• Asian Pacific Journal of Cancer Prevention
• /
• 제14권7호
• /
• pp.4121-4126
• /
• 2013

Objective: Low dose radiation may stimulate the growth and development of animals, increase life span, enhance fertility, and downgrade the incidence of tumor occurrence.The aim of this study was to investigate the antitumor effect and hormesis in an erythrocyte system induced by low-dose radiation. Methods: Kunming strain male mice were subcutaneously implanted with S180 sarcoma cells in the right inguen as an experimental in situ animal model. Six hours before implantation, the mice were given 75mGy whole body X-ray radiation. Tumor growth was observed 5 days later, and the tumor volume was calculated every other day. Fifteen days later, all mice were killed to measure the tumor weight, and to observe necrotic areas and tumor-infiltration-lymphoreticular cells (TILs). At the same time, erythrocyte immune function and the level of 2,3-diphosphoglyceric acid (2,3-DPG) were determined. Immunohistochemical staining was used to detect the expression of EPO and VEGFR of tumor tissues. Results: The mice pre-exposed to low dose radiation had a lower tumor formation rate than those without low dose radiation (P < 0.05). The tumor growth slowed down significantly in mice pre-exposed to low dose radiation; the average tumor weight in mice pre-exposed to low dose radiation was lighter too (P < 0.05). The tumor necrosis areas were larger and TILs were more in the radiation group than those of the group without radiation. The erythrocyte immune function, the level of 2,3-DPG in the low dose radiation group were higher than those of the group without radiation (P < 0.05). After irradiation the expression of EPO of tumor tissues in LDR group decreased with time. LDR-24h, LDR-48h and LDR-72h groups were all statistically significantly different from sham-irradiation group. The expression of VEGFR also decreased, and LDR-24h group was the lowest (P < 0.05). Conclusion: Low dose radiation could markedly increase the anti-tumor ability of the organism and improve the erythrocyte immune function and the ability of carrying $O_2$. Low-dose total body irradiation, within a certain period of time, can decrease the expression of hypoxia factor EPO and VEGFR, which may improve the situation of tumor hypoxia and radiosensitivity of tumor itself.

• 한국가스학회지
• /
• 제26권6호
• /
• pp.16-23
• /
• 2022

본 연구에서는 디스크와 인장시험 등을 통해 수소취성에 대한 재료 특성을 평가하고자 하였다. 이를 위해 니켈 당량이 28.5 이상인 합금 조성과, 이와 유사한 상용 합금 조성 2종에 대해 합금을 제조하였고, 각 합금은 진공유도용해로(Vacuum Induction Melting, VIM)에서 개발 합금(이하 #1)과 상용 배관(이하 각각 #2, #3)을 재용해하여 주조재로 제조하였고, 주조 합금은 단조 및 압연하여 판재로 제조하였다. 디스크형태의 시편은 0.1~1000 bar/min의 속도로 수소와 헬륨으로 가압하여 파열압력을 측정하여 수소에 대한 특성을 평가하였고, 전기화학적 방법으로 수소처리한 인장시편과 비교군에 대해 항복강도, 인장강도, 연신률, 단면적 감소율을 확인하였다. 또한 인장시편은 주사전사현미경을 통해 파단면을 확인하였다. 디스크파열시험과 수소처리 한 시편의 인장시험을 통해, 본 연구를 통해 개발된 강종의 경우 상용 강종과 비교하여 유사한 수소취성 특성을 갖고 있음을 확인하였고, 파단면 또한 미세한 두께의 벽개파괴 특성을 보였지만 기계적 강도에 큰 영향을 미치지 않음에 따라 개발된 고질소 스테인리스강은 내수소취성이 우수한 것으로 평가 할 수 있었다.

