• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.4
• /
• pp.342-354
• /
• 2008

Some statistical characteristics of deepwater waves along the Korean coast have been investigated using various sources of wave measurement and hindcasting data. For very large waves comparable to design waves, it is recommended to use the average value of the empirical formulas proposed by Shore Protection Manual in 1977 and by Goda in 2003 for the relation between significant wave height and period. The standard deviation of significant wave periods non-dimensionalized with respect to the mean value for a certain significant wave height varies between 0.04 and 0.21 with a typical value of 0.1 depending upon different regions and different ranges of significant wave heights. The mean and standard deviation of the principal deepwater wave direction are presented at the 106 coastal grid points along the Korean coast. For relatively large waves, the probability density function of the directional spreading parameter $s_{max}$ is expressed as a lognormal distribution. The most suitable frequency spectrum in the Korean coast is the TMA spectrum. The probability density function of the peak enhancement factor $\gamma$ is also expressed as a lognormal distribution, with its mean value of 2.94, which is close to the value in the North Sea.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.5
• /
• pp.465-475
• /
• 2020

I-D-F curves were induced by Box-Cox transformation using rainfall data from five major cities in Korea: Seoul, Busan, Daegu, Daejeon, and Gwangju, as well as from Sancheong (South Gyeongsang province) and Yeongcheon (North Gyeongsang province) stations. The practicality of the Box-Cox transformation is more scalable than the traditional method of frequency analysis in terms of applicability because it is available even if the analysis data are insufficient to perform general frequency analysis and do not produce an appropriate probability density function. For the case in which rainfall data for the entire period (10-1440 minutes) and short-term period (20, 30, 40, 50 minutes) at the foregoing 7 stations are omitted, there was a relative error of -23.0 % to 14.7 % at a duration of 10 to 60 minutes below the 100-year frequency. Accordingly, rainfall analysis requires inducing I-D-F curves, including for the short term (20, 30, 40, 50 minutes), and if rainfall data are omitted for the short term (20, 30, 40, 50 minutes), it is necessary to increase the existing margin rate depending on the point in order to ensure the safe design of small-scale hydraulic structures.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.11
• /
• pp.1-9
• /
• 2010

As the process technology scales down, an interconnection has became a major performance constraint for multi-core processors. Recently, in order to mitigate the performance bottleneck of the interconnection for multi-core processors, a 3D integration technique has drawn quite attention. The 3D integrated multi-core processor has advantage for reducing global wire length, resulting in a performance improvement. However, it causes serious thermal problems due to increased power density. For this reason, to design efficient 3D multi-core processors, thermal-aware design techniques should be considered. In this paper, we analyze the temperature on the 3D multi-core processors in function unit level through various experiments. We also present temperature characteristics by varying application features, cooling characteristics, and frequency levels on 3D multi-core processors. According to our experimental results, following two rules should be obeyed for thermal-aware 3D processor design. First, to optimize the thermal profile of cores, the core with higher cooling efficiency should be clocked at a higher frequency. Second, to lower the temperature of cores, a workload with higher thermal impact should be assigned to the core with higher cooling efficiency.

• Journal of Bio-Environment Control
• /
• v.1 no.1
• /
• pp.1-13
• /
• 1992

This study was attemped to provide some fundamental data for the safety structural design of biological production facility. Wind speed and snow depth according to recurrence intervals for design load estimation were calculated by frequency analysis using the weather data of 60 stations in Korea. The following results were obtained : 1. Type-I extremal distribution was selected for the probability density function of yearly maximum wind speed and snow depth and result of Chi-square goodness of fit showed highly significance at most regions. 2. Design frequency factors for given number of samples and recurrence intervals were calculated, and also design wind speed and snow depth as shown in Table 5-Table 6 and Fig.3-Fig.4 were derived. 3. About 46.4% of the winds having maximum wind speed at every station was analyzed to be same direction, and the consideration of this fact may improve the structural safety. 4. Considering wind speed and snow depth, protected cultivation is very difficult in Ullungdo and the Youngdong districts, and strong structural design is needed in the Chungnam and Junbuk west seaside against snow depth and the west-south seaside against wind speed in Korea.

