• Coupled systems mechanics
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• 제8권2호
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• pp.185-197
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• 2019

Considering the increasing use of tubular profiles in civil construction, this paper highlights the study on the behavior of welded connections between square hollow section column and I-beam, with emphasis on the assessment of the joint stiffness. Firstly, a theoretical analysis of the welded joints has been done focusing on prescriptions of the technical literature for the types of geometries mentioned. Then, a numerical analysis of the proposed joints were performed by the finite element method (FEM) with the software ANSYS 16.0. In this study, two models were evaluated for different parameters, such as the thickness of the cross section of the column and the sizes of cross section of the beams. The first model describes a connection in which one beam is connected to the column in a unique bending plane, while the second model describes a connection of two beams to the column in two bending planes. From the numerical results, the bending moment-rotation ($M-{\varphi}$) curve was plotted in order to determine the resistant bending moment and classify each connection according to its rotational capacity. Furthermore, an equation was established with the aim of estimating the rotational stiffness of welded I beam-to-RHS column connections, which can be used during the structure design. The results show that most of the connections are semi-rigid, highlighting the importance of considering the stiffness of the connections in the structure design.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1813-1824
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• 2022

This paper shows the verification work of SARAX code system in the reactor core transient calculation based on the simplified EBR-II Benchmark. The SARAX code system is an analysis package developed by Xi'an Jiaotong University and aims at the advanced reactor R&D. In this work, a neutron-photon coupled power calculation model and a spatial-dependent reactivity feedback model were introduced. To verify the models used in SARAX, the EBR-II SHRT-45R test was simplified to an ULOF transient with an input flowrate change curve by fitting from reference. With the neutron-photon coupled power calculation model, SARAX gave close results in both power fraction and peak power prediction to the reference results. The location of the hottest assembly from SARAX and reference are the same and the relative power deviation of the hottest assembly is 2.6%. As for transient analysis, compared with experimental results and other calculated results, SARAX presents coincident results both in trend and absolute value. The minimum value of core net reactivity during the transient agreed well with the reported results, which ranged from -0.3$ to -0.35$. The results verify the models in SARAX, which are correct and able to simulate the in-core transient with reliable accuracy.

• 한국진공학회지
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• 제18권2호
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• pp.108-115
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• 2009

150 주기의 InAs/GaSb (8/8-ML) 제2형 응력초격자 (SLS)를 활성층에 탑재한 초격자 적외선검출소자 (SLIP) 구조를 MBE 방법으로 성장하고, 직경 $200{\mu}m$의 개구면을 가지는 SLIP 개별소자를 시험 제작하였다 고분해능 투과전자현미경 (TEM) 이미지의 휘도분포와 X선회절 (XRD) 곡선의 위성피크의 분석 결과는 SLS 활성층은 균일한 층두께와 주기적 응력변형을 유지하는 급격한 계면의 초격자임을 입증하였다. 흑체복사 적외선 광원을 이용하여 측정한 입사파장 및 인가전압에 따른 반응도 (R)와 검출률 ($D^*$)로부터, 차단파장은 ${\sim}5{\mu}m$이고 최대 R과 $D^*$ ($\lambda=3.25{\mu}m$)는 각각 ${\sim}10^3mA/W$ (-0.6 V/13 K)와 ${\sim}10^9cm.Hz^{1/2}/W$ (0 V/13 K)임을 보였다. 반응도의 온도의존성으로부터 분석한 활성화에너지 275 meV는 광반응 과정에 개입되어 있는 가전대 및 전도대 부준위 사이의 에너지 간격 (HH1-C)과 잘 일치하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.293-296
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• 2002

In this study, the object is a development on uroflowmetry system to detect a voiding symptom conveniently in home or hospital. The hardware was composed of mechanism and system circuit part, the software was divided into firmware and PC program part. The following experiment was performed to evaluate an ability of classification and fitness. First, the following parameters was calculated in each flow curve pattern. The parameters are MFR, AFR, VOL, VT, FT, and TMF. A significant difference among parameters was examined through a statistical analysis for extracted parameters between normal and abnormal group. In the next work, the following experimentation was performed to classify the voiding symptom. Analysis of congregate rate was examined to find out classification possibility about each symptom of BPH, voiding difficulty, detrusor failure and hyperreflexia, unstable bladder. The uroflow data with the above symptom was divided into normal and abnormal group using fuzzy classifier. and that was performed appending the other group again. Fuzzy classification result using MFR and AFR was superior by 89.6 % more than grouping evaluation including VOL.

