• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.672-680
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• 2017

A solar photovoltaic system is composed of a module mounting structure, supporting trunk, and a control unit that supplies generated electrical power to an external power grid or a load. The efficiency of the system depends on the incident solar light, so the mounting structure is installed to face the sun. However, because the sun always moves, systems that track the sun have better efficiency than fixed systems. The structure experiences wind pressure, snow load, seismic load, and structure weight. The wind pressure has the most serious effect on the structure. The pressure was obtained using finite element method for various gaps between modules and angles between the panel and the ground. The wind pressure is lowest when the gap is zero, and it increases with the inclination angle. Based on the results, a mounting structure module was designed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.831-838
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• 2016

The disaster preventing system using vegetation has been growing in the field of coastal engineering in recent years. To analyze wave and flow fields under nonlinear interactions between tsunami and vegetation, the purpose of this study is to evaluate newly-developed 3-D numerical wave tank including energy dissipation by tsunami-vegetation interaction based on existing N-S solver with porous body model. Comparing numerical results using mean drag coefficient and dynamic drag coefficient due to Reynolds number to existing experimental results it is revealed that computed results considering the dynamic drag coefficient are in good agreement with the laboratory test results for time-domain waveform. In addition, the calculated transmission coefficients of solitary waves in various vegetation densities and incident wave heights are also in good agreement with the experimental values. This confirms the validity and effectiveness of the developed 3-D numerical wave tank with the fluid resistance by vegetation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.7
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• pp.112-124
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• 1989

In order to evaluate imaging performance of newly developed digital radiography system which requires scanning time as short as 0.7 sec and patient exposure as low as 3 mR, we have investigated its imaging and physical properties such as sensitivity characteristic, scatter fraction, detective quantum efficiency, modulation transfer function, and contrast detail diagram. The results show that the digital radiography system has linear sensitivity to the incident energy, and superior contrast resolving power with less X-ray exposure than conventional film-screen system. These performances are resulted from excellent scatter rejection capability and high detective quantum efficiency of digital radiography system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.64-72
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• 2009

In this paper, a high efficiency 2.45 GHz rectenna with a microstrip patch antenna and a dual-mode band-pass filter in which the 2nd and 3rd harmonics are suppressed, is presented. From the experimental results, the 2.45GHz rectenna using 3rd harmonic suppressed dual-mode BPF shows the conversion efficiency of 41.6% with incident power density of 0.3 mW/cm2 and the received power of 1.66 mW. This result shows high conversion efficiency because the received power of this rectenna is lower than other rectennas to be compared with. This rectenna can be applied to the WPT (Wireless Power Transmission) field for energy harvesting. Also, it is expected to be used to provide the stand-by power for the low power devices for USN, and wireless power transfer in sensor application of MEMS devices.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.3
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• pp.19-32
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• 2003

In the conventional photorefractive joint transform correlator(PRJTC), the intensity ration of input signal-to-pump beam should be large enough to saturate two-beam coupling transfer function to obtain a desired correlation result. As a result, the signal-to-noise ratio(SNR) of correlation result is decreased in a noisy input image. In this paper, we propose the improved method for increasing the SNR of the PRJTC by using the characteristics of BaTiO$_3$. We stop the energy transfer saturating by low intensity ratio of input beam and realize a short length of effective interaction in BaTiO$_3$ by making large incident angle of the signal beam. So the gain in high frequency area is decreased and the gain in low frequency area comes up to the saturation gain of the beam coupling transfer function. Therefore the SNR is improved in noisy input image and the PRJTC can be easily realized by low intensity ratio of input beam.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.15-21
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• 2007

Using field observations, this study estimated the total weight and types of marine debris along the coast of Jinu Island in the Nakdong River Estuary after typhoons Usagi and Nari had passed. A numerical wave m며el was used to calculate the spatial wave height distribution at the time of the typhoons' passage. This study found that the total accumulation of marine debris deposited on the coast after the two typhoons had passed was about $5,769.86kg/day/km^2$ at this sitε which was 14.42 times more than during normal weather. The wave height distribution in the sea off Jinu Island, based on numerical modeling， was $4.1^{\sim}3.5$ m, which was 1.0-2.5 times greater than for the case of other islands. Therefore, it is likely that the concentration of wave energy led to the deposition of marine debris.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.3
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• pp.1453-1461
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• 2016

