• Analytical Science and Technology
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• v.28 no.1
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• pp.33-39
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• 2015

CdS-QD particles are a nano-sized semiconducting crystal that emits light. Their optical properties show great potential in many areas of applications such as disease-diagnostic reagents, optical technologies, media industries and solar cells. The wavelength of emitting light depends on the particle size and thus the quality control of CdS-QD particle requires accurate determination of the size distribution. In this study, CdS-QD particles were synthesized by a simple ${\gamma}$-ray irradiation method. As a particle stabilizer polyvinyl pyrrolidone (PVP) were added. In order to determine the size and size distribution of the CdS-QD particles, sedimentation field-flow fractionation (SdFFF) was employed. Effects of carious parameters including the the flow rate, external field strength, and field programming conditions were investigated to optimize SdFFF for analysis of CdS-QD particles. The Transmission electron microscopy (TEM) analysis show the primary single particle size was ~4 nm, TEM images indicate that the primarty particles were aggregated to form secondary particles having the mean size of about 159 nm. As the concentration of the stabilizer increases, the particle size tends to decrease. Mean size determined by SdFFF, TEM, and dynamic light scattering (DLS) were 126, 159, and 152 nm, respectively. Results showed SdFFF may become a useful tool for determination of the size and its distribution of various types of inorganic particles.

• Economic and Environmental Geology
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• v.51 no.3
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• pp.223-232
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• 2018

The viscous force of fluids and the capillary force acting on the pore network of the porous media are important factors determining the immiscible displacement during geological $CO_2$ sequestration, these were directly affected by geological formation conditions and injection conditions. This study aimed to observe the migration and distribution of injected fluid and pore water, and quantitatively investigate displacement efficiency on various injection temperatures. This study aimed to perform micromodel experiments by applying n-hexane used as a proxy fluid for supercritical $CO_2$. In this study, immiscible displacement process from beginning of n-hexane injection to equilibrium of the distribution of the n-hexane and pore water was observed. The images from experiment were used to observe the displacement pattern and estimate the areal displacment efficiency of the n-hexane. For investigate the affects of the injection temperatures on the migration in macroscopic, migration of n-hexane in single pore was analyzed. The measurement revealed that the displacement efficiency at equilibrium state decreases as the temperature increases. The result from experiments indicate that the temperatures can affect the displacement pattern by changing the viscous forces and the capillary forces. The experimental results could provide important fundamental information on reservoir conditions and fluid injection conditions during geological $CO_2$ sequestration.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.474-486
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• 2010

In this paper, we propose a new method for detection moving object contour using spatial and temporal edge. In general, contour pixels of the moving object are likely present around pixels with high gradient value along the time axis and the spatial axis. Therefore, we can detect the contour of the moving objects by finding pixels which have high gradient value in the time axis and spatial axis. In this paper, we introduce a new computation method, termed as temporal edge, to compute an gradient value along the time axis for any pixel on an image. The temporal edge can be computed using two input gray images at time t and t-2 using the Sobel operator. Temporal edge is utilized to detect a candidate region of the moving object contour and then the detected candidate region is used to extract spatial edge information. The final contour of the moving object is detected using the combination of these two edge information, which are temporal edge and spatial edge, and then the post processing such as a morphological operation and a background edge removing procedure are applied to remove noise regions. The complexity of the proposed method is very low because it dose not use any background scene and high complex operation, therefore it can be applied to real-time applications. Experimental results show that the proposed method outperforms the conventional contour extraction methods in term of processing effort and a ghost effect which is occurred in the case of entropy method.

• The Journal of Engineering Geology
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• v.9 no.3
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• pp.187-206
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• 1999

A computer program to numerically predict the permeability tensor of fractured rocks is developed using information on discontinuities which Borehole Televiewer and Borehole Image Processing System (BIPS) provide. It uses orientation and thickness of a large number of discontinuities as input data, and calculates relative values of the 9 elements consisting of the permeability tensor by the formulation based on the EPM model, which regards a fractured rock as a homogeneous, anisotropic porous medium. In order to assess feasibility of the program on field sites, the numerically calculated tensor was obtained using BIPS logs and compared to the results of pumping test conducted in the boreholes of the study area. The degree of horizontal anisotropy and the direction of maximum horizontal permeability are 2.8 and $N77^{\circ}CE$, respectively, determined from the pumping test data, while 3.0 and $N63^{\circ}CE$ from the numerical analysis by the developed program. Disagreement between two analyses, especially for the principal direction of anisotropy, seems to be caused by problems in analyzing the pumping test data, in applicability of the EPM model and the cubic law, and in simplified relationship between the crack size and aperture. Aside from these problems, consideration of hydraulic parameters characterizing roughness of cracks and infilling materials seems to be required to improve feasibility of the proposed program. Three-dimensional assessment of its feasibility on field sites can be accomplished by conducting a series of cross-hole packer tests consisting of an injecting well and a monitoring well at close distance.

