• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.1530-1535
• /
• 2011

Heat radiation of LED luminaires has risen a problem when applied indoor. LEDs can save energy with higher efficacy than other light sources. However, their heat radiation may increase power consumption for air-conditioning. Therefore, this paper carried out a comparative analysis on the amount of heat radiation for MR16, E26 bulb, and down-light which will be replaced to LED luminaires. Heat amount of LED-MR16 and LED-downlight was 48% and 87.5% lower than that of conventional lamps, halogen MR16 and E26 CFL, respectively. Consequently, the heat amount and indoor temperature were proportional to the power consumption of luminaire. Therefore, the use of LED luminaire can reduce the amount of heat radiation as well as power consumption.

• Journal of Advanced Marine Engineering and Technology
• /
• 제25권1호
• /
• pp.146-154
• /
• 2001

In almost all real situations, there will be a radiant interchange between adjacent fins with the base surface as well as with the external environment. In the problem of this study, a rectangular fin is attached to a based. Our concern is whether the convective fin efficiency can be increased by the radiation heat exchanged between the fin and the base surface and how much. If the fin temperature toward the tip increased by the effect of radiation, the convective heat transfer increase due to the temperature difference between the ambient temperature and the surface temperature of the fin. If this true, the efficiency of the fin due to the radiation will increase. Attention is directed toward several parameters which have major roles on getting values of the fin efficiencies in several different values of parameters. Many different cases are, therefore, to be examined to have maximum fin efficiency by varying the values of each parameter.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
• /
• pp.110-114
• /
• 2009

The model to calculate the solar radiation at the surface was developed and the annual global solar radiation calculated by the model was compared with the KMA(Korea Meteorological Administration) surface measured data The difference between calculated and measured values was distinguished clearly because of the calibration problem of the pyranometer, but the global distribution of solar radiation calculated by the model was very similar to NREL(National Renewable Energy Laboratory) result of USA.

• 대한기계학회논문집
• /
• 제18권2호
• /
• pp.519-528
• /
• 1994

Degradation problem due to long term service in machine or structure is now one of important problems in whole industrial field. In this study, pressure vessel steel, Cr-Mo steel, which was used more than 60,000 hours, was surface-modified by laser beam radiation for the improvement of fatigue strength. To find out optimum radiation condition, hardness, residual stress measurement and fatigue tests were carried out with the specimen of different radiation conditions. Experimental results show that micro-hardness values on the surface of the radiated specimens were approximately 2.2 times higher than those of un-radiated ones. In the depth direction of the specimen, hardness on the surface showed maximum value and was decreased at the inside the specimen. Different hardness values are due to the energy density Q which was absorbed by the specimen. Fatigue tests show that fatigue life was improved by the compressive residual stress after laser beam radiation. However, some specimens with differednt conditions show the shorter fatigue life. It means that laser beam radiation with optimum parameter can improve thae fatigue strength.

• 한국소음진동공학회논문집
• /
• 제22권8호
• /
• pp.800-807
• /
• 2012

In this paper, radiation efficiency of the plate surround by an infinite rigid baffle is studied. The plate is simply supported and one side is in contact with air, while other side with water. The pressure and normal velocity over the plate surface are assumed as modal summations, from which a set of linear equations is obtained for fluid-structure coupled problem. It is shown that neglect of the cross modes results in overestimation of the radiation efficiency specifically for mid-frequency ranges. Based on the fact that the responses are mainly determined from the first few cross modes in addition to the diagonal terms, a new algorithm is proposed, where banded matrix is iteratively solved in computing radiation efficiency. In numerical examples, it is found that radiation efficiency obtained from banded matrix is in excellent agreement with the one from the full matrix, while computing time is significantly reduced. It is also found that as frequency grows larger, radiation efficiency considering only diagonal terms is a good approximation.

• 한국항해항만학회지
• /
• 제28권3호
• /
• pp.199-205
• /
• 2004

라디에이션(radiation) 문제를 해결하기 위해서 중합격자법을 개발하였다. 중합격자계는 이동격자계와 고정격자계로 이루어져 있으며, 이동격자계는 운동하는 물체에 적용되어 운동하는 물체와 동시에 이동된다. 이러한 수치계산법은 자유표면 부근에서 운동하는 몰수평판에 작용하는 라디에이션 유체력을 계산하는데 응용되었다. 현재의 수치계산법에 의한 결과는 실험값 및 선형포텐셜 이론에 의한 결과와 상호 비교하였으며, 수치계산의 신뢰성을 확인하였다. 그리고, 몰수평판에 작용하는 비선형 점성감쇄효과에 대하여 평가하였다.