Regarding 'mate' intake (infusion of Ilex paraguariensis herb, a staple beverage in temperate South American regions), most epidemiologic studies showed positive associations with risk of some cancers, (e.g. upper aerodigestive tract), but evidence on breast cancer (BC) risk is limited to a previous multi-site study, which reported a non significant odds ratio [OR]=0.85, 95% confidence interval [95% CI] 0.67-1.09, p for trend=0.31) for the highest quartile of intake. The present study was conducted in order to further assess associations of 'mate' intake with BC risk. We combined two databases of women belonging to public and private healthcare hospitals. The sample included 572 BC incident cases and 889 controls interviewed with a specific questionnaire featured by socio-demographic, reproductive and lifestyle variables, and a food frequency questionnaire of 64 items, also analyzing 'mate' intake (consumer status, daily intake, age at start, age at quit, duration of habit, intensity of intake). ORs and their 95%CI were calculated through unconditional logistic regression, adjusting for relevant potential confounders. The highest quartile of 'mate' intake was inversely associated with BC risk (OR=0.40, 95%CI 0.26-0.57, p for trend <0.001). Stratified analyses also displayed strong significant inverse associations for 'mate' in frequent tea drinkers (OR=0.22), high energy intake (OR=0.23), high body mass index (OR=0.29) and in postmenopausal women (OR=0.36), among other results. As conclusions, we found evidence of a significant inverse association for 'mate' intake and BC risk.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3911-3916
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• 2012

Background: The objective of this study WAS to describe cancer incidence rates and trends among THE Hong Kong population for the period 1983-2008. Methods: Incident cases and population data from 1983 to 2008 were obtained from the Hong Kong Cancer Registry and the Census and Statistics Department, respectively. Agestandardized incidence rates (ASIR) were estimated and joinpoint regression was applied to detect significant changes in cancer morbidity. Results: For all cancers combined, the ASIR showed declining trends (1.37% in men, 0.94% in women), this also being the case for cancers of lung, liver, nasopharynx, stomach, bladder, oesophagus for both genders and cervix cancer for women. With cancer of thyroid, prostate, male colorectal, corpus uteri, ovary and female breast cancer an increase was evident throughout the period. The incidence for leukemia showed a stable trend since early 1990s, following an earlier decrease. Conclusion: Although overall cancer incidence rates and certain cancers showed declining trends, incidence trends for colorectal, thyroid and sex-related cancers continue to rise. These trends in cancer morbidity can be used as an important resource to plan and develop effective programs aimed at the control and prevention of the spread of cancer amongst the Hong Kong population. It is particularly useful in allowing projection of future burdens on the society with the increase in certain cancer incidences.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.267-273
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• 2012

Solar reforming of methane with CO2 was successfully tested with a direct irradiated absorber on a parabolic dish capable of 5kWth solar power. And the new type of double-layer absorber-the front layer, porous metal foam which absorbs the radiation and transfers the heat from material to gas, and the back layer, catalytically-activated metal foam-was prepared, and its activity was tested by using electric furnace. Ni was applied as the active metal on the gamma-Al2O3 coated Ni metal foam for the preparation of the catalytically-activated metal foam layer. Compared to conventional direct irradiation of the catalytically activated metal foam absorber, this new type of double layer absorber is found to exhibit a superior reaction and thermal storage performance at the fluctuating incident solar radiation. In addition, unlike direct irradiation of the foam absorber, double layer absorber has better thermal resistance, which prevents the emergence of cracks caused by mechanical or thermal shock. The total solar power absorbed reached up to 3.25kW and the maximum CH4 conversion was almost 59%.

• Korean Journal of Optics and Photonics
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• v.21 no.1
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• pp.16-20
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• 2010

In this study, we have fabricated a fiber-optic dosimeter using an organic scintillator and a plastic optical fiber. The dosimeter measure skin dose and percentage depth dose in a build-up region for an incident high energy photon beam. The scintillating light generated in the organic sensor probe embedded in a solid water phantom is guided by 30 m plastic optical fiber to a light-measuring device such as a PMT or an electrometer. In addition, using a fiber-optic dosimeter or a GAFCHROMIC EBT film, skin dose and percentage depth dose in the build-up region are measured and compared.