• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.63.2-63.2
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• 2010

Solar radiation data are used in several forms and for a variety of purposes. The most detailed information we have is beam and diffuse solar radiation on a horizontal surface, by hours, which is useful in simulations of solar processes. Daily data are more often available and monthly total solar radiation on horizontal surface can be used in some process design methods. However, as performance is generally not linear with solar radiation, the use of average may lead to serious errors if non-linearities ara not taken into account. It is also possible to reduce radiation data to more manageable forms by statistical methods. The control of the quality of most measurements is relegated to the control of the measuring instruments and measuring processes themselves. An accurate measurement will usually result from the use of a high-quality instrument that has been accurately calibrated and is properly used by a qualified individual.

• Journal of the Korean Institute of Navigation
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• v.4 no.2
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• pp.1-6
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• 1980

Computer simulation results on the radiation pattern of an ultrasonic beam by the plurall arrangement of the transducers were reported by Sin (1979). This paper describes on the measurement of radiation pattern in case of one vibrox transducer and two vibrox transducers by varying the interval between the transducers. The measured results obtained are as follows; 1. Radiation wave of ultrasonic transducer is propagated to diffuse with spherical wave from center of transducer. 2. In case of one vibrox transducer, the greater the length of transducer, the sharper becomes the radiation pattern. 3. In case of two vibrox transducers, the maine lobe is revealed at the center of two transducers, it is shown difficult to make control freely of radiation pattern by varying merely the interval of transducers.

• Journal of The Korean Astronomical Society
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• v.25 no.2
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• pp.111-128
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• 1992

Infrared emissions from spherical dust, clouds are calculated using quasi-diffusion method. We have employed graphite-silicate mixture with power-law size distribution for the dust model. The grains are assumed to be heated and cooled by radiative processes only. The primary heating source is diffuse interstellar radiation field. hut the cases with an embedded source are also considered. Since graphite grains have higher temperature than silicate grains, the observed IR emission is mainly due to graphite grains, unless the fraction of graphite grains is negligibly small. The color temperature of Bok globules obtained from IRAS 60 and $100{\mu}m$ data are found to be consistent with the dust cloud with graphite-silicate mixture exposed to average interstellar radiation field. The color temperature is sensitive to the external radiation field, but rather insensitive to the size distribution of the grains. We found that the density distribution can be recovered outside the beam size using the inversion technique that assumes negligible optical depth. However, the information within the beam size is lost for if beam convolved intensity distributions are used in deriving density profile.

• Advances in Energy Research
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• v.8 no.2
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• pp.111-123
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• 2022

Solar Energy is the energy of solar radiation carried by them in the form of heat and light. It can be converted into electricity. Solar potential depends on the site's atmosphere; the solar energy distribution depends on many factors, e.g., turbidity, cloud types, pollution levels, solar altitude, etc. We estimated solar radiation with the help of the Ashrae clear-sky model for three locations in Pakistan, namely Pasni, Gwadar, and Jiwani. As these locations are close to each other as compared to the distance between the sun and earth, therefore a slight change of latitude and longitude does not make any difference in the calculation of direct beam solar radiation (BSR), diffuse solar radiation (DSR), and global solar radiation (GSR). A modified formula for declination angle is also developed and presented. We also created two different models for Ashrae constants. The values of these constants are compared with the standard Ashrae Model. A good agreement is observed when we used these constants to calculate BSR, DSR, GSR, the Root mean square error (RMSE), Mean Absolute error (MABE), Mean Absolute percent error (MAPE), and chisquare (χ²) values are in acceptance range, indicating the validity of the models.

• Korean Journal of Audiology
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• v.23 no.1
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• pp.59-62
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• 2019

Primary tumors arising from the external auditory canal (EAC) are rare. We describe two cases of mass lesions within the EAC causing slowly progressive hearing loss without otorrhea or otalgia. Otoendoscopic examination demonstrated total obstruction of the EAC, and pure tone audiometry revealed conductive hearing loss. Based on the findings of the histopathologic examination, one patient was diagnosed with venous hemangioma that was treated using surgical resection, and the other patient was diagnosed with diffuse large B-cell lymphoma (DLBCL) that was treated using external-beam radiation therapy. Although primary tumors in the EAC are rare, both benign tumors such as venous hemangiomas and malignant lesions such as DLBCL should be considered as possible differential diagnoses of mass lesions in the EAC.

• Journal of Audiology & Otology
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• v.23 no.1
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• pp.59-62
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• 2019

Primary tumors arising from the external auditory canal (EAC) are rare. We describe two cases of mass lesions within the EAC causing slowly progressive hearing loss without otorrhea or otalgia. Otoendoscopic examination demonstrated total obstruction of the EAC, and pure tone audiometry revealed conductive hearing loss. Based on the findings of the histopathologic examination, one patient was diagnosed with venous hemangioma that was treated using surgical resection, and the other patient was diagnosed with diffuse large B-cell lymphoma (DLBCL) that was treated using external-beam radiation therapy. Although primary tumors in the EAC are rare, both benign tumors such as venous hemangiomas and malignant lesions such as DLBCL should be considered as possible differential diagnoses of mass lesions in the EAC.

