• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.42-42
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• 2019

유량조절을 위한 자동수문은 설정된 관리수위 이하에서는 수문이 개방되지 않으며, 유량이 증가하여 관리수위 이상이 되면 수문이 개방되어 방류를 시작하여 일정 수위를 유지하는 것을 의미한다. 자동수문의 운영 중 수문의 거동과 자동 개폐 시점을 예측하는 것은 정밀한 수문 설계를 위해 매우 중요하다. 수문 하단으로 흐름이 발생하면 수문 선단을 포함한 주변에서의 압력 차이로 인한 동수압 하중이 발생하고 진동을 유발, 수문 개방을 억제하는 하향력 등의 효과로 수문 운영에 큰 영향을 미친다. 본 연구에서는 부력식 수문의 모형실험을 통하여 정수압 상태의 부력 이론에 의한 수문 개방률과 측정에 의한 수문 개방률을 비교하였으며, 이론과 측정 수문 개방고의 차이를 하향력에 의한 효과임을 확인하였다. 부력식 수문의 하향력을 검토하기 위해 기존 이론식을 이용한 결과, 이론식은 부력식 수문에 적용하기 어려운 것으로 나타났다. 따라서, 기존 이론식을 이용하여 부력식 수문의 하향계수 산정을 위한 매개변수 관계식을 개방률을 이용하여 제시하였다. 제시된 매개변수 관계식의 결정계수는 0.721, 수정된 결졍계수는 0.690으로 나타났다. 부력식 수문의 형상비에 따른 하향력을 검토하기 위해서 수치모의를 수행하였다. 모형실험에서 측정된 자료와 수치모형 ANSYS-Fluent의 사용성을 검증하였고, 부력식 수문의 형상비를 0.24, 0.49, 0.69, 0.89, 1.09로 총 5가지로 설정하여 하향계수와 하향력을 분석하였다. 부력식 수문의 하향계수와 하향력 검토는 부력체, 스커트로 구분하여 분석을 수행하였다. 하향계수 분석결과, 하향계수는 개방률이 증가함에 따라 감소하였으며 하향계수가 부력체 부분에서는 0.465~1.542, 스커트 부분에서는 0.058~1.148의 범위로 나타났다. 하향력 분석결과, 하향력은 개방률 0.300 이하에서는 개방률이 증가함에 따라 하향력은 증가하였나 개방율 0.300 초과하면서부터 개방률이 증가함에 따라 하향력이 감소하는 것으로 나타났다. 또한 부력체 부분에서는 형상비가 증가함에 따라 하향력이 감소하였으나, 스커트 부분에서는 형상비가 증가함에 따라 하향력이 증가하였다. 이는 형상비가 증가함에 따라 스커트 부분의 면적이 증가하기 때문이다. 부력식 수문의 전체적인 하향력을 계산한 결과, 부력식 수문의 하향력은 0.002~0.015 kN의 범위를 가지며 형상비가 증가함에 따라 부력식 수문에 발생하는 하향력은 증가하는 것으로 나타났다.

• Journal of Animal Science and Technology
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• v.46 no.5
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• pp.743-752
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• 2004

This experiment was conducted to investigate the effect of filtered water with silicate minerals on growth performance and pork quality. A total of 64 pigs were allotted at 37.95 kg body weight to 4 treatments in a randomized complete block(RCB) design. Each treatment had 4 replicates and treatments were I) Con(basaI diet). 2) Si-I(consumed silicate mineral filtered water and silicate mineral additive during 4 weeks before market weight), 3) Si-Il( consumed silicate mineral filtered water and silicate mineral additive during 8 weeks before market weight) and 4) Si-I1I(consumed silicate mineral filtered water and silicate mineral additive during 12 weeks before market weight). Silicate complex was added at 0.8% to basal diet. All pigs were allowed to feed and water ad libitum for 12 weeks. During last 4 weeks, average daily gain(ADG) in Si-Il and Si-III group was higher than that in Si-I group(P < 0.05). However overall experimental period, there were no significant differences in growth performance among all treatments. Acceptability of cooked pork at 7th day after slaughter in Si-lII group was higher than that in Con group(P < 0.05). The value of pH of fresh pork at 6 hours after slaughter was lower in Si-I1I group than that in Con group(P < 0.05). TBA values of fresh pork at 14th day after slaughter were lower in Si-II and Si-III groups than Con group(P < 0.05). These results demonstrated that pork quality could be improved when pigs consumed both silicate mineral and silicate mineral filtered water. However, growth performance was not improved by the consumption of silicate mineral filtered water and silicate mineral.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1218-1226
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• 2008

