• 한국의류학회지
• /
• 제28권3_4호
• /
• pp.414-421
• /
• 2004

To reduce farmer's stress from solar radiation and ultraviolet radiation(UV), the sunshade hat with a large brim and special structure for ventilation was developed and tested with manikin heads outdoors at previous study(Kim and Choi, 2002). To evaluate the protection efficiency of the sunshade hat, human trial test was performed at outdoors. The results were as follows; Skin temperatures(7 sites), heart rate, temperature inside the hats, temperature and relative humidity inside clothing on the back in wearing developed sunshade hat were significantly lower than those in wearing the controlled hat. In subjective sensation, subjects answered to feel significantly hotter, more humid and more uncomfortable in wearing the controlled hat. But relative humidity inside the hats was significantly higher in wearing developed hat. In rectal temperature, there were no significant differences between two hats.

• Journal of applied mathematics & informatics
• /
• 제41권5호
• /
• pp.1085-1102
• /
• 2023

In this study the magneto hydrodynamic (MHD) micro polar fluid flow of a viscous incompressible fluid past a porous medium in the presence of chemical reaction is considered. This work is devoted to investigate the Soret effect and Electromagnetic radiation effect and analyze analytically. In the energy equation the applied magnetic field strength and in the concentration equation the Soret effect are incorporated. The basic PDE (partial differential equations) are reduced to ODE (ordinary differential equations) using non dimensional variables. Then the analytical solution of the dimensionless equations are found using perturbation technique. The features of the fluid flow parameters are analyzed, discussed and explained graphically. The graphical solutions are found using MATLAB R2019b. Skin friction coefficient at the wall, Couple stress coefficient at the plate and the local surface heat flux are also thoroughly examined. Overall, this study sheds light on the complex interplay between physical parameters in the behavior of MHD micro-polar fluid past a porous medium in the presence of chemical reaction.

• Journal of Welding and Joining
• /
• 제20권2호
• /
• pp.50-58
• /
• 2002

Residual stress is generated in the structures as a result of irregular elastic-plastic deformation during fabrication processes such as welding, heat treatment, and mechanical processing. There are several factors attributed to the origin of residual stresses, tensile or compressive. The stresses can be determined by destructive ways or nondestructive ways using X-ray or neutron diffraction. Although X-ray diffraction is a well established technique, it is practically limited to near-surface stresses. Neutrons penetrate easily into most materials and neutron diffraction permits non-destructive evaluation of lattice strain within the bulk of large specimens because the radiation is more deeply penetrating for metallic engineering components. This paper presented application of neutron diffraction technique to the residual stress measurement using 20 mm thick welded stainless steel plate($100{\times}100 \textrm{mm}^2$)

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.617-620
• /
• 1997

In this paper, the thermal stress analysis of spent nuclear fuel disposal canister in a deep repository at 500m underground is done for the underground pressure variation. Since the nuclear fuel disposal usually emits much heat and radiation, its careful treatment is required. And so a long term safe repository at a deep bedrock is used. Under this situation, the canister experiences some mechanical external loads such as hydrostatic pressure of underground water, swelling pressure of bentonite buffer, and the thermal load due to the heat generation of spent nuclear fuel in the basket etc.. Hence, the canister should be designed to designed to withstand these loads. In this paper, the thermal stress analysis is done using the finite element analysis code, NISA.

• 한국농공학회지
• /
• 제43권6호
• /
• pp.103-112
• /
• 2001

The development of infrared thermometry has led many researchers to use plant temperatures, and specifically the temperature of the crop canopy in the field, for estimating the water stress of a crop. The purpose of this study was to evaluate the role of leaf temperature in irrigation scheduling. An experiment was carried out in a greenhouse with chinese cabbage. Leaf temperature was measured with infrared thermometry and evapotranspiration of the crop was measured by lysimeters. Influence of the difference between leaf temperature and air temperature on crop evapotranspiration was evaluated under varying water stress condition. A further objective was to evaluate the effect of other climatic variables on the relationship between evapotranspiration and temperature difference between leaf and air. A statistical model for estimating evapotranspiration using the temperature difference, relative humidity. and radiation was developed and tested. Crop water stress index was calculated using vapour pressure deficit and the temperature difference. Relations between the crop water stress index and crop evapotranspiration was tested. The index was closely related with evapotranspiration.

