• Biomolecules & Therapeutics
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• 제29권4호
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• pp.434-444
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• 2021

BRAF inhibitors are insufficient monotherapies for BRAF-mutated cancer; therefore, we investigated which inhibitory pathway would yield the most effective therapeutic approach when targeted in combination with BRAF inhibition. The oncogenic BRAF inhibitor, PLX4720, increased basal autophagic flux in BRAF-mutated cells compared to wild-type (WT) BRAF cells. Interestingly, early autophagy inhibition improved the effectiveness of PLX4720 regardless of BRAF mutation, whereas late autophagy inhibition did not. Although ATG5 knockout led to PLX4720 resistance in both WT and BRAF-mutated cells, the MEK inhibitor trametinib exhibited a synergistic effect on PLX4720 sensitivity in WT BRAF cells but not in BRAF-mutated cells. Conversely, the prolonged inhibition of endoplasmic reticulum (ER) stress reduced basal autophagy in BRAF-mutated cells, thereby increasing PLX4720 sensitivity. Taken together, our results suggest that the combined inhibition of ER stress and BRAF may simultaneously suppress both pro-survival ER stress and autophagy, and may therefore be suitable for treatment of BRAF-mutated tumors whose autophagy is increased by chronic ER stress. Similarly, for WT BRAF tumors, therapies targeting MEK signaling may be a more effective treatment strategy. Together, this study presents a rational combination treatment strategy to improve the efficacy of BRAF inhibitors depending on BRAF mutation status.

• Nuclear Engineering and Technology
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• 제30권6호
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• pp.555-567
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• 1998

Alloy 600 and 690 steam generator tubes fabricated in Korea were evaluated by flare tests according to ASTM standards. The stress acting in the tube elements during the tests was predicted. All the tubes, including alleys 600 and 690, satisfied the requirement of a 30% or 35% O.D expansion. Flow curves obtained from the flare test were found to be higher in alloy 690 tubes than in alloy 600 ones. The difference between alloy 600 and 690 tubes increased gradually with flaring percentage (F.P,%). An effective stress corresponding to mean yield stress was introduced and calculated. It showed that the prediction values were in good agreement with the measured ones for all the 690 and 600 alloy tubes. It became possible to predict the amount of acting stresses within tubes during expansion process.

• 한국환경과학회지
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• 제33권5호
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• pp.333-343
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• 2024

This study aimed to investigate whether inhaling the aroma of essential oils could alleviate physiological stress responses and mimic the effects of forest therapy in urban settings. Briefly, 31 participants underwent stress index assessments for two days and inhaled the selected plant essential oils. The effects of this treatment on physiological responses were determined through electroencephalogram (EEG) and heart rate variability (HRV) measurements taken before and after inhaling the aroma of essential oils, extracting results for low frequency (LF) and high frequency (HF) components of HRV, as well as 𝜃 and 𝛼 brainwave activities. The results indicated that lavender oil did not yield significant differences, whereas pine, chamomile, and cypress oils exhibited significant differences in effects. Overall, stress relief was associated with enhanced 𝜃 and 𝛼 brainwave activities, a decrease in the LF component and an increase in the HF component of HRV. Among the essential oils studied, pine oil was the most effective. These findings underscore the potential of plant essential oils in replicating the therapeutic benefits of forest therapy, even in urban environments. Further investigations into their utilization are warranted to better understand and harness their therapeutic potential.