• Journal of Korea Water Resources Association
• /
• v.49 no.5
• /
• pp.411-422
• /
• 2016

Rainfall-runoff modeling in conjunction with rainfall frequency analysis has been widely used for estimating design floods in South Korea. However, uncertainties associated with underlying distribution and sampling error have not been properly addressed. This study applied a Bayesian method to quantify the uncertainties in the rainfall frequency analysis along with Gumbel distribution. For a purpose of comparison, a probability weighted moment (PWM) was employed to estimate confidence interval. The uncertainties associated with design rainfalls were quantitatively assessed using both Bayesian and PWM methods. The results showed that the uncertainty ranges with PWM are larger than those with Bayesian approach. In addition, the Bayesian approach was able to effectively represent asymmetric feature of underlying distribution; whereas the PWM resulted in symmetric confidence interval due to the normal approximation. The use of long period data provided better results leading to the reduction of uncertainty in both methods, and the Bayesian approach showed better performance in terms of the reduction of the uncertainty.

• The Journal of the Petrological Society of Korea
• /
• v.24 no.3
• /
• pp.165-180
• /
• 2015

Jurassic granite from Geochang was analysed with respect to the characteristics of the rock cleavage. The phases of distribution of microcracks were well evidenced from the enlarged photomicrographs(${\times}6.7$) of the thin section. In this study, the length - cumulative frequency diagrams were used for expressing the distribution characteristics of microcrack. The diagrams for the six directions were arranged in the magnitude of density(${\rho}$). These diagrams show an order of H2 < H1 < G2 < G1 < R2 < R1 from the related chart. Among six diagrams, the diagram for hardway 2(H2) occupies the lowermost region on the left. On the contrary, the diagram for rift 1(R1) occupies the uppermost region on the right. Curve patterns of the two diagrams change from uniform to exponential distribution type in accordance with the increased density. The overall distribution characteristics of the diagrams were well evidenced from the magnitude of the exponent(${\lambda}$) and length of line oa related to the exponential straight line. The magnitude of exponent governing the values of slope(${\theta}$) is inversely proportional to the values of microcrack parameters such as number(N), length(L) and density. On the contrary, length of line oa is directly proportional to the values of the above three parameters. Above microcrack parameters related to the order of arrangement of diagrams show an order of hardway(H1 + H2) < grain(G1 + G2) < rift(R1 + R2). The distribution characteristics of progressive variation are found among the six diagrams. The order of arrangement of the diagrams indicates a relative magnitude of the rock cleavage. Meanwhile, the parameters such as slope, exponent, density and length of line oa were arranged in an order of H2 < H1 < G2 < G1 < R2 < R1. The variation curves of a smooth quadratic function are shown from the related chart. From the correlation chart between density and the above parameters, a common regularity following power-law correlation function was derived. Finally, the analysis for the rock cleavage was conducted through the combination between the diagram and microcrack parameter. This type of combination contribute to the progressivity in evaluation for the rock cleavage.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.2
• /
• pp.120-127
• /
• 2012

Exploratory data analysis was carried out by using the long-term wave climate data in Sokcho coastal zone. The main features found in this study are as follows. The coefficient of variations on the wave height and period are about 0.11 and 0.02, respectively. It also shows that the annual components of the wave height and period are dominant and their amplitudes are 0.24 m and 0.56 seconds, respectively. The amount of intra-annual variation range is about two times greater than that of the inter-annual variation range. The distribution shapes of the wave data are very similar to the log-normal and GEV(generalized extreme value) functions. However, the goodness-of-fit tests based on the KS test show as "rejected" for all suggested density functions. Then, the structure of the timeseries wave height data is roughly estimated as AR(3) model. Based on the wave duration results, it is clearly shown that the continuous and maximum duration is decreased as a power function shape and the total duration is exponentially decreased. Meanwhile, the environment of the Sokcho coastal zone is classified as a wave-dominated environment.