• Journal of Magnetics
• /
• 제21권1호
• /
• pp.12-19
• /
• 2016

The <100> oriented $Fe_{83}Ga_{17}$ alloys with various contents of NbC or B were prepared by directionally solidification method at the growth rate of $720mm{\cdot}h^{-1}$. With a small amount of precipitates, the columnar grains grew with cellular mode during directional solidification process, while like-dendrite mode of grains growth was observed in the alloys with higher contents of 0.5 at% due to the dragging effect of precipitates on the boundaries. The NbC precipitates disperse both inside grains and along the boundaries of $Fe_{83}Ga_{17}$ alloys with NbC addition, and the Fe2B secondary phase particles preferentially distribute along the grain boundaries in B-doped alloys. Precipitates could affect grain growth and improved the <100> orientation during directional solidification process. Small amount of precipitate element addition slightly increased the magnetostrictive strain, and a high value of 335 ppm under pre-stress of 15 MPa was achieved in the alloys with 0.1 at% NbC. Despite the fact that the effect on magnetic induction density of small amount of precipitates could be negligible, the coercivity markedly increased with addition of precipitate element for $Fe_{83}Ga_{17}$ alloy due to the retarded domain motion resulted by precipitates.

• 한국강구조학회 논문집
• /
• 제20권5호
• /
• pp.625-632
• /
• 2008

동반논문(모델개발)에서는 특별철골모멘트골조의 강접합 보-기둥 접합부의 회전능력을 예측하기 위한 해석모델을 제안하였다. 본 논문에서는 접합부 회전능력 기준으로 두 개의 극한상태를 고려하였다. 첫째, 보 단면의 국부좌굴로 인해 공칭소성강도까지 강도저하가 발생하였을 때를 회전능력으로 보는 강도저하 극한상태를 고려하였다. 둘째, 큰 진폭의 변형이 몇 번 반복 후에 좌굴된 플랜지에서 소성변형률 축적으로 야기 되는 저주기 피로 파단을 극한상태로 고려하였다. 두 극한상태까지 제안한 모델을 이용하여 단조증가하중 및 반복하중하에 일련의 해석을 수행하였다. 실무설계에서 사용되는 범위안의 다양한 H-형강 보를 모델링한 후, 플랜지 및 웨브 폭-두께비와 같은 보 단면의 기하학적 변수가 WUF-W 접합부의 회전능력과 저주기 피로수명에 미치는 영향을 관찰하였다.

• 마이크로전자및패키징학회지
• /
• 제20권4호
• /
• pp.7-11
• /
• 2013

As thermosonic ball bonding is developed for more and more advanced applications in the electronic packaging industry, the control of process stresses induced on the integrated circuits becomes more important. If Cu bonding wire is used instead of Au wire, larger ultrasonic levels are common during bonding. For advanced microchips the use of Cu based wire is risky because the ultrasonic stresses can cause chip damage. This risk needs to be managed by e.g. the use of ultrasound during the impact stage of the ball on the pad ("pre-bleed") as it can reduce the strain hardening effect, which leads to a softer deformed ball that can be bonded with less ultrasound. To find the best profiles of ultrasound during impact, a numerical model is reported for ultrasonic bonding with capillary dynamics combined with a geometrical model describing ball deformation based on volume conservation and stress balance. This leads to an efficient procedure of ball bond modelling bypassing plasticity and contact pairs. The ultrasonic force and average stress at the bond zone are extracted from the numerical experiments for a $50{\mu}m$ diameter free air ball deformed by a capillary with a hole diameter of $35{\mu}m$ at the tip, a chamfer diameter of $51{\mu}m$, a chamfer angle of $90^{\circ}$, and a face angle of $1^{\circ}$. An upper limit of the ultrasonic amplitude during impact is derived below which the ultrasonic shear stress at the interface is not higher than 120 MPa, which can be recommended for low stress bonding.