• Korean Journal of Health Education and Promotion
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• v.11 no.1
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• pp.43-56
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• 1994

Although the officially confirmed incidence of the acquired immune deficiency syndrome(AIDS) has remained low thus far in Korea, the progression of the pandemic has been rapid, concerned about an eventual increase in transmission. Until a vaccine or cure is found, public information and education remain an important weapon against AIDS. For the year 2000, the current WHO projection is that there will be a cumulative total of 40 million HIV infections in man, woman and children, of which more than 90％ will be in the developing countries. The incerased mortality among adults and children has raised concerns that AIDS may become so devastaing as to reverse positive population growth rates and wipe out entire population. In order to plan for the rising incidence of patient with AIDS, an assessment of AIDS-related cognition and behavior, attitude of the recognized high-risk groups is necessary. Considering that undergraduates have sexuality active and more oriented toward sexual concerns than other ages. Adolescents today are more sexually involved than in the past: The media, including films, music, and television, reinforce sexual concerns by preseating images of highly sexual adolescents. Incidence of both petting and sexual intercourse in higher and occurs at earlier ages, they are important reservoir of AIDS infection. Hence, it has become important to emymerats and describe the knowledge, attitude and behavior of them, I want.. This information will eventually guide the direction of change in public policies and education programs to meet the challenges of AIDS. The objective of this study were to identity Knowledge, Attitude, Experience of Sex and AIDS in Korea. The data were collected by survey at Korean Federation for AIDS Affairs, INC. and J university, K junior college. After October in 1993, surveyed with 507 student during their's college days in Seoul. The questionnaire was designed to provide information on sex and AIDS-related knowledge and attitudes and experience. AIDS-related knowledge was measured by using 26 questions on mode of transmission and AIDS-related attitudes were measured by 7 questions, AIDS-related experience was measured by 5 questions. There were the main dependent variables in our study, In conclusion, students during their university day need to develop AIDS-preventive education programs. Clearly, the many AIDS-prevention educational effort need to be guided by well trained health agents. Financial supports from all sectors (i.e., public and private) of our society are required to achieve that end. Further researches on AIDS-related Knowledge and Attitude and behaviors of undergraduates are needed for the development of comprehensive AIDS prevention programs.

• Restorative Dentistry and Endodontics
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• v.30 no.5
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• pp.393-401
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• 2005

The purpose of this study was to compare the canal configuration after shaping by ProTaper rotary files and ProTaper hand files in resin simulated canals. Forty resin simulated canals with a curvature of J-shape and S-shape were divided into four groups by 10 blocks each Simulated root canals in resin block were prepared by ProTaper rotary files and ProTaper hand files using a crown-down pressureless technique All simulated canals were prepared up to size $\#25$ file at end-point of preparation. Pre- and post-instrumentation images were recorded with color scanner. Assessment of canal shape was completed with an image analysis program. Measurements were made at 0, 1, 2, 3, 4, 5, 6 and 7 mm from the apex. At each level, outer canal width, inner canal width, total canal width, and amount of transportation from original axis were recorded. Instrumentation time was recorded. The data were analyzed statistically using independent t-test. The result was that ProTaper hand files cause significantly less canal transportation from original axis of canal body and maintain original canal configuration better than ProTaper rotary files, however ProTaper hand files take more shaping time.

• Korean journal of communication and information
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• v.59
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• pp.138-161
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• 2012

This study is designed to explore the function of Twitter as a campaign platform during election campaign. For exploring the function of Twitter the form of tweet, the type of information on tweet and the way of opinion expression via Twitter were discussed by content analysis. This study finds, first, that, netizens express their opoinion of candidates without foundation and with emotional reactions. Second, they showed somewhat conflictive reactions according to their supporting candidates. This study conceptualized various kinds of public as 'blindly support public,' and 'blindly opposition public' in case of Park's supporters, 'rational support public,' and 'critical opposition public' in case of Na's supporters. Third, Park's supporters debated Na candidate's attitude of debate and her appearance blindly without foundation. Na's supporters argued Park's attitude of debate and his ignorance of Seoul Metropolitan government's policy blindly without foundation. Finally, this study discussed the relationship between the political discourse according to netizens' supporting via Twitter and the results of election. Park whose supporters attacked the opposing candidate by blaming her appearance and her attitude of debate won the election. Na didn't overcome her negative images. For her Twitter functioned as a media which is spreading negative factors about her. In conclusion, Twitter as a campaign platform during election times plays a key role in discussing candidates. However, netizens need to express their opinions with foundation and the candidates have to consider negative issue management. This study highlights the importance of peripheral factors which have a decisive effect on the results of election. The results of this study is useful for building political campaign strategy by candidates.

