The influence of specimen geometry and notch on the hydrogen embrittlement of an SA372 steel for pressure vessels was investigated in this study. A slow strain-rate tensile (SSRT) test after the electrochemical hydrogen charging method was conducted on four types of tensile specimens with different directions, shapes (plate, round), and notches. The plate-type specimen showed a significant decrease in hydrogen embrittlement resistance owing to its large surface-to-volume ratio, compared to the round-type specimen. It is well established that most of the hydrogen distributes over the specimen surface when it is electrochemically charged. For the round-type specimens, the notched specimen showed increased hydrogen susceptibility compared with the unnotched one. A notch causes stress concentration and thus generates lots of dislocations in the locally deformed regions during the SSRT test. The solute hydrogen weakens the interactions between these dislocations by promoting the shielding effect of stress fields, which is called hydrogen-enhanced localized plasticity mechanisms. These results provide crucial insights into the relationship between specimen geometry and hydrogen embrittlement resistance.

In this study, the experiments and analyses were carried out in order to investigate the fracture characteristics on the adhesive at the specimen bonded with aluminum and aluminum-foam. The same conditions were given for the experiments and analyses. The results are investigated by the graph of reaction force according to displacement. It was found that the experimental and the analytical data were very similar to each other. On the basis of the data, the reliability of the analysis data could be confirmed. The notches were produced at the distances of 40, 110, 150, and 190 mm from the front of the test specimen, and the maximum reaction force was compared accordingly. It was found that the highest reaction force was generated at the front end of the adhesive and the lowest reaction force was found at the middle of the adhesive interface. Finally, when the equivalent stress in the test specimen was examined, it was found that the highest stress was obtained at the distance of 110 mm. It can be deduced. As the notch formation point are similar to the point when stress is dispersed as the adhesive is peeled off, it is possible to infer the high stress compared to other test specimens.

In this study, we investigated the properties of adhesive materials with different lightweight materials such as CFRP and Al-foam. The specimens were tested and analyzed using DCB (Double Cantilever Beam) specimens. In order to secure the reliability of the finite element method, the test and analysis were carried out, and the reliability of the finite element method was secured by using the graph of reaction force to displacement based on the experiment and analysis. The study on the adhesive failure characteristics according to the position of notch hole proceeded. Notch holes were generated at the locations of 40, 110, 150 and 190 mm from the beginning of the specimen near the bonding interface, and the analysis conditions used were the same as those used for securing reliability. The obtained study results are compared with reaction force and equivalent stress. In the case of reaction force, the overall tendency is similar but the difference in maximum reaction force is found. It was found that higher reaction forces appeared at the beginning than at the end of the bonding interface. When the equivalent stresses in the specimens were examined, the value of CFRP was seen to be 30 times higher as much as that of Al-foam.

To control the flow of fluid, several kinds of valves are used. Especially, Main Control Valve (MCV) is the key element of hydraulic system which performs complex control not only controlling the flow of fluid, but also prevent damage of equipment by supplying proper hydraulic pressure to actuator and draining over-supplied hydraulic pressure. While general control valves are producing in domestically, entire quantity of main control valves are depended on importation and it depreciates competitiveness in cost, and time. In this study, to derive the best design of notch structure by following the orifice flow of 6-linked main control valve and the relation between “notch structure” which is the most fundamental element to control the velocity of the fluid and “pressure distribution”, the flow characteristic is compared by comprehending hydraulic pressure and velocity of the fluid using CFD simulation when spool valve is used for “meter-in” and “meter-out” through the opening of the notch structure.

The hydraulic equipments has a high utilization in the many works such as the excavation, planation and crane works in the construction sites. They are an essential equipments in the construction site and the loading & unloading works of the large size objects. In the many parts which are composed of the hydraulic equipments, the main control valve(MCV) is the core of the equipments. The hydraulic energy from the pump controls the direction and the rate of flow by MCV. And the flow rate of the MCV inlet operate some actuators to perform the diverse action of the spool. So, it is important to analysis the shape of the flow path and the notch of the spool. In order to perform the optimal design of the 6-way valve, the study for the analysis of the flow path and the pressure distribution according to the pressure control, which to meet use condition, must be performed. In this study, we carried out the reverse-engineering of the MCV using the parametric technique as the first step in the research of the MCV. And we analyzed the shape of the flow path and the pressure distribution for the notch of the spool using the optimal modeling of the MCV.

