• Journal of Environmental Science International
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• v.21 no.7
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• pp.815-824
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• 2012

The purpose of this study was to analyze the meteorological characteristics of wintertime high PM10 concentration episodes in Busan. $PM_{10}$ concentration has been reduced for the past four years and recorded near or exceeded 100 ${\mu}g/m^3$ (national standard of $PM_{10}$). High concentration episodes in Busan were 6 case, $PM_{2.5}/PM_{10}$ ratio was 0.36~0.39(mean 0.55). High $PM_{10}$ concentration occurred during higher air temperature, more solar radiation and sunshine, lower relative humidity, and smaller cloud amount. Synoptically, it also occurred when Busan was in the center or the edge of anticyclone and when sea breeze intruded. An analysis of upper air sounding showed that high $PM_{10}$ concentration occurred when surface inversion layer and upper subsidence inversion layer existed, and when boundary layer depth and vertical mixing coefficient were low. An analysis of backward trajectory of air mass showed that high $PM_{10}$ concentration was largely affected by long range transport considering that it occurs when air mass is intruded from China.

• The Journal of Korean Physical Therapy
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• v.26 no.1
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• pp.21-26
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• 2014

Purpose: This study examined the effect of trunk stabilization exercise upon the lumbar stabilization and foot pressure on an unstable surface with back pain. Methods: The subjects of the study were 10 patients who showed the symptom of back pain with excessive lumbar curve. This study was 4 weeks, 30 minutes per session, three times a week for a total of 12 times as a result of exercise radiation imaging device and foot pressure analyzer. Results: The sacrohorizontal angle was statistically significant(p<0.05). Comparison of the difference between static right and left foot pressure ratio analysis was statistically significant(p<0.05). Dynamic right and left foot pressure comparisons for the difference was statistically significant in the analysis (p<0.05). Conclusion: Trunk stabilization exercise and the reduction of the excessive sacrohorizontal angle, and static and dynamic foot pressure imbalance reduced left and right.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.898-906
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• 2017

This paper discusses the efficient high fidelity calculation of external thermal loads of a spacecraft on its orbit. Thermal loads to a spacecraft consist of three major components, direct solar radiation, earth reflection of solar rays, and earth irradiation. With the assumption that both earth reflection and earth emission are diffuse, thermal loads from earth surface divided into pieces of segments to satellite surfaces are individually calculated and summed over. By using analytical integration of both reflected and emitted heat load by earth, high rate of numerical convergence is achieved and the results are even exactly calculated in special cases. Moreover, KD tree ray tracing is employed in the calculation of thermal load to determine whether the radiated ray is obstructed or not by satellite structure.

• Advances in materials Research
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• v.6 no.1
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• pp.1-12
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• 2017

The aim of the work was to evaluate the effect of ultraviolet-ozone ($UV-O_3$) irradiation with different times on the structure and thermal properties of hydroxypropyl methylcellulose (HPMC) in the form of a thin film to be used as bioequivalent materials according to their important broad practical and medical applications. HPMC thin films were exposed to $UV-O_3$ radiation in air at a wavelength of 184.9 nm.The beneficial effects of this treatment on the crystallinity and amorphousity regions were followed by X-ray diffraction technique and FTIR spectroscopy. Differential scanning calorimetry, thermogravimetric and differntial thermal analyses were used in order to study the thermal properties of HPMC samples following the process of photodegradation. The obtained results indicated that the rate of degradation process was increased with increasing the exposure time. Variations in shape and area of the thermal peaks were observed which may be attributed to the different degrees of crystallinity after exposing the treated HPMC samples. This meant a change in the amorphousity of the treated samples, the oxidation of its chemical linkages on its surface and its bulk, and the formation of free radical species as well as bond formation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.9
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• pp.455-462
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• 2017

The purpose of this study is to analyze heating and cooling load variation due to envelope retrofits in an old school building. In a previous study, envelope retrofit of an old school building resulted in annual energy consumption reduction. However, cooling energy consumption increased with the envelope retrofit. This is because of high internal heat generation rates in school buildings and internal heat cannot escape through windows or walls when the envelope's thermal performance improves. To clarify this assumption, thermal performance changes due to envelope retrofits were analyzed by simulation. Results revealed indoor temperature and inner window surface temperature increased with high insulation level of windows. Indoor heat loss through windows by conduction, convection and radiation decreased and resulted in an increase of cooling load in an old school building. From results of this study, energy saving impact of envelope retrofits in an old school building may not be significant because of high internal heat gain level in school buildings. In case of replacing windows in school buildings, local climate and internal heat gain level should be considered.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.49-53
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• 2001