• 한국지진공학회논문집
• /
• 제19권1호
• /
• pp.37-43
• /
• 2015

This paper presents a detailed procedure for a nonlinear soil-structure interaction of a seismically isolated NPP(Nuclear Power Plant) structure using the boundary reaction method (BRM). The BRM offers a two-step method as follows: (1) the calculation of boundary reaction forces in the frequency domain on an interface of linear and nonlinear regions, (2) solving the wave radiation problem subjected to the boundary reaction forces in the time domain. For the purpose of calculating the boundary reaction forces at the base of the isolator, the KIESSI-3D program is employed in this study to solve soil-foundation interaction problem subjected to vertically incident seismic waves. Wave radiation analysis is also employed, in which the nonlinear structure and the linear soil region are modeled by finite elements and energy absorbing elements on the outer model boundary using a general purpose nonlinear FE program. In this study, the MIDAS/Civil program is employed for modeling the wave radiation problem. In order to absorb the outgoing elastic waves to the unbounded soil region, spring and viscous-damper elements are used at the outer FE boundary. The BRM technique utilizing KIESSI-3D and MIDAS/Civil programs is verified using a linear soil-structure analysis problem. Finally the method is applied to nonlinear seismic analysis of a base-isolated NPP structure. The results show that BRM can effectively be applied to nonlinear soil-structure interaction problems.

• 천문학논총
• /
• 제30권2호
• /
• pp.297-299
• /
• 2015

In this paper we have examined the linear stability of triangular equilibrium points in the photogravitational restricted three body problem when both primaries are triaxial rigid bodies, the bigger one an oblate spheroid and source of radiation. The orbits about the Lagrangian equilibrium points are important for scientific investigation. A number of space missions have been completed and some are being proposed by various space agencies. We analyze the periodic motion in the neighbourhood of the Lagrangian equilibrium points as a function of the value of the mass parameter. Periodic orbits of an infinitesimal mass in the vicinity of the equilibrium points are studied analytically and numerically. The linear stability of triangular equilibrium points in the photogravitational restricted three body problem with Poynting-Robertson drag when both primaries are oblate spheroids has been examined by A. Kumar (2007). We have found the equations of motion and triangular equilibrium points for our problem. With the help of the characteristic equation we have discussed stability conditions. Finally, triangular equilibrium points are stable in the linear sense. It is further seen that the triangular points have long or short periodic elliptical orbits in the same range of ${\mu}$.

• 한국방사선학회논문지
• /
• 제16권7호
• /
• pp.815-824
• /
• 2022

현행 방사선안전관리 제도가 대학에서 방사선 실습을 하는 경우에도 적용되어 방사선 실습 교육의 부실과 방사선학의 발전을 저해할 우려가 있다. 이에 대한 방사선(학)과 교수협의회는 전국 방사선학과 학과장을 대상으로 각 대학의 방사선 실습 교육에 대한 관리체계 및 방사선안전관리 제도의 현실을 파악하기 위해 설문조사를 실시하였다. 설문조사를 통해 현행 방사선(학)과의 방사선안전관리에 대해 「원자력안전법」을 적용받는 것은 과도한 제한이며, 효과성도 크지 않다는 것을 알 수 있었다. 또한 방사선학과 실습 교육은 보건의료인 양성을 목적으로 하고 있기에 보건복지부 및 질병관리청의 지휘를 받아야 하나 원자력안전관리위원회의 관리감독을 받는 문제가 있다. 본 논문에는 「원자력안전법」 시행령을 개정하여 수시출입자의 정의에서 실습 교육을 수강하는 학생을 제외하는 방안을 기본으로 제안하였다. 추가적으로 첫째, 「고등 교육법」 일부개정법률안에 따른 방안, 둘째, 「의료법」 제37조 개정을 통해 보건복지부의 감독을 받는 방안, 셋째, 「의료기사에 관한 법률」 제20조의2를 신설하여 보건복지부의 감독을 받는 3가지 방안을 제안하였다.

• Archives of Plastic Surgery
• /
• 제38권6호
• /
• pp.803-807
• /
• 2011

Purpose: The safety of radiation therapy after breast reconstruction using transverse rectus abdominis myocutaneous (TRAM) flap is still being debated, and few studies exist on the outcome of irradiation after immediate TRAM breast reconstruction. Some authors presented satisfactory outcomes after adjuvant radiation therapy on reconstructed breast with pedicled TRAM flap, while others reported significant post radiation changes of the flap. Effect of radiation therapy on TRAM flap was evaluated to see whether adjuvant radiation therapy was tolerable. Methods: 1000 immediate TRAM breast reconstruction was done by a single surgeon from July, 2001 to December, 2009. Among them 105 patients required adjuvant radiation therapy because of advanced disease or locoregional recurrence. Fat necrosis, radiation fibrosis, mastectomy skin flap necrosis, need for secondary touch up procedures, patient satisfaction were evaluated. Results: The incidence of fat necrosis was 10.5% and significant radiation fibrosis occurred in only one patient. Delayed wound problem did not occur during or after irradiation. Secondary touch-up procedures were performed in 12.3%, the most common being fat graft (8.6%). Average patient satisfaction score was 8.62/10, which was not significantly different from the authors' previous report involving all the TRAM patients (8.50). Conclusion: Radiation therapy did not increase the complication rate significantly. Aesthetic result was affected but was tolerated in most cases. The fear of adjuvant radiation is not a negative factor in selecting immediate breast reconstruction with TRAM flap.