• The Journal of the Acoustical Society of Korea
• /
• v.23 no.1
• /
• pp.8-16
• /
• 2004

An inversion method is presented for the determination of the compressional wave speed, compressional wave attenuation, thickness of the sediment layer and density as a function of depth for a horizontally stratified ocean bottom. An experiment for estimating those properties was conducted in the shallow water of South Sea in Korea. In the experiment, a light bulb implosion and the propagating sound were measured using a VLA (vertical line array). As a method for estimating the geoacoustic properties, a coherent broadband matched field processing combined with Genetic Algorithm was employed. When a time-dependent signal is very short, the Fourier transform results are not accurate, since the frequency components are not locatable in time and the windowed Fourier transform is limited by the length of the window. However, it is possible to do this using the wavelet transform a transform that yields a time-frequency representation of a signal. In this study, this transform is used to identify and extract the acoustic components from multipath time series. The inversion is formulated as an optimization problem which maximizes the cost function defined as a normalized correlation between the measured and modeled signals in the wavelet transform coefficient vector. The experiments and procedures for deploying the light bulbs and the coherent broadband inversion method are described, and the estimated geoacoustic profile in the vicinity of the VLA site is presented.

• Journal of agricultural medicine and community health
• /
• v.16 no.2
• /
• pp.165-171
• /
• 1991

Two patients with confirmed cerebral cysticercosis were treated with Albendazole(Zentel$^{(R)}$) at a daily dose of 1.200mg t.i.d. for 14 consecutive days and evaluated for tolerance and therapeutic effects. First case was 29 year old male, who had experience of 4 times of grand mal seizures during 1 year period before administration in Korea University Hospital. His chief complaints were seizure and moderate degree headache. He also had 4 subcutaneous nodules on the thorax, right and left upper arms. Among them one nodule was biopsied and confirmed microscopically as Cysticercus cellulosae hominis. Computed tomography of the brain showed four round low density lesions in right postero-frontal area, sylvian area, intra-occipital area and left parietal area. Second case was 48 year old male, who also had experience of seizures at 3 years, 5 months and 3 months before administration. In this case, no subcutaneous nodules and no headaches were noted. Brain CT showed four round low density lesions in right postero-parietal area and temporo-parietal area, and left temporo-parietal and parietal area. Serum antibody against cystic fluid antigen was detected by ELISA in both cases. The efficacy of the treatment of cerebral cysticercosis was assessed by the frequency of convulsions after treatment for 22 months follow-up. by the disappearance of the densities in cystic lesions at brain CT for 6 months follow-up, and disappearance of subcutaneous nodules, headache and so on. As the results, all low density lesions in both cases were disappeared in films of brain CT, and 4 nodules in first case were also disappeared. No more seizure and complain of headache occurred during the last 22 months after treatment in both cases. Post-treatment complete blood count and liver function test revealed no remarkable change compared to pre-treatment test. In the nations of Latin America, the physicians do not initially recommended the simultaneous administrations of steroids, reserving them only for patients whom the adverse reactions such as severe headache and/or seizures are occurred. According to them, in most patients these symptoms are controlled with aspirin and symptomatic drugs. But our experience using praziquantel is different, and most cerebral cysticercosis patients who takes PZQ had complaint of severe headache and sometimes seizure. So we simultaneously used dexamethasone as 6mg q.i.d. for 14 consecutive days and 6 days tapering thereafter in both cases for prevention of reactions produced by the host in response to the deaths of the parasites. As the conclusion, albendazole is effective in patients who presented cerebral cysticercosis and albendazole may help in the control of cysticercosis.

• Journal of Korea Water Resources Association
• /
• v.48 no.7
• /
• pp.567-579
• /
• 2015

This study performed the non-stationary flood frequency analysis considering time-varying parameters of a probability density function. Also, return period and risk under non-stationary condition were estimated. A stationary model and three non-stationary models using Generalized Extreme Value(GEV) were developed. The only location parameter was assumed as time-varying parameter in the first model. In second model, the only scale parameter was assumed as time-varying parameter. Finally, the both parameters were assumed as time varying parameter in the last model. Relative likelihood ratio test and Akaike information criterion were used to select appropriate model. The suggested procedure in this study was applied to eight multipurpose dams in South Korea. Using relative likelihood ratio test and Akaike information criterion it is shown that the inflow into the Hapcheon dam and the Seomjingang dam were suitable for non-stationary GEV model but the other six dams were suitable for stationary GEV model. Also, it is shown that the estimated return period under non-stationary condition was shorter than those estimated under stationary condition.