• 생명과학회지
• /
• 제27권6호
• /
• pp.708-725
• /
• 2017

전리방사선은 물질과 상호작용하여 원자내의 중성자나 양성자, 궤도전자를 충분히 제거시킬 수 있는 에너지이다. 이와 같은 전리방사선은 DNA이나 세포질 소기관과 세포질의 방사선 분해 생성물을 통해 직접적, 간접적으로 상호작용하여 분자구조를 변화시키는 산화적 대사를 일으킨다. 이러한 전리 현상은 분자수준에서 조직을 손상시키고, 세포 기능을 파괴할 수 있다. 따라서, 전리방사선에 의해 유도된 이온채널과 수송 변형이 보고되고 있다. 이러한 현상이 항상성을 유지하기 위한 생화학적 과정을 무너뜨리면, 유도된 생물학적 변화가 지속되고 후대로 영향을 미친다. 또한, 전리방사선의 영향으로 형성된 활성산소는 세포연접을 통해 인접세포로 퍼져 나갈 수 있다. 방사선량, 선량률, 선질에 따라 이러한 메커니즘이 충분히 방어할 수도 있고 그렇지 않을 수도 있다. 본 총설에서는 방사선생물학의 개념을 뒷받침하는 전리방사선의 세포수준에서 생물학적 효과에 대한 보고서를 간략히 알아보았다. 전리방사선의 생물학적 효과를 잘 이해하면 방사선을 잘 이용할 수 있고, 방사선피폭으로부터 더 나은 방호를 할 수 있을 것이다.

• 한국식품영양학회지
• /
• 제31권4호
• /
• pp.495-501
• /
• 2018

Ultraviolet B (UVB) exposure is a risk factor for skin damage resulting in oxidative stress, inflammation, and cell death. The purpose of this study was to investigate the physicochemical properties of Platycodon grandiflorum (PG) to improve its biological activities using a three-step steaming process. We investigated the protective effects of PG and steamed PG extracts on human dermal fibroblasts (HDFs) against UVB radiation-induced oxidative stress and inflammation as well as the underlying mechanisms. The antioxidant potential of the PG extracts was evaluated by measuring the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) scavenging activity. ABTS and DPPH were shown by the 0, 30, and 70% ethanol extracts of 2S-PG and 3S-PG ($IC_{50}$, 28~45 and $27{\sim}30{\mu}g/mL$, respectively). Treatment of UVB-irradiated cells with steamed PG ($25{\sim}400{\mu}g/mL$) did not affect their viability. The streamed PG extract suppressed UVB-induced generation of reactive oxygen species (ROS). In addition, streamed PG extract reduced cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) protein expression in UVB-irradiated HDF, regulating nuclear factor $(NF)-{\kappa}B$ expression. These findings suggest that steamed PG extract may be potentially effective against inflammation associated with UVB-induced oxidation stress.