The Notch signaling pathway regulates cell proliferation, apoptosis and cell fate decision. Recent preclinical and clinical evidence supports a pro-oncogenic function for Notch signaling in several solid tumors including breast and prostate cancer. Consequently, there is increasing interest in targeting Notch signaling therapeutically in cancer patients. Notch inhibitors, particularly gamma-secretase inhibitors, are being investigated as candidate cancer therapeutic agents. However, rational targeting of Notch signaling in cancer will require a systematic exploration of several areas that remain incompletely understood. Therefore, a clear understanding of the Notch signaling and its cross-talk with other signaling cascade will increase our ability to design rational combination regimens for cancer therapy.

Major characteristics of embryonic stem cells (ESCs) are sustaining of stemness and pluripotency by self-renewal. In this report, transcriptional profiles of the molecules in the developmentally important signaling pathways including Wnt, BMP4, TGF-β, RTK, Hh, Notch, and JAK/STAT signaling pathways were investigated to understand the self- renewal of mouse ESCs (mESCs), J1 line, and compared with the NIH3T3 cell line and mouse embryonic fibroblast (MEF) cells as controls. In the Wnt signaling pathway, the expression of Wnt3 was seen widely in mESCs, suggesting that the ligand may be an important regulator for self-renewal in mESCs. In the Hh signaling pathway, the expression of Gli and N-myc were observed extensively in mESCs, whereas the expression levels of in a Shh was low, suggesting that intracellular molecules may be essential for the self-renewal of mESCs. IGF-I, IGF-II, IGF-IR and IGF-IIR of RTK signaling showed a lower expression in mESCs, these molecules related to embryo development may be restrained in mESCs. The expression levels of the Delta and HES5 in Notch signaling were enriched in mESCs. The expression of the molecules related to BMP and JAK-STAT signaling pathways were similar or at a slightly lower level in mESCs compared to those in MEF and NIH3T3 cells. It is suggested that the observed differences in gene expression profiles among the signaling pathways may contribute to the self-renewal and differentiation of mESCs in a signaling-specific manner.

샤피 V-노치 충격 하중-변위 곡선으로부터 얻은 균열정지하중을 이용하여 원자로압력용기강의 균열정지파괴인성(KIa)을 예측할 수 있는 방법을 모색하고 그 타당성을 고찰하였다. 샤피충격 하중-변위 곡선으로부터 얻은 균열정지하중값의 변화는 특성온도로 보정된 지수함수의 형태로 잘 표현될 수 있었다. 특성온도 TPa=2kN은 실험적인 무연성천이온도(TNDT) 및 T41 J과 높은 상관성을 나타냈으며, 원자로압력용기강의 균열정지파괴인성을 표현하는 새로운 특성온도로 사용할 수 있을 것으로 판단되었다. 또한 균열정지하중값의 변화는 파면으로부터 측정된 안정균열길이의 변화와 매우 높은 상관성을 나타내었다. 따라서 무딘 노치를 갖는 시편에 대한 계장화샤피충격시험을 통하여 균열정지하중 및 안정균열길이를 측정하믈써 비교적 정확하게 원자로압력용기강에 대한 하한값의 파괴인성치(KIa)를 평가하는 것이 가능한 것으로 판단되었다.

Concrete structure is a construction material with durability and cost-benefit, however the corrosion in embedded steel causes a critical problem in structural safety. This paper presents an evaluation of chloride resistance and pull-off performance with various corrosion level. For the work, OPC(Ordinary Portland Cement) concrete and GGBFS(Ground Granulated Blast Furnace Slag) concrete are prepared with normal steel. Artificially notch induced FRP Hybrid Bar is also prepared and embedded in OPC concrete and accelerated corrosion test is performed. Through the test, FRP Hybrid Bar with notch is evaluated to have insignificant effect on pull-off capacity when corroded steel shows only 21% level of pull-off capacity. Furthermore GGBFS concrete with normal steel shows over 70% level of pull-off capacity due to reduced corrosion currency.