With the development of semiconductor integrated technology and with the increasing use of multimedia functions in computer, more functions have been implemented as hardware. Nowadays, most microprocessors beyond 32 bits generally implement an integer multiplier as hardware. However, as for a divider, only specific microprocessor implements traditional SRT algorithm as hardware due to complexity of implementation and slow speed. This paper suggested an algorithm that uses a multiplier, 'w bit $\times$ w bit = 2w bit', to process $\frac{N}{D}$ integer division. That is, the reciprocal number D is first calculated, and then multiply dividend N to process integer division. In this paper, when the divisor D is '$D=0.d{\times}2^L$, 0.5 < 0.d < 1.0', approximate value of ' $\frac{1}{D}$', '$1.g{\times}2^{-L}$', which satisfies ' $0.d{\times}1.g=1+e$, $e<2^{-w}$', is defined as over reciprocal number and then an algorithm for over reciprocal number is suggested. This algorithm multiplies over reciprocal number '$01.g{\times}2^{-L}$' by dividend N to process $\frac{N}{D}$ integer division. The algorithm suggested in this paper doesn't require additional revision, because it can calculate correct reciprocal number. In addition, this algorithm uses only multiplier, so additional hardware for division is not required to implement microprocessor. Also, it shows faster speed than the conventional SRT algorithm and performs operation by word unit, accordingly it is more suitable to make compiler than the existing division algorithm. In conclusion, results from this study could be used widely for implementation SOC(System on Chip) and etc. which has been restricted to microprocessor and size of the hardware.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.27-39
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• 2012

This research is to propose the reinforcing method and design code for the lateral behaviors of the abutment displacement induced from the rainfall infiltration on high landfill slope. First, to make the proper numerical analysis, in-situ soil (weathered granite soil) was taken, and the variance of strength parameters according to water content variance was examined by undrained direct shear test, furthermore, other soil parameters were calculated from the standard penetration test such as elastic modulus and Poisson's ratio etc,. Those parameters were used to calculate the lateral behavior of abutment by finite element method and the member force of pile in high landfill slope according to rainfall infiltration . From the results, the shoe displacement on abutment was calculated as 8.98cm, which is 3 times bigger than the allowable displacement, 3cm. To reinforce it, several reinforcing methods were selected and analyzed such as reinforced retaining wall, soil surcharge, pile reinforcing (5m enlargement, 3-line arrangement, 5m enlargement and 3-line arrangement). In case of 5m enlarged and 3-line arrangement piles, the lateral behavior of shoe showed lower value(2.26 cm) than allowable displacement.

• The Korean Journal of Ecology
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• v.25 no.5
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• pp.359-364
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• 2002

This study was conducted to examine the seasonal pattern of N and P uptake by reeds (Phragmites australis) planted in newly constructed Shihwa tidal freshwater marshes. Reed and soil samples were collected from the wetland periodically from June 2000 to May 2002. Reed samples were analyzed for dry weight and content of N and P Soil organic matter content and salinity were also determined. Dry matter content of reed increased during the growing season but decreased in the fall and winter. However, this seasonal pattern was not so evident in the second year. In particular, throughout the measurement period, dry matter content of reed was lowest at a site showing high soil salinity. Regression analyses between dry matter content of reed and soil EC(1:5) suggested that dry matter content per unit square meter would decrease by 1.5 kg with every 1 dS m/sup -1/ increase in soil EC(1:5). The amount of N and P assimilated by reed significantly decreased from the fall and was lowest in the spring. Net decrease in N content from reed during the fall and next spring was calculated as 34.5 and 24.6 g m/sup -2/ in the first and second years, respectively, while the corresponding P loss was 4.0 and 1.8 g m/sup -2/. Soil organic mailer content increased in the fall and winter, but decreased in the spring and summer. The results of this study suggested that the removal of N and P by reed would be considerable during the growing season but the nutrients taken up by reeds would return as detritus to the marshes in the fall and winter. Based on the results of the study, therefore, the harvest of the reed at the latter part of the growth would be recommended to prevent further water quality degradation. However, the long-term effects of reed harvest needs further study.

• Journal of Elementary Mathematics Education in Korea
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• v.13 no.2
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• pp.211-229
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• 2009

The purpose of this study is analysis of to investigate relation proportion problem of mathematics textbooks of 7th curriculum to proportional reasoning(relative thinking, unitizing, partitioning, ratio sense, quantitative and change, rational number) of Lamon's proposal at sixth grade students. For this study, I develop two test papers; one is for proportion problem of mathematics textbooks test paper and the other is for proportional reasoning test paper which is devided in 6 by Lamon. I test it with 2 group of sixth graders who lived in different region. After that I analysis their correlation. The result of this study is following. At proportion problem of mathematics textbooks test, the mean score is 68.7 point and the score of this test is lower than that of another regular tests. The percentage of correct answers is high if the problem can be solved by proportional expression and the expression is in constant proportion. But the percentage of correct answers is low, if it is hard to student to know that the problem can be expressed with proportional expression and the expression is not in constant proportion. At proportion reasoning test, the highest percentage of correct answers is 73.7% at ratio sense province and the lowest percentage of that is 16.2% at quantitative and change province between 6 province. The Pearson correlation analysis shows that proportion problem of mathematics textbooks test and proportion reasoning test has correlation in 5% significance level between them. It means that if a student can solve more proportion problem of mathematics textbooks then he can solve more proportional reasoning problem, and he have same ability in reverse order. In detail, the problem solving ability level difference between students are small if they met similar problem in mathematics text book, and if they didn't met similar problem before then the differences are getting bigger.