• 한국지진공학회논문집
• /
• 제24권6호
• /
• pp.253-266
• /
• 2020

The extended slip-weakening model was investigated by using a compiled set of source-spectrum-related parameters, i.e. seismic moment M_o, S-wave velocity V_s, corner-frequency f_c, and source-controlled high-cut frequency fmax, for 113 shallow crustal earthquakes (focal depth less than 25 km, M_W 3.0~7.5) that occurred in Japan from 1987 to 2016. The investigation was focused on the characteristics of stress drop, radiation energy-to-seismic moment ratio, radiation efficiency, and fracture energy release rate, G_c. The scaling relationships of those source parameters were also investigated and compared with those in previous studies, which were based on generally used singular models with the dimensionless numbers corresponding to f_c given by Brune and Madariaga. The results showed that the stress drop from the singular model with Madariaga's dimensionless number was equivalent to the breakdown stress drop, as well as Brune's effective stress, rather than to static stress drop as has been usually assumed. The scale dependence of stress drop showed a different tendency in accordance with the size category of the earthquakes, which may be divided into small-moderate earthquakes and moderate-large earthquakes by comparing to M_o = 10¹⁷~10¹⁸ Nm. The scale dependence was quite similar to that shown by Kanamori and Rivera. The scale dependence was not because of a poor dynamic range of recorded signals or missing data as asserted by Ide and Beroza, but rather it was because of the scale dependent V_r-induced local similarity of spectrum as shown in a previous study by the authors. The energy release rate G_c with respect to breakdown distance D_c from the extended slip-weakening model coincided with that given by Ellsworth and Beroza in a study on the rupture nucleation phase; and the empirical relationship given by Abercrombie and Rice can represent the results from the extended slip-weakening model, the results from laboratory stick-slip experiments by Ohnaka, and the results given by Ellsworth and Beroza simultaneously. Also the energy flux into the breakdown zone was well correlated with the breakdown stress drop, ${\tilde{e}}$ and peak slip velocity of the fault faces. Consequently, the investigation results indicate the appropriateness of the extended slip-weakening model.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권16호
• /
• pp.7103-7110
• /
• 2015

The present study was conducted to investigate the effect of ${\gamma}$-radiation alone or combined with a cytotoxic drug, simvastatin, on viability and cell cycling of a myeloma cell line. P3NS1 myeloma cells were treated with the selected dose of simvastatin ($0.1{\mu}M/l$) 24 hours prior to ${\gamma}$-irradiation (0.25, 0.5 and 1Gy). The cell viability, induction of apoptosis, cell death, cell cycling, generation of ROS, and expression of P53, Bax, Bcl2, caspase3, PARP1 and Fas genes were estimated. The results indicated that simvastatin ($0.1{\mu}M/l$) treatment for 24 hours prior to ${\gamma}$-irradiation increased cell death to 37.5% as compared to 4.81% by radiation (0.5Gy) alone. It was found that simvastatin treatment before irradiation caused arrest of cells in G0/G1 and G2/M phases as assessed using flow cytometry. Interestingly, simvastatin treatment of P3NS1 cells increased the intracellular ROS production and decreased antioxidant enzyme activity with increased P53, Bax and Caspase3 gene expression while that of Bcl2 was decreased. Consequently, our results indicated that pre-treatment with simvastatin increased radio sensitivity of myeloma tumor cells in addition to apoptotic effects through an intrinsic mitochondrial pathway.

• Radiation Oncology Journal
• /
• 제27권1호
• /
• pp.1-9
• /
• 2009

방사선치료후 발생할 수 있는 골 손상은 골반 부전골절, 방사선 골 괴사, 무혈성 괴사, 골 육종 등이다, 특히 최근 방사선치료후의 골탄성도의 변화로 발생하는 골반 부전골절에 관하여 많은 보고가 있었다. 과거 방사선치료 후의 골 손상 특히 골절의 빈도는 선형가속기를 이용한 메가볼트 방사선치료 바뀌면서 현저히 줄어 들어서 매우 낮은 것으로 보고 되었으나 최근에는 $8{\sim}20%$로 보고가 되고 있다. 따라서 골반 부전골절의 임상적 의미와 중요성과 예방 및 치료에 대하여 관심이 증가되고 있다. 저자는 자궁경부암 치료 후 관찰한 골반 부전골절, 골 괴사, 무혈성 괴사, 및 2차성 골육종등 골반골 변화와 손상에 관하여 저자의 경험과 문헌고찰을 통하여 보고 하고자 한다.