• Journal of Broadcast Engineering
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• v.22 no.3
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• pp.350-365
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• 2017

Steganography is a technique for secret data communication, which is not perceived by third person between a receiver and a transmitter. It has been developed for thousands of years for the transmission of military, diplomatic or business information. The development of digital media and communication has led to the development of steganography techniques in modern times. Technic of image steganography include the LSB, which fixes the number of embedded bits into a pixel, and PVD, which exploits the difference value in the neighboring pixel pairs. In the case of PVD image steganography, a large amount of information is embedded fluidly by difference value in neighboring pixel pairs and the designed range table. However, since the secret information in order is embedded, if an error of the number of embedded bits occurs in a certain pixel pair, all subsequent information will be destroyed. In this paper, we proposes the method, which improve the vulnerability of PVD property about external attack or various noise and extract secret information. Experimental process is comparison analysis about stego-image, which embedded various noise. PVD shows that it is not possible to preserve secret information at all about noise, but it was possible to robustly extract secret information for partial noise of stego-image in case of the proposed PVD image steganography with locally-fixed number of embedding bits.

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.326-331
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• 1989

Superconducting fiber of high Tc $YBa_2Cu_3O_{7-{\sigma}}$ was successfully prepared by the sol-gel method. The stoichiometric mixture of Y, Ba and Cu nitrates was dissolved in water, to which citric acid solution was added. Then ammonium hydroxide was added to the mixture in order to increase the pH to a value between 5.8 and 6.2. The mixture was heated carefully to form a homogeneous colloid sol at 358 K. The solution was viscous enough to draw a long gel fiber, which was then heated at 1223K for 8 hrs. under oxygen partial pressure of $Po_2$ = 1 atm., cooled slowly and annealed at 723K for 13 hrs.. The reacted superconducting sample maintained a fiber form with some shrinkage of its volume. The superconducting transition temperatures (Tc, onset and Tc, offset) of $YBa_2Cu_3O_{7-{\sigma}}$ have been determined to be approximately 95K and 82K, respectively. The superconducting phase was also confirmed by Meissner effect at liquid nitrogen boiling temperature.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.171-178
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• 2018

The ocean is a harsh environment and Korea Coast Guard officers often face the threat of death or going missing in the line of duty. In order to promptly identify unknown bodies during mishaps, Korea Coast Guard Research Center has established an identification system using the DNA of its officers. This collected DNA can also be entombed in National Cemeteries when the remains are not recovered. The storage, disposal and quality control of the materials are overseen by the Governing Committee according to the Enforcement Rules for the Human Biological Materials Storage Project for the Identification of Officers Killed or Gone Missing in Action. Approximately 700 bodies are found per year along the Korean coast. An alternative method should be put in place for when identification through fingerprints and teeth are not applicable due to severe decomposition or partial recovery. We believe it would greatly contribute to helping identify the unknown bodies if the storage project could expand its data to include marine industry workers, relevant researchers and those involved in marine leisure activities.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.397-404
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• 2000

This study was carried out to investigate the influence of the road structure and site conditions on side-ditch stability of forest road. For experimental purposes, the forest road in the Kwangrung Experimental Forest, Korea Forestry Research Institute, was chosen as a study site. A total of 556 plots wes set up as every longitudinal gradient changing points by belt-transect method. Data of 10 road structural characteristics and side-ditch stability were collected from each plot and analysed by Quantification II. The main factors in order of partial correlation coefficient were longitudinal gradient, road position, inclination of cut-slope, constituent material of cut-slopes, distance of surface flow, cross-sectional shape of road, pavement material, vegetation of cut-slopes and length of cut-slope. The erosion of side-ditch of forest road occurred in the following cases; more than 8% of the longitudinal gradient, road position of hill under side and foot hill, more than $50^{\circ}$ of inclination of cut-slope, constituent material of cut-slopes of hard soil and gravel soil, more than 80m of distance of surface flow, pavement material with earth or gravel, more than medium covered of vegetation of cut-slopes, and the straight and convex form of road-bed.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.2
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• pp.71-78
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• 2012

The digital tachograph is a device that automatically records speed and distance of a vehicle, together with the driver's activity and vehicle status at an accident. It records vehicle speed, break status, acceleration, engine RPM, longitude and latitude of GPS, accumulated distance, and so on. European Commission regulation made digital tachographs mandatory for all trucks from 2005. Republic of Korea made digital tachographs mandatory for all new business vehicles from 2011 and is widening the range of vehicles that must install digital tachographs year by year. This device is used to analyze driver's daily driving information and car accidents. Under a car accident that makes the device reliability unpredictable, it is very important to store driving information with maximum reliability for its original mission. We designed and implemented a practical digital tachograph. This paper presents a storage scheme that consists of a first storage device with small capacity at a high reliability and a second storage device with large capacity at a low cost in order to reliably records data with a hardware at a low cost. The first storage device records data in a SLC NAND flash memory in a log-structured style. We present a reverse partial scan that overcomes the slow scan time of log-structured storages at the boot stage. The scheme reduced the scan time of the first storage device by 1/50. In addition, our design includes a scheme that fast stores data at a moment of accident by 1/20 of data transfer time of a normal method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.227-236
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• 2016