• 한국잠사곤충학회지
• /
• 제24권2호
• /
• pp.73-80
• /
• 1983

1. 인공사료육에 있어서 일본종계 현장려장품중들의 소화액 Amylase활성을 실용형질과 관련해서 조사한 결과는 다음과 같다. 가. 일본종계 현장려품종들에 있어서 소화액 Amylase활성은 품종간 차이가 있어, Hansaeng-1, Jam 115 및 Jam 117에서 강하였고 Hansang-3, Jam 113, Jam 119 및 Jam 201에서 중간이었으며, Jam 107, Jam 121 및 Gyeongchu에 있어서 약하였다. 나. 일본종계 현장려 잠품종들의 소화액 Amylase는 Daizo의 ＋(＋$^{aa}$ )형과 비교해서 아미도 -(ae)형으로 생각된다. 다. 일본중계 현장려잠품종들에 있어서 혈당량은 품종간 거의 차이가 없었으나, 성장, 견질등 실용형질에 있어서는 다소 차이가 있었다. 2. 인공사료의 a-Amylase 처리가 누에의 소화액 Amylase활성 및 실용형질에 미치는 영향을 조사한 결과는 다음과 같다. 가. a-Amylase를 처리한 사료를 먹은 누에는 처리하지 않은 누에에 비하여 성장이 다소 불량하고 소화액 Amylase활성도 약하며 성장에 대한 사료효율도 낮았다. 나. 그러나, a-Amylase를 처리한 사료를 먹은 누에는 처리하지 않은 누에에 비하여 혈당량도 많았고, 견질도 양호하였다. 따라서, 인공사료육에 있어서 사료의 a-Amylase처리는 견질에 대한 사료효율을 보다 향상시킬 수 있을 것으로 생각된다.

• Structural Engineering and Mechanics
• /
• 제68권6호
• /
• pp.747-760
• /
• 2018

In the present study, a methodology for developing fragilities of arch concrete dams to assess their performance against seismic hazards is introduced. Firstly, the probability risk and fragility curves are presented, followed by implementation and representation of the way this method is used. Amirkabir arch concrete dam was subjected to non-linear dynamic analyses. A modified three dimensional rotating smeared crack model was used to take the nonlinear behavior of mass concrete into account. The proposed model considers major characteristics of mass concrete. These characteristics are pre-softening behavior, softening initiation criteria, fracture energy conservation, suitable damping mechanism and strain rate effect. In the present analysis, complete fluid-structure interaction is included to account for appropriate fluid compressibility and absorptive reservoir boundary conditions. In this study, the Amirkabir arch concrete dam is subjected to a set of 8 three-component earthquakes each scaled to 10 increasing intensity levels. Using proposed nonlinear smeared crack model, nonlinear analysis is performed where the structure is subjected to a large set of scaled and un-scaled ground motions and the maximum responses are extracted for each one and plotted. Based on the results, fragility curves were plotted according to various and possible damages indexes. Discrete damage probabilities were calculated using statistical methods for each considered performance level and incremental nonlinear analysis. Then, fragility curves were constructed based on the lognormal distribution assumption. Two damage indexes were introduced and compared to one another. The results indicate that the dam has a proper stability under earthquake conditions at MCE level. Moreover, displacement damages index is more conservative and impractical in the fragility analysis than tensional damage index.

• 대한후두음성언어의학회지
• /
• 제33권1호
• /
• pp.31-36
• /
• 2022

Background and Objectives Proton pump inhibitors (PPIs), mucolytics, and steroids were commonly recommended after phonomicrosurgery to prevent worsening of vocal fold (VF) scar formation and subglottal swelling. However, there is no consensus about whether laryngeal reflux and thick discharge are associated with the voice outcomes following phonomicrosurgery in benign VF lesions. The purpose of this study is to examine voice outcomes of use of PPIs, mucolytics,and steroids after phonomicrosurgery. Materials and Method This randomized controlled study is performed with patients undergoing laryngomicroscopic surgery for VF polyp and cyst. Participants were randomly assigned to 1) no medication, 2) PPIs, 3) PPIs+mucolytics, and 4) PPIs+mucolytics+steroids for 2 months postoperatively. Grade, roughness, breathiness, asthenia, and strain (GRBAS) scale, stroboscopic examination, aerodynamic assessment, acoustic analysis, and Voice Handicap Index-10 (VHI-10) were performed pre- and post-operatively at 2 months. Parameters were compared among four groups. Results Among 85 patients, a total of 50 patients were included. The VHI-10, perceptual and acoustic parameters improved in all groups after surgery. However, there was no significant difference in those parameters among all groups. Conclusion PPIs, mucolytics, and steroids did not significantly influence voice outcomes after phonomicrosurgery in patients with benign VF lesions.