• Korean Journal of Community Nutrition
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• v.14 no.1
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• pp.55-66
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• 2009

This study was aimed to examine nutrition knowledge, dietary attitudes, and eating habits of elementary school students and to examine if their characteristics differ by gender. Subjects were 5th and 6th graders of an elementary school (n = 317) in Seoul, and the survey was done during July 2007. Mean height, weight, BMI of subjects was 148.1 cm. 41.7 kg, 19.0, and 14.3% of subjects were categorized as the overweight/obese group. Anthropometric data were not significantly different by gender. Mean score of nutrition knowledge was 14.9 out of 20 showing moderate knowledge levels, and girls scored higher on nutrition knowledge than boys (p < 0.05). Subjects showed knowledge deficit in areas such as nutrients, food groups and specific weight control information. The percentages of correct answers regarding meals for brain function were significantly higher in girls than in boys (p < 0.05). They got nutrition information mainly from mass media and family/relatives. The mean score of dietary attitudes was 41.2 (possible score: 10-50) indicating somewhat positive attitudes, and the score of eating behaviors was 34.8 (possible score: 15-45). Subjects showed problems in eating habits such as having unbalanced diets and snack foods. 82.6% of subjects had unbalanced meals, and these percentages were higher in girls (87.2%) than in boys (78.1%, p < 0.05). Vegetables and fish/shellfish were the most disliked foods. Specific eating behaviors, such as eating slowly, eating grains and having processed foods less frequently, were better in girls than in boys (p < 0.05). Results also showed that majority of subjects need to improve specific behaviors including having diverse foods, eating meals slowly, having meals at regular times, having adequate foods in each food groups, and eating sweets or salty foods less frequently. Only 52.7% of subjects perceived their body images as normal, and 56.4% had experience of weight control. Reasons for weight control were different by gender (p < 0.05). Based on these findings, nutrition education for school children should focus on modifying eating habits or eating behaviors, by suggesting practically applicable methods and providing nutrition information that is interesting and suitable to school-aged children.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.919-927
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• 2019

In this paper, we propose an accurate camera calibration method for acquiring multiview stereoscopic images. Generally, camera calibration is performed by using checkerboard structured patterns. The checkerboard pattern simplifies feature point extraction process and utilizes previously recognized lattice structure, which results in the accurate estimation of relations between the point on 2-dimensional image and the point on 3-dimensional space. Since estimation accuracy of camera parameters is dependent on feature matching, accurate detection of checkerboard corner is crucial. Therefore, in this paper, we propose the method that performs accurate camera calibration method through accurate detection of checkerboard corners. Proposed method detects checkerboard corner candidates by utilizing 1-dimensional gaussian filters with succeeding corner refinement process to remove outliers from corner candidates and accurately detect checkerboard corners in sub-pixel unit. In order to verify the proposed method, we check reprojection errors and camera location estimation results to confirm camera intrinsic parameters and extrinsic parameters estimation accuracy.

• Journal of Broadcast Engineering
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• v.24 no.5
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• pp.849-858
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• 2019

Recent developments in computer graphics technology and image processing technology have increased interest in point cloud technology for inputting real space and object information as three-dimensional data. In particular, point cloud technology can accurately provide spatial information, and has attracted a great deal of interest in the field of autonomous vehicles and AR (Augmented Reality)/VR (Virtual Reality). However, in order to provide users with 3D point cloud contents that require more data than conventional 2D images, various technology developments are required. In order to solve these problems, an international standardization organization, MPEG(Moving Picture Experts Group), is in the process of discussing efficient compression and transmission schemes. In this paper, we provide a region division transfer method of 3D point cloud content through extension of existing MPEG-DASH (Dynamic Adaptive Streaming over HTTP)-SRD (Spatial Relationship Description) technology, quality parameters are further defined in the signaling message so that the quality parameters can be selectively determined according to the user's request. We also design a verification platform for ROUTE (Real Time Object Delivery Over Unidirectional Transport)/DASH based heterogeneous network environment and use the results to validate the proposed technology.