• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.4
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• pp.203-210
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• 2020

Spatial variation of diffracting wave amplitudes along a semi-infinite breakwater is investigated using the analytical solution of Penney and Price (1952) for wave diffraction. On the front side of the breakwater, the fluctuation of wave amplitudes due to diffracting waves would cause a wave force greater than that of superposed incident and reflected waves. The diffracting wave phase varies in circular shape from the breakwater tip of (x, y) = (0, 0) whereas the incident and reflected wave phases vary in planar shape. So, the total wave amplitude of the incident (or reflected) waves and the diffracting waves would fluctuate at a position away from the energy discontinuity line. The position (x, y) = (0, y) on the front and lee sides of the breakwater is at a distance y(π/2 - β) of the point on the energy discontinuity line along the diffracting wave crest line. The degree of reduction of the diffraction wave energy is proportional to the distance from the point on the energy discontinuity line along the diffracting wave crest line. Therefore, the diffracting wave amplitudes on the front and lee sides of the breakwater would be inversely proportional to the square root of y(π/2 - β).

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2879-2886
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• 2012

In order to thoroughly analyze risk factors of breast cancer (BC) in premenopausal Uruguayan women, a case-control study was carried out at the Pereira Rossell Women's Hospital, Montevideo, where 253 incident BC cases and 497 frequency-matched healthy controls were interviewed on menstrual and reproductive story, were administered a short food frequency questionnaire and undertook a series of body measurements necessary to calculate body composition and somatotype. Odds ratio (OR) coefficients were taken as estimates of relative risk derived from unconditional logistic regression. Among the classical risk factors, only the family history of BC in first degree relatives was significantly associated with risk of premenopausal BC (OR=2.20, 95% CI 1.33-3.62). Interestingly, this risk factor was found to be stronger in women of ages >40 (OR=4.05, 95% CI 2.10-7.81), late menarche (OR= 2.39, 95% CI 1.18-4.85), early age for their first delivery (OR=3.02, 95% CI 1.26-7.22), short time between menarche and first delivery (OR=3.22, 95% CI 1.29-8.07), and with high parity (OR=4.10, 95% CI 1.79-9.36), although heterogeneity was detected only for age and parity. High consumption of red meat was positively associated with the disease risk (OR=2.20, 95% CI 1.35-3.60), in the same way as fried foods (OR=1.79, 95% CI 1.12-2.84). Conversely, a high intake of plant foods displayed a protective effect (OR=0.41, 95% CI 0.26-0.65). Except for hypertension (OR=1.55, 95% CI 1.03-2.35), none of the analyzed components of metabolic syndrome were associated to BC risk. Particular increases of risk for premenopausal BC were found for family history in first degree relatives in certain subsets derived from the menstrual-reproductive history. Preventive strategies could broaden their scope if new studies confirm the present results, in view of the limited prevention measures that premenopausal BC currently has.

• Korean Journal of Optics and Photonics
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• v.21 no.4
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• pp.175-178
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• 2010

A transmission type color filter based on a thin film Ag-$SiO_2$-Ag etalon was proposed and realized in a quartz substrate. The device could acquire infrared suppressed transmission and wide effective area compared to costly e-beam lithography and laser interference lithography. The FDTD method was introduced to take into account the effect of the dispersion characteristics of the silver metal and the thickness thereof. Three different color filters were devised: The cavity length for the red, green and blue filters were 160 nm, 130 nm, and 100 nm respectively, with the metal layer unchanged at 25 nm. The observed center wavelengths were measured at 650 nm, 555 nm, and 480 nm for the red, green, and blue devices; the corresponding bandwidths were about 120 nm, 100 nm, and 120 nm; and the peak transmission for all was ~60%. Finally the relative transmission was measured to decline with the angle of the incident beam with the rate of 1%/degree.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.1
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• pp.83-91
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• 1996

The SPICE circuit analysis program has a limited math capability and, in general, cannot be used for RF and microwave simulation because a complex arithmetic is required to compute S-parameters from node voltages. This paper presents two test bench models that can be used to obtain node voltages proportional to incident, reflected, and transmitted signals. From SPICE computed node voltages, S-parameters are computed using the math capability of the PSPICE post processor, PROBE, as an example for a low-pass filter consisting of transmission line sections. The results of this example are compared with another high frequency circuit analysis program, TOUCHSTONE. The difference between the results of these two programs in magnitude was less than 0.003 and in phase was a few tenths of a degree. By using these test benchs to simulate a filter, RF and microwave analysis can be made with the SPICE, which can be a cost-effective and readily available computational tool for educators and practicing engineers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.347-350
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• 2017

In this paper, we implemented a real-time 2.4 GHz direction finding system using a time-modulated array(TMA) and an Universal Software Radio Peripheral(USRP). Our system consists of two commercial monopole antennas, self-designed switch board, and an USRP, and it is controlled using LabVIEW program in real-time. From measured results, it is verified that our system can exactly detect the incident angle within 4 degree in the range of 30 degree. Our direction finding system has advantages of a simple hardware architecture than conventional one with multiple receivers, and a simple algorithm only by using a main lobe and a first side-lobe of switching frequency.

