• Journal of Power System Engineering
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• v.1 no.1
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• pp.80-90
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• 1997

The purpose of this study is to evaluate the validity examination of the J-R curve characteristics for the nuclear reactor pressure vessel steels and Al alloys by the load ratio analysis. The results of the load ratio analysis are compared with those of the J-R curve which are obtained by the ASTM unloading compliance method. The crack length calculated by the load ratio analysis is agree well with the measured final crack length. The slope of the exponential J-R curve estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method. The J-R curve obtained by the ASTM unloading compliance method is over-predicted and should be offsetted due to the initial negative crack. On the other hand, the load ratio analysis method can evaluate the J-R curve by only load-displacement curve without particular crack measurement equipment.

• Nuclear Engineering and Technology
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• v.2 no.4
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• pp.229-239
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• 1970

Various thermoluminescent properties of Korean natural quartz for possible use in ${\gamma}$-ray dosimetry has been studied. If the heating is exactly linear, ${\gamma}$-irradiated radiation sensitive (type 1) $\alpha$-quartz can yield a glow curve of single peak, hence glow peak height could be taken as a ${\gamma}$-dose for its dosimetry. Quartz crystal dosimeter exhibited the linearity of thermoluminescent intensity in the range from about 2$\times$10$^{3}$R to 2$\times$10$^{6}$ R, and also had an advantage of low fading because of the high peak temperature (300$\pm$4$0^{\circ}C$). The pulverized quartz sample having the grain size of 0.3<ø<0.9mm showed the linearity of T. L. intensity in the range from 50R to 2$\times$10$^3$R. Therapeutic application of the pulverized sample on the correct measurement of the absorbed dose in a body region of a cancer patient seems to be successful.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1051-1061
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• 1995

In order perform leak-before-break design of nuclear piping systems and integrity evaluation of reactor vessels, full stress-strain (.sigma. - .epsilon.) curves and fracture resistance (J-R) curves are required. However it is time-consuming and expensive to obtain J-R curves experimentally. The objective of this paper is to develop two methods for J-R curve prediction. In the first method, elastic-plastic finite element analyses for a series of crack length / specimen width ratio were performed. Accordingly the load versus load line displacement (P .delta.) curve corresponding to the fracture strain is obtained and the J-R curve based on the generalized locus method is obtained. In the second method, the correlation between .sigma.-.epsilon. curves and J-R curves was statistically analyzed and an empirical equation to predict the J-R curve from the .sigma.-.epsilon. test result is proposed. A good correlation between the predicted results based on the proposed methods and the experimental ones is obtained.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.21.2-21.2
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• 2011

2010년 11월 05일부터 11월 29일 중 총 12일간 진천 소재 충북대학교 천문대의 60cm 반사망원경과 ST-8 CCD 카메라를 이용하여 BD And의 BVR CCD 측광 관측을 수행하여 처음으로 BVR 광도 곡선을 완성하였다. 또한, 극심시각 결정을 위한 측광관측이 레몬산 천문대 1m 반사망원경과 충북대학교 천문대의 35cm 망원경으로 수행되었다. 우리의 관측과 SWASP 관측을 통하여 모두 31개의 극심시각을 새로이 결정하였다. 새로운 관측은 이 별의 공전주기가 이전까지 알려진 0.4629일이 아니라 그 두 배인 0.9258일이며, 기산점도 반주기 바뀌어야 함을 보여 준다. BD And의 광도요소를 Min I = HJD 2434962.8602 + 0.d9258054 E으로 새롭게 개정하였다. 이 광도요소로 작성한 우리의 BVR 광도곡선은 제1식과 제2식의 깊이가 거의 비슷하며, 식바깥 부분에 잘 발달된 파형 모양을 보인다. 이는 BD And가 짧은 주기의 RS CVn형 식쌍성임을 나타내는 것이다. 우리의 극심시각을 포함한 총 144개의 극심시각에 대한 (O-C)도를 작성한 결과, BD And의 공전주기가 규칙적으로 변화하는 것을 발견하였다. 이 변화를 보이지 않는 제3천체에 의한 광시간 효과로 가정하여, 궤도이심율이 0.78이며, 9.19년의 주기를 가진 광시간 궤도를 결정하였다.우리의 광도곡선을 2003년 Wilson-Devinney 쌍성 모형으로 분석하여 광도곡선 해를 질량비 q=1.1822, 궤도경사각 i=$86.^{\circ}16$, $T_1$=6358(K), $T_2$=6250(K), $r_1$=1.117(Rsun), $r_2$=1.321(Rsun)와 같이 산출하였다. 식바깥에서 나타나는 파형 모양의 변화는 주성의 표면에 매우 큰 흑점으로 잘 설명되며, BVR 광도곡선에서 각각 전체 광도의 각 6.4%, 8.1%, 9.9%에 해당되는 제3 광도가 검출되었다. 이는 주기연구에서 제안된 제3천체의 존재 가능성을 더 공고히 한다.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.30.1-30.1
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• 2011