• Solar Energy
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• v.9 no.3
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• pp.3-12
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• 1989

Semi-greenhouse type solar-dehumidification drying of oak was carried out to investigate the possibility to dry wood using solar energy in Korea. The energy balance equation was set up, considering all the energy requirements, and the solar radiation was calculated to analyze the efficiencies of solar dryer with and without the dehumidifier. The average temperature inside dryer and collector rose up to $52^{\circ}C$ and $70^{\circ}C$, respectively. The average daily total beam, diffuse, and ground-reflected radiations were 7.27MJ, 8.70MJ, and 0.33MJ on the roof and 2.08MJ, 4.84MJ, and 5.37MJ on the south wall collector, respectively. Heat efficiency of solar dryer was 14.04% with dehumidifier and 13.13% without dehumidifier. The energy required to remove 1g of water from wood was 0.0289MJ/g in solar-dehumidification drying and 0.0310 MJ/g in semi-greenhouse type solar drying.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.56.1-56.1
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• 2017

When turbulent motions perturb magnetic field lines and produce magnetic fluctuations, the perturbations leave imprints of turbulence statistics on magnetic field. Observation of synchrotron radiation is one of the easiest ways to study turbulent magnetic field. Therefore, we study statistical properties of synchrotron polarization emitted from media with magnetohydrodynamic (MHD) turbulence, using both synthetic and MHD turbulence simulation data. First, we obtain the spatial spectrum and its derivative with respect to wavelength of synchrotron polarization arising from both synchrotron radiation and Faraday rotation. The study of spatial spectrum shows how the spectrum is affected by Faraday rotation and how we can recover the statistics of underlying turbulent magnetic field as well as turbulent density of electrons from interferometric observations that incorporate the effects of noise and finite telescopic beam size. Second, we study quadrupole ratio to quantitatively describe the degree of anisotropy introduced by magnetic field in the presence of MHD turbulence. We consider the case that the synchrotron emission and Faraday rotation are spatially separated, as well as the situation that the sources of the synchrotron radiation and thermal electrons causing Faraday rotation exist in the same region. In this study, we demonstrate that the spectrum and quadrupole ratio of synchrotron polarization can be very informative tools to get detailed information about the statistical properties of MHD turbulence from radio observations of diffuse synchrotron polarization.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.316-321
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• 2000

In this study, heat collecting performance was study of flat plate solar collector by the angle. A method of study on were made turn out artificial sun by the angle of 0, 15, 30 degrees. The heat performances were measured the tube array surface temperature by thermo-couple. The winter season natural condition for 4 times on the angles of various general and emboss glass at optimum distance(0.68m) calculated of between sun and solar collector. To sum up temperature rise is appear more or less that emboss glass is all the better for general glass. The temperature variable at below of 30 degree was appear very less. The maximum performance of this system at that it is tilt angle of 30 with general glass is appear Q:11.54(kcal/min) and ${\Delta}T=18.9^{\circ}C$.

• Atmosphere
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• v.21 no.2
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• pp.131-142
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• 2011

Spectral solar irradiances were observed using a visible and UV Multi-Filter Rotating Shadowband Radiometer on the rooftop of the Science Building at Yonsei University, Seoul ($37.57^{\circ}N$, $126.98^{\circ}E$, 86 m) during one year period in 2006. 1-min measurements of global(total) and diffuse solar irradiances over the solar zenith angle (SZA) ranges from $20^{\circ}$ to $70^{\circ}$ were used to examine the effects of clouds and total optical depth (TOD) on enhancing four solar irradiance components (broadband 395-955 nm, UV channel 304.5 nm, visible channel 495.2 nm, and infrared channel 869.2 nm) together with the sky camera images for the assessment of cloud conditions at the time of each measurement. The obtained clear-sky irradiance measurements were used for empirical model of clear-sky irradiance with the cosine of the solar zenith angle (SZA) as an independent variable. These developed models produce continuous estimates of global and diffuse solar irradiances for clear sky. Then, the clear-sky irradiances are used to estimate the effects of clouds and TOD on the enhancement of surface solar irradiance as a difference between the measured and the estimated clear-sky values. It was found that the enhancements occur at TODs less than 1.0 (i.e. transmissivity greater than 37%) when solar disk was not obscured or obscured by optically thin clouds. Although the TOD is less than 1.0, the probability of the occurrence for the enhancements shows 50~65% depending on four different solar radiation components with the low UV irradiance. The cumulus types such as stratoculmus and altoculumus were found to produce localized enhancement of broadband global solar irradiance of up to 36.0% at TOD of 0.43 under overcast skies (cloud cover 90%) when direct solar beam was unobstructed through the broken clouds. However, those same type clouds were found to attenuate up to 80% of the incoming global solar irradiance at TOD of about 7.0. The maximum global UV enhancement was only 3.8% which is much lower than those of other three solar components because of the light scattering efficiency of cloud drops. It was shown that the most of the enhancements occurred under cloud cover from 40 to 90%. The broadband global enhancement greater than 20% occurred for SZAs ranging from 28 to $62^{\circ}$. The broadband diffuse irradiance has been increased up to 467.8% (TOD 0.34) by clouds. In the case of channel 869.0 nm, the maximum diffuse enhancement was 609.5%. Thus, it is required to measure irradiance for various cloud conditions in order to obtain climatological values, to trace the differences among cloud types, and to eventually estimate the influence on solar irradiance by cloud characteristics.