This study tested the effects of stress on smartphone addiction via depression and self-efficacy among college students, and the analysis results were as follows: setting mediator and extra variables significantly correlated with the criterion variable as covariates and applying the regression analysis and SPSS Macro as well as bootstrapping method, to verify the mediating effects of depression and self-efficacy in stress and smartphone addiction. This study analyzed the direct effects of stress on the depression, self-efficacy, and smartphone addiction of college students and found that stress had direct effects on their depression and self-efficacy and also indirect effects on their smartphone addiction via depression and self-efficacy. Both depression and self-efficacy had dual and partial mediating effects on the influences of stress on their smartphone addiction. Stress had significant dual mediating effects on their smartphone addiction via the indirect paths of depression and self-efficacy, and high stress also had significant direct effects on their smartphone addiction, thus validating the dual mediation model. These findings demonstrate the need to develop programs to mitigate the stress and depression of college students and enhance their self-efficacy in order to reduce their smartphone addiction.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.5-15
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• 2014

Target reliability index in the limit state design indicated the safety margin and it is important to determine the partial factor. To determine the target reliability index which is needed in the limit state design, the six design and construction case histories of gravel compaction piles (GCP) were investigated. The limit state functions were defined by bulging failure for the major failure mode of GCP. The reliability analysis were performed using the first order reliability method (FORM) and the reliability index was calculated for each ultimate bearing capacity formulation. The reliability index of GCP tended to be penportional to the safety factor of allowable stress design and average value was ${\beta}$=2.30. Reliability level that was assessed by reliability analysis and target reliability index for existing structure foundations were compared and analyzed. As a result, The GCP was required a relatively low level of safety compared with deep and shallow foundations and the currd t reliability level were similar to the target reliability in the reinforced earth retaining-wall and soil-nailing. Therefore the target reliability index of GCP suggested as ${\beta}_T$=2.33 by various literatures together with the computed reliability level in this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.594-600
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• 2021

Curved beam structures are generally used as components in structures such as railroad bridges and vehicles. The stability analysis of curved beams has been studied by a large number of researchers. Due to the complexities of structural components, it is difficult to obtain an analytical solution for any boundary conditions. In order to overcome these difficulties, the differential quadrature method (DQM) has been applied for a large number of cases. In this study, DQM was used to solve the complicated partial differential equations for buckling analysis of curved beams. The governing differential equation was deduced and solved for beams subjected to uniformly distributed radial loads. Critical loads were calculated with various opening angles, boundary conditions, and parameters. The results of the DQM were compared with exact solutions for available cases, and the DQM gave outstanding accuracy even when only a small number of grid points was used. Critical loads were also calculated for the in-plane inextensional buckling of the asymmetric curved beams, and two theories were compared. The study of a beam with extensibility of the arch axis shows that the effects on the critical loads are significant.

• 한국노년학
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• v.37 no.2
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• pp.293-308
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• 2017

This study aims to examine Life Managers for Elderly People Living Alone (LMEPLAs) in Seoul regarding their traumatic experience and the status of their posttraumatic stress disorder and also how they are coping with it in order to find out ways to improve it. As a study method, we investigated LMEPLAs in Seoul through a self-administered survey regarding whether they had faced any traumatic experience, types of their traumatic experience, diagnosis on posttraumatic stress, and the status of their coping with traumatic experience. According to the study results, 186 respondents (37.57%) have been found to indicate either partial or complete posttraumatic stress symptoms, but the status of their coping with it is very poor. The followings are the results of our discussion. First, it is needed to find out life managers suffering from posttraumatic stress disorder and build up a system to manage them consistently. Second, it is necessary to vitalize education about traumatic experience and posttraumatic stress management. Third, it is urgently needed to build up a system to support life managers who have faced any traumatic experience or been diagnosed to have posttraumatic stress disorder. Fourth, it is demanded to cultivate and arrange experts equipped with specialized knowledge and technique. Fifth, it is needed for them to build a network with medical institutes to receive a prompt diagnosis and specialized treatment.

• Journal of Korean Classical Literature and Education
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• no.16
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• pp.147-179
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• 2008

Classical literature texts have been transmitted and recreated as subjective meanings in a wide variety of genres. Authors recreate another world with their own imagination and classical literature texts. This study has been conducted to analysis 'OnDal's Dream' which is an adaptation from 'OnDalJeon' in order to figure out the method of inheritance and the subject and message of the adaptation. The process of inheritance and acculturation appears in the literary world. Some adaptations stick to the genre of the original text, other adaptations change to various genres. There is the process of inheritance and acculturation in the aspect of structure of the adaptation 'OnDal's Dream'. lntertextuality can be found between 'OnDalJeon' and 'OnDal's Dream' in terms of the stages such as 'confrontation' between the ego and the world and 'overcoming' hardships. However, the recreation text has acculturation of the structure that shows the potential desire for elevation of social status at the end part of the work so I could possibly show that the adaptation has limitation because it was far from the dream of common people and laborers at that time. There are different structures and recognition systems between 'OnDal Jeon' and 'OnDal's Dream' because the formal is an epic tale the other is lyric tale. An epic tale has some partial symbols in its story line, while an lyric tale is a symbol as a whole. There is an exhibition of deep emotion which is subjectivized and symbolized against the world in the adaptation 'OnDal's Dream'. And the inheritance of unreality, which is acculturation to the world of dream, from the original text can be found in the adaptation. First of all, study between the original text and the recreation text should be conducted in terms of intertextuality. Secondly, an instruction on the inheritance which is based on intertextuality between the original text and the recreation text should be conducted. Thirdly, an instruction about the structure of a genre and differences of recognition systems according to inheritance or conversion of a genre. It will be helpful for children to stimulate to take an interest in classical literature texts and traditional arts, to learn more recreation texts, and to develop the practical ability to recreate works. Based on above study, an instruction which shows a spiritual value of literature should be conducted.