• 열처리공학회지
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• 제7권1호
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• pp.25-34
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• 1994

To investigate the effect of austenitizing tempratures on the mechanical properties and corrosion resistance of 0.19%C-13.6%Cr martensitic stainless steel, the changes in martensitic trasformation temperatures, mechanical properties and anodic polarization curve were examined after changing the austenitizing temperatures and tempering temperatures. On increasing heating rate at the same austenitizing temperatures, $A_s$, $A_r$ and $M_s$ increased. And the $M_s$ temperature showed to be decreased with increasing austenitizing temperature. With increasing tempering temperature up to $500^{\circ}C$, strength, hardness and impact value were not changed remarkably, on the other hand the tensile strength and hardness decreased and impact value increased after tempering above $550^{\circ}C$ owing to the $M_{23}C_6$ carbide precipitation. The abrupt decrease in elongation at the tempering temperture of $500^{\circ}C$ proved to the precipitation of $M_7C_3$ carbide. The effect of austenitizing temperature on the mechanical properties of the tempered specimen showed to be decreased in impact value and elongation at the austenitizing temperature of $1150^{\circ}C$. At low tempering temperatures the corrosion resistance of the tempered specimen was not changed obviously with increasing tempering temperature. On the other hand, the resistance decreased above the tempering temperature of $600^{\circ}C$ due to the precipitation of $M_{23}C_6$ carbides. The corrosion resistance showed to be improved with increasing the austenitizing temperature owing to the dissolution of carbides.

• 한국정밀공학회지
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• 제31권7호
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• pp.623-626
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• 2014

The LBB (Leak Before Break) concept is based on evaluating the fracture toughness. NUREG 1061, Vol.3 announced that the specimen for evaluating fracture resistance needs to have same thickness or thicker than pipe. Therefore, it is difficult to collect specimen from pipe which has same thickness as a pipe. So, ASTM standard suggested the use of standard specimen with 1 inch thickness. However, it has been known that an application of LBB by test results of standard specimen is conservative compare with that by real pipe. In this study, to supplement such conservatism, the evaluation of fracture resistance characteristics was performed with curved CT specimen, which has same thickness and curvature as a pipe. In addition, fracture resistance characteristics of curved CT specimen were compared with those of CT specimen. For this, shape factor F, hpl and g were obtained from FEM analysis using the limit load method.

• Journal of Magnetics
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• 제9권2호
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• pp.52-59
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• 2004

As deposited and annealed MTJs with the structure of $Ta(5 nm)/Cu(10 nm)/Ta(5 nm)/Ni_{80}Fe_{20}(2 nm)/Cu(5 nm)/ Ir_{25}Mn_{75}(10 nm)/Co_{70}Fe_{30}(2.5 nm)/Al-O/Co_{70}Fe_{30}(2.5nm)/Ni_{80}Fe_{20}(t)/Ta(5nm)/Ni_{80}Fe_{20}(t)/Ta(5 nm)$, where t=10, 30, 60 and 100 nm were characterized by XRD and magnetic hysteresis loops measurements. The XRD measurements were done in grazing incidence $(GID scan-2{\theta})$ and ${\theta}-2{\theta}$ geometry, by rocking curve $(scan-{\omega})$ and pole figures in order to establish correlation between texture and crystallites size and magnetic parameters of exchange biased and interlayer coupling. The variations of shifting and coercivity field of free and pinned layers after annealing in $300^{\circ}C$ correlate with the improvement of ［111］ texture and grains size of $Ni_{80}Fe_{20}$ and $Ir_{25}Mn_{75}$ respectively. The exchange biased and the coercivity fields of the pinned layer linearly increased with increasing grain size of $Ir_{25}Mn_{75}$, The reciprocal proportionality between interlayer coupling and coercivity fields of the free layer and grain size of $Ni_{80}Fe_{20}$ was found. The enhancement of interlayer coupling between pinned and free layers, after annealing treatment, indicates on the correlated in-phase roughness of dipolar interacting interfaces due to increase of crystallites size of $Ni_{80}Fe_{20}$.