A conventional flame type gas combustion major portion of heat is transferred to the body by convection due to small radiant ability of the gas flame. Increasing the radiation component of heat flux in the combustion zone allows to augment the efficiency of gas utilization. Such effect can be reached by using radiative gas burner applied to metal mesh combustion. Basically the gas radiant burner consists of metallic mesh of high heat resisting steels. In terms of this regards, we have made the burner consisted of metal mesh and measured the radiative flame stability of natural gas/air mixture on the metal mesh burner. The pressure loss through the metal mesh is defined by pressure-velocity slope. The more increased the pressure-velocity slope of the metal mesh is, the wider the stable zone of radiave flame on the metal mesh burner is. And the augmentation of mixture flowrate through the metal mesh make narrow the permissible range of equivalence ratio.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.521-524
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• 2001

The anaerobic continuous reactor, which was filled with a sludge of anaerobic digestion from Sooyoung sewage treatment plant, was supplied with synthetic wastewater of various concentration. After changing to substrate concentration, 디 1is research indicated that attached biomass was kept constant after attachment 23 days. In SEM photographs. shape and structure of biofilm could be observed, but bacteria species and methanogens were not identified. A large number of methanogenic bacteria were showed on the surface of PE substratum by fluorescence under 480nm of radiation.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.497-505
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• 2003

This paper describes a computational approach to the quantification of primary damage under irradiation and demonstrates the effect of neutron energy spectra on the formation of the displacement cascade. The development of displacement cascades in ${\alpha}-Iron$ has been simulated using the MOLDY code - a molecular dynamics code for simulating radiation damage. The primary knock-on atom energy, key input to the MOLDY code, was determined from the SPECTER code calculation on two neutron spectra. The two neutron spectra include; (i) neutron spectrum in the instrumented irradiation capsule of the high-flux advanced neutron application reactor (HANARO), and (ii) neutron spectrum at the inner surface of the reactor pressure vessel steel for the Younggwang nuclear power plant No.5 (YG 5). Minor differences in the normalized neutron spectra between the two spectra produce similar values of PKA energy, which are 4.7 keV for HANARO and 5.3 keV for YG 5. This similarity implies that primary damage to the components of the commercial nuclear reactors should be well simulated by irradiation in the HANARO. Moreover, the application of the MD calculations corroborates this statement by comparing cascades simulation results.

• Journal of radiological science and technology
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• v.11 no.1
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• pp.17-23
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• 1988

As the reutilizing method of exhausted screen, authors used it as a filter and compared with the aluminium filtration. The results are as followed; 1. One sheet of gadolinium front screen has the same radiation absorption as $2.8{\sim}3.3\;mm$ Al equivalent and regular tungsten screen $2.3{\sim}2.7mm$ Al. 2. HVL after Gd-screen filtration was less than the values after aluminium and tungsten-screen filtration. And, image definition with Gd-screen filtration was better than other two cases. Ana surface dose to produce a same film density was more than other two cases. It will be very useful to apply, Gd-screen filter in clinics as it has no deficiency of image quality.

• Journal of radiological science and technology
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• v.17 no.2
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• pp.29-35
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• 1994

Tomographic examination requires several times of exposure usually, therefore, reduction of radiation dose per exposure without loss of image quality proves of great benefit to patient. We compared the exposure doses under the following experimental conditions, A and B. A is the combination of SRO 380(rare earth screen) and SRH(high contrast film) with additional Cu filters or without. B is the widely used combination which is BH-III and Cronex-4 without additional filter. As a result, comparing with the condition B, the condition A with additional filter of Cu 0.15 mm + Al 0.7 mm, Cu 0.4 mm+ Al 0.4 mm and Cu 0.8 mm showed better Image quality and lower surface dose, 44 %, 31 % and 24 % of the condition B, respectively.