• 유변학
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• 제11권2호
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• pp.82-90
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• 1999

전기유변 유체(electorheological fluid)는 전기장이 가해지면 아주 짧은 시간에 유변 물성이 급격히 변하며 그 응답이 반복적으로 수행될 수 있는 유체이다. 전기유변 유체는 전기장의 세기에 따라 면찰 응력(shear stress)과 점도의 크기를 조절할 수 있고, 짧은 응답시간은 빠른 제어를 요하는 분야에 효과적으로 이용될 수 있지만, 낮은 항복 응력, 조업 온도 범위의 제한성, 전력 소비에 의한 열적 불안정성, 그 외에도 응집, 침전 등의 단점이 있다. 특히, 이 유체가 갖는 항복 응력의 크기와 그 성질은 실제 장치에 응용하는데 중요한 특성이다. 이러한 문제점을 해결하기 위해 면찰 유동(shear flow)이 아닌 압착 유동(squeezing flow)을 고려하게 되었고, 이 유동 하에서의 전기유변 유체의 거동을 이해하기 위해 본 연구에서는 전기유변 유체의 압착 유동에 대한 동적 수치모사를 수행하였다. 고립된 사슬 구조에 대한 수치모사를 통하여 사슬의 위치와 압착 속도를 변화 시키면서 이에 따른 수력학적 힘과 정전기적 힘의 효과를 예측하였으며, 이를 토대로 많은 사슬을 포함한 현탁액 모델에 대한 수치모사를 수행하였다. 그 결과 실험에서 관찰할 수 있는 수직 응력의 증가와 초기 항복 응력의 존재를 확인하였고, 수직 응력의 효과적인 제어는 수력학적 힘과 정전기적 힘 간의 최적화된 조건에서 얻어질 수 있음을 예측하였다. 이러한 수치모사의 개발을 통해 압착 유동을 이용한 전기유변 유체의 응용에 대한 이론적인 토대를 마련하였고, 향후 보다 깊은 이해를 위한 기반을 구축할 수 있었다.

• 농업과학연구
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• 제50권4호
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• pp.883-902
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• 2023

Water is critical to the health and productivity of fruit trees. Efficient monitoring of water stress is essential for optimizing irrigation practices and ensuring sustainable fruit production. Short-range sensing can be reliable, rapid, inexpensive, and used for applications based on well-developed and validated algorithms. This paper reviews the recent advancement in fruit tree water stress detection via short-range sensing, which can be used for irrigation scheduling in orchards. Thermal imagery, near-infrared, and shortwave infrared methods are widely used for crop water stress detection. This review also presents research demonstrating the efficacy of short-range sensing in detecting water stress indicators in different fruit tree species. These indicators include changes in leaf temperature, stomatal conductance, chlorophyll content, and canopy reflectance. Short-range sensing enables precision irrigation strategies by utilizing real-time data to customize water applications for individual fruit trees or specific orchard areas. This approach leads to benefits, such as water conservation, optimized resource utilization, and improved fruit quality and yield. Short-range sensing shows great promise for potentially changing water stress monitoring in fruit trees. It could become a useful tool for effective fruit tree water stress management through continued research and development.

• Earthquakes and Structures
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• 제18권2호
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• pp.215-222
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• 2020

In this paper, slit steel rubber bearing is presented as an innovative seismic isolator device. In this type of isolator, slit steel damper is an energy dissipation device. Its advantages in comparison with that of the lead rubber bearing are its simplicity in manufacturing process and replacement of its yielding parts. Also, slit steel rubber bearing has the same ability to dissipate energy with smaller value of displacement. Using finite element method in ABAQUS software, a parametric study is done on the performance of this bearing. Three different kinds of isolator with three different values of strut width, 9, 12 and 15 mm, three values of thickness, 4, 6 and 8 mm and two steel types with different yield stress are assessed. Effects of these parameters on the performance characteristics of slit steel rubber bearing are studied. It is shown that by decreasing the thickness and strut width and by selecting the material with lower yield stress, values of effective stiffness, energy dissipation capacity and lateral force in the isolator reduce but equivalent viscous damping is not affected significantly. Thus, by choosing appropriate values for thickness, strut width and slit steel damper yield stress, an isolator with the desired behavior can be achieved. Finally, the performance of an 8-storey frame with the proposed isolator is compared with the same frame equipped with LRB. Results show that SSRB is successful in base shear reduction of structure in a different way from LRB.