• 한국정밀공학회지
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• 제31권6호
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• pp.551-557
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• 2014

Ideally, it is preferable to obtain the fracture characteristics of a piping from the fracture toughness of real pipes. However, a fracture toughness test on real pipes not only incurs much expense, but is very difficult to perform. Therefore fracture toughness tests have been carried out with standard specimens instead of real pipes. But, the estimates of fracture toughness obtained from standard specimens are more conservative than those of real pipes owing to the difference in the constraint effect between real pipes and standard specimens. Therefore, we have been studied with equivalent stress gradient specimen (ESG) which is designed to behave equally compared to real pipe about stress gradient on crack tip. In this study, we will evaluate fracture characteristics of equivalent stress gradient specimen by using analytical methods and compare with those of real pipe. And finally investigate suitability of equivalent stress gradient specimen.

• Animal Bioscience
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• 제36권4호
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• pp.584-590
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• 2023

Objective: This research aimed to explore the changes in the observed abdominal sagging index (ASI) and reproductive performance of Roman male and female geese during the breeding period. Methods: The 339 six-month-old breeding geese (109 male; 230 female) were used in this study, in which five male and five female geese were slaughtered on a monthly basis to record the ASI. Results: The short diameter of the testes of the male goose when the female goose lays eggs and in the second, third, and fourth months was significantly wider than in the fifth months (19.0, 20.8, 21.4, and 19.6 vs 12.7 and 14.0 mm/bird; p = 0.0105). On the other hand, the testicular weight of the male goose in the second and third months after the female goose lays eggs was significantly higher than that in the second and fifth months after laying (0.33% and 0.37% vs 0.11% and 0.19%; p = 0.0212). During the exploring period, the length and weight of the fallopian tube, the weight of the ovary, the number of follicles in 2 to 3 cm, the number of follicles in 3 to 4 cm, the fallopian tube weight in the carcass weight percentage, and the ovary weight in the carcass weight percentage all demonstrated a significant curve response. Further, female ASI was positively correlated with reproductive tract length (r = 0.815; p<0.05) and egg production per female (r = 0.790; p<0.05). Conclusion: The ASI classification method is more objective and easy to distinguish. This scoring method has a high correlation with the number of eggs laid by each goose and the length of the reproductive tract, inferring that the goose observation could take advantage of ASI during egg-laying and can predict the reproductive system development during the laying period and determine when the breeding goose begins to lay eggs.

• 한국화재소방학회논문지
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• 제34권1호
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• pp.18-25
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• 2020

본 연구에서는 보온재의 설치 상태를 고려한 ISO 20632와 NFPA 274 시험 기준에 따른 발열량 산출 결과를 분석하였다. 이를 위해서 보온재 총 6종(은박 발포폴리에틸렌(PE(S)), 무은박 발포폴리에틸렌폼(PE(N)), 고무발포(Rubber), 일본-폴리에틸렌폼(PE(J)), 일본-폴리우레탄폼(PU(J)) 그리고 일본-스티로폼(ST(J)))에 대해서 EN 13501-1과 화재성장곡선에 따른 난연 등급을 구분하였다. 그 결과 PU(J), PE(J) 그리고 PE(N)는 Class E 및 Ultra-fast, NFPA 274 시험기준에 의한 PE(S)는 Class D 및 Fast, ISO 20632에 의한 PE(S)는 Class C 및 Slow, 그리고 Rubber와 ST(J)는 Class B 및 Slow로 나타났다. 하지만, 난연 등급 평가 기준인 최대 발열량에 대한 시간평균 기울기는 시험 방법에 따라서 동일 보온재에 대하여 다르게 나타났으며, 보다 정확한 원인을 분석하기 위한 기초 연구가 필요한 것으로 판단된다.