2010년 11월 05일부터 11월 29일 중 총 12일간 진천 소재 충북대학교 천문대의 60cm 반사망원경과 ST-8 CCD 카메라를 이용하여 BD And의 BVR CCD 측광 관측을 수행하여 처음으로 BVR 광도 곡선을 완성하였다. 또한, 극심시각 결정을 위한 측광관측이 레몬산 천문대 1m 반사 망원경과 충북대학교 천문대의 35cm 망원경으로 수행되었다. 우리의 관측을 통하여 모두 19개의 극심시각을 새로이 결정하였다. 새로운 관측은 이 별의 공전주기가 이전까지 알려진 0.4629일이 아니라 그 두 배인 0.9258일이며, 기산점도 반주기 바뀌어야 함을 보여준다. BD And의 광도요소를 $MinI=HJD2434962.8602+0.^d9258054E$으로 새롭게 개정하였다. 이 광도요소로 작성한 우리의 BVR 광도곡선은 제1식과 제2식의 깊이가 거의 비슷하며, 식바깥 부분에 잘 발달된 파형 모양을 보인다. 이는 BD And가 짧은 주기의 RS CVn형 식쌍성임을 나타내는 것이다. 우리의 극심시각을 포함한 총 130개의 극심시각에 대한 (O-C)도를 작성한 결과, BD And의 공전주기가 규칙적으로 변화하는 것을 발견하였다. 이 변화를 보이지 않는 제3천체에 의한 광시간 효과로 가정하여, 궤도이심율이 0.78이며, 9.19년의 주기를 가진 광시간 궤도를 결정하였다. 우리의 광도곡선을 2003년 Wilson-Devinney 쌍성 모형으로 분석하여 광도곡선 해를 질량비 q=0.094, 궤도경사각 $i=85.^{\circ}4$, $T_1=6365(K)$, $T_2=6250(K)$, $R_1=1.132(Rsun)$, $R_2=1.304(Rsun)$와 같이 산출하였다. 식바깥에서 나타나는 파형 모양의 변화는 주성의 표면에 매우 큰 흑점으로 잘 설명되며, BVR 광도곡선에서 각전체 광도의 각 8.3%, 10.0%, 11.7%에 해당되는 제3 광도가 검출되었다. 이는 주기연구에서 제안된 제3천체의 존재 가능성을 더 공고히 한다.

