• Korean Journal of Social Welfare
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• v.69 no.4
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• pp.177-202
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• 2017

We usually expect that children in residential care are not able to have excellent academic achievement, even though their school achievement in adolescence is crucial as a part of whole lifespan development. The purpose of this study is to carefully understand characteristics and experiences of only a few academically talented children in residential care and to find out the practical suggestion to support the academic performance of children in residential care. For this purpose, we had interviewed eight children in depth and analyzed the data using a qualitative case study method. As a result, we found a total of 21 subcategories and 5 categories. The categories included that 'always being faithful despite being not fast', 'believing myself when I face limitations', 'conflict in high support and high expectation', 'sometimes refusing to support on me, but I am leaning on my mind', 'relieving anxiety by studying'. In conclusion, we found that the central theme of 'running to change prejudice into hope' were found through the cases with excellent academic achievement. Based on the results, we suggested the guidelines to consider when developing and providing the academic support services for children in residential care.

• Korean Journal of Social Welfare Studies
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• v.41 no.1
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• pp.119-144
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• 2010

This study advances the knowledge of developmental patterns in affiliation with delinquent peers and delinquency during adolescence; data were obtained from waves 1-5 (2003-2007) of the Korea Youth Panel Survey. Semi-parametric group-based modeling (SGM) identified 3 affiliative trajectories of delinquent peers from age 13 to 16: rarely or never, persistently affiliative, and declining groups; and five developmental trajectories of delinquency: non-offending, late onset, low-level continuous, desisting, and chronic groups. A joint trajectory analysis predicted the membership of delinquency trajectories conditional on delinquent peer trajectories. Persistently affiliative group was more likely than others to follow chronic trajectory of delinquency; the rarely or never affiliative group was more likely to be non-offending. This study may help reconcile different theoretical models such as influence, selection, and enhancement models with respect to the role of delinquent peers in delinquency. The distinct theoretical models are equally valid, albeit each model pertains to a specific aspect of longitudinal patterns of affiliation with delinquent peers. Implications of this study for youth welfare were discussed to reduce increased risks for both affiliation with delinquent peers and delinquency.

• Korean Journal of Social Welfare Studies
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• v.42 no.3
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• pp.183-206
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• 2011

This study examined the longitudinal relationship between academic achievement and school satisfaction using a data of the Seoul Panel Study of Children(SPSC). Fully autoregressive cross-lagged analysis and multi-group comparison were performed to measure the longitudinal relationship between two constructs as well as differences between poverty and non-poverty groups. The results showed that both academic achievement and school satisfaction were stable over time in non-poverty group. Academic achievement at the 4th grade significantly affected the school satisfaction at the 6th grade and it subsequently affected on the academic achievement at the 8th grade in non-poverty group. In contrast, academic achievement was not consistent over time in poverty group. Only the school satisfaction at the 6th grade affected the academic achievement at the 8th grade. The findings of this study have various practical implication for school interventions. It is more important to keep supporting the children to maintain the level of academic achievement in non-poverty group. While, in poverty group, it is essential to make school satisfaction and academic motivation increase with school attachment programs.

• Korean Journal of Social Welfare Studies
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• v.41 no.3
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• pp.29-56
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• 2010

One of the most popular keywords in 21th century is "Information Society". Information Society improves the overall quality of human life, but increases the negative aspects such as internet addiction and digital divide. The purpose of this study is to understand the vicious cycle between socio-economic disparities and digital divide. This study analyzed the effects of poverty on school maladjustment and academic achievement and mediation effects by using parental monitoring and internet use types as mediators. Data were obtained from the Korea Youth Panel Survey(KYPS). Structural equation modeling was employed for statistical analyses. The result showed that poverty reduced parental monitoring and information-oriented type of internet use. Youth who used less information-oriented type showed more school maladjustment and less academic achievement. However, the relationship between poverty and entertainment-oriented type was non-significant. Thus, parental monitoring and the internet use types were one of the main pathways which can affect school maladjustment and academic achievement among youth in poverty. There was the possible vicious cycle between poverty and digital divide. Based on this study, we strongly suggest improvement of the media competence to solve the problem of digital divide among youth in poverty.

