• 한국지진공학회논문집
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• 제17권1호
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• pp.21-31
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• 2013

In this study, dynamic characteristics and seismic capacity of the nuclear power plant piping system are evaluated by model test results using multi-platform shake table. The model is 21.2 m long and consists of straight pipes, elbows, and reducers. The stainless steel pipe diameters are 60.3 mm (2 in.) and 88.9 mm (3 in.) and the system was assembled in accordance with ASME code criteria. The dynamic characteristics such as natural frequency, damping and acceleration responses of the piping system were estimated using the measured acceleration, displacement and strain data. The natural frequencies of the specimen were not changed significantly before and after the testing and the failure and leakage of the piping system was not observed until the final excitation. The damping ratio was estimated in the range of 3.13 ~ 4.98 % and it is found that the allowable stress(345 MPa) according to ASME criteria is 2.5 times larger than the measured maximum stress (138 MPa) of the piping system even under the maximum excitation level of this test.

• Structural Engineering and Mechanics
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• 제74권5호
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• pp.711-722
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• 2020

In this study, on-site testing was carried out to investigate the vibration serviceability of a composite steel-bar truss slab with steel girder system. Impulse excitations (heel-drop and jumping) and steady-state motion (walking and running) were performed to capture the primary vibration parameters (natural frequency and damping ratio) and distribution of peak acceleration. The composite floor possesses low frequency (<8.3Hz) and damping ratio (<2.47%). Based on experimental, theoretical, and numerical analyses on fundamental natural frequency, the boundary condition of SCSS (i.e., three edges simply supported and one edge clamped) is deemed more comparable substitutive for the investigated composite floor. Walking and running excitations by one person (single excitation) were considered to evaluate the vibration serviceability of the composite floor. The measured acceleration results show a satisfactory vibration perceptibility. For design convenience and safety, a crest factor β_rp describing the ratio of peak acceleration to root-mean-square acceleration induced from the walking and running excitations is proposed. The comparisons of the modal parameters determined by walking and running tests reveal the interaction effect between the human excitation and the composite floor.

• Geomechanics and Engineering
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• 제15권1호
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• pp.677-686
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• 2018

Aimed at serious casing damage problem during the process of oilfield development by injecting water, based on seepage mechanics, fluid mechanics and the theory of rock mechanics, the multi-physics coupling theory was also taken into account, the mathematical model for production of petroleum with water flooding was established, and the method to solve the coupling model was presented by combination of Abaqus and Eclipse software. The Q9G3 block in Jibei oilfield was taken for instance, the well log data and geological survey data were employed to build the numerical model of Q9G3 block, the method established above was applied to simulate the evolution of seepage and stress. The production data was imported into the model to conduct the history match work of the model, and the fitting accuracy of the model was quite good. The main mechanism of casing damage of the block was analyzed, and some wells with probable casing damage problem were pointed out, the displacement of the well wall matched very well with testing data of the filed. Finally, according to the simulation results, some useful measures for preventing casing damage in Jibei oilfield was proposed.

• 한국작물학회지
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• 제44권1호
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• pp.78-85
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• 1999

To investigate kernel hardness, a compression test which is widely used to measure the hardness of individual kernels as a physical testing method was made simultaneously with the measurement of friabilin (15KDa) which is strongly associated with kernel hardness and was recently developed as a biochemical marker for evaluating kernel hardness in 79 Korean wheat varieties and experimental lines. With the scattered diagram based on the principal component analysis from the parameters of the compression test, 79 Korean wheat varieties were classified into three groups based on the principal component analysis. Since conventional methods required large amount of flour samples for analysis of friabilin due to the relatively small amount of friabilin in wheat kernels, those methods had limitations for quality prediction in wheat breeding programs. An extraction of friabilin from the starch of a single kernel through cesium chloride gradient centrifugation was successful in this experiment. Among 79 Korean wheat varieties and experimental lines 50 lines (63.3%) exhibited a friabilin band and 29 lines (36.7%) did not show a friabilin band. In this study, lines that contained high maximum force and the lower ratio of minimum force to maximum force showed the absence of the friabilin band. Identification of friabilin, which is the product of a major gene, could be applied in the screening procedures of kernel hardness. The single kernel analysis system for friabilin was found to be an easy, simple and effective screening method for early generation materials in a wheat breeding program for quality improvement.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.127-130
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• 2005

The feasibility of stimulating in situ aerobic cometabolic activity of indigenous microorganisms was investigated in a trichloroethene(TCE)-contaminated aquifer, A series of single-well natural drift tests (SWNDT) was conducted by injecting site groundwater amended with a bromide tracer and combinations of toluene, oxygen, nitrate, ethylene and TCE into an existing monitoring well and by sampling the same well over time. Transformation of ethylene, a surrogate of overall TCE transformation activity, was also observed, and its transformation results in the production of ethylene oxide, suggesting that some tolune-oxidizing microorganisms stimulated may express a monooxygenase enzymes. Also in situ transformation of TCE was confirmed by dilution-adjusted data analysis developed in this study. These results indicate that, in this environment, toluene and oxygen additions stimulated the growth and aerobic cometabolic activity of indigenous microorganisms expressing monooxygenase enzymes and that these are responsible for observed toluene utilization and cometabolism of ethylene and TCE. The simple, low-cost field test method provides an effective method for conducting rapid field assessments and pilot testing of aerobic cometabolism of TCE, which has previously hindered application of this technology to groundwater remediation.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.592-597
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• 2005