• International Journal of Precision Engineering and Manufacturing
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• 제5권2호
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• pp.32-38
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• 2004

The electrorheological(ER) fluid has been used to the ultraprecision polishing of single crystal silicon as new polishing slurry whose properties such as yield stress and particle structure changed with the application of an electric field. In this work, it is aimed to find the effective parameters in the ER fluid on material removal in the polishing system whose structure is similar to that of the simple hydrodynamic bearing. The generated pressure in the gap between a moving wall and a workpiece, as well as the electric field-induced stress of the mixture of ER fluid-abrasives, is evaluated experimentally, and their influence on the polishing of single crystal silicon is analyzed. Moreover, the behavior of abrasive and ER particles is described.

• 한국안전학회지
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• 제10권3호
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• pp.3-10
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• 1995

For most engineering materials are influenced by the dominant mechanism resisting crack extention under large scale yielding conditions. Continuum mechanics analysis shows that fracture toughness, in addition to depending on young's modulus, flow stress strain hardening exponent, and yield strain, should be nearly proportoinal to the effective fracture ductility obtained for the stress state characteristic for region ahead of the crack; plane stress or plane strain. It's known that, in most ductile materials, crack propagation of the material strongly governed by the $J_{IC}$ value, which is still difficult to determine for it's complicate and treble-some determinative process. This paper, on the assumption that, initiation of crack tip strain field reaches on the relationships between the critical value of J-integral ($J_{IC}$) and the local fracture strain(${\varepsilon}_c$) in uniaxial tensile test in the region of maximun reduction areas was described.

• Computers and Concrete
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• 제3권1호
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• pp.43-64
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• 2006

A tendon model that can effectively be used in finite element analyses of prestressed concrete (PSC) structures with bonded tendons is proposed on the basis of the bond characteristics between a tendon and its surrounding concrete. Since tensile forces between adjacent cracks are transmitted from a tendon to concrete by bond forces, the constitutive law of a bonded tendon stiffened by grouting is different from that of a bare tendon. Accordingly, the apparent yield stress of an embedded tendon is determined from the bond-slip relationship. The definition of the multi-linear average stress-strain relationship is then obtained through a linear interpolation of the stress difference at the post-yielding stage. Unlike in the case of a bonded tendon, on the other hand, a stress increase beyond the effective prestress in an unbonded tendon is not section-dependent but member-dependent. The tendon stress unequivocally represents a uniform distribution along the length when the friction loss is excluded. Thus, using a strain reduction factor, the modified stress-strain curve of an unbonded tendon is derived by successive iterations. The validity of the proposed two tendon models is verified through correlation studies between analytical and experimental results for PSC beams and slabs.

• 한국지반공학회논문집
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• 제22권4호
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• pp.85-94
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• 2006

본 논문에서는 고결(Cementation)에 의한 모래의 비배수 거동변화를 파악하기 위하여 석고를 고결유발제로 사용한 시료를 조성한 후 등방삼축시험(CIU)을 실시하였으며, 상대밀도 및 고결정도에 따른 거동 양상을 분석하였다. 연구결과 모래의 고결은 항복강도$(q_y)$, 항복시 할선탄성계수$(E_y)$, 첨두마찰각$(\Phi_p)$의 상당한 증가를 유발시키고, 상대밀도보다 모래의 거동에 더 큰 영향을 끼치는 것으로 확인되었다. 그러나 고결결합이 파괴된 이후, 모래의 거동은 고결보다는 상대밀도의 영향을 더 크게 받는 것으로 나타났다. 또한 고결결합에 의한 압축성 감소는 간극수압 발생율을 감소시켜 고결모래의 유효응력 경로가 미고결 모래의 전응력 경로쪽으로 편향되어 발생하였다. 고결결합이 파괴되기 전에는 다일레이션 경향이 감소하지만, 결합이 파괴된 후에는 미고결 모래보다 더 큰 다일레이션 경향이 유발되었다.