• Journal of the Korean GEO-environmental Society
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• v.12 no.2
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• pp.23-33
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• 2011

In this paper, we got soil-water characteristic curve(SWCC) of Nak-Dong River's sand respectively as relative density 40%, 60%, 80% and content of silt 0%, 10%, 20%, 30%. As a result, the more the sand densify in the same silt content and the more the sand has silt in the same relative density, the change of volume water content was decreased. we have known effect of silt contents for SWCC and verified existing empirical formula of SWCC. As experiment results of soil-water characteristic curves compared to the empirical solutions, the results of van Genuchten(1980) and Fredlund & Xing(1994) were well-matched showing S type curves with experiment results. Especially the empirical solution of Fredlund & Xing showed almost same results of the coefficient of correlation($R^2$) equal to 0.99.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.417-426
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• 2015

The representative design elements of the road geometric structure are longitudinal slope, horizontal curve radius, super elevation, and transition curve. According to the function of a road, the design standards of these elements is applied by diverse combinations of them. This study divided expressway into homogeneous segments based on longitudinal slope and horizontal curve radius. And then, data required for analysis were matched to each segment, and the safety performance function was built by using the established data. crash modification factors which can explain traffic accident exposure rate were calculated. When the threshold value of horizontal curve radius R=1,000 m was set to 1.0, the crash modification factors at R=300 m was calculated as 1.33, which means that the accident exposure rate is increased by 33%. When the threshold value of the longitudinal slope 0% was set to 1.0, the crash modification factors demonstrated that the accident exposure rate decreases on the upward slope and the accident exposure rate increases on the downward slope. The results of this study can be used as basic information in the design of expressway geometries during the improvement or the construction of expressways.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1796-1808
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• 1997

In order to perform leak-before-break design of nuclear piping systems and integrity evaluation of reactor vessels, full stress-strain curves and fracture resistance(J-R) curves are required. However it is time-consuming and expensive to obtain J-R curves experimentally. To resolve these problems, three different methods for predicting J-R curves from tensile data were proposed by the authors previously. The objective of this paper is to develop a computer program based on those J-R curve prediction methods. The program consists of two major parts ; the main program part for the J-R curve prediction and the database part. Several case studies were performed to verify the program, and it was shown that the predicted results were, in general, in good agreement with the experimental ones.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1786-1795
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• 1997

In order to perform leak-before-break design of nuclear piping systems and integrity evaluation of reactor vessels, full stress-strain curves and fracture resistance (J-R) curves are required. However it is time-consuming and expensive to obtain J-R curves experimentally. The objective of this paper is to modify two J-R curve prediction methods previously proposed by the authors and to propose an additional J-R curve prediction method for nuclear piping materials. In the first method which is based on the elastic-plastic finite element analysis, a blunting region handling procedure is added to the existing method. In the second method which is based on the empirical equation, a revised general equation is proposed to apply to both carbon steel and stainless steel. Finally, in the third method, both full stress-strain curve and finite element analysis results are used for J-R curve prediction. A good agreement between the predicted results based on the proposed methods and the experimental ones is obtained.

• Journal of Information Technology Application
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• v.3 no.3
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• pp.91-106
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• 2001

We propose a software-reliability growth model incoporating the amount of uniform and Weibull testing efforts during the software testing phase in this paper. The time-dependent behavior of testing effort is described by uniform and Weibull curves. Assuming that the error detection rate to the amount of testing effort spent during the testing phase is proportional to the current error content, the model is formulated by a nonhomogeneous Poisson process. Using this model the method the data analysis for software reliability measurement is developed. The optimum release time is determined by considering how the initial reliability R($\chi$ 0) would be. The conditions are ($R\chi$ 0)＞$R_{o}$ , $P_{o}$ ＞R($\chi$ 0)＞ $R_{o}$ $^{d}$ and R($\chi$ 0)＜$R_{o}$ $^{d}$ for uniform testing efforts. deal case is $P_{o}$ ＞($R\chi$ 0)＞ $R_{o}$ $^{d}$ Likewise, it is ($R\chi$ 0)$\geq$$R_{o}$ , $R_{o}$ ＞($R\chi$ 0)＞R(eqation omitted) and ($R\chi$ 0)＜R(eqation omitted)for Weibull testing efforts. Ideal case is $R_{o}$ ＞ R($\chi$ 0)＞ R(eqation omitted).