• Computers and Concrete
• /
• 제31권6호
• /
• pp.513-525
• /
• 2023

This research presents the experimental and theoretical evaluations on circular steel-fiber-reinforced-concrete (SFRC) columns reinforced by glass-fiber-reinforced-polymer (GFRP) rebar under the axial compressive loading. Test programs were designed to investigate and compare the effect of different parameters on the structural behavior of columns by performing tests. Theses variables included conventional concrete (CC), fiber concrete (FC), steel/GFRP longitudinal rebars, and transversal rebars configurations. A total of 16 specimens were constructed and categorized into four groups in terms of different rebar-concrete configurations, including GFRP-rebar-reinforced-CC columns (GRCC), GFRP-rebar-reinforced-FC columns (GRFC), steel-rebar-reinforced-CC columns (SRCC) and steel-rebar- reinforced-FC columns (SRFC). Experimental observations displayed that failure modes and cracking patterns of four groups of columns were similar, especially in pre-peak branches of load-deflection curves. Although the average ultimate axial load of columns with longitudinal GFRP rebars was obtained by 17.9% less than the average ultimate axial load of columns with longitudinal steel rebars, the average axial ductility index (DI) of them was gained by 10.2% higher than their counterpart columns. Adding steel fibers (SFs) into concrete led to the increases of 7.7% and 6.7% of the axial peak load and the DI of columns than their counterpart columns with CC. The volumetric ratio had greater efficiency on peak loads and DIs of columns than the type of transversal reinforcement. A simple analytical equation was proposed to predict the axial compressive capacity of columns by considering the axial involvement of longitudinal GFRP rebars, volumetric ratio, and steel spiral/hoop rebar. There was a good correlation between test results and predictions of the proposed equation.

• Nuclear Engineering and Technology
• /
• 제53권9호
• /
• pp.3068-3084
• /
• 2021

Investigations of large commercial aircraft impact effect on nuclear power plant (NPP) buildings have been drawing extensive attentions, particularly after the 9/11 event, and this paper aims to experimentally assess the damage and vibrations of NPP buildings subjected to aircraft crash. In present Part I, two shots of reduce-scaled model test of aircraft impacting on NPP building were carried out. Firstly, the 1:15 aircraft model (weighs 135 kg) and RC NPP model (weighs about 70 t) are designed and prepared. Then, based on the large rocket sled loading test platform, the aircraft models were accelerated to impact perpendicularly on the two sides of NPP model, i.e., containment and auxiliary buildings, with a velocity of about 170 m/s. The strain-time histories of rebars within the impact area and acceleration-time histories of each floor of NPP model are derived from the pre-arranged twenty-one strain gauges and twenty tri-axial accelerometers, and the whole impact processes were recorded by three high-speed cameras. The local penetration and perforation failure modes occurred respectively in the collision scenarios of containment and auxiliary buildings, and some suggestions for the NPP design are given. The maximum acceleration in the 1:15 scaled tests is 1785.73 g, and thus the corresponding maximum resultant acceleration in a prototype impact might be about 119 g, which poses a potential threat to the nuclear equipment. Furthermore, it was found that the nonlinear decrease of vibrations along the height was well reflected by the variations of both the maximum resultant vibrations and Cumulative Absolute Velocity (CAV). The present experimental work on the damage and dynamic responses of NPP structure under aircraft impact is firstly presented, which could provide a benchmark basis for further safety assessments of prototype NPP structure as well as inner systems and components against aircraft crash.