• Journal of Internet Computing and Services
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• v.24 no.5
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• pp.85-96
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• 2023

With advance of cloud computing technology, Blockchain as a Service of Cloud Service Provider has been utilized in various areas such as e-Commerce and financial companies to manage customer history and distribution history. However, if users' search history, purchase history, etc. are to be utilized in a BaaS in areas such as recommendation algorithms and search engine development, the users' search queries will be exposed to the company operating the BaaS, and privacy issues will be occured. Z. Guan et al. ensure the unlinkability between users' search query and search result using searchable encryption, and based on the inner product similarity, they select Top-k results that are highly relevant to the users' search query. However, there is a problem that the Top-k results selection may be not possible due to ties of inner product similarity, and BaaS over cloud is not considered. Therefore, this paper solve the problem of Z. Guan et al. using cosine similarity, so we improve accuracy of search result. And based on this, we design a BaaS with secure Top-k search that improved accuracy. Furthermore, we design a smart contracts that preserve privacy of users' search and obtain Top-k search results that are highly relevant to the users' search.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.118-126
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• 2009

Benthic diatoms are very important primary producers in understanding estuary ecosystems and their productions are largely varied by their photo-physiological characteristics. The short-term effects of increased temperature on the photosynthetic and photo-physiological characteristics of cultured different species of benthic diatoms (Navicula sp., Nitzschia sp., Cylindrotheca closterium, and Pleurosigma elongatum) were investigated by measuring their PSII-fluorescence kinetics using a Diving-PAM. Photosynthesis versus irradiance curves were measured every two hours at six different temperatures (10, 15, 20, 25, 30, and $35^{\circ}C$) for twenty-four hour. The effective quantum yield of PSII ($\Phi_{PSII}$) for most of the species showed a decreasing trend with increased temperature. The relative maximum electron transport rate (rETRmax) was significantly increased up to the optimum temperature level and then sharply decreased. Relative to the values of other parameters, the maximum light use coefficient ($\alpha$) was not substantially changed at lower temperature levels (<$30^{\circ}C$) but significantly decreased only at higher temperatures (30 and $35^{\circ}C$). The light saturation coefficient ($E_K$) mirrored the rETRmax temperature response. In regards to the temperature acclimation abilities of the four species with time, Navicula sp. and C. closterium acclimated to short-term changes in temperature through their photo-physiological adjustments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.25-35
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• 2010

The biodiversity of eukaryotic plankton has commonly been used to evaluate the status of aquatic ecosystems. Therefore, an accurate and rapid method for species identification is needed to reveal the biodiversity of environmental water samples. To date, molecular methods have provided a great deal of information that has enabled identification of the hidden biodiversity in environmental samples. In this study, we utilized environmental polymerase chain reaction (PCR) and constructed the 18S nuclear ribosomal RNA clone library from environmental water samples in order to develop more efficient methods for species identification. For the molecular analysis, water samples were collected from the Seonakdong River (Gimhae Bridge) and the coast of Namhae，(Namhaedo). Colony PCR and restriction fragment length polymorphism of PCR (PCR-RFLP) were then adopted to isolate unique clones from the 18S rDNA clone library. Restriction fragment length polymorphism pattern analysis of the Gimhae Bridge sample revealed 44 unique clones from a total of 60 randomly selected clones, while analysis of the Namhae sample revealed 27 unique clones from 150 clones selected at random. A BLAST search and subsequent phylogenetic analysis conducted using the sequences of these clones revealed hidden biodiversity containing a wide range of taxonomic groups (Heterokontophyta (7), Ciliophora (23), Dinophyta (1), Chytridiomycota (1), Rotifera (1) and Arthropoda (11) in the Gimhae Bridge samples Ciliophora (4), Dinophyta (3), Cryptophyta (1), Arthropoda (19) in the Namhae samples). Therefore, the molecular monitoring method developed here can provide additional information regarding the biodiversity and community structure of eukaryotic plankton in environmental samples and helps construct a useful database of biodiversity for aquatic ecosystems.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.1
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• pp.129-141
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• 2024

Amidst the acceleration of digital transformation across various sectors, the financial market is increasingly focusing on the development of digital and electronic payment methods, including currency. Among these, Central Bank Digital Currencies (CBDC) are emerging as future digital currencies that could replace physical cash. They are stable, not subject to value fluctuation, and can be exchanged one-to-one with existing physical currencies. Recently, both domestic and international efforts are underway in researching and developing CBDCs. However, current CBDC systems face scalability issues such as delays in processing large transactions, response times, and network congestion. To build a universal CBDC system, it is crucial to resolve these scalability issues, including the low throughput and network overload problems inherent in existing blockchain technologies. Therefore, this study proposes a solution based on reinforcement learning for handling large-scale data in a CBDC environment, aiming to improve throughput and reduce network congestion. The proposed technology can increase throughput by more than 64 times and reduce network congestion by over 20% compared to existing systems.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.826-833
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• 2014

