency, vibrational mode, equivalent mass, etc.) are in accord with the experimental results. Also, the optimal location of the additive mass is determined by the evaluation of the vibrational mode and the equivalent mass. The relation between the additive mass and the equivalent mass is specified, and we come to know that the ratio of equivalent mass to additive mass alter linearly within the range of 20%.

• 한국항해항만학회지
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• 제36권9호
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• pp.729-735
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• 2012

The primary wave energy conversion by a three-dimensional bottom-mounted oscillating water column (OWC) wave power device in regular waves has been studied. The linear potential boundary value problem has been solved following the boundary matching method. The optimum shape parameters such as the chamber length and the depth of the front skirt of the OWC chamber obtained through two-dimensional numerical tests in the frequency domain have been applied in the design of the present OWC chamber. Time-mean wave power converted by the OWC device and the time-mean second-order wave forces on the OWC chamber structure have been presented for different wave incidence angles in the frequency-domain. It has been shown that the peak period of $P_m$ for the optimum damping parameter coincides with the peak period of the time.mean wave drift force when ${\gamma}=0$.