Biogas is widely accepted as one of renewable energy. Raw biogas can be used in internal combustion engines either spark ignition or diesel engines. Since the gas has relatively low calorific values, engine power also is lower than rated power values. Modified engines or biogas-specific engines have been utilized in order to increase efficiency. Recently, gas engine/generators are provided for various purposes. They are mostly for LPG or natural gas. When biogas is fueled to the gas engines, de-rating is inevitable due to its lower calorific values. Meanwhile, massively produced commercial gas engines are more competitive in terms of initial investment for engines, compared to biogas-specific engines. Then, the characteristics of the commercial engine and power generation should be understood for better operation. A 5kW gas engine/generator(natural gas) was tested for determining an allowable maximum concentration of $CO_2$ in synthetic biogas, with respect to engine stating, power generation. Experimental results indicated that about 65% of methane concentration is required to start the gas engine. At this condition, the power generated was about 3 kW. It is about 60% of the nominal power, which is similar to the ratio of calorific values.

• Journal of the Korean Wood Science and Technology
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• 제24권1호
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• pp.11-16
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• 1996

The purpose of this paper is to present a summary of assignment design values according to domestic softwood structural lumber grading rules. Allowable stresses for visually graded lumber were determined from basic data on small. clear specimens. The data corrected for variability such as natural defects and other factors. The procedure adopted by Japan was used for assigning allowable design values. Strength ratios in relation to each defect were taken from ASTM D 245-81. Korean pine(Pinus koraiensis S. et Z.), Korean red pine(Pinus densiflora S. et Z.), Japanese larch(Larix leptolepis Gordon) and Needle fir(Abies holophylla Max) were applied to this study. The calculated allowable stresses were same in Korean pine and Korean red pine. These values were highest in Japanese larch lowest in Needle fir. So, it is desirable for these species to be classified into different catagories Species Group. However, accurate comparison in design values on lumber grading rules among U.S., Japan and Korea was somewhat difficult. And full scale testing will be necessary for accurate determination of the correction factors to setting up design values.

• 한국광학회지
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• 제16권1호
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• pp.71-78
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• 2005

대형 비구면의 측정을 위하여 자동무수차점 방식의 2매 구성 널 렌즈를 설계하였고, 제작과 정렬 오차에 따른 측정 정밀도의 한계를 이론적으로 분석해 보았다. 측정 정밀도의 한계를 결정짓는 주요한 공차 요소는 널 렌즈면의 불규칙도(irregularity)임을 확인하였으며, 불규칙도의 가공 정도에 따라 5λ/100∼4λ/1000 정도까지의 신뢰할 수 있는 측정 정밀도가 한정지어졌다. 이로써 실제의 정렬 오차 및 널 렌즈 제작오차까지 고려하여 신뢰할 수 있는 정밀도 한계를 제시할 수 있었다.

• Journal of Information Processing Systems
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• 제8권3호
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• pp.399-408
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• 2012

Hand gesture recognition is an important area of research in the field of Human Computer Interaction (HCI). The geometric attributes of the hand play an important role in hand shape reconstruction and gesture recognition. That said, fingertips are one of the important attributes for the detection of hand gestures and can provide valuable information from hand images. Many methods are available in scientific literature for fingertips detection with an open hand but very poor results are available for fingertips detection when the hand is closed. This paper presents a new method for the detection of fingertips in a closed hand using the corner detection method and an advanced edge detection algorithm. It is important to note that the skin color segmentation methodology did not work for fingertips detection in a closed hand. Thus the proposed method applied Gabor filter techniques for the detection of edges and then applied the corner detection algorithm for the detection of fingertips through the edges. To check the accuracy of the method, this method was tested on a vast number of images taken with a webcam. The method resulted in a higher accuracy rate of detections from the images. The method was further implemented on video for testing its validity on real time image capturing. These closed hand fingertips detection would help in controlling an electro-mechanical robotic hand via hand gesture in a natural way.

• 한국정보처리학회논문지
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• 제6권7호
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• pp.1825-1831
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• 1999

카오스 이론의 프랙탈 차원과 어트랙터를 이용하여 특징을 추출하여 문자인식에 적용하는 새로운 방법을 제안함으로써 기존의 혼동문자에 의한 오인식 비율을 줄이고자 하였다. 먼저 인식기에 부담을 줄이기 위해서 각 문자에 대해 특징을 조사하여 분류를 행한다. 분류된 문자에 대해 각 문자에 해당하는 Box-counting dimension, Natural Measure, Information dimension을 구하여 특징을 추출하여 인식하였다. 또한 문자의 히스토그램의 값을 이용하여 어트랙터를 구성하고 어트랙터에서 차원 값을 구한 다음 문자 자체의 차원 값과 함께 특징으로 사용하여 인식하였다. 실험 결과 전체적인 인식율의 평균은 학습 데이터에 대해서는 평균 96.03%, 미학습 데이터에 대해서는 91.74%를 나타내어 제안된 방법의 유효성을 보였다.