Driven by both environmental and economic reasons, the development of small to medium scale GTL(gas-to-liquid) process for offshore applications and for utilizing other stranded or associated gas has recently been studied increasingly. Microchannel GTL reactors have been prefrered over the conventional GTL reactors for such applications, due to its compactness, and additional advantages of small heat and mass transfer distance desired for high heat transfer performance and reactor conversion. In this work, multi-microchannel reactor was simulated by using commercial CFD code, ANSYS FLUENT, to study the geometric effect of the microchannels on the heat transfer phenomena. A heat generation curve was first calculated by modeling a Fischer-Tropsch reaction in a single-microchannel reactor model using Matlab-ASPEN integration platform. The calculated heat generation curve was implemented to the CFD model. Four design variables based on the microchannel geometry namely coolant channel width, coolant channel height, coolant channel to process channel distance, and coolant channel to coolant channel distance, were selected for calculating three dependent variables namely, heat flux, maximum temperature of coolant channel, and maximum temperature of process channel. The simulation results were visualized to understand the effects of the design variables on the dependent variables. Heat flux and maximum temperature of cooling channel and process channel were found to be increasing when coolant channel width and height were decreased. Coolant channel to process channel distance was found to have no effect on the heat transfer phenomena. Finally, total heat flux was found to be increasing and maximum coolant channel temperature to be decreasing when coolant channel to coolant channel distance was decreased. Using the qualitative trend revealed from the present study, an appropriate process channel and coolant channel geometry along with the distance between the adjacent channels can be recommended for a microchannel reactor that meet a desired reactor performance on heat transfer phenomena and hence reactor conversion of a Fischer-Tropsch microchannel reactor.

• Korean Journal of Animal Reproduction
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• v.23 no.2
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• pp.175-180
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• 1999

Blood chemical values and sex steroid hormone concentration of repeat breeder and reproductive disorder in Hanwoo, which were bred in Chunchon areas, were examine to establish the basic physiological maker. The concentrations of albumin, blood urea nitrogen(BUN), calcium(Ca), cholesterol, creatinine, glucose, phosphorous, total protein and triglycerides in repeat breeder and reproductive disorder were 3.28$\pm$0.05 and 3.27$\pm$0.04 g/㎗, 11.07$\pm$0.61 and 12.69$\pm$0.88 mg/㎗, 9.98$\pm$0.10 and 9.56$\pm$0.11mg/㎗, 105.75$\pm$3.57 and 126.78$\pm$5.66mg/㎗, 1.62$\pm$0.05 and 1.65$\pm$0.09 mg/㎗, 67.46$\pm$9.07 and 76.97$\pm$3.76mg/㎗, 6.13$\pm$0.36 and 6.11$\pm$0.26mg/㎗, 5.82$\pm$0.08 and 6.18$\pm$0.08 g/㎗ , 12.82$\pm$1.46 and 15.19$\pm$1.61mg/㎗, respectively. Among the blood chemical values, Ca, cholesterol and inorganic phosphorous levels in repeat breeder and reproductive disorder were slightly higher than those in normal cows. The progesterone levels of pregnancy(0.18~6.56 ng/$m\ell$) and non-pregnancy(0.15~5.46ng/$m\ell$) cows at estrus cycle were showed similar trends from 0 day to 18 days. Those of pregnancy cows were increased gradually from 18 days to 180 days(5.90~7.51 ng/$m\ell$), while those of non-pregnancy cows were dramatically drop at 21 days (0.18$\pm$0.03mg/㎗). The concentrations of estrogen and progesterone in repeat breeder and reproductive disorder were 57.42$\pm$5.03, 56.76$\pm$8.73 pg/$m\ell$ and 6.26$\pm$0.83, 9.41$\pm$1.85 ng/$m\ell$ . respectively. These results indicate that blood chemical values in repeat breeder and reproductive disorder were not greatly difference in normal cows except for Ca, cholesterol, BUN and inorganic phosphorous. Since the progesterone levels in repeat breeder and reproductive disorder was maintained to the luteal phase levels of normal cows, it may cause of failing of conception and next estrus cycle.