• Journal of Navigation and Port Research
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• v.34 no.1
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• pp.15-19
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• 2010

Recently, the wireless LAN system is rapidly growing because of its convenience of high speed communication. However, the wireless LAN systems at indoor places occur multi-propagation path by reflected waves from walls, ceilings, floors, and desks. Multipath problems cause transmission errors and degradation of communication speed. These problems can be solved by using EM wave absorbers. In this paper, we analyzed property of Graphite and derived the optimum ratio of Graphite: CPE to develop EM wave absorber for the wireless LAN system. First, we fabricated several samples in different composition ratios of Graphite and CPE, and then measured the reflection coefficient of each samples. Material constants of permittivity and permeability were calculated using the measured data and designed EM wave absorber. Secondly, the EM wave absorber was fabricated and tested on the base of the simulation data. As a result, it showed that the EM wave absorber in 1.7 mm thickness with the ratio of Graphite: CPE=50:50 wt.% has excellent absorption ability more than 27 dB at 5.2 GHz.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.3
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• pp.114-123
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• 2016

The effective feature extraction method for unmanned aerial vehicle (UAV) detection is proposed and verified in this paper. The UAV engine sound is harmonic complex tone whose frequency ratio is integer and its variation is continuous in time. Using these characteristic, we propose the feature vector composed of a mean and standard deviation of difference value between fundamental frequency with 1st overtone as well as mean variation of their frequency. It was revealed by simulation that the suggested feature vector has excellent discrimination in target signal identification from various interfering signals including frequency variation with time. By comparing Fisher scores, three features based on frequency show outstanding discrimination of measured UAV signals with low signal to noise ratio (SNR). Detection performance with simulated interference signal is compared by MFCC by using ELM classifier and the suggested feature vector shows 37.6% of performance improvement As the SNR increases with time, the proposed feature can detect the target signal ahead of MFCC that needs 4.5 dB higher signal power to detect the target.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.107-115
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• 2023

High turbidity in source water can have adverse effects on water treatment plant operations and aquatic ecosystems, necessitating turbidity management. Consequently, research aimed at predicting river turbidity continues. This study developed a multi-class classification model for prediction of turbidity using LightGBM (Light Gradient Boosting Machine), a representative ensemble machine learning algorithm. The model utilized data that was classified into four classes ranging from 1 to 4 based on turbidity, from low to high. The number of input data points used for analysis varied among classes, with 945, 763, 95, and 25 data points for classes 1 to 4, respectively. The developed model exhibited precisions of 0.85, 0.71, 0.26, and 0.30, as well as recalls of 0.82, 0.76, 0.19, and 0.60 for classes 1 to 4, respectively. The model tended to perform less effectively in the minority classes due to the limited data available for these classes. To address data imbalance, the SMOTE (Synthetic Minority Over-sampling Technique) algorithm was applied, resulting in improved model performance. For classes 1 to 4, the Precision and Recall of the improved model were 0.88, 0.71, 0.26, 0.25 and 0.79, 0.76, 0.38, 0.60, respectively. This demonstrated that alleviating data imbalance led to a significant enhancement in Recall of the model. Furthermore, to analyze the impact of differences in input data composition addressing the input data imbalance, input data was constructed with various ratios for each class, and the model performances were compared. The results indicate that an appropriate composition ratio for model input data improves the performance of the machine learning model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2C
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• pp.85-93
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• 2010

The shear stiffness has become an important design parameter to understand the soil behavior. In particular, the elastic moduli and void ratio has been considered as important parameters for the design of the geotechnical structures. The objective of this paper is the development of the penetration type Field Velocity and Resistivity Probe (FVRP) which is able to assess the elastic moduli and void ratio based on the elastic wave velocities and electrical resistivity. The elastic waves including the compressional and shear wave are measured by piezo disk elements and bender elements. And the electrical resistivity is measured by the resistivity probe, which is manufactured and installed at the tip of the FVRP. The penetration tests are carried out in calibration chamber and field. In the laboratory calibration chamber test, after the sand-clay slurry mixtures are prepared and consolidated. The FVRP is progressively penetrated and the data are measured at each 1 cm. The field experiment is also carried out in the southern part of Korea Peninsular. Data gathering is performed in the depth of 6~20 m at each 10 cm. The elastic moduli and void ratio are estimated based on the analytical and empirical solutions by using the elastic wave velocities and electrical resistivity measured in the chamber and field. The void ratios based on the elastic wave velocities and the electrical resistivity are similar to the volume based void ratio. This study suggests that the FVRP, which evaluates the elastic wave velocities and the electrical resistivity, may be a useful instrument for assessing the elastic moduli and void ratio in soft soils.