• Journal of Korean Society of societal Security
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• v.4 no.2
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• pp.29-40
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• 2011

The objective of this paper is to develop an intelligent decision support system that is able to advise disaster countermeasures and degree of incidents on the basis of the collected and analyzed signs of disasters. The concepts derived from ontology, text mining and case-based reasoning are adapted to design the system. The functions of this system include term-document matrix, frequency normalization, confidency, association rules, and criteria for judgment. The collected qualitative data from signs of new incidents are processed by those functions and are finally compared and reasoned to past similar disaster cases. The system provides the varying degrees of how dangerous the new signs of disasters are and the few countermeasures to the disaster for the manager of disaster management. The system will be helpful for the decision-maker to make a judgment about how much dangerous the signs of disaster are and to carry out specific kinds of countermeasures on the disaster in advance. As a result, the disaster will be prevented.

• Journal of Convergence for Information Technology
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• v.7 no.2
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• pp.53-58
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• 2017

This paper describes the design of a simulator for analyzing the accuracy of a correlative interferometer(CI) direction finder. CI direction finder is robust to noise, so it is often used in aircraft or ships where complex antenna installation is required, and the direction finding accuracy is very high. When the radio wave is incident at a specific azimuth angle, the phase difference calculated in a noiseless environment and the phase difference measured in a real environment with noise are fused to estimate the largest correlation coefficient as the azimuth angle of the radio wave. The simulator receives RF frequency, the number of antennas, the antenna coordinates, the transmission signal intensity, the bandwidth of the receiver, the gain and the payload effect, and calculates the direction finding accuracy of 0-360 degrees azimuth and 0-60 degree elevation with 0.5 degree. accuracy.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.4
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• pp.308-315
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• 2019

In this study, numerical simulations of slamming impact pressure acting on the flat plate and wedge type models using the cartesian-grid system and Modified Marker-Density Method (MMD method) were performed and the results were examined. The flat plate and wedge type models were selected as target objects, the turbulence characteristics were considered by applying the Sub-Grid Scale (SGS) turbulence model. Through this study, how the pressure acting on the target objects according to the incident angle influences the slamming impact pressure was examined and the results were compared with the flow characteristics of other experimental results. Also, the degree of slamming impact pressure is evaluated with respect to the cartesian-grid system and MMD method, which is easy to use and has a high degree of calculation for free surface.

• Journal of Preventive Medicine and Public Health
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• v.36 no.3
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• pp.279-288
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• 2003

Objectives : Evidence for an effect of rerroductive factors on colorectal carcinogenesis is not yet consistent. Little research has been conducted to investigate whether reproductive factors were associated with colorectal adenomas that are the precursors of colorecta1 cancer, We evaluated the relationships between reproductive factors and the degree of dysplasia of the colorectal adenoma and cancer as colorectal adenoma-carcinoma sequence. Methods : For this study, 241 adenoma cases with histopathologically confirmed incident colorectal adenoma, 76 cancer cases with colorectal cancer and 1677 controls were collected from Our Lady of Mercy Hospital, The Catholic University of Korea, during 1994-1999. Before colonoscopy, information on demographic characteristics, reproductive factors, life style habits and dietary intake were obtained by interviewed questionnaire. Adjusted OR and 95% CI were estimated by using polytomous logistic regression model, Potential confounders that were selected based on the goodness of fit Statistics and interaction between risk factors were considered in this adjustment. The Wald statistic was calculated to test the heterogeneity of the odds ratios for each case. Results .: Postmenopausal women with natural menopause were found to be positively associated with the risk of mild dysplasia adenoma (multivariate-adjusted OR : 2.59, 95% CI=1.1-0.2). Parity was found to be negatively associated with the risk of colorectal lancer (age-adjusted OR : 0.40, 95% CI=0.2-0.9), but did not significantly decrease the risk of colorectal cancer (multivariate-adjusted OR : 0.95, 95% CI=0.3-2.9). Me associations were seen between a9e at menarche, breast feeding, induced abortion, oral contraceptive use, menopausal types, menopausal age or hormone replacement therapy (HRT and the degree of dysplasia of the colorectal adenoma and cancer. However, none of these associations differed' significantly between the degree of dysplasia of the colorectal adenoma and cancer. Conclusions : These findings suggest that postmenopausal women with natural menopause may experience increased risk of mild dysplasia adenorna among colorectal adenoma-carcinoma sequence.

• Geomechanics and Engineering
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• v.22 no.2
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• pp.187-196
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• 2020

The changeable stress environment directly affect the propagation law of a stress wave. Stress wave propagation tests in sandstone with different axial stresses were carried using a modified split Hopkinson Pressure bar (SHPB) assuming the sandstone has a uniform pore distribution. Then the waveform and stress wave energy dissipation were analyzed. The results show that the stress wave exhibits the double peak phenomenon. With increasing axial stress, the intensity difference decreases exponentially and experiences first a dramatic decrease and then gentle development. The demarcation stress is σ/σ_c=30%, indicating that the closer to the incident end, the faster the intensity difference attenuates. Under the same axial stress, the intensity difference decreases linearly with propagation distance and its attenuation intensity factor displays a quadratic function with axial stress. With increasing propagation distance, the time difference decays linearly and its delay coefficient reflects the damage degree. The stress wave energy attenuates exponentially with propagation distance, and the relations between attenuation rate, attenuation coefficient and axial stress can be represented by the quadratic function.